533 research outputs found

    Adaptive array antenna for satellite cellular and direct broadcast communications

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    Adaptive phased-array antennas provide cost-effective implementation of large, light weight apertures with high directivity and precise beamshape control. Adaptive self-calibration allows for relaxation of all mechanical tolerances across the aperture and electrical component tolerances, providing high performance with a low-cost, lightweight array, even in the presence of large physical distortions. Beam-shape is programmable and adaptable to changes in technical and operational requirements. Adaptive digital beam-forming eliminates uplink contention by allowing a single electronically steerable antenna to service a large number of receivers with beams which adaptively focus on one source while eliminating interference from others. A large, adaptively calibrated and fully programmable aperture can also provide precise beam shape control for power-efficient direct broadcast from space. Advanced adaptive digital beamforming technologies are described for: (1) electronic compensation of aperture distortion, (2) multiple receiver adaptive space-time processing, and (3) downlink beam-shape control. Cost considerations for space-based array applications are also discussed

    Adposition and Case Supersenses v2.5: Guidelines for English

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    This document offers a detailed linguistic description of SNACS (Semantic Network of Adposition and Case Supersenses; Schneider et al., 2018), an inventory of 50 semantic labels ("supersenses") that characterize the use of adpositions and case markers at a somewhat coarse level of granularity, as demonstrated in the STREUSLE corpus (https://github.com/nert-gu/streusle/; version 4.3 tracks guidelines version 2.5). Though the SNACS inventory aspires to be universal, this document is specific to English; documentation for other languages will be published separately. Version 2 is a revision of the supersense inventory proposed for English by Schneider et al. (2015, 2016) (henceforth "v1"), which in turn was based on previous schemes. The present inventory was developed after extensive review of the v1 corpus annotations for English, plus previously unanalyzed genitive case possessives (Blodgett and Schneider, 2018), as well as consideration of adposition and case phenomena in Hebrew, Hindi, Korean, and German. Hwang et al. (2017) present the theoretical underpinnings of the v2 scheme. Schneider et al. (2018) summarize the scheme, its application to English corpus data, and an automatic disambiguation task

    Processamento de orações relativas de objeto direto com pronomes resumptivos: o caso do Português Brasileiro e o efeito de lacuna preenchida

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    Este artigo apresenta os achados de um experimento de leitura automonitorada com orações relativas de objeto direto com pronomes resumptivos (PRs) no português brasileiro (PB). Há relatos mistos sobre o processamento/aceitabilidade de PRs comparado a relativas com lacunas (MELTZER-ASSCHER, 2021), mesmo em línguas em que PRs são gramaticalmente requeridos em algumas relativas, como no hebraico. No PB, a relativa do tipo resumptivo é uma variante menos frequente e geralmente estigmatizada (MOLLICA, 1977). Nossos resultados indicam que a presença de um PR parece impor um efeito de lacuna preenchida, que se distingue daquele causado por um DP agramatical, e do qual o processamento se recupera rapidamente, evidenciado por tempos de leitura iguais aos da lacuna gramatical em segmentos seguintes. A comparação com um pronome reto em orações completivas sugere que o custo do PR não se deve à presença do pronome em si, mas à alta previsibilidade da lacuna em orações relativas de baixa complexidade

    Comparing neural correlates of conditioned inhibition between children with and without anxiety disorders - A preliminary study

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    Cognitive-behavioral therapy (CBT), a first-line treatment for pediatric anxiety disorders, is based on principles of threat learning and extinction. However, CBT does not work sufficiently for up to 40% of clinically anxious youth. The neural and behavioral correlates of conditioned inhibition might provide promising targets for attempts to improve CBT response. During conditioned inhibition, threat and safety cues appear together, forming a safety compound. Here, we test whether this safety compound elicits a reduced fear response compared to pairing the threat cue with a novel cue (novel compound). The current pilot study compares behavioral, physiological, and neural correlates of conditioned inhibition between children with (n=17, Mage=13.09, SD=3.05) and without (n=18, Mage=14.49, SD=2.38) anxiety disorders. Behavioral and physiological measures did not differ between children with and without anxiety disorders during fear acquisition. During testing, children with anxiety disorders showed overall higher skin conductance response and expected to hear the aversive sound following the novel compound more often than children without anxiety disorders. Children with anxiety disorders showed more activity in the right ventromedial prefrontal cortex (vmPFC) to the safety versus novel compound. Children without anxiety disorders showed the opposite pattern - more right vmPFC activity to the novel versus safety compound (F(1,31)=5.40, p=0.03). No group differences manifested within the amygdala, dorsal anterior cingulate cortex, or hippocampus. These pilot findings suggest a feasible approach for examining conditioned inhibition in pediatric anxiety disorders. If replicated in larger samples, findings may implicate perturbed conditioned inhibition in pediatric anxiety disorders and provide targets for CBT

