Browsing by Subject "Lighting"
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Item Open Access Instrument independent diffuse reflectance spectroscopy.(J Biomed Opt, 2011-01) Yu, Bing; Fu, Henry L; Ramanujam, NirmalaDiffuse reflectance spectroscopy with a fiber optic probe is a powerful tool for quantitative tissue characterization and disease diagnosis. Significant systematic errors can arise in the measured reflectance spectra and thus in the derived tissue physiological and morphological parameters due to real-time instrument fluctuations. We demonstrate a novel fiber optic probe with real-time, self-calibration capability that can be used for UV-visible diffuse reflectance spectroscopy in biological tissue in clinical settings. The probe is tested in a number of synthetic liquid phantoms over a wide range of tissue optical properties for significant variations in source intensity fluctuations caused by instrument warm up and day-to-day drift. While the accuracy for extraction of absorber concentrations is comparable to that achieved with the traditional calibration (with a reflectance standard), the accuracy for extraction of reduced scattering coefficients is significantly improved with the self-calibration probe compared to traditional calibration. This technology could be used to achieve instrument-independent diffuse reflectance spectroscopy in vivo and obviate the need for instrument warm up and post∕premeasurement calibration, thus saving up to an hour of precious clinical time.Item Open Access Long-duration animal tracking in difficult lighting conditions.(Sci Rep, 2015-07-01) Stern, Ulrich; Zhu, Edward Y; He, Ruo; Yang, Chung-HuiHigh-throughput analysis of animal behavior requires software to analyze videos. Such software typically depends on the experiments' being performed in good lighting conditions, but this ideal is difficult or impossible to achieve for certain classes of experiments. Here, we describe techniques that allow long-duration positional tracking in difficult lighting conditions with strong shadows or recurring "on"/"off" changes in lighting. The latter condition will likely become increasingly common, e.g., for Drosophila due to the advent of red-shifted channel rhodopsins. The techniques enabled tracking with good accuracy in three types of experiments with difficult lighting conditions in our lab. Our technique handling shadows relies on single-animal tracking and on shadows' and flies' being accurately distinguishable by distance to the center of the arena (or a similar geometric rule); the other techniques should be broadly applicable. We implemented the techniques as extensions of the widely-used tracking software Ctrax; however, they are relatively simple, not specific to Drosophila, and could be added to other trackers as well.Item Open Access Optimization of a widefield structured illumination microscope for non-destructive assessment and quantification of nuclear features in tumor margins of a primary mouse model of sarcoma.(PloS one, 2013-01) Fu, Henry L; Mueller, Jenna L; Javid, Melodi P; Mito, Jeffrey K; Kirsch, David G; Ramanujam, Nimmi; Brown, J QuincyCancer is associated with specific cellular morphological changes, such as increased nuclear size and crowding from rapidly proliferating cells. In situ tissue imaging using fluorescent stains may be useful for intraoperative detection of residual cancer in surgical tumor margins. We developed a widefield fluorescence structured illumination microscope (SIM) system with a single-shot FOV of 2.1 × 1.6 mm (3.4 mm(2)) and sub-cellular resolution (4.4 µm). The objectives of this work were to measure the relationship between illumination pattern frequency and optical sectioning strength and signal-to-noise ratio in turbid (i.e. thick) samples for selection of the optimum frequency, and to determine feasibility for detecting residual cancer on tumor resection margins, using a genetically engineered primary mouse model of sarcoma. The SIM system was tested in tissue mimicking solid phantoms with various scattering levels to determine impact of both turbidity and illumination frequency on two SIM metrics, optical section thickness and modulation depth. To demonstrate preclinical feasibility, ex vivo 50 µm frozen sections and fresh intact thick tissue samples excised from a primary mouse model of sarcoma were stained with acridine orange, which stains cell nuclei, skeletal muscle, and collagenous stroma. The cell nuclei were segmented using a high-pass filter algorithm, which allowed quantification of nuclear density. The results showed that the optimal illumination frequency was 31.7 µm(-1) used in conjunction with a 4 × 0.1 NA objective (v=0.165). This yielded an optical section thickness of 128 µm and an 8.9 × contrast enhancement over uniform illumination. We successfully demonstrated the ability to resolve cell nuclei in situ achieved via SIM, which allowed segmentation of nuclei from heterogeneous tissues in the presence of considerable background fluorescence. Specifically, we demonstrate that optical sectioning of fresh intact thick tissues performed equivalently in regards to nuclear density quantification, to physical frozen sectioning and standard microscopy.Item Open Access The Blue Devils and Energy Reduction: The Krzyzewski Center for Athletic Excellence and Cameron Indoor Stadium(2013-04-23) Rytel, TenaThere is a growing role for sports in the sustainability movement. With the ability to unite people and deliver environmental messages without political motive, sports can play a key role in helping teams and universities to make great strides in reducing their energy use and carbon dioxide emissions. Duke University has set a goal to be carbon neutral by 2024. To help reach this goal I conducted an energy audit of the Krzyzewski Center and a lighting retrofit feasibility study for the courts in the Krzyzewski Center and Cameron Indoor Stadium. This led to recommendations to Duke’s Facility Management Department and the Duke Athletics Department on how to lower energy use. I recommend that Duke Athletics consider using LEDs in the Krzyzewski Center and Cameron Indoor, as they provide considerable energy and maintenance savings, with more appealing payback estimates than alternative lighting options. Duke has the opportunity to pioneer the use of LED lights in indoor performance spaces, making Cameron Indoor as one of the first indoor courts, both in collegiately and professionally, to use LEDs. Additionally, I recommend that Duke Facilities apply window solar films and implement other lighting changes that will improve occupancy comfort in the Krzyzewski Center.Item Open Access The dynamics of successive induction in larval zebrafish.(J Exp Anal Behav, 2010-09) Staddon, JER; MacPhail, RC; Padilla, SCharles Sherrington identified the properties of the synapse by purely behavioral means-the study of reflexes-more than 100 years ago. They were subsequently confirmed neurophysiologically. Studying reflex interaction, he also showed that activating one reflex often facilitates another, antagonistic one: successive induction, which has since been demonstrated in a wide range of species, from aphids to locusts to dogs and humans. We show a particularly orderly example in zebrafish (Danio rerio) larvae; the behavior (locomotion) of larvae is low in dark and intermediate in light, but low in light and substantially higher in dark when dark followed light. A quantitative model of a simple dynamic process is described that readily captures the behavior pattern and the effects of a number of manipulations of lighting conditions.