486 research outputs found

    Thermal QCD in a non-uniform magnetic background

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    Off-central heavy-ion collisions are known to feature magnetic fields with magnitudes and characteristic gradients corresponding to the scale of the strong interactions. In this work, we employ equilibrium lattice simulations of the underlying theory, QCD, involving similar inhomogeneous magnetic field profiles to achieve a better understanding of this system. We simulate three flavors of dynamical staggered quarks with physical masses at a range of magnetic fields and temperatures, and extrapolate the results to the continuum limit. Analyzing the impact of the field on the quark condensate and the Polyakov loop, we find non-trivial spatial features that render the QCD medium qualitatively different as in the homogeneous setup, especially at temperatures around the transition. In addition, we construct leading-order chiral perturbation theory for the inhomogeneous background and compare its prediction to our lattice results at low temperature. Our findings will be useful to benchmark effective theories and low-energy models of QCD for a better description of peripheral heavy-ion collisions.Comment: 24 pages, 15 figure

    Análise de qualidade de grãos de milho.

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    RESUMO - Foram utilizadas seis populações de milho (Zea mays L.), sendo duas de grãos do tipo dente opção (uma braquítica), duas de grãos do tipo duro de autofecundação e duas de grãos do tipo duro de meios irmãos. Foram realizadas análises de laboratório, de variância genética e de correlação fenotípica do peso de quinze grãos, percentagem de embrião, de óleo, de proteína e de triptofano. As populações de grãos dentados opacos foram superiores quanto aos conteúdos de óleo, triptofano e valor proteico, enquanto que aquelas com grãos duros de autofecundação mostraram maiores percentagens de proteína, ao passo que as de grãos duros de meios irmãos acusaram maiores possibilidades de incremento através do melhoramento genético, enquanto que a percentagem de proteína apresentou a menor viabilidade. Foram detectadas correlações positivas do conteúdo de óleo com tamanho de embrião e com percentagem de triptofano; e correlação negativa entre peso de grãos e percentagem de proteína. ABSTRACT - Six populations of com (Zea mays L.), including two of dent grain opaque-2 (one braquitic), two self-femtilized flint grain and two half-sib flint grain types were used. Laboratory analyses were made of genetic variance and phenotypic correlations of the weight of 15 grains, percentage of embryo, oil, protein and tryptophan. The opaque-2 dent grain populations were higher in oil content, tryptophan and protein value, and the self-fertilized flint grain populations were higher in protein percentage while the haif-sib flint grain populations showed higher grain weight values. Tryptophan content showed the greatest increase potential through genetic improvement while protein percentage showed the lowest. Positive phenotypic correlations of oil content with embryo sire and with tryptophan percentage were detected and negative correlation was found between grain weight and protein percentageTítulo em inglês: Analysis of grain quality in corn

    A New Perceptual Bias Reveals Suboptimal Population Decoding of Sensory Responses

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    Several studies have reported optimal population decoding of sensory responses in two-alternative visual discrimination tasks. Such decoding involves integrating noisy neural responses into a more reliable representation of the likelihood that the stimuli under consideration evoked the observed responses. Importantly, an ideal observer must be able to evaluate likelihood with high precision and only consider the likelihood of the two relevant stimuli involved in the discrimination task. We report a new perceptual bias suggesting that observers read out the likelihood representation with remarkably low precision when discriminating grating spatial frequencies. Using spectrally filtered noise, we induced an asymmetry in the likelihood function of spatial frequency. This manipulation mainly affects the likelihood of spatial frequencies that are irrelevant to the task at hand. Nevertheless, we find a significant shift in perceived grating frequency, indicating that observers evaluate likelihoods of a broad range of irrelevant frequencies and discard prior knowledge of stimulus alternatives when performing two-alternative discrimination

    Comportamento Preliminar de Alguns Clones de Seringueira.

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    Em três experimentos, em andamento, em áreas do Latossolo Amarelo, textura argilosa, de baixa fertilidade natural, boa profundidade e bem drenado, ocorrente em áreas do Centro Nacional de Pesquisa de Seringueira e Dendê (CNPSD), em Manaus, AM, estio sendo avaliados a produção e o desenvolvimento de 48 clones de seringueira (Hevea spp.) das séries Fx IAN, RRIM e alguns clones primários em diferentes idades. Foi utilizado o delineamento de blocos casualizados em dois ou três experimentos, com 10 e 25 plantas por parcela, respectivamente, com duas repetições, obedecendo ao espaçamento de 7 m x 3 m. 0 terceiro experimento foi delineado em látece tripo 5 x 5, com 20 plantas por parcela. Os resultados indicam que, dos 48 clones estudados, os clones Fx 3899, IAN 717, Fx 4098, IAN 6158 e IAN 6323 estão mostrando o melhor desempenho em relação à produção e ao vigor

