597 research outputs found
Numerical simulations of the Warm-Hot Intergalactic Medium
In this paper we review the current predictions of numerical simulations for
the origin and observability of the warm hot intergalactic medium (WHIM), the
diffuse gas that contains up to 50 per cent of the baryons at z~0. During
structure formation, gravitational accretion shocks emerging from collapsing
regions gradually heat the intergalactic medium (IGM) to temperatures in the
range T~10^5-10^7 K. The WHIM is predicted to radiate most of its energy in the
ultraviolet (UV) and X-ray bands and to contribute a significant fraction of
the soft X-ray background emission. While O VI and C IV absorption systems
arising in the cooler fraction of the WHIM with T~10^5-10^5.5 K are seen in
FUSE and HST observations, models agree that current X-ray telescopes such as
Chandra and XMM-Newton do not have enough sensitivity to detect the hotter
WHIM. However, future missions such as Constellation-X and XEUS might be able
to detect both emission lines and absorption systems from highly ionised atoms
such as O VII, O VIII and Fe XVII.Comment: 18 pages, 5 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 14; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
Interaction between vitamin D receptor genotype and estrogen receptor alpha genotype influences vertebral fracture risk
In view of the interactions of vitamin D and the estrogen endocrine
system, we studied the combined influence of polymorphisms in the estrogen
receptor (ER) alpha gene and the vitamin D receptor (VDR) gene on the
susceptibility to osteoporotic vertebral fractures in 634 women aged 55 yr
and older. Three VDR haplotypes (1, 2, and 3) of the BsmI, ApaI, and TaqI
restriction fragment length polymorphisms and three ERalpha haplotypes (1,
2, and 3) of the PvuII and XbaI restriction fragment length polymorphisms
were identified. We captured 131 nonvertebral and 85 vertebral fracture
cases during a mean follow-up period of 7 yr. ERalpha haplotype 1 was
dose-dependently associated with increased vertebral fracture risk (P <
0.001) corresponding to an odds ratio of 1.9 [95% confidence interval
(CI), 0.9-4.1] per copy of the risk allele. VDR haplotype 1 was
overrepresented in vertebral fracture cases. There was a significant
interaction (P = 0.01) between ERalpha haplotype 1 and VDR haplotype 1 in
determining vertebral fracture risk. The association of ERalpha haplotype
1 with vertebral fracture risk was only present in homozygous carriers of
VDR haplotype 1. The risk of fracture was 2.5 (95% CI, 0.6-9.9) for
heterozygous and 10.3 (95% CI, 2.7-40) for homozygous carriers of ERalpha
haplotype 1. These associations were independent of bone mineral density.
In conclusion, interaction between ERalpha and VDR gene polymorphisms
leads to increased risk of osteoporotic vertebral fractures in women,
largely independent of bone mineral density
Interaction between vitamin D receptor genotype and estrogen receptor alpha genotype influences vertebral fracture risk
In view of the interactions of vitamin D and the estrogen endocrine
system, we studied the combined influence of polymorphisms in the estrogen
receptor (ER) alpha gene and the vitamin D receptor (VDR) gene on the
susceptibility to osteoporotic vertebral fractures in 634 women aged 55 yr
and older. Three VDR haplotypes (1, 2, and 3) of the BsmI, ApaI, and TaqI
restriction fragment length polymorphisms and three ERalpha haplotypes (1,
2, and 3) of the PvuII and XbaI restriction fragment length polymorphisms
were identified. We captured 131 nonvertebral and 85 vertebral fracture
cases during a mean follow-up period of 7 yr. ERalpha haplotype 1 was
dose-dependently associated with increased vertebral fracture risk (P <
0.001) corresponding to an odds ratio of 1.9 [95% confidence interval
(CI), 0.9-4.1] per copy of the risk allele. VDR haplotype 1 was
overrepresented in vertebral fracture cases. There was a significant
interaction (P = 0.01) between ERalpha haplotype 1 and VDR haplotype 1 in
determining vertebral fracture risk. The association of ERalpha haplotype
1 with vertebral fracture risk was only present in homozygous carriers of
VDR haplotype 1. The risk of fracture was 2.5 (95% CI, 0.6-9.9) for
heterozygous and 10.3 (95% CI, 2.7-40) for homozygous carriers of ERalpha
haplotype 1. These associations were independent of bone mineral density.
