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Diego Hernandez-Hernandez,Tam Larkin,Nawawi Chouw 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.4
This research addresses experimentally the relationship between the excitation frequency and both hoop and axial wall stresses in a water storage tank. A low-density polyethylene tank with six different aspect ratios (water level to tank radius) was tested using a shake table. A laminar box with sand represents a soil site to simulate Soil-Structure Interaction (SSI). Sine excitations with eight frequencies that cover the first free vibration frequency of the tank-water system were applied. Additionally, Ricker wavelet excitations of two different dominant frequencies were considered. The maximum stresses are compared with those using a nonlinear elastic spring-mass model. The results reveal that the coincidence between the excitation frequency and the free-vibration frequency of the soil-tank-water system increases the sloshing intensity and the rigid-like body motion of the system, amplifying the stress development considerably. The relationship between the excitation frequency and wall stresses is nonlinear and depends simultaneously on both sloshing and uplift. In most cases, the maximum stresses using the nonlinear elastic spring-mass model agree with those from the experiments.
Edgar Hernandez Sosa,Yulianis Martín Castejón,Alexander Batista Duharte,Deivys Portuondo,Vivian Tamayo,Humberto J. Morris Quevedo,Clara Esther Martínez Manrique 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.9
Trichilia hirta (Family Meliaceae) is a tree traditionally used in the folk medicine of Cuba to treat asthma, cancer, and ulcers. The objective of this study was to determine the phytochemical composition of ethanol extracts obtained from leaves, roots, and stem bark and to evaluate the leukocyte-stimulating effect of T. hirta root extracts on BALB/c mice. The chemical composition of the extracts was determined by phytochemical screening. Saponins, tannins, flavonoids, and coumarins were detected in extracts of T. hirta. The leukocyte-stimulating effect was evaluated by oral application of ethanol extracts (81.8 and 976 mg/kg) in BALB/c mice for 7 days. The application of 976 mg of extract/kg increased the total leukocyte count up to 15–33%; this effect was significant for neutrophil counts compared with control animals (P<.05). In addition, a dose of 82 mg/kg significantly increased total leukocytes at day 4 of the study (P<.05). The results indicated that T. hirta extracts contain phytochemicals reported as immunostimulants. The administration of these extracts to BALB/c mice indicated that ethanol extract could exhibit leukocyte-stimulating properties and makes it a promising alternative for the development of an immunoprotective agent.
Tapia-Hernandez, Alejandro,Ponce-Silva, Mario,Olivares-Peregrino, Victor Hugo,Valdez-Resendiz, Jesus Elias,Hernandez-Gonzalez, Leobardo The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.4
The main contribution of this paper is the use of sensorless active diodes to generate the gate signals for a three-phase boost-rectifier with a self-powered control scheme. The sensorless operation is achieved making use of the gate control signals generated by the active diode schemes on each of the switching devices using a pulse width half-controlled boost rectifier modulation technique (PWM-HCBR). The proposed scheme synchronizes the gate control signals with a three phase voltage supply. Autonomous operation is obtained making use of the output DC bus to feed the control circuitry, the active diodes and the driver circuitry. The three-phase boost-rectifier is supplied by a three-phase permanent magnet electric generator powered by a solar concentrator dish with variable voltage and variable frequency conditions. Experimental results report an efficiency of up to 94.6% for 25 W and an input of 3.6 V peak per phase with 450.
Alejandro Tapia-Hernandez,Mario Ponce-Silva,Victor Hugo Olivares-Peregrino,Jesus Elias Valdez-Resendiz,Leobardo Hernandez-Gonzalez 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.4
The main contribution of this paper is the use of sensorless active diodes to generate the gate signals for a three-phase boost-rectifier with a self-powered control scheme. The sensorless operation is achieved making use of the gate control signals generated by the active diode schemes on each of the switching devices using a pulse width half-controlled boost rectifier modulation technique (PWM-HCBR). The proposed scheme synchronizes the gate control signals with a three phase voltage supply. Autonomous operation is obtained making use of the output DC bus to feed the control circuitry, the active diodes and the driver circuitry. The three-phase boost-rectifier is supplied by a three-phase permanent magnet electric generator powered by a solar concentrator dish with variable voltage and variable frequency conditions. Experimental results report an efficiency of up to 94.6% for 25 W and an input of 3.6 V peak per phase with 450.
Vitamin D and its effects on cardiovascular diseases: a comprehensive review
( Nonanzit Perez-hernandez ),( Gad Aptilon-duque ),( Maria Cristina Nostroza-hernandez ),( Gilberto Vargas-alarcon ),( Jose Manuel Rodriguez-perez ),( Ruben Blachman-braun ) 대한내과학회 2016 The Korean Journal of Internal Medicine Vol.31 No.6
Vitamin D is a molecule that is actively involved in multiple metabolic pathways. It is mostly known for its implications related to calcium metabolism. It has also been determined that it actively participates in the cardiovascular system, influencing blood pressure, coronary artery disease and other vascular diseases, such as heart failure and atrial fibrillation. Furthermore, it has been established that this vitamin is extensively involved in the regulation of both the renin angiotensin aldosterone system and the immune system. In this review, we present the different vitamin D metabolic pathways associated with the cardiovascular pathophysiology, and we include studies in animal and human models, as well as some of the controversies found in the literature. This review also incorporates an overview of the implications in the molecular biology and public health fields.
