228 research outputs found

    Distinct neuron phenotypes may serve object feature sensing in the electrosensory lobe of Gymnotus omarorum

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    Early sensory relay circuits in the vertebrate medulla often adopt a cerebellum-like organization specialized for comparing primary afferent inputs with central expectations. These circuits usually have a dual output, carried by center ON and center OFF neurons responding in opposite waysto the samestimulus at the center of their receptive fields. Here, we show in the electrosensory lateral line lobe of Gymnotiform weakly electric fish that basilar pyramidal neurons, representing ‘ON’ cells, and non-basilar pyramidal neurons, representing ‘OFF’ cells, have different intrinsic electrophysiological properties. We used classical anatomical techniques and electrophysiological in vitro recordings to compare these neurons. Basilar neurons are silent at rest, have a high threshold to intracellular stimulation, delayed responses to steady-state depolarization and low pass responsiveness to membrane voltage variations. They respond to low-intensity depolarizing stimuli with large, isolated spikes. As stimulus intensity increases, the spikes are followed by a depolarizing after-potential from which phase-locked spikes often arise. Non-basilar neurons show a pacemaker-like spiking activity, smoothly modulated in frequency by slow variations of stimulus intensity. Spike-frequency adaptation provides a memory of their recent firing, facilitating non-basilar response to stimulus transients. Considering anatomical and functional dimensions, we conclude that basilar and non-basilar pyramidal neurons are clear-cut, different anatomo-functional phenotypes. We propose that, in addition to their role in contrast processing, basilar pyramidal neurons encode sustained global stimuli such asthose elicited by large or distant objects while nonbasilar pyramidal neurons respond to transient stimuli due to movement of objects with a textured surface.Agencia Nacional de Investigación e Innovació

    Quantitative image of fluorescence of ceramic and resin-cement veneers

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    The main of the study was quantify the effect of two ceramics with two underlying resin cements on apparent fluorescence levels. Buccal surfaces of two bovine incisors were ground flat producing one enamel and one dentin substrate. The veneers were fabricated (0.5 and 1.0 mm thickness) using two ceramics (IPSe. max Press and IPSe. max Zirpress, Ivoclar Vivadent). Veneers were cemented using either light-cured (Variolink II, Ivoclar Vivadent) or self-adhesive dual (Rely X U200, 3M ESPE) cement. The layered Control group materials had no cement application. Semi-quantitative fluorescence image analysis (Matlabs software, Matworks) involved processing the images as captured under each daylight (DL, Gretagmacbeth) and ultraviolet illuminants (UVA, Sylvania) within a neutral-gray lightbox (Macbeth Spectral Light). Statistical analysis of the quantitative fluorescence values was performed using two-way ANOVA and Tukey's test (p < 0.05). The e. max Zirpress on the dentin substrate produced greater fluorescence (p < 0.05) when subjected to UV illumination and more fluorescence (p < 0.05) than e. max Press in both cement groups. Light-cured cement produced higher (p < 0.05) fluorescence than the dual-cement with e. max Press on enamel under UV illumination. The fluorescence for e. max Press on the dentin substrate was greater (p < 0.05) than for e. max Zirpress using dual self-adhesive cement subjected to daylight illumination. Thus, it is possible to conclude that the combination of ceramic and cement produce definite, significant effects on the apparent fluorescence, vital quality for restorative dentistry3

    Reduction of blood nitric oxide levels is associated with clinical improvement of the chronic pelvic pain related to endometriosis

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    The objective of this prospective study was to determine the plasma levels of nitric oxide (NO) in women with chronic pelvic pain secondary to endometriosis (n=24) and abdominal myofascial pain syndrome (n=16). NO levels were measured in plasma collected before and 1 month after treatment. Pretreatment NO levels (μM) were lower in healthy volunteers (47.0±12.7) than in women with myofascial pain (64.2±5.0, P=0.01) or endometriosis (99.5±12.9, P<0.0001). After treatment, plasma NO levels were reduced only in the endometriosis group (99.5±12.9 vs 61.6±5.9, P=0.002). A correlation between reduction of pain intensity and reduction of NO level was observed in the endometriosis group [correlation = 0.67 (95%CI = 0.35 to 0.85), P<0.0001]. Reduction of NO levels was associated with an increase of pain threshold in this group [correlation = -0.53 (-0.78 to -0.14), P<0.0001]. NO levels appeared elevated in women with chronic pelvic pain diagnosed as secondary to endometriosis, and were directly associated with reduction in pain intensity and increase in pain threshold after treatment. Further studies are needed to investigate the role of NO in the pathophysiology of pain in women with endometriosis and its eventual association with central sensitization.484363369CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQSem informaçã

