295 research outputs found
Sperm mobility: mechanisms of fertilizing efficiency, genetic variation and phenotypic relationship with male status in the domestic fowl, Gallus gallus domesticus
When females are sexually promiscuous, sexual selection continues after insemination through sperm
competition and cryptic female choice, and male traits conveying an advantage in competitive fertilization
are selected for. Although individual male and ejaculate traits are known to influence paternity in a competitive
scenario, multiple mechanisms co-occur and interact to determine paternity. The way in which
different traits interact with each other and the mechanisms through which their heritability is maintained
despite selection remain unresolved. In the promiscuous fowl, paternity is determined by the number of
sperm inseminated into a female, which is mediated by male social dominance, and by the quality of the
sperm inseminated, measured as sperm mobility. Here we show that: (i) the number of sperm inseminated
determines how many sperm reach the female sperm-storage sites, and that sperm mobility mediates the
fertilizing efficiency of inseminated sperm, mainly by determining the rate at which sperm are released
from the female storage sites, (ii) like social status, sperm mobility is heritable, and (iii) subdominant
males are significantly more likely to have higher sperm mobility than dominant males. This study indicates
that although the functions of social status and sperm mobility are highly interdependent, the lack of
phenotypic integration of these traits may maintain the variability of male fitness and heritability of fertilizing
efficiency
Reformulating the Schrodinger equation as a Shabat-Zakharov system
We reformulate the second-order Schrodinger equation as a set of two coupled
first order differential equations, a so-called "Shabat-Zakharov system",
(sometimes called a "Zakharov-Shabat" system). There is considerable
flexibility in this approach, and we emphasise the utility of introducing an
"auxiliary condition" or "gauge condition" that is used to cut down the degrees
of freedom. Using this formalism, we derive the explicit (but formal) general
solution to the Schrodinger equation. The general solution depends on three
arbitrarily chosen functions, and a path-ordered exponential matrix. If one
considers path ordering to be an "elementary" process, then this represents
complete quadrature, albeit formal, of the second-order linear ODE.Comment: 18 pages, plain LaTe
Semiclassical wave equation and exactness of the WKB method
The exactness of the semiclassical method for three-dimensional problems in
quantum mechanics is analyzed. The wave equation appropriate in the
quasiclassical region is derived. It is shown that application of the standard
leading-order WKB quantization condition to this equation reproduces exact
energy eigenvalues for all solvable spherically symmetric potentials.Comment: 13 page
A latent trait approach to measuring HIV/AIDS related stigma in healthcare professionals: application of mokken scaling technique
The attitudes of healthcare professionals towards HIV positive patients and high risk groups are central to the quality of care and therefore to the management of HIV/AIDS related stigma in health settings. Extant HIV/AIDS stigma scales that measure stigmatising attitudes towards people living with HIV/AIDS have been developed using scaling techniques such as principal component analysis. This approach has resulted in instruments that are often long. Mokken scale analysis is a nonparametric hierarchical scaling technique that can be used to develop unidimensional cumulative scales. This technique is advantageous over the other approaches; as the scales are usually shorter, while retaining acceptable psychometric properties. Moreover, Mokken scales also make no distributional assumptions about the underlying data, other than that the data are capable of being ordered by item and by person. In this study we aimed at developing a precise and concise measure of HIV/AIDS related stigma among health care professionals, using Mokken scale analysis
Accuracy of Semiclassical Methods for Shape Invariant Potentials
We study the accuracy of several alternative semiclassical methods by
computing analytically the energy levels for many large classes of exactly
solvable shape invariant potentials. For these potentials, the ground state
energies computed via the WKB method typically deviate from the exact results
by about 10%, a recently suggested modification using nonintegral Maslov
indices is substantially better, and the supersymmetric WKB quantization method
gives exact answers for all energy levels.Comment: 7 pages, Latex, and two tables in postscrip
Evaluation of Stepped Care for Chronic Pain (ESCAPE) in Veterans of the Iraq and Afghanistan Conflicts A Randomized Clinical Trial
IMPORTANCE:
Despite the prevalence and the functional, psychological, and economic impact of chronic pain, few intervention studies of treatment of chronic pain in veterans have been performed.
OBJECTIVE:
To determine whether a stepped-care intervention is more effective than usual care, as hypothesized, in reducing pain-related disability, pain interference, and pain severity.
DESIGN, SETTING, AND PARTICIPANTS:
We performed a randomized clinical trial comparing stepped care with usual care for chronic pain. We enrolled 241 veterans from Operation Enduring Freedom, Operation Iraqi Freedom, and Operation New Dawn with chronic (>3 months) and disabling (Roland Morris Disability Scale score, ≥7) musculoskeletal pain of the cervical or lumbar spine or extremities (shoulders, knees, and hips) in the Evaluation of Stepped Care for Chronic Pain (ESCAPE) trial from December 20, 2007, through June 30, 2011. The 9-month follow-up was completed by April 2012. Patients received treatment at a postdeployment clinic and 5 general medicine clinics at a Veterans Affairs medical center.
INTERVENTIONS:
Step 1 included 12 weeks of analgesic treatment and optimization according to an algorithm coupled with pain self-management strategies; step 2, 12 weeks of cognitive behavioral therapy. All intervention aspects were delivered by nurse care managers.
