5,426 research outputs found

    The scenario of two-dimensional instabilities of the cylinder wake under EHD forcing: A linear stability analysis

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    We propose to study the stability properties of an air flow wake forced by a dielectric barrier discharge (DBD) actuator, which is a type of electrohydrodynamic (EHD) actuator. These actuators add momentum to the flow around a cylinder in regions close to the wall and, in our case, are symmetrically disposed near the boundary layer separation point. Since the forcing frequencies, typical of DBD, are much higher than the natural shedding frequency of the flow, we will be considering the forcing actuation as stationary. In the first part, the flow around a circular cylinder modified by EHD actuators will be experimentally studied by means of particle image velocimetry (PIV). In the second part, the EHD actuators have been numerically implemented as a boundary condition on the cylinder surface. Using this boundary condition, the computationally obtained base flow is then compared with the experimental one in order to relate the control parameters from both methodologies. After validating the obtained agreement, we study the Hopf bifurcation that appears once the flow starts the vortex shedding through experimental and computational approaches. For the base flow derived from experimentally obtained snapshots, we monitor the evolution of the velocity amplitude oscillations. As to the computationally obtained base flow, its stability is analyzed by solving a global eigenvalue problem obtained from the linearized Navier–Stokes equations. Finally, the critical parameters obtained from both approaches are compared

    Analysis of Ethane Emission Trends from Active Goaf Seals at Mandalong Mine

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    Monitoring of active goaf seals at Mandalong Mine shows anomalous levels of ethane concentrations. Currently ethane concentrations exceeding 250 ppm have been experienced from 30 to 32 C/T seals of MG8 with the remainder of the panel averaging 50 - 100 ppm. Active goaf seals for MG7 and MG9 average 50 - 100 ppm and 80 - 100 ppm, respectively. For most mines these concentrations of ethane would be assumed to indicate a spontaneous combustion event; however no carbon monoxide is being recorded and a sympathetic relationship with methane indicates that the measured ethane is due to gas desorption. This paper presents the results from the mine showing trends in ethane emissions from the active goaf seals to date, and shows how this historical data can be used to predict expected ethane concentrations in the active goaf of MG10

    Human Sexual Cycles are Driven by Culture and Match Collective Moods

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    It is a long-standing question whether human sexual and reproductive cycles are affected predominantly by biology or culture. The literature is mixed with respect to whether biological or cultural factors best explain the reproduction cycle phenomenon, with biological explanations dominating the argument. The biological hypothesis proposes that human reproductive cycles are an adaptation to the seasonal cycles caused by hemisphere positioning, while the cultural hypothesis proposes that conception dates vary mostly due to cultural factors, such as vacation schedule or religious holidays. However, for many countries, common records used to investigate these hypotheses are incomplete or unavailable, biasing existing analysis towards primarily Christian countries in the Northern Hemisphere. Here we show that interest in sex peaks sharply online during major cultural and religious celebrations, regardless of hemisphere location. This online interest, when shifted by nine months, corresponds to documented human birth cycles, even after adjusting for numerous factors such as language, season, and amount of free time due to holidays. We further show that mood, measured independently on Twitter, contains distinct collective emotions associated with those cultural celebrations, and these collective moods correlate with sex search volume outside of these holidays as well. Our results provide converging evidence that the cyclic sexual and reproductive behavior of human populations is mostly driven by culture and that this interest in sex is associated with specific emotions, characteristic of, but not limited to, major cultural and religious celebrations.Comment: Main Paper: 21 pages, 4 figures Supplementary Material: 66 pages, 15 figures, 13 table

    Ferida da moda: epidemiologia, diagnóstico, tratamento e experiência com eqüinos infectados no Pantanal.

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    A pitiose é uma doença granulomatosa que atinge eqüinos, caninos, bovinos, felinos e humanos e ocorre em áreas tropicais, subtropicais ou temperadas (Meireles et al., 1993; Mendoza et al., 1996), causada pelo omiceto Pythium insidiosum (De Cock et al., 1987). A espécie eqüina é a mais atingida, principalmente nas formas cutânea e subcutânea, seguida dos caninos (Mendoza et al., 1996). A enfermidade em eqüinos caracteriza-se pela formação de granulomas eosinofílicos, com a presença de massas necróticas chamadas de kunkers (Mendoza e Alfaro, 1986; Meireles et al., 1993). Em humanos, a doença é mais comum no sudeste asiático, caracterizando-se por formas sistêmicas com arterites e também formas oftálmicas e subcutâneas, sendo as duas últimas associadas a a e b-talassemias (Imwidthaya, 1994; Imwidthaya, 1995). Vários tratamentos têm sido utilizados, principalmente em eqüinos, incluindo tratamento químico (antifúngicos), cirúrgico e imunoterápico. A imunoterapia, proposta inicialmente por Miller (1981), surgiu como uma alternativa concreta para o controle da doença e tem apresentado resultados promissores (Monteiro, 1999). Pythium insidiosum; Epidemiologia; Pitiose nos eqüinos; Imunoterapia; Diagnóstico; Tratamento; Experiência no Pantanal; Pitiose em bovinos; Pitiose experimental; Perspecivas para o controle da pitiose.bitstream/item/79509/1/COT34.pd

    Retorno da atividade reprodutiva pós-parto em ovelhas deslanadas.

