We investigate the form and evolution of the X-ray luminosity-temperature (L
X-kT) relation of a sample of 114 galaxy clusters observed with Chandra at 0.1 < z < 1.3. The clusters were divided into ...subsamples based on their X-ray morphology or whether they host strong cool cores. We find that when the core regions are excluded, the most relaxed clusters (or those with the strongest cool cores) follow an L
X-kT relation with a slope that agrees well with simple self-similar expectations. This is supported by an analysis of the gas density profiles of the systems, which shows self-similar behaviour of the gas profiles of the relaxed clusters outside the core regions. By comparing our data with clusters in the Representative XMM-Newton Cluster Structure Survey (REXCESS) sample, which extends to lower masses, we find evidence that the self-similar behaviour of even the most relaxed clusters breaks at around 3.5 keV. By contrast, the L
X-kT slopes of the subsamples of unrelaxed systems (or those without strong cool cores) are significantly steeper than the self-similar model, with lower mass systems appearing less luminous and higher mass systems appearing more luminous than the self-similar relation. We argue that these results are consistent with a model of non-gravitational energy input in clusters that combines central heating with entropy enhancements from merger shocks. Such enhancements could extend the impact of central energy input to larger radii in unrelaxed clusters, as suggested by our data. We also examine the evolution of the L
X-kT relation, and find that while the data appear inconsistent with simple self-similar evolution, the differences can be plausibly explained by selection bias, and thus we find no reason to rule out self-similar evolution. We show that the fraction of cool core clusters in our (non-representative) sample decreases at z > 0.5 and discuss the effect of this on measurements of the evolution in the L
X-kT relation.
Background and purpose:
The endocannabinoid N‐arachidonoylethanolamide (anandamide) is co‐synthesized with other N‐acylethanolamides, namely N‐palmitoylethanolamide (PEA) and N‐oleoylethanolamide ...(OEA), which have been shown to potentiate anandamide responses (so‐called ‘entourage effects’) in non‐vascular tissues. It remains unclear whether such interactions occur in the circulation.
Experimental approach:
In rat isolated small mesenteric arteries, the effects of PEA and OEA on relaxation to anandamide and tissue contents of the N‐acylethanolamides were examined under myographic conditions.
Key results:
Anandamide‐induced relaxation was potentiated by pretreatment with PEA (10 μM) or OEA (1 μM), or in combination. The potentiation by PEA and OEA was endothelium‐independent and abolished by treatment with capsaicin (10 μM), which desensitizes the transient receptor potential vanilloid type 1 (TRPV1) receptor system, or by the TRPV1 receptor antagonist, N‐(3‐methoxyphenyl)‐4‐chlorocinnamide (SB366791) (2 μM). It was also observed at molar ratios of anandamide and PEA (or OEA) similar to those found in mesenteric arteries. PEA and inhibition of anandamide hydrolysis by 3′‐carbamoyl‐biphenyl‐3‐yl‐cyclohexylcarbamate (URB597) (1 μM) additively potentiated anandamide responses. On the other hand, PEA and OEA also induced vasorelaxation per se (rank order of potency: anandamide>OEA>PEA), but relaxation to the three N‐acylethanolamides displayed different sensitivity to treatment with capsaicin, SB366791 and URB597. For example, relaxations to anandamide and OEA, but not PEA, were attenuated by both capsaicin and SB366791.
Conclusion and implications:
This study shows that PEA and OEA potentiate relaxant responses to anandamide through TRPV1 receptors in rat small mesenteric arteries. The congeners also induce vasorelaxation per se, suggesting a function for the N‐acylethanolamides in vascular control.
British Journal of Pharmacology (2008) 155, 837–846; doi:10.1038/bjp.2008.324; published online 11 August 2008
The molecular circadian clocks in the mammalian retina are locally synchronized by environmental light cycles independent of the suprachiasmatic nuclei (SCN) in the brain. Unexpectedly, this ...entrainment does not require rods, cones, or melanopsin (OPN4), possibly suggesting the involvement of another retinal photopigment. Here, we show that the ex vivo mouse retinal rhythm is most sensitive to short-wavelength light but that this photoentrainment requires neither the short-wavelength–sensitive cone pigment S-pigment or cone opsin (OPN1SW) nor encephalopsin (OPN3). However, retinas lacking neuropsin (OPN5) fail to photoentrain, even though other visual functions appear largely normal. Initial evidence suggests that OPN5 is expressed in select retinal ganglion cells. Remarkably, the mouse corneal circadian rhythm is also photoentrainable ex vivo, and this photoentrainment likewise requires OPN5. Our findings reveal a light-sensing function for mammalian OPN5, until now an orphan opsin.
