396 research outputs found
Synthesis and Magnetic Properties of Cobalt Ferrite (CoFe2O4) Nanoparticles Prepared by Wet Chemical Route
Magnetic nanoparticles of cobalt ferrite have been synthesized by wet
chemical method using stable ferric and cobalt salts with oleic acid as the
surfactant. X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM)
confirmed the formation of single phase cobalt ferrite nanoparticles in the
range 15-48nm depending on the annealing temperature and time. The size of the
particles increases with annealing temperature and time while the coercivity
goes through a maximum, peaking at around 28nm. A very large coercivity
(10.5kOe) is observed on cooling down to 77K while typical blocking effects are
observed below about 260K. The high field moment is observed to be small for
smaller particles and approaches the bulk value for large particles.Comment: 18 pages, accepted in JMMM, (May, 2006
Magnetic response of core-shell cobalt ferrite nanoparticles at low temperature
Cobaltferritenanoparticles (size: 26±4nm) have been synthesized by coprecipitation route. The coercivity of nanoparticles follows a simple model of thermal activation of particle moments over the anisotropy barrier in the temperature range of 30–300K in accordance with Kneller’s law; however, at low temperatures
Employing an operator form of the Rodrigues formula to calculate wavefunctions without differential equations
The factorization method of Schrodinger shows us how to determine the energy
eigenstates without needing to determine the wavefunctions in position or
momentum space. A strategy to convert the energy eigenstates to wavefunctions
is well known for the one-dimensional simple harmonic oscillator by employing
the Rodrigues formula for the Hermite polynomials in position or momentum
space. In this work, we illustrate how to generalize this approach in a
representation-independent fashion to find the wavefunctions of other problems
in quantum mechanics that can be solved by the factorization method. We examine
three problems in detail: (i) the one-dimensional simple harmonic oscillator;
(ii) the three-dimensional isotropic harmonic oscillator; and (iii) the
three-dimensional Coulomb problem. This approach can be used in either
undergraduate or graduate classes in quantum mechanics.Comment: (10 pages, 1 figure, plus supplemental material
Exchange Bias and Vertical Shift in CoFe2O4 nanoparticles
Magnetic properties of core-shell cobalt ferrite nanoparticles 15 to 48nm
prepared by a sol-gel route have been studied. It is shown that the coercivity
follows non-monotonic size dependence varying as 1/d above the maximum (d is
the particle size). Field cooled magnetization exhibited both horizontal
(exchange bias) and vertical shifts. The exchange bias is understood as
originating at the interface between a surface region with structural and spin
disorder and a core ferrimagnetic region. The dependence of the exchange bias
and vertical shifts on the particle sizes and cooling fields are found to have
significant differences and the differences are explained in the light of
recent results which suggest that both weakly and strongly pinned spins are
present at the interface. It is suggested that the exchange bias is dominated
by the weakly pinned spins while the vertical shift is affected by the strongly
pinned ones.Comment: 2
Return to Sport After Turf Toe Injuries: A Systematic Review and Meta-analysis
A grant from the One-University Open Access Fund at the University of Kansas was used to defray the author's publication fees in this Open Access journal. The Open Access Fund, administered by librarians from the KU, KU Law, and KUMC libraries, is made possible by contributions from the offices of KU Provost, KU Vice Chancellor for Research & Graduate Studies, and KUMC Vice Chancellor for Research. For more information about the Open Access Fund, please see http://library.kumc.edu/authors-fund.xml.Background:
The prevalence of turf toe injuries has increased in recent years. However, uncertainty remains as to how to optimally treat turf toe injuries and the implications that the severity of the injury has on outcomes, specifically return to sport (RTS).
Purpose:
To determine RTS based on treatment modality and to provide clinicians with additional information when comparing operative versus nonoperative treatment of turf toe injuries in athletes.
Study Design:
Systematic review; Level of evidence, 4.
Methods:
A systematic review and meta-analysis was performed using the PubMed/Ovid MEDLINE/PubMed Central databases (May 1964 to August 2018) per PRISMA-IPD (Preferred Reporting Items for Systematic Reviews and Meta-Analyses of Individual Participant Data) guidelines. RTS, treatment, severity of injury, athletic position, and sport were recorded and analyzed.
Results:
Of 858 identified studies, 12 met the criteria for the final meta-analysis. The studies included 112 athletes sustaining a total of 121 turf toe injuries; 63 (52.1%) of these injuries were treated surgically, while 58 (47.9%) were treated nonoperatively, and 53.7% were classified by the grade of injury (grade I, n = 1; grade II, n = 9; grade III, n = 55). Overall, 56 (46.3%) injuries could not be classified based on the data provided and were excluded from the final analysis. The median time to RTS for patients treated nonoperatively was 5.85 weeks (range, 3.00-8.70 weeks) compared with 14.70 weeks (range, 6.00-156.43 weeks) for patients treated surgically (P < .001); however, there was variability in the grade of injury between the 2 groups. Similarly, patients who sustained grade II injuries returned to sport more quickly (8.70 weeks) than patients who had a grade I (13.04 weeks) or grade III injury (16.50 weeks) (P = .016). The amount of time required to RTS was significantly influenced by the athlete’s level of play (16.50 weeks for both high school and college levels; 14.70 weeks for professional level) (P = .018).
Conclusion:
The time to RTS for an athlete who suffers from a turf toe injury is significantly influenced by the severity of injury and the athlete’s level of competition. Professional athletes who suffer from turf toe injuries RTS sooner than both high school and college athletes. However, there are a limited number of high-level studies evaluating turf toe injuries in the athletic population. Further research is necessary to clearly define the appropriate treatment and RTS protocols based on sport, position, and level of play
Medical students’ preparedness for professional activities in early clerkships
Background Sufficient preparedness is important for transitions to workplace
participation and learning in clinical settings. This study aims to analyse
medical students’ preparedness for early clerkships using a three-dimensional,
socio-cognitive, theory-based model of preparedness anchored in specific
professional activities and their supervision level. Methods Medical students
from a competency-based undergraduate curriculum were surveyed about
preparedness for 21 professional activities and level of perceived supervision
during their early clerkships via an online questionnaire. Preparedness was
operationalized by the three dimensions of confidence to carry out clerkship
activities, being prepared through university teaching and coping with failure
by seeking support. Factors influencing preparedness and perceived stress as
outcomes were analysed through step-wise regression. Results Professional
activities carried out by the students (n = 147; 19.0%) and their supervision
levels varied. While most students reported high confidence to perform the
tasks, the activity-specific analysis revealed important gaps in preparation
through university teaching. Students regularly searched for support in case
of difficulty. One quarter of the variance of each preparedness dimension was
explained by self-efficacy, supervision quality, amount of prior clerkship
experience and nature of professional activities. Preparedness contributed to
predicting perceived stress. Conclusions The applied three-dimensional concept
of preparedness and the task-specific approach provided a detailed and
meaningful view on medical students’ workplace participation and experiences
in early clerkships
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