Convective instabilities in two superposed horizontal liquid layers heated laterally

This work is devoted to the theoretical study of the stability of two superposed horizontal liquid layers bounded by two solid planes and subjected to a horizontal temperature gradient. The liquids are supposed to be immiscible with a nondeformable interface. The forces acting on the system are buoyancy and interfacial tension. Four different flow patterns and temperature profiles are found for the basic state. A linear perturbative analysis with respect to two and three dimensional perturbations reveals the existence of three kind of patterns. Depending on the relative height of both liquids several situations are predicted: either wave propagation from cold to the hot regions, or waves propagating in the opposite direction or still stationary longitudinal rolls. The behavior of three different pairs of liquids which have been used in experiments on bilayers under vertical gradient by other authors have been examined. The instability mechanisms are discussed and a qualitative interpretation of the different behaviors exhibited by the system is provided. In some configurations it is possible to find a codimension-two point created by the interaction of two Hopf modes with different frequencies and wavenumbers. These results suggest to consider two liquid layers as an interesting prototype for the study of propagation and interaction of waves in the context of the B\'enard-Marangoni problem.Comment: 21 pages, 9 figures, 2 tables;accepted to be published in PR

Jumping-based asymmetries are negatively associated with jump, change of direction, and repeated sprint performance, but not linear speed, in adolescent handball athletes

The aim of the present study was to determine the association of multi-directional jumping asymmetries with measures of physical performance. Forty-two youth handball athletes (age: 16.0 ± 1.3 years; body height: 174.11 ± 7.3 cm; body mass: 70.49 ± 13.3 kg) performed a mid-season fitness test battery consisting of single leg countermovement, lateral and broad jump tests, two change of direction speed (CODS) tests, an 8 x 10 m repeated sprint test, and a 20 m sprint. The Kappa coefficient showed only ‘slight’ levels of agreement (K range = -0.05 to 0.15), indicating that asymmetries rarely favoured the same side during each of the jump tests. The single leg countermovement jump showed significantly (p = 0.006) larger asymmetries (11.2 ± 8.4) than the broad jump (6.4 ± 4.6) and significant correlations were present between jumping asymmetries and jump (r = -0.32 to -0.52), CODS (r = 0.31 to 0.32) and repeated sprint (r = 0.35 to 0.40) performance. The findings of the present study highlight the independent nature of jumping asymmetries and associations with measures of physical performance. Practitioners are encouraged to use multiple tests to detect existing side differences and consider appropriate training interventions for the reduction of inter-limb asymmetries

Avaliacao clinico-laboratorial de bovinos Nelores infectados experimentalmente com Trypanosoma vivax.

bitstream/item/137703/1/PESQ-EM-ANDAMENTO-51.pdfCNPGC

Desenvolvimento de uma prova de imunoadsorcao enzimática para detecção de anticorpos contra Trypanosoma vivax em bovinos: resultados preliminares.

bitstream/item/137691/1/PESQ-EM-ANDAMENTO-50.pdfCNPGC