1,633 research outputs found
Molecular Density Functional Theory of Water describing Hydrophobicity at Short and Long Length Scales
We present an extension of our recently introduced molecular density
functional theory of water [G. Jeanmairet et al., J. Phys. Chem. Lett. 4, 619,
2013] to the solvation of hydrophobic solutes of various sizes, going from
angstroms to nanometers. The theory is based on the quadratic expansion of the
excess free energy in terms of two classical density fields, the particle
density and the multipolar polarization density. Its implementation requires as
input a molecular model of water and three measurable bulk properties, namely
the structure factor and the k-dependent longitudinal and transverse dielectric
susceptibilities. The fine three-dimensional water structure around small
hydrophobic molecules is found to be well reproduced. In contrast the computed
solvation free-energies appear overestimated and do not exhibit the correct
qualitative behavior when the hydrophobic solute is grown in size. These
shortcomings are corrected, in the spirit of the Lum-Chandler-Weeks theory, by
complementing the functional with a truncated hard-sphere functional acting
beyond quadratic order in density. It makes the resulting functional compatible
with the Van-der-Waals theory of liquid-vapor coexistence at long range.
Compared to available molecular simulations, the approach yields reasonable
solvation structure and free energy of hard or soft spheres of increasing size,
with a correct qualitative transition from a volume-driven to a surface-driven
regime at the nanometer scale.Comment: 24 pages, 8 figure
Rituximab therapy for refractory interstitial lung disease related to antisynthetase syndrome
SummaryObjectiveTo report our experience using rituximab as therapy for refractory antisynthetase syndrome (ASS)-associated interstitial lung disease.MethodsWe retrospectively evaluated the medical records of 7 ASS patients with refractory interstitial lung disease, which had previously failed to respond to prednisone and/or other cytotoxic drugs. All 7 patients received rituximab therapy, i.e.: 1 g at days 0 and 14 and at 6-month follow-up. Data on pulmonary symptoms, pulmonary function tests and high resolution computed tomography (HRCT) scan of the lungs were collected: 1) before rituximab initiation; and 2) at 6-month and one-year follow-up after the first infusion of rituximab.ResultsAt one-year follow-up, ASS patients had resolution (n = 2) or improvement of pulmonary clinical manifestations. Patients also exhibited significant improvement of interstitial lung disease parameters: 1) on pulmonary function tests: FVC (p = 0.03) and DLCO (p = 2 × 10−5); 2) and HRCT-scan of the lungs. Due to clinical resolution/improvement of interstitial lung disease, the median daily dose of oral prednisone could be reduced in these 7 ASS patients at one-year follow-up, compared with baseline (20 mg/day vs. 9 mg/day; p = 0.015).ConclusionOur findings suggest that rituximab may be a helpful therapy for refractory interstitial lung disease in patients with ASS
A Spectroscopic Study of Type Ibc Supernova Host Galaxies from Untargeted Surveys
We present the largest spectroscopic study of the host environments of Type
Ibc supernovae (SN Ibc) discovered exclusively by untargeted SN searches. Past
studies of SN Ibc host environments have been biased towards high-mass,
high-metallicity galaxies by focusing on SNe discovered in galaxy-targeted SN
searches. Our new observations more than double the total number of
spectroscopic stellar population age and metallicity measurements published for
untargeted SN Ibc host environments, and extend to a median redshift about
twice as large as previous statistical studies (z = 0.04). For the 12 SNe Ib
and 21 SNe Ic in our metallicity sample, we find median metallicities of
log(O/H)+12 = 8.48 and 8.61, respectively, but determine that the discrepancy
in the full distribution of metallicities is not statistically significant.
This median difference would correspond to only a small difference in the mass
loss via metal-line driven winds (<30%), suggesting this does not play the
dominant role in distinguishing SN Ib and Ic progenitors. However, the median
metallicity of the 7 broad-lined SN Ic (SN Ic-BL) in our sample is
significantly lower, log(O/H)+12 = 8.34. The age of the young stellar
population of SN Ic-BL host environments also seems to be lower than for SN Ib
and Ic, but our age sample is small. A synthesis of SN Ibc host environment
spectroscopy to date does not reveal a significant difference in SN Ib and Ic
metallicities, but reinforces the significance of the lower metallicities for
SN Ic-BL. This combined sample demonstrates that galaxy-targeted SN searches
introduce a significant bias for studies seeking to infer the metallicity
distribution of SN progenitors, and we identify and discuss other systematic
effects that play smaller roles. We discuss the path forward for making
progress on SN Ibc progenitor studies in the LSST era.Comment: 27 pages, 12 Figures, V2 as accepted by ApJ, more information at
http://www.cfa.harvard.edu/~nsanders/papers/Ibchosts/summary.htm
Situation based strategic positioning for coordinating a team of homogeneous agents
. In this paper we are proposing an approach for coordinating a team ofhomogeneous agents based on a flexible common Team Strategy as well as onthe concepts of Situation Based Strategic Positioning and Dynamic Positioningand Role Exchange. We also introduce an Agent Architecture including a specifichigh-level decision module capable of implementing this strategy. Ourproposal is based on the formalization of what is a team strategy for competingwith an opponent team having opposite goals. A team strategy is composed of aset of agent types and a set of tactics, which are also composed of several formations.Formations are used for different situations and assign each agent a defaultspatial positioning and an agent type (defining its behaviour at several levels).Agents reactivity is also introduced for appropriate response to the dynamicsof the current situation. However, in our approach this is done in a way thatpreserves team coherence instead of permitting uncoordinated agent behaviour.We have applied, with success, this coordination approach to the RoboSoccersimulated domain. The FC Portugal team, developed using this approach wonthe RoboCup2000 (simulation league) European and World championshipsscoring a total of 180 goals and conceding none
Contribution of mobile genetic elements to the competitiveness of a cystic fibrosis epidemic strain
On time's arrow in Ehrenfest models with reversible deterministic dynamics
We introduce a deterministic, time-reversible version of the Ehrenfest urn
model. The distribution of first-passage times from equilibrium to
non-equilibrium states and vice versa is calculated. We find that average times
for transition to non-equilibrium always scale exponentially with the system
size, whereas the time scale for relaxation to equilibrium depends on
microscopic dynamics. To illustrate this, we also look at deterministic and
stochastic versions of the Ehrenfest model with a distribution of microscopic
relaxation times.Comment: 6 pages, 7 figures, revte
Study of Digital Competence of the Students and Teachers in Ukraine
Professional fulfillment of the personality at the conditions of the digital economy requires the high level of digital competency. One of the ways to develop these competencies is education. However, to provide the implementation of digital education at a high level, the digital competency of the teachers and students is a must. This paper presents explanations on the level determination of the digital competencies for teachers and students in Ukraine according to the DigComp recommendations. We tried to identify the main factors that reflect the degree of readiness teachers and students for digital education based on their self-evaluation. We also attempted to estimate the level of digital competencies based on the analysis of Case-Studies execution results. The complex analysis let us assess the connection between respondents’ self-evaluation and their real competencies. Here we provide a methodology and a model of level competencies determination by means of a survey, expert case rating and the results of the statistical analysis. On the basis of the obtained results, this paper suggests further research prospects and recommendations on the digital competency development in educational institutions in Ukraine
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