Universidad del Norte, Colombia

About: Universidad del Norte, Colombia is a education organization based out in Barranquilla, Colombia. It is known for research contribution in the topics: Population & Context (language use). The organization has 3562 authors who have published 4355 publications receiving 37861 citations. The organization is also known as: University of the North, Colombia & Uninorte.

Structural, optoelectronic, and thermodynamic properties of Y $$_x$$ x Al $$_{1-x}$$ 1 - x N semiconducting alloys

Abstract: The structural, electronic, optical, and thermodynamic properties of Y $$_x$$ Al $$_{1-x}$$ N alloys were computed using first-principles calculations. The effects of exchange and correlation have been considered by means of the generalized gradient approximation (GGA) with the Perdew–Burke–Ernzerhof parametrization. In addition, the Tran–Blaha-modified Becke–Johnson potential (TB-mBJ) was applied to give a better description of the band-gap energies and optical spectra. The lattice parameters, bulk modulus, and band-gap energy show nonlinear dependence on concentration x. Results for rock-salt Y $$_x$$ Al $$_{1-x}$$ N alloys show that the band gap undergoes an indirect ( $$\Gamma \rightarrow X$$ )-to-direct ( $$\Gamma \rightarrow \Gamma $$ ) transition at a given yttrium composition, followed by a direct ( $$\Gamma \rightarrow \Gamma $$ )-to-indirect ( $$\Gamma \rightarrow X$$ ) transition in a higher yttrium concentration. For wurtzite Y $$_x$$ Al $$_{1-x}$$ N alloys, the band gap presents a direct ( $$\Gamma \rightarrow \Gamma $$ )-to-indirect ( $$M\rightarrow \Gamma $$ ) transition at a given yttrium composition, followed by an indirect ( $$M\rightarrow \Gamma $$ )-to-indirect ( $$M\rightarrow \Sigma $$ ) transition in a higher yttrium concentration. The real dielectric function, imaginary dielectric function, refractive index, and extinction coefficient were calculated using the TB-mBJ potential. Using a regular solution model, slightly lower mixing enthalpies for wurtzite Y $$_x$$ Al $$_{1-x}$$ N alloys were found. The mixing enthalpy for a given concentration differs depending on structures, and on the interaction between atoms of constituents. The effect of temperature on the volume, bulk modulus, Debye temperature, and the heat capacity for Y $$_x$$ Al $$_{1-x}$$ N alloys was analyzed using the quasi-harmonic Debye model. Results show that the heat capacity is fairly sensitive to composition as temperature increases.

Redes atencionales y sistema visual selectivo

Abstract: In this paper we checked the principal researches and theories to explain the attention system functioning. We are going to start reviewing along time about the concept of attention, from filter theories and resources distributor theories, to the current theories in which attention is conceived as a control system. From this last point of view, we will emphasize on the attentional networks theory of Posner, that proposes different systems to explain diverse aspects of attention, but they are related to each other. At last in this paper, we will mention experimental results that have been important to characterize the selective attentional mechanisms of the human visual system, using the attentional spotlight model for this aim.

Visceral Leishmaniasis IgG1 Rapid Monitoring of Cure vs. Relapse, and Potential for Diagnosis of Post Kala-Azar Dermal Leishmaniasis.

Abstract: Background: There is a recognized need for an improved diagnostic test to assess post-chemotherapeutic treatment outcome in visceral leishmaniasis (VL) and to diagnose post kala-azar dermal leishmaniasis (PKDL). We previously demonstrated by ELISA and a prototype novel rapid diagnostic test (RDT), that high anti-Leishmania IgG1 is associated with post-treatment relapse versus cure in VL. Methodology: Here, we further evaluate this novel, low-cost RDT, named VL Sero K-SeT, and ELISA for monitoring IgG1 levels in VL patients after treatment. IgG1 levels against L. donovani lysate were determined. We applied these assays to Indian sera from cured VL at 6 months post treatment as well as to relapse and PKDL patients. Sudanese sera from pre- and post-treatment and relapse were also tested. Results: Of 104 paired Indian sera taken before and after treatment for VL, when deemed clinically cured, 81 (77.9%) were positive by VL Sero K-SeT before treatment; by 6 months, 68 of these 81 (84.0%) had a negative or reduced RDT test line intensity. ELISAs differed in positivity rate between pre- and post-treatment (p = 0.0162). Twenty eight of 33 (84.8%) Indian samples taken at diagnosis of relapse were RDT positive. A comparison of Indian VL Sero K-SeT data from patients deemed cured and relapsed confirmed that there was a significant difference (p < 0.0001) in positivity rate for the two groups using this RDT. Ten of 17 (58.8%) Sudanese sera went from positive to negative or decreased VL Sero K-SeT at the end of 11–30 days of treatment. Forty nine of 63 (77.8%) PKDL samples from India were positive by VL Sero K-SeT. Conclusion: We have further shown the relevance of IgG1 in determining clinical status in VL patients. A positive VL Sero K-SeT may also be helpful in supporting diagnosis of PKDL. With further refinement, such as the use of specific antigens, the VL Sero K-SeT and/or IgG1 ELISA may be adjuncts to current VL control programmes.

Factores que influyen en la elección de las carreras de pedagogía en Colombia

Abstract: Resumen El presente trabajo tiene como objetivo identificar los factores que influyen sobre las motivaciones, la satisfaccion y expectativas en torno al ejercicio profesional en estudiantes de las facultades de Educacion y ciclos complementarios de Escuelas Normales Superiores (ENS) en Colombia, tomando caso de estudio la region Caribe de este pais. Para ello, se aplico un estudio de tipo cuantitativo, cuya muestra estuvo integrada por 805 estudiantes de programas afines a los antes mencionados, quienes estuvieron a cargo del diligenciamiento de una encuesta orientada a la medicion de los factores que influyen en la eleccion de estos estudios, de acuerdo con la escala FIT-choice (Factors Influencing Teaching choice), desarrollado por Watt y Richardson (2007). Los resultados obtenidos no solo nos permiten establecer un perfil socioeducativo de los futuros maestros analizados en este trabajo; sino tambien, facilitan la identificacion de los factores vinculados a los principales tipos de motivaciones que tienen mayor peso, al momento de elegir carreras relacionadas con la Pedagogia; siendo las motivaciones de tipo altruistas e intrinsecas las mas valoradas por los estudiantes encuestados. Las motivaciones extrinsecas, relacionadas con el salario y la conciliacion, por ejemplo, tuvieron una valoracion menor, con la excepcion del factor relacionado con la seguridad del trabajo. La satisfaccion de la eleccion es elevada pese al bajo salario, la falta de estatus social y una alta disuasion social.