Nutritional aspects of night eating and its association with weight status among Korean adolescents
Hernandez, Emely,Kim, Meeyoung,Kim, Won Gyoung,Yoon, Jihyun The Korean Nutrition Society 2016 Nutrition Research and Practice Vol.10 No.4
BACKGROUND/OBJECTIVES: A growing body of research has indicated that night eating could be associated with poor diet quality and negative health outcomes. This study examined the nutritional aspects of night eating, its related factors, and the association between night eating and body weight among Korean adolescents. SUBJECTS/METHODS: This study analysed the data from a one day 24-hour dietary recall as well as a demographic survey of 1,738 Korean adolescents aged 12 to 18-years-old obtained from the 2010-2012 Korea National Health and Nutrition Examination Survey. 'Night eating' was defined as consuming 25% or more of one's daily energy intake between 21:00 and 06:00. Subjects complying with the preceding condition were classified as 'night eaters', whereas the rest were considered 'non-night eaters'. Logistic regression analysis examined factors related to night eating. Multiple linear regression analyses were used to examine the relationship between night eating and BMI z-scores, whereas multinomial logistic regression analysis was used to examine the relationship between night eating and weight status. RESULTS: About 21% of Korean adolescents appeared to be night eaters. Night eaters showed increased breakfast skipping (P = 0.001), higher energy intake from snacks (P < 0.001), greater proportion of energy intake from fat (P = 0.029), and lower Dietary Diversity Scores (P = 0.008) than non-night eaters. Male adolescents presented 1.9 times higher odds of being night eaters than females. Adolescents whose both parents were night eaters were 4.4 times as likely to be night eaters as those whose neither parents were. Female adolescents showed a significant relationship between night eating and BMI z-scores (${\beta}=0.28$, P = 0.004). However, night eating did not increase odds of being overweight or obese in adolescents. CONCLUSIONS: Night eating in Korean adolescents was related to undesirable dietary behaviours and low diet quality in general as well as higher BMI z-scores in females. Male gender and parental night eating appeared to be the factors that significantly increased odds of night eating. These results suggest that night eating should be considered when designing nutrition education or intervention programs targeting adolescents.
Physical Modeling of SiC Power Diodes with Empirical Approximation
Hernandez, Leobardo,Claudio, Abraham,Rodriguez, Marco A.,Ponce, Mario,Tapia, Alejandro The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.3
This article presents the development of a model for SiC power diodes based on the physics of the semiconductor. The model is able to simulate the behavior of the dynamics of the charges in the N- region based on the stored charge inside the SiC power diode, depending on the working regime of the device (turn-on, on-state, and turn-off). The optimal individual calculation of the ambipolar diffusion length for every phase of commutation allows for solving the ambipolar diffusion equation (ADE) using a very simple approach. By means of this methodology development a set of differential equations that models the main physical phenomena associated with the semiconductor power device are obtained. The model is developed in Pspice with acceptable simulation times and without convergence problems during its implementation.
Tuberculosis in Mexico and the USA, Comparison of Trends Over Time 1990-2010
Hernandez-Garduno, Eduardo,Mendoza-Damian, Fabiola,Garduno-Alanis, Adriana,Ayon-Garibaldo, Salvador The Korean Academy of Tuberculosis and Respiratory 2015 Tuberculosis and Respiratory Diseases Vol.78 No.3
Background: The aim was to compare tuberculosis trends in Mexico and United States and to evaluate Mexican diagnostic methods and contact investigation. Methods: Retrospective comparative study of tuberculosis cases and incidence rates between both countries (1990-2010). Diagnostic methods and contact investigations were also evaluated for Mexico. Estimates were obtained from official websites. Results: In Mexico, no clear trend was found over time for cases. Pulmonary (PTB) and all forms of tuberculosis (AFTB) incidence decreased 2.0% annually. There was a negative correlation between the mean contacts examined per case and AFTB incidence ($r^2=-0.44$, p=0.01) with a 33% reduction in AFTB incidence. In United States, PTB and AFTB cases have been decreasing 6.0% and 5.6% annually, respectively. The incidence decreased 7.3% and 6.8%, respectively. Conclusion: The incidence of tuberculosis in Mexico is decreasing slightly over time at 2% annually. In the United States, cases and incidence rates have been decreasing at a higher rate (5% to 7% annually). The inverse association between number of contacts examined per state and incidence rates in Mexico underscore the importance of reinforcing and improving contact investigations with the likely translation of a decrease of TB incidence at a higher rate.