1,376 research outputs found

    Influence of particle density on flow behavior and deposit architecture of concentrated pyroclastic density currents over a break in slope: Insights from laboratory experiments

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    Geological granular flows are highly complex, gravity-driven phenomena whose different behaviors depend on the mechanical properties, density and granulometric distributions of the constituent materials. Years of research have produced significant advances in understanding transport and deposition processes in granular flows. However, the role and effects of clast densities and density contrast in a granular flow are still not fully understood. In this paper we show the effect that pumice has on dry granular flows; specifically on flow velocity and longitudinal segregation of the deposits. Our work confirms, by experimental results, field observations on pumice/lithic segregation and longer pumice runout. We report results of velocity decay and deposit architecture for a granular flow passing over a break in slope (from 38° to 4° inclination). The 30 experimental runs were carried out in a five-meter long laboratory flume equipped with a series of sensors that include laser gates and high-speed cameras (400 fps). We used two polydisperse mixtures of dacitic lithics and rhyolitic pumice in varying amounts, with Weibull and Gaussian particle size distributions. The pumice/lithic ratio changes the flow response passing over a break in slope. This effect is particularly evident starting from 10% of pumice volume into the flow mixture, independently of its granulometric distribution. Runout relates to mass following a power law, with an exponent close 0.2. The experiments confirm that pumice segregation affects polydispersed mixtures, similarly to what has been observed in real field deposits, where density decoupling produces lithic-enriched proximal areas and pumice-enriched distal areas. The results obtained prove that the presence of low-density materials in a dense granular flow has a strong influence on its behavior

    Spatial effects on species persistence and implications for biodiversity

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    Natural ecosystems are characterized by striking diversity of form and functions and yet exhibit deep symmetries emerging across scales of space, time and organizational complexity. Species-area relationships and species-abundance distributions are examples of emerging patterns irrespective of the details of the underlying ecosystem functions. Here we present empirical and theoretical evidence for a new macroecological pattern related to the distributions of local species persistence times, defined as the timespans between local colonizations and extinctions in a given geographic region. Empirical distributions pertaining to two different taxa, breeding birds and herbaceous plants, analyzed in a new framework that accounts for the finiteness of the observational period, exhibit power-law scaling limited by a cut-off determined by the rate of emergence of new species. In spite of the differences between taxa and spatial scales of analysis, the scaling exponents are statistically indistinguishable from each other and significantly different from those predicted by existing models. We theoretically investigate how the scaling features depend on the structure of the spatial interaction network and show that the empirical scaling exponents are reproduced once a two-dimensional isotropic texture is used, regardless of the details of the ecological interactions. The framework developed here also allows to link the cut-off timescale with the spatial scale of analysis, and the persistence-time distribution to the species-area relationship. We conclude that the inherent coherence obtained between spatial and temporal macroecological patterns points at a seemingly general feature of the dynamical evolution of ecosystems.Comment: 5 pages, 5 figures. Supplementary materials avaliable on http://www.pnas.org/content/108/11/434

    Machine-assisted Cyber Threat Analysis using Conceptual Knowledge Discovery

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    Over the last years, computer networks have evolved into highly dynamic and interconnected environments, involving multiple heterogeneous devices and providing a myriad of services on top of them. This complex landscape has made it extremely difficult for security administrators to keep accurate and be effective in protecting their systems against cyber threats. In this paper, we describe our vision and scientific posture on how artificial intelligence techniques and a smart use of security knowledge may assist system administrators in better defending their networks. To that end, we put forward a research roadmap involving three complimentary axes, namely, (I) the use of FCA-based mechanisms for managing configuration vulnerabilities, (II) the exploitation of knowledge representation techniques for automated security reasoning, and (III) the design of a cyber threat intelligence mechanism as a CKDD process. Then, we describe a machine-assisted process for cyber threat analysis which provides a holistic perspective of how these three research axes are integrated together

    Quantification of impacts in artistic gymnastics with accelerometry: an approximation

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    Intensity and volume of training in Artisti Gymnastics are increasing as the sooner athlete's age of incorporation creating some disturbance in them

    Protective effects of eicosapentaenoic acid plus hydroxytyrosol supplementation against white adipose tissue abnormalities in mice fed a high-fat diet

