Transport simulations in hierarchically disordered nanostructures for thermoelectric material design

Hierarchically nanostructured materials, where disorder is introduced in various length scales (at the atomic scale, the nanoscale, and the mesoscale) is one of the most promising directions to achieve extremely low thermal conductivities and improve thermoelectric performance. Here we theoretically investigate one such system, a nanocrystalline material with nanopores that are introduced between the crystalline regions. We use the Nonequilibrium Greens Function method for electronic transport and Molecular Dynamics for phonon transport.Comment: 4 pages, 2 figure

Heat current anticorrelation effects leading to thermal conductivity reduction in nanoporous Si

Prevailing nanostructuring strategies focus on increasing phonon scattering and reducing the mean-free-path of phonons across the spectrum. In nanoporous Si materials, for example, boundary scattering reduces thermal conductivity drastically. In this work, we identify an unusual anticorrelated specular phonon scattering effect which can result in additional reductions in thermal conductivity of up to ∼80% for specific nanoporous geometries. We further find evidence that this effect has its origin in heat trapping between large pores with narrow necks. As the heat becomes trapped between the pores, phonons undergo multiple specular reflections such that their contribution to the thermal conductivity is partly undone. We find this effect to be wave-vector dependent at low temperatures. We use large-scale molecular-dynamics simulations, wave-packet analysis, as well as an analytical model to illustrate the anticorrelation effect, evaluate its impact on thermal conductivity, and detail how it can be controlled to manipulate phonon transport in nanoporous materials

O regime da clemência no direito da concorrência

Os cartéis assumem uma das formas mais gravosas das práticas anti concorrenciais atendendo à subversão do normal funcionamento do mercado e dos danos daí resultantes, quer para os consumidores, quer para os concorrentes das empresas que integram estas organizações. O secretismo que caracteriza a formação e o funcionamento organizacional dos cartéis torna-os praticamente indetetáveis, pelo que a investigação por iniciativa das autoridades da concorrência é insuficiente para o seu desmantelamento. É neste contexto que surgem os programas de clemência, enquanto forma de deteção destas práticas restritivas horizontais, que são promovidos pelas autoridades dos diversos Estados que adotaram este mecanismo legal. Com o presente trabalho pretende-se proceder à análise do regime da clemência, quer no contexto europeu, quer no nacional, nomeadamente no que se refere às condições de concessão deste programa e aos benefícios que as empresas colaborantes podem obter caso denunciem o cartel que integram. Da mesma forma pretende-se analisar a sua eficácia questionando-se se será o único meio de combate a estes acordos horizontais ou se, porventura, medidas como a criminalização e o agravamento das coimas aplicáveis coadjuvarão no cumprimento das regras da concorrência. Questiona-se a motivação do recurso a este instituto, bem sabendo que a partir do momento em que se torne pública a decisão no processo investigatório dos cartéis, as empresas ficam sujeitas a que os lesados pela atividade cartelista possam vir deduzir ações de responsabilidade civil contra todos os membros dos cartéis, com vista ao ressarcimento dos danos daí resultantes. Referimo-nos ao denominado private enforcement e à sua articulação com o regime da clemência, no sentido de apurar se é possível a sua coexistência sem que, por um lado, se desvirtue o regime da clemência e as empresas sejam compelidas a denunciar e, por outro, sem que os lesados deixem de exercer os seus direitos.Cartels activities assume one of the most damaging anticompetitive practices in the market regular running. It inflicts serious impairments on the consumers as well as on the corporations that compete with those integrating the cartels. The distinctive secrecy cloak around the cartels establishment and operation are nearly untraceable. Thus, investigation led by the proper competition law authorities is still insufficient in order to fully dismantle cartels. Within these circumstances, leniency policies emerge as legal mechanisms for detection and examination of such horizontal agreements, being promoted in several countries. In this present work, the leniency regimes within the national and European contexts are analysed, particularly in terms of the requirements and benefits offered to the applying companies. Equally, the effectiveness of leniency policies is thoroughly probed in this dissertation, rising and addressing further questions. For example, if leniency regimes are the only possible means of contesting the horizontal agreements, or if additional criminal actions concerted with substantial increase of the penalties would be more successful in protecting and defending the competition law. The motivation behind the application of companies to take advantage from the leniency policy is also questioned in this work. A stand-alone action, or an action that follows on a public enforcement decision, may activate private enforcement which, in its turn, is a litigation on the establishment of an antitrust infringement. Then, imposition of injunctive reliefs and recovery of the damages suffered may be decided by the court. Consequently, the co-existence between private enforcement and the leniency policy is explored since it is equally important that companies provide intel but all those penalised by antitrust enforcement can exercise their rights

Description of the larva and pupa of Apion brevicorne Gerstaecker, 1854 (Coleoptera: Brentidae: Apioninae) with biological information

Apion brevicorne Gerstaecker, 1854 (Coleoptera: Brentidae: Apioninae) is an ecologically and economically important weevil that feeds on seeds and tissues of trees in the genus Copaifera L. (Fabaceae). Although the genus Apion comprises 16 species restricted to the Paleartic region, the Neotropical species A. brevicorne is still considered as incertae sedis due to the absence of a systematic study about it. The first descriptions and illustrations of Apion brevicorne are provided here. Diagnostic characters of larva and pupa are included and compared with 13 species from other biogeographic regions. Details of immature Apioninae species associated with host plants from the Neotropical region are described for the first time

Profile of patients diagnosed with AIDS at age 60 and above in Brazil, from 1980 until June 2009, compared to those diagnosed at age 18 to 59.

