636 research outputs found
The Military-News Media Relationship: Thinking Forward
Over the course of the next six months, the Strategic Studies Institute will examine the impact of the media\u27s technological advances on strategic and operational level planning and policymaking, first in an overseas theater, and subsequently on decisions made at the national level. The first of these two studies recognizes the complexity of executing military operations under the scrutiny of a very responsive, high technology world news media. Given the volatile, unstable, and ambiguous environment in which armed forces can find themselves, the actions of field forces have a greater chance than ever before of affecting subsequent strategic decisions made at higher levels. The pressure on field commanders to get it right the first time is demonstrably greater than ever. The author intends that these thoughts provide commanders with an understanding of the high technology and competitive news media environment they can expect to experience and offers specific suggestions for successfully communicating with reporters.https://press.armywarcollege.edu/monographs/1901/thumbnail.jp
Can community volunteers work to trace patients defaulting from scheduled psychiatric clinic appointments?
Reproduced with permission of the publisher
Development of a Design Tool for Flow Rate Optimization in the Tata Swach Water Filter
When developing a first-generation product, an iterative approach often yields the shortest time-to-market. In order to optimize its performance, however, a fundamental understanding of the theory governing its operation becomes necessary. This paper details the optimization of the Tata Swach, a consumer water purifier produced for India. The primary objective of the work was to increase flow rate while considering other factors such as cost, manufacturability, and efficacy. A mathematical model of the flow characteristics through the filter was developed. Based on this model, a design tool was created to allow designers to predict flow behavior without prototyping, significantly reducing the necessity of iteration. Sensitivity analysis was used to identify simple ways to increase flow rate as well as potential weak points in the design. Finally, it was demonstrated that maximum flow rate can be increased by 50% by increasing the diameter of a flow-restricting feature while simultaneously increasing the length of the active purification zone. This can be accomplished without significantly affecting cost, manufacturability, and efficacy.MIT Tata Center for Technology and Desig
Electron attachment rates for PAH anions in the ISM and dark molecular clouds: dependence on their chemical properties
CONTEXT: The attachment of free electrons to polycondensed aromatic ring
molecules (PAHs) is studied for the variety of these molecules with different
numbers of condensed rings and over a broad range of electron temperatures,
using a multichannel quantum scattering approach. The calculations of the
relevant cross sections are used in turn to model the corresponding attachment
rates for each of the systems under study, and these rates are parametrized as
a function of temperature using a commonly employed expression for two-body
processes in the interstellar medium (ISM). AIM: The scope of this work is to
use first principles to establish the influence of chemical properties on the
efficiency of the electron-attachment process for PAHs. METHODS: Quantum
multichannel scattering methods are employed to generate the relevant cross
sections, hence the attachment rates, using integral elastic cross sections
computed over a broad range of relevant energies, from threshold up to 1000 K
and linking the attachment to low-energy resonant collisions. RESULTS: The
rates obtained for the present molecules are found to markedly vary within the
test ensemble of the present work and to be lower than the earlier values used
for the entire class of PAHs anions, when modelling their evolutions in ISM
environments. The effects of such differences on the evolutions of chemical
networks that include both PAH and PAH- species are analysed in some detail and
related to previous calculations.Comment: accepted to be published on A&
Integration of CUF Micromechanics Framework into NASMAT for Multiscale Analysis of Fiber-Reinforced Composites
Uniaxial Tensile Properties of AS4 3D Woven Composites with Four Different Resin Systems: Experimental Results and Analysis: Property Computations
As a part of the NASA Composite Technology for Exploration project, eight different AS4 3D orthogonal woven composite panels were manufactured and were subjected to mechanical testing including uniaxial tension along the weaves' warp direction. Each set, with four different resin systems (KCR-IR6070, EP2400, RTM6, and RS-50), included weave architectures designed using 12K and 6K AS4 carbon fiber yarns. For the tension testing conducted at Room Temperature Ambient (RTA) conditions, the elastic modulus and strength of these eight panels (as-processed and thermally-cycled) were measured and compared while the potential evolution of micro-cracking before and after thermal cycling were monitored via optical microscopy and X-Ray Computed Tomography. The data set also included test results of the as-processed materials at Elevated Temperature Wet (ETW) conditions. In the second part of this study, efforts were made to compute elastic constants for AS4 6K/RTM6 and AS4 12K/RTM6 materials by implementing a finite element approach and the Multiscale Generalized Method of Cells (MSGMC) technique developed at NASA Glenn Research Center. Digimat-FE was used to model the weave architectures, assign properties, calculate yarn properties, create the finite element mesh, and compute the elastic properties by applying periodic boundary conditions to finite element models of each repeating unit cell. The required input data for MSGMC was generated using Matlab from Digimat exported weave information. Experimental and computational results were compared, and the differences and limitations in correlating to the test data were briefly discussed
Impaired Competence for Pretense in Children with Autism: Exploring Potential Cognitive Predictors.
