Quantum chemical modeling of perovskite: An investigation of piezoelectricity in ferrite of yttrium

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Notes on beta-deformations of the pure spinor superstring in AdS(5) x S-5

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

Oscillating holograms recorded in photorefractive crystals by a frequency detuned feedback loop

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

Tosse, uma visão do otorrinolaringologista.

Persistent cough leads individuals to seek for medical assistance. Clinical investigation, however, may not reveal any alteration within the clinic's sphere of action. Often enough, some professionals treat the symptom as a disease, introducing several medicines, unsuccessfully. The author's experience, as an otolaryngologist, allows to state that many of these professionals ignore the upper aerodigestive tract as a cough-generator site. The present work discusses the alterations on the mentioned tract, which may provoke the cough reflex, reviewing, initially, the cough mechanism and the localization of the specific receptors. Cough is produce by stimulus at the receptor level or far from it. In upper and lower parts of the aerodigestive tract secretions may run to several directions. Secretion from the paranasal sinus is a frequent cause of cough. Acute sinusitis may occur insidiously bringing about the chronification of the inflammation with cough being the only great apparent symptom. Nasal and dental alterations favor sinusal infection. Signs and symptoms, even if minimum, may be detected through an accurate anamnesis. Nasal allergy, laryngitis, post nasal dripping and septal deviation may also produce cough. The ORL examination is, therefore, imperative, and no radiologic examination can substitute for it. An inadequate treatment, particularly of the sinusitis, may bring about a worsening and extension of the initial condition.

Cogeneration for small users: case studies for Brazilian tertiary sector

In this paper we present technical and economic studies of cogeneration systems utilizing combustion engines and gas turbines, applied in two establishments of the tertiary sector, regarding Brazilian conditions (according to Silveria, 1994). In the first step cogeneration systems utilizing combustion engines associated to absorption refrigeration systems are studied, in which electricity and cold air for a university building rate produced. In the second step some possibilities of the use of the gas turbine in cogeneration systems for a hospital are shown. In this case, the exhaust gases are utilized for the production of steam in a heat recovery steam generator (HRSG) or cold water in an absorption refrigeration system (for air conditioning) for the hospital building. The dynamic increment of the energy demand of Brazilian tertiary sector in last years can increase the installation of these cogeneration system (in compact version) as well as strengthen the development of the decentralized energy generation in Brazil.

Special subsets and optimum codes based on lattices and cosets

This paper introduces the concept of special subsets when applied to generator matrices based on lattices and cosets as presented by Calder-bank and Sloane. By using the special subsets we propose a non exhaustive code search for optimum codes. Although non exhaustive, the search always results in optimum codes for given (k1, V, Λ/Λ′). Tables with binary and ternary optimum codes to partitions of lattices with 8, 9 e 16 cosets, were obtained.

On the integrable perturbations of the Camassa-Holm equation

We present an investigation of the nonlinear partial differential equations (PDE) which are asymptotically representable as a linear combination of the equations from the Camassa-Holm hierarchy. For this purpose we use the infinitesimal transformations of dependent and independent variables of the original PDE. This approach is helpful for the analysis of the systems of the PDE which can be asymptotically represented as the evolution equations of polynomial structure. © 2000 American Institute of Physics.

Remark on the Neves-Wotzasek constraints conversion method

In this work we give an alternative way which generalizes the recently implemented Neves-Wotzasek method of conversion from second to first-class systems. We have proved that this generalization is correct reproducing the results given in the literature using the case of a sphere with an antisymmetric generator as an example. ©2000 The American Physical Society.

Contracted GTF basis sets applied to the theoretical interpretation of the Raman spectrum of hexaaquachromium(III) ion

Contracted GTF basis sets designed with aid of the Generator Coordinate Hartree-Fock (GCHF) method for H(2S), O2-(1S), and Cr3+(4F) atomic species are applied to perform theoretical interpretation of the Raman spectrum of hexaaquachromium(III) ion. The 16s, 16s 10p, and 24s17p13d GTF basis sets were contracted to [4s] for H atom, [6s4p], and [9s6p3d] for O2- and Cr3+, respectively, by Dunning's scheme. For Cr3+, the [9s6p3d] basis set was enriched with f polarization function and used in combination com [4s] and [6s4p] in the study of our interest. The results obtained in this report show that the contracted GTF basis sets used are a useful alternative for the theoretical interpretation of Raman spectrum of hexaaquachromium(III) ion and that GCHF method is an effective alternative to selection of GTF basis sets for theoretical study of vibrational properties of poliatomic species. © 2003 Elsevier Science B.V. All rights reserved.

Integration of the dispersed generators in the distribution management system

Since the 80s huge efforts have been made to utilize renewable energy sources to generate electric power. An important issue about using renewable energy sources is a Distribution Management System (DMS) in presence of dispersed generators. This paper reports some aspects of integration of the dispersed generators in the DMS. Besides, an investigation of impact of the dispersed generators on the overall performances of the distribution systems in steady state is performed. In order to observe losses in the distribution networks with dispersed generators, several loss allocation methods are applied. Results obtained from case study using IEEE test network, are presented and discussed. © 2003 IEEE.

