4,755 research outputs found
Metabolomics reveals effects of maternal smoking on endogenous metabolites from lipid metabolism in cord blood of newborns
Introduction: A general detrimental effect of smoking during pregnancy on the health of newborn children is well-documented, but the detailed mechanisms remain elusive. Objectives: Beside the specific influence of environmental tobacco smoke derived toxicants on developmental regulation the impact on the metabolism of newborn children is of particular interest, first as a general marker of foetal development and second due to its potential predictive value for the later occurrence of metabolic diseases. Methods: Tobacco smoke exposure information from a questionnaire was confirmed by measuring the smoking related metabolites S-Phenyl mercapturic acid, S-Benzyl mercapturic acid and cotinine in maternal urine by LC–MS/MS. The impact of smoking on maternal endogenous serum metabolome and children’s cord blood metabolome was assessed in a targeted analysis of 163 metabolites by an LC–MS/MS based assay. The anti-oxidative status of maternal serum samples was analysed by chemoluminiscence based method. Results: Here we present for the first time results of a metabolomic assessment of the cordblood of 40 children and their mothers. Several analytes from the group of phosphatidylcholines, namely PCaaC28:1, PCaaC32:3, PCaeC30:1, PCaeC32:2, PCaeC40:1, and sphingomyelin SM C26:0, differed significantly in mothers and children’s sera depending on smoking status. In serum of smoking mothers the antioxidative capacity of water soluble compounds was not significantly changed while there was a significant decrease in the lipid fraction. Conclusion: Our data give evidence that smoking during pregnancy alters both the maternal and children’s metabolome. Whether the different pattern found in adults compared to newborn children could be related to different disease outcomes should be in the focus of future studies
Solar Mikheyev-Smirnov-Wolfenstein Effect with Three Generations of Neutrinos
Under the assumption that the density variation of the electrons can be
approximated by an exponential function, the solar Mikheyev-Smirnov-Wolfenstein
effect is treated for three generations of neutrinos. The generalized
hypergeometric functions that result from the exact solution of this problem
are studied in detail, and a method for their numerical evaluation is
presented. This analysis plays a central role in the determination of neutrino
masses, not only the differences of their squares, under the assumption of
universal quark-lepton mixing.Comment: 22 pages, LaTeX, including 2 figure
Towards absolute scales of radii and masses of open clusters
Aims: In this paper we derive tidal radii and masses of open clusters in the
nearest kiloparsecs around the Sun. Methods: For each cluster, the mass is
estimated from tidal radii determined from a fitting of three-parametric King's
profiles to the observed integrated density distribution. Different samples of
members are investigated. Results: For 236 open clusters, all contained in the
catalogue ASCC-2.5, we obtain core and tidal radii, as well as tidal masses.
The distributions of the core and tidal radii peak at about 1.5 pc and 7 - 10
pc, respectively. A typical relative error of the core radius lies between 15%
and 50%, whereas, for the majority of clusters, the tidal radius was determined
with a relative accuracy better than 20%. Most of the clusters have tidal
masses between 50 and 1000 , and for about half of the clusters, the
masses were obtained with a relative error better than 50%.Comment: 11 pages, 7 figures, accepted for publication in Astronomy &
Astrophysic
Spectral Decorrelation of Nuclear Levels in the Presence of Continuum Decay
The fluctuation properties of nuclear giant resonance spectra are studied in
the presence of continuum decay. The subspace of quasi-bound states is
specified by one-particle one-hole and two-particle two-hole excitations and
the continuum coupling is generated by a scattering ensemble. It is found that,
with increasing number of open channels, the real parts of the complex
eigenvalues quickly decorrelate. This appears to be related to the transition
from power-law to exponential time behavior of the survival probability of an
initially non-stationary state.Comment: 10 Pages, REVTEX, 4 PostScript figure
Neighbourhood greenness and income of occupants in four German areas: GINIplus and LISAplus
Objective We investigated whether families with lower individual-level socioeconomic status (SES) reside in less green neighbourhoods in four areas in Germany. Methods Data were collected within two German birth cohorts – GINIplus and LISAplus. Net equivalent household income was categorized into study area-specific tertiles and used as a proxy for individual-level SES. Neighbourhood greenness was calculated in 500-m buffers around home addresses as: 1) the mean normalized difference vegetation index (NDVI); 2) percent tree cover. Associations between income and neighbourhood greenness were assessed per study area using adjusted linear regression models. Results In the Munich and Leipzig areas, families in the low and medium income tertiles resided in neighbourhoods with lower NDVI compared to those in the high income tertile (mean percent change in NDVI: −4.0 (95% confidence interval = −6.7 to −1.3) and −5.5 (−10.9 to −0.2), respectively). In contrast, in the Wesel area, families in the low income tertile resided in neighbourhoods with higher NDVI (2.9 (0.5–5.3)). Only the association in the Munich area was replicated when using tree cover instead of the NDVI. Conclusions This study provides suggestive evidence that the presence and direction of associations between greenness and SES is region-specific in Germany. The degree of urbanization did not clarify this heterogeneity completely
