396 research outputs found

    Does combining aspirin and warfarin decrease the risk of stroke for patients with nonvalvular atrial fibrillation?

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    Adjusted-dose warfarin (international normalized ratio [INR]=2.0-3.0) remains the most efficacious antithrombotic regimen for the primary and secondary prevention of cardioembolic stroke in high-risk patients with nonvalvular atrial fibrillation (NVAF) (strength of recommendation [SOR]: A, based on randomized controlled trials). Aspirin therapy at a dose of 75 to 325 mg reduces the risk of stroke to a lesser degree and may be useful for low-risk patients with NVAF or patients at high risk for bleeding (SOR: A, based on randomized controlled trials). Combination therapy with low, fixed-dose warfarin (1-2 mg) and aspirin has not been shown to be superior to aspirin therapy alone. Moreover, this combination appears to be inferior to adjusted-dose warfarin (SOR: A, based on randomized controlled trials). To date, no clinical trials have investigated the efficacy and safety of combining adjusted-dose warfarin and aspirin for the prevention of stroke from NVAF

    Microwave-Spectral Signatures Would Reveal Concealed Objects

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    A proposed technique for locating concealed objects (especially small antipersonnel land mines) involves the acquisition and processing of spectral signatures over broad microwave frequency bands. This technique was conceived to overcome the weaknesses of older narrow- band electromagnetic techniques like ground-probing radar and low-frequency electromagnetic induction. Ground-probing radar is susceptible to false detections and/or interference caused by rocks, roots, air pockets, soil inhomogeneities, ice, liquid water, and miscellaneous buried objects other than those sought. Moreover, if the radar frequency happens to be one for which the permittivity of a sought object matches the permittivity of the surrounding soil or there is an unfavorable complex-amplitude addition of the radar reflection at the receiver, then the object is not detected. Low-frequency electromagnetic induction works well for detecting metallic objects, but the amounts of metal in plastic mines are often too small to be detectable. The potential advantage of the proposed technique arises from the fact that wideband spectral signatures generally contain more relevant information than do narrow-band signals. Consequently, spectral signatures could be used to make better decisions regarding whether concealed objects are present and whether they are the ones sought. In some cases, spectral signatures could provide information on the depths, sizes, shapes, and compositions of objects. An apparatus to implement the proposed technique (see Figure 1) could be assembled from equipment already in common use. Typically, such an apparatus would include a radio-frequency (RF) transmitter/receiver, a broad-band microwave antenna, and a fast personal computer loaded with appropriate software. In operation, the counter would be turned on, the antenna would be aimed at the ground or other mass suspected to contain a mine or other sought object, and the operating frequency would be swept over the band of interest

    Geographic variation in phenotypic divergence between two hybridizing field cricket species

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    Patterns of morphological divergence across species' ranges can provide insight into local adaptation and speciation. In this study, we compared phenotypic divergence among 4,221 crickets from 337 populations of two closely related species of field cricket, Gryllus firmus and G. pennsylvanicus, and their hybrids. We found that these species differ across their geographic range in key morphological traits, such as body size and ovipositor length, and we directly compared phenotype with genotype for a subset of crickets to demonstrate nuclear genetic introgression, phenotypic intermediacy of hybrids, and essentially unidirectional mitochondrial introgression. We discuss how these morphological traits relate to life history differences between the two species. Our comparisons across geographic areas support prior research suggesting that cryptic variation within G. firmus may represent different species. Our study highlights how variable morphology can be across wide-ranging species and the importance of studying reproductive barriers in more than one or two transects of a hybrid zone

    Methods and apparatus for microwave tissue welding for wound closure

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    Methods and apparatus for joining biological tissue together are provided. In at least one specific embodiment, a method for joining biological tissue together can include applying a biological solder on a wound. A barrier layer can be disposed on the biological solder. An antenna can be located in proximate spatial relationship to the barrier layer. An impedance of the antenna can be matched to an impedance of the wound. Microwaves from a signal generator can be transmitted through the antenna to weld two or more biological tissue pieces of the wound together. A power of the microwaves can be adjusted by a control circuit disposed between the antenna and the signal generator. The heating profile within the tissue may be adjusted and controlled by the placement of metallic microspheres in or around the wound

