154 research outputs found
Standard gradient models and crack simulation
The standard gradient models have been intensively studied in the literature, cf. Fremond (1985) or Gurtin (1991) for various applications in plasticity, damage mechanics and phase change analysis. The governing equations for a solid have been introduced essentially from an extended version of the virtual equation. It is shown here first that these equations can also be derived from the formalism of energy and dissipation potentials and appear as a generalized Biot equation for the solid. In this spirit, the governing equations for higher gradient models can be straightforwardly given. The interest of gradient models is then discussed in the context of damage mechanics and crack simulation. The phenomenon of strain localization in a time-dependent or time-independent process of damage is explored as a convenient numerical method to simulate the propagation of cracks, in relation with some recent works of theliterature, cf. Bourdin Marigo [3], Lorentz al [5], Henry al [12]
Expression and characterization of the nitrile reductase queF from E. coli
AbstractThe expression and characterization of a nitrile reductase from Escherichia coli K-12 (EcoNR), a newly discovered enzyme class, is described. This enzyme has a potential application for an alternative nitrile reduction pathway. The enzyme activity towards its natural substrate, preQ0, was demonstrated and optimal working conditions were found to be at 37°C and at pH 7 with Tris buffer
A Method to Construct an Extension of Fuzzy Information Granularity Based on Fuzzy Distance
In fuzzy granular computing, a fuzzy granular structure is the collection of
fuzzy information granules and fuzzy information granularity is used to
measure the granulation degree of a fuzzy granular structure.
In general, the fuzzy information granularity characterizes discernibility ability
among fuzzy information granules in a fuzzy granular structure. In recent years,
researchers have proposed some concepts of fuzzy information granularity based
on partial order relations. However, the existing forms of fuzzy information granularity
have some limitations when evaluating the fineness/coarseness between two fuzzy
granular structures. In this paper, we propose an extension of fuzzy information
granularity based on a fuzzy distance measure.
We prove theoretically and experimentally that the proposed fuzzy information
granularity is the best one to distinguish fuzzy granular structures.
ACM Computing Classification System (1998): I.5.2, I.2.6
MỐI QUAN HỆ DI TRUYỀN CỦA MỘT SỐ QUẦN THỂ CHIM YẾN SỐNG NGOÀI ĐẢO VÀ TRONG ĐẤT LIỀN Ở VIỆT NAM
Edible-nest Swiftlets (A. fuciphagus) create nests using their solidified saliva. The nests have long been harvested because of their high economic value. This research addresses the phylogenetic relationships of several bird populations in Vietnam based on a portion of the cytochrome b gene with 606bp in length. Phylogenetic analyses show that populations inhabiting islands and mainland belong to different subspecies of A. fuciphagus. Wild swiftlets on islands are assigned to subspecies A. f. germani, while house swiftlets (birds on mainland) are recovered as A. f. amechanus with mean genetic divergence of 1.9%. There are some specific sites for nucleotide substitutions between the two groups (group resident on islands and mainland, respectively): 36 (C-T), 93 (G-C), 96 (C-T), 117 (T-C), 306 (G-A), 468 (G-A), 489 (A-G), 531 (T-C). Our results suggest that the recently recorded house swiftlet populations (subspecies A. f. amechanus) in Vietnam are probably originated from the southern region of Southeast Asia. We recommend that future studies should include nuclear genes (chromosome genes) to evaluate cross-hybrid between the populations.TÓM TẮT Chim yến (Aerodramus fuciphagus) hiện là loài chim có khả năng tạo ra tổ chim hoàn toàn bằng nước bọt được con người khai thác với giá trị kinh tế cao. Các loài trong giống Aerodramus thuộc nhóm chim bay liên tục và rất khó phân biệt về hình thái. Những năm gần đây, số lượng chim yến làm tổ trong nhà yến ở đất liền ngày một gia tăng trải rộng các tỉnh ven biển từ Cà Mau ra tận Thanh Hóa. Phân tích trình tự một phần gen cytochrome b với chiều dài 606bp cho thấy các quần thể chim yến cư trú ngoài đảo (chim yến đảo) thuộc phân loài Aerodramus fuciphagus germani và chim yến làm tổ trong nhà ở đất liền (chim yến nhà) thuộc phân loài A. f. amechanus, vì giữa chúng có sự khác biệt về di truyền trung bình khá cao, tới 1,9%. So sánh phân tích di truyền cho thấy quần thể yến nhà A.f.amechanus ở nước ta được hình thành chủ yếu từ các quần thể chim yến khác nhau ở Thái Lan và Malaysia di cư đến trong khoảng hơn một thập kỉ qua
El trauma de los niños vietnamitas que viven en familias incompletas
Children living in incomplete families have to suffer from more hardships than others including psychological trauma that could never be cured without safe approaches. In this paper, we used the Children Behavior Checklist (CBCL test) by Achenbach to initially filter the incidence of children in incomplete families with psychological trauma, the extent of childhood trauma, and the signs of trauma. Moreover, the Self-esteem scale of Toulouse was also utilized to investigate children's self-esteem and determine the impact of psychological trauma on the self-assessment of children. Based on these tools, the research conducted a correlation analysis of psychological trauma of children in incomplete families through indicators of awareness of, emotions with, and behaviors towards family and social life (self-evaluated by children). The results showed that there are differences in psychological trauma of children in terms of awareness, emotions, and behaviors. The differences allow for a better definition of children's causes, influences, and degrees of psychological trauma. This is the basis for proposing timely filtering solutions and effective psychological support measures for these children.
