Lattice specific heat for the RMIn5_5 (R = Gd, La, Y, M = Co, Rh) compounds: non-magnetic contribution subtraction

We analyze theoretically a common experimental process used to obtain the magnetic contribution to the specific heat of a given magnetic material. In the procedure, the specific heat of a non-magnetic analog is measured and used to subtract the non-magnetic contributions, which are generally dominated by the lattice degrees of freedom in a wide range of temperatures. We calculate the lattice contribution to the specific heat for the magnetic compounds GdMIn$_5$ (M = Co, Rh) and for the non-magnetic YMIn$_5$ and LaMIn$_5$ (M = Co, Rh), using density functional theory based methods. We find that the best non-magnetic analog for the subtraction depends on the magnetic material and on the range of temperatures. While the phonon specific heat contribution of YRhIn$_5$ is an excellent approximation to the one of GdCoIn$_5$ in the full temperature range, for GdRhIn$_5$ we find a better agreement with LaCoIn$_5$, in both cases, as a result of an optimum compensation effect between masses and volumes. We present measurements of the specific heat of the compounds GdMIn$_5$ (M = Co, Rh) up to room temperature where it surpasses the value expected from the Dulong-Petit law. We obtain a good agreement between theory and experiment when we include anharmonic effects in the calculations

Magnetic Field-Induced Condensation of Triplons in Han Purple Pigment BaCuSi2_2O6_6

Besides being an ancient pigment, BaCuSi$_2$O$_6$ is a quasi-2D magnetic insulator with a gapped spin dimer ground state. The application of strong magnetic fields closes this gap creating a gas of bosonic spin triplet excitations called triplons. The topology of the spin lattice makes BaCuSi$_2$O$_6$ an ideal candidate for studying the Bose-Einstein condensation of triplons as a function of the external magnetic field, which acts as a chemical potential. In agreement with quantum Monte Carlo numerical simulations, we observe a distinct lambda-anomaly in the specific heat together with a maximum in the magnetic susceptibility upon cooling down to liquid Helium temperatures.Comment: published on August 20, 200

Inspiratory resistance decreases limb blood flow in COPD patients with heart failure

Hosp Clin Porto Alegre, Exercise Pathophysiol Res Lab, BR-90035007 Porto Alegre, RS, BrazilHosp Clin Porto Alegre, Div Cardiol, BR-90035007 Porto Alegre, RS, BrazilSerra Gaucha Coll, Phys Therapy Dept, Caxias Do Sul, RS, BrazilHosp Clin Porto Alegre, Pulmonary Div, Porto Alegre, RS, BrazilFed Univ Rio Grande, Fac Med, Dept Med, Porto Alegre, RS, BrazilUniversidade Federal de São Paulo, Dept Med, Div Resp Dis, Pulmonary Funct & Clin Exercise Physiol Unit, São Paulo, BrazilQueens Univ, Dept Med, Div Respirol, LACEP, Kingston, ON, CanadaKingston Gen Hosp, Kingston, ON K7L 2V7, CanadaUniversidade Federal de São Paulo, Dept Med, Div Resp Dis, Pulmonary Funct & Clin Exercise Physiol Unit, São Paulo, BrazilWeb of Scienc

DISPOSITIVO PARA AUXILIAR ENSINO EM ENGENHARIA AEROESPACIAL

Due to the great number of theoretical classes in the Course of Aerospace Engineering of the University of Brasília at Gama, a distance exists between what is taught at the classroom and the practical application. The construction of a modular, reliable and low cost test bench dedicated to the exercise of theoretical knowledge apprehended in the classes of the course intends to present a possible solution to minimize this difficulty. Keywords: Test Device, Mobile Laboratory, Applied Teaching, Aerospace Engineering Education.Devido à grande quantidade de disciplinas teóricas disponíveis no Curso de Engenharia Aeroespacial da Faculdade do Gama, UnB, tem-se um distanciamento entre o que é ministrado na sala de aula com sua aplicação prática. A construção de um dispositivo de teste modular, confiável e de baixo custo dedicada ao exercício dos conhecimentos teóricos apreendidos nas disciplinas desse curso visa apresentar uma possível solução para minimizar essa dificuldade. Palavras-chave: Dispositivo de Testes, Laboratório Móvel, Ensino Aplicado, Educação em Engenharia Aeroespacial.  

Visual 3-D SLAM from UAVs

The aim of the paper is to present, test and discuss the implementation of Visual SLAM techniques to images taken from Unmanned Aerial Vehicles (UAVs) outdoors, in partially structured environments. Every issue of the whole process is discussed in order to obtain more accurate localization and mapping from UAVs flights. Firstly, the issues related to the visual features of objects in the scene, their distance to the UAV, and the related image acquisition system and their calibration are evaluated for improving the whole process. Other important, considered issues are related to the image processing techniques, such as interest point detection, the matching procedure and the scaling factor. The whole system has been tested using the COLIBRI mini UAV in partially structured environments. The results that have been obtained for localization, tested against the GPS information of the flights, show that Visual SLAM delivers reliable localization and mapping that makes it suitable for some outdoors applications when flying UAVs