    Clock drawing performance in cognitively normal elderly

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    The Clock Drawing Test (CDT) is a common neuropsychological measure sensitive to cognitive changes and functional skills (e.g., driving test performance) among older adults. However, normative data have not been adequately developed. We report the distribution of CDT scores using three common scoring systems [Mendez, M. F., Ala, T., & Underwood, K. L. (1992). Development of scoring criteria for the Clock Drawing Task in Alzheimer's Disease. Journal of the American Geriatrics Society, 40, 1095-1099; Cahn, D. A., Salmon, D. P., Monsch, A. U., Butters, N., Wiederholt, W. C., & Corey-Bloom, J. (1996). Screening for dementia of the Alzheimer type in the community: The utility of the Clock Drawing Test. Archives of Clinical Neuropsychology, 11(6), 529-539], among 207 cognitively normal elderly. The systems were well correlated, took little time to use, and had high inter-rater reliability. We found statistically significant differences in CDT scores based on age and WRAT-3 Reading score, a marker of education quality. We present means, standard deviations, and t- and z-scores based on these subgroups. We found that "normal" CDT performance includes a wider distribution of scores than previously reported. Our results may serve as useful comparisons for clinicians wishing to know whether their patients perform in the general range of cognitively normal elderly. © 2007 National Academy of Neuropsychology

    Two-Center Integrals for r_{ij}^{n} Polynomial Correlated Wave Functions

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    All integrals needed to evaluate the correlated wave functions with polynomial terms of inter-electronic distance are included. For this form of the wave function, the integrals needed can be expressed as a product of integrals involving at most four electrons

    YAP/TAZ-CDC42 signaling regulates vascular tip cell migration

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    Angiogenesis and vascular remodeling are essential for the establishment of vascular networks during organogenesis. Here we show that the Hippo signaling pathway effectors YAP and TAZ are required, in a gene dosage-dependent manner, for the proliferation and migration of vascular endothelial cells (ECs) during retinal angiogenesis. Intriguingly, nuclear translocation of YAP and TAZ induced by Lats1/2-deletion blocked endothelial migration and phenocopied Yap/Taz-deficient mutants. Furthermore, overexpression of a cytoplasmic form of YAP (YAPS127D) partially rescued the migration defects caused by loss of YAP and TAZ function. Finally, we found that cytoplasmic YAP positively regulated the activity of the small GTPase CDC42, deletion of which caused severe defects in endothelial migration. These findings uncover a previously unrecognized role of cytoplasmic YAP/TAZ in promoting cell migration by activating CDC42 and provide insight into how Hippo signaling in ECs regulates angiogenesis

    Hormonal Signal Amplification Mediates Environmental Conditions during Development and Controls an Irreversible Commitment to Adulthood

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    Many animals can choose between different developmental fates to maximize fitness. Despite the complexity of environmental cues and life history, different developmental fates are executed in a robust fashion. The nematode Caenorhabditis elegans serves as a powerful model to examine this phenomenon because it can adopt one of two developmental fates (adulthood or diapause) depending on environmental conditions. The steroid hormone dafachronic acid (DA) directs development to adulthood by regulating the transcriptional activity of the nuclear hormone receptor DAF-12. The known role of DA suggests that it may be the molecular mediator of environmental condition effects on the developmental fate decision, although the mechanism is yet unknown. We used a combination of physiological and molecular biology techniques to demonstrate that commitment to reproductive adult development occurs when DA levels, produced in the neuroendocrine XXX cells, exceed a threshold. Furthermore, imaging and cell ablation experiments demonstrate that the XXX cells act as a source of DA, which, upon commitment to adult development, is amplified and propagated in the epidermis in a DAF-12 dependent manner. This positive feedback loop increases DA levels and drives adult programs in the gonad and epidermis, thus conferring the irreversibility of the decision. We show that the positive feedback loop canalizes development by ensuring that sufficient amounts of DA are dispersed throughout the body and serves as a robust fate-locking mechanism to enforce an organism-wide binary decision, despite noisy and complex environmental cues. These mechanisms are not only relevant to C. elegans but may be extended to other hormonal-based decision-making mechanisms in insects and mammals

    ADEOS Total Ozone Mapping Spectrometer (TOMS) Data Products User's Guide

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    Two data products from the Total Ozone Mapping Spectrometer (ADEOS/TOMS) have been archived at the Distributed Active Archive Center, in the form of Hierarchical Data Format files. The ADEOS/ TOMS began taking measurements on September 11, 1996, and ended on June 29, 1997. The instrument measured backscattered Earth radiance and incoming solar irradiance; their ratio was used in ozone retrievals. Changes in the reflectivity of the solar diffuser used for the irradiance measurement were monitored using a carousel of three diffusers, each exposed to the degrading effects of solar irradiation at different rates. The algorithm to retrieve total column ozone compares measured Earth radiances at sets of three wavelengths with radiances calculated for different total ozone values, solar zenith angles, and optical paths. The initial error in the absolute scale for TOMS total ozone is 3 percent, the one standard deviation random error is 2 percent, and the drift is less than 0.5 percent over the 9-month data record. The Level 2 product contains the measured radiances, the derived total ozone amount, and reflectivity information for each scan position. The Level 3 product contains daily total ozone and reflectivity in a 1-degree latitude by 1.25 degrees longitude grid. The Level 3 files containing estimates of UVB at the Earth surface and tropospheric aerosol information will also be available. Detailed descriptions of both HDF data files and the CDROM product are provided
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