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Acta cientifica venezolana最新文献

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[A HPF application to parallelize a 2-D PDE model]. [一个并行化二维PDE模型的HPF应用]。
Acta cientifica venezolana Pub Date : 2003-01-01
Xiómara Contreras, Emilio Hernández
{"title":"[A HPF application to parallelize a 2-D PDE model].","authors":"Xiómara Contreras,&nbsp;Emilio Hernández","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Many practical numerical applications would require a parallel implementation in order to obtain a satisfactory response in a reasonable amount of time. In this sense, this work shows a parallel implementation of an explicit scheme of finite difference (FD) proposed by Kelly et. al., to solve the Partial Differential Equation (PDE / EDDP) of the Wave Propagation problem in an elastic, homogeneous or heterogeneous, two-dimensional medium. High-Performance-Fortran (HPF) will be used here for this purpose. This report shows measures of time on a PC-Cluster using 1, 2, and 4 processors with different sizes of data grid. In addition, a comparative test is included in which the cluster was initially connected using a Fast-Ethernet card, and then connected by a Myrinet card, using a grid size of 2500 x 2500 in both cases. The execution time achieved with two processors was highly satisfactory for all cases. In analogous conditions, the performance obtained with a Myrinet interconnection was better than the one obtained with a Fast-Ethernet interconnection. The scheme mentioned above has showed an excellent numerical result as it could be seen on the images included in this work. Key words: Partial differential equation, wave equation, explicite finite differences scheme, parallel scheme.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 3","pages":"153-61"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41008805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
[Study of the hydrolytic degradation of a biodegradable copolymer]. [生物可降解共聚物的水解降解研究]。
Acta cientifica venezolana Pub Date : 2003-01-01
Marco A Sabino, Dayanara Morales, Gladys Ronca, José Luis Feijoo
{"title":"[Study of the hydrolytic degradation of a biodegradable copolymer].","authors":"Marco A Sabino,&nbsp;Dayanara Morales,&nbsp;Gladys Ronca,&nbsp;José Luis Feijoo","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The hydrolytic degradation of bioabsorbable Poliglactin 910 was studied in a phosphate buffer solution, pH = 7.4, at 37 degrees C. The degradation was evaluated by analyzing the changes in weight loss, pH, DSC, mechanical properties and morphological changes. After 10 weeks, the weight loss and pH changes suggested diffusion of low molecular weight chain segments into the reaction medium as a consequence of the breaking of ester bonds in the material. Breaking stress and Young Modulus decrease, indicating that chain scission proceeded in two steps: the first occurring in the amorphous regions within the intermicrofibrillar space; the second in the crystalline regions. Surface morphological changes suggest a heterogeneous degradation mechanism by layers.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 1","pages":"18-27"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40828806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
[Lipid profile from low socioeconomic level preschool children. Valencia, Venezuela]. [低社会经济水平学龄前儿童的脂质特征]瓦伦西亚,委内瑞拉)。
Acta cientifica venezolana Pub Date : 2003-01-01
Liseti Solano, Emma Velásquez, Gloria Naddaf, María Páez
{"title":"[Lipid profile from low socioeconomic level preschool children. Valencia, Venezuela].","authors":"Liseti Solano,&nbsp;Emma Velásquez,&nbsp;Gloria Naddaf,&nbsp;María Páez","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Overweight and obesity are a public health problem worldwide affecting adults and children as well. The aim of this study was to assess overweight, lipid profile and cardiovascular risk ratios in 390 preschool children from low socio-economic level from Valencia, Venezuela. Nutritional anthropometric evaluation measured by body dimensions, and serum determination of cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol and cardiovascular risk factors, were determined. 95% of the children were in relative and critical poverty. 14.3% of undernutrition and 20.8% of overweight was found. Lipid profile was in normal range, with no significant differences by sex, but higher values for HDL-cholesterol and risk ratios were found in children aged 1 to 3.99 years. Even though no differences were found by nutritional status, overweight children had higher values for lipids, except HDL-cholesterol. 6.3% of overweight children had cholesterol > or =170 mg/dL, 16.5% LDL-cholesterol > or =110 mg/dL, 40.5% triglycerides > or =75mg/dL and 100% HDL-cholesterol <45 mg/dL. Overweight and lipid profile alterations were present in an important group of the children, which increase their risk of obesity and chronic non-transmissible diseases. Nutritional and educational intervention should be addressed.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 4","pages":"254-62"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40931497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