OBJECTIVES: The aim of this study was to learn more about people diagnosed with acquired immunodeficiency syndrome (AIDS) at age 60 and above in Brazil, and to compare them with people diagnosed at a younger age. METHODS: This study was based on the analysis of secondary data from the Brazilian AIDS Program. The study population consisted of people diagnosed with AIDS at age 60 and above. The comparison group was comprised of a 20% random sample of people diagnosed at age 18 to 59, frequency-matched by year of diagnosis. RESULTS: 544,846 cases of AIDS were reported in Brazil from 1980 until June 2009. Over 90% of cases were diagnosed between 18 and 59 years of age, and 13,657 (2.5%) at age 60 and above. The first case of AIDS among the elderly was reported in 1984. The comparison group consisted of 101,528 patients. Gender proportion was similar for both groups, and the proportion of people identified with AIDS after death in the Brazilian Mortality Information System (SIM) was 4% higher among the elderly. Both groups were also similar regarding the region of residence; a markedly higher proportion lived in Southeastern Brazil. Older people were more likely to have lower education and to have contracted AIDS by heterosexual contact, and less likely to be intravenous drug users. Male to female ratio among those diagnosed with AIDS at or above age 60 decreased over the years, in the same way as observed for the whole cohort. Mortality was higher among men in both groups. CD4 category (taken closest to the date of AIDS diagnosis) was very similar in both groups. CONCLUSION: The characteristics of the epidemic among the elderly show similarities to the younger group considering gender distribution and CD4 category, but differ regarding educational level and exposure category. Also, the elderly were more likely not to have their AIDS condition promptly diagnosed

Aplicação multimédia sobre a Ria Formosa e seus fins educacionais (ForDid)

Na atualidade torna-se inquestionável a necessidade de integrar a aprendizagem com as novas tecnologias de modo a cativar e facilitar a compreensão dos temas abordados através de aplicações didáticas. Durante a última década o Centro de Investigação Marinha e Ambiental (CIMA) assumiu a responsabilidade de criar meios eficazes de comunicação entre o público em geral e a comunidade científica, através de plataformas multimédia interativas. Foram objecto destas aplicações didáticas as várias vertentes do património natural do Algarve. Após o sucesso das primeiras aplicações GuaDid e MonDid visando o Estuário do Rio Guadiana e a Serra de Monchique respectivamente, o desafio de criar e inovar foi acrescido, resultando numa nova aplicação – ForDid, visando a divulgação do importante sistema lagunar Ria Formosa.info:eu-repo/semantics/publishedVersio

Holocene history of Ria Formosa coastal lagoon system (Southern Portugal): borehole evidence and threedimensional paleotopography

A paleotopographic model of Ria Formosa is presented based on two borehole campaigns and a systematic comparison with previous works, revealing the existence of a complex network of fluvial valleys. Vertical sediment profiles showed a mosaic of changing depositional environments, resulting from local hydrodynamics, sedimentary sources and, to an extent, by the structurally inherited accommodation space. Sedimentological, geochemical and micropaleontological data were put in the context of an age model obtained from 14C datings, pointing to the existence of an estuarine environment subjected to a rapid coastal flooding from ca. 10000 to 7500 cal. years B.P., followed by a period of infilling in an increasingly confined coastal lagoon environment.info:eu-repo/semantics/publishedVersio

Effect of wave versus particle phonon nature in thermal transport through nanostructures

Comprehensive understanding of thermal transport in nanostructured materials needs large scale simulations bridging length scales dictated by different physics related to the wave versus particle nature of phonons. Yet, available computational approaches implicitly treat phonons as either just waves or as particles. In this work, using a full wave-based Non-Equilibrium Green's Function (NEGF) method, and a particle-based ray-tracing Monte Carlo (MC) approach, we investigate the qualitative differences in the wave and particle-based phonon transport at the vicinity of nanoscale features. For the simple example of a nanoporous geometry, we show that phonon transmission agrees very well for both methods with an error margin of ±15%, across phonon wavelengths even for features with sizes down to 3–4 nm. For cases where phonons need to squeeze in smaller regions to propagate, we find that MC underestimates the transmission of long wavelength phonons whereas wave treatment within NEGF indicates that those long wavelength phonons can propagate more easily. We also find that particle-based simulation methods are somewhat more sensitive to structural variations compared to the wave-based NEGF method. The insight extracted from comparing wave and particle methods can be used to provide a better and more complete understanding of phonon transport in nanomaterials