2,602 research outputs found
BL LAC PKSB1144-379 an extreme scintillator
Rapid variability in the radio flux density of the BL Lac object PKSB1144-379
has been observed at four frequencies, ranging from 1.5 to 15 GHz, with the VLA
and the University of Tasmania's Ceduna antenna. Intrinsic and line of sight
effects were examined as possible causes of this variability, with interstellar
scintillation best explaining the frequency dependence of the variability
timescales and modulation indices. This scintillation is consistent with a
compact source 20-40 microarcseconds, or 0.15-0.3 pc in size. The inferred
brightness temperature for PKSB1144-379 (assuming that the observed variations
are due to scintillation) is 6.2e12 K at 4.9 GHz, with approximately 10 percent
of the total flux in the scintillating component. We show that scintillation
surveys aimed at identifying variability timescales of days to weeks are an
effective way to identify the AGN with the highest brightness temperatures.Comment: 6 pages, 3 figures, accepted for publication in ApJ Letter
Effect of asymmetry of the radio source distribution on the apparent proper motion kinematic analysis
A new list of physical characteristics of 4261 astrometric radio sources,
including all 717 ICRF-Ext.2 sources has been compiled. Comparison of our data
of optical characteristics with the official International Earth Rotation and
Reference Systems Service (IERS) list showed significant discrepancies for
about half of 667 common sources. We also found that asymmetry in the radio
sources distribution between hemispheres could cause significant correlation
between the vector spherical harmonics, especially if the case of sparse
distribution of the sources with high redshift. We identified radio sources
having many-year observation history and lack redshift. This sources should be
urgently observed at large optical telescopes. The list of optical
characteristics created in this paper is recommended for use as a supplement
material for the next International Celestial Reference Frame (ICRF)
realization. It can be also effectively used for cosmological studies and
planning of observing programs both in radio and optics.Comment: 9 page
Lifestyle factors and ovarian cancer outcomes
Purpose: Few studies have reported on the lifestyle characteristics of ovarian cancer survivors. The objectives of this study were to characterize the associations between physical activity (PA) and body size (BS) with health-related quality of life (HRQOL) and ovarian cancer recurrence in a sample of regional and distal stage ovarian cancer survivors.
Methods: Epithelial ovarian cancer survivors in their first clinical remission, with no evidence of recurrent disease were identified from The University of Texas MD Anderson Cancer Center tumor registry. A total of 51 survivors consented to participate in a battery of self-reported questionnaires. Trained staff collected data on anthropometric and recurrence data were collected from the tumor registry. Generalized linear models were used to assess the relationship between PA, BS, and HRQOL. Cox proportional hazard models were used to assess the associations between PA, BS, and recurrence-free survival.
Results: Most (59%) women were overweight or obese (BMI \u3c 25 kg/m2) , 49% met current guidelines for PA (150 minutes of moderate to vigorous PA/week), and 29% displayed characteristics of abdominal obesity (\u3e88 centimeters). Women who were not obese reported significantly higher (better) overall HRQOL (point difference = 10.8, P \u3c 0.05) and mental health (point difference = 12.4, P \u3c 0.05) scores than women who were obese. Elevated waist circumference and physical activity were not significantly associated with HRQOL outcomes and we did not find any associations between lifestyle behaviors and recurrence free survival (all P \u3e 0.05).
Conclusions: Ovarian cancer survivors with characteristics of overall and abdominal obesity may be at risk for deficits in HRQOL and could benefit from interventions designed to reduce weight. More research is needed to determine whether meeting guidelines for physical activity is associated with improvements in health outcomes this population
Identification of the Early Fermi LAT Gamma-Ray Bright Objects with Extragalactic VLBI sources
A list of 205 gamma-ray strong objects was reported recently as a result of a
3-month integration with the Large Area Telescope on board the Fermi Gamma-Ray
Space Telescope. We attempted identification of these objects,
cross-correlating the gamma-ray positions with VLBI positions of a large
all-sky sample of extragalactic radio sources selected on the basis of their
parsec-scale flux density. The original associations reported by the Fermi team
are confirmed and six new identifications are suggested. A Monte-Carlo analysis
shows that the fraction of chance associations in our analysis is less than 5
per cent, and confirms that the vast majority of gamma-ray bright extragalactic
sources are radio loud blazars with strong parsec-scale jets. A correlation
between the parsec-scale radio and gamma-ray flux is supported by our analysis
of a complete VLBI flux-density-limited sample of extragalactic jets. The
effectiveness of using a VLBI catalog to find associations between gamma-ray
detections and compact extragalactic radio sources, especially near the
Galactic plane, is demonstrated. It is suggested that VLBI catalogs should be
