605 research outputs found

    Wilson chains are not thermal reservoirs

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    Wilson chains, based on a logarithmic discretization of a continuous spectrum, are widely used to model an electronic (or bosonic) bath for Kondo spins and other quantum impurities within the numerical renormalization group method and other numerical approaches. In this short note we point out that Wilson chains can not serve as thermal reservoirs as their temperature changes by a number of order Delta E when a finite amount of energy Delta E is added. This proves that for a large class of non-equilibrium problems they cannot be used to predict the long-time behavior.Comment: 2 page

    An evaluation of the somatosensory profile of hemiparetic individuals

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    The purpose of this study was to evaluate the somatosensory profile of 18 hemiparetic spastic victims of stroke with and without blocking vision. Maximal isometric contraction test was used for flexor and extensor muscles of the hip and knee, and flexor plantar muscles. The number of cycles per minute on stationary bike was also measured with eyes opened and closed. Significant differences were found suggesting the existence of miscommunication between sensory-motor neural mechanisms responsible for voluntary motor actions in these individuals

    Perfil de ácidos grasos y comportamiento reológico de aceite y grasa de semillas de achiote (Bixa orellana), y de cacao blanco (Theobroma grandiflorum) y sus mezclas

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    Annatto seed oil (ASO) and cupuassu seed fat (CSF) were combined at the ratios: 30:70, 50:50, and 70:30 (% w/w). Their fatty acid profile, nutritional quality, FTIR (Fourier Transform Infrared) spectra, and rheological behavior were evaluated. ASO increased the content of polyunsaturated fatty acids in the blends; whereas CSF conferred higher contents of monounsaturated fatty acids. The blends exhibited low atherogenicity and thrombogenicity indices, suggesting nutritional advantages. The Newtonian fluid behavior and FTIR results suggested that mixing ASO and CSF at different proportions did not affect the functional groups. ASO showed an activation energy value which indicated that this fat viscosity was more sensitive to temperature changes. The Newtonian model proved to be suitable to describe the behavior of samples, according to statistical fit parameters R2, χ2, and RSS. The resulting blends presented improved physicochemical properties and nutritional attributes, indicating their feasibility for the development of new products.Se combinaron aceite de semilla de achiote (ASO) y grasa de semilla de cacao blanco (CSF) en las proporciones: 30:70, 50:50 y 70:30 (% p/p), respectivamente. Se evaluó su perfil de ácidos grasos, calidad nutricional, espectros FTIR (Fourier Transform Infrared) y comportamiento reológico. ASO incrementó el contenido de ácidos grasos poliinsaturados en las mezclas, mientras que CSF confirió mayores contenidos de ácidos grasos monoinsaturados. Las mezclas exhibieron bajos índices de aterogenicidad y trombogenicidad, lo que sugiere ventajas nutricionales. El comportamiento del fluido newtoniano y los resultados de FTIR sugirieron que mezclar ASO y CSF en diferentes proporciones no afectó a los grupos funcionales. ASO mostró un valor de energía de activación que indicó que la viscosidad de esta grasa era más sensible a los cambios de temperatura. El modelo newtoniano demostró ser adecuado para describir el comportamiento de las muestras, según los parámetros de ajuste estadístico R2, χ2 y RSS. Las mezclas resultantes presentaron propiedades fisicoquímicas y atributos nutricionales mejorados, lo que indica su viabilidad para el desarrollo de nuevos productos

    Three-dimensional CFD analysis of the hand and forearm in swimming

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    The purpose of this study was to analyze the hydrodynamic characteristics of a realistic model of an elite swimmer hand/forearm using three-dimensional computational fluid dynamics techniques. A three-dimensional domain was designed to simulate the fluid flow around a swimmer hand and forearm model in different orientations (0°, 45°, and 90° for the three axes Ox, Oy and Oz). The hand/forearm model was obtained through computerized tomography scans. Steady-state analyses were performed using the commercial code Fluent. The drag coefficient presented higher values than the lift coefficient for all model orientations. The drag coefficient of the hand/forearm model increased with the angle of attack, with the maximum value of the force coefficient corresponding to an angle of attack of 90°. The drag coefficient obtained the highest value at an orientation of the hand plane in which the model was directly perpendicular to the direction of the flow. An important contribution of the lift coefficient was observed at an angle of attack of 45°, which could have an important role in the overall propulsive force production of the hand and forearm in swimming phases, when the angle of attack is near 45°.Lif

    Swimming propulsion forces are enhanced by a small finger spread

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    The main aim of this study was to investigate the effect of finger spread on the propulsive force production in swimming using computational fluid dynamics. Computer tomography scans of an Olympic swimmer hand were conducted. This procedure involved three models of the hand with differing finger spreads: fingers closed together (no spread), fingers with a small (0.32 cm) spread, and fingers with large (0.64 cm) spread. Steady-state computational fluid dynamics analyses were performed using the Fluent code. The measured forces on the hand models were decomposed into drag and lift coefficients. For hand models, angles of attack of 0°, 15°, 30°, 45°, 60°, 75°, and 90°, with a sweep back angle of 0°, were used for the calculations. The results showed that the model with a small spread between fingers presented higher values of drag coefficient than did the models with fingers closed and fingers with a large spread. One can note that the drag coefficient presented the highest values for an attack angle of 90° in the three hand models. The lift coefficient resembled a sinusoidal curve across the attack angle. The values for the lift coefficient presented few differences among the three models, for a given attack angle. These results suggested that fingers slightly spread could allow the hand to create more propulsive force during swimming