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    Objective: Obesity induced by high-fat diet (HFD) elicits white adipose tissue dysfunction. In this study, we have hypothesized that the metabolic modulator eicosapentaenoic acid (EPA) combined with the antioxidant hydroxytyrosol (HT) attenuates HFD-induced white adipose tissue (WAT) alterations. Methods: C57BL/6J mice were administered with a HFD (60% fat, 20% protein, 20% carbohydrates) or control diet (CD; 10% fat, 20% protein, 70% carbohydrates), with or without EPA (50 mg/kg/day), HT (5 mg/kg/day), or both for 12 weeks. Determinations in WAT include morphological parameters, EPA and docosahexaenoic acid content in phospholipids (gas chromatography), lipogenesis, oxidative stress (OS) and inflammation markers, and gene expression and activities of transcription factors, such as sterol regulatory element-binding protein-1c (SREBP-1c), peroxisome proliferator-activated receptor-gamma (PPAR-Îł), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ÎşB) (p65 subunit) and nuclear factor erythroid 2-related factor 2 (Nrf2) (quantitative polymerase chain reaction and enzyme linked immunosorbent assay). Results: HFD led to WAT hypertrophy in relation to PPAR-Îł downregulation. WAT metabolic dysfunction was characterized by upregulation of lipogenic SREBP-1c system, mitochondrial energy metabolism depression, loss of the antioxidant Nrf2 signaling with OS enhancement, n-3 long-chain polyunsaturated fatty acids depletion and activation of the pro-inflammatory NF-ÎşB system. EPA and HT co-supplementation diminished HFD-dependent effects additively, reaching values close or similar to controls. Conclusion: Data presented strengthen the importance of combined protocols such as EPA plus HT to attenuate metabolic-inflammatory states triggered by obesity

    Potencial forrageiro de seis hĂ­bridos de sorgo com capim sudĂŁo.

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    Avaliaram-se quatro híbridos experimentais e duas cultivares comerciais de Sorghum bicolor cv bicolor x Sorghum bicolor cv sudanense quanto às características agronômicas: produções de matéria verde por hectare (MV/ha), matéria seca (MS/ha), altura das plantas, número de plantas/ha, taxa de rebrota e relação folha/haste. Os plantios ocorreram na transição do período seco para o período chuvoso. Os híbridos foram submetidos a três cortes sucessivos, realizados em duas épocas de plantio. Foi empregado um delineamento experimental de blocos ao acaso e a comparação de médias foi efetuada pelo teste de SNK, a 5% de probabilidade. Os híbridos estudados não diferiram para a maioria das características avaliadas, com exceção da população de plantas, em que o híbrido experimental ATF 54 x CMSXS 912, com 848 mil plantas/há, foi semelhante (P>0,05) aos híbridos testemunhas (comerciais) AG2501C, com 780 mil plantas/ha, e ao BRS800, com 749 mil plantas/ha, sendo superior (P<0,05) aos demais híbridos. Os resultados de produtividade indicam o potencial dos híbridos de sorgo com capim Sudão estudados para serem utilizados como alternativa para a produção de forragem em regime de corte, na transição do período seco para o período chuvoso

    Avaliação da silagem do híbrido de sorgo BR 601 com aditivos: alterações nos teores de matéria seca, frações fibrosas e digestibilidade "in vitro" da matéria seca.

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    Avaliou-se o padrão de fermentação de silagens do híbrido de sorgo forrageiro BR 601 com ou sem aditivos. Foram adotados os tratamentos: silagem sem aditivo (testemunha) e silagens adicionadas com 0,5% de uréia, 0,5% de carbonato de cálcio, 0,5% de uréia mais 0,5% de carbonato de cálcio e com inoculante bacteriano. Os materiais foram ensilados em silos de “PVC” e abertos com um, três, cinco, sete, 14, 28 e 56 dias de ensilagem. Determinaram-se as variações nos teores de matéria seca (MS), os teores de fibra em detergente neutro (FDN), hemicelulose, celulose, fibra em detergente ácido (FDA), lignina e a digestibilidade “in vitro” da MS (DIVMS). Adotou-se o delineamento inteiramente casualizado, em um esquema fatorial 5 x 7, sendo as médias comparadas pelo teste SNK a 5%. As silagens tratadas com a associação entre uréia e carbonato de cálcio apresentaram as maiores perdas de MS. Os aditivos não promoveram alterações nos teores de FDN, hemicelulose e celulose e na DIVMS. Ocorreu diferença entre a silagem testemunha e as silagens com aditivo, com a evolução do processo fermentativo, quanto aos teores de FDA e lignina

    Qualidade nutricional de seis hĂ­bridos de sorgo com capim sudĂŁo submetidos a Ă©pocas de plantio e cortes distintas.