[MOTRICO project: the mesh generation problem of the human left coronary artery bifurcation]. [MOTRICO项目:人体左冠状动脉分叉的网格生成问题]。
Acta cientifica venezolana Pub Date : 2003-01-01
Francisco J Serón, Elsa García, Jorge del Pico
{"title":"[MOTRICO project: the mesh generation problem of the human left coronary artery bifurcation].","authors":"Francisco J Serón,&nbsp;Elsa García,&nbsp;Jorge del Pico","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The MOTRICO project plans the development of an advanced environment that will offer computer assistance for cardiac therapy and diagnosis, which would be useful in the hemodynamics units of those hospitals that have access to the instrumental techniques of Angiography and intravascular Ultrasounds. The initial work presented in this paper will describe modeling and finite element mesh generation of an idealized model of the human left coronary artery bifurcation. The computational geometric model has been developed on the basis of real anatomical information.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 1","pages":"28-35"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40828807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
[Incorporation of prime and tailing starches of Canavalia ensiformis L. and Phaseolus lunatus L. in cookies]. [在甜饼中加入大黄菜豆和月亮菜豆的起始淀粉和尾淀粉]。
Acta cientifica venezolana Pub Date : 2003-01-01
Alma Chim Rodríguez, Jesús López Luna, David Betancur Ancona
{"title":"[Incorporation of prime and tailing starches of Canavalia ensiformis L. and Phaseolus lunatus L. in cookies].","authors":"Alma Chim Rodríguez,&nbsp;Jesús López Luna,&nbsp;David Betancur Ancona","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Incorporation into cookies of prime and tailing starches isolated from Phaseolus lunatus and Canavalia ensiformis seeds was carried out and compared with those elaborated with conventional corn starch (Maizena), which were sensory evaluated and assessed for total dietary fiber (TDF), insoluble dietary fiber (IDF) and soluble dietary fiber (SDF) contents. Sensory evaluation was carried out using an incomplete block design by a non-trained panel of judges. The analysis of variance indicated a significant difference (p < 0.05), in the level of acceptation, among the different formulations; cookies elaborated with prime starches were preferred. Cookies elaborated with the tailing starches and the control cookie had similar acceptance. The cookies prepared with tailing starches presented TDF, IDF and SDF contents of 9.3, 4.86 and 4.87%, respectively for C. ensiformis and of 9.85, 8.75 and 1.10%, for P. lunatus. These contents were higher than those found in other cookies. The use of prime and tailing starches of Canavalia ensiformis and Phaseolus lunatus may represent an effective alternative in manufacturing of fiber-rich bakery products.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 2","pages":"138-47"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24405430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
[Effect of defatted corn germ flour and rice bran on some chemical, physical and sensory properties of sausages]. 脱脂玉米胚芽粉和米糠对香肠某些化学、物理和感官特性的影响。
Acta cientifica venezolana Pub Date : 2003-01-01
Emperatriz Pacheco-Delahaye, Nilda Vivas Lovera
{"title":"[Effect of defatted corn germ flour and rice bran on some chemical, physical and sensory properties of sausages].","authors":"Emperatriz Pacheco-Delahaye,&nbsp;Nilda Vivas Lovera","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>In order to diversify the use of locally available agricultural byproducts from corn and rice, commercial sausages were prepared using defatted flour of corn germ (DFCG), and stabilized rice bran flour (SRBF) as substitute of the wheat flour in a ration of 30, 50 and 100% and 30% and 50% respectively, and were compared with commercial sausages which contains 3,00% of wheat flour. The sausages showed an increase in its protein content, from 15.68% to 17.70%. The content of dietetic fiber in the enriched sausages increased from 0.90% to 0.98% with DFCG and from 1,0 to 1,1% with SRBF. The stability of the sausages was evaluated by moisture and pH analysis during 60 days at freezing temperature (-16 degrees C), moisture values ranged from 59 to 62% in average and did not show any significant differences, pH values showed a constant behavior with minimum variations without significance (p < 0,05) during storage time. Measurement of color intensity by parameter \"a\" showed a higher tendency to red in the sausages with rice bran. The sensorial evaluation favored this study, since no statistically significant differences were found among the different sausages. In conclusion the results indicate that it is possible to substitute imported wheat flour by locally available byproducts from corn and rice in the preparation of sausages.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 4","pages":"274-83"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40931499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
