Five new INTEGRAL unidentified hard X-Ray sources uncovered by Chandra

The IBIS imager on board INTEGRAL, with a sensitivity better than a mCrab in deep observations and a point source location accuracy of the order of few arcminutes, has localized so far 723 hard X-ray sources in the 17--100 keV energy band, of which a fraction of about 1/3 are still unclassified. The aim of this research is to provide sub-arcsecond localizations of the unidentified sources, necessary to pinpoint the optical and/or infrared counterpart of those objects whose nature is so far unknown. The cross-correlation between the new IBIS sources published within the fourth INTEGRAL/IBIS Survey catalogue and the CHANDRA/ACIS data archive resulted in a sample of 5 not yet identified objects. We present here the results of CHANDRA X-ray Observatory observations of these five hard X-ray sources discovered by the INTEGRAL satellite. We associated IGR J10447-6027 with IR source 2MASSJ10445192-6025115, IGR J16377-6423 with the cluster CIZA J1638.2-6420, IGR J14193-6048 with the pulsar with nebula PSR J1420-6048 and IGR J12562+2554 with the Quasar SDSSJ125610.42+260103.5. We suggest that the counterpart of IGR J12288+0052 may be an AGN/QSO type~2 at a confidence level of 90%.Comment: ApJ accepte

No quantum gravity signature from the farthest quasars

Context: Strings and other alternative theories describing the quantum properties of space-time suggest that space-time could present a foamy structure and also that, in certain cases, quantum gravity (QG) may manifest at energies much below the Planck scale. One of the observable effects could be the degradation of the diffraction images of distant sources. Aims: We searched for this degradation effect, caused by QG fluctuations, in the light of the farthest quasars (QSOs) observed by the Hubble Space Telescope with the aim of setting new limits on the fluctuations of the space-time foam and QG models. Methods: We developed a software that estimates and compares the phase variation in the interference patterns of the high-redshift QSOs, taken from the snapshot survey of HST-SDSS, with those of stars that are expected to not be affected by QG effects. We used a two-parameter function to determine, for each test star and QSO, the maximum of the diffraction pattern and to calculate the Strehl ratio. Results: Our results go far beyond those already present in the literature. By adopting the most conservative approach where the correction terms, that describe the possibility for space-time fluctuations cumulating across long distances and partially compensate for the effects of the phase variations, are taken into account. We exclude the random walk model and most of the holographic models of the space-time foam. Without considering these correction terms, all the main QG scenarios are excluded. Finally, our results show the absence of any directional dependence of QG effects and the validity of the cosmological principle with an independent method; that is, viewed on a large scale, the properties of the Universe are the same for all observers, including the effects of space-time fluctuations.Comment: 5 pages 6 figure

Multipole expansion of Bessel and Gaussian beams for Mie scattering calculations

Multipole expansions of Bessel and Gaussian beams, suitable for use in Mie scattering calculations, are derived. These results allow Mie scattering calculations to be carried out considerably faster than existing methods, something that is of particular interest for time evolution simulations where large numbers of scattering calculations must be performed. An analytic result is derived for the Bessel beam that improves on a previously published expression requiring the evaluation of an integral. An analogous expression containing a single integral, similar to existing results quoted, but not derived, in literature, is derived for a Gaussian beam,valid from the paraxial limit all the way to arbitrarily high numerical apertures

Is the Presence of Retinopathy of Practical Value in Defining Cases of Diabetic Nephropathy in Genetic Association Studies?: The Experience With the ACE Insertion/Deletion Polymorphism in 53 Studies Comprising 17,791 Subjects

OBJECTIVE— A key consideration when setting up genetic studies is the case definition. For diabetic nephropathy, the case definition is typically based on the presence of albuminuria. However, it has been long debated whether diabetic nephropathy cases defined in this way may have a high prevalence of nondiabetic kidney disease, especially if diabetic retinopathy is absent

Physical health and lifestyle predictors for significant cognitive impairment in community-dwelling Chinese older adults in Hong Kong

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Association between vascular risk factors and incident significant cognitive impairment in Chinese older people in Hong Kong in a six-year study

