Profiles of Dark Matter Velocity Anisotropy in Simulated Clusters

We report statistical results for dark matter (DM) velocity anisotropy, \beta, from a sample of some 6000 cluster-size halos (at redshift zero) identified in a \Lambda CDM hydrodynamical adaptive mesh refinement simulation performed with the Enzo code. These include profiles of \beta\ in clusters with different masses, relaxation states, and at several redshifts, modeled both as spherical and triaxial DM configurations. Specifically, although we find a large scatter in the DM velocity anisotropy profiles of different halos (across elliptical shells extending to at least ~$1.5 r_{vir}$), universal patterns are found when these are averaged over halo mass, redshift, and relaxation stage. These are characterized by a very small velocity anisotropy at the halo center, increasing outward to about 0.27 and leveling off at about $0.2 r_{vir}$. Indirect measurements of the DM velocity anisotropy fall on the upper end of the theoretically expected range. Though measured indirectly, the estimations are derived by using two different surrogate measurements - X-ray and galaxy dynamics. Current estimates of the DM velocity anisotropy are based on very small cluster sample. Increasing this sample will allow testing theoretical predictions, including the speculation that the decay of DM particles results in a large velocity boost. We also find, in accord with previous works, that halos are triaxial and likely to be more prolate when unrelaxed, whereas relaxed halos are more likely to be oblate. Our analysis does not indicate that there is significant correlation (found in some previous studies) between the radial density slope, \gamma, and \beta\ at large radii, $0.3 r_{vir} < r < r_{vir}$.Comment: 12 pages, 17 figures, accepted to Ap

The MgII Cross-section of Luminous Red Galaxies

We describe a search for MgII(2796,2803) absorption lines in Sloan Digital Sky Survey (SDSS) spectra of QSOs whose lines of sight pass within impact parameters of 200 kpc of galaxies with photometric redshifts of z=0.46-0.6 and redshift errors Delta z~0.05. The galaxies selected have the same colors and luminosities as the Luminous Red Galaxy (LRG) population previously selected from the SDSS. A search for Mg II lines within a redshift interval of +/-0.1 of a galaxy's photometric redshift shows that absorption by these galaxies is rare: the covering fraction is ~ 10-15% between 20 and 100 kpc, for Mg II lines with rest equivalent widths of Wr >= 0.6{\AA}, falling to zero at larger separations. There is no evidence that Wr correlates with impact parameter or galaxy luminosity. Our results are consistent with existing scenarios in which cool Mg II-absorbing clouds may be absent near LRGs because of the environment of the galaxies: if LRGs reside in high-mass groups and clusters, either their halos are too hot to retain or accrete cool gas, or the galaxies themselves - which have passively-evolving old stellar populations - do not produce the rates of star formation and outflows of gas necessary to fill their halos with Mg II absorbing clouds. In the rarer cases where Mg II is detected, however, the origin of the absorption is less clear. Absorption may arise from the little cool gas able to reach into cluster halos from the intergalactic medium, or from the few star-forming and/or AGN-like LRGs that are known to exist.Comment: Accepted by ApJ; minor correction

Expression of the H- and L-subunits of ferritin in bone marrow macrophages of patients with osteoarthritis

Osteoarthritis is a disease characterized by an increase in the production of reactive oxygen species (ROS) in afflicted joints. Excess iron, due to its role in the production of ROS and crystal deposition in the joints, is implicated in the disease progression of osteoarthritis. Ferritin is a major regulator of the bioavailability of iron, and its functions are determined largely by the combination of H- and L-subunits present in its outer protein shell. The purpose of the study was to investigate the expression of the H- and L-subunits of ferritin in bone marrow macrophages of osteoarthritis patients. The cytokine profiles were assessed as cytokines play an important role in the expression of the ferritin subunits. The H-subunit of ferritin in the bone marrow macrophages was significantly higher (P value = 0.035) in the osteoarthritis patients compared with the controls (107.84; 69.25–167.94 counts/μm2; n= 7 versus 71.07; 58.56–86.26 counts/μm2; n= 19). A marginally significant increase (P value = 0.059) was shown for the expression of the L-subunit in the osteoarthritis patients compared with the controls (133.03; 104.04–170.10 counts/μm2; n= 7 versus 104.23; 91.53–118.70 counts/μm2; n= 19). The osteoarthritis and control groups had comparable C-reactive protein, as well as proinflammatory and anti-inflammatory cytokine concentrations. The major exception was for transforming growth factor-β (TGF-β), which was higher (P value = 0.014) in the plasma of the osteoarthritis patients (16.69; 13.09–21.28 ng/mL; n= 7 versus 8.60; 6.34–11.67 ng/mL; n= 19). Up-regulation of the ferritin subunits decreases the levels of bioavailable iron and provides protection against the unwarranted production of ROS and crystal deposition. A role for TGF-β in the up-regulation of the expression of the H-subunit, and possibly the L-subunit, of ferritin is postulated in osteoarthritis.The Skye foundation and the University of Pretoria’s Postgraduate Mentor Bursary Programme.http://ebm.sagepub.comhb2017Physiolog

A Kennicutt-Schmidt Law for Intervening Absorption Line Systems

We argue that most strong intervening metal absorption line systems, where the rest equivalent width of the MgII 2796A line is >0.5A, are interstellar material in, and outflowing from, star-forming disks. We show that a version of the Kennicutt-Schmidt law is readily obtained if the MgII equivalent widths are interpreted as kinematic broadening from absorbing gas in outflowing winds originating from star-forming galaxies. Taking a phenomenological approach and using a set of observational constraints available for star-forming galaxies, we are able to account for the density distribution of strong MgII absorbers over cosmic time. The association of intervening material with star-forming disks naturally explains the metallicity and dust content of strong MgII systems as well as their high HI column densities, and does not require the advection of metals from compact star-forming regions into the galaxy halos to account for the observations. We find that galaxies with a broad range of luminosities can give rise to absorption of a given rest-equivalent width, and discuss possible observational strategies to better quantify true galaxy-absorber associations and further test our model. We show that the redshift evolution in the density of absorbers closely tracks the star formation history of the universe and that strong intervening systems can be used to directly probe the physics of both bright and faint galaxies over a broad redshift range. By identifying strong intervening systems with galaxy disks and quantifying a version of the Kennicutt-Schmidt law that applies to them, a new probe of the interstellar medium is found which provides complementary information to that obtained through emission studies of galaxies. Implications of our results for galaxy feedback and enrichment of the intergalactic medium are discussed. [abridged]Comment: 23 pages, 15 figure

Predictors for Adverse Outcome in Patients Aged 80 Years and Older Undergoing Emergent Hip Surgery

This find is registered at Portable Antiquities of the Netherlands with number PAN-0002908