361 research outputs found
Entanglement fidelity for electron-electron interaction in strongly coupled semiclassical plasma and under external fields
This paper presents the effects of AB-flux field and electric field on
electron-electron interaction, encircled by a strongly coupled semiclassical
plasma. We found that weak external fields are required to perpetuate a
low-energy elastic electron-electron interaction in a strongly coupled
semiclassical plasma. The entanglement fidelity in the interaction process has
been examined. We have used partial wave analysis to derive the entanglement
fidelity. We found that for a weak electric field, the fidelity ratio for
electron-electron interaction increase as projectile energy increase but
remains constant or almost zero for a strong electric field. Our results
provide an invaluable information on how the efficiency of entanglement
fidelity for a low-energy elastic electron-electron interaction in a strongly
coupled semiclassical plasma can be influenced by the presence of external
fields
{\kappa} state solutions for the fermionic massive spin-1/2 particles interacting with double ring-shaped Kratzer and oscillator potentials
In recent years, an extensive survey on various wave equations of
relativistic quantum mechanics with different types of potential interactions
has been a line of great interest. In this regime, special attention has been
given to the Dirac equation because the spin-1/2 fermions represent the most
frequent building blocks of the molecules and atoms. Motivated by the
considerable interest in this equation and its relativistic symmetries (spin
and pseudospin) in the presence of solvable potential model, we attempt to
obtain the relativistic bound states solution of the Dirac equation with double
ring-shaped Kratzer and oscillator potentials under the condition of spin and
pseudospin symmetries. The solutions are reported for arbitrary quantum number
in a compact form. the analytic bound state energy eigenvalues and the
associated upper- and lower-spinor components of two Dirac particles have been
found. Several typical numerical results of the relativistic eigenenergies have
also been presented. We found that the existence or absence of the ring shaped
potential potential has strong effects on the eigenstates of the Kratzer and
oscillator particles with a wide band spectrum except for the
pseudospin-oscillator particles where there exist a narrow band gap.Comment: 27 pages, 1 figur
Curricular Satisfaction Levels of National Athletic Trainers\u27 Association- Accredited Postprofessional Athletic Training Graduates
Context: Academic programs rely on outcomes assessments to determine if changes in the curriculum are necessary. Objective: To examine the overall satisfaction levels of graduates (2005-2006) of National Athletic Trainers\u27 Association-accredited postprofessional athletic training education programs as related to the 2002 Standards and Guidelines for Development and Implementation of NATA-Accredited PostProfessional Graduate Athletic Training Education Programs. Design: Original survey instrument and demographic questionnaire. Setting: Online survey instrument. Patients or Other Participants: Of 211 survey recipients, 123 returned surveys (58.29% response rate). Main Outcome Measure(s): Demographic information and satisfaction levels in 10 standard areas (depth of learning, breadth of learning, critical thinking, instructor availability, theoretic basis, writing skills, scholarly growth, community return, leadership, and overall program satisfaction) were obtained. Satisfaction scores were categorized into 10 percentage brackets (eg, 80%-89%) for each standard area. Results: No differences were noted in relation to any of the standard satisfaction areas for evaluation of time off from school. However, graduates who required more than the allotted amount of time to complete their degree were less satisfied in the areas of depth of learning (P = .027), breadth of learning (P = .001), instructor availability (P = .005), writing (P = .022), and overall program satisfaction (P = .016). Conclusions: Graduates were generally satisfied across all areas of their didactic curriculum. However, satisfaction levels were affected if graduates required more than the allotted amount of time to complete their degrees
Inter-Rater Agreement and Validity of a Tackling Performance Assessment Scale in Youth American Football
Background: Long term neurologic injury and concussion have been identified as risks from participation in American football. Altering tackling form has been recommended to reduce the risk of neurologic injury caused by head accelerations when tackling. The purpose of this research is to determine the inter-rater agreement and validity of the Qualitative Youth Tackling System (QYTS), a six-item feedback scale to correct tackling form, when utilized by novice and expert raters.
Hypothesis: Experienced raters will have higher levels of agreement with each other and with motion capture when compared to novice raters. Methods: Both novice and experienced raters viewed video of youth athletes (ages 9-13) tackling a dummy in a laboratory setting along. The raters identified successful performance according to a binary rating scale for each component. Analysis of both the raters\u27 agreement with each other and with an objective motion capture measure were completed.
Results: Fliess\u27 Kappa measures between all raters were found to be moderate for head placement (k=.48), fair for cervical extension (k=.38), trunk inclination (k=.37), shoulder extension (k=.27) and step length (k=.29), and there was no agreement for pelvic height (k=.-16). When compared to the dichotomized validation measures of each of the five components provided by the motion capture system the average Cohen\u27s Kappa agreement was substantial for pelvic height (k=.63), fair for step length (k=.34), cervical extension (k=.40), trunk inclination (k=.35), and slight for shoulder extension (k=.16). The experienced raters out-performed the novice raters in all categories.
Conclusion: The results of this study indicate that skilled raters are better able to identify the movement patterns included in the QYTS when compared to a validation measure as well have higher rates of interrater agreement than novice raters.
Level of Evidence: 3
The Effect of Tackling Training on Head Accelerations in Youth American Football
Background: Many organizations have introduced frameworks to reduce the incidence of football related concussions through proper equipment fitting, coach education, and alteration of tackling technique.
