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  • Birk, Udo (2017): Super-Resolution Microscopy. A Practical Guide. Weinheim, Germany: Wiley-VCH

    Abstract: This unique book on super-resolution microscopy techniques presents comparative, in-depth analyses of the strengths and weaknesses of the individual approaches. It was written for non-experts who need to understand the principles of super-resolution or who wish to use recently commercialized instruments as well as for professionals who plan to realize novel microscopic devices. Explaining the practical requirements in terms of hardware, software and sample preparation, the book offers a wealth of hands-on tips and practical tricks to get a setup running, provides invaluable help and support for successful data acquisition and specific advice in the context of data analysis and visualization. Furthermore, it addresses a wide array of transdisciplinary fields of applications. The author begins by outlining the joint efforts that have led to achieving super-resolution microscopy combining advances in single-molecule photo-physics, fluorophore design and fluorescent labeling, instrument design and software development. The following chapters depict and compare current main standard techniques such as structured illumination microscopy, single-molecule localization, stimulated emission depletion microscopy and multi-scale imaging including light-sheet and expansion microscopy. For each individual approach the experimental setups are introduced, the imaging protocols are provided and the various applications illustrated. The book concludes with a discussion of future challenges addressing issues of routine applications and further commercialization of the available methods. Guiding users in how to make choices for the design of their own experiments from scratch to promising application, this one-stop resource is intended for researchers in the applied sciences, from chemistry to biology and medicine to physics and engineering.

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  • Studer, Bruno (2010): Netzwerkmanagement und Netzwerksicherheit. Ein Kompaktkurs für Praxis und Lehre. Zürich: vdf Hochschulverlag AG an der ETH Zürich (Vdf Praxis und Lehre. Informatik)

    Abstract: Im Zeitalter der Globalisierung wird Kommunikations- und Informationsmanagement immer wichtiger – und doch bestehen gerade hier enorme Gefahrenquellen für Unternehmen und Privatpersonen. Mit zunehmender Vernetzung steigt die Gefahr, dass in die komplexen Kommunikationssysteme eingedrungen und grosser Schaden angerichtet wird. Neben speziellen Sicherheitssystemen wie Firewalls oder Verschlüsselungsprogrammen sorgt vor allem ein gutes Netzwerkmanagement dafür, dass weniger Sicherheitslecks entstehen bzw. diese rascher behoben werden können. Hinzu kommt, dass der umfassende und räumlich oft weit verstreute Arbeitsaufwand dadurch optimiert wird. "Netzwerkmanagement und Netzwerksicherheit" bietet nicht nur einen praxisnahen Überblick zu den Vorzügen der speziellen Managementmodelle (SNMP, TMN, Java-Management) sowie zu wichtigen Aspekten des Service-Managements (ITIL); es werden vor allem die möglichen Bedrohungen für die IT-Sicherheit aufgezeigt – und wie man ihnen entgegenwirkt. Dieser Kompaktkurs richtet sich an Studierende und Praktiker gleichermassen. Übersichtlich und leicht verständlich zeigt der Autor auf, worauf man bei der IT-Sicherheit in Firmen, aber auch im privaten Bereich achten muss – und wie man sie oft schon mit kleinen Mitteln optimieren kann.

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  • Hofstetter, Rolf; Wenk, Bruno (2011) : Freies WLAN in den Alpen In: Semar, Wolfgang: Informationsgesellschaft und Infrastrukturpolitik im Alpenraum: Arge Alp Tagung, 23.-24. September 2010, Chur. Hochschule für Technik und Wirtschaft HTW Chur. Schweizerisches Institut für Informationswissenschaft: Chur (Churer Schriften zur Informationswissenschaft. Arbeitsbereich Informationswissenschaft), S. 34-38. Online verfügbar unter https://www.fhgr.ch/fhgr/angewandte-zukunftstechnologien/schweizerisches-institut-fuer-informationswissenschaft-sii/publikationen/churer-schriften/, zuletzt geprüft am 18.12.2020

     

    Abstract: Zwischen den Agglomerationen und Randgebieten besteht bezüglich der mobilen Zugänge offensichtlich ein digitaler Graben, der mit freien WLAN-Zugängen beseitigt werden kann. Freie WLAN-Zugänge sind nichts Neues. Es gibt heute schon Restaurations- und Hotelbetriebe sowie Tourismusorte, welche sich mit dem freien WLAN-Zugang einen Wettbewerbsvorteil sichern.

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  • Brunner, Lars; Salvator, Mario; Roebrock, Philipp; Birk, Udo (2021) : Chess recognition using 3D patterned illumination camera In: Osten, Wolfgang; Nikolaev, Dmitry P.; Zhou, Jianhong (Hg.): Thirteenth International Conference on Machine Vision (ICMV 2020): Proceedings: International Conference on Machine Vision (ICMV): Rom, 2. - 6. November. SPIE The international society for optics and photonics (Proceedings of SPIE), S. 520-527

    DOI: https://doi.org/10.1117/12.2587054 

    Abstract: Computer Vision has been applied to augment traditional board games such as Chess for a number of reasons. While augmented reality enhances the gaming experience, the required additional hardware (e.g. head gear) is still not widely accepted in everyday leisure activities, and therefore, camera based methods have been developed to interface the computer with the real-life chess board. However, traditional 2D camera approaches suffer from ill-defined environmental conditions (lighting, viewing angle) and are therefore severely limited in their application. To answer this issue, we have incorporated a consumer-grade depth camera based on patterned illumination. We could show that in combination with traditional 2D color images, the recognition of chess pieces is made easier, which allows seamless integration of the real-life chess pieces with the computer program. Our method uses a fusion approach from depth and RGB camera data and is suitable for two distant players to play against each other, using two physical sets of chess.

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  • Komm, Dennis; Hauser-Ehninger, Ulrich; Matter, Bernhard; Staub, Jacqueline; Trachsler, Nicole (2021) : Computational Thinking in Small Packages In: Kori, Külli; Laanpere, Mart (Hg.): Informatics in Schools: Engaging Learners in Computational Thinking: Proceedings: 13th International Conference on Informatics in Schools: Situation, Evolution and Perspectives (ISSEP): Tallinn, 16. - 18. November 2020: Cham: Springer (Lecture Notes in Computer Science), S. 170-181

    DOI: https://doi.org/10.1007/978-3-030-63212-0_14 

    Abstract: This article describes an approach to foster computational thinking in different school subjects. Our approach includes several teaching units (packages) that are self-contained and have been designed for university courses attended by prospective and graduate primary and secondary school teachers. Around 30 packages have been designed so far and together cover eight aspects of computational thinking in six different subjects. In this report, some examples are sketched out together with the experiences gathered.

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  • Merbold, Hannes; Iten, Marc-Alexander; Catregn, Gion-Pol (2020) : Multispectral Time-of-Flight Range Imaging. Towards a 3.5 D Camera: Imaging and Applied Optics: Proceedings: Imaging and Applied Optics Congress: Online, 22. - 26. Juni: Washington: Optica

    Abstract: Time-of-flight cameras with sequenced multi-wavelength illumination or swing-in bandpass filters allow recording three spatial dimensions as well as a limited number of spectral data points.

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  • Birk, Udo; Roebrock, Philipp (2018) : User-position aware adaptive display of 3D data without additional stereoscopic hardware In: Verikas, Antanas; Nikolaev, Dmitry P.; Radeva, Petia; Zhou, Jianhong (Hg.): Eleventh International Conference on Machine Vision (ICMV 2018): Proceedings: International Conference on Machine Vision (ICMV): München, 1. - 3. November. SPIE The international society for optics and photonics (Proceedings of SPIE). Online verfügbar unter https://doi.org/10.1117/12.2522678, zuletzt geprüft am 14.02.2020

     

    Abstract: Stereoscopic vision modules have seen limited success in both engineering and consumer world, due to the required additional hardware (image acquisition, Virtual Reality headsets, 3D glasses). In the last years, especially the gaming and education sectors have benefited from such specialized headgear, providing virtual or augmented reality. However, many other industrial and biomedical applications such as e.g. computer aided design (CAD) or tomographic data display, so far have not fully exploited the increased 3D rendering capabilities of present-day computer hardware. We present an approach to use standard desktop PC hardware (monitor and webcam) to display user-position aware projections of 3D data without additional headgear. The user position is detected from webcam images, and the rendered 3D data (i.e. the view) is adjusted to match the corresponding user position, resulting in a quasi virtual reality rendering, albeit without the 3D effect of proper 3D head-gear. The approach has many applications from medical imaging, to construction and CAD, to architecture, to exhibitions, arts and performances. Depending on the user location, i.e. the detected head position, the data is rendered differently to attribute for the user view angle (zoom) and direction. As the user moves his or her head in front of the monitor, different features of the rendered object become visible. As the user moves closer to the screen, the view angle of the rendered data is decreased, resulting in a zoomed-in version of the rendered object.

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  • Merbold, Hannes; Catregn, Gion-Pol; Leutenegger, Tobias (2018) : Time-of-flight range imaging for underwater applications In: Soskind, Yakov G.: Photonic Instrumentation Engineering V: Proceedings: SPIE Photonics West: San Francisco. SPIE The international society for optics and photonics (Proceedings of SPIE). Online verfügbar unter https://doi.org/10.1117/12.2283476, zuletzt geprüft am 21.02.2020

     

    Abstract: Precise and low-cost range imaging in underwater settings with object distances on the meter level is demonstrated. This is addressed through silicon-based time-of-flight (TOF) cameras operated with light emitting diodes (LEDs) at visible, rather than near-IR wavelengths. We find that the attainable performance depends on a variety of parameters, such as the wavelength dependent absorption of water, the emitted optical power and response times of the LEDs, or the spectral sensitivity of the TOF chip. An in-depth analysis of the interplay between the different parameters is given and the performance of underwater TOF imaging using different visible illumination wavelengths is analyzed.

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  • Merbold, Hannes (2017) : Spatiotemporal imaging of THz wave propagation: Polaritonics versus near-field imaging In: IEEE: Proceedings of the 16th Workshop on Information Optics: Workshop on Information Optics (WIO): Interlaken. EPFL, Nanophotonics and Metrology Laboratory NAM, S. 1-3. Online verfügbar unter https://doi.org/10.1109/WIO.2017.8038178, zuletzt geprüft am 21.02.2020

    DOI: https://doi.org/10.1109/WIO.2017.8038178 

    Abstract: Two recently developed methods that allow visualizing the interaction of THz radiation with arbitrary structures, namely polaritonics and near-field imaging, are reviewed and compared. THz polaritonics, which relies on complex amplified laser systems, allows single-shot image acquisition in a plane perpendicular to the structures. THz near-field imaging, on the other hand, requires only femtosecond oscillators but is a slower raster scanning technique providing images parallel to the structure plane.

