Application of Near-Infrared Reflectance Spectroscopy to Estimate Post Mortem Interval

Estimating the post mortem interval of human remains is extremely important in death scene investigations. Currently, the rate of decomposition is gaged by a number of techniques, such as insect development, a function in part of environmental and weather conclusions. However, there are limitations with the process that prevent more accurate assessments. Near-infrared reflectance spectroscopy may provide complimentary and supportive estimates of the post mortem interval. The goal of this research was to determine if near-infrared reflectance spectroscopy (NIRS) could detect changes in decomposing skin of feral swine as a model system. NIRS spectra were obtained from swine skin samples exposed to natural elements (daily temperature, precipitation, humidity and solar radiation) on the campus of Texas A&M University during warm (July) and cool (February) seasons. Linear regression analysis of spectral data by sample age and state of decomposition were found to be highly correlated (R2=0.8749) during the warm period exposure. The same regression analysis of spectral data taken during the cool exposure months produced an R2 of 0.812

Theoretical investigations of the role of excluded volume, topological constraints, and attractive forces in the slow dynamics of soft matter systems

Soft matter physics has been continuously growing over the last 50 years due to its implications in physics, biology, chemistry, and materials science. One interest in the field arises from the viscoelastic nature of such materials; depending on the length and time scales studied the material can be more akin to a liquid (viscous) or a solid (elastic). Viscoelasticity is a seemingly generic phenomena, observed in many systems such as atomic, molecular, colloidal, and polymeric liquids, glasses and gels. Broadly there are three common microscopic mechanisms that describe such behavior: (i) excluded volume constraints and caging, (ii) topological or connectivity constraints, and (iii) attractive forces and physical bonding. The goal of this thesis is to develop microscopic force based theories to understand the slow dynamics of various soft matter systems. The starting point for all such theories is the generalized Langevin equation, which is characterized by the force-force time correlation function. By developing a self-consistent theory for the force correlations in terms of the packing structure of the fluid we are able to predict a dramatic slowing down of collective dynamics and the possible transition to activated "hopping" motions. With these guiding principles, we studied the role of excluded volume, topology and attractions in atomic, molecular, colloidal, and polymeric liquids. This thesis can be roughly divided into two parts: (i) studies of excluded volume and attractive forces in spherical particle liquids, and (ii) the role of connectivity and topological constraints in polymeric liquids. The former studies are primarily discussed in Chapters 3 and 4, where we answer questions about the interplay of repulsive and attractive forces in the single and two particle slow dynamics. The latter studies are discussed in Chapters 5 - 8, which discuss the emergence of and consequences of entanglements in dense polymer liquids, melts, and nanocomposites. In all cases repeated comparisons with recent simulations and experiments are in good agreement with the theoretical predictions. These results pave the way for future statistical mechanical developments

Correlated two-particle diffusion in dense colloidal suspensions at early times: Theory and comparison to experiment

The spatially resolved diffusive dynamic cross correlations of a pair of colloids in dense quasi-two-dimensional monolayers of identical particles are studied experimentally and theoretically at early times where motion is Fickian. In very dense systems where strong oscillatory equilibrium packing correlations are present, we find an exponential decay of the dynamic cross correlations on small and intermediate length scales. At large separations where structure becomes random, an apparent power law decay with an exponent of approximately -2.2 is observed. For a moderately dense suspension where local structural correlations are essentially absent, this same apparent power law decay is observed over all probed interparticle separations. A microscopic nonhydrodynamic theory is constructed for the dynamic cross correlations which is based on interparticle frictional effects and effective structural forces. Hydrodynamics enters only via setting the very short-time single-particle self-diffusion constant. No-adjustable-parameter quantitative predictions of the theory for the dynamic cross correlations are in good agreement with experiment over all length scales. The origin of the long-range apparent power law is the influence of the constraint of fixed interparticle separation on the amplitude of the mean square force exerted on the two tagged particles by the surrounding fluid. The theory is extended to study high-packing-fraction 3D hard sphere fluids. The same pattern of an oscillatory exponential form of the dynamic cross correlation function is predicted in the structural regime, but the long-range tail decays faster than in monolayers with an exponent of -3open

Casier: Structures for Composing Tangibles and Complementary Interactors for Use Across Diverse Systems

International audienceCasiers are a class of tangible interface elements that structure the physical and functional composition of tangibles and complementary interactors (e.g., buttons and sliders). Casiers allow certain subsets of interactive functionality to be accessible across diverse interactive systems (with and without graphical mediation, employing varied sensing capabilities and supporting software). We illustrate examples of casiers in use, including iterations around a custom walk-up-and-use kiosk, as well as casiers operable across com- mercial platforms of widely varying cost and capability

Carbon-sensitive pedotransfer functions for plant available water

Currently accepted pedotransfer functions show negligible effect of management-induced changes to soil organic carbon (SOC) on plant available water holding capacity (θAWHC), while some studies show the ability to substantially increase θAWHC through management. The Soil Health Institute\u27s North America Project to Evaluate Soil Health Measurements measured water content at field capacity using intact soil cores across 124 long-term research sites that contained increases in SOC as a result of management treatments such as reduced tillage and cover cropping. Pedotransfer functions were created for volumetric water content at field capacity (θFC) and permanent wilting point (θPWP). New pedotransfer functions had predictions of θAWHC that were similarly accurate compared with Saxton and Rawls when tested on samples from the National Soil Characterization database. Further, the new pedotransfer functions showed substantial effects of soil calcareousness and SOC on θAWHC. For an increase in SOC of 10 g kg–1 (1%) in noncalcareous soils, an average increase in θAWHC of 3.0 mm 100 mm–1 soil (0.03 m3 m–3) on average across all soil texture classes was found. This SOC related increase in θAWHC is about double previous estimates. Calcareous soils had an increase in θAWHC of 1.2 mm 100 mm–1 soil associated with a 10 g kg–1 increase in SOC, across all soil texture classes. New equations can aid in quantifying benefits of soil management practices that increase SOC and can be used to model the effect of changes in management on drought resilience

Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage

Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are typically greater in agricultural soils managed with minimal physical disturbance, the mechanisms driving the increases remain poorly understood. This study assessed bacterial and archaeal community structure and potential microbial drivers of Cmin in soils maintained under various degrees of physical disturbance. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results showed that type of cropping system, intensity of physical disturbance, and soil pH influenced microbial sensitivity to physical disturbance. Furthermore, 28% of amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as enriched under minimal disturbance and important for modeling Cmin, were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for tolerating environmental stressors. Understanding how physical disturbance shapes microbial communities across climates and inherent soil properties and drives changes in Cmin provides the context necessary to evaluate management impacts on standardized measures of soil microbial activity

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure