Simón Bolívar University

About: Simón Bolívar University is a education organization based out in Caracas, Venezuela. It is known for research contribution in the topics: Population & Crystallization. The organization has 5912 authors who have published 8294 publications receiving 126152 citations.

Uniform discretizations: A new approach for the quantization of totally constrained systems

Abstract: We discuss in detail the uniform discretization approach to the quantization of totally constrained theories. This approach allows to construct the continuum theory of interest as a well defined, controlled, limit of well behaved discrete theories. We work out several finite dimensional examples that exhibit behaviors expected to be of importance in the quantization of gravity. We also work out the case of BF theory. At the time of quantization, one can take two points of view. The technique can be used to define, upon taking the continuum limit, the space of physical states of the continuum constrained theory of interest. In particular we show in models that it agrees with the group averaging procedure when the latter exists. The technique can also be used to compute, at the discrete level, conditional probabilities and the introduction of a relational time. Upon taking the continuum limit one can show that one reproduces results obtained by the use of evolving constants, and therefore recover all physical predictions of the continuum theory. This second point of view can also be used as a paradigm to deal with cases where the continuum limit does not exist. There one would have discrete theories that atmore » least at certain scales reproduce the semiclassical properties of the theory of interest. In this way the approach can be viewed as a generalization of the Dirac quantization procedure that can handle situations where the latter fails.« less

Experimental tests of the new plastic scintillator with pulse shape discrimination capabilities EJ-299-33

Abstract: We have studied the prototype of a new plastic scintillator material (EJ-299-33) engineered for gamma-neutron discrimination. Energy and time resolutions as well as pulse shape discrimination capability have been compared with those of standard plastic and liquid scintillators. EJ-299-33 characteristics are somewhat poorer compared to standard scintillators. However, results obtained with the new plastic material suggest its possible use in basic research (time-of-flight measurements) as well as in Homeland Security applications (neutron/gamma monitoring device).

Ethnicity and Revolution: The Political Economy of Racism in Venezuela

Abstract: When Jun Ishibashi of the University of Tokyo published his 2003 essay "Towards an Opening of the Debate on Racism in Venezuela," he put an end to the myth of racial democracy in Venezuela. Moreover, his work sparked a serious and systematic academic debate on this up-till-now taboo subject, which researchers had always treated in a superficial manner. Racism is a serious problem in Venezuela, and the situation has been exacerbated by the current economic, political, and social struggles under way in the country, where the upper and middle classes are opposing the changes initiated by President Hugo Chavez Frfas and the Bolivarian revolutionary process. The economic crisis that began with the decline in international petroleum prices and the subsequent devaluation of the bolivar on the so-called Black Friday in February 1983 served to expose the existence of profound racism directed not only at Afro-Venezuelan and indigenous inhabitants of the country but also at the popular sectors in general, who are constantly berated by the upper and middle classes opposed to the process of change as "vermin," "mixed-breeds," "Indians," "barefoot," and "rabble." This political economy of racism is nothing more than the historical continuation of the long process of conquest and slavery of the indigenous and Afro-Venezuelan populations that began in 1496. Spokespersons for the right, however, stubbornly uphold the theory of Venezuela's exceptionality with regard to racism. Hans Neumann, for example, argues that "in Venezuela we complain about a lot of things that we think are wrong. But we have some things that should serve as an example to other countries. One is that race is not important in judging a person. In Venezuela racial discrimination is not a factor either in employment or in social or intellectual realms. . . . Prejudice against someone because of the color of his skin does not exist. This is not an obstacle here as it is in other places" (1997: 1).