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  • Geilinger, Eva; Janett, Patrik; Gasser, Stefan; Sivitos, Stamatis; Zuloaga, Francisco; Bush, Eric (2015) : Luminaire efficiency. What mandatory and voluntary labels achieve, and what they should achieve in the future In: Luca, Andrea de; Bertoldi, Paolo (Hg.): Proceedings of the 8th international conference on energy efficiency in domestic appliances and lighting: Re-edition: EEDAL: Luzern, 26. August, S. 1146-1158. Online verfügbar unter 10.2790/012477, zuletzt geprüft am 28.02.2020

     

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  • Leutenegger, Tobias; Studer, Bruno (2015) : First Swiss bachelor in Photonics In: Cormier, Eric; Sarger, Laurent (Hg.): Education and Training in Optics and Photonics: Proceedings: ETOP: Bordeaux, 25. Juni - 2. Juli. SPIE The international society for optics and photonics (Proceedings of SPIE). Online verfügbar unter https://doi.org/10.1117/12.2223216, zuletzt geprüft am 28.02.2020

     

    Abstract: Swissmem, the Swiss association of mechanical and electrical engineering industries, founded a new photonics group in 2013. This reflects the importance of this key technology for Switzerland. Swissmem requested from the Swiss Universities of Applied Sciences to introduce a new bachelor program to fulfill the increasing demand of the Swiss industry of young academics in the field of photonics. Optech Consulting is investigating the Swiss photonics market since many years on behalf of Swissphotonics, the Swiss national thematic network for photonics. The study concluded that the total production volume of the Swiss photonics industry in the year 2013 was 3 billion Swiss francs and a slight growth is expected for 2014. The University of Applied Science HTW Chur is located in the Eastern part of Switzerland. This area of the Rhine valley is a technology cluster of innovative companies in the field of optics and electronics. The industry is growing and the R&D departments of the worldwide active companies are lacking well-educated photonics engineers. The HTW Chur is dedicated to establish the first Swiss bachelor in Photonics. Supported by strong industrial players and an excellent network, the HTW Chur developed different job descriptions and a complete curriculum, which reflect the needs of the Swiss photonics industry. Almost 60% of the ECTS of this national degree program are assigned to photonics specific courses and the practical projects are organized in close collaboration with the photonics industry. Curriculum, job descriptions and the industrial needs will be discussed in detail in this paper.

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  • Weichselbraun, Albert; Süsstrunk, Norman (2015) : Optimizing Dependency Parsing Throughput In: Fred, Ana; Dietz, Jan; Aveiro, David; Liu, Kecheng; Filipe, Joaquim (Hg.): Proceedings of the 7th International Joint Conference on Knowledge Discovery, Knowledge Engineering and Knowledge Management, 1: Joint Conference on Knowledge Discovery, Knowledge Engineering and Knowledge Management: Lissabon, 12. - 14. November: 3, S. 511-516. Online verfügbar unter 10.5220/0005638905110516, zuletzt geprüft am 28.02.2020

     

    Abstract: Dependency parsing is considered a key technology for improving information extraction tasks. Research indicates that dependency parsers spend more than 95% of their total runtime on feature computations. Based on this insight, this paper investigates the potential of improving parsing throughput by designing feature representations which are optimized for combining single features to more complex feature templates and by optimizing parser constraints. Applying these techniques to MDParser increased its throughput four fold, yielding Syntactic Parser, a dependency parser that outperforms comparable approaches by factor 25 to 400.

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  • Merbold, Hannes; Bitzer, Andreas; Carbone, Fabrizio; Murk, Axel; Wallauer, Jan; Walther, Markus; Feurer, Thomas (2012) : Adjusting the functionality of terahertz split-ring resonators through geometry In: Betz, Markus; Elezzabi, Abdulhakem Y.; Song, Jin-Joo; Tsen, Kong-Thon (Hg.): Ultrafast Phenomena and Nanophotonics XVI: SPIE OPTO: San Francisco, California, USA, 21.-26. Januar: SPIE. Digital Library (SPIE Proceedings)

    DOI: https://doi.org/10.1117/12.908107 

    Abstract: We examine planar double split-ring resonators (SRRs) consisting of two concentric rings with either opposite, similar, or asymmetric gap orientation. Depending on the geometry we observe resonance hybridization, metamaterial induced transparency, or the excitation of dark resonances. These properties can be used for SRR based sensing applications, to realize strongly dispersive behavior, or for determining the optical properties of metals. We further find that THz SRRs featuring very narrow gaps on the micro- or nanoscale can provide in-gap enhancement factors of several 10,000, a property particularly useful for the realization of nonlinear THz experiments.

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  • Wenk, Bruno (2010) : Open educational resources (OER) inspire teaching and learning: Educon 2010: Annual Global Engineering Education Conference The Future of Global Learning in Engineering Education: IEEE Educon 2010 Conference: Madrid, 14.-16. April: [Madrid]: UPM, Servicio de Publicaciones, S. 435-441. Online verfügbar unter http://educon-conference.org/educon2010/, zuletzt geprüft am 18.12.2020

     

    Abstract: Open educational resources (OER) can significantly reduce the time required to prepare lectures. The prerequisites are that a desired resource can be found quickly and that its adequacy for the intended purpose can be estimated easily. Eventually, the resource should also be suitable for modification. In the first part we outline the requirements for the sourcing, storing, retrieval and exchange of open educational resources considering technical and legal aspects. In the second part we present a case study focusing on the user level perspective. We describe the searching for a particular OER (an online Moodle tutorial), the analysis of the resource found, its modification and the publishing of the modified resource on a repository.

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  • Bühringer, Maleachi; Berchtold, Jan; Büchel, Melanie; Dold, Claus; Bütikofer, Michael; Feuerstein, Mevina; Fischer, Wolfgang; Bermes, Christian; Siegwart, Roland (2010) : Inspection of high voltage power lines-a new approach In: Tosun, O.; Akin, H. L.; Tokhi, Mohammad Osman; Virk, Gurvinder S. (Hg.): Mobile robotics: Solutions and challenges: Proceedings of the Twelfth International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines: International Conference on Climbing and Walking Robots: Istanbul, 9. - 11. September: 2009. International Conference on Climbing and Walking Robots: Singapore; Hackensack: World Scientific, S. 455-462

    Abstract: This paper presents the "Cable Crawler", a mobile teleoperated robot to inspect high voltage power lines. Its mechanism allows riding on the topmost ground cable of high voltage power lines and crossing a set of mast tips as well as smaller obstacles autonomously and thus is not limited to just move from mast to mast. The robot consists of an aluminium chassis, six propulsion units and two spaces for cameras and other electronic components. Six electrical motors drive independently six rubber-coated rollers, two in a horizontal position to take the weight and four vertical ones. The four vertical rollers are pressed onto the wire by springs, which guarantees slipless propulsion in difficult situations. A Matlab program controls the drives independently. An optical camera is mounted on the prototype, which can rotate 360° and the image can be transmitted wireless to the user's computer monitor. With a mass of 58 kg and only six drives it consequently follows the industry's wish to have a robust, easy to maintain and rather cheap solution. Regarding the fields examined by the robot, the project concentrated on the detection of trees growing into proximity of the wires.

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  • Schafroth, Dario; Bermes, Christian; Bouabdallah, Samir; Siegwart, Roland (2010) : Modeling and System Identification of the muFly Micro Helicopter In: Valavanis, Kimon P.; Beard, Randal; Oh, Paul; Ollero, Aníbal; Piegl, Leslie A.; Shim, Hyunchui (Hg.): Selected papers from the 2nd International Symposium on UAVs, Reno, Nevada, U.S.A. June 8–10, 2009: Reno, 8. - 10. Juni: 2009: Dordrecht; Heidelberg; London; New York: Springer Science+Business Media, S. 27-47

    Abstract: An accurate mathematical model is indispensable for simulation and control of a micro helicopter. The nonlinear model in this work is based on the rigid body motion where all external forces and moments as well as the dynamics of the different hardware elements are discussed and derived in detail. The important model parameters are estimated, measured or identified in an identification process. While most parameters are identified from test bench measurements, the remaining ones are identified on subsystems using the linear prediction error method on real flight data. The good results allow to use the systems for the attitude and altitude controller design.

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  • Birk, Udo; Darrell, Alex; Konstantinidis, Nikos; Ripoll, Jorge (2010) : Correction of Lateral Movement and Spherical Aberrations in Optical Projection Tomography: Proceedings Biomedical Optics and 3-D Imaging: Biomedical Optics 2010: Miami, 11. - 14. April. Biomedical optics and 3-D imaging: Washington, DC: Optica Publishing Group

    Abstract: Non-invasive optical projection tomography (OPT) provides a method to image small animals in-vivo. We present two correction methods for this technique which can be applied after the images have been acquired. The first method allows to reconstruct specimens embedded in media with arbitrary refractive index, and the second method corrects for small movements of the specimens with respect to the detection system. We have tested the correction methods with computer simulated data and with samples of Parhyale hawaiensis embedded in sea water. These post-acquisition corrections prove to be a major step towards routine in-vivo imaging, and provide 3D analyses of OPT data which can not be rendered using standard reconstruction methods.

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  • Bermes, Christian; Bouabdallah, Samir; Schafroth, Dario; Siegwart, Roland (2009) : Design Parameters for Coaxial Rotary Wing MAVs with Passive Roll and Pitch Stability: 65th American Helicopter Society International Annual Forum: Volume 1 of 3: Grapevine, 27. - 29. Mai: Alexandria

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  • Bermes, Christian; Schafroth, Dario; Bouabdallah, Samir; Siegwart, Roland (2009) : Modular Simulation Model for Coaxial Rotary Wing MAVs: Proceedings of the 2nd International Symposium on Unmanned Aerial Vehicles 2009: 2nd International Symposium on Unmanned Aerial Vehicles 2009: Reno, 8. - 10. Juni

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  • Öttl, Sonja; Pfister, Joachim; Stettler, Niklaus; Studer, Markus; Wenk, Bruno (2008) : Garden Memory Goes Public. Ein ontologiebasiertes Informationssystem zur Gartendenkmalpflege In: Ockenfeld, Marlies: Verfügbarkeit von Informationen: 30. Online-Tagung der DGI, 60. Jahrestagung der DGI ; Frankfurt am Main, 15. bis 17. Oktober 2008 ; proceedings: Online-Tagung der DGI; Jahrestagung der DGI: Frankfurt am Main, 15.-17. Oktober. Deutsche Gesellschaft für Informationswissenschaft und Informationspraxis: Frankfurt am Main: Deutsche Gesellschaft für Informationswissenschaft und Informationspraxis (Tagungen der Deutschen Gesellschaft für Informationswissenschaft und Informationspraxis), S. 247-257

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  • Bermes, Christian; Leutenegger, Stefan; Bouabdallah, Samir; Schafroth, Dario; Siegwart, Roland (2008) : New design of the steering mechanism for a mini coaxial helicopter: EE International Workshop on Intelligent Robots and Systems (IROS): International Conference on Intelligent Robots and Systems: Nice, 22. - 26. September, S. 1236-1241

    Abstract: Whenever the realization of a swash plate mechanism is not feasible (e.g. due to miniaturization limitations), center of gravity steering is an interesting alternative to swash plate steering. We present an approach to describe the dynamic behavior of a coaxial micro helicopter steered by a center of gravity shifting mechanism. The mechanical design of an existing system is improved to increase mechanical robustness and steering quality. In parallel, a simulation model is developed and implemented. It is used to estimate the system response to steering inputs, and to compare center of gravity to swash plate steering. Experimental flight results show an improvement of the helicopter performance due to the mechanical redesign.

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  • Bermes, Christian; Leutenegger, Stefan; Bouabdallah, Samir; Siegwart, Roland (2008) : Design and Comparison of a Steering Mechanism for an Autonomous Coaxial Indoor Helicopter: Proceedings of The ASME International Symposium on Flexible Automation (ISFA): The ASME International Symposium on Flexible Automation (ISFA): Atlanta, 23. - 26. Juni

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  • Bermes, Christian; Sartori, Kevin; Schafroth, Dario; Bouabdallah, Samir; Siegwart, Roland (2008) : Control of a coaxial helicopter with center of gravity steering: Workshop Proceedings of SIMPAR 2008: International Conference on Simulation, Modeling, and Programming for Autonomous Robots: Venedig, 3. - 4. November, S. 492-500

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  • Bermes, Christian; Jacobs, Laurence J.; Kim, Jin-Yeon; Qu, Jianmin (2007) : Cumulative Second Harmonic Generation in Lamb Waves for the Detection of Material Nonlinearities In: Thompson, Donald O.; Chimenti, Dale E. (Hg.): Review of progress in quantitative nondestructive evaluation: Portland, 30. Juli - 4. August: 2006 (AIP conference proceedings), S. 177-184. Online verfügbar unter https://doi.org/10.1063/1.2717971, zuletzt geprüft am 06.05.2023

     

    Abstract: An understanding of the generation of higher harmonics in Lamb waves is of critical importance for applications such as remaining life prediction of plate‐like structural components. The objective of this work is to use nonlinear Lamb waves to experimentally investigate inherent material nonlinearities in aluminum plates. These nonlinearities, e.g. lattice anharmonicities, precipitates or vacancies, cause higher harmonics to form in propagating Lamb waves.The amplitudes of the higher harmonics increase with increasing propagation distance due to the accumulation of nonlinearity while the Lamb wavetravels along its path. Special focus is laid on the second harmonic, and a relative nonlinearity parameter is defined as a function of the fundamental and second harmonic amplitude. The experimental setup uses an ultrasonic transducer and a wedge for the Lamb wave generation, and laser interferometryfor detection. The experimentally measured Lamb wave signals are processed with a short‐time Fourier transformation (STFT), which yields the amplitudes at different frequencies as functions of time, allowing the observation of the nonlinear behavior of the material.The increase of the relative nonlinearity parameter with propagation distance as an indicator of cumulative second harmonic generation is shown in the results for the alloy aluminum 1100‐H14.

