2,273 research outputs found
In Search of Modifiable Risk and Protective Factors for Teen Dating Violence
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137513/1/jora12280_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137513/2/jora12280.pd
Potentiality in Biology
We take the potentialities that are studied in the biological sciences (e.g., totipotency) to be an important subtype of biological dispositions. The goal of this paper is twofold: first, we want to provide a detailed understanding of what biological dispositions are. We claim that two features are essential for dispositions in biology: the importance of the manifestation process and the diversity of conditions that need to be satisfied for the disposition to be manifest. Second, we demonstrate that the concept of a disposition (or potentiality) is a very useful tool for the analysis of the explanatory practice in the biological sciences. On the one hand it allows an in-depth analysis of the nature and diversity of the conditions under which biological systems display specific behaviors. On the other hand the concept of a disposition may serve a unificatory role in the philosophy of the natural sciences since it captures not only the explanatory practice of biology, but of all natural sciences. Towards the end we will briefly come back to the notion of a potentiality in biology
Distancing or drawing together: Sexism and organizational tolerance of sexism impact women’s social relationships at work
This is the final version. Available on open access from Wiley via the DOI in this recordData availability: Data associated with these studies can be viewed at https://osf.io/af95p/?view_only=a9dd26d879834a30bd49652cd4195db0This article examines the role of organisational climate in women's social responses to sexism at work. We argue that after experiences of sexism, women “draw together” with other women when they perceive that the organisational climate is intolerant of sexism. We assess the role of organisational climate at three levels: peer‐, manager‐, and policy‐level. We conducted a correlational study (N study1 = 405) and two experimental studies (N study2 = 377, N study3 = 391), in which we examined women's experiences of sexism at work (measured in Study 1; manipulated in Studies 2 and 3). We also measured perceived tolerance of sexism at the peer‐, manager‐ and policy‐level in all studies. The main DVs were women's workplace friendships with other women in Studies 1 and 2, and closeness to female co‐workers in Study 3. Results showed that perceived tolerance of sexism from peers was especially important in shaping women's social relationships following experiences of sexism; tolerance from managers or at the policy level had less consistent effects. Specifically, experiences with sexism were positively associated with female participants' reported friendship (Studies 1 and 2) and closeness (Study 3) with their female colleagues, but only when peers were perceived not to tolerate sexism. When peers were perceived to tolerate sexism, female participants did not respond to sexism by drawing together.Republic of Turkey, Ministry of National Educatio
Spectroscopic factors for bound s-wave states derived from neutron scattering lengths
A simple and model-independent method is described to derive neutron
single-particle spectroscopic factors of bound s-wave states in nuclei from neutron scattering lengths. Spectroscopic factors
for the nuclei ^{13}C, ^{14}C, ^{16}N, ^{17}O, ^{19}O, ^{23}Ne, ^{37}Ar, and
^{41}Ar are compared to results derived from transfer experiments using the
well-known DWBA analysis and to shell model calculations. The scattering length
of ^{14}C is calculated from the ^{15}C_{g.s.} spectroscopic factor.Comment: 9 pages (uses revtex), no figures, accepted for publication in PRC,
uuencoded tex-files and postscript-files available at
ftp://is1.kph.tuwien.ac.at/pub/ohu/Thermal.u
Staggered Mesh Ewald: An Extension of the Smooth Particle-Mesh Ewald Method Adding Great Versatility
We draw on an old technique for improving the accuracy of mesh-based field calculations to extend the popular Smooth Particle Mesh Ewald (SPME) algorithm as the Staggered Mesh Ewald (StME) algorithm. StME improves the accuracy of computed forces by up to 1.2 orders of magnitude and also reduces the drift in system momentum inherent in the SPME method by averaging the results of two separate reciprocal space calculations. StME can use charge mesh spacings roughly 1.5× larger than SPME to obtain comparable levels of accuracy; the one mesh in an SPME calculation can therefore be replaced with two separate meshes, each less than one third of the original size. Coarsening the charge mesh can be balanced with reductions in the direct space cutoff to optimize performance: the efficiency of StME rivals or exceeds that of SPME calculations with similarly optimized parameters. StME may also offer advantages for parallel molecular dynamics simulations because it permits the use of coarser meshes without requiring higher orders of charge interpolation and also because the two reciprocal space calculations can be run independently if that is most suitable for the machine architecture. We are planning other improvements to the standard SPME algorithm, and anticipate that StME will work synergistically will all of them to dramatically improve the efficiency and parallel scaling of molecular simulations
Design and analysis of low boom concepts at Langley Research Center
