596 research outputs found
Building a Bird: Musculoskeletal Modeling and Simulation of Wing-Assisted Incline Running during Avian Ontogeny
Flapping flight is the most power-demanding mode of locomotion, associated with a suite of anatomical specializations in extant adult birds. In contrast, many developing birds use their forelimbs to negotiate environments long before acquiring “flight adaptations,” recruiting their developing wings to continuously enhance leg performance and, in some cases, fly. How does anatomical development influence these locomotor behaviors? Isolating morphological contributions to wing performance is extremely challenging using purely empirical approaches. However, musculoskeletal modeling and simulation techniques can incorporate empirical data to explicitly examine the functional consequences of changing morphology by manipulating anatomical parameters individually and estimating their effects on locomotion. To assess how ontogenetic changes in anatomy affect locomotor capacity, we combined existing empirical data on muscle morphology, skeletal kinematics, and aerodynamic force production with advanced biomechanical modeling and simulation techniques to analyze the ontogeny of pectoral limb function in a precocial ground bird (Alectoris chukar). Simulations of wing-assisted incline running (WAIR) using these newly developed musculoskeletal models collectively suggest that immature birds have excess muscle capacity and are limited more by feather morphology, possibly because feathers grow more quickly and have a different style of growth than bones and muscles. These results provide critical information about the ontogeny and evolution of avian locomotion by (i) establishing how muscular and aerodynamic forces interface with the skeletal system to generate movement in morphing juvenile birds, and (ii) providing a benchmark to inform biomechanical modeling and simulation of other locomotor behaviors, both across extant species and among extinct theropod dinosaurs
Data Sharing in the Social Sciences
In social science research there is a push towards open research and open data. Open Data implies that researchers make their data available to other researchers so that the data can be
re-used. This Guide describes the requirements and provides researchers with guidance on how and where to share social science research data with focus on the Swiss research environment
Pre-registration and registered reports
Pre-registration and registered reports are increasingly advocated to improve the credibility and rigor of empirical research. Pre-registration and more strongly registered reports are expected to reduce reporting and publication bias because they request researchers to define a detailed research plan before the data are collected and before the research outcome is known. Thereby, confirmatory and exploratory research can clearly be distinguished
Work-Family Arrangement and Conflict: Do Individual Gender Role Attitudes and National Gender Culture Matter?
This article examines the relationship between couples' work-family arrangement and individuals' perceived work–family conflict (WFC), considering individuals’ attitudes towards gender roles and national gender culture in 37 countries (N = 15,114). Previous research has shown that WFC depends on work and family demands and has mostly accounted for absolute time spent in paid and domestic work. We hypothesize that WFC depends on couples' work-family arrangement in terms of time spent in paid, domestic and care work. We further expect that the relationship between couples' work-family arrangement and WFC depends on individuals' gender attitudes and national gender culture. To test these assumptions, we use the ISSP-2012 data and apply multilevel linear regression analyses. The findings indicate that an egalitarian work-family arrangement - that is, sharing paid, domestic and care work equally with one's partner - is associated with lower levels of WFC. Moreover, individuals with egalitarian gender attitudes and an egalitarian work-family arrangement experience less WFC than individuals with inconsistent attitudes and behaviours. Individuals with consistent traditional attitudes and behaviours experience the most conflict. Finally, a more egalitarian gender culture relates to less WFC. Cross-level interactions indicate that the relationship between work-family arrangement and WFC is not mediated by countries' gender culture
Spin-flip hot spots in ultrathin films of monovalent metals: Enhancement and anisotropy of the Elliott-Yafet parameter
In contrast to the long-known fact that spin-flip hot spots, i.e., special
\vc{k}-points on the Fermi surface showing a high spin-mixing parameter, do not
occur in the bulk of monovalent (noble and alkali) metals, we found them on the
surface Brillouin-zone boundary of ultrathin films of these metals.
Density-functional calculations within the Korringa-Kohn-Rostoker Green
function method for ultrathin (001) oriented Cu, Ag, and Au films of 10-layer
thickness show that the region around the hot spots can have a substantial
contribution, e.g.\ 52\% in Au(001), to the integrated spin-mixing parameter,
that could lead to a significant enhancement of the spin-relaxation rate or
spin-Hall angle in thin films. Owing to the appearance of spin-flip hot-spots,
a large anisotropy of the Elliott-Yafet parameter [50\% for Au(001)] is also
found in these systems. The findings are important for spintronics applications
in which noble-metals are frequently used and in which the dimensionality of
the sample is reduced.Comment: 6 pages, 2 figure
Lifetime reduction of surface states at Cu, Ag and Au(111) caused by impurity scattering
We present density-functional results on the lifetime of the (111) surface
state of the noble metals. We consider scattering on the Fermi surface caused
by impurity atoms belonging to the 3d and 4sp series. The results are analyzed
with respect to film thickness and with respect to separation of scattering
into bulk or into surface states. While for impurities in the surface layer the
overall trends are similar to the long-known bulk-state scattering, for
adatom-induced scattering we find a surprising behavior with respect to the
adatom atomic number. A plateau emerges in the scattering rate of the 3d
adatoms, instead of a peak characteristic of the d resonance. Additionally, the
scattering rate of 4sp adatoms changes in a zig-zag pattern, contrary to a
smooth parabolic increase following Linde's rule that is observed in bulk. We
interpret these results in terms of the weaker charge-screening and of
interference effects induced by the lowering of symmetry at the surface
Community Schools Unfolded: A review of the literature.
Community schools are quickly increasing in number, but there is no evidence whether they are more effective than traditional schools. No study has empirically compared community schools to other schools. This study reviews the literature on the effectiveness of community schools. We focus on their three main components: cooperation with external organizations, parental involvement, and extracurricular activities. This review indicates that involving external organizations seems valuable in terms of social cohesion in neighborhoods. Parental involvement is particularly important for the educational development of lower socio-economic status families. Extracurricular activities positively relate to students? development in academic and social terms.
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