A very deep Chandra observation of Abell 1795: The Cold Front and Cooling Wake

We present a new analysis of very deep Chandra observations of the galaxy cluster Abell 1795. Utilizing nearly 750 ks of net ACIS imaging, we are able to resolve the thermodynamic structure of the Intracluster Medium (ICM) on length scales of ~ 1 kpc near the cool core. We find several previously unresolved structures, including a high pressure feature to the north of the BCG that appears to arise from the bulk motion of Abell 1795's cool core. To the south of the cool core, we find low temperature (~ 3 keV), diffuse ICM gas extending for distances of ~ 50 kpc spatially coincident with previously identified filaments of H-alpha emission. Gas at similar temperatures is also detected in adjacent regions without any H-alpha emission. The X-ray gas coincident with the H-alpha filament has been measured to be cooling spectroscopically at a rate of ~ 1 Solar Masses/ yr, consistent with measurements of the star formation rate in this region as inferred from UV observations, suggesting that the star formation in this filament as inferred by its H$\alpha$ and UV emission can trace its origin to the rapid cooling of dense, X-ray emitting gas. The H-alpha filament is not a unique site of cooler ICM, however, as ICM at similar temperatures and even higher metallicities not cospatial with H$\alpha$ emission is observed just to the west of the H-alpha filament, suggesting that it may have been uplifted by Abell 1795's central active galaxy. Further simulations of cool core sloshing and AGN feedback operating in concert with one another will be necessary to understand how such a dynamic cool core region may have originated and why the H-alpha emission is so localized with respect to the cool X-ray gas despite the evidence for a catastrophic cooling flow.Comment: 14 Pages, 10 Figures, Resubmitted to ApJ after first referee report, Higher Resolution Figures available upon reques

X-ray bright active galactic nuclei in massive galaxy clusters III: New insights into the triggering mechanisms of cluster AGN

We present the results of a new analysis of the X-ray selected Active Galactic Nuclei (AGN) population in the vicinity of 135 of the most massive galaxy clusters in the redshift range of 0.2 < z < 0.9 observed with Chandra. With a sample of more than 11,000 X-ray point sources, we are able to measure, for the first time, evidence for evolution in the cluster AGN population beyond the expected evolution of field AGN. Our analysis shows that overall number density of cluster AGN scales with the cluster mass as $\sim M_{500}^{-1.2}$. There is no evidence for the overall number density of cluster member X-ray AGN depending on the cluster redshift in a manner different than field AGN, nor there is any evidence that the spatial distribution of cluster AGN (given in units of the cluster overdensity radius r_500) strongly depends on the cluster mass or redshift. The $M^{-1.2 \pm 0.7}$ scaling relation we measure is consistent with theoretical predictions of the galaxy merger rate in clusters, which is expected to scale with the cluster velocity dispersion, $\sigma$, as $\sim \sigma^{-3}$ or $\sim M^{-1}$. This consistency suggests that AGN in clusters may be predominantly triggered by galaxy mergers, a result that is further corroborated by visual inspection of Hubble images for 23 spectroscopically confirmed cluster member AGN in our sample. A merger-driven scenario for the triggering of X-ray AGN is not strongly favored by studies of field galaxies, however, suggesting that different mechanisms may be primarily responsible for the triggering of cluster and field X-ray AGN.Comment: 21 Pages, 8 figures, 5 tables. Submitted to MNRAS. Comments are welcome, and please request Steven Ehlert for higher resolution figure

Glucocorticoid sensitivity of circulating monocytes in essential hypertension

Background: Essential hypertension ranks among the strongest cardiovascular risk factors. Cytokine production by monocytes plays a key role in atherosclerosis development and acute coronary syndromes. We investigated whether stimulated monocyte cytokine release and its inhibition by glucocorticoids would differ between hypertensive and normotensive subjects. Methods: Study participants were 222 middle-aged male employees with industrial jobs. Following the criteria of the World Health Organization/International Society for Hypertension, 76 subjects were classified as being hypertensive (systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg). In vitro monocyte tumor necrosis factor (TNF)-α release after lipopolysaccharide (LPS) stimulation was assessed with and without coincubation with incremental doses of dexamethasone. Monocyte glucocorticoid sensitivity was defined as the dexamethasone concentration inhibiting TNF-α release by 50%. Results: Hypertensive subjects showed 11% higher LPS-stimulated TNF-α release than normotensive subjects (F1,181= 5.21, P = .024). In hypertensive subjects, monocyte glucocorticoid sensitivity was 21% lower than in normotensive subjects (F1,178= 4.94, P = .027), indicating that dexamethasone inhibited relatively less TNF-α release in hypertensive subjects. Results held significance when a set of classic cardiovascular risk factors was controlled for. Conclusion: The findings suggest that proinflammatory activity of circulating monocytes is higher in hypertensive than in normotensive men, providing one potential pathway to explain the increased atherosclerotic risk with essential hypertension. Am J Hypertens 2004;17:489-494 © 2004 American Journal of Hypertension, Lt

Probing the extreme realm of AGN feedback in the massive galaxy cluster, RX J1532.9+3021