Purpose: The purpose of this study was to examine the effects of training in a vertical, head up tackling style on the number of head accelerations experienced while tackling in a controlled laboratory situation. The authors hypothesized that training in a head up tackling technique would reduce the severity of head acceleration experienced by participants.
Design: Controlled Laboratory Study.
Methods: Twenty-four participants (11.5 ± 0.6 years old, 60.5 ± 2.2 in, 110 ± 18.4 lbs.) with previous playing experience completed a one-day training session on tackling technique utilizing a tackling dummy. A subgroup of these participants completed an additional two days of training with a 48 hour retention test. Head accelerations were analyzed at baseline and end of training. Feedback consisted of verbal feedback utilizing the Qualitative Youth Tackling Scale (QYTS) and video tackling playback.
Results: A significant reduction in the number of peak linear head accelerations over 10 g and peak rotational head accelerations over 1885 deg/s² were found in dummy tackling after training in both the one day and three day training regimens. A significant change in QYTS tackling form score was found between pretest and post-test (p=0.004). Participants with larger steps had a 2.28, 4.42 and 4.14 increased odds ratio of sustaining head accelerations over 10, 15 and 20 g respectively.
Conclusions: Training in a vertical, head up tackling style decreased the number of head accelerations over threshold values sustained while tackling; decreased step length may be the driving factor in the effectiveness of this tackling form.
Level of Evidence: Level 3
New Perspectives for Watering Substrate-Based Root Modules in Microgravity in the Advanced Plant Habitat (APH)
No abstract availabl
Molecular analysis of axonal-intrinsic and glial-associated co-regulation of axon degeneration
Organization of sensorimotor activity in anterior cruciate ligament reconstructed individuals: an fMRI conjunction analysis
IntroductionAnterior cruciate ligament reconstruction (ACLR) is characterized by persistent involved limb functional deficits that persist for years despite rehabilitation. Previous research provides evidence of both peripheral and central nervous system adaptations following ACLR. However, no study has compared functional organization of the brain for involved limb motor control relative to the uninvolved limb and healthy controls. The purpose of this study was to examine sensorimotor cortex and cerebellar functional activity overlap and non-overlap during a knee motor control task between groups (ACLR and control), and to determine cortical organization of involved and uninvolved limb movement between groups.MethodsEighteen participants with left knee ACLR and 18 control participants performed a knee flexion/extension motor control task during functional magnetic resonance imaging (fMRI). A conjunction analysis was conducted to determine the degree of overlap in brain activity for involved and uninvolved limb knee motor control between groups.ResultsThe ACLR group had a statistically higher mean percent signal change in the sensorimotor cortex for the involved > uninvolved contrast compared to the control group. Brain activity between groups statistically overlapped in sensorimotor regions of the cortex and cerebellum for both group contrasts: involved > uninvolved and uninvolved > involved. Relative to the control group, the ACLR group uniquely activated superior parietal regions (precuneus, lateral occipital cortex) for involved limb motor control. Additionally, for involved limb motor control, the ACLR group displayed a medial and superior shift in peak voxel location in frontal regions; for parietal regions, the ACLR group had a more posterior and superior peak voxel location relative to the control group.ConclusionACLR may result in unique activation of the sensorimotor cortex via a cortically driven sensory integration strategy to maintain involved limb motor control. The ACLR group's unique brain activity was independent of strength, self-reported knee function, and time from surgery
Recommended from our members
A review on approaches to solving Poisson’s equation in projection-based meshless methods for modelling strongly nonlinear water waves
Three meshless methods, including incompressible smooth particle hydrodynamic (ISPH), moving particle semi-implicit (MPS) and meshless local Petrov–Galerkin method based on Rankine source solution (MLPG_R) methods, are often employed to model nonlinear or violent water waves and their interaction with marine structures. They are all based on the projection procedure, in which solving Poisson’s equation about pressure at each time step is a major task. There are three different approaches to solving Poisson’s equation, i.e. (1) discretizing Laplacian directly by approximating the second-order derivatives, (2) transferring Poisson’s equation into a weak form containing only gradient of pressure and (3) transferring Poisson’s equation into a weak form that does not contain any derivatives of functions to be solved. The first approach is often adopted in ISPH and MPS, while the third one is implemented by the MLPG_R method. This paper attempts to review the most popular, though not all, approaches available in literature for solving the equation
ACL injury prevention, more effective with a different way of motor learning?
What happens to the transference of learning proper jump-landing technique in isolation when an individual is expected to perform at a competitive level yet tries to maintain proper jump-landing technique? This is the key question for researchers, physical therapists, athletic trainers and coaches involved in ACL injury prevention in athletes. The need for ACL injury prevention is clear, however, in spite of these ongoing initiatives and reported early successes, ACL injury rates and the associated gender disparity have not diminished. One problem could be the difficulties with the measurements of injury rates and the difficulties with the implementation of thorough large scale injury prevention programs. A second issue could be the transition from conscious awareness during training sessions on technique in the laboratory to unexpected and automatic movements during a training or game involves complicated motor control adaptations. The purpose of this paper is to highlight the issue of motor learning in relation to ACL injury prevention and to post suggestions for future research. ACL injury prevention programs addressing explicit rules regarding desired landing positions by emphasizing proper alignment of the hip, knee, and ankle are reported in the literature. This may very well be a sensible way, but the use of explicit strategies may be less suitable for the acquisition of the control of complex motor skills (Maxwell et al. J Sports Sci 18:111-120, 2000). Sufficient literature on motor learning and it variations point in that direction
- …