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  • Bermes, Christian; Schafroth, Dario; Bouabdallah, Samir; Siegwart, Roland (2007) : Aerodynamic Optimization, Dynamic Modeling and Overall Prototype Design for the muFly Autonomous Micro-Helicopter: International Symposium on Flying Insects and Robots: Flying Insects and Robots: Monte Verità, 12. - 17. August, S. 9-10

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  • Bouabdallah, Samir; Bermes, Christian; Schafroth, Dario; Siegwart, Roland (2007) : MuFly Project. The First Steps: International Symposium on Flying Insects and Robots: Flying Insects and Robots: Monte Verità, 12. - 17. August, S. 13-14

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  • Fenz, Susanne; Mathée, H.; Kreth, Gregor; Baddeley, David; Weiland, Y.; Schwarz-Finsterle, Jutta; Cremer, Christoph; Birk, Udo (2007) : Two-color intranuclear distance measurements of gene regions in human lymphocytes In: Wilson, Tony; Periasamy, Ammasi (Hg.): Confocal, Multiphoton, and Nonlinear Microscopic Imaging III: European Conference on Biomedical Optics: München, 17. - 21. Juni (SPIE Proceedings)

    DOI: http://proceedings.spiedigitallibrary.org/proceeding.aspx?doi=10.1117/12.727506 

    Abstract: The method of Spectral Precision Distance Microscopy (SPDM) has been used to determine distances between two FISH (Fluorescence-in situ-Hybridization)-labeled gene regions on chromosome 9. To this end we applied methods to correct for chromatic aberrations of the microscope optics alone and also of the sample induced aberrations due to mismatch of the refractive indices. Using a confocal microscope and a threshold based position determination algorithm, positions could be measured with an accuracy of about 65 nm inside of fixed cell nuclei. Distances obtained from the measurements have been verified using a 3D computer model of the cell nucleus. In principle, this SPDM approach could be combined with novel fluorescence microscopes to obtain structural information well below the optical resolution. At present the precision limit of the distance measurements is set by variations of the refractive index throughout the specimens.

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  • Fenz, Susanne; Mathée, Hans; Kreth, Gregor; Baddeley, David; Weiland, Yanina; Schwarz-Finstlerle, J.; Cremer, Christoph; Birk, Udo (2007) : Two-color intranuclear distance measurements of gene regions in human lymphocytes In: Wilson, Tony; Periasamy, Ammasi (Hg.): Confocal, multiphoton, and nonlinear microscopic imaging III: Proceedings of SPIE-OSA Biomedical Optics: European Conference on Biomedical Optics: München, 17. - 21. Juni: Bellingham, Wash.; Washington, D.C.: Optica Publishing Group (Proceedings of SPIE)

    Abstract: The method of Spectral Precision Distance Microscopy (SPDM) has been used to determine distances between two FISH (Fluorescence-in situ-Hybridization)-labeled gene regions on chromosome 9. To this end we applied methods to correct for chromatic aberrations of the microscope optics alone and also of the sample induced aberrations due to mismatch of the refractive indices. Using a confocal microscope and a threshold based position determination algorithm, positions could be measured with an accuracy of about 65 nm inside of fixed cell nuclei. Distances obtained from the measurements have been verified using a 3D computer model of the cell nucleus. In principle, this SPDM approach could be combined with novel fluorescence microscopes to obtain structural information well below the optical resolution. At present the precision limit of the distance measurements is set by variations of the refractive index throughout the specimens.

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  • Birk, Udo; Baddeley, David; Cremer, Christoph (2006) : Local protein/gene density measurements using SMI microscopy In: Gorecki, Christophe; Asundi, Anand K.; Osten, Wolfgang (Hg.): Optical Micro- and Nanometrology in Microsystems Technology: Photonics Europe: Strassburg, 3.-7. April (SPIE Proceedings)

    DOI: http://proceedings.spiedigitallibrary.org/proceeding.aspx?doi=10.1117/12.668023 

    Abstract: Spatially Modulated Illumination (SMI) microscopy was applied to determine changes of the local refractive index at discrete fluorescently labeled sites within the cell nucleus. We present measurements on polymerase II complexes, where we found a variation of the local refractive index of 1.38 - 1.55 (standard deviation interval) throughout the nucleus. This variability is not correlated to the accumulations and the extensions of the polymerase II complexes, which have been determined in a previous experiment.1 Local protein accumulations such as adherent transcriptionally active proteins could possibly contribute to such variations, as could also different compactions of the DNA fiber. Altogether, we present a method to precisely obtain a map of the local refractive index inside of cell nuclei, which provides another contrasting mechanism for visualizing sub cellular structures.

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  • Leutenegger, Tobias; Schlums, Dirk H.; Dual, Jürg (1999) : Structural testing of fatigued structures In: Wereley, Norman M.: Smart Structures and Materials 1999: Smart Structures and Integrated Systems: 1999 Symposium on Smart Structures and Materials: Newport Beach, 1. März (SPIE Proceedings), S. 987-997

    DOI: http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=982238 

    Abstract: The structural responses of beams and tubes is investigated in theory and experiment in order to locate and assess damage in the form of fatigue cracks. Crack length measurements are performed in transversely vibrating beams by determining the resonant frequency, which is stabilized through a phase locked loop. Cracks are initiated and propagate from the notch of the structure which is vibrating at resonance. The frequency in relation to the crack length is modeled including the nonlinearity effect due to closing of the crack. Fatigue tests were also carried out with piezoelectrically excited microstructures.

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  • Öttl, Sonja; Streiff, Daniel; Stettler, Niklaus; Studer, Martin : Aufbau einer Testumgebung zur Ermittlung signifikanter Parameter bei der Ontologieabfrage In: Ockenfeld, Marlies: Semantic Web & Linked Data: Elemente zukünftiger Informationsinfrastrukturen: 62. Jahrestagung der DGI: 1. DGI-Konferenz: Frankfurt am Main, 7.-9. Oktober. Deutsche Gesellschaft für Informationswissenschaft und Informationspraxis, S. 21-32

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  • Schafroth, Dario; Bermes, Christian; Bouabdallah, Samir; Siegwart, Roland : Micro Helicopter Steering: Review and Design for the muFly Project: 2008 IEEE/ASME International Conference on Mechtronic and Embedded Systems and Applications: International Conference on Intelligent Robots and Systems: Beijing, 12. - 15. Oktober: 2008, S. 216-221

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  • Darrell, Alexander; Marias, Kostas; Brady, Michael; Meyer, Heiko; Birk, Udo; Ripoll, Jorge : Noise reduction in fluorescence Optical Projection Tomograph: 2008 IEEE International Workshop on Imaging Systems and Techniques: Chania, 10. - 12. September: 2008

    Abstract: Optical Projection Tomography (OPT) suffers from additive CCD detector noise. This paper investigates the nature of the CCD detector noise for an OPT setup. The CCD detector noise is found to be described well by an intensity dependent zero-mean Gaussian distribution. A method of reducing the effect of noise in fluorescence OPT reconstructions is discussed. The results of the noise reduction are demonstrated using both artificial scenes created with fluorescent microspheres and real auto-fluorescence OPT projections of the cuticle of the amphipod crustacean Parhyale hawaiensis.

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  • Darrell, Alexander; Meyer, H.; Birk, Udo; Marias, Kostas; Brady, Michael; Ripoll, Jorge : Maximum likelihood reconstruction for fluorescence Optical Projection Tomography: 2008 8th IEEE International Conference on BioInformatics and BioEngineering: Athen, 8. - 10. Oktober: 2008

    Abstract: Tomographic reconstruction of fluorescence optical projection tomography (OPT) data is usually performed using the standard filtered back projection (FBP) algorithm. However, there are several physical aspects of fluorescence OPT that pose major challenges for the FBP algorithm. These include blurring, and the fact that for an isotropically emitting point source (or fluorophore), the power received by an objective aperture decreases with the inverse square of the distance to the source. These two effects are shown to result in qualitative and quantitative inaccuracies in fluorescence OPT reconstructions obtained using standard FBP. A model of image formation is developed which includes the effects of isotropic emission and blurring. The model is used to calculate a probabilistic system matrix for use in the maximum likelihood expectation maximisation algorithm, which leads to reconstructions that are both qualitatively superior and quantitatively correct.

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  • Merbold, Hannes; Wahl, Ulrich; Stosky, Steven : Laser-Based Oxygen Monitoring in Waste Incineration Facilities: Benefits and Challenges: Advanced Photonics 2014: Proceedings: Nonlinear Photonics: Barcelona, 27. - 31. Juli: 2015

    Abstract: Oxygen measurements using tunable diode laser absorption spectroscopy were performed at a full scale waste incineration facility. A comparative analysis to a reference method allowed identifying benefits and challenges inherent to the laser method.

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  • van Mechelen, J. L. M.; Kuzmenko, A. B.; Merbold, Hannes : High precision material characterization method using THz spectroscopy: 39th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz): Tucson, 14. - 19. September: 2014

    Abstract: We propose a novel THz material analysis approach which consists of a combination of a stratified dispersive model, an appropriate measurement configuration and a time-domain based fitting procedure. The measurement configuration is modeled as a stratified system where for each layer the light-matter interaction is realistically described. The method is illustrated for the industrial quality control of (coated) paper sheets and is shown to give highly accurate results in humid air and irrespective of the position of the reference mirror in reflection.

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  • Merbold, Hannes; Weber, Yannik; Murk, Axel; Feurer, Thomas : Sensing the Dielectric Properties of Metals at THz Frequencies Using Inverse Symmetry Broken Metamaterial: Advanced Photonics 2015: Proceedings: Optical Sensors: Boston, 27. Juni - 1. Juli: 2015

    Abstract: Positive and inverse, asymmetric, double split-ring resonator structures are analyzed experimentally and numerically. The structures exhibit very sharp dark resonances which allow probing the dielectric properties of metals at THz frequencies.

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  • Eberhart, Martin F.; Löhle, Stefan; Zander, Fabian; Merbold, Hannes; Murk, Axel; Merli, Stefan : Electromagnetic Wave Transmission through Lightweight Carbon Phenolic Ablator. Microwave to Infrared Frequencies: 46th AIAA Thermophysics Conference: Washington, 13. - 17. Juni: 2016

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  • van Mechelen, J. L. M.; Maas, D. J. H. C.; Merbold, Hannes : Paper sheet parameter determination using terahertz spectroscopy: 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz): Kopenhagen, 25. - 30. September: 2016

    Abstract: Using THz spectroscopy, we show how to uniquely determine parameters for industrial quality control of paper sheets. We carry out measurements within the industrial setting: no averaging, fast acquisition in ambient conditions, and quasi-real-time analysis. Paper parameters are extracted using a combination of statistical evaluation and physical interpretation of the light-matter interaction. We show that THz spectroscopy offers additional value as compared to currently used industrial sensors.

