When to chill an alloy PbSb since the temperature of strained, the size of the grains will be determined by the relation between the rapidity of growth and the rapidity of nucleation. It was utilized the curves of cooling off and an analysis was carried out metallographic to identify the microstructure of this, utilizing the balance of heat was calculated the latent heat of fusion. The study of the caloric transfer in a system metal-mold was carried out by means of discreet numerical solutions, considering the transformation of liquid-solid phase and the convexion natural between the phase liquid and thick of the alloy. The methods utilized were the method of finite volume and the method of line to line. A subcooling off in the sample is observed 3, due to the slow velocity of cooling off, also the size of grain is greater in the sample 1 and the solidification is formed 2 solid phases, ...

This work was supported by the Peruvian science foundation CIENCIACTIVA of CONCYTEC and DAAD-CONCYTEC project (2017–2019). The Research Management Office (DGI) of the the Pontificia Universidad Católica del Perú (PUCP) project 492-2017. The research activity was performed in the framework of the doctoral scholarship of L. F. Flores under the contract number 236-2015-FONDECYT. The authors are also thankful to the Center of Materials Characterization (CAM) and the Institute of Corrosion and Protection (ICP) of the PUCP for the EDX, PL and FTIR measurements.

We present a summary ofthe characteristics of echoes from ionospheric (E and F region) field-aligned irregularities obtained with the Piura VHF radar (~7.0° dip latitude, outside the equatorial electrojet region). Our results are based on (1) intermittent monostatic observations made between 1991 and 1999, (2) continuous monostatic observations made between January 2000 and June 2001, and (3) intermittent interferometric observations since August 2001. Among other important results, we have found that the E-region echoes are stronger and occur more frequently during local summer. In addition, we have observed that the seasonal and daily occurrences of Piura F-region irregularities are similar to the occurrence oftopside ESF irregularities over Jicamarca.

We have used the Piura VHF radar (5° 12’S, 80°38’W, ~7.5°N dip latitude), just outside the equatorial electrojet region, in northern Perú (see Figure 1) to gather echoes from 3-m E region field-aligned irregularities (FAI). Our observations are based on short campaigns of few consecutive days taken since 1995 at different times of the year. E region FAIs over Piura are confined to the 95-120 km altitude and present spectral characteristics similar to type 2 equatorial electrojet (EEJ) echoes. However, despite of being at only 7°N dip latitude, they appear mainly at nighttime and early morning, and thus do not present a temporal similarity to the EEJ. We observe the existence of two well-defined types of echoes: 1) lower E region echoes (95-105 km), and upper E region echoes (105-120 km). The lower echoes present a layering characteristic while the upper layer is more structured....

Thirty strains of V. cholerae O1 Ogawa and 2 Inaba, isolated during the outbreak of 1998, were studied in relation to thier sensibility in front of 10 antibiotics of clinical use. Nine strains were determined (28.1%) resistant to 1 up to 6 antibiotics. The SIDS-PAGE of the studied strains exhibited similar pattern of bands.

Treinta cepas de V. cholerae O1 Ogawa y 2 Inaba, aisladas durante el brote de 1998, fueron estudiados en relación a su sensibilidad frente a 10 antibióticos de uso clínico. Nueve cepas (28.1%) fueron resistentes de 1 hasta 6 antibióticos. El SIDS-PAGE de las cepas estudiadas exhibieron un patrón similar de bandas.

Dendrochronological studies in the peruvian nort coast to find records of past El Niño - Southern Oscillation (ENSO) events began an the ale 80's. The peruvian north coast is the west-most area of South America, close to equator (05o S 80o W) and to the Sechura desert, is a very sensitive area to the climatic changes due to ENSO. An initial selection of several regional trees have been done for study. The study includes phenological observations and tree ring characteristics analysis as well as racial growth control of tree trunks and branches. The species more intensively studied and suitable to fina records due to the ENSO are Palo Santo, Hualtaco and Sapote.

