Looking for intrinsic charm in the forward region at BNL RHIC and CERN LHC

The complete understanding of the basic constituents of hadrons and the hadronic dynamics at high energies are two of the main challenges for the theory of strong interactions. In particular, the existence of intrinsic heavy quark components in the hadron wave function must be confirmed (or disproved). In this paper we propose a new mechanism for the production of D-mesons at forward rapidities based on the Color Glass Condensate (CGC) formalism and demonstrate that the resulting transverse momentum spectra are strongly dependent on the behavior of the charm distribution at large Bjorken x. Our results show clearly that the hypothesis of intrinsic charm can be tested in pp and p(d)A collisions at RHIC and LHC. (C) 2010 Elsevier B.V. All rights reserved.

Driving forces for the adsorption of cyclopentene on InP(001)

In this work the interaction of cyclopentene with a set of InP(001) surfaces is investigated by means of the density functional theory. We propose a simple approach for evaluating the surface strain and based on it we have found a linear relation between bond and strain energies and the adsorption energy. Our results also indicate that the higher the bond energy, the more disperse the charge distribution is around the adsorption site associated to the high occupied state, a key feature that characterizes the adsorption process. Different adsorption coverages are used to evaluate the proposed equation. Our results suggest that the proposed approach might be extended to other systems where the interaction of the semiconductor surface and the molecule is restricted to first neighbor sites. (C) 2011 Elsevier B.V. All rights reserved.

Substitutional Impurities in PPV Crystals: An Intrinsic Donor-Acceptor System for High V(oc) Photovoltaic Devices

Defects are usually present in organic polymer films and are commonly invoked to explain the low efficiency obtained in organic-based optoelectronic devices. We propose that controlled insertion of substitutional impurities may, on the contrary, tune the optoelectronic properties of the underivatized organic material and, in the case studied here, maximize the efficiency of a solar cell. We investigate a specific oxygen-impurity substitution, the keto-defect -(CH(2)-C=O)- in underivatized crystalline poly(p-phenylenevinylene) (PPV), and its impact on the electronic structure of the bulk film, through a combined classical (force-field) and quantum mechanical (DFT) approach. We find defect states which suggest a spontaneous electron hole separation typical of a donor acceptor interface, optimal for photovoltaic devices. Furthermore, the inclusion of oxygen impurities does not introduce defect states in the gap and thus, contrary to standard donor-acceptor systems, should preserve the intrinsic high open circuit voltage (V(oc)) that may be extracted from PPV-based devices.

CALCULATION OF MAGNETODONOR STATES IN InP AND POLARON EFFECTS

Far-infrared transitions in polar semiconductors are known to be affected by the presence of shallow donor impurities, external magnetic fields and the electron-LO-phonon interaction. We calculate the magnetodonor states in indium phosphide by a diagonalization procedure, and introduce the electron-phonon interaction by the Frohlich term. The main effects of this perturbation are calculated by a multi-level version of the Wigner-Brillouin theory. We determine the transition energies, from the ground state to excited states, and find good qualitative agreement with recently reported absorption-spectroscopy measurements in the 100-800 cm(-1) range, with applied magnetic fields up to 30 T. Our calculations suggest that experimental peak splittings in the 400-450 cm(-1) range are due to the electron-phonon interaction.

Phase transition of demand explained by the heterogeneity of consumers' intrinsic preferences

In 1991 Gary S. Becker presented A Note on Restaurant Pricing and Other Examples of Social In uences on Price explaining why many successful restaurants, plays, sporting events, and other activities do not raise their prices even with persistent excess demand. The main reason for this is due to the discontinuity of stable demands, which is explained in Becker's (1991) analysis. In the present paper we construct a discrete time stochastic model of socially interacting consumers deciding for one of two establishments. With this model we show that the discontinuity of stable demands, proposed by Gary S. Becker, depends crucially on an additional factor: the dispersion of the consumers' intrinsic preferences for the establishments.

Intrinsic and relational perspectives of relationship value: an integrated framework in buyer-supplier relationships

O relacionamento entre firmas vem sendo estudado como um fator que amplia os limites do valor criado pelas firmas individualmente, por meio da construção conjunta de benefícios que não poderia ocorrer caso o relacionamento não se estabelecesse. O valor total criado no nível da díade, que é capturado pelas partes, é o valor do relacionamento. Os benefícios obtidos transcendem as características financeiras da transação, podendo converter-se em outros aspectos da relação entre as firmas, tais como capacitação técnica, oferta de serviços, capacidade de inovação e reputação. Os recursos compartilhados e trocados entre as partes são fontes de criação de valor no relacionamento, mas originam-se de duas perspectivas diferentes. Eles podem pertencer previamente a uma delas, compondo um valor que é intrínseco, ou desenvolverem-se ao longo do relacionamento em si, resultando numa parcela de valor relacional. Neste contexto, este estudo propõe-se a investigar as diferentes características das partes que são fonte de criação de valor em um relacionamento, bem como analisar os aspectos que influenciam sua captura pelas partes. O estudo envolveu três etapas. A primeira, de cunho teórico, visou a explorar as dimensões do valor do relacionamento, no que se refere à sua definição e suas fontes. As duas etapas seguintes objetivaram testar empiricamente o efeito das fontes do valor do relacionamento na criação e captura de valor, por meio de uma survey transversal e um estudo de casos múltiplos. A perspectiva teórica que permeia o estudo é a Visão Baseada em Recursos, uma vez que ela pressupõe que os recursos das firmas produzem valor econômico que transcende os limites delas e é capturado por seus clientes e fornecedores. A abordagem ontológica é a do realismo crítico, a qual permite um melhor entendimento dos acontecimentos empiricamente observados. Os resultados contribuem para um melhor entendimento teórico sobre valor do relacionamento, uma vez que os construtos de valor intrínseco e valor relacional integram diferentes fontes de benefícios que podem advir de relacionamentos. A relação entre esses construtos e sua influência individual na captura de valor também trazem uma contribuição teórica ao estudo de relacionamentos comprador-fornecedor. As principais contribuições gerenciais dizem respeito ao fato de que é possível capturar valor mesmo que o relacionamento não seja colaborativo. Adicionalmente, os resultados enfatizam que as empresas deveriam explorar mais como fazer para extrair mais benefícios da outra parte e do relacionamento em si, em especial de fontes não-financeiras.

