1,918 research outputs found
Absorption cross sections of minor constituents in planetary atmospheres from 1050 to 2100 angstrom
Absorption cross sections of minor constituent gases in planetary atmospheres from 1050 to 2100
Injury Risk Estimation Expertise: Interdisciplinary Differences in Performance on the ACL Injury Risk Estimation Quiz
Background: Simple observational assessment of movement is a potentially low-cost method for anterior cruciate ligament (ACL)
injury screening and prevention. Although many individuals utilize some form of observational assessment of movement, there are
currently no substantial data on group skill differences in observational screening of ACL injury risk.
Purpose/Hypothesis: The purpose of this study was to compare various groups’ abilities to visually assess ACL injury risk as well
as the associated strategies and ACL knowledge levels. The hypothesis was that sports medicine professionals would perform
better than coaches and exercise science academics/students and that these subgroups would all perform better than parents
and other general population members.
Study Design: Cross-sectional study; Level of evidence, 3.
Methods: A total of 428 individuals, including physicians, physical therapists, athletic trainers, strength and conditioning
coaches, exercise science researchers/students, athletes, parents, and members of the general public participated in the study.
Participants completed the ACL Injury Risk Estimation Quiz (ACL-IQ) and answered questions related to assessment strategy
and ACL knowledge.
Results: Strength and conditioning coaches, athletic trainers, physical therapists, and exercise science students exhibited consistently
superior ACL injury risk estimation ability (þ2 SD) as compared with sport coaches, parents of athletes, and members of
the general public. The performance of a substantial number of individuals in the exercise sciences/sports medicines (approximately
40%) was similar to or exceeded clinical instrument-based biomechanical assessment methods (eg, ACL nomogram).
Parents, sport coaches, and the general public had lower ACL-IQ, likely due to their lower ACL knowledge and to rating the
importance of knee/thigh motion lower and weight and jump height higher.
Conclusion: Substantial cross-professional/group differences in visual ACL injury risk estimation exist. The relatively profound
differences in injury risk estimation accuracy and their potential implications for risk screening suggest the need for additional
training and outreach
Perfect State Transfer in Laplacian Quantum Walk
For a graph and a related symmetric matrix , the continuous-time
quantum walk on relative to is defined as the unitary matrix , where varies over the reals. Perfect state transfer occurs
between vertices and at time if the -entry of
has unit magnitude. This paper studies quantum walks relative to graph
Laplacians. Some main observations include the following closure properties for
perfect state transfer:
(1) If a -vertex graph has perfect state transfer at time relative
to the Laplacian, then so does its complement if is an integer multiple
of . As a corollary, the double cone over any -vertex graph has
perfect state transfer relative to the Laplacian if and only if . This was previously known for a double cone over a clique (S. Bose,
A. Casaccino, S. Mancini, S. Severini, Int. J. Quant. Inf., 7:11, 2009).
(2) If a graph has perfect state transfer at time relative to the
normalized Laplacian, then so does the weak product if for any
normalized Laplacian eigenvalues of and of , we have
is an integer multiple of . As a corollary, a weak
product of with an even clique or an odd cube has perfect state
transfer relative to the normalized Laplacian. It was known earlier that a weak
product of a circulant with odd integer eigenvalues and an even cube or a
Cartesian power of has perfect state transfer relative to the adjacency
matrix.
As for negative results, no path with four vertices or more has antipodal
perfect state transfer relative to the normalized Laplacian. This almost
matches the state of affairs under the adjacency matrix (C. Godsil, Discrete
Math., 312:1, 2011).Comment: 26 pages, 5 figures, 1 tabl
Cross-professional differences in real-time assessment of ACL injury risk
Simple visual inspection of movement is a potentially low cost method for anterior
cruciate ligament (ACL) injury screening and prevention. Although many
professionals, athletes, and coaches utilize some form of visual inspection of
movement/injury risk, there is currently no substantial data on group skill differences.
Sports medicine professionals, exercise science students/academics, and strength
and conditioning coaches exhibited consistently superior ACL injury risk estimation
skill compared to sport coaches, parents of athletes and the general public (about 2
standard deviations). In addition, many individuals’ visual risk assessment accuracy
was similar to or exceeded clinical instrument-based biomechanical assessment
methods (i.e., ACL nomogram). Perceptual-cognitive mechanisms are discussed
Preventing human immunodeficiency virus infection among sexual assault survivors in Cape Town, South Africa: an observational study.
We describe 131 South African sexual assault survivors offered HIV post-exposure prophylaxis (PEP). While the median days completed was 27 (IQR 27, 28), 34% stopped PEP or missed doses. Controlling for baseline symptoms, PEP was not associated with symptoms (OR = 1.30, 95% CI = 0.66, 2.64). Factors associated with unprotected sex included prior unprotected sex (OR = 6.46, 95% CI = 3.04, 13.74), time since the assault (OR = 1.33, 95% CI = 1.12, 1.57) and age (OR = 1.30, 95% CI = 1.08, 1.57). Trauma counseling was protective (OR = 0.18, 95% CI = 0.05, 0.58). Four instances of seroconversion were observed by 6 months (risk = 3.7%, 95% CI = 1.0, 9.1). Proactive follow-up is necessary to increase the likelihood of PEP completion and address the mental health and HIV risk needs of survivors. Adherence interventions and targeted risk reduction counseling should be provided to minimize HIV acquisition
Visual estimation of ACL injury risk: Efficient assessment method, group differences, and expertise mechanisms
Simple observational assessment of movement quality (e.g., drop vertical jump biomechanics) is an efficient and low cost method for anterior cruciate ligament (ACL) injury screening and prevention. A recently developed test (see www.ACL-IQ.org) has revealed substantial cross-professional/group differences in visual ACL injury risk estimation skill. Specifically, parents, sport coaches, and to some degree sports medicine physicians, would likely benefit from training or the use of decision support tools. In addition, expertise mechanisms (perceptual-cognitive characteristics of skilled performers) were investigated in order to design training systems to improve risk estimation performance
Reliability of the tuck jump injury risk screening assessment in elite male youth soccer players
Altered neuromuscular control has been suggested as a mechanism for injury in soccer players. Ligamentous injuries most often occur during dynamic movements, such as decelerations from jump-landing maneuvers where high risk movement patterns are present. The assessment of kinematic variables during jump-landing tasks as part of a pre-participation screen is useful in the identification of injury risk. An example of a field-based screening tool is the repeated tuck jump assessment. The purpose of this study was to analyze the within-subject variation of the tuck jump screening assessment in elite male youth soccer players. 25 pre and 25 post-peak height velocity (PHV) elite male youth soccer players from the academy of a professional English soccer club completed the assessment. A test, re-test design was used to explore the within-subject inter-session reliability. Technique was graded retrospectively against the 10-point criteria set out in the screening protocol using two-dimensional video cameras. The typical error range reported for tuck jump total score (0.90 – 1.01 in pre and post-PHV players respectively) was considered acceptable. When each criteria was analyzed individually, Kappa coefficient determined that knee valgus was the only criterion to reach substantial agreement across the two test sessions for both groups. The results of this study suggest that although tuck jump total score may be reliably assessed in elite male youth soccer players, caution should be applied in solely interpreting the composite score due to the high within-subject variation in a number of the individual criteria. Knee valgus may be reliably used to screen elite youth male soccer players for this plyometric technique error and for test, re-test comparison
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