59 research outputs found
A Keleti-KĂĄrpĂĄtok fiatal vulkĂĄni Ă©s a hazai erubĂĄz talajok agyagĂĄsvĂĄnyos összetĂ©telĂ©nek összehasonlĂtĂĄsa
Discovery of the spectroscopic binary nature of six southern Cepheids
We present the analysis of photometric and spectroscopic data of six bright
Galactic Cepheids: GH Carinae, V419 Centauri, V898 Centauri, AD Puppis, AY
Sagittarii, and ST Velorum. Based on new radial velocity data (in some cases
supplemented with earlier data available in the literature), these Cepheids
have been found to be members in spectroscopic binary systems. V898 Cen turned
out to have one of the largest orbital radial velocity amplitude (> 40 km/s)
among the known binary Cepheids. The data are insufficient to determine the
orbital periods nor other orbital elements for these new spectroscopic
binaries.
These discoveries corroborate the statement on the high frequency of
occurrence of binaries among the classical Cepheids, a fact to be taken into
account when calibrating the period-luminosity relationship for Cepheids.
We have also compiled all available photometric data that revealed that the
pulsation period of AD Pup, the longest period Cepheid in this sample, is
continuously increasing with Delta P = 0.004567 d/century, likely to be caused
by stellar evolution. The wave-like pattern superimposed on the parabolic O-C
graph of AD Pup may well be caused by the light-time effect in the binary
system. ST Vel also pulsates with a continuously increasing period. The other
four Cepheids are characterised with stable pulsation periods in the last half
century.Comment: accepted by the MNRAS, 11 pages, 16 figures, 18 tables, a part of the
data can be downloaded from the online version of this articl
Optimized Herschel/PACS photometer observing and data reduction strategies for moving solar system targets
The "TNOs are Cool!: A survey of the trans-Neptunian region" is a Herschel
Open Time Key Program that aims to characterize planetary bodies at the
outskirts of the Solar System using PACS and SPIRE data, mostly taken as
scan-maps. In this paper we summarize our PACS data reduction scheme that uses
a modified version of the standard pipeline for basic data reduction, optimized
for faint, moving targets. Due to the low flux density of our targets the
observations are confusion noise limited or at least often affected by bright
nearby background sources at 100 and 160\,m. To overcome these problems we
developed techniques to characterize and eliminate the background at the
positions of our targets and a background matching technique to compensate for
pointing errors. We derive a variety of maps as science data products that are
used depending on the source flux and background levels and the scientific
purpose. Our techniques are also applicable to a wealth of other Herschel solar
system photometric observations, e.g. comets and near-Earth asteroids. The
principles of our observing strategies and reduction techniques for moving
targets will also be applicable for similar surveys of future infrared space
projects.Comment: Accepted for publication in Experimental Astronom
A felszĂnmozgĂĄs zĂłnĂĄjĂĄban elĆfordulĂł ĂŒledĂ©kes kĆzetek ĂĄsvĂĄnyos összetĂ©telĂ©nek Ă©s fizikai tulajdonsĂĄgainak vizsgĂĄlata Kulcs terĂŒletĂ©n
Structure and evolution of debris disks around F-type stars: I. Observations, database and basic evolutionary aspects
Although photometric and spectroscopic surveys with the Spitzer Space
Telescope increased remarkably the number of well studied debris disks around
A-type and Sun-like stars, detailed analyzes of debris disks around F-type
stars remained less frequent. Using the MIPS camera and the IRS spectrograph we
searched for debris dust around 82 F-type stars with Spitzer. We found 27 stars
that harbor debris disks, nine of which are new discoveries. The dust
distribution around two of our stars, HD 50571 and HD 170773, was found to be
marginally extended on the 70um MIPS images. Combining the MIPS and IRS
measurements with additional infrared and submillimeter data, we achieved
excellent spectral coverage for most of our debris systems. We have modeled the
excess emission of 22 debris disks using a single temperature dust ring model
and of 5 debris systems with two-temperature models. The latter systems may
contain two dust rings around the star. In accordance with the expected trends,
the fractional luminosity of the disks declines with time, exhibiting a decay
rate consistent with the range of model predictions. We found the distribution
of radial dust distances as a function of age to be consistent with the