Habitat, distribuição e aspectos adaptativos de peixes da microbacia do ribeirão Grande, Estado de São Paulo, Brasil

The ichthyofauna of ribeirão Grande microbasin that runs through one of the few remaining fragments of Atlantic Forest (in Mantiqueira mountain range, Valley of Paraíba) was studied. Fish samples were obtained with an electric fishing powered by a maximum capacity generator of 155 V and 60-Hz alterning current, gill-nets and traps. In three collecting days, during July/2001, October/2001, January/2002 and April/2002, 2865 fishes were sampled. These fishes belonged to 12 families, 23 genera and 37 species. The species were more abundant between the piedmont and the plain of the Valley of Paraíba. The Characidium, Trichomycterus genera and the Imparfinis minutus species presented only one ovary or testis and no swim bladder. The ecological significance of morphological features in stream mountain fishes was used to predict the niche adaptation for those conditions, towards K-strategy.

Feeding and condition factor of characidiin fish in Ribeirão Grande system, Southeastern Brazil

Feeding, seasonal changes in visceral fat and condition factor were compared in two species of characidiin fishes, Characidium lauroi and C. alipioi from Ribeirão Grande system, southeastern Brazil. Five streams of Ribeirão Grande system were sampled (22° 47' 08 S, 45° 28' 17W). The samples were taken four times per site, from July, 2001 to April, 2002: winter (July 2001), spring (October 2001), summer (February 2002) and autumn (April 2002). Quantitative collections were made with an electro-fishing device powered by a generator with maximum capacity of 1,500 V and 8.7 A of 60 Hz alternating current. Ephemeroptera nymphs, Diptera larvae (Chironomidae, Simuliidae), Plecoptera nymphs, Trichoptera larvae (Hydroptilidae, Psychoyiidae), terrestrial insects (Coleoptera, Isoptera, Hemiptera [Heteroptera, Homoptera]), Megaloptera larvae (Corydalidae), Arachnida, Ostracoda and vegetal debris were found in both species' diets. Visceral fat declined in February, coinciding with the decline of the condition factor in both species. The increased feeding from summer to fall provides fat accumulation. During subsequent seasons, fish may utilize visceral fat reserves for maintenance and reproduction.

Pure spinor formalism as an N ≤ 2 topological string

Following suggestions of Nekrasov and Siegel, a non-minimal set of fields are added to the pure spinor formalism for the superstring. Twisted ĉ ≤ 3 N ≤ 2 generators are then constructed where the pure spinor BRST operator is the fermionic spin-one generator, and the formalism is interpreted as a critical topological string. Three applications of this topological string theory include the super-Poincaré covariant computation of multiloop superstring amplitudes without picture-changing operators, the construction of a cubic open superstring field theory without contact-term problems, and a new four-dimensional version of the pure spinor formalism which computes F-terms in the spacetime action. © SISSA 2005.

On non-linear and non-ideal interactions in two vibrating problems

In practical situations, the dynamics of the forcing function on a vibrating system cannot be considered as given a priori, and it must be taken as a consequence of the dynamics of the whole system. In other words, the forcing source has limited power, as that provided by a DC motor for an example, and thus its own dynamics is influenced by that of the vibrating system being forced. This increases the number of degrees of freedom of the problem, and it is called a non-ideal problem. In this work, we considerer two non-ideal problems analyzed by using numerical simulations. The existence of the Sommerfeld effect was verified, that is, the effect of getting stuck at resonance (energy imparted to the DC motor being used to excite large amplitude motions of the supporting structure). We considered two kinds of non-ideal problem: one related to the transverse vibrations of a shaft carrying two disks and another to a piezoceramic bar transducer powered by a vacuum tube generated by a non-ideal source Copyright © 2007 by ASME.

A true programmable HPF hybrid three-phase rectifier

In this paper is proposed and analyzed a digital hysteresis modulation using a FPGA (Field Programmable Gate Array) device and VHDL (Hardware Description Language), applied at a hybrid three-phase rectifier with almost unitary input power factor, composed by parallel SEPIC controlled single-phase rectifiers connected to each leg of a standard 6-pulses uncontrolled diode rectifier. The digital control allows a programmable THD (Total Harmonic Distortion) at the input currents, and it makes possible that the power rating of the switching-mode converters, connected in parallel, can be a small fraction of the total average output power, in order to obtain a compact converter, reduced input current THD and almost unitary input power factor. The proposed digital control, using a FPGA device and VHDL, offers an important flexibility for the associated control technique, in order to obtain a programmable PFC (Power Factor Correction) hybrid three-phase rectifier, in agreement with the international standards (IEC, and IEEE), which impose limits for the THD of the AC (Alternate Current) line input currents. Finally, the proposed control strategy is verified through experimental results from an implemented prototype. ©2008 IEEE.