The objective of the sonic boom research in the current High Speed Research Program is to ultimately make possible overland supersonic flight by a high speed civil transport. To accomplish this objective, it is felt that results in four areas must demonstrate that such a vehicle would be acceptable by the general public, by the airframers, and by the airlines. It should be demonstrated: (1) that some waveform shape has the possibility of being acceptable to the general public; (2) that the atmosphere would not totally destroy such a waveform during propagation; (3) that a viable airplane could be built which produces such a waveform; and (4) that any performance penalty suffered by a low boom aircraft would be counteracted by the economic benefit of overland supersonic flight. The work being done at LaRC is in support of the third element listed above--the area of configuration design. The initial part of the paper will give a review of the theory being used for configuration designs and discuss two theory validation models which were built and tested within the past two years. Discussion of the wind tunnel and theoretical results (linear theory and higher order methods) and their implications for future designs will be included
Volume-energy correlations in the slow degrees of freedom of computer-simulated phospholipid membranes
Constant-pressure molecular-dynamics simulations of phospholipid membranes in
the fluid phase reveal strong correlations between equilibrium fluctuations of
volume and energy on the nanosecond time-scale. The existence of strong
volume-energy correlations was previously deduced indirectly by Heimburg from
experiments focusing on the phase transition between the fluid and the ordered
gel phases. The correlations, which are reported here for three different
membranes (DMPC, DMPS-Na, and DMPSH), have volume-energy correlation
coefficients ranging from 0.81 to 0.89. The DMPC membrane was studied at two
temperatures showing that the correlation coefficient increases as the phase
transition is approached
Search for flavor-changing neutral currents and lepton-family-number violation in two-body D0 decays
Results of a search for the three neutral charm decays, D0 -> mu e, D0 -> mu
mu, and D0 -> e e, are presented. This study was based on data collected in
Experiment 789 at the Fermi National Accelerator Laboratory using 800 GeV/c
proton-Au and proton-Be interactions. No evidence is found for any of the
decays. Upper limits on the branching ratios, at the 90% confidence level, are
obtained.Comment: 28 pages, 18 figures. Submitted to Physical Review
A Hydrophobic Gate in an Ion Channel: The Closed State of the Nicotinic Acetylcholine Receptor
The nicotinic acetylcholine receptor (nAChR) is the prototypic member of the
`Cys-loop' superfamily of ligand-gated ion channels which mediate synaptic
neurotransmission, and whose other members include receptors for glycine,
gamma-aminobutyric acid, and serotonin. Cryo-electron microscopy has yielded a
three dimensional structure of the nAChR in its closed state. However, the
exact nature and location of the channel gate remains uncertain. Although the
transmembrane pore is constricted close to its center, it is not completely
occluded. Rather, the pore has a central hydrophobic zone of radius about 3 A.
Model calculations suggest that such a constriction may form a hydrophobic
gate, preventing movement of ions through a channel. We present a detailed and
quantitative simulation study of the hydrophobic gating model of the nicotinic
receptor, in order to fully evaluate this hypothesis. We demonstrate that the
hydrophobic constriction of the nAChR pore indeed forms a closed gate.
Potential of mean force (PMF) calculations reveal that the constriction
presents a barrier of height ca. 10 kT to the permeation of sodium ions,
placing an upper bound on the closed channel conductance of 0.3 pS. Thus, a 3 A
radius hydrophobic pore can form a functional barrier to the permeation of a 1
A radius Na+ ion. Using a united atom force field for the protein instead of an
all atom one retains the qualitative features but results in differing
conductances, showing that the PMF is sensitive to the detailed molecular
interactions.Comment: Accepted by Physical Biology; includes a supplement and a
supplementary mpeg movie can be found at
http://sbcb.bioch.ox.ac.uk/oliver/download/Movies/watergate.mp
Coating mechanisms of single-walled carbon nanotube by linear polyether surfactants: insights from computer simulations
The noncovalent coating of carbon-based nanomaterials, such as carbon nanotubes, has important applications in nanotechnology and nanomedicine. The molecular modeling of this process can clarify its mechanism and provide a tool for the design of novel materials. In this paper, the coating mechanism of single-walled carbon nanotubes (SWCNT) in aqueous solutions by 1,2-dimethoxyethane oxide (DME), 1,2-dimethoxypropane oxide (DMP), poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO) pentamers, and L64 triblock copolymer chains have been studied using molecular dynamics (MD) simulations. The results suggest a preferential binding to the SWCNT surface of the DMP molecules with respect to DME mainly driven by their difference in hydrophobicity. For the longer pentamers, it depends by the chain conformation. PPO isomers with radius of gyration larger than PEO pentamers bind more tightly than those with more compact conformation. In the case of the L64 triblock copolymer, the coating of the SWCNT surface produces a shell of PPO blocks with the PEO chains protruding into bulk water as expected from the so-called nonwrapping binding mechanism of SWCNT. In addition, the polymer coating, in qualitative agreement with experimental evidence on the poor capability of the L64 to disperse SWCNT, do not prevent the formation of CNT aggregates
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