We present results from new Chandra, GMRT, and SOAR observations of NGC 5813, the dominant central galaxy in a nearby galaxy group. The system shows three pairs of collinear cavities at 1 kpc, 8 kpc, ...and 20 kpc from the central source, from three distinct outbursts of the central active galactic nucleus (AGN), which occurred 3 X 106, 2 X 107, and 9 X 107 yr ago. The H Delta *a and X-ray observations reveal filaments of cool gas that has been uplifted by the X-ray cavities. The inner two cavity pairs are filled with radio-emitting plasma, and each pair is associated with an elliptical surface brightness edge, which we unambiguously identify as shocks (with measured temperature jumps) with Mach numbers of M 1.7 and M 1.5 for the inner and outer shocks, respectively. Such clear signatures from three distinct AGN outbursts in an otherwise dynamically relaxed system provide a unique opportunity to study AGN feedback and outburst history. The mean power of the two most recent outbursts differs by a factor of six, from (1.5-10)X1042 erg s--1, indicating that the mean jet power changes significantly over long (~107 yr) timescales. The total energy output of the most recent outburst is also more than an order of magnitude less than the total energy of the previous outburst (1.5 X 1056 erg versus 4 X 1057 erg), which may be a result of the lower mean power, or may indicate that the most recent outburst is ongoing. The outburst interval implied by both the shock and cavity ages (~107 yr) indicates that, in this system, shock heating alone is sufficient to balance radiative cooling close to the central AGN, which is the relevant region for regulating feedback between the intracluster medium and the central supermassive black hole.
Cluster mergers leave distinct signatures in the intracluster medium (ICM) in the form of shocks and diffuse cluster radio sources that provide evidence for the acceleration of relativistic ...particles. However, the physics of particle acceleration in the ICM is still not fully understood. Here we present new 1-4 GHz Jansky Very Large Array (VLA) and archival Chandra observations of the HST Frontier Fields Cluster Abell 2744. In our new VLA images, we detect the previously known ∼2.1 Mpc radio halo and ∼1.5 Mpc radio relic. We carry out a radio spectral analysis from which we determine the relic's injection spectral index to be . This corresponds to a shock Mach number of under the assumption of diffusive shock acceleration. We also find evidence for spectral steepening in the post-shock region. We do not find evidence for a significant correlation between the radio halo's spectral index and ICM temperature. In addition, we observe three new polarized diffuse sources and determine two of these to be newly discovered giant radio relics. These two relics are located in the southeastern and northwestern outskirts of the cluster. The corresponding integrated spectral indices measure −1.81 0.26 and −0.63 0.21 for the SE and NW relics, respectively. From an X-ray surface brightness profile we also detect a possible density jump of co-located with the newly discovered SE relic. This density jump would correspond to a shock front Mach number of .
We present a multiwavelength study of the massive galaxy cluster Abell 1763 at redshift z = 0.231. Image analysis of a 19.6 ks Chandra archival observation reveals a cluster-wide spiral of enhanced ...surface brightness in the intracluster medium (ICM). While such spirals are understood to form in clusters with sloshing strong cool cores (SCCs), the gas comprising the spiral's apex is of intermediate entropy (∼110 keV cm2) and cooling time (∼6.8 Gyr), indicating core disruption is occurring throughout the spiral formation process. Two subclusters dominated by the second- and third-ranked galaxies in the system lie along a line parallel to the elongation axis of the primary cluster's ICM. Both subsystems appear to have fallen in along a previously discovered intercluster filament and are each considered candidates as the perturber responsible for initiating disruptive core sloshing. Dynamical analysis indicates infall is occurring with a relative radial velocity of ∼1800 km s−1. The brightest cluster galaxy of Abell 1763 possesses a high line-of-sight peculiar velocity (vpec ∼ 650 km s−1) and hosts a powerful (P1.4 ∼ 1026 W Hz−1) bent double-lobed radio source, likely shaped by the relative bulk ICM flow induced in the merger. The cluster merger model of SCC destruction invokes low impact parameter infall as the condition required for core transformation. In contrast to this, the high angular momentum event occurring in Abell 1763 suggests that off-axis mergers play a greater role in establishing the non-cool core cluster population than previously assumed.
ABSTRACT We present results from a very deep (650 ks) Chandra X-ray observation of the galaxy group NGC 5813, the deepest Chandra observation of a galaxy group to date. This system uniquely shows ...three pairs of collinear cavities, with each pair associated with an unambiguous active galactic nucleus (AGN) outburst shock front. The implied mean kinetic power is roughly the same for each outburst, demonstrating that the average AGN kinetic luminosity can remain stable over long timescales (∼50 Myr). The two older outbursts have larger, roughly equal total energies as compared with the youngest outburst, implying that the youngest outburst is ongoing. We find that the gas radiative cooling rate and mean shock heating rate are well balanced at each shock front, suggesting that shock heating alone is sufficient to offset cooling and establish AGN/intracluster medium (ICM) feedback within at least the central 30 kpc. This heating takes place roughly isotropically and most strongly at small radii, as is required for feedback to operate. We suggest that shock heating may play a significant role in AGN feedback at smaller radii in other systems, where weak shocks are more difficult to detect. We find non-zero shock front widths that are too large to be explained by particle diffusion. Instead, all measured widths are consistent with shock broadening due to propagation through a turbulent ICM with a mean turbulent speed of ∼70 km s−1. Finally, we place lower limits on the temperature of any volume-filling thermal gas within the cavities that would balance the internal cavity pressure with the external ICM.