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  • Merbold, Hannes; Maas, D. J. H. C.; van Mechelen, J. L. M. : Multiparameter sensing of paper sheets using terahertz time-domain spectroscopy. Caliper, fiber orientation, moisture, and the role of spatial inhomogeneity: 2016 IEEE SENSORS: Orlando, 10. Oktober - 3. November: 2016, S. 1-3
  • Jacobson, Christopher David; Capol, Corsin; Bügler, Tanja; Staudt, Yves; Derungs, Robin (2023) : Einsatz und Potenzial künstlicher Intelligenzim Tourismus. Verhaltensprogrnosen In: Bieger, Thomas; Beritelli, Pietro; Laesser, Christian (Hg.): Alpiner Tourismus in disruptiven Zeiten: Berlin: Erich Schmidt Verlag (Schweizer Jahrbuch für Tourismus), S. 265-278

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  • Capol, Corsin; Jacobson, Christopher David; Balestra, Stefano; Bügler, Tanja; Staudt, Yves; Siegrist, Chantal; Iten, Marc-Alexander (2022) : Personalallokation und -planung für das Immobilienmanagement im Tourismus In: Bieger, Thomas; Beritelli, Pietro; Laesser, Christian (Hg.): Krisenbewältigung und digitale Innovationen im alpinen Tourismus: Berlin: Erich Schmidt Verlag (Schweizer Jahrbuch für Tourismus), S. 131-146

    Abstract: In Zusammenarbeit mit der Weissen Arena AG haben die AutorInnen der FH Graubünden (Corsin Capol, Christopher Jacobson, Stefano Balestra, Tanja Bügler, Yves Staudt, Chantal Siegrist und Marc-Alexander Iten) ein durch maschinelles Lernen optimiertes System entwickelt, das zuverlässig Einsätze beispielsweise für das Reinigungspersonal prognostizieren kann.

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  • Capol, Corsin; Jacobson, Christopher David; Balestra, Stefano; Bügler, Tanja; Staudt, Yves (2022) : Personalallokation und -planung für das Immobilienmanagement im Tourismus (PIT) In: Forster, Michael; Alt, Sharon; Hanselmann, Marcel; Deflorin, Patricia (Hg.): Digitale Transformation an der Fachhochschule Graubünden: Case Studies aus Forschung und Lehre: Chur: FH Graubünden Verlag, S. 101-110. Online verfügbar unter https://www.fhgr.ch/fh-graubuenden/ueber-die-fh-graubuenden/wofuer-stehen-wir/digitalisierung/digitalisierungswissen-fuer-graubuenden/#c15147, zuletzt geprüft am 20.01.2023

     

    Abstract: Die Fachhochschule Graubünden (FHGR) hat zusammen mit der Weisse Arena Gruppe und LAAX Homes AG einen Forschungsprototyp für die Personalallokation und -planung für das Immobilienmanagement im Tourismus entwickelt. Im Anschluss an die Modellierung der Personalstrukturdaten und der Übernachtungsangebote wurde ein AI Constraint Satisfaction Solver für die Personalallokation (Planung von Reinigungsteams für einen konkreten Tag) durch das Institut für Photonics und Robotics (IPR) entwickelt. Ebenfalls wurden die Einflussfaktoren auf die Vorbuchungs- und Aufenthaltsdauer anhand maschinellen Lernens durch das Institut für Tourismus und Freizeit (ITF) erforscht und das Verhalten von Eigentümern und Gästen analysiert. Basierend auf den Erkenntnissen der Tourismusforschung wurde ein Modell zur Vorhersage der Anzahl an Abreisen durch das IPR implementiert. Durch eine agile Vorgehensweise wurde der Forschungsprototyp früh getestet und in die Systemlandschaft der Weisse Arena Gruppe integriert. Mit einer vorausschauenden und technologieunterstützten Vorhersage des Personalbedarfs kann das benötigte Reinigungspersonal vorzeitig (den zu reinigenden Immobilien) zugeordnet werden. Durch die Planungssicherheit seitens der Weisse Arena Gruppe und der LAAX Homes AG können Engpässe frühzeitig erkannt und entsprechende Massnahmen definiert werden. Dies hat einen Einfluss auf die Zufriedenheit von Mitarbeitenden. Die Ferienimmobilien können durch die Personalallokation effizient durch das Reinigungspersonal angefahren und gereinigt werden.

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  • Birk, Elisabeth; Birk, Udo; Birk, Hanne (2022) : Online Teaching. Überlegungen zu digitalem Lehren und Lernen In: Forster, Michael; Alt, Sharon; Hanselmann, Marcel; Deflorin, Patricia (Hg.): Digitale Transformation an der Fachhochschule Graubünden: Case Studies aus Forschung und Lehre: Chur: FH Graubünden Verlag, S. 87-100. Online verfügbar unter https://www.fhgr.ch/fh-graubuenden/ueber-die-fh-graubuenden/wofuer-stehen-wir/digitalisierung/digitalisierungswissen-fuer-graubuenden/#c15147, zuletzt geprüft am 20.01.2023

     

    Abstract: Digitale Lehre bietet vielfältige, medienspezifische Möglichkeiten, um Lehrinhalte zu vermitteln. Allerdings ist die didaktische und technische Umsetzung oftmals eine Herausforderung. Wir diskutieren Vor- und Nachteile der digitalen Lehre anhand von transdisziplinären Beispielen aus der Lehrpraxis.

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  • Jacobson, Christopher David; Capol, Corsin; Moser, Peter (2019) : Aktivitätsbasiertes Online-Gruppenbuchungstool In: Bieger, Thomas; Beritelli, Pietro; Laesser, Christian (Hg.): Neue Technologien und Kommunikation im alpinen Tourismus: Berlin: Erich Schmidt Verlag (Schweizer Jahrbuch für Tourismus), S. 149-164

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  • Birk, Udo; Best, Gerrit; Amberger, Roman; Cremer, Christoph (2017) : Super-Resolution Microscopy. Interference and Pattern Techniques In: Kubitscheck, Ulrich: Fluorescence Microscopy: From Principles to Biological Applications: Weinheim: Wiley-VCH, S. 291-319

    Abstract: Fluorescence microscopy techniques using patterned illumination light offer the opportunity to extract high-resolution object information beyond the conventional resolution limit. This chapter describes in detail two widefield methods that apply interference of the excitation light to make high-resolution object information accessible. These are structured illumination microscopy (SIM) (also referred to as patterned excitation microscopy, PEM) and spatially modulated illumination (SMI). In SIM, the object is illuminated with a periodic illumination pattern. This pattern is used in order to manipulate the object's spatial frequencies. Two methods to spatially modulate the excitation intensity in SIM are common: two-beam interference, also called fringe projection, and three-beam interference, the so-called grid projection. The secondary focus of this chapter is on the less common method of SMI, where two opposing objective lenses are used to generate a high-frequency interference pattern along the optical axis. The SMI method is used to measure the size of nanostructures with great precision.

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  • Grossmann, C.; Schwarz-Finsterle, Jutta; Schmitt, Eberhard; Birk, Udo; Hildenbrand, Georg; Cremer, Christoph; Trakhtenbrot, Luba; Hausmann, Michael (2010) : Variations of the spatial fluorescence distribution in ABL gene chromatin domains measured in blood cell nuclei by SMI microscopy after COMBO – FISH labelling In: Méndez-Vilas, Antonio; Díaz, J. (Hg.): Microscopy: Science, technology, applications and education: Badajoz: Formatex (Formatex Microscopy Series), S. 688-695

    Abstract: Despite investigations of the nuclear architecture of the genome, the true 3D nanoarchitecture of small chromatin domains and its correlation to epigenetic control mechanisms are still not sufficiently known. Reasons for this are the lack of nanostructure conserving labelling techniques as well as practical limitations in 3D fluorescence microscopy with high optical resolution (100 nm and below). The present study was initiated as an attempt to overcome these methodological shortcomings. As a model case we compared the spatial extension of fluorescence of chromatin domains in ABL gene regions in blood cells (BC) of different Chronic Myelogenous Leukemia (CML) patients with BCR/ABL fusion on the Philadelphia chromosome (Ph) and in lymphocytes of a healthy donor and a Prader-Willi syndrome patient by Spatially Modulated Illumination (SMI) microscopy after specific labelling using COMBinatorial Oligo Fluorescence In Situ Hybridization (COMBO–FISH). Volumes and compaction ratios of interactively identified ABL chromatin domains were determined under the assumption of a compact spherical fluorescence distribution. Significant differences were found between the domain size values of the labelled sites of Ph+ BC nuclei of CML patients and of Ph- BC nuclei of a CML patient after successful chemotherapy (imatinib mesylate (STI) treatment). Differences were also significant between BC of all CML patients and lymphocyte control preparations. These results show the feasibility of COMBO-FISH in combination with SMI microscopy.

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  • Birk, Udo; Baddeley, David; Cremer, Christoph (2008) : Nanosizing by Spatially Modulated Illumination (SMI) Microscopy and Applications to the Nucleus In: Hancock, Ronald: The Nucleus: Volume 2: Chromatin, Transcription, Envelope, Proteins, Dynamics, and Imaging: Totowa: Humana Press

    Abstract: In this chapter we present the method of spatially modulated illumination (SMI) microscopy, a (far-field) fluorescence microscopy technique featuring structured illumination obtained via a standing wave field laser excitation pattern. While this method does not provide higher optical resolution, it has been proven a highly valuable tool to access structural parameters of fluorescently labeled macromolecular structures in cells. SMI microscopy has been used to measure relative positions with a reproducibility of <2 nm between fluorescing objects. Among others, we have measured size distributions of protein clusters with an accuracy much better than the resolution achievable e.g. in confocal microscopy. The advantages of the SMI microscope over other (ultra-)high resolution light microscopes are its easy sample preparation and microscope handling as well as the comparably fast acquisition times and large fields of view.

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  • Birk, Udo; Upmann, I.; Toomre, D.; Wagner, C.; Cremer, Christoph (2007) : Size Estimation of Protein Clusters in the Nanometer Range by Using Spatially Modulated Illumination Microscopy In: Méndez-Vilas, Antonio; Díaz, J. (Hg.): Modern research and educational topics in microscopy: Badajoz: Formatex (Formatex Microscopy Series), S. 272-279

    Abstract: A major goal of modern cell biology is the improved understanding of the three dimensional nanostructure of cellular macromolecule complexes, a goal for which a variety of research tools have been developed. Here, we describe the potential of Spatially Modulated Illumination (SMI) microscopy, a far field light optical method, to study the axial extent of fluorescently labeled protein clusters in the membrane of PtK2 cells. This is done by comparison of experimental SMI-data with the predictions of “virtual SMI-microscopy” calculations for an assumed dye distribution. Previous SMI investigations have shown that object sizes down to a few tens of nanometers can be extracted, and the method has been applied in a biological setting to determine the axial extents of nuclear nanostructures. Using these novel far field light microscopy tools at 488 nm excitation wavelength, the extension of GPI-anchored protein clusters perpendicular to the cell membrane was estimated to be (69±18) nm.

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  • Leutenegger, Tobias (2023): «Proof of Brain Gain». In: Wissensplatz, S. 14-15. Online verfügbar unter https://www.fhgr.ch/fh-graubuenden/medien-und-oeffentlichkeit/publikationen/wissensplatz/februar-2023/, zuletzt geprüft am 18.02.2023

     

    Abstract: Landquart, Forum Ried, 22. September 2022: Die Photonics-Absolvierenden der Fachhochschule Graubünden erhalten vom Rektor und ihrem Studienleiter Tobias Leutenegger ihre wohlverdienten Bachelordiplome. Stolz halten eine Photonics-Ingenieurin und neun Photonics-Ingenieure die Urkunden in ihren Händen. Hurra, geschafft! Studium erfolgreich abgeschlossen – und jetzt?