[Physicochemical and functional evaluation of pregelatinized and microwaved cassava (Manihot esculenta Cranz) starches]. [预糊化和微波木薯淀粉的理化和功能评价]。
Acta cientifica venezolana Pub Date : 2003-01-01
Zurima Mercedes González Parada, Elevina Eduviges Pérez Sira
{"title":"[Physicochemical and functional evaluation of pregelatinized and microwaved cassava (Manihot esculenta Cranz) starches].","authors":"Zurima Mercedes González Parada,&nbsp;Elevina Eduviges Pérez Sira","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The aim of this study was to evaluate the effect of two physical modification methods, drum-drying pregelatinization and microwave heating (at 25% moisture), on some characteristics of cassava starch. The water absorption, solubility and swelling power of pregelatinized starch increased considerably between 65 and 90 degrees C (56 to 86 g water/g starch, 89 to 99% and 63 to 87, respectively), while in microwaved starch these indices dropped, in general terms, from 75 degrees C (5 to 37 g water/g starch, 1 to 37% and 12 to 38 respectively) compared to native starch values (10 to 40 g water/g starch, 2 to 40% and 13 to 41, respectively). All samples showed a marked breakdown during heating, while the pregelatinized starch has the lowest setback values. The morphology of microwaved starch was slightly affected, while in the pregelatinized starch all vestige of granular integrity disappeared. Of the two methods used, pregelatinization caused the most remarkable changes of cassava starch characteristics.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 2","pages":"127-37"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24405429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Noise analysis in bolometer detector for microwave power measurements. 微波功率测热计探测器中的噪声分析。
Acta cientifica venezolana Pub Date : 2003-01-01
Petrizzelli Mario, Luciano Brunetti
{"title":"Noise analysis in bolometer detector for microwave power measurements.","authors":"Petrizzelli Mario,&nbsp;Luciano Brunetti","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>A study of noise related with a thermal detector used as power standard on the 26.5-40GHz frequency band, is presented. This study starts with electromagnetic and thermal analysis, and is based on a cryogenic resistive thermometer functioning at liquid-He temperatures. In addition, the study fixes the theoretical limit of sensitivity.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 3","pages":"199-209"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41008809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
On an analytic estimate in the theory of the Riemann zeta function and a theorem of Báez-Duarte. 黎曼ζ函数理论中的一个解析估计及Báez-Duarte的一个定理。
Acta cientifica venezolana Pub Date : 2003-01-01
Jean-François Burnol
{"title":"On an analytic estimate in the theory of the Riemann zeta function and a theorem of Báez-Duarte.","authors":"Jean-François Burnol","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>On the Riemann hypothesis we establish a uniform upper estimate for zeta(s)/zeta (s + A), 0 < or = A, on the critical line. We use this to give a purely complex-analytic variant of Báez-Duarte's proof of a strengthened Nyman-Beurling criterion for the validity of the Riemann Hypothesis. We investigate function-theoretically some of the functions defined by Báez-Duarte in his study and we show that their square-integrability is, in itself, an equivalent formulation of the Riemann Hypothesis. We conclude with a third equivalent formulation which resembles a \"causality\" statement.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 3","pages":"210-5"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41008810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
[Bone remodelling using the boundary element method]. [基于边界元方法的骨重构]。
Acta cientifica venezolana Pub Date : 2003-01-01
Gabriela Martínez, Miguel Cerrolaza
{"title":"[Bone remodelling using the boundary element method].","authors":"Gabriela Martínez,&nbsp;Miguel Cerrolaza","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>An algorithm for the mathematical representation of external bone remodeling is proposed. The Boundary element method is used for the numerical analysis of trabecular bone, together with the remodeling algorithm presented by Fridez. The versatility and power of the algorithm discussed herein are shown by some numerical examples. As well, the method converges very fast to the solution, which is one of the main advantages of the proposed numerical scheme.</p>","PeriodicalId":75378,"journal":{"name":"Acta cientifica venezolana","volume":"54 1","pages":"76-84"},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40907731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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