In conclusion, interaction between ERalpha and VDR gene polymorphisms
leads to increased risk of osteoporotic vertebral fractures in women,
largely independent of bone mineral density
Association of 5' estrogen receptor alpha gene polymorphisms with bone mineral density, vertebral bone area and fracture risk
This study investigates the influence of genetic variation of the estrogen receptor alpha (ESR1) gene locus on several bone parameters in 2042 individuals of The Rotterdam Study, a prospective population-based cohort study of elderly subjects. We analysed three polymorphic sites in the 5' region of the ESR1 gene; a (TA)(n)-repeat in the promoter region, and molecular haplotypes of the PvuII and XbaI RFLPs in intron 1, and inferred long-range haplotypes (LRH) thereof. We observed only three of the possible four PvuII-XbaI haplotypes in our population. A comparison with other Caucasian populations showed similar haplotype frequencies, while in Asian and African populations these were different. Linkage disequilibrium (LD) analysis between the PvuII-XbaI haplotype and the (TA)(n) repeat showed strong LD between the two sites. Reconstruction of long range haplotypes over the entire 5' region, revealed six frequent LRH. In men, we did not observe an association between the ESR1 polymorphisms studied
Search for the Rare Decays J/Psi --> Ds- e+ nu_e, J/Psi --> D- e+ nu_e, and J/Psi --> D0bar e+ e-
We report on a search for the decays J/Psi --> Ds- e+ nu_e + c.c., J/Psi -->
D- e+ nu_e + c.c., and J/Psi --> D0bar e+ e- + c.c. in a sample of 5.8 * 10^7
J/Psi events collected with the BESII detector at the BEPC. No excess of signal
above background is observed, and 90% confidence level upper limits on the
branching fractions are set: B(J/Psi --> Ds- e+ nu_e + c.c.)<4.8*10^-5, B(J/Psi
--> D- e+ nu_e + c.c.) D0bar e+ e- + c.c.)<1.1*10^-5Comment: 10 pages, 4 figure
Study of J/psi decays to Lambda Lambdabar and Sigma0 Sigma0bar
The branching ratios and Angular distributions for J/psi decays to Lambda
Lambdabar and Sigma0 Sigma0bar are measured using BESII 58 million J/psi.Comment: 11 pages, 5 figure
Measurements of the observed cross sections for exclusive light hadron production in e^+e^- annihilation at \sqrt{s}= 3.773 and 3.650 GeV
By analyzing the data sets of 17.3 pb taken at GeV
and 6.5 pb taken at GeV with the BESII detector at the
BEPC collider, we have measured the observed cross sections for 12 exclusive
light hadron final states produced in annihilation at the two energy
points. We have also set the upper limits on the observed cross sections and
the branching fractions for decay to these final states at 90%
C.L.Comment: 8 pages, 5 figur
Measurements of J/psi Decays into 2(pi+pi-)eta and 3(pi+pi-)eta
Based on a sample of 5.8X 10^7 J/psi events taken with the BESII detector,
the branching fractions of J/psi--> 2(pi+pi-)eta and J/psi-->3(pi+pi-)eta are
measured for the first time to be (2.26+-0.08+-0.27)X10^{-3} and
(7.24+-0.96+-1.11)X10^{-4}, respectively.Comment: 11 pages, 6 figure
Measurements of the Mass and Full-Width of the Meson
In a sample of 58 million events collected with the BES II detector,
the process J/ is observed in five different decay
channels: , , (with ), (with
) and . From a combined fit of all five
channels, we determine the mass and full-width of to be
MeV/ and
MeV/.Comment: 9 pages, 2 figures and 4 table. Submitted to Phys. Lett.
Search for the Lepton Flavor Violation Processes and
The lepton flavor violation processes and are
searched for using a sample of 5.8 events collected with
the BESII detector. Zero and one candidate events, consistent with the
estimated background, are observed in and
decays, respectively. Upper limits on the branching ratios are determined to be
and at the 90% confidence level (C.L.).Comment: 9 pages, 2 figure
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