Measurement of Spin Correlation Parameters A, A, and A_ at 2.1 GeV in Proton-Proton Elastic Scattering
At the Cooler Synchrotron COSY/J\"ulich spin correlation parameters in
elastic proton-proton (pp) scattering have been measured with a 2.11 GeV
polarized proton beam and a polarized hydrogen atomic beam target. We report
results for A, A, and A_ for c.m. scattering angles between
30 and 90. Our data on A -- the first measurement of this
observable above 800 MeV -- clearly disagrees with predictions of available of
pp scattering phase shift solutions while A and A_ are reproduced
reasonably well. We show that in the direct reconstruction of the scattering
amplitudes from the body of available pp elastic scattering data at 2.1 GeV the
number of possible solutions is considerably reduced.Comment: 4 pages, 4 figure
Calculated optical properties of Si, Ge, and GaAs under hydrostatic pressure
The macroscopic dielectric function in the random-phase-approximation without
local field effect has been implemented using the local density approximation
with an all electron, full-potential linear muffin-tin orbital basis-set. This
method is used to investigate the optical properties of the semiconductors Si,
Ge, and GaAs under hydrostatic pressure. The pressure dependence of the
effective dielectric function is compared to the experimental data of Go\~ni
and coworkers, and an excellent agreement is found when the so called
``scissors-operator'' shift (SOS) is used to account for the correct band gap
at . The effect of the semi-core states in the interband
transitions hardly changes the static dielectric function, ;
however, their contribution to the intensity of absorption for higher photon
energies is substantial. The spin-orbit coupling has a significant effect on
of Ge and GaAs, but not of Si. The peak in the
dynamical dielectric function is strongly underestimated for Si, but only
slightly for Ge and GaAs, suggesting that excitonic effects might be important
only for Si.Comment: 29 RevTex pages and 12 figs; in press in Physical Review
Rate-equation calculations of the current flow through two-site molecular device and DNA-based junction
Here we present the calculations of incoherent current flowing through the
two-site molecular device as well as the DNA-based junction within the
rate-equation approach. Few interesting phenomena are discussed in detail.
Structural asymmetry of two-site molecule results in rectification effect,
which can be neutralized by asymmetric voltage drop at the molecule-metal
contacts due to coupling asymmetry. The results received for poly(dG)-poly(dC)
DNA molecule reveal the coupling- and temperature-independent saturation effect
of the current at high voltages, where for short chains we establish the
inverse square distance dependence. Besides, we document the shift of the
conductance peak in the direction to higher voltages due to the temperature
decrease.Comment: 12 pages, 6 figure
WARNING: Physics Envy May Be Hazardous To Your Wealth!
The quantitative aspirations of economists and financial analysts have for
many years been based on the belief that it should be possible to build models
of economic systems - and financial markets in particular - that are as
predictive as those in physics. While this perspective has led to a number of
important breakthroughs in economics, "physics envy" has also created a false
sense of mathematical precision in some cases. We speculate on the origins of
physics envy, and then describe an alternate perspective of economic behavior
based on a new taxonomy of uncertainty. We illustrate the relevance of this
taxonomy with two concrete examples: the classical harmonic oscillator with
some new twists that make physics look more like economics, and a quantitative
equity market-neutral strategy. We conclude by offering a new interpretation of
tail events, proposing an "uncertainty checklist" with which our taxonomy can
be implemented, and considering the role that quants played in the current
financial crisis.Comment: v3 adds 2 reference
Probing the origins of vibrational mode specificity in intramolecular dynamics through picosecond time-resolved photoelectron imaging studies
We have studied the intramolecular dynamics induced by selective photoexcitation of two near-isoenergetic vibrational states in S1 p-fluorotoluene using picosecond time-resolved photoelectron imaging. We find that similar dynamics ensue following the preparation of the 13111 and 7a111 states that lie at 1990 cm-1 and 2026 cm-1, and that these dynamics are mediated by a single strongly coupled doorway state in each case. However, the lifetimes differ by a factor of three, suggesting an influence of the vibrational character of the modes involved. Our results clearly show the contribution of torsion-vibration coupling to the dynamics; this is further corroborated by comparison with the 7a111 state in S1 p-difluorobenzene, which lies at 2068 cm-1. We invoke a model in which van der Waals interactions between methyl hydrogen atoms and nearby ring carbon and hydrogen atoms leads to mixing of the vibrational and torsional states. This model predicts that enhanced torsion-vibration coupling occurs when mode 7a is excited, consistent with our observations
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