ExoPlanet Optics: conceptual design processes for stealth telescopes

In this paper we examine several contrast-degrading static signature sources present in current terrestrial exoplanet Lyot Coronagraph/Telescope optical systems. These are: - Unnecessary optical surfaces, which increase cost, absorption, scatter, wavefront control and alignment issues. A suggested solution is to make every effort to investigate innovative solutions to reduce the number of optical surfaces during the early design phase. Consider free-form optics. - Diffraction from secondary support systems and classical hexagon segmented apertures, which masks the low IWA terrestrial exoplanets. A suggested mitigation is to investigate curved secondary support systems and a pinwheel architecture for the deployable primary aperture. - Polarization Fresnel and form birefringence aberrations, which distort the system PSF, introduce absorption, scatter and wavefront control issues. Mitigation is to reduce all ray-angles of incidence to a minimum, investigate zero-loss polarization compensation wavefront technology, and investigate metal thin film deposition processes required to minimize form birefringence in large-area high-reflectivity coatings. - Small-angle specular or resolved angle scattered light, which places a narrow halo of incoherent light around the base of the PSF. There is no requirement on mirror smooth-surface scatter. Investigate the physical source of the small angle scatter and develop mirror polishing and thin film deposition processes to minimize scatter

Multi-objective optimisation for receiver operating characteristic analysis

Copyright © 2006 Springer-Verlag Berlin Heidelberg. The final publication is available at link.springer.comBook title: Multi-Objective Machine LearningSummary Receiver operating characteristic (ROC) analysis is now a standard tool for the comparison of binary classifiers and the selection operating parameters when the costs of misclassification are unknown. This chapter outlines the use of evolutionary multi-objective optimisation techniques for ROC analysis, in both its traditional binary classification setting, and in the novel multi-class ROC situation. Methods for comparing classifier performance in the multi-class case, based on an analogue of the Gini coefficient, are described, which leads to a natural method of selecting the classifier operating point. Illustrations are given concerning synthetic data and an application to Short Term Conflict Alert

GLS-1, a Novel P Granule Component, Modulates a Network of Conserved RNA Regulators to Influence Germ Cell Fate Decisions

Post-transcriptional regulatory mechanisms are widely used to influence cell fate decisions in germ cells, early embryos, and neurons. Many conserved cytoplasmic RNA regulatory proteins associate with each other and assemble on target mRNAs, forming ribonucleoprotein (RNP) complexes, to control the mRNAs translational output. How these RNA regulatory networks are orchestrated during development to regulate cell fate decisions remains elusive. We addressed this problem by focusing on Caenorhabditis elegans germline development, an exemplar of post-transcriptional control mechanisms. Here, we report the discovery of GLS-1, a new factor required for many aspects of germline development, including the oocyte cell fate in hermaphrodites and germline survival. We find that GLS-1 is a cytoplasmic protein that localizes in germ cells dynamically to germplasm (P) granules. Furthermore, its functions depend on its ability to form a protein complex with the RNA-binding Bicaudal-C ortholog GLD-3, a translational activator and P granule component important for similar germ cell fate decisions. Based on genetic epistasis experiments and in vitro competition experiments, we suggest that GLS-1 releases FBF/Pumilio from GLD-3 repression. This facilitates the sperm-to-oocyte switch, as liberated FBF represses the translation of mRNAs encoding spermatogenesis-promoting factors. Our proposed molecular mechanism is based on the GLS-1 protein acting as a molecular mimic of FBF/Pumilio. Furthermore, we suggest that a maternal GLS-1/GLD-3 complex in early embryos promotes the expression of mRNAs encoding germline survival factors. Our work identifies GLS-1 as a fundamental regulator of germline development. GLS-1 directs germ cell fate decisions by modulating the availability and activity of a single translational network component, GLD-3. Hence, the elucidation of the mechanisms underlying GLS-1 functions provides a new example of how conserved machinery can be developmentally manipulated to influence cell fate decisions and tissue development

The endothelial glycocalyx: composition, functions, and visualization

This review aims at presenting state-of-the-art knowledge on the composition and functions of the endothelial glycocalyx. The endothelial glycocalyx is a network of membrane-bound proteoglycans and glycoproteins, covering the endothelium luminally. Both endothelium- and plasma-derived soluble molecules integrate into this mesh. Over the past decade, insight has been gained into the role of the glycocalyx in vascular physiology and pathology, including mechanotransduction, hemostasis, signaling, and blood cell–vessel wall interactions. The contribution of the glycocalyx to diabetes, ischemia/reperfusion, and atherosclerosis is also reviewed. Experimental data from the micro- and macrocirculation alludes at a vasculoprotective role for the glycocalyx. Assessing this possible role of the endothelial glycocalyx requires reliable visualization of this delicate layer, which is a great challenge. An overview is given of the various ways in which the endothelial glycocalyx has been visualized up to now, including first data from two-photon microscopic imaging

Mueller Polarimetry for Quantifying the Stress Optic Coefficient in the Infrared

The stress optic coefficient of an infrared transmitting material was measured at room temperature at a wavelength of 1550nm. This work discusses a Mueller matrix imaging experiment to measure the stress optic coefficient, observe the spatial distribution of birefringence, and quantify experimental sources of uncertainty. A one-inch diameter disk of sample material was diametrically loaded with increasing force, and linear retardance was measured in the central region. Finite element and analytical modeling was done to estimate the magnitude of stress in this central region. A Rotating Retarder Mueller Matrix Imaging Polarimeter measured the spatial distribution of linear retardance. The retardance is related to the change in birefringence with stress magnitude. The slope of this linear fit is the stress optic coefficient. The stress optic coefficient of the infrared transmitting material was measured to be 1.89 ± 0.1424 [TPa]−1. To test the precision of our stress optic coefficient measurement procedure, a 1-inch diameter N-BK7 disk was measured at a wavelength of 1550nm and compared with industry-accepted values. The stress optic coefficient of N-BK7 was measured as 2.83 ± 0.1057[TPa]−1. The published N-BK7 value measured at visible wavelengths is 2.77 [TPa]−1 ± 3%.1-3 This agreement validates the experimental Mueller matrix imaging methods and supports the common assumption of minor wavelength dependence of the stress optic coefficient. © 2023 SPIE.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

UV linear stokes imaging of optically thin clouds

Cirrus clouds are important to the radiation energy budget due to their temporal duration and >50% global coverage.1 The variety of ice crystal shapes and sizes in a cirrus cloud create challenges differentiating radiation insulated by the Earth's atmosphere from that reflected back to space. The optical thickness of these clouds is often too thin to be sensed using any current passive satellite radiometers. Sensitivity studies in the UV have shown that the angle of linear polarization (AoLP) of solar radiation backscattered from thin cirrus clouds and thin liquid water clouds is rotated.2 Pust and Shaw also demonstrated subvisual clouds detection in degree of linear polarization (DoLP) and AoLP.3 An Ultraviolet Stokes Imaging Polarimeter (ULTRASIP) was designed and developed for optically thin clouds and sky observations in the 360 nm - 450 nm range.4 ULTRASIP is a time modulated polarimeter rotating a wire-grid polarizer in front of a 16-bit, water-cooled, back-illuminated CCD sensor. Polarized light scattering models will be compared in the visible and the UV to motivate measurements in this waveband.5. © 2021 SPIE.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]