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  • von Hase, Johann; Birk, Udo; Humbel, Bruno; Liu, Xiaomin; Failla, Antonio Virgilio; Cremer, Christoph (2023): Ring Array Illumination Microscopy. Combination of Super-Resolution with Large Field of View Imaging and long Working Distances. In: bioRxiv. DOI: 10.1101/2023.09.05.555896

    DOI: RemoteUri 

    Abstract: Here we present a novel fluorescence microscopy concept which enables a direct integration of Super-Resolution Microscopy (SRM) approaches (SIM/Nanosizing, STED, SMLM, MINFLUX, SIMFLUX) into microscopy systems with working distances (WD) up to the multicentimeter range while still allowing nanometer scale resolution at selected sites. This becomes possible by a "leftsynthetic aperture"right illumination mode with multiple, constructively interfering excitation beams positioned in a "leftRing-Array"right arrangement around a beam free interior zone containing instrumentation involved in complementary imaging modes. The feasibility of such a direct correlative microscopy method is validated by extensive numerical simulations; on the basis of these calculations, experimental implementation options are discussed. Such "leftRing Array"right illumination modes may be useful for various correlative microscopy methods, such as a direct combination of correlative light and electron microscopy in the same device (dCLEM); or a direct combination of low NA/large field-of-view widefield microscopy and super-resolution of selected sites in the same device (direct Correlative Opical Microscopy/dCOLM). Ring-Array supported correlative microscopy modes will open novel imaging perspectives in a variety of disciplines, from material sciences to biomedical applications.

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  • Leutenegger, Tobias (2022): Mission «Alpine Drone Rescue» oder «Rette mich!». In: Wissensplatz, S. 6-7. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/februar-2022/, zuletzt geprüft am 10.02.2022

     

    Abstract: Ein herrlicher Herbsttag im schönen Graubünden – der Himmel stahlblau, die Luft klar, aber schon etwas kühl, und das Ziel in Reichweite. Mit den Kolleginnen und Kollegen brechen wir auf zur nächsten Etappe. Wir fühlen uns fit und kommen gut voran. Der Schwierigkeitsgrad ist fordernd, aber wir sind ja auch keine Anfängerinnen und Anfänger mehr. Für einen kurzen Moment sind wir nicht konzentriert und alles geht sehr schnell: Ein Tritt ins Leere, der freie Fall, alles dreht sich und die potenzielle Energie wird in kinetische Energie umgewandelt. Wir warten auf den Aufprall und denken: Wars das?

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  • Cremer, Christoph; Birk, Udo (2022): Spatially modulated illumination microscopy. Application perspectives in nuclear nanostructure analysis. In: Philosophical transactions. Series A. Mathematical, physical, and engineering sciences 380. Online verfügbar unter https://doi.org/10.1098/rsta.2021.0152, zuletzt geprüft am 17.02.2022

     

    Abstract: Thousands of genes and the complex biochemical networks for their transcription are packed in the micrometer sized cell nucleus. To control biochemical processes, spatial organization plays a key role. Hence the structure of the cell nucleus of higher organisms has emerged as a main topic of advanced light microscopy. So far, a variety of methods have been applied for this, including confocal laser scanning fluorescence microscopy, 4Pi-, STED- and localization microscopy approaches, as well as (laterally) structured illumination microscopy (SIM). Here, we summarize the state of the art and discuss application perspectives for nuclear nanostructure analysis of spatially modulated illumination (SMI). SMI is a widefield-based approach to using axially structured illumination patterns to determine the axial extension (size) of small, optically isolated fluorescent objects between less than or equal to 200 nm and greater than or equal to 40 nm diameter with a precision down to the few nm range; in addition, it allows the axial positioning of such structures down to the 1 nm scale. Combined with SIM, a three-dimensional localization precision of less than or equal to 1 nm is expected to become feasible using fluorescence yields typical for single molecule localization microscopy applications. Together with its nanosizing capability, this may eventually be used to analyse macromolecular complexes and other nanostructures with a topological resolution, further narrowing the gap to Cryoelectron microscopy. This article is part of the Theo Murphy meeting issue 'Super-resolution structured illumination microscopy (part 2)'.

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  • Bermes, Christian (2022): Grosse Hoffnungen ins neue Fachhochschulzentrum. In: Wissensplatz, S. 30-31. Online verfügbar unter https://www.fhgr.ch/fh-graubuenden/medien-und-oeffentlichkeit/publikationen/wissensplatz/september-2022/, zuletzt geprüft am 23.09.2022

     

    Abstract: Mit dem Start der Studienrichtung Mobile Robotics (MR) im September 2020 hat auch der Aufbau des Mobile Robotics Lab an der Fachhochschule Graubünden begonnen. Nach wie vor verfolgen wir das Ziel, einen physischen Ort an der Fachhochschule zu schaffen, an dem gleichzeitig gelehrt, geforscht und diskutiert werden kann. Ich möchte hier kurz berichten, was wir diesbezüglich bereits erreicht haben und welche Chancen das Fachhochschulzentrum hierfür bieten kann.

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  • Hauser-Ehninger, Ulrich (2021): Mit dem Hard- und Softwarespezialisten im Labor. In: Wissensplatz, S. 22-23. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/februar-2021/, zuletzt geprüft am 12.02.2021

     

    Abstract: Begleitet man Gion-Pol Catregn eine Woche lang bei seiner Arbeit, so zeigt sich ein Regenbogen an Aktivitäten. Diese erfordern eine ebenso grosse Palette an Kompetenzen. Der 48-Jährige ist Dozent am Institut für Photonics und ICT. Einen Grossteil seiner Arbeit erledigt er im Photonics-Labor der FH Graubünden.

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  • Beyer, Thomas; Bailey, Dale L.; Birk, Udo; Buvat, Irene; Catana, Ciprian; Cheng, Zhen; Fang, Qiyin; Giove, Federico; Kuntner, Claudia; Laistler, Elmar; Moscato, Francesco; Nekolla, Stephan G.; Rausch, Ivo; Ronen, Itamar; Saarakkala, Simo; Thielemans, Kris; van Elmpt, Wouter; Moser, Ewald (2021): Medical Physics and Imaging. A Timely Perspective. In: Frontiers in Physics 9. Online verfügbar unter https://doi.org/10.3389/fphy.2021.634693, zuletzt geprüft am 14.05.2021

     

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  • Hauser-Ehninger, Ulrich (2021): Wie die Distanz eine gemeinsame Problemlösung ermöglicht. In: Wissensplatz, S. 12-13. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/september-2021/, zuletzt geprüft am 10.09.2021

     

    Abstract: Das Photonics- und Mobile-Robotics-Studium lebt von gemeinsamen praktischen Übungen. Und so stellte sich bald nach Beginn der Coronapandemie die Frage, wie im Distanzunterricht über Videokonferenzsysteme praktische Erfahrungen für die Studierenden im Bereich Elektronik ermöglicht werden könnten. In kurzer Zeit gelang es, aus der Not eine Tugend zu machen und ein Übungskit zu entwickeln, mit dem die Studierenden zuhause arbeiten können. Die Lösung brachte Überraschendes zu Tage: Distanzunterricht auf praktischer Ebene kann sogar Vorteile gegenüber einem Laborbetrieb in Präsenz haben.

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  • Reiss, Simon; Lottner, Thomas; Ozen, Ali Caglar; Polei, Stefan; Bitzer, Andreas; Bock, Michael (2021): Analysis of the RF Excitation of Endovascular Stents in Small Gap and Overlap Scenarios Using an Electro-Optical E-field Sensor. In: IEEE Transactions on Biomedical Engineering 68, S. 783-792. DOI: 10.1109/TBME.2020.3009869

    Abstract: OBJECTIVE To assess the effect of the electro-magnetic coupling of endovascular stents on their RF heating potential in MRI. METHODS A custom-built electro-optic E-field probe is used to perform measurements of the scattered E-field at a distance of 2 mm to stent samples with submillimeter resolution. Various combinations of stent lengths are measured at 124 MHz (3T MRI Larmor frequency) with varying gap and overlap between the stents, with and without stent coating, and with distilled water and saline solution as surrounding media. The results are compared to theoretically derived E-field distributions. RESULTS At an overlap of 10 mm the E-field pattern of two stents collapses to a single dipole indicating excellent coupling between the stents. E-field intensities substantially increase/decrease up to 5-fold/2.5-fold if the total length of the two combined stents is closer/further away from the resonance length of the single stents. Stent coating and conductivity of the surrounding medium strongly influence the E-field patterns of overlapping stents. Measured and calculated E-field patterns are in good agreement. CONCLUSION Electro-optic E-field measurements are a valuable tool for RF safety assessments in both single as well as coupled stents. SIGNIFICANCE RF induced heating of single stents during MRI has been extensively studied. However, in clinical practice often two or more stents are implanted in close proximity which can substantially change the pattern of the scattered electric fields and the localization and intensity of hot spots. In this study a detailed assessment of the coupling of stents during RF excitation is given.

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  • Lottner, Thomas; Reiss, Simon; Bitzer, Andreas; Bock, Michael; Caglar Ozen, Ali (2021): A Transfer Function Measurement Setup With an Electro-Optic Sensor for MR Safety Assessment in Cascaded Media. In: IEEE Transactions on Electromagnetic Compatibility 63, S. 662-672. DOI: 10.1109/TEMC.2020.3040756

    Abstract: This article introduces a transfer function (TF) measurement setup for cascaded media (CM) and demonstrates that the full immersion of an implant in a lossy medium might result in an underestimation of the RF-induced heating compared to partial immersion. A CMTF measurement setup was constructed using medium-specific local electric field sources and electro-optical sensor (EOS). TFs of bare and insulated wire samples were measured in the CM air/saline. Finite-difference time-domain (FDTD) simulations were implemented using a reciprocal approach with a monopole excitation source as well as a piecewise plane wave excitation method. As a theoretical guideline for understanding the CM behavior of the devices, an analytical model based on the buried wire models was derived. CMTFs agree with good precision between FDTD simulations, analytical modeling, and the EOS measurements. Measured TFs were calibrated and validated similar to ISO/TS 10974:Ed.2. Calculated tip SAR values under uniform incident field show an increase up to a factor of 5.7 for partially immersed wires compared to the full immersion. On average, FDTD-based TFs overestimate SAR by 25% compared to measurement-based TFs. As safety assessments for fully immersed implant leads or devices might not represent the worst-case scenario, single-medium assessments might underestimate the RF-induced heating.

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  • Janett, Patrik (2020): Zum Wohle der Konsumenten und der Umwelt. Fachhochschule Graubünden bietet als Dienstleistung Messungen nach Topten-Anforderungen. In: Polyscope 52, S. 20-21. Online verfügbar unter https://www.polyscope.ch/archiv/2020/01-02/, zuletzt geprüft am 14.02.2020

     

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  • Leutenegger, Tobias (2020): Der Murmeltier-Wettkampf. In: Wissensplatz, S. 12-13. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/februar-2020/, zuletzt geprüft am 28.02.2020

     

    Abstract: Eine praxisorientierte Ausbildung ist einer der wichtigsten Aspekte für die erfolgreiche Vorbereitung der Studierenden des Bachelorstudiengangs Photonics auf die Arbeitswelt. Mit dem Projekt «Murmeltier», einer Art Kugelbahn, waren die Absolventinnen und Absolventen im letzten Jahr stark gefordert. Sie bewiesen ihrem Studienleiter jedoch, dass sie bereit sind für die Arbeitswelt.

