22,319 research outputs found

    A Social Controversy: Autism Spectrum Disorder\u27s Correlation to the Measles-Mumps-Rubella Vaccination

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    A 1998 research study lead by Dr. Andrew Wakefield linked the measles-mumps-rubella (MMR) vaccination as a probable cause to autism spectrum disorder. This publication has started a significant debate among healthcare professionals and instigated an anti-vaccination movement within the general population. This vaccination controversy was started by parents who readily accepted Wakefield’s findings as truth and frequently would choose to withdrawal the administration of vaccinations from their children’s care plans. There has also been disapproval by healthcare professionals over Wakefield’s study since numerous research teams have been unable to replicate his findings. This disagreement surrounding the MMR vaccination is likely putting millions of people, mostly children, at risk of contracting horrific diseases. Brian Deer established the fraud in Wakefield’s original study and rejected Wakefield’s null hypothesis. Deer’s seven years of investigation affirmed the countless research studies that rejected Wakefield’s null hypothesis. Deer’s analysis of Dr. Wakefield’s study demonstrates how the public and the media can be blindly misled by scientific studies. When information has reached people’s grasp, it is hard to retract false information once it has permeated millions of households, which is what needs to be accomplished regarding the truth behind the relationship between the MMR vaccination and autism. The medical world could benefit from knowing the cause of this detrimental disorder, in an effort to treat patients better and possibly someday cure them

    Nonlinear optical polymers for electro-optic signal processing

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    Photonics is an emerging technology, slated for rapid growth in communications systems, sensors, imagers, and computers. Its growth is driven by the need for speed, reliability, and low cost. New nonlinear polymeric materials will be a key technology in the new wave of photonics devices. Electron-conjubated polymeric materials offer large electro-optic figures of merit, ease of processing into films and fibers, ruggedness, low cost, and a plethora of design options. Several new broad classes of second-order nonlinear optical polymers were developed at the Navy's Michelson Laboratory at China Lake, California. Polar alignment in thin film waveguides was achieved by electric-field poling and Langmuir-Blodgett processing. Our polymers have high softening temperatures and good aging properties. While most of the films can be photobleached with ultraviolet (UV) light, some have excellent stability in the 500-1600 nm range, and UV stability in the 290-310 nm range. The optical nonlinear response of these polymers is subpicosecond. Electro-optic switches, frequency doublers, light modulators, and optical data storage media are some of the device applications anticipated for these polymers

    Automatic Generation of Minimal Cut Sets

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    A cut set is a collection of component failure modes that could lead to a system failure. Cut Set Analysis (CSA) is applied to critical systems to identify and rank system vulnerabilities at design time. Model checking tools have been used to automate the generation of minimal cut sets but are generally based on checking reachability of system failure states. This paper describes a new approach to CSA using a Linear Temporal Logic (LTL) model checker called BT Analyser that supports the generation of multiple counterexamples. The approach enables a broader class of system failures to be analysed, by generalising from failure state formulae to failure behaviours expressed in LTL. The traditional approach to CSA using model checking requires the model or system failure to be modified, usually by hand, to eliminate already-discovered cut sets, and the model checker to be rerun, at each step. By contrast, the new approach works incrementally and fully automatically, thereby removing the tedious and error-prone manual process and resulting in significantly reduced computation time. This in turn enables larger models to be checked. Two different strategies for using BT Analyser for CSA are presented. There is generally no single best strategy for model checking: their relative efficiency depends on the model and property being analysed. Comparative results are given for the A320 hydraulics case study in the Behavior Tree modelling language.Comment: In Proceedings ESSS 2015, arXiv:1506.0325

    Coding of the Reach Vector in Parietal Area 5d

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    Competing models of sensorimotor computation predict different topological constraints in the brain. Some models propose population coding of particular reference frames in anatomically distinct nodes, whereas others require no such dedicated subpopulations and instead predict that regions will simultaneously code in multiple, intermediate, reference frames. Current empirical evidence is conflicting, partly due to difficulties involved in identifying underlying reference frames. Here, we independently varied the locations of hand, gaze, and target over many positions while recording from the dorsal aspect of parietal area 5. We find that the target is represented in a predominantly hand-centered reference frame here, contrasting with the relative code seen in dorsal premotor cortex and the mostly gaze-centered reference frame in the parietal reach region. This supports the hypothesis that different nodes of the sensorimotor circuit contain distinct and systematic representations, and this constrains the types of computational model that are neurobiologically relevant

