Constraining the free parameter of the high parton density effects

The high parton density effects are strongly dependent of the spatial gluon distribution within the proton, with radius R, which cannot be derived from perturbative QCD. In this paper we assume that the unitarity corrections are present in the HERA kinematical region and constrain the value of R using the data for the proton structure function and its slope. We obtain that the gluons are not distributed uniformly in the whole proton disc, but behave as concentrated in smaller regions. (C) 2000 Elsevier Science B.V.

Low-energy sector quantization of a massless scalar field outside a Reissner-Nordström black hole and static sources

We quantize the low-energy sector of a massless scalar field in Reissner-Nordström spacetime. This allows the analysis of processes involving soft scalar particles occurring outside charged black holes. In particular, we compute the response of a static scalar source interacting with Hawking radiation using the Unruh (and the Hartle-Hawking) vacuum. This response is compared with the one obtained when the source is uniformly accelerated in the usual vacuum of Minkowski spacetime with the same proper acceleration. We show that both responses are in general different in opposition to the result obtained when the Reissner-Nordström black hole is replaced by a Schwarzschild one. The conceptual relevance of this result is commented on. ©2000 The American Physical Society.

Novos resultados sobre a estabilidade e controle de sistemas nao-lineares utilizando modelos fuzzy e LMI

Relaxed conditions for the stability study of nonlinear, continuous and discrete-time systems given by fuzzy models are presented. A theoretical analysis shows that the proposed method provides better or at least the same results of the methods presented in the literature. Digital simulations exemplify this fact. These results are also used for the fuzzy regulators design. The nonlinear systems are represented by the fuzzy models proposed by Takagi and Sugeno. The stability analysis and the design of controllers are described by LMIs (Linear Matrix Inequalities), that can be solved efficiently by convex programming techniques. The specification of the decay rate, constraints on control input and output are also described by LMIs. Finally, the proposed design method is applied in the control of an inverted pendulum.

Decay of accelerated protons and the existence of the Fulling-Davies-Unruh effect

A theoretic-oriented strategy was taken to address the weak decay of uniformly accelerated protons. The decay of uniformly accelerated p+'s was analyzed using standard quantum field theory (QFT). It was shown that the FDU effect is essential to reproduce the proper decay rate in the uniformly accelerated frame.

Shape-based features for cat ganglion retinal cells classification

This article presents a quantitative and objective approach to cat ganglion cell characterization and classification. The combination of several biologically relevant features such as diameter, eccentricity, fractal dimension, influence histogram, influence area, convex hull area, and convex hull diameter are derived from geometrical transforms and then processed by three different clustering methods (Ward's hierarchical scheme, K-means and genetic algorithm), whose results are then combined by a voting strategy. These experiments indicate the superiority of some features and also suggest some possible biological implications.

Structural, cytochemical, immunocytochemical and ultrastructural characterization of blood granulocytes of the roadside hawk Buteo magnirostris (Gmelin, 1788) (Avian, Falconiform)

In the peripheral blood of the roadside hawk, Buteo magnirostris, the following types of granulocytic leucocytes were identified: heterophil, eosinophil and basophil. The heterophils presented acidophilic and spindle shaped granules, the eosinophils possess spherical eosinophilic granules and the basophils showed spherical and basophilic granules. The heterophils and eosinophils presented positive cytochemical reaction to glycogen and basic polyaminoacid, while the eosinophils presented sudanophilic granules, which were also positive for myeloperoxidase. The heterophils, alone, presented positivity for acid phosphatase in some granules and immunoreactivity to TGF-β1 was observed only in the cytoplasm of the eosinophils. Electron microscopy demonstrated the heterophil granules as predominantly spindle shaped, being strongly electron-dense, while the eosinophils had numerous uniformly electron-dense spherical granules and the basophils presented three different types of granules identified according to their electron-density and the aspect of their matrix.

