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Search Results: 1 - 10 of 309515 matches for " J.; Almeida "
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Nichos tróficos em dípteros caliptrados, no Rio de Janeiro, RJ
Revista Brasileira de Biologia , 1998, DOI: 10.1590/S0034-71081998000400004
Abstract: niche breadth and niche overlap of flies were estimated. the flies were breeding in different environments in rio de janeiro (rural, urban and forest). it were used as a larvae substrate: banana mashed, mouse carcass, fish (sardine), bovine liver, shrimp and fresh human faeces. it were bred 14,294 flies, belonging to four families: calliphoridae, fanniidae, muscidae and sarcophagidae. the greater niche overlap values observed were: rural area: phaenicia cuprina versus chrysomya megacephala; urban area: phaenicia eximia versus sarcodexia innota e p. eximia versus synthesiomyia nudiseta; forest area: p. eximia versus hemilucilia flavifacies. the greater niche breadth recorded were: rural area: peckia chrysostoma; urban area: s. nudiseta and musca domestica; forest area: euboettcheria collusor and p. eximia.
Nichos tróficos em dípteros caliptrados, no Rio de Janeiro, RJ
Revista Brasileira de Biologia , 1998,
Abstract: Foram calculadas a extens o e sobreposi o de nichos tróficos de dípteros caliptrados, criados em variados ambientes do Rio de Janeiro (área rural, urbana e florestal), utilizando-se diferentes substratos de cria o (banana amassada, carca a de camundongo, peixe (sardinha), fígado bovino, camar o e fezes humanas frescas. Foram criadas 14.294 moscas, pertencentes às famílias Calliphoridae, Fanniidae, Muscidae e Sarcophagidae. As maiores sobreposi es de nichos tróficos, entre as espécies, foram assim constatadas: área rural: Phaenicia cuprina versus Chrysomya megacephala; área urbana: Phaenicia eximia versus Sarcodexia innota e P. eximia versus Synthesiomyia nudiseta; área florestal: P. eximia versus Hemilucilia flavifacies. Na área rural, o nicho mais extenso foi o de Peckia chrysostoma; na área urbana, o de S. nudiseta e Musca domestica. Euboettcheria collusor e P. eximia, na floresta, foram as espécies com nichos tróficos mais amplos.
A sequence of weakly monotonic automata with increasing level
J. Almeida,A. Cardoso
International Journal of Algebra , 2013,
Abstract: In this paper, we exhibit a sequence of strongly connected aperiodicweakly monotonic automata, whose level increases with the number ofstates.
O Recado Controverso do Grafite Contemporaneo
Contemporanea : Revista de Comunica??o e Cultura , 2008,
Abstract: We intend to investigate some aspects of the cultural and semiotic process of the contemporary forms of the graffiti. Acting as a practice of textualization on accidental supports, it puts focus on the regime that distributes the relations between text, image and medium. The graffiti elaborates an own way of subjectivation in the contemporary world and of intervening in its cultural mosaic.
A Topology for the Penumbral Magnetic Fields
J. Sanchez Almeida
Physics , 2009, DOI: 10.1007/978-3-642-02859-5_16
Abstract: We describe a scenario for the topology of the magnetic field in penumbrae that accounts for recent observations showing upflows, downflows, and reverse magnetic polarities. According to our conjecture, short narrow magnetic loops fill the penumbral photosphere. Flows along these arched field lines are responsible for both the Evershed effect and the convective transport. This scenario seems to be qualitatively consistent with most existing observations, including the dark cores in penumbral filaments reported by Scharmer et al. Each bright filament with dark core would be a system of two paired convective rolls with the dark core tracing the common lane where the plasma sinks down. The magnetic loops would have a hot footpoint in one of the bright filament and a cold footpoint in the dark core. The scenario fits in most of our theoretical prejudices (siphon flows along field lines, presence of overturning convection, drag of field lines by downdrafts, etc). If the conjecture turns out to be correct, the mild upward and downward velocities observed in penumbrae must increase upon improving the resolution. This and other observational tests to support or disprove the scenario are put forward.
Thermal relaxation of very small solar magnetic structures in intergranules: a process that produces kG magnetic field strengths
J. Sanchez Almeida
Physics , 2001, DOI: 10.1086/321532
Abstract: The equilibrium configuration of very small magnetic fluxtubes in an intergranular environment automatically produces kG magnetic field strengths. We argue that such process takes place in the Sun and complements the convective collapse (CC), which is traditionally invoked to explain the formation of kG magnetic concentrations in the solar photosphere. In particular, it can concentrate the very weak magnetic fluxes revealed by the new IR spectro-polarimeters, for which the operation of the CC may have difficulty. As part of the argument, we show the existence of solar magnetic features of very weak fluxes yet concentrated magnetic fields (some 3 x 10^{16} Mx and 1500 G).
