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排序方式: 共有369条查询结果,搜索用时 15 毫秒
41.
Betsy Lozoff Nancy K. Klein Edward C. Nelson Donna K. McClish Martin Manuel Maria Elena Chacon 《Child development》1998,69(1):24-36
This study tested the hypothesis that infants with iron-deficiency anemia show behaviors, such as increased proximity to caregivers, increased wariness or hesitance, and decreased activity, that could contribute to “functional isolation.” The behavior of 52 Costa Rican 12- to 23-month-old infants with iron-deficiency anemia was contrasted with that of 139 comparison group infants with better iron status during free play and mental and motor testing and in the home. Infants with iron-deficiency anemia maintained closer contact with caregivers; showed less pleasure and delight; were more wary, hesitant, and easily tired; made fewer attempts at test items; were less attentive to instructions and demonstrations; and were less playful. Adult behavior also differed. The results indicate that iron-deficiency anemia in infancy is associated with alterations in affect and activity, suggesting that functional isolation is a useful framework for understanding poorer developmental outcome in iron-deficiency anemia, the world's most common single nutrient deficiency. 相似文献
42.
43.
Nowadays, almost all curricula in the social sciences contain at least one course in statistics, given the importance of this discipline as an analytical tool. This work identifies the latent factors relating to students' motivation and attitude towards statistics, tests their covariance structure for samples of both sexes, and identifies the possible differences between the sexes. Specifically, using a structural equations model the work confirms that the evaluative factors affect the affective factors and the interest variable affects the level of anxiety. The findings obtained using the partial least squares method allow the authors to confirm the proposed relations and validate the model. 相似文献
44.
The aim of this work was to identify, synthesize and evaluate the results of randomized controlled trials examining the effects of resistance training on performance indicators in previously trained endurance runners. A database search was carried out in PubMed, Science Direct, OvidSPMedLine, Wiley, Web of Science, ProQuest and Google Scholar. In accordance with the PRISMA checklist, 18 published articles dated prior to May 2016 involving 321 endurance runners were reviewed using the PEDro scale. Resistance training led to general improvements in muscular strength, running economy, muscle power factors, and direct performance in distances between 1,500 and 10,000 m. Such improvements were not accompanied by a significant increase in body mass or signs of overtraining. However, improvements did not occur in all cases, suggesting that they might depend on the specific characteristics of the resistance training applied. Although current evidence supports the effectiveness of resistance training to improve performance in already trained endurance runners, the methodological inconsistencies identified suggest that the results should be interpreted with caution. Future studies ought to investigate the benefits of resistance training in endurance runners while considering the existence of possible differentiated effects based on the specific characteristics of the resistance training carried out. 相似文献
45.
Luca Merigo Manuel Beschi Fabrizio Padula Antonio Visioli 《Journal of The Franklin Institute》2018,355(2):774-802
In this paper we propose a new event generator, which has strong noise-filtering capabilities, to be used in event-based control systems with a PIDPlus controller. An approximate frequency analysis is performed in order to characterize the event generator system and tuning guidelines are provided for its design parameter. Simulation and experimental results obtained with a laboratory setup demonstrate the effectiveness of the methodology in providing a satisfactory performance related to set-point and load disturbance step responses with a total variation that is significantly reduced with respect to the standard cases. 相似文献
46.
Tania Socorro Amorim Soares Federico Pizzuto Rui Manuel Garganta João Paulo Vila-Boas Mario Casimiro da Anunciação Paiva 《Journal of sports sciences》2018,36(7):766-770
The effects of running with or without shoes on injury prevention have been extensively studied, and several investigations have assessed biomechanical differences between them. However, findings are not consensual and further insights on biomechanical load associated with differently shod or barefoot conditions may be needed. This study aimed to observe if habitually shod marathon runners show acute alterations when running barefoot or with minimalist shoes, and to determine whether the running kinematical adaptations of wearing minimalist shoes were similar to barefoot running. Twelve male marathon runners ran on the treadmill at their average marathon pace in different footwear conditions: habitual running shoes, minimalist shoes, and barefoot. High-resolution infrared cameras and visual 3D software were used to assess kinematic data. The following parameters were studied: foot strike angle, cycle time, stance time, normalized stride length, hip, knee, and ankle angular position at initial contact, and their respective range-of-motion (ROM) during stance phase. Contrary to the expectations, it was found that highly trained habitually shod elite marathon runners changed their lower limb kinematic pattern both when running barefoot or wearing minimalist shoes. Minimalist shoes showed a trend towards intermediate biomechanical effects between running with and without shoes. 相似文献
47.