Objective: This study aimed to examine the association between vascular risk factors, namely hypertension, diabetes mellitus and hypercholesterolemia, and incident significant cognitive impairment in community-dwelling Chinese older people in Hong Kong. Methods: Community-dwelling Chinese older people aged 65 years and above who attended Nam Shan Elderly Health Centre in 2005 with no history of dementia or stroke constituted the baseline sample. Retrospective data retrieval for the presence of vascular risk factors at baseline was conducted. Annual clinical assessment on cognition was offered in the 6-year study period. Significant cognitive impairment was defined by presence of dementia in accordance with DSM-IV-TR, scoring below the cut-off point on the Cantonese version of the Mini-Mental State Examination, and / or a global Clinical Dementia Rating score of 1-3. Results: A total of 1925 subjects were recruited into our study; 161 (8.4%) subjects developed significant cognitive impairment in the 6-year study period. Subjects with incident significant cognitive impairment was older (75 vs. 73 years; Mann-Whitney U test, p < 0.001) with lower education attainment (30.4% vs. 23.9% of illiteracy; χ2 test, p = 0.06). However, there was no statistically significant difference in the point prevalence of pre-existing hypertension (χ2 test, p = 0.68), diabetes mellitus (χ2 test, p = 0.21), and hypercholesterolemia (χ2 test, p = 0.31) between subjects who developed significant cognitive impairment and those who remained cognitively stable. Interestingly, baseline pulse pressure, but not systolic or diastolic blood pressure, was found to be higher among subjects with incident significant cognitive impairment (70 mm Hg vs. 66 mm Hg; Mann-Whitney U test, p = 0.03). Conclusions: This study did not have evidence to show that hypertension, diabetes mellitus, and hypercholesterolemia were associated with incident significant cognitive impairment in the Chinese older people in Hong Kong. Further studies are needed to examine the role of pulse pressure in contributing to cognitive decline in late life.published_or_final_versio

Widened pulse pressure is a potential risk factor for significant cognitive impairment among community-dwelling Chinese younger old people

postprin

Atrial fibrillation impairs the diagnostic performance of cardiac natriuretic peptides in dyspneic patients. results from the BACH Study (Biomarkers in ACute Heart Failure)

Objectives: The purpose of this study was to assess the impact of atrial fibrillation (AF) on the performance of mid-region amino terminal pro-atrial natriuretic peptide (MR-proANP) in comparison with the B-type peptides (BNP and NT-proBNP) for diagnosis of acute heart failure (HF) in dyspneic patients. Background: The effects of AF on the diagnostic and prognostic performance of MR-proANP in comparison with the B type natriuretic peptides have not been previously reported. Methods: A total of 1,445 patients attending the emergency department with acute dyspnea had measurements taken of MR-proANP, BNP, and NT-proBNP values on enrollment to the BACH trial and were grouped according to presence or absence of AF and HF. Results: AF was present in 242 patients. Plasma concentrations of all three peptides were lowest in those with neither AF nor HF and AF without HF was associated with markedly increased levels (p &lt; 0.00001). HF with or without AF was associated with a significant further increment (p &lt; 0.00001 for all three markers). Areas under receiver operator characteristic curves (AUCs) for discrimination of acute HF were similar and powerful for all peptides without AF (0.893 to 0.912; all p &lt; 0.001) with substantial and similar reductions (0.701 to 0.757) in the presence of AF. All 3 peptides were independently prognostic but there was no interaction between any peptide and AF for prediction of all-cause mortality. Conclusions: AF is associated with increased plasma natriuretic peptide (MR-proANP, BNP and NT-proBNP) levels in the absence of HF. The diagnostic performance of all three peptides is impaired by AF. This warrants consideration of adjusted peptide thresholds for diagnostic use in AF and mandates the continued search for markers free of confounding by AF

Effects of rapid thermal annealing on GaAs 1-x

The effects of rapid thermal annealing on the optical and structural properties of GaAs1-xBix alloys for x ranging from 0.022 to 0.065 were investigated. At room temperature, the annealed GaAs1-xBix showed modest improvement (∼3 times) in photoluminescence (PL) while the PL peak wavelength remained relatively unchanged. It was found that bismuth related defects are not easily removed by annealing and the PL improvement may be dominated by the reduction of other types of defects including arsenic and gallium related defects. Also, the optimum annealing temperature is Bi composition dependent. For samples with x &lt; 0.048, the optimum annealing temperature is 700 °C but reduces to 600 °C for higher compositions

Infrared properties of exotic superconductors

The infrared spectra of the non-traditional superconductors share certain common features. The lack of a gap signature at $2\Delta$ and the residual conductivity are the consequence of a d-wave order parameter. The high $T_c$ materials, the organic conductors and the heavy Fermion materials have a strong mid-infrared absorption band which can be interpreted as strong coupling of the carriers to electronic degrees of freedom which leads to a breakdown of the Fermi liquid picture. The cuprates and the organic charge transfer salts are unique in possessing an intrinsic low dimensionality. The charge transport normal to the highly conducting direction is incoherent down to the lowest temperatures and frequencies.Comment: 10 pages 11 figures, From the proceedings of the First Euroconference on Anomalous Complex Superconductors, Heraklion, Crete. Sept 1998, to be published in Physica