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Search Results: 1 - 10 of 226914 matches for " Carlos E.;Castro "
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Generalized Uncertainty Relations, Curved Phase-Spaces and Quantum Gravity  [PDF]
Carlos Castro
Journal of Applied Mathematics and Physics (JAMP) , 2016, DOI: 10.4236/jamp.2016.410189
Abstract: Modifications of the Weyl-Heisenberg algebra \"\" are proposed where the classical limit \"\" corresponds to a metric in (curved) momentum spaces. In the simplest scenario, the 2D de Sitter metric of constant curvature in momentum space furnishes a hierarchy of modified uncertainty relations leading to a minimum value for the position uncertainty . The first uncertainty relation of this hierarchy has the same functional form as the stringy modified uncertainty relation with a Planck scale minimum value for \"\" at \"\" . We proceed with a discussion of the most general curved phase space scenario (cotangent bundle of spacetime) and provide the noncommuting phase space coordinates algebra in terms of the symmetric \"\" and nonsymmetric \"\" metric components of a Hermitian complex metric \"\" , such \"\" . Yang’s noncommuting phase-space coordinates algebra, combined with the Schrodinger-Robertson inequalities involving angular momentum eigenstates, reveals how a quantized area operator in units of \"\" emerges like it occurs in Loop Quantum Gravity (LQG). Some final comments are made about Fedosov deformation quantization, Noncommutative and Nonassociative gravity.
Vascular access-related infections in HIV patients undergoing hemodialysis: case description and literature review
Castro, Carlos E. Figueroa;Madariaga, Miguel G.;
Brazilian Journal of Infectious Diseases , 2008, DOI: 10.1590/S1413-86702008000600017
Abstract: poor immune status, the use of a vascular access different from an av fistula, and intravenous drug use (idu) may favor increased rates of vascular access infections among hiv infected patients on hemodialysis. staphylococcus spp. and streptococcus spp. are the main cause of these infections, but gram-negative rods and fungi have been found as well. using an av fistula when possible, and eliciting a history of ivdu on every visit may prevent this type of infection. when infections are present, coverage for both gram-positive and negative organisms is recommended. additional studies specifically addressing the issue of vascular access infection in hiv infected patients are required.
A amizade e a politiza??o de redes sociais de suporte: reflex?es com base em estudo de ONG/Aids na grande S?o Paulo
Silva, Carlos Roberto de Castro e;
Saúde e Sociedade , 2009, DOI: 10.1590/S0104-12902009000400015
Abstract: the current picture of the hiv/aids epidemic has strengthened the trend of connection with social exclusion, in the sense that the people who are most vulnerable to the infection are those that suffer from the consequences of poverty and/or belong to minority groups. this profile stimulates actions against discrimination and stigmatization, not only related to hiv/aids, but to other forms of discrimination and social oppression associated with the syndrome, such as those related to gender, race/ethnicity, and social class. this study aims to discuss, from the psychosocial point of view, the role of the ngos/aids as promoters of the creation of social support networks, focusing on the process of politicization of the affective bonds of the people who live with hiv/aids (pha) through political participation. this study had its empirical field in a ngo/aids located in the great s?o paulo area. we consider that the ngo can contribute to build new social networks for the pha. thus, we view the ngo/aids as a transition space for people who arrive at the institution searching for aid. through the accounts, we highlight some of the psychosocial aspects that contribute to and/or hinder the process of re-articulation of these pha in new social networks, such as: life trajectories marked by social oppressions and individualism, both aggravated by the impact of hiv/aids; the contradictions derived from living together in the institutional space; and possibilities of transformation of the community bonds through solidarity and citizenship.
HIV/Aids e violência: da opress?o que cala à participa??o que acolhe e potencializa
Silva, Josicleide Maciel da;Silva, Carlos Roberto de Castro e;
Saúde e Sociedade , 2011, DOI: 10.1590/S0104-12902011000300010
Abstract: this exploratory and descriptive study aimed at investigating the relation between violence and vulnerability to hiv-aids infection, specifically, how ngos/aids help individuals infected with hiv-aids face situations of violence. different forms of violence are pointed out, among them, sexual abuse. we consider that the various ways, forms and degrees of violence experienced in infancy and adolescence make people more vulnerable to std/hiv/aids, especially those who experience social exclusion situations. moreover, there must be strong and well-prepared psychosocial supporting networks to meet the demands of people who live with hiv/aids. we conducted semi-directed interviews with professionals of one organization and in-depth interviews with young people, in addition to participant observation. the results indicated that the life history of persons infected with hiv-aids is permeated by violence, which leaves indelible consequences, especially to the family and community ties, making the recovering process very difficult. in the interviews, sexual abuse emerged as the consequence of a context marked by various forms of social oppression. on the other hand, the participation of one ngo/aids has been instrumental in creating a space to facilitate the understanding of the various aspects of violence. we point out the ngo's welcoming service, which facilitated the exchange of experiences and dialogue among infected people, professionals and volunteers. thus, in an environment which tries to politicize the problem, silence, terror and social isolation can be replaced by experiences of empowerment, autonomy, dignity and citizenship.
