Browsing by Subject "detectors"
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Item Cell deformation cytometry using diode-bar optical stretchers(Society of Photo-Optical Instrumentation Engineers., 2010-08-04) Sraj, Ihab; Eggleton, Charles D.; Jimenez, Ralph; Hoover, Erich E.; Squier, Jeffrey A.; Chichester, Justin; Marr, David W.The measurement of cell elastic parameters using optical forces has great potential as a reagent-free method for cell classification, identification of phenotype, and detection of disease; however, the low throughput associated with the sequential isolation and probing of individual cells has significantly limited its utility and application. We demonstrate a single-beam, high-throughput method where optical forces are applied anisotropically to stretch swollen erythrocytes in microfluidic flow. We also present numerical simulations of model spherical elastic cells subjected to optical forces and show that dual, opposing optical traps are not required and that even a single linear trap can induce cell stretching, greatly simplifying experimental implementation. Last, we demonstrate how the elastic modulus of the cell can be determined from experimental measurements of the equilibrium deformation. This new optical approach has the potential to be readily integrated with other cytometric technologies and, with the capability of measuring cell populations, enabling true mechanical-property-based cell cytometry.Item Effect of additives: organic-metal oxide nanocomposites for γ-ray sensors(SPIE, 2018-05-23) Singh, N. B.; Su, Ching Hua; Arnold, Bradley; Choa, Fow-Sen; Cooper, Christopher; Sova, Stacey; Gill, Puneet; Dayal, Vishall; Kelly, Lisa; Prasad, Narasimha; Smith, Paul; Cullum, BrianThe transition metal oxide embodied organic composites have great promise for high energy radiation detection. The interaction of high energy radiation such as γ-rays with the organic composite can generate photoelectric responses, Compton scattering and electron hole pairs, which can provide favorable properties to enhance the radiation detectivity of the composite. These effects along with changes of oxidation state of metal oxides, provide significant change in the electrical characteristics of composites due to radiation exposure. We have developed nickel oxide (NiO₂) nanoparticles embodied urea composite (urea-NiO₂), and determined effect of γ-radiation on the current – voltage characteristics in the frequency range of 100 Hz to 100,000Hz. In this paper, we describe the results of effect of additional oxidizing agent MnO₂ (urea-NiO₂-MnO₂) on the morphology, processing and current voltage characteristics due to exposure of Cs-137 γ-radiation. It was observed that addition of MnO₂ in urea-NiO₂ composite decreases the sensitivity of detection. However, urea-NiO₂-MnO₂ composite recovers to original properties after irradiation much faster than urea-NiO₂ composite.Item Effect of additives: γ-Ray sensors based on ionizing organic nanocompositesDayal, Vishall; Cooper, Christopher; Sova, Stacey; Gill, Puneet; Su, Ching-Hua; Arnold, Bradley; Choa, Fow-Sen; Kelly, Lisa; Cullum, Brian; Smith, Paul; Singh, N. B.We have developed ionizing organic based composites which have demonstrated great promise for radiation sensing. Nickel oxide has been proven as an active material for detecting high energy radiation. The oxidation state of unusual oxides such as nickel oxide in nanocomposites of ionizing organics changes much faster than thin film or bulk, and hence increases the sensitivity for radiation sensing. The resistivity of the oxide composite increases following sequential irradiation processes because of the decrease in holes' concentration. In this paper, we will present the effect of additional oxidizing agent on the morphology, processing and sensing of γ-ray by oxides - urea based nanocomposites. It was observed that addition of MnO₂ decreases the sensitivity. However, it recovers to original properties after irradiation much faster than undoped composites.Item Principal component analysis of up-the-ramp sampled infrared array data(SPIE, 2019-04-09) Rauscher, Bernard J.; Arendt, Richard; Fixsen, Dale J.; Kutyrev, Alexander; Mosby, Gregory; Moseley, Samuel H.We describe the results of principal component analysis (PCA) of up-the-ramp sampled infrared (IR) array data from the Hubble Space Telescope wide field camera 3 (WFC3 IR), James Webb Space Telescope NIRSpec, and prototype Wide Field Infrared Survey Telescope’s wide field instrument detectors. These systems use, respectively, Teledyne H1R, H2RG, and H4RG-10 near-IR detector arrays with a variety of IR array controllers. The PCA shows that the Legendre polynomials approximate the principal components of these systems (i.e., they roughly diagonalize the covariance matrix). In contrast to the monomial basis that is widely used for polynomial fitting and linearization today, the Legendre polynomials are an orthonormal basis. They provide a quantifiable, compact, and (nearly) linearly uncorrelated representation of the information content of the data. By fitting a few Legendre polynomials, nearly all of the meaningful information in representative WFC3 astronomical datacubes can be condensed from 15 up-the-ramp samples down to 6 compressible Legendre coefficients per pixel. The higher order coefficients contain time domain information that is lost when one projects up-the-ramp sampled datacubes onto two-dimensional images by fitting a straight line, even if the data are linearized before fitting the line. Going forward, we believe that this time domain information is potentially important for disentangling the various nonlinearities that can affect IR array observations, i.e., inherent pixel nonlinearity, persistence, burn in, brighter-fatter effect, (potentially) nonlinear interpixel capacitance, and perhaps others.