    Modulation Of The Catalytic Activity Of Porphyrins By Lipid- And Surfactant-containing Nanostructures

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    The structural factors modulating porphyrin activity encompass pyrrole and equatorial ligands, as well as the central metal and the number and structure of their axial ligands. Of equal importance is the microenvironment provided by apoproteins, solvents and membranes. Porphyrins are often used to construct supramolecular structures with different applications. The modulation of activity of the porphyrins has been frequently achieved by mimicking nature, i.e., by the provision of different microenvironments for these molecules. The association of porphyrins to surfactant- and lipid-containing nanostructures has changed the activity of these compounds to mimic different enzymes such as SOD, cytochrome P450, peroxidases and others. In determined conditions, the reactive forms of the porphyrins are high-valence states of oxo-metal-π cations and oxo-metal produced by the reaction with peroxides and peracids. 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    LÍQUIDO FOLICULAR EQÜINO NA MATURAÇÃO IN VITRO DE OÓCITOS BOVINOS

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    O desenvolvimento embrionário de oócitos bovinos maturados in vitro (MIV) foi avaliado em meio suplementado com líquido folicular eqüino (Lfe). Foram distribuídos 1045 oócitos em 11 repetições formando três grupos tratamentos (T1, T2, T3) e um controle (C). O meio de maturação utilizado foi o TCM-199 acrescido de piruvato de sódio, hormônio folículo estimulante recombinante (rFSHh) e hormônio luteinizante equino (LHe). Suplementou-se esse meio com 10% de soro de égua em estro para o grupo controle e para T1, T2 e T3, o meio foi suplementado com 5, 10, e 20% de LFe, respectivamente. Os oócitos foram maturados in vitro (MIV) por 24h. A fecundação in vitro (FIV) foi realizada em meio Talp-Fert. A MIV e a FIV foram realizadas em estufa a 39ºC com 5% de CO2 em ar e umidade saturada. Os zigotos foram cultivados em meio SOFaaci, sob óleo mineral no interior de bolsas plásticas gaseificadas. As taxas de clivagem e de blastocistos foram observadas diariamente (D), e em D7, foram superiores (P0,05) às do grupo controle. Em D9, a taxa de blastocistos do T2 foi superior (P0,05). O LFe, na concentração de 10% pode ser utilizado, em substituição ao soro de égua em estro para suplementar o meio de MIV de oócitos bovinos. Equine follicular fluid on in vitro maturation of bovine oocytes Abstract Embryo development of bovine oocytes was evaluated using maturation medium supplemented with equine follicular fluid (eFF). One thousand and forty five (1045) oocytes were distributed in 11 replications forming three treatment groups (T1, T2 e T3) and one Control (C). TCM-199 added with sodium pyruvate, rFSHh and LHe was used as maturation medium. This medium was supplemented with 10% estrous mare serum for Control group, and 5, 10, and 20% eFF, respectively, for T1, T2 e T3 groups. In vitro maturation (IVM) of all groups was performed during 24h. In vitro fertilization (IVF) was performed in TALP-FERT medium. IVM and IVF were carried out in an incubator at 39ºC with 5% CO2 in air and saturated humidity. Zygotes were cultured in SOFaaci medium, under mineral oil in gasified bags. Cleavage and blastocyst rates were daily observed (D), and at D7, were higher (P0.05) for those from control group. At D9, blastocyst rate of T2 was higher (P0.05). The eFF, at a 10% concentration, can replace the use of estrous mare serum to supplement the IVM medium of bovine oocytes

    Renal tubular dysfunction in patients with American cutaneous leishmaniasis

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    Renal dysfunction seen in patients with American cutaneous leishmaniasis (ACL) has been attributed to the use of antimonials for treatment. To determine whether ACL itself causes tubular dysfunction, we measured renal function in 37 patients with ACL prior to their treatment and compared results to that in 10 healthy volunteers of similar mean age. None of the patients presented with glomerular dysfunction; however, 27 had a urinary concentrating defect. There was no statistical difference between groups in the pre- and post-desmopressin test of urine osmolality, but the post-test urine osmolality of the controls was significantly higher. Urinary AQP2 levels, determined by western blot of isolated exosomes, were found to be significantly lower in patients than in controls, whereas that of the cotransporter (NKCC2) was significantly higher. A urinary acidification defect (post-test pH greater than 5.50 following calcium chloride) was found in 15 patients. Pretest plasma bicarbonate was below normal in 12 patients as was the pretest plasma pH in 14. Expression of the Na/H exchanger (NHE3), H+-ATPase, and pendrin were all significantly higher in patients with ACL than in controls. A combined urinary concentration and acidification defect was found in 12 patients. Thus, the urinary concentrating defect of ACL may be caused by decreased AQP2, with increased NKCC2 compensatory. Pendrin upregulation may be related to the urinary acidification defect with increased NHE3 and H+-ATPase also compensatory. Hence, ACL can cause asymptomatic renal tubular dysfunction
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