We present a detailed Chandra, XMM-Newton, VLA and HST analysis of one of the strongest cool core clusters known, RX J1532.9+3021 (z=0.3613). Using new, deep 90 ks Chandra observations, we confirm the presence of a western X-ray cavity or bubble, and report on a newly discovered eastern X-ray cavity. The total mechanical power associated with these AGN-driven outflows is (22+/-9)*10^44 erg/s, and is sufficient to offset the cooling, indicating that AGN feedback still provides a viable solution to the cooling flow problem even in the strongest cool core clusters. Based on the distribution of the optical filaments, as well as a jet-like structure seen in the 325 MHz VLA radio map, we suggest that the cluster harbours older outflows along the north to south direction. The jet of the central AGN is therefore either precessing or sloshing-induced motions have caused the outflows to change directions. There are also hints of an X-ray depression to the north aligned with the 325 MHz jet-like structure, which might represent the highest redshift ghost cavity discovered to date. We further find evidence of a cold front (r=65kpc) that coincides with the outermost edge of the western X-ray cavity and the edge of the radio mini-halo. The common location of the cold front with the edge of the radio mini-halo supports the idea that the latter originates from electrons being reaccelerated due to sloshing induced turbulence. Alternatively, its coexistence with the edge of the X-ray cavity may be due to cool gas being dragged out by the outburst. We confirm that the central AGN is highly sub-Eddington and conclude that a >10^10M_Sun or a rapidly spinning black hole is favoured to explain both the radiative-inefficiency of the AGN and the powerful X-ray cavities.Comment: Accepted for publication to ApJ (minor corrections), 16 pages, 16 figures, 5 tables. Full resolution at http://www.stanford.edu/~juliehl/M1532

Different cell populations are inducible by BMP-2 covalently covered Bioverit® II implants in rabbit subcutis and middle ear

To optimize the function of implants the formation of surrounding connective tissue should be adapted in dependence to the mechanical conditions. Therefore, with nanostructured silica coated Bioverit® II implants were only partly reacted with recombinant BMP-2. The histology was compared 28, 84 and 301 days after implantation in the rabbit middle ear and subcutis, respectively. The whole tissue blocks were embedded in Epon, sequentially grinded, stained with Toluidine Blue O and Eosin G. The granulation tissue covering the implants varies related to cell types, cell amounts, extracellular matrix and vessels. Whereas the high cell density and the angiogenesis predominated in the subcutis, the formation of new bone could only be recognized in the scar around the implants in the middle ear.SFB/599/project D1

Diurnal pattern of QTc interval: How long is prolonged? Possible relation to circadian triggers of cardiovascular events

Objectives.This study sought to evaluate the range and variability of the QT and corrected QT (QTc) intervals over 24 h and to assess their pattern and relation to heart rate variability.Background.Recent Holter monitoring data have revealed a high degree of daily variability in the QTc interval. The pattern of this variability and its relation to heart rate variability remain poorly characterized.Methods.We developed and validated a new method for continuous measurement of QT intervals from three-channel, 24-h Holter recordings. Average RR, QT, QTc and heart rate variability were measured from 5-min segments of data from 21 healthy subjects.Results.Measurement of 6,048 segments showed mean (±SD) RR, QT and QTc intervals of 830 ± 100, 407 ± 23 and 445 ± 16 ms, respectively (mean QTc interval for men 434 ± 12 ms, 457 ± 10 ms for women, p < 0.0001). The average maximal QTc interval was 495 ± 21 ms and the average QTc range 95 ± 20 ms. The maximal QTc interval was ≥500 ms in 6 subjects and ≥490 ms in 13. The 95% upper confidence limit for the mean 24-h QTc interval was 452 ms (men 439 ms, women 461 ms). The RR, QT and QTc intervals and the high frequency component of heart rate variability were greater during sleep. Both the QTc interval and the variability between hourly minimal and maximal QTc intervals reached their circadian peak shortly after awakening, before declining to daytime levels.Conclusions.The maximal QTc interval over 24 h in normal subjects is longer than heretofore thought. Both QT and QTc intervals are longer during sleep. The QTc interval and QTc variability reach a peak shortly after awakening, which may reflect increased autonomic instability during early waking hours, and the time of the peak value corresponds in time to the period of reported increased vulnerability to ventricular tachycardia and sudden cardiac death. These findings have implications regarding the definition of QT prolongation and its use in predicting arrhythmias and sudden death

Male depression risk, psychological distress, and psychotherapy uptake: Validation of the German version of the male depression risk scale

Background Screening for depressive disorders in men may be complicated by traditional male role norms. The Male Depression Risk Scale (MDRS) was developed to aid screening for depression in men adhering to traditional male role norms and to facilitate identification of depression in men in general and to promote treatment uptake. Aims Validation of a German version of the MDRS and examination of its potential to predict clinical characteristics. Methods In an anonymous online survey comprising of 1605 participants (male: N = 671; 42%), information was obtained on psychological distress, diagnosed psychological disorders, psychotherapy and psychopharmacological treatment. Additional measures included a German version of the MDRS as further mental-health-related constructs. Results The German version of the MDRS showed good validity and reliability. The previously identified 6-factor structure could be replicated for the German version. Compared to the Patient Health Questionnaire 9, the MDRS showed similar detection performance in identifying men who self-reported psychological distress, psychological disorders, depression, psychotherapy usage, or usage of psychopharmacological therapy. Conclusions The German version of the MDRS shows good psychometric validity and represents a valid screening instrument for the identification of psychological distress specifically in men