predictions of both the self stirred and the planetary stirred disk evolution
models. A more comprehensive investigation of the evolution of debris disks
around F-type stars, partly based on the presented data set, will be the
subject of an upcoming paper.Comment: Accepted for publication in ApJS, 42 pages, 18 figures, 8 tables
(emulateapj style
C-Reactive Protein (CRP) Gene Polymorphisms, CRP Levels, and Risk of Incident Coronary Heart Disease in Two Nested Case-Control Studies
Background: C-reactive protein (CRP), an acute phase reactant and marker of inflammation, has been shown to predict risk of incident cardiovascular events. However, few studies have comprehensively examined six common single-nucleotide polymorphisms (SNPs) in the CRP gene, haplotypes, and plasma CRP levels with risk of coronary heart disease (CHD). Methods and Findings: We conducted parallel nested case-control studies within two ongoing, prospective cohort studies of U.S. women (Nurses' Health Study) and men (Health Professionals Follow-up Study). Blood samples were available in a subset of 32,826 women and 18,225 men for biomarker and DNA analyses. During 8 and 6 years of follow-up, 249 women and 266 men developed incident nonfatal myocardial infarction or fatal CHD, and controls (498 women, 531 men) were matched 2:1 on age, smoking, and date of blood draw from participants free of cardiovascular disease at the time the case was diagnosed. Among both women and men, minor alleles were significantly associated with higher CRP levels for SNPs 1919A greater than T and 4741G greater than C, but associated with lower CRP levels for SNPs 2667G greater than C and 3872C greater than T. SNP 2667G greater than C was individually associated with increased risk of CHD in both women [OR 1.57 (95% CI 1.01â2.44); pâ=â0.047] and men [1.93 (95% CI 1.30â2.88); pâ=â0.001]. Two of the five common haplotypes were associated with lower CRP levels, and Haplotype 4 which included minor alleles for 2667 and 3872 was associated with significantly lower CRP levels and an elevated risk of CHD. The remaining SNPs or haplotypes were not associated with CHD in both populations. Conclusions: Common variation in the CRP gene was significantly associated with plasma CRP levels; however, the association between common SNPs and CRP levels did not correspond to a predicted change in CHD risk. The underlying inflammatory processes which predict coronary events cannot be captured solely by variation in the CRP gene
Common Variants in CRP and LEPR Influence High Sensitivity C-Reactive Protein Levels in North Indians
BACKGROUND: High sensitivity C-reactive protein (hsCRP) levels are shown to be influenced by genetic variants in Europeans; however, little is explored in Indian population. METHODS: Herein, we comprehensively evaluated association of all previously reported genetic determinants of hsCRP levels, including 18 cis (proximal to CRP gene) and 73 trans-acting (distal to CRP gene) variants in 4,200 North Indians of Indo-European ethnicity. First, we evaluated association of 91 variants from 12 candidate loci with hsCRP levels in 2,115 North Indians (1,042 non-diabetic subjects and 1,073 patients with type 2 diabetes). Then, cis and trans-acting variants contributing maximally to hsCRP level variation were further replicated in an independent 2,085 North Indians (1,047 patients with type 2 diabetes and 1,038 non-diabetic subjects). RESULTS: We found association of 12 variants from CRP, LEPR, IL1A, IL6, and IL6R with hsCRP levels in non-diabetic subjects. However, only rs3093059-CRP [ÎČâ=â0.33, Pâ=â9.6Ă10â»â”] and the haplotype harboring rs3093059 risk allele [ÎČâ=â0.32 ”g/mL, Pâ=â1.4Ă10â»âŽ/P(perm)â=â9.0Ă10â»âŽ] retained significance after correcting for multiple testing. The cis-acting variant rs3093059-CRP had maximum contribution to the variance in hsCRP levels (1.14%). Among, trans-acting variants, rs1892534-LEPR was observed to contribute maximally to hsCRP level variance (0.59%). Associations of rs3093059-CRP and rs1892534-LEPR were confirmed by replication and attained higher significance after meta-analysis [ÎČ(meta)â=â0.26/0.22; P(meta)â=â4.3Ă10â»â·/7.4Ă10â»Âł and ÎČ(meta)â=â-0.15/-0.12; P(meta)â=â2.0Ă10â»â¶/1.6Ă10â»â¶ for rs3093059 and rs1892534, respectively in non-diabetic subjects and all subjects taken together]. CONCLUSION: In conclusion, we identified rs3093059 in CRP and rs1892534 in LEPR as major cis and trans-acting contributor respectively, to the variance in hsCRP levels in North Indian population
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