Optical interpretation of special relativity and quantum mechanics
J. B. Almeida
Physics , 2000,
Abstract: The present work shows that through a suitable change of variables relativistic dynamics can be mapped to light propagation in a non-homogeneous medium. A particle's trajectory through the modified space-time is thus formally equivalent to a light ray and can be derived from a mechanical equivalent of Fermat's principle. The similarities between light propagation and mechanics are then extended to quantum mechanics, showing that relativistic quantum mechanics can be derived from a wave equation in modified space-time. Non-relativistic results, such as de Broglie's wavelength, Schroedinger equation and uncertainty principle are shown to be direct consequences of the theory and it is argued that relativistic conclusions are also possible.
A geometric interpretation of the Schützenberger group of a minimal subshift
J. Almeida,A. Costa
Mathematics , 2015,
Abstract: The first author has associated in a natural way a profinite group to each irreducible subshift. The group in question was initially obtained as a maximal subgroup of a free profinite semigroup. In the case of minimal subshifts, the same group is shown in the present paper to also arise from geometric considerations involving the Rauzy graphs of the subshift. Indeed, the group is shown to be isomorphic to the inverse limit of the profinite completions of the fundamental groups of the Rauzy graphs of the subshift. A further result involving geometric arguments on Rauzy graphs is a criterion for freeness of the profinite group of a minimal subshift based on the Return Theorem of Berth\'e et. al.
A Manipulation of Visual Feedback during Gait Training in Parkinson's Disease
Quincy J. Almeida,Haseel Bhatt
Parkinson's Disease , 2012, DOI: 10.1155/2012/508720
Abstract: Visual cues are known to improve gait in Parkinson's disease (PD); however, the contribution of optic flow continues to be disputed. This study manipulated transverse line cues during two gait training interventions (6 weeks). PD subjects ( ) were assigned to one of three groups: treadmill (TG), overground (OG), or control group (CG). Participants walked across lines placed on either treadmills or 16-meter carpets, respectively. The treadmill (TG) offered a reduced dynamic flow from the environment, while lines presented on the ground (OG) emphasized optic flow related to the participant's own displacement. Both interventions significantly improved (and maintained through retention period) step length, thus improving walking velocity. Only the OG improved in the TUG test, while only the TG showed hints of improving (and maintaining) motor symptoms. Since gait improvements were found in both training groups, we conclude that by reducing optic flow, gait benefits associated with visual cueing training can still be achieved. 1. Introduction Individuals with Parkinson’s disease (PD) have been shown to walk with a stooped posture, limited arm swing, slow velocity, and small shuffling steps that can often lead to falls [1]. Sensory cueing strategies such as auditory, tactile, and visual cues have often been used to help walking in PD. Stein and Glickstein [2] suggested that of all these modalities, visual cues are most effective in improving PD gait. It is not clear, however, whether improvements might be the result of improved use of optic flow, greater attention directed towards walking, or cortically driven planning of discrete steps that bypass the basal ganglia. Optic flow is a prominent theory that is often put forward to explain the benefits associated with using transverse lines. This theory suggests that transverse lines improve walking due to the stripes accentuating the flow of the surrounding environment as one moves through space [3, 4]. This notion of optic flow has been strongly supported by Azulay et al. [5] that believe the lines emphasized optic flow which improved gait velocity and stride length in PD participants. Optic flow has been previously manipulated through either virtual reality or a projected tunnel screen [6, 7], and in each case, manipulation was presented by changing the surrounding environment. An interesting method of manipulating visual information from the surrounding environment is to have people walk on a treadmill. Biomechanically, the differences that exist between treadmill and overground walking are negligible [8].
Digital microscopy and image analysis applied to composite materials characterization
Paciornik, S.;d'Almeida, J.;
Matéria (Rio de Janeiro) , 2010, DOI: 10.1590/S1517-70762010000200013
Abstract: digital microscopy was employed to characterize the microstructure of fiber-reinforced composite tubes manufactured by filament winding. optical microscopy was used for void characterization while scanning electron microscopy was used for fiber and layer analysis. acquired images were assembled in mosaics to reveal the microstructure of different cross-sections of the sample. image processing was employed to detect either voids or individual fibers and measure their size, shape and spatial distribution. void spatial distribution was analyzed with two different methods - local analysis and the tessellation method - revealing different behaviors along different cross-sections. fiber layers were automatically detected and their average winding angle and dispersion were analyzed.
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