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  • Roebrock, Philipp (2020): Neuer Studiengang spürt dem Roboter nach. In: Wissensplatz, S. 10-11. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/februar-2020/, zuletzt geprüft am 28.02.2020

     

    Abstract: Mobile Roboter sind ein Technologietrend unserer Zeit. Sie sind aus vielen Bereichen nicht mehr wegzudenken – etwa der Logistik, der Vermessung und Erkundung oder auch dem Servicebereich. Aber was sind mobile Roboter überhaupt und warum lohnt es sich, sich mit ihnen zu beschäftigen?

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  • Schneckenburger, H.; Richter, V.; Gelleri, M.; Ritz, S.; Vaz Pandolfo, R.; Schock, F.; Hase, V. J.; Birk, Udo; Cremer, C. (2020): High-resolution deep view microscopy of cells and tissues. In: Quantum Electronics 50, S. 2-8. Online verfügbar unter http://dx.doi.org/10.1070/QEL17204, zuletzt geprüft am 31.01.2020

     

    Abstract: Methods, experimental setups and perspectives of threedimensional deep view imaging microscopy of cell or tissue samples are reported. Preliminary biophysical and clinically relevant examples are presented.

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  • Hauser-Ehninger, Ulrich (2020): Einblicke: ein Sabbatical in Georgien. In: Wissensplatz, S. 10-11. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/september-2020/, zuletzt geprüft am 10.09.2020

     

    Abstract: Ein Sabbatical voller spannender Eindrücke, faszinierender Land schaften und herzlicher Begegnungen – Ulrich Hauser-Ehninger, Dozent am Institut für Photonics und ICT (IPI) der FH Graubünden, reiste mit seiner Familie im Herbst 2019 für fünf Monate nach Georgien. Dort unterrichtete er auch an der Ilia-University in Tbi lisi und war fasziniert von der Andersartigkeit dieses Landes.

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  • Birk, Udo (2019): Schlaue Helfer dank Embedded Vision. In: Aktuelle Technik 2019. Online verfügbar unter https://aktuelletechnik.blverlag.ch/schlaue-helfer-dank-embedded-vision/

     

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  • Birk, Udo (2019): Super-Resolution Microscopy of Chromatin. In: Genes 10. Online verfügbar unter https://doi.org/10.3390/genes10070493, zuletzt geprüft am 14.02.2020

     

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  • Birk, Udo (2019): Wenn der Körper das Passwort ist. In: Polyscope 2019, S. 30-31. Online verfügbar unter https://www.polyscope.ch/archiv/2019/19/wenn-der-koerper-das-passwort-ist/

     

    Abstract: Gesichtserkennung ist ein aktuelles Forschungsthema, nicht nur in der Neurowissenschaft. Mit modernen lichtbasierten Technologien kann man Gesichtserkennung auch auf elektronischen Geräten wie Handys realisieren. Zusammen mit dem Fingerabdruckscanner betreten wir mit der Gesichtserkennung ein neues Zeitalter der digitalen Sicherheit: Entweder ich benutze ein Passwort, oder mein Körper ist das Passwort.

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  • Birk, Udo; Cremer, Christoph; von Hase, Johann (2019): Lens Free Super-Resolution Microscopy. Distributed Aperture Illumination Allows Large Working Distances. In: Imaging & Microscopy 2019, S. 23-25. Online verfügbar unter https://www.imaging-git.com/magazine/imaging-microscopy-issue-42019

     

    Abstract: High-resolution microscopy methods typically use objective lenses with large numerical apertures, i.e. low working distances (WD) in the range of 0.2 mm. This impedes its application to thick transparent specimens, or to objects with large topographical differences. To extend high-resolution microscopy also to whole tissues and to the material sciences, lens free microscope systems allowing WDs up to the multicentimeter range and an optical resolution down to the nanometer range may be constructed.

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  • Caviezel, Petra; Merbold, Hannes (2019): 3D-Time-of-Flight-Kameras für Unterwasserapplikationen. In: Wissensplatz, S. 16-17. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/februar-2019/, zuletzt geprüft am 14.02.2019

     

    Abstract: Durch die Verwendung von Leuchtdioden im sichtbaren Bereich konnten 3D-Time-of-Flight-Kameras für den Einsatz in Unterwasserumgebungen optimiert werden. Dies ermöglicht es, Bewegungsabläufe in Pool-Umgebungen mit Gegenstandsweiten im Meterbereich zeitlich und in drei räumlichen Dimensionen aufzulösen.

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  • Janett, Patrik (2019): Etikettenschwindel. In: Elektrotechnik

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  • Neumann, Jan; Ziegler, Kira; Gelléri, Márton; Fröhlich-Nowoisky, Janine; Liu, Fobang; Bellinghausen, Iris; Schuppan, Detlef; Birk, Udo; Pöschl, Ulrich; Cremer, Christoph; Lucas, Kurt (2019): Nanoscale distribution of TLR4 on primary human macrophages stimulated with LPS and ATI. In: Nanoscale 11, S. 9769-9779. Online verfügbar unter http://dx.doi.org/10.1039/C9NR00943D, zuletzt geprüft am 20.02.2020

     

    Abstract: Toll-like receptor 4 (TLR4) plays a crucial role in the recognition of invading pathogens. Upon activation by lipopolysaccharides (LPS), TLR4 is recruited into specific membrane domains and dimerizes. In addition to LPS, TLR4 can be stimulated by wheat amylase-trypsin inhibitors (ATI). ATI are proteins associated with gluten containing grains, whose ingestion promotes intestinal and extraintestinal inflammation. However, the effect of ATI vs. LPS on the membrane distribution of TLR4 at the nanoscale has not been analyzed. In this study, we investigated the effect of LPS and ATI stimulation on the membrane distribution of TLR4 in primary human macrophages using single molecule localization microscopy (SMLM). We found that in unstimulated macrophages the majority of TLR4 molecules are located in clusters, but with donor-dependent variations from ∼51% to ∼75%. Depending on pre-clustering, we found pronounced variations in the fraction of clustered molecules and density of clusters on the membrane upon LPS and ATI stimulation. Although clustering differed greatly among the human donors, we found an almost constant cluster diameter of ∼44 nm for all donors, independent of treatment. Together, our results show donor-dependent but comparable effects between ATI and LPS stimulation on the membrane distribution of TLR4. This may indicate a general mechanism of TLR4 activation in primary human macrophages. Furthermore, our methodology visualizes TLR4 receptor clustering and underlines its functional role as a signaling platform.

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  • Birk, Udo (2018): Gesichtserkennung statt PIN?. In: Swiss Engineering STZ 115

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  • Capol, Corsin; Jacobson, Christopher David; Moser, Peter (2018): Wissen praxisorientiert umsetzen – in Kooperationen. In: Wissensplatz, S. 26-27. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/september-2018/, zuletzt geprüft am 07.02.2018

     

    Abstract: Ein Team der HTW Chur entwickelte in einem interdisziplinären Forschungsprojekt gemeinsam mit dem Hauptumsetzungspartner Graubünden Ferien ein Online-Buchungstool für Gruppenreisen. Dabei wurde nicht nur auf dem Wissen verschiedener Institutionen aufgebaut – dieses Wissen wurde auch gemeinsam vertieft und im Buchungstool praxisorientiert umgesetzt.

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  • Catregn, Gion-Pol (2018): Objektüberwachung im Museum mittels Laserscanner. In: Wissensplatz, S. 16-178. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/september-2018/, zuletzt geprüft am 07.02.2018

     

    Abstract: Für seine neu gestalteten Räumlichkeiten suchte das Museum für Gestaltung Zürich ein Objektsicherungssystem, welches sowohl den funktionalen als auch den optischen Anforderungen eines Design-Museums gerecht wird. Die Photonics-Experten der HTW Chur konnten diese Herausforderung mit einem «unsichtbaren Vorhang» meistern.

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  • Cremer, Christoph; Szczurek, Aleksander; Strickfaden, Hilmar; Birk, Udo; Cremer, Marion; Cremer, Thomas (2018): Der Zellkern - eine Stadt in der Zelle, Teil 2. In: Biologie in unserer Zeit 48, S. 45-53. Online verfügbar unter https://doi.org/10.1002/biuz.201810640, zuletzt geprüft am 07.05.2023

     

    Abstract: Im zweiten Teil des Beitrags zur Zellkernarchitektur beschreiben wir die bahnbrechenden Möglichkeiten der superauflösenden Fluoreszenzmikroskopie (Nanoskopie) und neuer molekularbiologischer Verfahren zur Erforschung der Struktur von Chromatindomänen im Nanometer-Maßstab und ihrer räumlichen Anordnung zu größeren Aggregaten. Neue experimentelle Daten und Modelle sprechen für eine entscheidende Rolle dieser Strukturen für die Genregulation und andere Funktionen des Zellkerns.

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  • Szczurek, Aleksander; Birk, Udo; Knecht, Hans; Dobrucki, Jurek; Mai, Sabine; Cremer, Christoph (2018): Super-resolution binding activated localization microscopy through reversible change of DNA conformation. In: Nucleus 9, S. 182-189. Online verfügbar unter https://doi.org/10.1080/19491034.2017.1419846

     

    Abstract: Methods of super-resolving light microscopy (SRM) have found an exponentially growing range of applications in cell biology, including nuclear structure analyses. Recent developments have proven that Single Molecule Localization Microscopy (SMLM), a type of SRM, is particularly useful for enhanced spatial analysis of the cell nucleus due to its highest resolving capability combined with very specific fluorescent labeling. In this commentary we offer a brief review of the latest methodological development in the field of SMLM of chromatin designated DNA Structure Fluctuation Assisted Binding Activated Localization Microscopy (abbreviated as fBALM) as well as its potential future applications in biology and medicine.

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  • Brauchli, R.; Leutenegger, Tobias (2017): Licht für intelligente Maschinen. In: Unternehmerzeitung 23, S. 14-15

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  • Hauser-Ehninger, Ulrich (2017): Warum fliegt ein Flugzeug?. In: Wissensplatz, S. 12-13. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/september-2017/, zuletzt geprüft am 07.12.2018

     

    Abstract: Kann man eine Kerze hinter einer Flasche ausblasen? Und was hat das damit zu tun, dass das grösste Passagierflugzeug der Welt, mit einem Gewicht von bis zu 560 Tonnen, abheben und fliegen kann? Die neugierigen Teilnehmerinnen und Teilnehmer der «Uni für alle – Kids»-Veranstaltung wollen das herausfinden. Und wer weiss, vielleicht wird ja dabei eine zukünftige technische Fachkraft «geboren».

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  • Leutenegger, Tobias (2017): Die Photonik ist im Aufwind. Ausbildungsbedarf und -situation. In: bulletin.ch 108, S. 35-36. Online verfügbar unter https://www.bulletin.ch/de/news-detail/die-photonik-ist-im-aufwind.html, zuletzt geprüft am 21.02.2020

     

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  • Leutenegger, Tobias (2017): Licht hat Zukunft. In: Wissensplatz, S. 14-15. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/februar-2017/, zuletzt geprüft am 07.12.2018

     

    Abstract: Photonics ist eine der sechs key enabling technologies, welche die EU als zukunftsträchtigste Technologien definiert hat. Täglich sind wir mit Photonics konfrontiert. Die Wichtigkeit von Photonics nimmt auch in der Schweizer Wirtschaft stetig zu. Viele Schweizer Unternehmen sind mit ihren Photonics-Produkten weltweit führend. Das Wachstum der Branche führt zu einem steigenden Bedarf an Photonics-Ingenieurinnen und -Ingenieuren. Die HTW Chur bietet daher das schweizweit erste und einzigartige Bachelorstudium Photonics an.

