A Compact Gas Cerenkov Detector with Novel Optics

We discuss the design and performance of a threshold Cerenkov counter for identification of charged hadrons. The radiator is pressurized gas, which is contained in thin-walled cylindrical modules. A mirror system of novel design transports Cerenkov photons to photomultiplier tubes. This system is compact, contains relatively little material, and has a large fraction of active volume. A prototype of a module designed for the proposed CLEO III detector has been studied using cosmic rays. Results from these studies show good agreement with a detailed Monte Carlo simulation of the module and indicate that it should achieve separation of pions and kaons at the 2.5-3.0sigma level in the momentum range 0.8-2.8 GeV/c. We predict performance for specific physics analyses using a GEANT-based simulation package.Comment: Submitted to NIM. 23 pages, 11 postscript figures. Postscript file is also available at http://w4.lns.cornell.edu/public/CLNS/199

Informática para a terceira idade – características de um curso bem sucedido

The increase in life expectancy of humans brings new demands, particularly in the areas of health, in which actions must be planned to ensure a healthy elderly ageing. Among these are the actions that stimulate mental and social activities of the individual, slowing the degenerative processes of the mind and depression due to isolation. In this sense, computer courses have been of great importance to this age group, providing both benefits. However, activities geared to call elderly should be specific to it, so as to meet their needs without causing discomfort and/or feelings of failure. This article reports a study that is being developed in a course in basic computing for the elderly, offered at the Chemistry Institute at UNESP, Araraquara campus whose proposal is to focus in its planning and development, the peculiarities of the elderly. Therefore, the methodology adopted for the teaching-learning is different and the material is adequately prepared for the course.El aumento de la expectativa de vida de los seres humanos acarreta nuevas necesidades, especialmente en las áreas de salud, cuyas acciones deben estar previstas con el propósito de garantizar al anciano un envejecimiento saludable. Entre estas acciones estan las que estimulan las actividades mentales y sociales del individuo, retardando los procesos degenerativos y depresivos de la mente, que son resultados del aislamiento. En este sentido los cursos de imformática han sido de gran importancia para esa faja de edad,proporcionando benefícios en ambos lados de la actividad individual.Aún más, las actividades dirigidas especialmente para la tercera edad deben ser bastante específicas, visando atender a las necesidades, sin causar deconfort o sensación de incapacidad. Este articulo relata un trabajo desarrollado en un curso de informática Básica para la Tercera Edad, ofrecido por el Instituto de Química de la UNESP Campus de Araraquara, cuya propuesta visa en su plan el desarrollo peculiar del idoso. Asi, la metodología adoptada en el proceso de enseñanza -aprendizaje es diferenciada como también el material adecuado para el curso.O aumento da expectativa de vida dos seres humanos traz consigo novas demandas, especialmente nas áreas da saúde, na qual devem estar previstas ações no sentido de garantir ao idoso um envelhecimento saudável. Entre estas ações estão as que estimulam as atividades mentais e sociais do indivíduo, retardando os processos degenerativos e os depressivos da mente, resultantes do isolamento. Neste sentido, os cursos de informática têm sido de grande relevância para esta faixa etária, proporcionando benefícios aos dois âmbitos de atividade do indivíduo. Todavia, as atividades voltadas para a chamada terceira idade devem ser específicas para ela, de modo a atender às suas necessidades sem causar desconforto e/ou sensação de incapacidade. Este artigo relata um trabalho que vem sendo desenvolvido em um curso de Informática Básica para a Terceira Idade, oferecido no Instituto de Química da UNESP, campus de Araraquara, cuja proposta é focar, no seu planejamento e desenvolvimento, as peculiaridades do idoso. Assim, a metodologia adotada para o processo de ensino-aprendizagem é diferenciada e o material é adequadamente preparado para o curso

Evidence for the immobile bipolaron formation in the paramagnetic state of the magnetoresistive manganites

Recent research suggests that the charge carriers in the paramagnetic state of the magnetoresistive manganites are small polarons. Here we report studies of the oxygen-isotope effects on the intrinsic resistivity and thermoelectric power in several ferromagnetic manganites. The precise measurements of these isotope effects allow us to make a quantitative data analysis. Our results do not support a simple small-polaron model, but rather provide compelling evidence for the presence of small immobile bipolarons, i.e., pairs of small polarons. Since the bipolarons in the manganites are immobile, the present result alone appears not to give a positive support to the bipolaronic superconductivity theory for the copper-based perovskites.Comment: 6 pages, 5 figures, monor correction

Multi-phonon Raman scattering in semiconductor nanocrystals: importance of non-adiabatic transitions

Multi-phonon Raman scattering in semiconductor nanocrystals is treated taking into account both adiabatic and non-adiabatic phonon-assisted optical transitions. Because phonons of various symmetries are involved in scattering processes, there is a considerable enhancement of intensities of multi-phonon peaks in nanocrystal Raman spectra. Cases of strong and weak band mixing are considered in detail. In the first case, fundamental scattering takes place via internal electron-hole states and is participated by s- and d-phonons, while in the second case, when the intensity of the one-phonon Raman peak is strongly influenced by the interaction of an electron and of a hole with interface imperfections (e. g., with trapped charge), p-phonons are most active. Calculations of Raman scattering spectra for CdSe and PbS nanocrystals give a good quantitative agreement with recent experimental results.Comment: 16 pages, 2 figures, E-mail addresses: [email protected], [email protected], [email protected], accepted for publication in Physical Review

Electrophysiological Evidence of Atypical Spatial Attention in Those with a High Level of Self-reported Autistic Traits

Selective attention is atypical in individuals with autism spectrum conditions. Evidence suggests this is also the case for those with high levels of autistic traits. Here we investigated the neural basis of spatial attention in those with high and low levels of self-reported autistic traits via analysis of ERP deflections associated with covert attention, target selection and distractor suppression (the N2pc, NT and PD). Larger N2pc and smaller PD amplitude was observed in those with high levels of autistic traits. These data provide neural evidence for differences in spatial attention, specifically, reduced distractor suppression in those with high levels of autistic traits, and may provide insight into the experience of perceptual overload often reported by individuals on the autism spectrum

From thermal rectifiers to thermoelectric devices

We discuss thermal rectification and thermoelectric energy conversion from the perspective of nonequilibrium statistical mechanics and dynamical systems theory. After preliminary considerations on the dynamical foundations of the phenomenological Fourier law in classical and quantum mechanics, we illustrate ways to control the phononic heat flow and design thermal diodes. Finally, we consider the coupled transport of heat and charge and discuss several general mechanisms for optimizing the figure of merit of thermoelectric efficiency.Comment: 42 pages, 22 figures, review paper, to appear in the Springer Lecture Notes in Physics volume "Thermal transport in low dimensions: from statistical physics to nanoscale heat transfer" (S. Lepri ed.