1,547 research outputs found
Low temperature heat capacity of Fe_{1-x}Ga_{x} alloys with large magneostriction
The low temperature heat capacity C_{p} of Fe_{1-x}Ga_{x} alloys with large
magnetostriction has been investigated. The data were analyzed in the standard
way using electron () and phonon () contributions. The
Debye temperature decreases approximately linearly with increasing
Ga concentration, consistent with previous resonant ultrasound measurements and
measured phonon dispersion curves. Calculations of from lattice
dynamical models and from measured elastic constants C_{11}, C_{12} and C_{44}
are in agreement with the measured data. The linear coefficient of electronic
specific heat remains relatively constant as the Ga concentration
increases, despite the fact that the magnetoelastic coupling increases. Band
structure calculations show that this is due to the compensation of majority
and minority spin states at the Fermi level.Comment: 14 pages, 6 figure
The Conserved nhaAR Operon Is Drastically Divergent between B2 and Non-B2 Escherichia coli and Is Involved in Extra-Intestinal Virulence
The Escherichia coli species is divided in phylogenetic groups that differ in their virulence and commensal distribution. Strains belonging to the B2 group are involved in extra-intestinal pathologies but also appear to be more prevalent as commensals among human occidental populations. To investigate the genetic specificities of B2 sub-group, we used 128 sequenced genomes and identified genes of the core genome that showed marked difference between B2 and non-B2 genomes. We focused on the gene and its surrounding region with the strongest divergence between B2 and non-B2, the antiporter gene nhaA. This gene is part of the nhaAR operon, which is in the core genome but flanked by mobile regions, and is involved in growth at high pH and high sodium concentrations. Consistently, we found that a panel of non-B2 strains grew faster than B2 at high pH and high sodium concentrations. However, we could not identify differences in expression of the nhaAR operon using fluorescence reporter plasmids. Furthermore, the operon deletion had no differential impact between B2 and non-B2 strains, and did not result in a fitness modification in a murine model of gut colonization. Nevertheless, sequence analysis and experiments in a murine model of septicemia revealed that recombination in nhaA among B2 strains was observed in strains with low virulence. Finally, nhaA and nhaAR operon deletions drastically decreased virulence in one B2 strain. This effect of nhaAR deletion appeared to be stronger than deletion of all pathogenicity islands. Thus, a population genetic approach allowed us to identify an operon in the core genome without strong effect in commensalism but with an important role in extra-intestinal virulence, a landmark of the B2 strains
Heterodyne Spectroscopy of the 63 m O I Line in M42
We have used a laser heterodyne spectrometer to resolve the emission line
profile of the 63 micron 3P1 - 3P2 fine-structure transition of O I at two
locations in M42. Comparison of the peak antenna temperature with that of the
158 micron C II fine-structure line shows that the gas kinetic temperature in
the photodissociation region near theta1C is 175 - 220 K, the density is
greater than 2x10 ^5 cm-3, and the hydrogen column density is about 1.5x10 ^22
cm-2. A somewhat lower temperature and column density are found in the IRc2
region, most likely reflecting the smaller UV flux. The observed width of the O
I line is 6.8 km/s (FWHM) at theta1C, which is slightly broadened over the
intrinsic linewidth by optical depth effects. No significant other differences
between the O I and C II line profiles are seen, which shows that the narrow
emission from both neutral atomic oxygen and ionized carbon comes from the PDR.
The O I data do not rule out the possibility of weak broad-velocity emission
from shock-excited gas at IRc2, but the C II data show no such effect, as
expected from non-ionizing shock models.Comment: 11 pages including 2 postscript figures, uses aaspp4.st
Beyond universality: parametrizing ultracold complex-mediated reactions using statistical assumptions
We have calculated accurate quantum reactive and elastic cross-sections for
the prototypical barrierless reaction D + H(=0, =0) using the
hyperspherical scattering method. The considered kinetic energy ranges from the
ultracold to the Langevin regimes. The availability of accurate results for
this system allows to test the quantum theory by Jachymski et al. [Phys. Rev.