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  • Leutenegger, Tobias (2017): Studium Photonics: Nahe an der Industrie. In: Photonik 49. Online verfügbar unter https://www.photonik.de/studium-photonics-nahe-an-der-industrie/150/25109/350467, zuletzt geprüft am 21.02.2020

     

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  • Birk, Udo; Szczurek, Aleksander; Cremer, Christoph (2017): Super-resolved linear fluorescence localization microscopy using photostable fluorophores. A virtual microscopy study. In: Optics Communications, S. 42-50. Online verfügbar unter https://doi.org/10.1016/j.optcom.2017.06.078, zuletzt geprüft am 06.05.2023

     

    Abstract: Current approaches to overcome the conventional limit of the resolution potential of light microscopy (of about 200 nm for visible light), often suffer from non-linear effects, which render the quantification of the image intensities in the reconstructions difficult, and also affect the quantification of the biological structure under investigation. As an attempt to face these difficulties, we discuss a particular method of localization microscopy which is based on photostable fluorescent dyes. The proposed method can potentially be implemented as a fast alternative for quantitative localization microscopy, circumventing the need for the acquisition of thousands of image frames and complex, highly dye-specific imaging buffers. Although the need for calibration remains in order to extract quantitative data (such as the number of emitters), multispectral approaches are largely facilitated due to the much less stringent requirements on imaging buffers. Furthermore, multispectral acquisitions can be readily obtained using commercial instrumentation such as e.g. the conventional confocal laser scanning microscope.

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  • Birk, Udo; Hase, Johann V.; Cremer, Christoph (2017): Super-resolution microscopy with very large working distance by means of distributed aperture illumination. In: Scientific reports 7. Online verfügbar unter https://doi.org/10.1038/s41598-017-03743-4, zuletzt geprüft am 06.05.2023

     

    Abstract: The limits of conventional light microscopy ("Abbe-Limit") depend critically on the numerical aperture (NA) of the objective lens. Imaging at large working distances or a large field-of-view typically requires low NA objectives, thereby reducing the optical resolution to the multi micrometer range. Based on numerical simulations of the intensity field distribution, we present an illumination concept for a super-resolution microscope which allows a three dimensional (3D) optical resolution around 150 nm for working distances up to the centimeter regime. In principle, the system allows great flexibility, because the illumination concept can be used to approximate the point-spread-function of conventional microscope optics, with the additional benefit of a customizable pupil function. Compared with the Abbe-limit using an objective lens with such a large working distance, a volume resolution enhancement potential in the order of 104 is estimated.

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  • Cremer, Christoph; Szczurek, Aleksander; Schock, Florian; Gourram, Amine; Birk, Udo (2017): Super-resolution microscopy approaches to nuclear nanostructure imaging. In: Methods, S. 11-32. Online verfügbar unter https://doi.org/10.1016/j.ymeth.2017.03.019, zuletzt geprüft am 06.05.2023

     

    Abstract: The human genome has been decoded, but we are still far from understanding the regulation of all gene activities. A largely unexplained role in these regulatory mechanisms is played by the spatial organization of the genome in the cell nucleus which has far-reaching functional consequences for gene regulation. Until recently, it appeared to be impossible to study this problem on the nanoscale by light microscopy. However, novel developments in optical imaging technology have radically surpassed the limited resolution of conventional far-field fluorescence microscopy (ca. 200nm). After a brief review of available super-resolution microscopy (SRM) methods, we focus on a specific SRM approach to study nuclear genome structure at the single cell/single molecule level, Spectral Precision Distance/Position Determination Microscopy (SPDM). SPDM, a variant of localization microscopy, makes use of conventional fluorescent proteins or single standard organic fluorophores in combination with standard (or only slightly modified) specimen preparation conditions; in its actual realization mode, the same laser frequency can be used for both photoswitching and fluorescence read out. Presently, the SPDM method allows us to image nuclear genome organization in individual cells down to few tens of nanometer (nm) of structural resolution, and to perform quantitative analyses of individual small chromatin domains; of the nanoscale distribution of histones, chromatin remodeling proteins, and transcription, splicing and repair related factors. As a biomedical research application, using dual-color SPDM, it became possible to monitor in mouse cardiomyocyte cells quantitatively the effects of ischemia conditions on the chromatin nanostructure (DNA). These novel "molecular optics" approaches open an avenue to study the nuclear landscape directly in individual cells down to the single molecule level and thus to test models of functional genome architecture at unprecedented resolution.

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  • Szczurek, Aleksander; Klewes, Ludger; Xing, Jun; Gourram, Amine; Birk, Udo; Knecht, Hans; Dobrucki, Jurek W.; Mai, Sabine; Cremer, Christoph (2017): Imaging chromatin nanostructure with binding-activated localization microscopy based on DNA structure fluctuations. In: Nucleic Acids Research 45. Online verfügbar unter https://doi.org/10.1093/nar/gkw1301, zuletzt geprüft am 06.05.2023

     

    Abstract: Advanced light microscopy is an important tool for nanostructure analysis of chromatin. In this report we present a general concept for Single Molecule localization Microscopy (SMLM) super-resolved imaging of DNA-binding dyes based on modifying the properties of DNA and the dye. By careful adjustment of the chemical environment leading to local, reversible DNA melting and hybridization control over the fluorescence signal of the DNA-binding dye molecules can be introduced. We postulate a transient binding as the basis for our variation of binding-activated localization microscopy (BALM). We demonstrate that several intercalating and minor-groove binding DNA dyes can be used to register (optically isolate) only a few DNA-binding dye signals at a time. To highlight this DNA structure fluctuation-assisted BALM (fBALM), we applied it to measure, for the first time, nanoscale differences in nuclear architecture in model ischemia with an anticipated structural resolution of approximately 50 nm. Our data suggest that this approach may open an avenue for the enhanced microscopic analysis of chromatin nano-architecture and hence the microscopic analysis of nuclear structure aberrations occurring in various pathological conditions. It may also become possible to analyse nuclear nanostructure differences in different cell types, stages of development or environmental stress conditions.

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  • Stettler, Niklaus; Wenk, Bruno (2016): Linked Data – zukunftsorientierte Organisation und Nutzung von Daten. In: Wissensplatz, S. 12-13. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/september-2016/, zuletzt geprüft am 13.12.2018

     

    Abstract: Daten sind das Fundament von Erkenntnissen: Daten zu Niederschlag und Luftdruck für Meteorologinnen, Börsendaten für Wirtschaftswissenschaftler. Daten sind aber auch die Basis für Entscheide: Fahrplandaten für Reisende, Fertigungsmessdaten für Qualitätsverantwortliche. In einem Forschungsprojekt wurde aufgezeigt, wie KMU mit «Linked Data» viele und heterogene Daten organisieren und nutzen können.

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  • Venzin, Toni (2016): «Innovation» aus den Effizienzlaboren. In: Wissensplatz, S. 10-11. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/februar-2016/, zuletzt geprüft am 24.01.2019

     

    Abstract: Die Dienstleistungslabore für Energieeffizienz und elektromagnetische Verträglichkeit (EMV) an der HTW Chur prüfen Konsumgeräte und Neuentwicklungen auf Einhaltung der geltenden Normen. Das Team unterstützt mit seinen Erfahrungen und Anregungen die Unternehmen bei der Verbesserung ihrer Produkte.

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  • Wenk, Bruno (2016): Digitale Geschäftsmodelle verlangen nach Spezialisten. In: PULS. Das Bündner Wirtschaftsmagazin

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  • Wenk, Bruno (2016): Interaktives Seminar auf Distanz – geht das?. In: Wissensplatz, S. 14-15. Online verfügbar unter https://www.fhgr.ch/fhgr/medien-und-oeffentlichkeit/publikationen/wissensplatz/februar-2016/, zuletzt geprüft am 24.01.2019

     

    Abstract: Um das Resultat gleich vorwegzunehmen : Ja, das geht. Die HTW Chur beweist, dass interaktive Seminare auf Distanz sogar eine Bereicherung für Studierende und Dozierende sein können. Der Versuch wurde im Bachelor-Studiengang Information Science vorgenommen. Wie kann ein Seminar, das im Wesentlichen von Präsentationen und Diskussionen von und mit allen Beteiligten lebt, mit örtlich verteilten Studierenden durchgeführt werden?

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  • Cremer, Christoph; Birk, Udo (2016): Perspectives in Super-Resolved Fluorescence Microscopy. What Comes Next?. In: Frontiers in Physics 4. Online verfügbar unter https://doi.org/10.3389/fphy.2016.00011, zuletzt geprüft am 06.05.2023

     

    Abstract: The Nobel Prize in Chemistry 2014 has been awarded to three scientists involved in the development of STED and PALM super-resolution fluorescence microscopy (SRM) methods. They have proven that it is possible to overcome the 100 year old theoretical limit for the resolution potential of light microscopy (of about 200 nm for visible light), which for decades has precluded a direct glimpse of the molecular machinery of life. None of the present-day super-resolution techniques have invalidated the Abbe limit for light optical detection; however, they have found clever ways around it. In this report, we discuss some of the challenges still to be resolved before arising SRM approaches will be fit to bring about the revolution in Biology and Medicine envisaged. Some of the challenges discussed are the applicability to image live and/or large samples, the further enhancement of resolution, future developments of labels, and multi-spectral approaches.

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  • Żurek-Biesiada, Dominika; Szczurek, Aleksander T.; Prakash, Kirti; Best, Gerrit; Mohana, Giriram K.; Lee, Hyun-Keun; Roignant, Jean-Yves; Dobrucki, Jurek W.; Cremer, Christoph; Birk, Udo (2016): Quantitative super-resolution localization microscopy of DNA in situ using Vybrant® DyeCycle™ Violet fluorescent probe. In: Data in Brief, S. 157-171. Online verfügbar unter https://doi.org/10.1016/j.dib.2016.01.041, zuletzt geprüft am 06.05.2023

     

    Abstract: Single Molecule Localization Microscopy (SMLM) is a recently emerged optical imaging method that was shown to achieve a resolution in the order of tens of nanometers in intact cells. Novel high resolution imaging methods might be crucial for understanding of how the chromatin, a complex of DNA and proteins, is arranged in the eukaryotic cell nucleus. Such an approach utilizing switching of a fluorescent, DNA-binding dye Vybrant® DyeCycle™ Violet has been previously demonstrated by us (Żurek-Biesiada et al., 2015) [1]. Here we provide quantitative information on the influence of the chemical environment on the behavior of the dye, discuss the variability in the DNA-associated signal density, and demonstrate direct proof of enhanced structural resolution. Furthermore, we compare different visualization approaches. Finally, we describe various opportunities of multicolor DNA/SMLM imaging in eukaryotic cell nuclei.

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  • Żurek-Biesiada, Dominika; Szczurek, Aleksander T.; Prakash, Kirti; Mohana, Giriram K.; Lee, Hyun-Keun; Roignant, Jean-Yves; Birk, Udo; Dobrucki, Jurek W.; Cremer, Christoph (2016): Localization microscopy of DNA in situ using Vybrant(®) DyeCycle™ Violet fluorescent probe. A new approach to study nuclear nanostructure at single molecule resolution. In: Experimental Cell Research 343, S. 97-106. Online verfügbar unter https://doi.org/10.1016/j.yexcr.2015.08.020, zuletzt geprüft am 06.05.2023

     

    Abstract: Higher order chromatin structure is not only required to compact and spatially arrange long chromatids within a nucleus, but have also important functional roles, including control of gene expression and DNA processing. However, studies of chromatin nanostructures cannot be performed using conventional widefield and confocal microscopy because of the limited optical resolution. Various methods of superresolution microscopy have been described to overcome this difficulty, like structured illumination and single molecule localization microscopy. We report here that the standard DNA dye Vybrant(®) DyeCycle™ Violet can be used to provide single molecule localization microscopy (SMLM) images of DNA in nuclei of fixed mammalian cells. This SMLM method enabled optical isolation and localization of large numbers of DNA-bound molecules, usually in excess of 10(6) signals in one cell nucleus. The technique yielded high-quality images of nuclear DNA density, revealing subdiffraction chromatin structures of the size in the order of 100nm; the interchromatin compartment was visualized at unprecedented optical resolution. The approach offers several advantages over previously described high resolution DNA imaging methods, including high specificity, an ability to record images using a single wavelength excitation, and a higher density of single molecule signals than reported in previous SMLM studies. The method is compatible with DNA/multicolor SMLM imaging which employs simple staining methods suited also for conventional optical microscopy.