    Pennsylvania Folklife Vol. 36, No. 4

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    • The Art of Glass Blowing • Portrait Painting • The Ox Roast • Herbal Soap-Making • Fly-Fishing and Fly-Tying • Chalkware • Silversmithing • Festival Focus • Festival Programs • Coopering • Knife Making • Corn Husk Dolls • Salt Glaze Pottery • Blacksmithing and Iron Working • Bird Carving • Soft Pretzelshttps://digitalcommons.ursinus.edu/pafolklifemag/1116/thumbnail.jp

    The `Parahippocampal Place Area' Responds Selectively to High Spatial Frequencies

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    Defining the exact mechanisms by which the brain processes visual objects and scenes remains an unresolved challenge. Valuable clues to this process have emerged from the demonstration that clusters of neurons (“modules”) in inferior temporal cortex apparently respond selectively to specific categories of visual stimuli, such as places/scenes. However, the higher-order “category-selective” response could also reflect specific lower-level spatial factors. Here we tested this idea in multiple functional MRI experiments, in humans and macaque monkeys, by systematically manipulating the spatial content of geometrical shapes and natural images. These tests revealed that visual spatial discontinuities (as reflected by an increased response to high spatial frequencies) selectively activate a well-known place-selective region of visual cortex (the “parahippocampal place area”) in humans. In macaques, we demonstrate a homologous cortical area, and show that it also responds selectively to higher spatial frequencies. The parahippocampal place area may use such information for detecting object borders and scene details during spatial perception and navigation.National Institutes of Health (U.S.) (NIH Grant R01 MH6752)National Institutes of Health (U.S.) (grant R01 EY017081)Athinoula A. Martinos Center for Biomedical ImagingNational Center for Research Resources (U.S.)Mind Research Institut

    Systematic review and meta-analysis of the diagnostic accuracy of ultrasonography for deep vein thrombosis

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    Background Ultrasound (US) has largely replaced contrast venography as the definitive diagnostic test for deep vein thrombosis (DVT). We aimed to derive a definitive estimate of the diagnostic accuracy of US for clinically suspected DVT and identify study-level factors that might predict accuracy. Methods We undertook a systematic review, meta-analysis and meta-regression of diagnostic cohort studies that compared US to contrast venography in patients with suspected DVT. We searched Medline, EMBASE, CINAHL, Web of Science, Cochrane Database of Systematic Reviews, Cochrane Controlled Trials Register, Database of Reviews of Effectiveness, the ACP Journal Club, and citation lists (1966 to April 2004). Random effects meta-analysis was used to derive pooled estimates of sensitivity and specificity. Random effects meta-regression was used to identify study-level covariates that predicted diagnostic performance. Results We identified 100 cohorts comparing US to venography in patients with suspected DVT. Overall sensitivity for proximal DVT (95% confidence interval) was 94.2% (93.2 to 95.0), for distal DVT was 63.5% (59.8 to 67.0), and specificity was 93.8% (93.1 to 94.4). Duplex US had pooled sensitivity of 96.5% (95.1 to 97.6) for proximal DVT, 71.2% (64.6 to 77.2) for distal DVT and specificity of 94.0% (92.8 to 95.1). Triplex US had pooled sensitivity of 96.4% (94.4 to 97.1%) for proximal DVT, 75.2% (67.7 to 81.6) for distal DVT and specificity of 94.3% (92.5 to 95.8). Compression US alone had pooled sensitivity of 93.8 % (92.0 to 95.3%) for proximal DVT, 56.8% (49.0 to 66.4) for distal DVT and specificity of 97.8% (97.0 to 98.4). Sensitivity was higher in more recently published studies and in cohorts with higher prevalence of DVT and more proximal DVT, and was lower in cohorts that reported interpretation by a radiologist. Specificity was higher in cohorts that excluded patients with previous DVT. No studies were identified that compared repeat US to venography in all patients. Repeat US appears to have a positive yield of 1.3%, with 89% of these being confirmed by venography. Conclusion Combined colour-doppler US techniques have optimal sensitivity, while compression US has optimal specificity for DVT. However, all estimates are subject to substantial unexplained heterogeneity. The role of repeat scanning is very uncertain and based upon limited data

    A neural signature of the unique hues

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    Since at least the 17th century there has been the idea that there are four simple and perceptually pure “unique” hues: red, yellow, green, and blue, and that all other hues are perceived as mixtures of these four hues. However, sustained scientific investigation has not yet provided solid evidence for a neural representation that separates the unique hues from other colors. We measured event-related potentials elicited from unique hues and the ‘intermediate’ hues in between them. We find a neural signature of the unique hues 230 ms after stimulus onset at a post-perceptual stage of visual processing. Specifically, the posterior P2 component over the parieto-occipital lobe peaked significantly earlier for the unique than for the intermediate hues (Z = -2.9, p = .004). Having identified a neural marker for unique hues, fundamental questions about the contribution of neural hardwiring, language and environment to the unique hues can now be addressed
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