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.

Eigenvalues of the Schrödinger equation with Coulomb potentials plus linear and harmonic radial terms

Abstract: Analytic approximations for the eigenvalues have been obtained using the two-point quasifractional approximants method. Here we extend and generalize previous work where the method was applied to determine eigenenergies of two-dimensional Coulomb potentials in the presence of a magnetic field of arbitrary strength. We have also shown the advantage of our results with respect to other calculations using the shifted 1/N method or Pade approximants.

Phractocephalus hemiliopterus (Pimelodidae, Siluriformes) from the upper Miocene Urumaco Formation, Venezuela: a further case of evolutionary stasis and local extinction among South American fishes

Abstract: A fossil catfish skull from the upper Miocene Urumaco Formation of Falcon State, Venezuela is identified as Phractocephalus hemiliopterus (Pimelodidae), a living species of the large, lowland rivers east of the Andes. This fossil provides another example, in a growing list of cases, of a long and conservative evolutionary history for an advanced South American riverine fish. The phylogenetic position of Phractocephalus implies that other higher level lineages of Pimelodidae had originated before six Ma. This discovery corroborates geological and other biogeographic evidence for a connection of the ancient Orinoco system to the Caribbean coast river systems of Venezuela. The fossil catfish and other large aquatic vertebrates from the same area suggest former, freshwater communities on the north coast that were much richer than modern faunas. Increasing aridity and loss of large permanent rivers in post-Miocene times has presumably caused local extinction of these communities.

Symmetric Functions in Noncommuting Variables

Abstract: Consider the algebra Q > of formal power series in countably many noncommuting variables over the rationals. The subalgebra Pi(x_1,x_2,...) of symmetric functions in noncommuting variables consists of all elements invariant under permutation of the variables and of bounded degree. We develop a theory of such functions analogous to the ordinary theory of symmetric functions. In particular, we define analogs of the monomial, power sum, elementary, complete homogeneous, and Schur symmetric functions as will as investigating their properties.

The Impact of the COVID-19 Pandemic on Social, Health, and Economy

Abstract: In late December 2019, a series of acute atypical respiratory disease occurred in Wuhan, China, which rapidly spread to other areas worldwide. It was soon discovered that a novel coronavirus was responsible, named the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2, 2019-nCoV). The impact of the COVID-19 pandemic on the population’s health is unprecedented in recent years and the impact on a social level even more so. The COVID-19 pandemic is the most large-scale pandemic on earth this century, and the impact in all life sectors is devasting and directly affected human activity in the first wave. The impact on the economy, social care systems, and human relationships is causing an unprecedented global crisis. SARS-CoV-2 has a strong direct acute impact on population health, not only at the physiological level but also at the psychological level for those who suffer it, those close to them, and the general population, who suffer from the social consequences of the pandemic. In this line, the economic recession increased, even more, the social imbalance and inequity, hitting the most vulnerable families, and creating a difficult context for public institutions to address. We are facing one of the greatest challenges of social intervention, which requires fast, effective, and well-coordinated responses from public institutions, the private sector, and non-governmental organizations to serve an increasingly hopeless population with increasingly urgent needs. Long-term legislation is necessary to reduce the vulnerability of the less fortunate, as well as to analyze the societal response to improve the social organization management of available resources. Therefore, in this scoping review, a consensus and critical review were performed using both primary sources, such as scientific articles, and secondary ones, such as bibliographic indexes, web pages, and databases. The main search engines were PubMed, SciELO, and Google Scholar. The method was a narrative literature review of the available literature. The aim was to assess the effects of the COVID-19 pandemic on population health, where the possible interventions at the health level are discussed, the impact in economic and social areas, and the government and health systems interventions in the pandemic, and finally, possible economic models for the recovery of the crisis are proposed.