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  • Szczurek, Aleksander; Xing, Jun; Birk, Udo; Cremer, Christoph (2016): Single Molecule Localization Microscopy of Mammalian Cell Nuclei on the Nanoscale. In: Frontiers in Genetics 7. Online verfügbar unter https://doi.org/10.3389/fgene.2016.00114, zuletzt geprüft am 06.05.2023

     

    Abstract: Nuclear texture analysis is a well-established method of cellular pathology. It is hampered, however, by the limits of conventional light microscopy (ca. 200 nm). These limits have been overcome by a variety of super-resolution approaches. An especially promising approach to chromatin texture analysis is single molecule localization microscopy (SMLM) as it provides the highest resolution using fluorescent based methods. At the present state of the art, using fixed whole cell samples and standard DNA dyes, a structural resolution of chromatin in the 50-100 nm range is obtained using SMLM. We highlight how the combination of localization microscopy with standard fluorophores opens the avenue to a plethora of studies including the spatial distribution of DNA and associated proteins in eukaryotic cell nuclei with the potential to elucidate the functional organization of chromatin. These views are based on our experience as well as on recently published research in this field.

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  • Neumann, Jan; Scherhag, Anne; Otten, Susanne; Shen, Fangxia; Leifke, Anna Lena; Birk, Udo; Greb, Christoph; Lucas, Kurt; Cremer, Christoph (2016): Chronic Inflammation Under the Microscope. In: Microscopy Today 24, S. 38-45. Online verfügbar unter https://doi.org/10.1017/S1551929516000894, zuletzt geprüft am 23.05.2023

     

    Abstract: In the course of chronic inflammation certain body areas are recurrently inflamed. This goes along with many human diseases. With the help of widefield light microscopy, the underlying processes can be examined from a cellular level to whole organisms. This article presents several widefield microscopy applications such as immunofluorescence, live-cell imaging, histology, and ratiometric analysis to get insight into the development of chronic inflammation, the related diseases, and their treatment.

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  • Vardanyan, Ekaterina; Mumenthaler, Rudolf; Wenk, Bruno; Schuldt, Karsten (2015): Unkonferenz als Bestandteil der Lehre und als Community-Treff. Infocamp 2014 mit dem Motto „Linked“, HTW Chur, 10./11. Oktober 2014. In: Bibliothek. Informatik. Technologie - b.i.t.online 18, S. 64-65. Online verfügbar unter https://www.b-i-t-online.de/heft/2015-01-index.php, zuletzt geprüft am 03.07.2020

     

    Abstract: Die Unkonferenz infocamphat sich als beliebtes Format zur Vernetzung und Weiterbildung etabliert und ist in die bibliothekarische Ausbildung der HTW Chur eingebunden. Die Workshops zeigten unter anderem, dass sich das Bild von Bibliothekar und Bibliothekarin in der Praxis zu wandeln scheint.

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  • Prakash, Kirti; Fournier, David; Redl, Stefan; Best, Gerrit; Borsos, Máté; Tiwari, Vijay K.; Tachibana-Konwalski, Kikuë; Ketting, René F.; Parekh, Sapun H.; Cremer, Christoph; Birk, Udo (2015): Superresolution imaging reveals structurally distinct periodic patterns of chromatin along pachytene chromosomes. In: Proceedings of the National Academy of Sciences of the United States of America 112, S. 14635-14640. Online verfügbar unter https://doi.org/10.1073/pnas.1516928112, zuletzt geprüft am 06.05.2023

     

    Abstract: During meiosis, homologous chromosomes associate to form the synaptonemal complex (SC), a structure essential for fertility. Information about the epigenetic features of chromatin within this structure at the level of superresolution microscopy is largely lacking. We combined single-molecule localization microscopy (SMLM) with quantitative analytical methods to describe the epigenetic landscape of meiotic chromosomes at the pachytene stage in mouse oocytes. DNA is found to be nonrandomly distributed along the length of the SC in condensed clusters. Periodic clusters of repressive chromatin [trimethylation of histone H3 at lysine (Lys) 27 (H3K27me3)] are found at 500-nm intervals along the SC, whereas one of the ends of the SC displays a large and dense cluster of centromeric histone mark [trimethylation of histone H3 at Lys 9 (H3K9me3)]. Chromatin associated with active transcription [trimethylation of histone H3 at Lys 4 (H3K4me3)] is arranged in a radial hair-like loop pattern emerging laterally from the SC. These loops seem to be punctuated with small clusters of H3K4me3 with an average spread larger than their periodicity. Our findings indicate that the nanoscale structure of the pachytene chromosomes is constrained by periodic patterns of chromatin marks, whose function in recombination and higher order genome organization is yet to be elucidated.

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  • Oleksiuk, Olga; Abba, Mohammed; Tezcan, Kerem Can; Schaufler, Wladimir; Bestvater, Felix; Patil, Nitin; Birk, Udo; Hafner, Mathias; Altevogt, Peter; Cremer, Christoph; Allgayer, Heike (2015): Single-Molecule Localization Microscopy allows for the analysis of cancer metastasis-specific miRNA distribution on the nanoscale. In: Oncotarget 6, S. 44745-44757. Online verfügbar unter https://doi.org/10.18632/oncotarget.6297, zuletzt geprüft am 06.05.2023

     

    Abstract: We describe a novel approach for the detection of small non-coding RNAs in single cells by Single-Molecule Localization Microscopy (SMLM). We used a modified SMLM-setup and applied this instrument in a first proof-of-principle concept to human cancer cell lines. Our method is able to visualize single microRNA (miR)-molecules in fixed cells with a localization accuracy of 10-15 nm, and is able to quantify and analyse clustering and localization in particular subcellular sites, including exosomes. We compared the metastasis-site derived (SW620) and primary site derived (SW480) human colorectal cancer (CRC) cell lines, and (as a proof of principle) evaluated the metastasis relevant miR-31 as a first example. We observed that the subcellular distribution of miR-31 molecules in both cell lines was very heterogeneous with the largest subpopulation of optically acquired weakly metastatic cells characterized by a low number of miR-31 molecules, as opposed to a significantly higher number in the majority of the highly metastatic cells. Furthermore, the highly metastatic cells had significantly more miR-31-molecules in the extracellular space, which were visualized to co-localize with exosomes in significantly higher numbers. From this study, we conclude that miRs are not only aberrantly expressed and regulated, but also differentially compartmentalized in cells with different metastatic potential. Taken together, this novel approach, by providing single molecule images of miRNAs in cellulo can be used as a powerful supplementary tool in the analysis of miRNA function and behaviour and has far reaching potential in defining metastasis-critical subpopulations within a given heterogeneous cancer cell population.

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  • Kirmes, Ina; Szczurek, Aleksander; Prakash, Kirti; Charapitsa, Iryna; Heiser, Christina; Musheev, Michael; Schock, Florian; Fornalczyk, Karolina; Ma, Dongyu; Birk, Udo; Cremer, Christoph; Reid, George (2015): A transient ischemic environment induces reversible compaction of chromatin. In: Genome Biology. Online verfügbar unter https://doi.org/10.1186/s13059-015-0802-2, zuletzt geprüft am 06.05.2023

     

    Abstract: BACKGROUND Cells detect and adapt to hypoxic and nutritional stress through immediate transcriptional, translational and metabolic responses. The environmental effects of ischemia on chromatin nanostructure were investigated using single molecule localization microscopy of DNA binding dyes and of acetylated histones, by the sensitivity of chromatin to digestion with DNAseI, and by fluorescence recovery after photobleaching (FRAP) of core and linker histones. RESULTS Short-term oxygen and nutrient deprivation of the cardiomyocyte cell line HL-1 induces a previously undescribed chromatin architecture, consisting of large, chromatin-sparse voids interspersed between DNA-dense hollow helicoid structures 40-700 nm in dimension. The chromatin compaction is reversible, and upon restitution of normoxia and nutrients, chromatin transiently adopts a more open structure than in untreated cells. The compacted state of chromatin reduces transcription, while the open chromatin structure induced upon recovery provokes a transitory increase in transcription. Digestion of chromatin with DNAseI confirms that oxygen and nutrient deprivation induces compaction of chromatin. Chromatin compaction is associated with depletion of ATP and redistribution of the polyamine pool into the nucleus. FRAP demonstrates that core histones are not displaced from compacted chromatin; however, the mobility of linker histone H1 is considerably reduced, to an extent that far exceeds the difference in histone H1 mobility between heterochromatin and euchromatin. CONCLUSIONS These studies exemplify the dynamic capacity of chromatin architecture to physically respond to environmental conditions, directly link cellular energy status to chromatin compaction and provide insight into the effect ischemia has on the nuclear architecture of cells.

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  • Öhrström, Lena; Fischer, Bernd M.; Bitzer, Andreas; Wallauer, Jan; Walther, Markus; Rühli, Frank (2015): Terahertz imaging modalities of ancient Egyptian mummified objects and of a naturally mummified rat. In: The anatomical record 298, S. 1135-1143. DOI: 10.1002/ar.23143

    Abstract: During the last few years, terahertz (THz) imaging has been used to investigate artwork and historic artifacts. The application of THz imaging to mummy investigations is very attractive since it provides spectroscopic information over a broad frequency range and its radiation has proven to be harmless to human cells. However, compared with the current standard imaging methods in mummy imaging-X-ray and computed tomography (CT)--it remains a novel, emerging technique whose potential still needs to be fully evaluated. Here, ancient Egyptian mummified objects as well as a naturally mummified rat have been investigated by two different THz imaging systems: a broadband THz time domain imaging system and an electronic THz scanner. The obtained THz images are compared with conventional CT, X-ray, and magnetic resonance images. While the broadband THz time domain setup permits analyses of smaller samples, the electronic THz scanner allows the recording of data of thicker and larger samples at the expense of a limited spectral bandwidth. Terahertz imaging shows clear potential for mummy investigations, although currently CT imaging offers much higher spatial resolution. Furthermore, as commercial mobile THz scanners become available, THz imaging could be applied directly in museums or at excavation sites.

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  • Reiss, Simon; Bitzer, Andreas; Bock, Michael (2015): An optical setup for electric field measurements in MRI with high spatial resolution. In: Physics in medicine and biology 60, S. 4355-4370. DOI: 10.1088/0031-9155/60/11/4355

    Abstract: Electric field measurements in the magnetic resonance (MR) imaging environment are important to assess potentially dangerous radio-frequency (RF) heating in the vicinity of metallic structures such as coils, implants or catheters. So far, E-field measurements have been performed with dipole antennas that lag of limited spatial resolution and which are difficult to use in the magnet bore as they interfere with the RF transmit field of the MRI system. In this work an electro-optic sensor is presented that utilizes the Pockels effect to measure the E-field in a clinical MR system with high spatial resolution. This sensor consists of dielectric materials only and thus, it only minimally influences the measured E-field distribution. A 10 m long flexible optical fiber connects the small sensor head to a remote processing unit where the optical signal is transformed into an electrical output signal. Spatially resolved qualitative E-field measurements were performed in a 1.5 T clinical MR system in the vicinity of metallic samples and an active tracking catheter with a resolution of up to 1 mm. The near-field pattern of a resonant U-shaped metallic sample was clearly identified and compared with numerical simulations. A more complex field behavior was found for the tracking catheter where strong E-field enhancements were observed at the distal tip and at its proximal part outside the phantom solution. Due to its sub-mm spatial resolution the optical sensor approach provides detailed insight into the complex and difficult to access field distributions close to implants and metallic structures and has turned out to be promising tool for MRI field and safety inspections.

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