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排序方式: 共有196条查询结果,搜索用时 78 毫秒
21.
Reduction of water evaporation in polymerase chain reaction microfluidic devices based on oscillating-flow 总被引:1,自引:0,他引:1
Alessandro Polini Elisa Mele Anna Giovanna Sciancalepore Salvatore Girardo Adriana Biasco Andrea Camposeo Roberto Cingolani David A. Weitz Dario Pisignano 《Biomicrofluidics》2010,4(3)
Producing polymeric or hybrid microfluidic devices operating at high temperatures with reduced or no water evaporation is a challenge for many on-chip applications including polymerase chain reaction (PCR). We study sample evaporation in polymeric and hybrid devices, realized by glass microchannels for avoiding water diffusion toward the elastomer used for chip fabrication. The method dramatically reduces water evaporation in PCR devices that are found to exhibit optimal stability and effective operation under oscillating-flow. This approach maintains the flexibility, ease of fabrication, and low cost of disposable chips, and can be extended to other high-temperature microfluidic biochemical reactors. 相似文献
22.
Knee injuries such as anterior cruciate ligament lesions and patellar tendonitis are very frequent in volleyball, and are often attributed to micro traumas that occur during the landing phase of airborne actions. The aim of the present study was to compare different jumping activities during official men's and women's volleyball games. Twelve top-level matches from the Italian men's and women's professional leagues were analysed. The jumps performed during the games were classified according to the landing technique used by the player (left or right foot or both feet together), court position, and ball trajectory. Chi-square analyses were performed to detect differences in landing techniques between the sexes, court positions, and trajectories when serving, attacking, blocking, and setting. Significant differences (P?0.05) were found between the sexes for block, set, and spike but not for the jump serve. The frequency of landings on one foot was related to court position and the trajectory of the sets: when spiking faster sets, the players were more likely to use a one-footed landing. The present results should help coaches and physiotherapists to devise appropriate training and prevention programmes, and reveal the need for further detailed biomechanical investigations of the relationships between landings and knee injuries. 相似文献
23.
Roberto Santana 《Performance Improvement》2010,49(7):25-32
Continuous improvement initiatives are of increasing importance due to the high operating risks of engineering, procurement, and construction management (EPCM) firms in the oil and gas sector ($188 billion worth of oil and gas projects in 2008). This article describes a continuous improvement framework that translates performance problems into an action plan and helps to prevent their recurrence. 相似文献
24.
Leonardo S. Fortes José R. A. Nascimento-Júnior Arnaldo L. Mortatti Dalton Roberto Alvas Araújo de Lima-Júnior Maria E. C. Ferreira 《Research quarterly for exercise and sport》2018,89(3):332-339
It seems that dehydration may impair decision-making performance in athletes. Purpose: This study aimed to investigate the influence of dehydration on passing decision-making performance in soccer players. Method: Participants were 40 male soccer players (Mage = 22.3 ± 2.3 years) who agreed to participate in the study and were randomly assigned to the following conditions: control (CON), dehydration (DEH), and euhydration (EUH). The players played in 2 games of 90 min in duration (2 45-min halves) followed by 2 15-min halves (overtime) with and without proper hydration. The Game Performance Assessment Instrument (GPAI) was considered for the analysis of passing decision making. Results: The GPAI analysis indicated effective reduction in the decision-making index in the DEH condition compared with the EUH and CON conditions, F(2, 38) = 31.4, p < .05, ES = 0.8. Conclusions: In conclusion, dehydration may be considered a mediating factor in the passing decision-making performance of male soccer athletes. 相似文献
25.