Lack of pretense in children with autism has been explained by a number of theoretical explanations, including impaired mentalising, impaired response inhibition, and weak central coherence. This study aimed to empirically test each of these theories. Children with autism (n=60) were significantly impaired relative to controls (n=65) when interpreting pretense, thereby supporting a competence deficit hypothesis. They also showed impaired mentalising and response inhibition, but superior local processing indicating weak central coherence. Regression analyses revealed that mentalising significantly and independently predicted pretense. The results are interpreted as supporting the impaired mentalising theory and evidence against competing theories invoking impaired response inhibition or a local processing bias. The results of this study have important implications for treatment and intervention
Evidence for Quantum Interference in SAMs of Arylethynylene Thiolates in Tunneling Junctions with Eutectic Ga-In (EGaIn) Top-Contacts
This paper compares the current density (J) versus applied bias (V) of self-assembled monolayers (SAMs) of three different ethynylthiophenol-functionalized anthracene derivatives of approximately the same thickness with linear-conjugation (AC), cross-conjugation (AQ), and broken-conjugation (AH) using liquid eutectic Ga-In (EGaIn) supporting a native skin (~1 nm thick) of Ga2O3 as a nondamaging, conformal top-contact. This skin imparts non-Newtonian rheological properties that distinguish EGaIn from other top-contacts; however, it may also have limited the maximum values of J observed for AC. The measured values of J for AH and AQ are not significantly different (J â 10-1 A/cm2 at V = 0.4 V). For AC, however, J is 1 (using log averages) or 2 (using Gaussian fits) orders of magnitude higher than for AH and AQ. These values are in good qualitative agreement with gDFTB calculations on single AC, AQ, and AH molecules chemisorbed between Au contacts that predict currents, I, that are 2 orders of magnitude higher for AC than for AH at 0 < |V| < 0.4 V. The calculations predict a higher value of I for AQ than for AH; however, the magnitude is highly dependent on the position of the Fermi energy, which cannot be calculated precisely. In this sense, the theoretical predictions and experimental conclusions agree that linearly conjugated AC is significantly more conductive than either cross-conjugated AQ or broken conjugate AH and that AQ and AH cannot necessarily be easily differentiated from each other. These observations are ascribed to quantum interference effects. The agreement between the theoretical predictions on single molecules and the measurements on SAMs suggest that molecule-molecule interactions do not play a significant role in the transport properties of AC, AQ, and AH.
Kinetic Scaffolding Mediated by a Phospholipase C-Â and Gq Signaling Complex
Transmembrane signals initiated by a broad range of extracellular stimuli converge on nodes that regulate phospholipase C (PLC)âdependent inositol lipid hydrolysis for signal propagation. We describe how heterotrimeric guanine nucleotideâbinding proteins (G proteins) activate PLC-ÎČs and in turn are deactivated by these downstream effectors. The 2.7-angstrom structure of PLC-ÎČ3 bound to activated Gαq reveals a conserved module found within PLC-ÎČs and other effectors optimized for rapid engagement of activated G proteins. The active site of PLC-ÎČ3 in the complex is occluded by an intramolecular plug that is likely removed upon G proteinâdependent anchoring and orientation of the lipase at membrane surfaces. A second domain of PLC-ÎČ3 subsequently accelerates guanosine triphosphate hydrolysis by Gαq, causing the complex to dissociate and terminate signal propagation. Mutations within this domain dramatically delay signal termination in vitro and in vivo. Consequently, this work suggests a dynamic catch-and-release mechanism used to sharpen spatiotemporal signals mediated by diverse sensory inputs
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