Metallicity Evolution of Damped Lyman-Alpha Galaxies

We have reanalyzed the existing data on Zinc abundances in damped Ly-alpha (DLA) absorbers to investigate whether their mean metallicity evolves with time. Most models of cosmic chemical evolution predict that the mass- weighted mean interstellar metallicity of galaxies should rise with time from a low value ~ 1/30 solar at z ~ 3 to a nearly solar value at z ~ 0. However, several previous analyses have suggested that there is little or no evolution in the global metallicity of DLAs. We have used a variety of statistical techniques to quantify the global metallicity-redshift relation and its uncertainties, taking into account both measurement and sampling errors. Three new features of our analysis are: (a) an unbinned N(H I)-weighted nonlinear chi-square fit to an exponential relation; (b) survival analysis to treat the large number of limits in the existing data; and (c) a comparison of the data with several models of cosmic chemical evolution based on an unbinned N(H I)-weighted chi-square. We find that a wider range of evolutionary rates is allowed by the present data than claimed in previous studies. The slope of the exponential fit to the N(H I)-weighted mean Zn metallicity vs. redshift relation is -0.20 plus minus 0.11 counting limits as detections and -0.27 plus minus 0.12 counting limits as zeros. Similar results are also obtained if the data are binned in redshift, and if survival analysis is used. These slopes are marginally consistent with no evolution, but are also consistent with the rates predicted by several models of cosmic chemical evolution. Finally, we outline some future measurements necessary to improve the statistics of the global metallicity-redshift relation.Comment: 25 pages, 1 figure, accepted for publication in the Astrophysical Journa

Rising incidence of hip fractures in Sindhudurg west coast of Maharashtra, South India (2000 to 2011)

Background: The incidence of hip fractures in Sindhudurg, west coast of Maharashtra has been reported in relation to age and gender.Methods: Using the medical records and X-ray registers from May 2000 to October 2011, all patients of proximal femoral fractures were recorded and included in this study. The data was cross checked doubly with details of indoor case papers against ward admission and operation theatre registers, were found to be congruent after verifying the names of patients.Results: The total male incidence was bimodal with moderate peaks at 31 to 50 years and very high at 51 to 70 years. The female incidence with peaks at 41 to 60 years with regular steady increase up to 80 years. Males of 31 to 70 years 2.5 times more likely to sustain a fracture (95% CI 2.3 to 2.8) than females. Females between 40 to 60 years 2.8 times more likely to sustain fracture than males (95% CI 2.5 to 3.0). The trend was stable from year to year. This high increase in hip fractures in men of 51 to 70 years incidence documented osteoporotic fractures in contrast with too much emphasis on the importance of menopause in hip fractures.Conclusions: Despite wide variations in age specific hip fracture rates over a decade, reasons for differences are not clear. From 2000 to 2011, the hip fractures in district hospital increased by a factor of 6.6%, 14.34% in both the genders above the age of 41 years in parallel with hospital admissions.

Magnetic properties and complex magnetic phase diagram in non centrosymmetric EuRhGe3_3 and EuIrGe3_3 single crystals

We report the magnetic properties of two Eu based compounds, single crystalline EuIrGe$_3$ and EuRhGe$_3$, inferred from magnetisation, electrical transport, heat capacity and $^{151}$Eu M\"{o}ssbauer spectroscopy. These previously known compounds crystallise in the non-centrosymmetric, tetragonal, $I4mm$, BaNiSn$_3$-type structure. Single crystals of EuIrGe$_3$ and EuRhGe$_3$ were grown using high temperature solution growth method using In as flux. EuIrGe$_3$ exhibits two magnetic orderings at $T_{\rm N1}$ = 12.4 K, and $T_{\rm N2}$ = 7.3 K. On the other hand EuRhGe$_3$ presents a single magnetic transition with a $T_{\rm N}$ = 12 K. $^{151}$Eu M\"{o}ssbauer spectra present evidence for a cascade of transitions from paramagnetic to incommensurate amplitude modulated followed by an equal moment antiferromagnetic phase at lower temperatures in EuIrGe$_3$, the transitions having a substantial first order character. On the other hand the $^{151}$Eu M\"{o}ssbauer spectra at 4.2 and 9 K in EuRhGe$_3$ present evidence of a single magnetic transition. In both compounds a superzone gap is observed for the current density $J\parallel$ [001], which enhances with transverse magnetic field. The magnetisation measured up to 14 T shows the occurrence of field induced transitions, which are well documented in the magnetotransport data as well. The magnetic phase diagram constructed from these data is complex, revealing the presence of many phases in the $H-T$ phase space