    Comparison of established and emerging biodosimetry assays

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    Rapid biodosimetry tools are required to assist with triage in the case of a large-scale radiation incident. Here, we aimed to determine the dose-assessment accuracy of the well-established dicentric chromosome assay (DCA) and cytokinesis-block micronucleus assay (CBMN) in comparison to the emerging γ-H2AX foci and gene expression assays for triage mode biodosimetry and radiation injury assessment. Coded blood samples exposed to 10 X-ray doses (240 kVp, 1 Gy/min) of up to 6.4 Gy were sent to participants for dose estimation. Report times were documented for each laboratory and assay. The mean absolute difference (MAD) of estimated doses relative to the true doses was calculated. We also merged doses into binary dose categories of clinical relevance and examined accuracy, sensitivity and specificity of the assays. Dose estimates were reported by the first laboratories within 0.3-0.4 days of receipt of samples for the γ-H2AX and gene expression assays compared to 2.4 and 4 days for the DCA and CBMN assays, respectively. Irrespective of the assay we found a 2.5-4-fold variation of interlaboratory accuracy per assay and lowest MAD values for the DCA assay (0.16 Gy) followed by CBMN (0.34 Gy), gene expression (0.34 Gy) and γ-H2AX (0.45 Gy) foci assay. Binary categories of dose estimates could be discriminated with equal efficiency for all assays, but at doses ≥1.5 Gy a 10% decrease in efficiency was observed for the foci assay, which was still comparable to the CBMN assay. In conclusion, the DCA has been confirmed as the gold standard biodosimetry method, but in situations where speed and throughput are more important than ultimate accuracy, the emerging rapid molecular assays have the potential to become useful triage tools

    Obesity and the Risk of Papillary Thyroid Cancer: A Pooled Analysis of Three Case-Control Studies.

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    Background: There is a correlation between temporal trends of obesity prevalence and papillary thyroid cancer (PTC) incidence in the United States. Obesity is a well-recognized risk factor for many cancers, but there are few studies on the association between obesity and PTC risk. We investigated the association between anthropometric measurements and PTC risk using pooled individual data from three case–control populations. Methods: Height and weight information were obtained from three independent case–control studies, including 1917 patients with PTC (1360 women and 557 men) and 2127 cancer-free controls from the United States, Italy, and Germany. Body mass index (BMI), body fat percentage, and body surface area (BSA) were calculated. An unconditional logistic regression model was used to calculate odds ratios (ORs) and confidence intervals (CIs) with respect to risk of PTC, adjusted by age, sex, race/ethnicity, and study site. Results: In the pooled population, for both men and women, an increased risk of PTC was found to be associated with greater weight, BMI, body fat percentage, and BSA, whereas a reduced risk of PTC was associated with greater height, in the pooled population for both men and women. Compared with normal-weight subjects (BMI 18.5–24.9 kg/m2), the ORs for overweight (BMI 25–29.9 kg/m2) and obese (BMI ‡ 30 kg/m2) subjects were 1.72 [CI 1.48–2.00] and 4.17 [CI 3.41–5.10] respectively. Compared with the lowest quartile of body fat percentage, the ORs for the highest quartile were 3.83 [CI 2.85–5.15] in women and 4.05 [CI 2.67– 6.15] in men. Conclusion: Anthropometric factors, especially BMI and body fat percentage, were significantly associated with increased risk of PTC. Future studies of anthropometric factors and PTC that incorporate intermediate factors, including adiposity and hormone biomarkers, are essential to help clarify potential mechanisms of the relationship

    Attentive Learning of Sequential Handwriting Movements: A Neural Network Model

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    Defense Advanced research Projects Agency and the Office of Naval Research (N00014-95-1-0409, N00014-92-J-1309); National Science Foundation (IRI-97-20333); National Institutes of Health (I-R29-DC02952-01)
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