We present Atacama Large Millimeter/submillimeter Array and Multi-Unit Spectroscopic Explorer observations of the brightest cluster galaxy in Abell 2597, a nearby (z = 0.0821) cool core cluster of ...galaxies. The data map the kinematics of a three billion solar mass filamentary nebula that spans the innermost 30 kpc of the galaxy's core. Its warm ionized and cold molecular components are both cospatial and comoving, consistent with the hypothesis that the optical nebula traces the warm envelopes of many cold molecular clouds that drift in the velocity field of the hot X-ray atmosphere. The clouds are not in dynamical equilibrium, and instead show evidence for inflow toward the central supermassive black hole, outflow along the jets it launches, and uplift by the buoyant hot bubbles those jets inflate. The entire scenario is therefore consistent with a galaxy-spanning "fountain," wherein cold gas clouds drain into the black hole accretion reservoir, powering jets and bubbles that uplift a cooling plume of low-entropy multiphase gas, which may stimulate additional cooling and accretion as part of a self-regulating feedback loop. All velocities are below the escape speed from the galaxy, and so these clouds should rain back toward the galaxy center from which they came, keeping the fountain long lived. The data are consistent with major predictions of chaotic cold accretion, precipitation, and stimulated feedback models, and may trace processes fundamental to galaxy evolution at effectively all mass scales.
Objectives: To examine 397 strains of Salmonella enterica of human and animal origin comprising 35 serotypes for the presence of aadB, aphAI-IAB, aadA1, aadA2, bla(Carb2) or pse1, bla(Tem), cat1, ...cat2, dhfr1, floR, strA, sul1, sul2, tetA(A), tetA(B) and tetA(G) genes, the presence of class 1 integrons and the relationship of resistance genes to integrons and antibiotic resistance. Results: Some strains were resistant to ampicillin (91), chloramphenicol (85), gentamicin (2), kanamycin (14), spectinomycin (81), streptomycin (119), sulfadiazine (127), tetracycline (108) and trimethoprim (45); 219 strains were susceptible to all antibiotics. bla(Carb2), floR and tetA(G) genes were found in S. Typhimurium isolates and one strain of S. Emek only. Class 1 integrons were found in S. Emek, Haifa, Heidelberg, Mbandaka, Newport, Ohio, Stanley, Virchow and in Typhimurium, mainly phage types DT104 and U302. These strains were generally multi-resistant to up to seven antibiotics. Resistance to between three and six antibiotics was also associated with class 1 integron-negative strains of S. Binza, Dublin, Enteritidis, Hadar, Manhattan, Mbandaka, Montevideo, Newport, Typhimurium DT193 and Virchow. Conclusion: The results illustrate specificity of some resistance genes to S. Typhimurium or non- S. Typhimurium serotypes and the involvement of both class 1 integron and non-class 1 integron associated multi-resistance in several serotypes. These data also indicate that the bla(Carb2), floR and tetA(G) genes reported in the SG1 region of S. Typhimurium DT104, U302 and some other serotypes are still predominantly limited to S. Typhimurium strains.
There is limited data pertaining to the risk of End Stage Renal Disease (ESRD) after living kidney donation. The Organ Procurement and Transplantation Network and the Center for Medicare and Medicaid ...Services databases were used to identify living kidney donors (LKDs) who subsequently developed ESRD and to calculate LKD ESRD rates. We found 126 cases of ESRD among 56 458 LKDs (0.22%) who donated during October 1, 1987–March 31, 2003. The overall LKD ESRD rate was 0.134 per 1000 years at risk, with an average duration of follow‐up of 9.8 years. ESRD rates for LKDs overall and for Black, White, male and female donors compared favorably to the ESRD incidence in the general population. The LKD ESRD rate was nearly five times higher for Blacks than for Whites and two times higher for males than females. However, these ethnic and gender‐related differences were similar to those previously reported for ESRD in the general population. Our findings do not show an increase in the risk of ESRD for LKDs and support the current practice of living kidney donation. Further research is needed to determine if improved donor screening or follow‐up will reduce the risk of postdonation ESRD.
This study utilizes the OPTN and CMS databases to demonstrate that although the ESRD rates after living kidney donation are higher for Black compared to White donors and for male compared to female donors, these ethnic‐ and gender‐related differences compare favorably to those reported in the general population. See editorial by Srinivas on page 1656.
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