Musculoskeletal stiffness during hopping and running does not change following downhill backwards walking     

Corey W. Joseph  Elizabeth J. Bradshaw  Justin Kemp  Ross A. Clark 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(3):241-258

Eccentric contractions that provide spring energy can also cause muscle damage. The aim of this study was to explore leg and vertical stiffness following muscle damage induced by an eccentric exercise protocol. Twenty active males completed 60 minutes of backward-walking on a treadmill at 0.67 m/s and a gradient of ? 8.5° to induce muscle damage. Tests were performed immediately before; immediately post; and 24, 48, and 168 hours post eccentric exercise. Tests included running at 3.35 m/s and hopping at 2.2 Hz using single- and double-legged actions. Leg and vertical stiffness were measured from kinetic and kinematic data, and electromyography (EMG) of five muscles of the preferred limb were recorded during hopping. Increases in pain scores (over 37%) occurred post-exercise and 24 and 48 hours later (p < 0.001). A 7% decrease in maximal voluntary contraction occurred immediately post-exercise (p = 0.019). Changes in knee kinematics during single-legged hopping were observed 168 hours post (p < 0.05). No significant changes were observed in EMG, creatine kinase activity, leg, or vertical stiffness. Results indicate that knee mechanics may be altered to maintain consistent levels of leg and vertical stiffness when eccentric exercise-induced muscle damage is present in the lower legs.  相似文献   

An Analysis of the Myth of Cultural Equivalence     

John Lange 《Academic Questions》2010,23(3):339-347

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THE ORGANIZATION AND ADMINISTRATION OF SCHOOLS IN CLASSICAL JUDAISM     

Justin Hoffman 《Religious education (Chicago, Ill.)》2013,108(3):416-434

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A Criterion-Referenced Approach to Student Ratings of Instruction     

J. Patrick Meyer  Justin B. Doromal  Xiaoxin Wei  Shi Zhu 《Research in higher education》2017,58(5):545-567

We developed a criterion-referenced student rating of instruction (SRI) to facilitate formative assessment of teaching. It involves four dimensions of teaching quality that are grounded in current instructional design principles: Organization and structure, Assessment and feedback, Personal interactions, and Academic rigor. Using item response theory and Wright mapping methods, we describe teaching characteristics at various points along the latent continuum for each scale. These maps enable criterion-referenced score interpretation by making an explicit connection between test performance and the theoretical framework. We explain the way our Wright maps can be used to enhance an instructor’s ability to interpret scores and identify ways to refine teaching. Although our work is aimed at improving score interpretation, a criterion-referenced test is not immune to factors that may bias test scores. The literature on SRIs is filled with research on factors unrelated to teaching that may bias scores. Therefore, we also used multilevel models to evaluate the extent to which student and course characteristic may affect scores and compromise score interpretation. Results indicated that student anger and the interaction between student gender and instructor gender are significant effects that account for a small amount of variance in SRI scores. All things considered, our criterion-referenced approach to SRIs is a viable way to describe teaching quality and help instructors refine pedagogy and facilitate course development.  相似文献   

Electrical lysis of cells for detergent-free droplet assays     

N. de Lange  T. M. Tran  A. R. Abate 《Biomicrofluidics》2016,10(2)

Efficient lysis is critical when analyzing single cells in microfluidic droplets, but existing methods utilize detergents that can interfere with the assays to be performed. We demonstrate robust cell lysis without the use of detergents or other chemicals. In our method, cells are exposed to electric field immediately before encapsulation in droplets, resulting in cell lysis. We characterize lysis efficiency as a function of control parameters and demonstrate compatibility with enzymatic assays by measuring the catalysis of β-glucosidase, an important cellulase used in the conversion of biomass to biofuel. Our method enables assays in microfluidic droplets that are incompatible with detergents.  相似文献   

Impaired acuity of the approximate number system underlies mathematical learning disability (dyscalculia)     