used for future identification of Fermi LAT objects.Comment: 5 pages, 4 figures, 1 table, accepted by the Astrophysical Journal
Letters; minor corrections to the text are made, one panel is added to Figure
1; full table 1 in electronic form can be extracted from the preprint sourc
The cyclin-dependent kinase inhibitor p57(Kip2) is epigenetically regulated in carboplatin resistance and results in collateral sensitivity to the CDK inhibitor seliciclib in ovarian cancer
Carboplatin remains a first-line agent in the management of epithelial ovarian cancer (EOC). Unfortunately, platinum-resistant disease ultimately occurs in most patients. Using a novel EOC cell line with acquired resistance to carboplatin: PEO1CarbR, genome-wide micro-array profiling identified the cyclin-dependent kinase inhibitor p57(Kip2) as specifically downregulated in carboplatin resistance. Presently, we describe confirmation of these preliminary data with a variety of approaches
Venus Express radio occultation observed by PRIDE
Context. Radio occultation is a technique used to study planetary atmospheres
by means of the refraction and absorption of a spacecraft carrier signal
through the atmosphere of the celestial body of interest, as detected from a
ground station on Earth. This technique is usually employed by the deep space
tracking and communication facilities (e.g., NASA's Deep Space Network (DSN),
ESA's Estrack). Aims. We want to characterize the capabilities of the Planetary
Radio Interferometry and Doppler Experiment (PRIDE) technique for radio
occultation experiments, using radio telescopes equipped with Very Long
Baseline Interferometry (VLBI) instrumentation. Methods. We conducted a test
with ESA's Venus Express (VEX), to evaluate the performance of the PRIDE
technique for this particular application. We explain in detail the data
processing pipeline of radio occultation experiments with PRIDE, based on the
collection of so-called open-loop Doppler data with VLBI stations, and perform
an error propagation analysis of the technique. Results. With the VEX test case
and the corresponding error analysis, we have demonstrated that the PRIDE setup
and processing pipeline is suited for radio occultation experiments of
planetary bodies. The noise budget of the open-loop Doppler data collected with
PRIDE indicated that the uncertainties in the derived density and temperature
profiles remain within the range of uncertainties reported in previous Venus'
studies. Open-loop Doppler data can probe deeper layers of thick atmospheres,
such as that of Venus, when compared to closed-loop Doppler data. Furthermore,
PRIDE through the VLBI networks around the world, provides a wide coverage and
range of large antenna dishes, that can be used for this type of experiments
Maternal obesity, length of gestation, risk of postdates pregnancy and spontaneous onset of labour at term
RNA Oxidation Adducts 8-OHG and 8-OHA Change with Aβ42 Levels in Late-Stage Alzheimer's Disease
While research supports amyloid-β (Aβ) as the etiologic agent of Alzheimer's disease (AD), the mechanism of action remains unclear. Evidence indicates that adducts of RNA caused by oxidation also represent an early phenomenon in AD. It is currently unknown what type of influence these two observations have on each other, if any. We quantified five RNA adducts by gas chromatography/mass spectroscopy across five brain regions from AD cases and age-matched controls. We then used a reductive directed analysis to compare the RNA adducts to common indices of AD neuropathology and various pools of Aβ. Using data from four disease-affected brain regions (Brodmann's Area 9, hippocampus, inferior parietal lobule, and the superior and middle temporal gyri), we found that the RNA adduct 8-hydroxyguanine (8-OHG) decreased, while 8-hydroxyadenine (8-OHA) increased in AD. The cerebellum, which is generally spared in AD, did not show disease related changes, and no RNA adducts correlated with the number of plaques or tangles. Multiple regression analysis revealed that SDS-soluble Aβ42 was the best predictor of changes in 8-OHG, while formic acid-soluble Aβ42 was the best predictor of changes in 8-OHA. This study indicates that although there is a connection between AD related neuropathology and RNA oxidation, this relationship is not straightforward
Zinc Overload Enhances APP Cleavage and Aβ Deposition in the Alzheimer Mouse Brain
BACKGROUND: Abnormal zinc homeostasis is involved in β-amyloid (Aβ) plaque formation and, therefore, the zinc load is a contributing factor in Alzheimer's disease (AD). However, the involvement of zinc in amyloid precursor protein (APP) processing and Aβ deposition has not been well established in AD animal models in vivo. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, APP and presenilin 1 (PS1) double transgenic mice were treated with a high dose of zinc (20 mg/ml ZnSO4 in drinking water). This zinc treatment increased APP expression, enhanced amyloidogenic APP cleavage and Aβ deposition, and impaired spatial learning and memory in the transgenic mice. We further examined the effects of zinc overload on APP processing in SHSY-5Y cells overexpressing human APPsw. The zinc enhancement of APP expression and cleavage was further confirmed in vitro. CONCLUSIONS/SIGNIFICANCE: The present data indicate that excess zinc exposure could be a risk factor for AD pathological processes, and alteration of zinc homeostasis is a potential strategy for the prevention and treatment of AD
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