Lett. 110, 213202 (2013)] in a nonuniversal case. The short range reaction
probability is rationalized using statistical model assumptions and related to
a statistical factor. This provides a means to estimate one of the parameters
that characterizes ultracold processes from first principles. Possible
limitations of the statistical model are considered
Monitoring the Variable Interstellar Absorption toward HD 219188 with HST/STIS
We discuss the results of continued spectroscopic monitoring of the variable
intermediate-velocity (IV) absorption at v = -38 km/s toward HD 219188. After
reaching maxima in mid-2000, the column densities of both Na I and Ca II in
that IV component declined by factors >= 2 by the end of 2006. Comparisons
between HST/STIS echelle spectra obtained in 2001, 2003, and 2004 and HST/GHRS
echelle spectra obtained in 1994--1995 indicate the following: (1) The
absorption from the dominant species S II, O I, Si II, and Fe II is roughly
constant in all four sets of spectra -- suggesting that the total N(H) and the
(mild) depletions have not changed significantly over a period of nearly ten
years. (2) The column densities of the trace species C I (both ground and
excited fine-structure states) and of the excited state C II* all increased by
factors of 2--5 between 1995 and 2001 -- implying increases in the hydrogen
density n_H (from about 20 cm^{-3} to about 45 cm^{-3}) and in the electron
density n_e (by a factor >= 3) over that 6-year period. (3) The column
densities of C I and C II* -- and the corresponding inferred n_H and n_e --
then decreased slightly between 2001 and 2004. (4) The changes in C I and C II*
are very similar to those seen for Na I and Ca II. The relatively low total
N(H) and the modest n_H suggest that the -38 km/s cloud toward HD 219188 is not
a very dense knot or filament. Partial ionization of hydrogen appears to be
responsible for the enhanced abundances of Na I, C I, Ca II, and C II*. In this
case, the variations in those species appear to reflect differences in density
and ionization [and not N(H)] over scales of tens of AU.Comment: 33 pages, 6 figures, aastex, accepted to Ap
Increased Wellbeing from Social Interaction in a Secular Congregation
Religiosity appears to benefit wellbeing, potentially due to social support offered by religious communities. However, rising secularism implies that fewer people have access to these benefits. To address this problem, we investigated whether these benefits could also be obtained from membership in a secular, quasi-religious community. We conducted a longitudinal study among 92 members of the Sunday Assembly (SA), an international organization of secular congregations. SA members assemble in large services and in smaller interest groups that offer more face-to-face interaction. Once a month for six months, participants completed a questionnaire measuring wellbeing and participation in both SA and non-SA social activities. Panel analysis of longitudinal data revealed that participation in SA small-group activities positively influenced wellbeing over the six-month period, particularly among males. Participation in non-SA social activities, in contrast, had no effect on wellbeing. Aspects of the Sunday service that members perceived as most important, both for creating a sense of community and for friendship formation, were the informal socialising and cooperating that occurs before and after the service itself. Secular congregations may be a viable alternative for non-religious people (and perhaps especially men) who seek the health benefits that religious communities have traditionally offered
Atomic Diagnostics of X-ray Irradiated Protoplanetary Disks
We study atomic line diagnostics of the inner regions of protoplanetary disks
with our model of X-ray irradiated disk atmospheres which was previously used
to predict observable levels of the NeII and NeIII fine-structure transitions
at 12.81 and 15.55mum. We extend the X-ray ionization theory to sulfur and
calculate the fraction of sulfur in S, S+, S2+ and sulfur molecules. For the
D'Alessio generic T Tauri star disk, we find that the SI fine-structure line at
25.55mum is below the detection level of the Spitzer Infrared Spectrometer
(IRS), in large part due to X-ray ionization of atomic S at the top of the
atmosphere and to its incorporation into molecules close to the mid-plane. We
predict that observable fluxes of the SII 6718/6732AA forbidden transitions are
produced in the upper atmosphere at somewhat shallower depths and smaller radii
than the neon fine-structure lines. This and other forbidden line transitions,
such as the OI 6300/6363AA and the CI 9826/9852AA lines, serve as complementary
diagnostics of X-ray irradiated disk atmospheres. We have also analyzed the
potential role of the low-excitation fine-structure lines of CI, CII, and OI,
which should be observable by SOFIA and Herschel.Comment: Accepted by Ap
Cancer and renal insufficiency results of the BIRMA study
Background: Half of anticancer drugs are predominantly excreted in urine. Dosage adjustment in renal insufficiency (RI) is, therefore, a crucial issue. Moreover, patients with abnormal renal function are at high risk for drug-induced nephrotoxicity. The Belgian Renal Insufficiency and Anticancer Medications (BIRMA) study investigated the prevalence of RI in cancer patients, and the profile/dosing of anticancer drugs prescribed. Methods:Primary end point: to estimate the prevalence of abnormal glomerular filtration rate (GFR; estimated with the abbreviated Modification of Diet in Renal Disease formula) and RI in cancer patient. Secondary end point: to describe the profile of anticancer drugs prescribed (dose reduction/nephrotoxicity). Data were collected for patients presenting at one of the seven Belgian BIRMA centres in March 2006. Results: A total of 1218 patients were included. The prevalence of elevated SCR (1.2 mg per 100 ml) was 14.9%, but 64.0% had a GFR90 ml min 1 per 1.73 m 2. In all, 78.6% of treated patients (n1087) were receiving at least one drug needing dosage adjustment and 78.1% received at least one nephrotoxic drug. In all, 56.5% of RI patients receiving chemotherapy requiring dose reduction in case of RI did not receive dose adjustment. Conclusions: The RI is highly frequent in cancer patients. In all, 80% of the patients receive potentially nephrotoxic drugs and/or for which dosage must be adjusted in RI. Oncologists should check the appropriate dose of chemotherapeutic drugs in relation to renal function before prescribing. © 2010 Cancer Research UK.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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