    Towards NNLO Accuracy in the QCD Sum Rule for the Kaon Distribution Amplitude

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    We calculate the O(αs)O(\alpha_s) and O(αs2)O(\alpha_s^2) gluon radiative corrections to the QCD sum rule for the first Gegenbauer moment a1Ka_1^K of the kaon light-cone distribution amplitude. The NNL0 accuracy is achieved for the perturbative term and quark-condensate contributions to the sum rule. A complete factorization is implemented, removing logarithms of ss-quark mass from the coefficients in the operator-product expansion. The sum rule with radiative corrections yields a_1^K(1 \GeV)=0.10\pm 0.04.Comment: 14 pages, 2 figure

    The 16th moment of the three loop anomalous dimension of the non-singlet transversity operator in QCD

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    We present the result of the three loop anomalous dimension of non-singlet transversity operator in QCD for the Mellin moment N=16. The obtained result coincides with the prediction from arXiv:1203.1022 and can serve as a confirmation of the correctness of the general expression for three loop anomalous dimension of non-singlet transversity operator in QCD for the arbitrary Mellin moment.Comment: 7 pages, 1 figure, minor changes in the tex

    Supersymmetric Extension of the Lorentz and CPT-Violating Maxwell-Chern-Simons Model

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    Focusing on gauge degrees of freedom specified by a 1+3 dimensions model hosting a Maxwell term plus a Lorentz and CPT non-invariant Chern-Simons-like contribution, we obtain a minimal extension of such a system to a supersymmetric environment. We comment on resulting peculiar self-couplings for the gauge sector, as well as on background contribution for gaugino masses. Furthermore, a non-polynomial generalization is presented.Comment: revtex4, 4 pages, no figure

    Incidência de ferrugem em folhas de pessegueiro e nectarineira do germoplasma IAC

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    The occurrence of rust leaf disease (Tranzschelia discolor f. sp domesticae) was verified in 24 peach and nectarine selections at the Jundiaí Experimental Station (23&deg;08'S and 46&deg;55'W) State of São Paulo, Brazil. The trees of the germoplasm bank were evaluated using a sympton scale to evaluate selection susceptibility to the pathogen, at different levels. The less susceptible selections were: 1) peaches 'Regis' and IAC 4685-45 and 2) nectarines 'Josefina' and IAC N 2680-91.Avaliou-se, em fins do verão de 1993, o grau de incidência da ferrugem (Tranzschelia discolor f. sp. domesticae), em dezoito seleções IAC de pessegueiro e seis de nectarineira, mantidos em lote de germoplasma na Estação Experimental de Jundiaí (23&deg;08'S; 46&deg;55'W). A porcentagem de incidência do patógeno foi estimada através de observações macroscópicas das folhas, atribuindo-se notas de 1 a 5 (1 = nula, 2 = leve, 3 = moderada, 4 = severa, 5 = muito severa), conforme o grau da severidade do sintoma. Todo o material pesquisado mostrou-se suceptível ao patógeno, entretanto, as seleções apresentaram sensíveis variações em graus de susceptibilidade. As seleções com maior tolerância ao patógeno foram: 1) pêssegos 'Régis' e IAC 4685-45 e 2) nectarinas 'Josefina' e IAC N 2680-91

    Anomalous dimensions and phase transitions in superconductors

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    The anomalous scaling in the Ginzburg-Landau model for the superconducting phase transition is studied. It is argued that the negative sign of the η\eta exponent is a consequence of a special singular behavior in momentum space. The negative sign of η\eta comes from the divergence of the critical correlation function at finite distances. This behavior implies the existence of a Lifshitz point in the phase diagram. The anomalous scaling of the vector potential is also discussed. It is shown that the anomalous dimension of the vector potential ηA=4d\eta_A=4-d has important consequences for the critical dynamics in superconductors. The frequency-dependent conductivity is shown to obey the scaling σ(ω)ξz2\sigma(\omega)\sim\xi^{z-2}. The prediction z3.7z\approx 3.7 is obtained from existing Monte Carlo data.Comment: RevTex, 20 pages, no figures; small changes; version accepted in PR

    Economic analysis of an agrosilvipastoral system for a mountainous area in Zona da Mata Mineira, Brazil

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    The objective of this work was to evaluate the economic viability of an agrosilvipastoral system developed for Zona da Mata mountainous areas in Minas Gerais state, Brazil, as well as to compare different options for wood (Eucalyptus grandis and Acacia mangium) commercialization of the second thinning. The data were obtained from a 10 year-old agrosilvipastoral system established in four hectares at Embrapa Gado de Leite station in Coronel Pacheco, MG, Brazil. As evaluation criteria for the economic viability analysis, the adopted methods were the net present value (NPV) and the internal rate of return (IRR), both calculated at 6% interest rate. Despite the small difference, adding value to forest products increased the attractiveness of the proposed system. Considered separately, the agricultural activity was impracticable, whereas the forestry and livestock activities were independently viable. The studied system seems to be equally tolerant to price variations for forest and livestock products, as well as strongly tolerant to variations in production costs
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