660 research outputs found
Computational fluids dynamics (CFD) in the spatial distribution of air velocity in prototype designed for animal experimentation in controlled environments
ArticleMaintaining a comfortable and productive thermal environment is one of the major
challenges of poultry farming in tropical and hot climates. The thermal environment encompasses
a number of factors that interact with each other and reflect the actual thermal sensation of the
animals. These factors characterize the microclimate inside the facilities and influence the
behaviour, performance and well-being of the birds. Thus, the objective of this study is to propose
and validate a computational model of fluid dynamics to evaluate the spatial distribution of air
velocity and the performance of a system designed to control air velocity variation for use in
experiments with birds in controlled environment. The performance of the experimental
ventilation prototype was evaluated based on air velocity distribution profiles in cages. Each
prototype consisted of two fans coupled to a PVC pipe 25 cm in diameter, one at each end of the
pipe, with airflow directed along the entire feeder installed in front of the cages. The contour
conditions considered for the simulation of airflow inside the cage were air temperature of 35 °C
at the entrance and exit of the cage; air velocity equal to 2.3 m s
-1
at the entrance of the cage;
pressure of 0 Pa. The model proposed in this study was representative when compared to the
experimental measurements, and it can be used in the study of air flow behaviour and distribution
for the improvement of the prototype design for later studies
Dissipative continuous Euler flows
We show the existence of continuous periodic solutions of the 3D
incompressible Euler equations which dissipate the total kinetic energy
Effect of the compound L-mimosine in an in vivo model of chronic granuloma formation induced by potassium permanganate (KMNO4).
The plant amino acid L-mimosine has recently been suggested to inhibit cells at a regulatory step in late G phase before establishment of active DNA replication forks. In addition, L-mimosine is an extremely effective inhibitor of DNA replication in chromosomes of mammalian nuclei. In this work, the effect of L-mimosine on chronic inflammation induced by dorsal injections of 0.2 ml of a 1:40 saturated crystal solution of potassium permanganate in mice, was studied. Seven days afterwards, all mice developed a subcutaneous granulomatous tissue indicative of chronic inflammatory response at the site of infection. The intraperitoneal administration of L-mimosine (200 μg/dose) to the potassium permanganate treated mice for 5 consecutive days (the first at the same time of inoculation of the KMnO4), produced a significant decrease in size and weight of the granuloma when compared to mice not treated with L-mimosine (controls). In addition, in all mice treated with L-mimosine, there was a strong inhibition of tumor necrosis factor alpha that was revealed in the serum (P<0.05) and in the minced granulomas. Interleukin-6 was not detected in the serum of treated and untreated mice. These findings show for the first time, that L-mimosine may have an anti-inflammatory effect on chronic inflammation and an inhibitory effect on tumor necrosis factor alpha and interleukin-6 generation in supernatant fluids of minced granulomas
The relative age effect on physical fitness in preschool children
The aim of the present study was to investigate the existence of a relative age effect (RAE) on physical fitness of preschoolers. Anthropometry and physical fitness were assessed in 3147 children (3–5 years old) using the PREFIT battery. Based on the birth year, participants were divided into 3year groups (3-, 4- and 5-years). Within each year group, 4quarter groups were created: quarter 1, preschoolers born from January to March; quarter 2, from April to June; quarter 3, from July to September; quarter 4, from October to December. The MANCOVA analysis revealed a main effect of year group (Wilks’ ¿ = 0.383; F10, 5996 = 369.64; p < 0.001, ¿p 2 = 0.381) and of quarter (Wilks’ ¿ = 0.874; F15, 8276.6 = 27.67; p < 0.001; ¿p 2 = 0.044) over the whole battery of tests. To the best of our knowledge, this is the first study to report the existence of RAE at the preschool stage. In general, performance improved as the relative age increased (i.e., those born in quarter 1 performed better than those in the other quarters). Individualization strategies should be addressed within the same academic year not only in elementary or secondary years but also in preschoolers
Whole exome sequence analysis reveals a homozygous mutation in PNPLA2 as the cause of severe dilated cardiomyopathy secondary to neutral lipid storage disease.
Accepted manuscript 12 month embargo, pre-print immediately
Limit cycles in uniform isochronous centers of discontinuous differential systems with four zones
We apply the averaging theory of first order for discontinuous differential systems to study the bifurcation of limit cycles from the periodic orbits of the uniform isochronous center of the differential systems ẋ = -y+x, y = x + xy, and ẋ = -y + xy, y = x + xy, when they are perturbed inside the class of all discontinuous quadratic and cubic polynomials differential systems with four zones separately by the axes of coordinates, respectively. Using averaging theory of first order the maximum number of limit cycles that we can obtain is twice the maximum number of limit cycles obtained in a previous work for discontinuous quadratic differential systems perturbing the same uniform isochronous quadratic center at origin perturbed with two zones separately by a straight line, and 5 more limit cycles than those achieved in a prior result for discontinuous cubic differential systems with the same uniform isochronous cubic center at the origin perturbed with two zones separately by a straight line. Comparing our results with those obtained perturbing the mentioned centers by the continuous quadratic and cubic differential systems we obtain 8 and 9 more limit cycles respectively
On twisted Fourier analysis and convergence of Fourier series on discrete groups
We study norm convergence and summability of Fourier series in the setting of
reduced twisted group -algebras of discrete groups. For amenable groups,
F{\o}lner nets give the key to Fej\'er summation. We show that Abel-Poisson
summation holds for a large class of groups, including e.g. all Coxeter groups
and all Gromov hyperbolic groups. As a tool in our presentation, we introduce
notions of polynomial and subexponential H-growth for countable groups w.r.t.
proper scale functions, usually chosen as length functions. These coincide with
the classical notions of growth in the case of amenable groups.Comment: 35 pages; abridged, revised and update
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