Comparative study of the fat body in some genera of the attini tribe (Hymenoptera: Formicidae)

The Cyphomyrmex rimosus Spinola and Mycetarotes parallelus Emery species of ants, considered basal, and Acromyrmex disciger Mayr and Atta laevigata Smith, considered derived, have fat bodies specially distributed on their gaster, around their organs and right below the cuticle. The fat body is formed by trophocytes, which are characterized by their pronounced vacuolization of the cytoplasm and the irregular morphology of their nuclei caused by the pressure exerted by cytoplasmic vacuoles. In C. rimosus, the nuclei are more regular, presenting an oval or a star form. In A. disciger and A. laevigata the nuclei present chromatin in a cord form, while in C. rimosus and M. paralellus the chromatin is uniformly distributed in the nucleoplasm, very condensed in the latter species. The parietal trophocytes of A. disciger show cytoplasm with a smaller quantity and smaller sizes of vacuoles compared to ones from the perivisceral region, the opposite is observed in C. rimosus. In A. laevigata and M. parallelus there were no differences observed in their cytoplasm between both regions of cells. In the trophocytes of C. rimosus, A. disciger, A. laevigata, there was a reticular aspect of the cytoplasm observed in the region between vacuoles, not seen on M. parallelus. Another cellular type, oenocyte, was found associated with the fat body cells, and is dispersed between trophocytes with an inner contact to them, but no membrane fusion with them. The oenocytes have a spherical form and are smaller than the trophocytes; they have acidophilic cytoplasm with a small quantity of small vacuoles, and round nuclei.

Bryconamericus turiuba, a new species from the upper Rio Paraná system (Ostariophysi: Characiformes)

Bryconamericus turiuba, new species, is described from the upper Rio Paraná system in Brazil. It differs from all congeners in the following combination of characters: 15-20 branched anal-fin rays; four or five scales in a transverse series from the dorsal-fin origin to the lateral line; shallow body (depth 23.6-30.6% of SL); 37-43 perforated lateral line scales; first, third, and fifth or, more rarely, first and fourth outer premaxillary tricuspid teeth projecting anteriorly; two to five tricuspid to pentacuspid maxillary teeth; dentary with three or four tricuspid or pentacuspid large teeth, followed by five to seven smaller conical to tricuspid teeth; a conspicuous dark, vertically elongate humeral spot, extending to below the lateral line; a dark dorsal stripe extending from the supraoccipital spine to the caudal peduncle with a gap at the adipose-fin base; caudal-fin lobes without conspicuous markings, uniformly pigmented along rays; mature males lacking hooks on the pelvic- and anal-fin rays. The new species is compared with the Bryconamericus species described from the basins of the Rio Paraná, Rio Paraguay, Rio São Francisco, and coastal Brazilian rivers. © 2005 by the American Society of Ichthyologists and Herpetologists.

Hausdorff dimension for non-hyperbolic repellers II: Da diffeomorphisms

We study non-hyperbolic repellers of diffeomorphisms derived from transitive Anosov diffeomorphisms with unstable dimension 2 through a Hopf bifurcation. Using some recent abstract results about non-uniformly expanding maps with holes, by ourselves and by Dysman, we show that the Hausdorff dimension and the limit capacity (box dimension) of the repeller are strictly less than the dimension of the ambient manifold.

Robust control applications for smart truss structure

A finite element modeling of an intelligent truss structure with piezoelectric stack actuators for the purpose of active damping and structural vibration attenuation is presented. This paper concerns with the following issues aspects: the design of intelligent truss structure considering electro-mechanical coupling between the host structure and piezoelectric stack actuators; the H 2 norm approach to search for optimal placement of actuators and sensors; and finally some aspects in robust control techniques. The electro-mechanical behavior of piezoelectric elements is directly related to the successful application of the actuators in truss structures. In order to achieve the desired damping in the interested bandwidth frequency it is used the H ∞ output feedback solved by convex optimization. The constraints to be reached are written by linear matrix inequalities (LMI). The paper concludes with a numerical example, using Matlab and Simulink, in a cantilevered, 2-bay space truss structure. The results demonstrated the approach applicability.