MAIN OUTCOMES AND MEASURES:
Pain-related disability (Roland Morris Disability Scale), pain interference (Brief Pain Inventory), and pain severity (Graded Chronic Pain Scale).
RESULTS:
The primary analysis included 121 patients receiving the stepped-care intervention and 120 patients receiving usual care. At 9 months, the mean decrease from baseline in the Roland Morris Disability Scale score was 1.7 (95% CI, -2.6 to -0.9) points in the usual care group and 3.7 (95% CI, -4.5 to -2.8) points in the intervention group (between-group difference, -1.9 [95% CI, -3.2 to -0.7] points; P=.002). The mean decrease from baseline in the Pain Interference subscale score of the Brief Pain Inventory was 0.9 points in the usual care group and 1.7 points in the intervention group (between-group difference, -0.8 [95% CI, -1.3 to -0.3] points; P=.003). The Graded Chronic Pain Scale severity score was reduced by 4.5 points in the usual care group and 11.1 points in the intervention group (between-group difference, -6.6 [95% CI, -10.5 to -2.7] points; P=.001).
CONCLUSIONS AND RELEVANCE:
A stepped-care intervention that combined analgesics, self-management strategies, and brief cognitive behavioral therapy resulted in statistically significant reductions in pain-related disability, pain interference, and pain severity in veterans with chronic musculoskeletal pain
Competences for democratic culture: An empirical study of an intercultural citizenship project in language pedagogy
This article reports on a pedagogical intervention in foreign language teaching in higher education. It analizes the competences developed by Argentinian and UK-based students as they used Skype to design a leaflet that addressed a real world issue: the Argentinian military dictatorship and its manipulation of the 1978 Football World Cup. The data consists of students’ discussions of this highly disturbing human rights issue. A first level of analysis focused on identifying evidence of competences using the Council of Europe’s conceptual model of ‘competences for democratic culture’ (2016). In a second level of analysis, the data was categorized within the framework of Article 2.2 of the United Nations Declaration on Human Rights Education and Training (2011). This research study provides an empirical test of these two frameworks in the field of language education, an aspect that has not been investigated before. It also contributes to our understanding of the potential of intercultural citizenship projects in achieving the goals of human rights education in foreign language teaching. Results indicate the development of substantial competences for democratic culture defined in the Council of Europe’s model
Sperm design and variation in the New World blackbirds (Icteridae)
Post-copulatory sexual selection (PCSS) is thought to be one of the evolutionary forces responsible for the rapid and divergent evolution of sperm design. However, whereas in some taxa particular sperm traits are positively associated with PCSS, in other taxa, these relationships are negative, and the causes of these different patterns across taxa are poorly understood. In a comparative study using New World blackbirds (Icteridae), we tested whether sperm design was influenced by the level of PCSS and found significant positive associations with the level of PCSS for all sperm components but head length. Additionally, whereas the absolute length of sperm components increased, their variation declined with the intensity of PCSS, indicating stabilizing selection around an optimal sperm design. Given the diversity of, and strong selection on, sperm design, it seems likely that sperm phenotype may influence sperm velocity within species. However, in contrast to other recent studies of passerine birds, but consistent with several other studies, we found no significant link between sperm design and velocity, using four different species that vary both in sperm design and PCSS. Potential reasons for this discrepancy between studies are discussed
Competences for democratic culture: An empirical study of an intercultural citizenship project in language pedagogy
This article reports on a pedagogical intervention in foreign language teaching in higher education. It analizes the competences developed by Argentinian and UK-based students as they used Skype to design a leaflet that addressed a real world issue: the Argentinian military dictatorship and its manipulation of the 1978 Football World Cup. The data consists of students’ discussions of this highly disturbing human rights issue. A first level of analysis focused on identifying evidence of competences using the Council of Europe’s conceptual model of ‘competences for democratic culture’ (2016). In a second level of analysis, the data was categorized within the framework of Article 2.2 of the United Nations Declaration on Human Rights Education and Training (2011). This research study provides an empirical test of these two frameworks in the field of language education, an aspect that has not been investigated before. It also contributes to our understanding of the potential of intercultural citizenship projects in achieving the goals of human rights education in foreign language teaching. Results indicate the development of substantial competences for democratic culture defined in the Council of Europe’s model
Sperm gatekeeping : 3D imaging reveals a constricted entrance to zebra finch sperm storage tubules
Females across many internally fertilizing taxa store sperm, often in specialized storage organs in their reproductive tracts. In birds, several hundred sperm storage tubules exist in the utero-vaginal junction of the oviduct, and there is growing evidence that sperm storage in these tubules is selective. The mechanisms underlying female sperm storage in birds remain unknown because of our limited ability to make three-dimensional, live observations inside the large, muscular avian oviduct. Here, we describe a new application of fluorescence selective plane illumination microscopy to optically section oviduct tissue from zebra finch Taeniopygia guttata females label free by harnessing tissue autofluorescence. Our data provide the first description of the three-dimensional structure of sperm storage organs in any vertebrate to the best of our knowledge and reveal the presence of gate-like constricted openings that may play a role in sperm selection
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