Papers by Leonardo Espinoza
American Journal of Human Biology, 1995
A sample of 113 boys and 101 girls of the Caracas Mixed-Longitudinal Study was grouped into early... more A sample of 113 boys and 101 girls of the Caracas Mixed-Longitudinal Study was grouped into early, average, and late maturers according to selected cut-off points of the 10th and 90th centiles for age at peak height velocity (APHV). Individual curves were fitted with the cubic spline function, in which height velocity corresponds to the first derivative. Age at menarche (AM) was estimated by recall in a longitudinal context. Differences between groups were assessed with F and t-tests. Girls were approximately 2 years earlier than boys in APHV and thus significantly shorter; their estimated PHV was also significantly lower. APHV in boys and girls occurred 0.4–0.6 years earlier than in European children, which is consistent with a faster tempo of growth of Venezuelan youth. The three maturity groups differed significantly in timing, stature, and AM. Early maturers were taller than average maturers, and the latter were taller than late maturers with maximal differences between the extreme groups at ages 13–14 in boys and 11–12 in girls. Early maturers grew at a faster rate than average maturers, and the latter grew at a faster rate than late maturers up to 13 years in boys and 10–11 years in girls. Despite difficulties encountered in the analysis of mixed-linked longitudinal data, meaningful growth differences were found between maturity groups of urban Venezuelan children. © 1995 Wiley-Liss, Inc.
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Nephrology, 2009
Aim: To evaluate the effect of nutritional counselling on nutritional status in peritoneal dialy... more Aim: To evaluate the effect of nutritional counselling on nutritional status in peritoneal dialysis patients.Methods: Twenty-nine peritoneal dialysis patients were randomly selected to receive conventional nutritional counselling during 6 months of follow up. All patients had monthly clinical and biochemical evaluations, and assessments of dialysis adequacy, inflammation and nutritional status at 0, 3 and 6 months.Results: Moderate-severe malnutrition decreased 28% whereas normal nutrition increased 23% at final evaluation (non-significant). Calorie and protein intake remained stable throughout the study (baseline vs final, calorie: 24 ± 8 vs 23 ± 5 Kcal/kg; protein: 1.1 ± 0.5 vs 1.0 ± 0.3 g/Kg, respectively). On the other hand, triceps (16 ± 6 vs 18 ± 8 mm) and subscapular (17 ± 8 vs 20 ± 5 mm) skinfold thicknesses, and mid-arm circumference (27 ± 3 vs 28 ± 3 mm) significantly increased; mid-arm muscle area displayed a non-significant trend to increase (30 ± 9 vs 31 ± 9 cm2) whereas serum albumin significantly increased at the end of study (2.67 ± 0.46 vs 2.94 ± 0.48 g/dL). At final evaluation, median renal creatinine clearance decreased (6.3 (0.8–15.3) vs 2.0 (0.1–6.3) L/week per 1.73 m2) whereas interleukin-6 increased (2.33 (1.9–7.0) vs 4.02 (2.1–8.4) pg/mL).Conclusion: Even though conventional nutritional counselling, as an isolated measure, did not significantly improve all nutritional parameters, it prevented a greater deterioration during 6 months. Nutritional counselling maintained the nutritional status in spite of a decrease in residual renal function and higher systemic inflammation.
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Universum (talca), 2007
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This paper shows that the proper connection of single-phase-input/single-phase-output power cells... more This paper shows that the proper connection of single-phase-input/single-phase-output power cells to a multi-pulse transformer to form a 7-levels voltage waveform has an important impact on the overall performance of the topology. Particularly, if the topology is used in systems that are connected to an unbalanced AC network and/or feeds an unbalanced load. The topology in combination with the proposed arrange of the power cells and the multi-pulse transformer becomes best suitable for applications where the quality of the voltage and current waveforms are of main concern. In fact, the topology minimizes the problems produced by unbalanced loads even though the single-phase nature of both the input and output of the power cells. Moreover, the proposed arrange acts as a buffer for the AC mains voltage unbalances as they do not have any effect on the load voltages. The paper includes the comparison between a reported alternative to arrange the cells with the proposed approach. Particularly, the voltages and currents are shown for both an unbalanced AC mains and an unbalanced load. Unbalance and distortion factors are included to quantify the advantages of the proposed arrange.
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International Journal of Infectious Diseases, 2008
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Journal of Geophysical Research, 2005
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This work of investigation comprises of a project ampler than it must by objective identify and t... more This work of investigation comprises of a project ampler than it must by objective identify and take advantage of the real possibilities to combine the resources by remittances, own income of producers and the governmental contributions to generate more organization and major investment in the municipality of Hidalgo Durango . One includes how antecedent some characteristics of the government programs
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Development of technologies based on localized states depends on our ability to manipulate and co... more Development of technologies based on localized states depends on our ability to manipulate and control these nonlinear structures. In order to achieve this, the interactions between localized states and control tools should be well modelled and understood. We present a theoretical and experimental study for handling non-propagating hydrodynamic solitons in a vertically driven rectangular water basin, based on the inclination of the system. Experiments have shown that tilting the basin induces non-propagating solitons to drift towards an equilibrium position through a relaxation process. Our theoretical approach is derived from the parametrically driven damped nonlinear Schrödinger equation which models the system. The basin tilting effect is incorporated as a spatially inhomogeneous linear correction on dissipation. A motion law for hydrodynamic solitons can be deduced from these assumptions. The model equation, which includes a constant speed and a linear relaxation term, nicely reproduces the motion observed in our experiment.
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Tetrahedron Letters, 2009
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Tetrahedron-asymmetry, 2009
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The present work details the experience on designing a multiagent system devoted to a dynamic Job... more The present work details the experience on designing a multiagent system devoted to a dynamic Job Shop setting using the PASSI methodology. The agent system is in charge of the planning and scheduling of jobs and their operations on a set of available machines, while considering the materials assigned to each operation. Dynamicity concerns job orders scheduling on-the-fly and the re-schedule caused by changes to the original plan due to clients, machines and material stocks. The system has been modeled with the PASSI Toolkit (PTK) and implemented over the Jade agent platform.
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Papers by Leonardo Espinoza