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    ABSTRACT: The knowledge about the existence of annual tree rings in tropical trees, which was already found at the beginning of the last century, was ignored by many scientists for a long time. Wood samples of 80 tree species from seven different sites belonging to Satipo and Chanchamayo provinces in Central Forest, Perú. Wood slices were taken at 1.30 m height, following the Peruvian Technical Norms (NTP) 251-008, COPANT norms 30:1-019 and IAWA (1989). Results showed that 24 of the 80 tree species analyzed showed a potential for dendrocronological studies, 25 had problems for growth-rings analysis, and 31 did not have potential. The problems most frequently found were: barely visible or irregular ring growth, parenchyma bands and multiseriate rays difficult to be identified in rings growth. The "T" Student test showed that the significant variation in vessel and fiber diameters between growth zones (Early-wood and late-wood) of species with potential for dendrocronology, do have a periodic cells production, so is possible to suggest the annual formation of each growth-ring. However, those species without potential to dendrocronology may be influenced by of a lot of factors, such as biotic and abiotic conditions of environment, as well as the genetic aspect of each species.
    Revista de biologia tropical 09/2013; 61(3):1025-37.
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    ABSTRACT: Objectives. To determine blood-lead (Pb) levels in pregnant women and neonates in a metallurgical city of Peru. Materials and methods. A cross-sectional study was carried out, the population of which consisted of pregnant women who had lived for at least two years in the city of La Oroya, at the time when the lead, copper and zinc foundries operated normally. A blood sample was obtained from the pregnant women before delivery and, after delivery, from the neonate's umbilical cord and placenta. Lead levels in those samples were measured by graphite furnace atomic absorption spectrophotometry. Pearson's squared regressions and correlations were determined. Results. Forty normal deliveries were studied. The average blood lead levels in the mother, umbilical cord and placenta were 27.4 ± 15.6 ug/dL; 19.0 ± 12.6 ug/dL and 319.0 ± 215.9 ug/100 g, respectively. 67.5% of the neonates registered levels higher than 10 ug/dL. Pb levels in the umbilical cord accounted for 69.4% of Pb level in maternal blood. The correlation coefficients between Pb levels in maternal blood and umbilical cord, maternal blood and placenta, and placenta and umbilical cord were 0.36; 0.48 and 0.33, respectively. Conclusions. At the time the foundry operated, pregnant women and newborns had high blood lead concentrations. Pb concentrations in the placenta and umbilical cord had moderate correlation with the Pb levels in maternal blood. Pb levels in maternal blood and umbilical cord were 1.5 times as high as in more distant areas.
    Revista peruana de medicina experimental y salud publica 09/2013; 30(3):393-398.
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    ABSTRACT: In this paper, the integration of the GIS database and application software is illustrated by using a three-phase distribution power flow. The database can be used for inventory, facility management engineering analysis and map productions. Facility data or network model can be retrieved from the data base. The work describes a complete modeling of elements in a distribution system. The paper report: lines, transformer, load and shunt Var elements. The system configuration can be any combination of single, two and three phase circuits The effects of neutral and ground return paths are include. Transformer losses (core and leakage) and lines losses can be clearly identified in a quantitative manner. This paper will discuss a method to simulate the system in a rigorous way, because a typical feeder involves three-phase, two phase and single phase lateral lines. Finally we report the use of this system in Peru for the study of the Valor Agregado de Distribution (VAD)-yard stick competition - in order to obtain the electric rates in Peru for the next 4 years. The load forecasting is obtained from a hybrid system of case based reasoning and expert systems.
    Transmission and Distribution Conference and Exposition: Latin America, 2004 IEEE/PES; 12/2004

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European Physical Journal C 64(4):637-644.
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International journal of genomics. 01/2013; 2013:624681.
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