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    Spin-orbit mode transfer via a classical analog of quantum teleportation

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    We translate the quantum teleportation protocol into a sequence of coherent operations involving three degrees of freedom of a classical laser beam. The protocol, which we demonstrate experimentally, transfers the polarisation state of the input beam to the transverse mode of the output beam. The role of quantum entanglement is played by a non-separable mode describing the path and transverse degrees of freedom. Our protocol illustrates the possibility of new optical applications based on this intriguing classical analogue of quantum entanglement.Comment: 5 pages, 7 figure

    Neuronal Activity Induces Synaptic Delivery of hnRNP A2/B1 by a BDNF-Dependent Mechanism in Cultured Hippocampal Neurons

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    Dendritic protein synthesis plays a critical role in several forms of synaptic plasticity, including BDNF (brain-derived neurotrophic factor)-mediated long-term synaptic potentiation (LTP). Dendritic transcripts are typically transported in a repressed state as components of large ribonucleoprotein complexes, and then translated upon stimulation at, or in the vicinity, of activated synapses. Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) is a trans-acting factor involved in dendritic mRNA trafficking, but how the distribution of the protein in dendrites is regulated has not been characterized. Here we found that a fraction of hnRNP A2/B1 is present at the synapse under resting conditions in cultured hippocampal neurons. Accordingly, this ribonucleoprotein was detected in free mRNP, monosomal, and polyribosomal fractions obtained from synaptoneurosomes. Neuronal activity and BDNF treatment increased hnRNP A2/B1 protein levels in the cell body and dendritic compartments, and induced the delivery of this protein to synaptic sites. The activitydependent accumulation of hnRNP A2/B1 at the synapse required, at least in part, the activation of TrkB receptors, presumably by BDNF. This neurotrophin also upregulated the hnRNP A2/B1 mRNA in the soma but was without effect on the abundance of neuritic hnRNP A2/B1 transcripts. These results show that the distribution of hnRNP A2/B1 is regulated by BDNF and by neuronal activity, an effect that may have a role in BDNF-induced synaptic plasticity events

    A Geometric Representation for the Proca Model

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    The Proca model is quantized in an open-path dependent representation that generalizes the Loop Representation of gauge theories. The starting point is a gauge invariant Lagrangian that reduces to the Proca Lagrangian when certain gauge is selected.Comment: 10 pages, Late

    Feno de pastagem nativa da "Zona de mimoso", como opcao para suplementacao do rebanho, na epoca seca.

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    Entre os diversos tipos de vegetacao do Piaui, a pastagem nativa da "zona de mimoso" e considerada uma das mais importantes do Estado. O maior problema enfrentado pelo pecuarista da regiao e a falta de forragempara o rebanho, na seca, ja que a pastagem cultivada e insignificante.Neste periodo a pastagem nativa seca totalmente e parte dela e carregada pelos ventos, tornando-se escassa a disponibilidade de forragem. Noperiodo chuvoso, a pastagem nativa chega a ser abundante e, as vezes excedendo o consumo animal. A producao de feno do excedente da pastagemnativa e uma opcao para suplementacao do gado na epoca critica. A UEPAE de Teresina produziu na "zona de mimoso" cerca de 9,0 t de feno parasuplementacao de seu rebanho. O trabalho foi realizado em marco de 1982, quando havia excedentes de forragem. Foram usados dois sistemas: 1)Todas as operacoes (roco, enleiramento e enfaradmento) forma executados manualmente. 2)Foi realizado roco mecanico, e enleiramento manual. Em ambos o enfardamento foi manual em prensa de feno. A maior producao de feno no sistema totalmente manual foi devido a altura de corte das plantas ter sido mais baixa. O feno produzido em Campo Maior tinha 7,85% de proteina bruta e 0,08% de fosforo, com base na materia seca. Este dados mostram que o teor de proteina e superior as necessidades de mantenca dos bovinos, que e de 7,0%. Quanto ao fosforo, esta abaixo de suas necessidades, precisando portanto, de suplementacao mineral.bitstream/item/95804/1/CT190001.pd
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