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    Foram avaliados quatro híbridos experimentais (ATF 54 x CMSXS 912, CMSXS 156 x CMSXS 912, CMSXS 157 x CMSXS 912 e CMSXS 210 x CMSXS 912) e duas cultivares comerciais de Sorghum bicolor cv bicolor X Sorghum bicolor cv sudanense (AG2501C e BRS800) quanto ao valor nutritivo: produções de MS digestível (MSD t/ha), digestibilidade in vitro da MS (DIVMS%), proteína bruta (PB%), fibra em detergente neutro (FDN%), fibra em detergente ácido (FDA%), fósforo (P%) e cálcio (Ca%). Os híbridos foram submetidos a três cortes sucessivos e o plantio foi realizado em duas épocas diferentes. O delineamento experimental foi o de blocos ao acaso e a comparação de médias foi efetuada pelo teste de SNK, a 5% de probabilidade. Os híbridos ATF 54 x CMSXS 912 e AG 2501-C apresentaram valores médios de produção 1,28 t de MSD/ha superiores nas duas épocas de plantio. Ocorreram diferenças entre os híbridos quanto aos teores de PB, com valor médio de 16,33%, Ca com valores entre 0,42% e 0,49% e teores de P com valor médio de 0,26%. O híbrido BRS 800 foi superior (p<0,05) quanto ao teor médio de P (0,28%), teor médio de PB (17,32%), sendo semelhante ao híbrido CMSXS 210 x CMSXS 912, que obteve o valor de 16,75%

    Skin Bioimpedance Analysis to Determine Cellular Integrity by Phase Angle in Women with Fibromyalgia: A Cross-Sectional Study.

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    Oxidative stress has been proposed as a significant part of the pathogenesis of fibromyalgia, and the phase angle in bioelectrical impedance analysis has been explored as a potential technique to screen oxidative abnormalities. This study recruited 35 women with fibromyalgia and 35 healthy women, who underwent bioelectrical impedance analysis and maximum isometric handgrip strength tests. Women with fibromyalgia showed lower bilateral handgrip strength (right hand: 16.39 ± 5.87 vs. 27.53 ± 4.09, p < 0.001; left hand: 16.31 ± 5.51 vs. 27.61 ± 4.14, p < 0.001), as well as higher body fat mass (27.14 ± 10.21 vs. 19.94 ± 7.25, p = 0.002), body fat percentage (37.80 ± 8.32 vs. 30.63 ± 7.77, p < 0.001), and visceral fat area (136.76 ± 55.31 vs. 91.65 ± 42.04, p < 0.01) compared with healthy women. There was no statistically significant difference in muscle mass between groups, but women with fibromyalgia showed lower phase angles in all body regions when compared with healthy control women (right arm: 4.42 ± 0.51 vs. 4.97 ± 0.48, p < 0.01; left arm: 4.23 ± 0.48 vs. 4.78 ± 0.50, p < 0.001; trunk: 5.62 ± 0.77 vs. 6.78 ± 0.84, p < 0.001; right leg: 5.28 ± 0.56 vs. 5.81 ± 0.60, p < 0.001; left leg: 5.07 ± 0.51 vs. 5.69 ± 0.58, p < 0.001; whole body: 4.81 ± 0.47 vs. 5.39 ± 0.49, p < 0.001). Moreover, whole-body phase-angle reduction was only predicted by the presence of fibromyalgia (R 2 = 0.264; β = 0.639; F(1,68) = 24.411; p < 0.001). Our study revealed significantly lower phase angle values, lower handgrip strength, and higher fat levels in women with fibromyalgia compared to healthy controls, which are data of clinical relevance when dealing with such patients.post-print1,25 M
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