A dimens?o da ética na pesquisa em saúde com ênfase na abordagem qualitativa
Silva, Carlos Roberto de Castro e;Mendes, Rosilda;Nakamura, Eunice;
Saúde e Sociedade , 2012, DOI: 10.1590/S0104-12902012000100005
Abstract: this article addresses the ethical dimension in health research, relating it more specifically to the qualitative approach, based on contributions of the social sciences and ethnography in particular, as it presupposes building a relationship of trust and respect between researchers and researched subjects that is gradually configured. the ethical aspects permeate qualitative research from the choice of the subject matter, the methodological outlines, analysis of the results, to the commitment of providing a feedback for the researched subjects regarding the obtained information. the ethical aspects presuppose the value of an interpersonal relationship in which the different interests, values and worldviews stand as a possibility or not of a joint construction of knowledge. the choice of a subject or object of study is related to a particular life trajectory in which the researcher should ask himself, at all times, how to conciliate the constitution of an ethical attitude in relation to the researched subjects with his own desires, dreams, curiosities and expectations. the article aims to discuss such dilemmas experienced by the researcher, highlighting the importance of ethics for his personal, professional and socio-political growth, and emphasizing the desire for knowledge autonomy, solidarity with social groups and with people involved in the research. based on the report of a research process, the article intends to contribute to the understanding of how ethical aspects are inextricably linked to research, and also to the researcher, bringing elements to the conduction of qualitative research especially in public health.
An Elementary Derivation of The Black Hole Entropy in Any Dimension
Carlos Castro
Entropy , 2001, DOI: 10.3390/e3010012
Abstract: An elementary derivation of the Black Hole Entropy area relation in any dimension is provided based on the New Extended Scale Relativity Principle and Shannon's Information Entropy. The well known entropy-area linear Bekenstein-Hawking relation is derived. We discuss briefly how to derive the most recently obtained Logarithmic and higher order corrections to the linear entropy-area law in full agreement with the standard results in the literature.
p-Branes as Composite Antisymmetric Tensor Field Theories
Carlos Castro
Physics , 1996, DOI: 10.1142/S0217751X98000597
Abstract: $p'$-brane solutions to rank $p+1$ composite antisymmetric tensor field theories of the kind developed by Guendelman, Nissimov and Pacheva are found when the dimensionality of spacetime is $D=(p+1)+(p'+1)$. These field theories posses an infinite dimensional group of global Noether symmetries, that of volume-preserving diffeomorphisms of the target space of the scalar primitive field constituents. Crucial in the construction of $p'$ brane solutions are the duality transformations of the fields and the local gauge field theory formulation of extended objects given by Aurilia, Spallucci and Smailagic. Field equations are rotated into Bianchi identities after the duality transformation is performed and the Clebsch potentials associated with the Hamilton-Jacobi formulation of the $p'$ brane can be identified with the $duals$ of the original scalar primitive constituents. Different types of Kalb-Ramond actions are discussed and a particular covariant action is presented which bears a direct relation to the light-cone gauge $p$-brane action. A simple derivation of $S$ and $T$ duality is also given. \medskip
An Exact Membrane Quantization from W(Infinity) Symmetry
Carlos Castro
Physics , 1995,
Abstract: An exact quantization of the spherical membrane moving in flat target spacetime backgrounds is performed. Crucial ingredients are the exact integrabilty of the $3D~SU(\infty)$ continuous Toda equation and the quasi-finite highest weight irreducible representations of $W_{\infty}$ algebras. Both continuous and discrete energy levels are found. The latter are found for periodic-like solutions. Membrane wavefunctionals solutions are found in terms of Bessel's functions and plausible relations to singleton field theory are outlined.
D=11 Supermembrane Instantons, W(infty) Strings and the Super Toda Molecule
Carlos Castro
Physics , 1994,
Abstract: Exact instanton solutions to $D=11$ spherical supermembranes moving in flat target spacetime backgrounds are construted. Our starting point is Super Yang-Mills theories, based on the infinite dimensional $SU(\infty)$ group, dimensionally reduced to one time dimension. In this fashion the super-Toda molecule equation is recovered preserving only one supersymmetry out of the $N=16$ that one would have obtained otherwise. It is conjectured that the expected critical target spacetime dimensions for the (super) membrane, ($D=11$) $D=27$ is closely related to that of the $noncritical$ (super) $W_{\infty}$ strings. A BRST analysis of these symmetries should yield information about the quantum consistency of the ($D=11$) $D=27$ dimensional (super) membrane. Comments on the role that Skyrmions might play in the two types of Spinning- Membrane actions construted so far is presented at the conclusion. Finally, the importance that integrability on light-lines in complex superspaces has in other types of solutions is emphasized.
Large Nonlinear $W_{\infty}$ Algebras from Nonlinear Integrable Deformations of Self Dual Gravity
Carlos Castro
Physics , 1994, DOI: 10.1016/0370-2693(95)00467-Y
Abstract: A proposal for constructing a universal nonlinear ${\hat W}_{\infty}$ algebra is made as the symmetry algebra of a rotational Killing-symmetry reduction of the nonlinear perturbations of Moyal-Integrable deformations of $D=4$ Self Dual Gravity (IDSDG). This is attained upon the construction of a nonlinear bracket based on nonlinear gauge theories associated with infinite dimensional Lie algebras. A Quantization and supersymmetrization program can also be carried out. The relevance to the Kadomtsev-Petviashvili hierarchy, $2D$ dilaton gravity, quantum gravity and black hole physics is discussed in the concluding remarks.
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