This paper provides an overview of the knowledge management systems (KMSs) adopted by small and medium enterprises (SMEs). KMSs are divided into two categories: knowledge management tools (KM-Tools) and knowledge management practices (KM-Practices). On the basis of the analysis of the literature, two research questions (RQs) were identified and addressed through semi-structured interviews carried out in a sample of 35 SMEs operating in high-tech industries. The first RQ concerns the degree of adoption of KMSs by SMEs. The second RQ regards the relationship between KM-Tools and KM-Practices. As far as the degree of adoption of KMSs, the paper highlights that SMEs are not a homogeneous world but there are a variety of approaches and behaviours. As far as the relationship between the degree of adoption of KM-Tools and KM-Practices, the paper identifies three groups of SMEs that seem to point out the stages of the process of adoption of KMSs: Introduction, SMEs that deal with the process of knowledge management exploiting practices and tools that are already known; Growth, SMEs that adopt specialist practices of knowledge management acquiring new organisational and managerial competence in the field of knowledge management; Maturity, SMEs that invest in new technology and that acquire new technological competence in the field of knowledge management. This categorisation paves the way for further theoretical and practical implications for both managers and policy makers. 相似文献
26.
Paulo S. Roberto Amorim Andrew Hills Nuala Byrne 《Research quarterly for exercise and sport》2013,84(2):380-385
Abstract Eighty-two male college students were divided into three equal-size groups for the purpose of testing the transfer effects between motor skills judged similar in perceptual components but different in motor components. Criterion measures of gross movement ability and static balance were analyzed and practice tasks similar to these criterion measures in perceptual components but different in motor components were developed. All subjects were pretested on the criterion measures, after which groups 1 and 2 practiced 3 min. per day for 28 days on the practice tasks while group 3 performed unrelated isometric exercises. On the post-test, the experimental groups were found to be significantly superior to the control group on gross movement accuracy and static balance. It was implied that the transfer resulted from the similarity in perceptual components of the two motor skills, and that perceptual abilities were subject to improvement through practice. 相似文献
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29.
Thaís Cyrino de Mello Forato Roberto de Andrade Martins Maurício Pietrocola 《Science & Education》2012,21(5):657-682
This article presents the main results of a research examining the didactic transposition of history and philosophy of science
in high school level. The adaptation of history of science to this particular level, addressing some aspects of the nature
of science aiming at the students’ critical engagement, was analyzed by examining both the historiographic requirements of
history of science and the pedagogical recommendations of science teaching. The research included the elaboration of a pilot
course on the history of optics, with historical texts and educational activities, and its application in a high school. We
used three episodes of the history of optics, addressing some epistemological points, especially criticizing the naive empirical-inductive
view of science. It was possible to identify a series of obstacles in using history of science and conveying philosophical
views. Their analysis resulted in devising strategies to surmount or to circumvent them. We implemented those strategies in
the classroom and analyzed the data that was obtained. As a result, we substantiated several of our proposals and found that
some solutions require improvement. We suggest some generalizations, which can be understood as initial parameters for guiding
the use of history and philosophy of science in science teaching. We used a qualitative methodology of educational research
to plan, to collect and to analyze the data, examining the interaction between students, teacher and knowledge. 相似文献
30.
Anthony Roberto Gary Meyer Amy Janan Johnson Charles Atkin Patricia Smith 《Journal of Applied Communication Research》2013,41(3):210-230
A radio public service announcement (PSA) focusing on the danger to children from an unlocked and loaded gun was designed and aired 340 times on three radio stations in one Michigan county. At the end of the message, individuals were given a toll-free number to call to receive a free gun trigger-lock. Three surveys were used to assess the effectiveness of this intervention: a general population telephone survey, an automated telephone survey, and a follow-up mail survey. Approximately 20 percent of individuals in the general population heard the PSA. There was a significant increase in uncued knowledge of the locking-related gun-safety practices in the treatment county between time one and time two. Further, individuals in both counties had very high levels of self-efficacy and response efficacy, moderate levels of perceived severity, and very low levels of perceived susceptibility at both points in time. Seven-hundred and ninety-nine individuals called the toll-free number to receive a free gun trigger-lock; or approximately 17 percent of gun-owning households exposed to the message. The majority of callers were males who owned guns primarily for hunting purposes and who planned to use the lock themselves. Follow-up survey results indicated that individuals were using the gun trigger-locks, and that they believed using gun trigger-locks was an easy and effective way to prevent gun injuries. Insights and practical implications of these findings are discussed. 相似文献