    Comparison of satellite based cloud retrieval methods for cirrus and stratocumulus

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    One difficulty in using satellite remote sensing data is the spatial variability of cloud properties on scales smaller than most meteorological satellite fields of view (approx. 4 to 8 km). The variation is examined of satellite derived cloud cover as a function of the satellite sensor spatial resolution for seven cloud cover retrieval methods: (1) Reflectance threshold; (2) Temperature threshold; (3) ISCCP; (4) HBTM (Hybrid Bispectral Threshold Method); (5) NCLE; (6) Spatial coherence; and (7) Functional Box Counting. The first two methods are simple single spectral thresholds which specify a satellite pixel as cloud filled if the measured reflectance is greater than the threshold, or if the measured equivalent blackbody temperature is less than the threshold. The next three methods are bispectral, using one visible wavelength window channel and one thermal infrared wavelength window. The final two algorithms rely on the spatial variability within the cloud field to determine cloud cover. Spatial coherence assumes only that the cloud field occurs in a single layer and that the clouds are optically thick in the infrared window. LANDSAT Thematic Mapper (TM) data is used to test the spatial resolution dependence of the cloud algorithms. The ISCCP bispectral threshold applied to the full resolution data is used as the reference or truth cloud cover, after which the retrieval methods are applied to the spatial resolutions. Studies of the fraction of pixels in the scene at cloud edge, and of the profile of reflectance and temperature near cloud edges indicate an uncertainty in the reference cloud fraction of 1 to 5 percent

    Flexural properties of the equine hoof wall

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    The equine hoof wall is a hard keratinous structure which transmits forces generated when the hoof contacts the ground to the skeleton of the horse. During locomotion, the hoof capsule is known to yield under impact resulting in an inward curvature of the dorsal wall and expansion of the heels. However, whilst researchers have studied the tensile and compressive properties of the hoof wall, there is a lack of data on the flexural properties in different locations around the hoof capsule. In this study the flexural properties and hydration status of the hoof wall was investigated, in two orthogonal directions, in different locations around the hoof capsule. The hoof was divided into three regions: the dorsal-most aspect (toe); the medial and lateral regions (quarters) and the heels caudally. Beams were cut both perpendicular and parallel to the axis of the tubules, termed transverse and longitudinal beams respectively. Differences in the mechanical properties were then investigated using three-point bending tests. There were considerable differences in the mechanical properties around the hoof capsule; transverse beams from the toe were 81% stiffer and 28% stronger than those from the heels. This corresponded with differences in the hydration of the hoof wall; beams from the toe had a lower water content (24.1±0.25%) than those from the heels (28.3±0.37%). Differences in the flexural properties are thought to be largely a result of variation in the water content. Mechanical data are further discussed in relation to variation in the structure and loading of the hoof wall

    Local and regional heterogeneity underlying hippocampal modulation of cognition and mood.

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    While the hippocampus has been classically studied for its role in learning and memory, there is significant support for a role of the HPC in regulating emotional behavior. Emerging research suggests these functions may be segregated along the dorsoventral axis of the HPC. In addition to this regional heterogeneity, within the HPC, the dentate gyrus is one of two areas in the adult brain where stem cells continuously give rise to new neurons. This process can influence and be modulated by the emotional state of the animal, suggesting that adult neurogenesis within the DG may contribute to psychiatric disorders and cognitive abilities. Yet, the exact mechanism by which these newborn neurons influence behavior remains unknown. Here, we will examine the contribution of hippocampal neurogenesis to the output of the HPC, and suggest that the role of neurogenesis may vary along the DV axis. Next, we will review literature indicating that anatomical connectivity varies along the DV axis of the HPC, and that this underlies the functional segregation along this axis. This analysis will allow us to synthesize novel hypotheses for the differential contribution of the HPC to cognition and mood
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