Jason L. Selwitz Birgitte Ahring Manuel Garcia-Perez Judith Morrison 《Community College Journal of Research & Practice》2018,42(6):405-421
Community and technical colleges serve a vital function in STEM education by training workers for medium- and high-skilled technical careers and providing employers the labor necessary to operate and maintain thriving business ventures. A curriculum developed with the elements of a systems-based approach results in a program more relevant to the needs of the institution, its students, and industry partners—and avoids the pitfalls of programs designed without a plan or process in place. To achieve validity and reliability, curriculum assessment tools should be conduits to collect critical feedback from students, graduates, and the industries and academic partners served. Research was undertaken to design and evaluate an associate degree-level STEM workforce education program at the nexus of bioenergy/bioproducts, electrical systems and maintenance, and wastewater treatment plant operations. Component to the research, a program’s graduates were interviewed and professionals representing a spectrum of manufacturing/processing-type industries were surveyed. A curriculum development and assessment model emerged to help community and technical college faculty and administrators develop, evaluate, and revise associate degree-level STEM workforce education programs. 相似文献
48.
Manuel TORAL IBAEZ Margarita CARU Miguel A.HERRERA Luis GONZALEZ Luis M.MARTIN Jorge MIRANDA Rafael M.NAVARRO-CERRILLO 《Journal of Zhejiang University. Science. B》2009,10(2)
A protocol of polymerase chain reaction-random amplified polymorphic DNAs (PCR-RAPDs) was established to analyse the gene diversity and genotype identification for clones of Sequoia sempervirens (D.Don) Endl.in Chile.Ten (out of 34) clones from introduction trial located in Voipir-Viilarrica,Chile,were studied.The PCR-RAPDs technique and a modified hexadecyltrimethylammonium bromide (CTAB) protocol were used for genomic DNA extraction.The PCR tests were carried out employing 10-mer random primers.The amplification products were detected by electrophoresis in agarose gels.Forty nine polymorphic bands were obtained with the selected primers (BG04,BF07,BF 12,BF13,and BF 14) and were ordered according to their molecular size.The genetic similarity between samples was calculated by the Jaccard index and a dendrogram was constructed using a cluster analysis of unweighted pair group method using arithmetic averages (UPGMA).Of the primers tested,5 (out of 60) RAPD primers were selected for their reproducibility and high polymorphism.A total of 49 polymorphic RAPD bands were detected out of 252 bands.The genetic similarity analysis demonstrates an extensive genetic variability between the tested clones and the dendrogram depicts the genetic relationships among the clones,suggesting a geographic relationship.The results indicate that the RAPD markers permitted the identification of the assayed clones,although they are derived from the same geographic origin. 相似文献
49.
Manuel Toral Ibañez Margarita Caru Miguel A. Herrera Luis Gonzalez Luis M. Martin Jorge Miranda Rafael M. Navarro-Cerrillo 《Journal of Zhejiang University. Science. B》2009,10(2):112-119
A protocol of polymerase chain reaction-random amplified polymorphic DNAs (PCR-RAPDs) was established to analyse the gene
diversity and genotype identification for clones of Sequoia sempervirens (D. Don) Endl. in Chile. Ten (out of 34) clones from introduction trial located in Voipir-Villarrica, Chile, were studied.
The PCR-RAPDs technique and a modified hexadecyltrimethylammonium bromide (CTAB) protocol were used for genomic DNA extraction.
The PCR tests were carried out employing 10-mer random primers. The amplification products were detected by electrophoresis
in agarose gels. Forty nine polymorphic bands were obtained with the selected primers (BG04, BF07, BF12, BF13, and BF14) and
were ordered according to their molecular size. The genetic similarity between samples was calculated by the Jaccard index
and a dendrogram was constructed using a cluster analysis of unweighted pair group method using arithmetic averages (UPGMA).
Of the primers tested, 5 (out of 60) RAPD primers were selected for their reproducibility and high polymorphism. A total of
49 polymorphic RAPD bands were detected out of 252 bands. The genetic similarity analysis demonstrates an extensive genetic
variability between the tested clones and the dendrogram depicts the genetic relationships among the clones, suggesting a
geographic relationship. The results indicate that the RAPD markers permitted the identification of the assayed clones, although
they are derived from the same geographic origin.
Project (No. CONICYT-FONDEF PROYECT D01 I 1008) supported by the National Commission of Science and Research of Chile 相似文献
50.
High-level athletes are accorded deferential treatment by the French state. They enjoy the status of ‘high-performance athletes', which entitles them to assistance from the state and a set of special provisions. This paper provides an overview of the political circumstances in which this status was originated and developed, from its initial recognition under the 1975 Sports Law to the paradoxical social effects that this state policy has had on its beneficiaries: the athletes themselves. The first part of the paper is based largely on a search of parliamentary archives relating to the adoption of this law, known as the Mazeaud law, while the second part is based on a survey and interviews conducted with a number of French athletes who were selected for the 1972 and 1992 Olympic Games in Munich and Barcelona respectively. In addressing these two key phases in the recognition of athlete status, its political development and its subsequent reception, the article illustrates the changes in both status and condition of high-performance athlete, based on very different time scales and inspired by fairly different expectations. Given that the present system aims to improve the position of athletes in terms of their post-competitive lives, the long-term benefit of representing France under these circumstances remains questionable. 相似文献