Mazzocco MM  Feigenson L  Halberda J 《Child development》2011,82(4):1224-1237

Many children have significant mathematical learning disabilities (MLD, or dyscalculia) despite adequate schooling. The current study hypothesizes that MLD partly results from a deficiency in the Approximate Number System (ANS) that supports nonverbal numerical representations across species and throughout development. In this study of 71 ninth graders, it is shown that students with MLD have significantly poorer ANS precision than students in all other mathematics achievement groups (low, typically, and high achieving), as measured by psychophysical assessments of ANS acuity (w) and of the mappings between ANS representations and number words (cv). This relation persists even when controlling for domain-general abilities. Furthermore, this ANS precision does not differentiate low-achieving from typically achieving students, suggesting an ANS deficit that is specific to MLD.  相似文献   

传统制造业集群协同演进机制探析——天津自行车集群纵向案例研究     

张红娟  谭劲松 《科学学与科学技术管理》2011,32(4)

产业集群对区域乃至国家经济发展具有重要的作用,然而产业集群发展过程中的影响因素及其相互作用机制至今仍未得到系统的阐述.从协同演进理论视角,结合组织生态学、制度理论、战略管理理论和社会网络理论等,对天津自行车产业集群的发展历程展开多层次、时间序列的分析,以深入挖掘产业集群发展过程中各种要素的相互作用、协同演进机制,提出产业集群的发展是企业战略、产业环境以及制度环境协同演进的过程,同时集群发展过程中创业者的社会资本发挥重要作用.这种将多维理论视角相结合起来进行分析的方法,有利于更好地理解产业集群的演进机制.  相似文献   

Beginning Science Teachers’ Use of a Digital Video Annotation Tool to Promote Reflective Practices     

Justin McFadden  Joshua Ellis  Tasneem Anwar  Gillian Roehrig 《Journal of Science Education and Technology》2014,23(3):458-470

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Benzodiazepine administration prevents the use of error-correction mechanisms during fear extinction     

Genevra Hart  Nathan M. Holmes  Justin A. Harris  R. Frederick Westbrook 《Learning & behavior》2014,42(4):383-397

Three experiments examined the effect of systemic administration of the benzodiazepine midazolam on extinction and re-extinction of conditioned fear. Experiment 1 demonstrated that midazolam administration prior to extinction of a conditioned stimulus (CS) impaired that extinction when rats were subsequently tested drug free; however, extinction was spared if rats were extinguished, reconditioned, and re-extinguished under midazolam. Experiment 2 provided a replication of this effect within-subjects; rats were conditioned to two CSs (A and B), extinguished to one (A-), reconditioned to both, and then extinguished/re-extinguished to both stimuli in compound (AB-), under either vehicle or midazolam. On the drug-free test, rats given midazolam froze more to the CS that had been extinguished (B) than the one that been re-extinguished (A). The final experiment examined whether extinction under midazolam was regulated by prediction error. Rats were trained with three CSs (A, B, C) and extinguished to two (A-, C-). These stimuli then underwent additional extinction under midazolam or vehicle, with one CS now presented in compound with the non-extinguished CS (AB-, C-). Rats were then tested for fear of A relative to C. Rats given vehicle showed a deepening of extinction to A relative to C, as is predicted from error-correction models; however, rats given midazolam failed to show any such discrepancy in responding. The results are interpreted to indicate that the drug reduced prediction error during extinction by reducing fear, and rats were able to re-extinguish fear via a retrieval mechanism that is independent of prediction error.  相似文献   

A simultaneous model of nonprofit symphony orchestra behavior     

William A. Luksetich  Mark D. Lange 《Journal of Cultural Economics》1995,19(1):49-68

In this paper, we test a six equation simultaneous model of nonprofit symphony orchestra behavior. The model is based on Hansmann's theory of nonprofit behavior in the performing arts. The results show that the most prestigious of the orchestras practise a pricing policy that encourages patrons to make a tax deductible contribution. In this manner, they achieve a pattern of price discrimination that, instead of increasing revenues, reduces revenues. Following conditions suggested by Hansmann, we are also able to draw conclusions about the objectives of nonprofit symphony orchestras.  相似文献