The effects of mid-flight whole-body and trunk rotation on landing mechanics: implications for anterior cruciate ligament injuries     

Meghan L. Critchley  Daniel J. Davis  Michaela M. Keener  Jacob S. Layer  Margaret A. Wilson  Qin Zhu 《Sports biomechanics / International Society of Biomechanics in Sports》2020,19(4):421-437

ABSTRACT

The purpose was to quantify the effects of mid-flight whole-body and trunk rotation on knee mechanics in a double-leg landing. Eighteen male and 20 female participants completed a jump-landing-jump task in five conditions: no rotation, testing leg ipsilateral or contralateral (WBRC) to the whole-body rotation direction, and testing leg ipsilateral (TRI) or contralateral to the trunk rotation direction. The WBRC and TRI conditions demonstrated decreased knee flexion and increased knee abduction angles at initial contact (2.6 > Cohen’s dz > 0.3) and increased peak vertical ground reaction forces and knee adduction moments during the 100 ms after landing (1.7 > Cohen’s dz > 0.3). The TRI condition also showed the greatest knee internal rotation angles at initial contact and peak knee abduction and internal rotation angles and peak knee extension moments during the 100 ms after landing (2.0 > Cohen’s dz > 0.5). Whole-body rotation increased contralateral knee loading because of its primary role in decelerating medial-lateral velocities. Trunk rotation resulted in the greatest knee loading for the ipsilateral knee due to weight shifting and mechanical coupling between the trunk and lower extremities. These findings may help understand altered trunk motion in anterior cruciate ligament injuries.  相似文献   

A women's scientific society in the west. The late eighteenth-century assimilation of science     

Jacob MC  Sturkenboom D 《Isis; an international review devoted to the history of science and its cultural influences》2003,94(2):217-252

The Natuurkundig Genootschap der Dames (Women's Society for Natural Knowledge), formally established by and for women, met regularly from 1785 to 1881 and sporadically until 1887. It challenges our stereotypes both of women and the physical sciences during the eighteenth century and of the intellectual interests open to women in the early European republics. This essay aims not simply to identify the society and its members but to describe their pursuits and consider what their story adds to the history of Western science. What does this society's existence tell us about the relationship between women and early science in general and about science and society in the Dutch setting in particular? Science and gender look rather different when observed through the activities of the immensely prosperous women of Middelburg, citizens of one of the most highly literate Western countries. The elite lives of the first-generation members of the women's society also offer us a glimpse into the early domestication of science, a process vital to its acceptance and assimilation.  相似文献   

Government management of two media-facilitated crises involving dioxin contamination of food     

Jacob CJ  Lok C  Morley K  Powell DA 《Public understanding of science (Bristol, England)》2011,20(2):261-269

Incidents become crises through a constant and intense public scrutiny facilitated by the media. Two incidents involving dioxin contamination of food led to crises in Belgium and the Republic of Ireland in 1999 and 2008, respectively. Thought to cause cancer in humans, dioxins reached the food supply in both incidents through the contamination of fat used for animal feed. The food and agricultural industries connected to each incident relied on crisis management activities of federal governments to limit adverse public reaction. Analysis of the management of the two crises by their respective federal governments, and a subsequent review of crisis management literature, led to the development of an effective crisis management model. Such a model, appropriately employed, may insulate industries associated with a crisis against damaged reputations and financial loss.  相似文献   

The Impact of a Professional Development Program on Teachers' Mathematical Knowledge for Teaching,Instruction, and Student Achievement     

Robin Jacob  Heather Hill  Doug Corey 《Journal of research on educational effectiveness》2017,10(2):379-407

In this paper, we describe findings from a three-year evaluation of a well-developed mathematics professional development program that is commercially available on a wide scale. The professional development is designed to improve teachers' mathematical knowledge for teaching and to enable them to elicit more student thinking and reasoning during mathematics lessons. Specifically, it focused on helping teachers (a) learn more mathematics, (b) understand how children learn math, (c) use formative assessment to develop insight into what specific students know and do not know, and (d) develop effective classroom instructional strategies that enable student problem solving. Participants included 105 fourth- and fifth-grade teachers teaching in 19 low-income schools within a single district. Teachers were randomly assigned within schools either to a “business as usual” control group or to receive the professional development. The training consisted of a week-long summer institute and four to six in-service days during the school year. The training was run by full-time trained associates. We find some limited evidence of positive impacts on teachers' mathematical knowledge for teaching, but no effects on instructional practice or student outcomes.  相似文献   

Seeing Merit as a Vehicle for Opportunity and Equity: Youth Respond to School Choice Policy     

Phillippo  Kate  Griffin  Briellen  Del Dotto  B. Jacob  Lennix  Crystal  Tran  Ha 《The Urban Review》2021,53(4):591-616