Population dynamics of Ectatomma brunneum (Hymenoptera, Formicidae) under laboratory conditions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Basin problem for Hénon-like attractors in arbitrary dimensions

We prove that Hénon-like strange attractors of diffeomorphisms in any dimensions, such as considered in [2],[7], and [9] support a unique Sinai-Ruelle-Bowen (SRB) measure and have the no-hole property: Lebesgue almost every point in the basin of attraction is generic for the SRB measure. This extends two-dimensional results of Benedicks-Young [4] and Benedicks-Viana [3], respectively.

Active control in flexible plates with piezoelectric actuators using linear matrix inequalities

The study of algorithms for active vibrations control in flexible structures became an area of enormous interest, mainly due to the countless demands of an optimal performance of mechanical systems as aircraft, aerospace and automotive structures. Smart structures, formed by a structure base, coupled with piezoelectric actuators and sensor are capable to guarantee the conditions demanded through the application of several types of controllers. The actuator/sensor materials are composed by piezoelectric ceramic (PZT - Lead Zirconate Titanate), commonly used as distributed actuators, and piezoelectric plastic films (PVDF-PolyVinyliDeno Floride), highly indicated for distributed sensors. The design process of such system encompasses three main phases: structural design; optimal placement of sensor/actuator (PVDF and PZT); and controller design. Consequently, for optimal design purposes, the structure, the sensor/actuator placement and the controller have to be considered simultaneously. This article addresses the optimal placement of actuators and sensors for design of controller for vibration attenuation in a flexible plate. Techniques involving linear matrix inequalities (LMI) to solve the Riccati's equation are used. The controller's gain is calculated using the linear quadratic regulator (LQR). The major advantage of LMI design is to enable specifications such as stability degree requirements, decay rate, input force limitation in the actuators and output peak bounder. It is also possible to assume that the model parameters involve uncertainties. LMI is a very useful tool for problems with constraints, where the parameters vary in a range of values. Once formulated in terms of LMI a problem can be solved efficiently by convex optimization algorithms.

Microstructure evolution during warm deformation of low carbon steel with dispersed cementite

The microstructure evolution and mechanical behavior during large strain of a 0.16%C-Mn steel has been investigated by warm torsion tests. These experiments were carried out at 685°C at equivalent strain rate of 0.1 s . The initial microstructure composed of a martensite matrix with uniformly dispersed fine cementite particles was attained by quenching and tempering. The microstructure evolution during tempering and straining was performed through interrupted tests. As the material was reheated to testing temperature, well-defined cell structure was created and subgrains within lath martensite were observed by TEM; strong recovery took place, decreasing the dislocation density. After 1 hour at the test temperature and without straining, EBSD technique showed the formation of new grains. The flow stress curves measured had a peculiar shape: rapid work hardening to a hump, followed by an extensive flow-softening region. 65% of the boundaries observed in the sample strained to ε = 1.0 were high angle grain boundaries. After straining to ε = 5.0, average ferrite grain size close to 1.5 μm was found, suggesting that dynamic recrystallization took place. Also, two sets of cementite particles were observed: large particles aligned with straining direction and smaller particles more uniformly dispersed. The fragmentation or grain subdivision that occurred during reheating and tempering time was essential for the formation of ultrafine grained microstructure.

Analise da relação entre escorregamento e formas de vertentes no município de cubatão (SP) e seus arredores

The city of Cubatão is a densely populated area with high industrial activity. In the area there are also important linear works as roads, railways, pipelines, aqueducts and lines of transmission of energy. The geological and geomorphological features of the municipality, combined with the human activities, make the site an area heavily prone to the landslides, so a region at high risk. In this work, landslide scars were extracted in aerial photos from 1985 and 1994, years that recorded a high incidence of landslides. Quantitative analysis of the relationship between the occurrence of scars and the forms of tracks were conducted, based on an intensive survey of scars in the region, represented by 2595 extracted scars, with the aim of contributing to a better understanding of the slipping processes in the Serra do Mar paulista and thus to the reduction of risks in the region. Achievements have concluded that the greatest percentage of slides in the region is linked to the strands straitght, followed by convex, which confirms previous studies conducted in the region, in a qualitative way or with a much lower number of scars.