Este documento presenta una lista preliminar de especies de aves, mamíferos, anfibios y reptiles registradas en la Estación Experimental Fundo La Génova (EEFLG), ubicada en la provincia de Chanchamayo en la selva central peruana. Los bosques basimontanos de Yungas del valle Chanchamayo se encuentran mayormente conformados por un mosaico de hábitats en los que abundan los cultivos agrícolas y bosques secundarios. Nuestro trabajo busca contribuir al conocimiento de la fauna silvestre en el valle Chanchamayo, en especial en los bosques impactados por actividades agrícolas. La lista de especies fue construida a partir de los registros realizados entre los años 2010 – 2012 en campos de cultivo de naranjo y bosques secundarios de la EEFLG mediante técnicas de muestreo y registros audiovisuales ocasionales. Las técnicas de muestreo incluyeron redes de neblina (aves y mamíferos volad...

Introducción: El Examen médico nacional (ENAM, por sus siglas en inglés) es una prueba obligatoria que los estudiantes deben realizar después de su internado médico. Con los cambios en la ley, ahora sirve como un requisito para el Servicio de Salud Rural y Urbano-Marginal (SERUMS). Objetivo: Determinar las percepciones de utilidad y preparación para ENAM en diez facultades médicas peruanas. Metodología: un estudio analítico de corte transversal se basó en 11 preguntas de un cuestionario autoadministrado, con un Alfa de Cronbach de 0,65. Las variables se cruzaron según el tipo de universidad, año de estudios y, si se repitieron los cursos, con los modelos lineales generalizados. Resultados: Casi todos ellos (92%) sabían lo que es el ENAM, 82% por lo que servían, 74% pensaron que lo aprobarían, y el 27% percibió que el conocimiento adquirido en su universidad era suficiente...

Esta investigación tuvo como objetivo determinar la estrategia de aprendizaje predominante que se relaciona con el desarrollo de la autonomía de los estudiantes del VII ciclo de una institución educativa pública de Lima. Se desarrolló bajo el tipo sustantivo enmarcado y el enfoque cuantitativo. Su diseño fue no experimental y transversal correlacional. La población estuvo conformada por 171 estudiantes, a quienes se les aplicó dos cuestionarios. Los resultados demostraron que la estrategia de codificación de información ejerce mayor peso en el desarrollo de la autonomía de los estudiantes en cuestión. Así también, es una estrategia de riesgo que significa que un estudiante que no la maneje presentará siempre bajos niveles de aprendizaje autónomo.

364-CONCYTEC-OAJ

The authors would like to acknowledge the financial support of the Peruvian science foundation Cienciactiva in the framework of the DAAD-CONCYTEC joint project (2017-2019), the “Círculo de investigación” project and the Research Management Office (DGI) of the Pontificia Universidad Católica del Perú (PUCP). The research activity was performed in the framework of the doctoral scholarship of K. Tucto and L. Flores from CONCYTEC under the contract numbers 012-2013-FONDECYT and 000236-2015-FONDECYT-DE, respectively. The authors are also grateful to the Center of Microcharacterization (CAM) of the PUCP for the EDX and PL measurements.

In this work, we propose a method to retrieve the thickness and optical constants of dielectric thin films from single optical transmittance measurements. The method is based on the envelope method and requires a simple dispersion model for the real part of the refractive index with few fitting parameters, while the absorption coefficient can be determined without the aid of a dispersion model. The wavelength-dependent optical constants can be obtained even from spectra that exhibit few interference fringes. We have tested the method with simulated and real transmittance data from thin films in the spectral range covering the fundamental absorption. In order to assess the method’s reliability to retrieve the optical constants and optical bandgap, a comparison is performed with the method by Chambouleyron, known as the Pointwise Unconstrained Minimization Approach, and a fit using the C...

This work was partially funded by the AECID (Agencia Española de Cooperación Internacional para el Desarrollo) grant numbers A/3795/05, A/4892/06, A/9727/07 A/4817/06; ACCD (Agència Catalana de Cooperació al Desenvolupament, Generalitat de Catalunya) grant U2006; CCD-UPC (Centre de Cooperació per al Desenvolupament, Universitat Politècnica de Catalunya) to LJdV; and by the CONCYTEC (Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica, Perú) grant 189-2005-CONCYTEC-OAJ. JR's research is supported by grant CP05/0130 of the FIS (Fondo de Investigaciones Sanitarias). The authors thank M.J. Pons and Donna Pringle for assistance in the preparation of the final version of the manuscript. Conflict of interest: No conflict of interest to declare.