The Urban Review - School choice policy is ubiquitous in urban school districts. Evidence suggests that it has not fully delivered on its proponents’ promises of equitable educational...  相似文献   

Re-referral to child protective services: the influence of child, family, and case characteristics on risk status   总被引：2，自引：0，他引：2  

Connell CM  Bergeron N  Katz KH  Saunders L  Tebes JK 《Child abuse & neglect》2007,31(5):573-588

INTRODUCTION: This study examines child, family, and case characteristics that impact rates of re-referral to Child Protective Services (CPS) using data on all closed CPS investigations for the state of Rhode Island between 2001 and 2004. METHOD: A longitudinal dataset of all referrals to CPS was created using state submissions to the National Child Abuse and Neglect Data System (NCANDS). After excluding children whose initial CPS investigation resulted in removal from the home, a Cox proportional hazards model was tested to examine factors impacting the likelihood of re-referral. RESULTS: Consistent with other research in this area, the initial 6-month period following case disposition is the period of greatest risk of re-referral. Approximately 13% of cases experienced a recurrent allegation during the first 6-month period; an additional 14% experienced a re-referral over the following 12-month period; 7% during the next 12-month period. Family poverty was the strongest predictor of re-referral, though a number of child and case characteristics were significantly related to recurrence. Cases that were substantiated at index were significantly less likely to result in a new allegation, though substantiated cases of physical abuse or those receiving post-investigation services were at higher risk. CONCLUSIONS: Children from families facing multiple stressors (e.g., low SES, parental substance abuse child disability) are at highest risk of re-referral to CPS and may benefit from the development of preventive services targeted immediately following case closings within CPS.  相似文献   

Zero‐Slack,Noncritical Paths          下载免费PDF全文

Jacob V. Simons Jr. 《Decision Sciences Journal of Innovative Education》2017,15(3):254-267

The critical path method/program evaluation and review technique method of project scheduling is based on the importance of managing a project's critical path(s). Although a critical path is the longest path through a network, its location in large projects is facilitated by the computation of activity slack. However, logical fallacies in oft‐repeated statements of the relationship between slack and the critical path make it easy to overlook the phenomenon of zero‐slack, noncritical paths. This article points out the fallacies and then describes and illustrates the phenomenon. We conclude with teaching recommendations to avoid suboptimal decisions in reducing project duration.  相似文献   

Educational practice,student experience,and the purpose of education—a critique of ‘Pedagogy in Practice’     

Jacob Klitmøller 《牛津教育评论》2016,42(6):646-660

The focus of the present paper is a critical discussion of the recently developed concept Pedagogy in Practice (PiP) with the intention of improving the concept for future research. PiP aims to understand ongoing educational practice from the students’ perspective by interviewing groups of students about their understanding of learning. By emphasising ‘pedagogy’ and ‘practice’ and drawing from a theoretical foundation that takes practice and action as key concepts, PiP is an appealing alternative to research in student voice, to which it is closely related. However, a critical analysis of PiP in relation to its stated theoretical sources (Bourdieu, Bernstein, Dewey) shows that the approach contradicts these sources in key areas. In PiP students’ understanding of learning is taken as basic for improving educational practice, however, PiP is developed without an explicit notion of what education is for. This paper introduces a specific formulation of the purpose and functions of education based on the work of Gert Biesta, and outlines how a revised version of PiP might contribute to future empirical research in education.  相似文献   

Moral Outrage and Musical Corruption: White Educators’ Responses to the “Jazz Problem”     

Jacob Hardesty 《History of education quarterly》2016,56(4):590-617

More than a musical genre, jazz in the 1920s was viewed by critics and supporters alike as a type of lifestyle, one that frequently led to drinking, dancing, and “petting.” Much to the horror of older generations, white young people were particularly drawn to jazz and its “hot rhythms.” Secondary school teachers and administrators took up the formidable task of persuading youth of jazz's morally corrupting influences. I argue that, in the first half of the decade, such educators instituted curricular and various informal policies designed to replace jazz, universally associated with black musicians, with more “wholesome” European‐originated alternatives. By the latter part of the decade, however, most educators admitted a grudging acceptance of jazz's permanence and abandoned their efforts to convince students of its iniquity.  相似文献   

丛林中的守财奴     

Jacob  Wilhelm Grimm  林国 《语数外学习(初中版七年级)》2011,(Z1):86-91

[童话大意]一个农场主有一个忠诚的仆人,这个仆人辛辛苦苦地给他干了三年的活,而他却没有付给仆人任何工钱。后来仆人打定主意,想出去看看外面的世界,不再干下去了。他找到农场主说:"我为你勤勤恳恳地做了这么久的事,相信你会根据我的劳动付给我应得的工钱。"农场主是一个极其吝惜的守财奴,只拿出三便士给他,也就是一年一便士的工钱。可怜的仆人对钱没有多少概念,  相似文献