Efficiency of extrinsic and intrinsic charge-carrier photogeneration processes obtained from the steady-state photocurrent action spectra of poly(p-phenylene vinylene) derivatives

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Intrinsic flavor violation for massive neutrinos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sulfation of intrinsic glycoproteins of the rabbit vitreous

The experiments reported here were designed to characterize the intrinsic vitreous glycoproteins and to understand the process of their sulfation. Rabbits were injected intravitreally with S-35-sodium sulfate and killed at several time intervals after injection. In another series of experiments, rabbits were injected either with S-35-sodium sulfate, H-3-fucose or H-3-tyrosine, associated or not associated with tunicamycin administration. Vitreous from the control eyes was also digested with N-glycosidase.. Furthermore, ciliary bodies, the putative source of the intrinsic vitreous glycoproteins, were incubated with S-35-sodium sulfate in the presence or absence of the protein synthesis inhibitor cycloheximide, and the culture media recovered for analysis. These and the vitreous samples of the other experiments were processed for sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fluorography. Except for serum albumin, practically all polypeptide bands of the vitreous and culture media were labeled with radioactive sulfate and were shown to undergo renewal. The experiments using tunicamycin or enzyme treatment suggest that radioactive sulfate was incorporated not only into the carbohydrate side chains of the glycoproteins but also into the amino acid tyrosine of the polypeptide backbone of these glycoproteins. (C) 1998 Academic Press.

CALCULATION of MAGNETODONOR STATES IN InP and POLARON EFFECTS

Far-infrared transitions in polar semiconductors are known to be affected by the presence of shallow donor impurities, external magnetic fields and the electron-LO-phonon interaction. We calculate the magnetodonor states in indium phosphide by a diagonalization procedure, and introduce the electron-phonon interaction by the Frohlich term. The main effects of this perturbation are calculated by a multi-level version of the Wigner-Brillouin theory. We determine the transition energies, from the ground state to excited states, and find good qualitative agreement with recently reported absorption-spectroscopy measurements in the 100-800 cm(-1) range, with applied magnetic fields up to 30 T. Our calculations suggest that experimental peak splittings in the 400-450 cm(-1) range are due to the electron-phonon interaction.

Intrinsic and extrinsic factors in the conservation of ants and their use as bioindicators.

Ant communities are sensitive to fragmentation responding through: extinction of specialist species compared with large habitats, invasion of generalist species, changes in community composition and richness of species. Because of these characteristics, this review aims at examining the main risks that ants have been facing to maintain their communities, as well as to report current conservation practices in Brazil and in the world.

Nucleation and growth evolution of InP dots on InGaP/GaAs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Vertical and in-plane electrical transport in InAs/InP semiconductor nanostructures

Vertical and in-plane electrical transport in InAs/InP semiconductors wires and dots have been investigated by conductive atomic force microscopy (C-AFM) and electrical measurements in processed devices. Localized I-V spectroscopy and spatially resolved current images (at constant bias), carried out using C-AFM in a controlled atmosphere at room temperature, show different conductances and threshold voltages for current onset on the two types of nanostructures. The processed devices were used in order to access the in-plane conductance of an assembly with a reduced number of nanostructures. On these devices, signature of two-level random telegraph noise (RTN) in the current behavior with time at constant bias is observed. These levels for electrical current can be associated to electrons removed from the wetting layer and trapped in dots and/or wires. A crossover from conduction through the continuum, associated to the wetting layer, to hopping within the nanostructures is observed with increasing temperature. This transport regime transition is confirmed by a temperature-voltage phase diagram. © 2005 Materials Research Society.

Electrical properties of individual and small ensembles of InAs/InP nanostructures

We investigate electrical properties of InAs/InP semiconductor nanostructures by conductive atomic force microscopy (C-AFM) and current measurements at low temperatures in processed devices. Different conductances and threshold voltages for current onset were observed for each type of nanostructure. In particular, the extremity of the wire could be compared to a dot with similar dimensions. The processed devices were used in order to access the in-plane conductance of an assembly of a reduced number of nanostructures. Here, fluctuations on I-V curves at low temperatures (<40 K) were observed. At these low temperatures and for a suitable range of applied voltages, random telegraph noise (RTN) in the current was observed for devices with dots. These fluctuations can be associated to electrons trapped in dots, as suggested by numerical simulations. A crossover from a semiconductor-like to a metallic transport behavior is also observed for similar parameters. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.