Keywords: correlation analysis; signs of psychological trauma; children; incomplete family; Vietnam.Los niños que viven en familias incompletas tienen que sufrir más dificultades que otros, incluido el trauma psicológico que nunca podría curarse sin enfoques seguros. En este artículo, se utiliza la Lista de Verificación de Comportamiento Infantil (prueba CBCL) de Achenbach para filtrar inicialmente la incidencia de niños en familias incompletas con trauma psicológico, el alcance del trauma infantil y los signos de trauma. Además, la escala de autoestima de Toulouse también se utilizó para investigar la autoestima de los niños y determinar el impacto del trauma psicológico en la autoevaluación de los niños. Con base en estas herramientas, la investigación realizó un análisis de correlación del trauma psicológico de los niños en familias incompletas a través de indicadores de conciencia, emociones y comportamientos hacia la vida familiar y social (autoevaluados por los niños). Los resultados mostraron que existen diferencias en el trauma psicológico de los niños en términos de conciencia, emociones y comportamientos. Las diferencias permiten una mejor definición de las causas, influencias y grados de trauma psicológico de los niños. Esta es la base para proponer soluciones de filtrado oportunas y medidas de apoyo psicológico eficaces para estos niños.
Palabras clave: análisis de correlación; signos de trauma psicológico; niños; familia incompleta; Vietnam
Genetic variation within and between three Vietnamese pine populations (Pinus merkusii) using random amplified polymorphic DNA (RAPD) markers
Pinus merkusii is an important species in Vietnam with many economic and biological contributions. The information on diversity within and between populations of a species is necessary for plantation programs, breeding and conservation strategies. Genetic diversity of three Vietnamese populations (NA, QB and QN) was analyzed using the random amplified polymorphic DNA (RAPD) markers. Nine RAPD primers produced 82 markers, 77 of which were polymorphic with 93.9% of polymorphism. The results showed higher genetic variation within populations (72%) than between populations (28%) and low Nei’s genetic differentiation index among populations (0.1867). The populations also clustered based on PCoA analysis where cluster I included NA and QB populations and Cluster II, the QN population. These results suggest that P. merkusii populations in Vietnam is necessary to develop the genetic resources.Keywords: DNA markers, genetic diversity, Pinus merkusii, random amplified polymorphic DNA (RAPD), Vietna
Vocational Orientation and the Need for Establishing Career Counselling Office in Vietnamese Schools
School psychology is a field that has been receiving a lot of attention recently in Vietnam as it prepares to restructure the general education curriculum. In particular, vocational orientation and career counseling are most concerned due to the emergence of new subjects in the educational curriculum - Experimental and Vocational Orientation Activities. The objective of this study is to investigate the current situation of vocational orientation problems and the need for career counseling of Vietnamese high school students to provide evidence to develop the school counseling activities and the School Psychology in Vietnam. This is a quantitative study used a questionnaire to examine the current situation of vocational orientation problems and the need for career counseling of 1200 high school students in Vietnam to illustrate the importance of vocational orientation work. The results showed that Vietnamese high school students faced many vocational orientation problems and wanted support from school counselors. But the reality did not meet the needs of students: Vietnamese schools lacked a team of school counselors both in quality and quantity, also lack of school counseling offices in almost high schools. This result is expected to contribute to the development of the School Psychology in Vietnam, but firstly, to promote the establishment of counseling office at least one office per school
Two-Phase Defect Detection Using Clustering and Classification Methods
Autonomous fault management of network and distributed systems is a challenging research problem and attracts many research activities. Solving this problem heavily depends on expertise knowledge and supporting tools for monitoring and detecting defects automatically. Recent research activities have focused on machine learning techniques that scrutinize system output data for mining abnormal events and detecting defects. This paper proposes a two-phase defect detection for network and distributed systems using log messages clustering and classification. The approach takes advantage of K-means clustering method to obtain abnormal messages and random forest method to detect the relationship of the abnormal messages and the existing defects. Several experiments have evaluated the performance of this approach using the log message data of Hadoop Distributed File System (HDFS) and the bug report data of Bug Tracking System (BTS). Evaluation results have disclosed some remarks with lessons learned
Investigation of salt-tolerant rhizosphere bacteria from seawater-intruding paddy rice field in Vietnam
Salt‐tolerant plant growth‐promoting rhizobacteria (ST‐PGPR) are known as potential tools to improve rice salinity tolerance. In this study, we aimed to investigate the plant growth‐promoting rhizobacteria community richness of the paddy rice fields in Soc Trang and Ben Tre Provinces where were seriously affected by sea level rise. The salinity in the sampling sites ranged from 0.14‰ to 2.17‰ in November 2018, the rainy season. The microbial abundance of samples was evaluated by spreading the samples in tryptic soy agar (TSA) medium supplemented with various concentrations of NaCl. With the increase of salt concentration up to 10% NaCl, a total number of bacteria decreased for all the samples, ranging from 106 to 104 CFU/g, and bacterial colonies were not observed at 30% NaCl. Among a total of 48 salt-resisting bacteria isolated from the rice paddy field mud surrounding the rice root, 22 isolates were able to produce indole-3-acetic acid (IAA: phytohormone for the plant growth). Seventeen out of 48 isolates were able to grow in the medium without nitrogen or phosphor sources. Six isolates having high IAA producing activity, nitrogen fixation and phosphate solubilization were belonged to Bacillus (DT6, LT16, and LHT8), Halobacillus (DT8), Aeromonas (LHT1), and Klebsiella (LHT7) genera. All the sequences of the strains DT6, DT8, LT16, LHT1, LHT7, and LHT8 were registered in the GeneBank with the accession numbers MK335670, MK335671, MK335672, MK335673, MK335674, and MK335675, respectively.
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