Virialization of Galaxy Clusters and Beyond

Using samples of structures identified by a multi-scale decomposition from numerical simulation, we analyze the scale-dependence of the virialization of clusters. We find that beyond the scale of full virialization there exists a radius range over which clusters are quasi-virialized, i.e. while the internal structure of an {\it individual} cluster is at substantial departure from dynamical relaxation, some {\it statistical} properties of the multi-scale identified clusters are approximately the same as those for the virialized systems. The dynamical reason of the existence of quasi-virialization is that some of the scaling properties of dynamically relaxed systems of cosmic gravitational clustering approximately hold beyond the full virialization regime. The "individual-statistical" duality of the quasi-virialization provides an explanation of the observed puzzle that the total masses of clusters derived from virial theorem are statistically the same as the gravitational lensing determined masses, in spite of the presence of irregular configuration and substructures in individual clusters. It also explains the tight correlation between the velocity dispersion of optical galaxies and the temperature of X-ray emitting gas. Consequently, the virial mass estimators based on the assumptions of isothermal and hydrostatic model are statistically applicable to scales on which the clusters are quasi-virialized. In the quasi-virialization regime, the temperature functions of clusters also show scaling. This feature is a useful discriminator among cosmological models.Comment: AAS Latex file, 22 pages+ 14 figures, accepted for publication in Ap

Glimpsing through the high redshift neutral hydrogen fog

We analyze the transmitted flux in a sample of 17 QSOs spectra at 5.74<zem<6.42 to obtain tighter constraints on the volume-averaged neutral hydrogen fraction, xHI, at z~6. We study separately the narrow transmission windows (peaks) and the wide dark portions (gaps) in the observed absorption spectra. By comparing the statistics of these spectral features with Lyalpha forest simulations, we conclude that xHI evolves smoothly from 10^{-4.4} at z=5.3 to 10^{-4.2} at z=5.6, with a robust upper limit xHI<0.36 at z=6.3. The frequency and physical sizes of the peaks imply an origin in cosmic underdense regions and/or in HII regions around faint quasars or galaxies. In one case (the intervening HII region of the faint quasar RD J1148+5253 at z=5.70 along the LOS of SDSS J1148+5251 at z=6.42) the increase of the peak spectral density is explained by the first-ever detected transverse proximity effect in the HI Lyalpha forest; this indicates that at least some peaks result from a locally enhanced radiation field. We then obtain a strong lower limit on the foreground QSO lifetime of tQ>11 Myr. The observed widths of the peaks are found to be systematically larger than the simulated ones. Reasons for such discrepancy might reside either in the photoionization equilibrium assumption or in radiative transfer effects.Comment: 12 pages, 9 figures, revised to match the accepted version including a detailed analysis of the foreground QSO redshift and of the relativistic effects on the HII region shape; MNRAS in pres

Observations of SN 2017ein Reveal Shock Breakout Emission and A Massive Progenitor Star for a Type Ic Supernova

We present optical and ultraviolet observations of nearby type Ic supernova SN 2017ein as well as detailed analysis of its progenitor properties from both the early-time observations and the prediscovery Hubble Space Telescope (HST) images. The optical light curves started from within one day to $\sim$275 days after explosion, and optical spectra range from $\sim$2 days to $\sim$90 days after explosion. Compared to other normal SNe Ic like SN 2007gr and SN 2013ge, \mbox{SN 2017ein} seems to have more prominent C{\footnotesize II} absorption and higher expansion velocities in early phases, suggestive of relatively lower ejecta mass. The earliest photometry obtained for \mbox{SN 2017ein} show indications of shock cooling. The best-fit obtained by including a shock cooling component gives an estimate of the envelope mass as $\sim$0.02 M$_{\odot}$ and stellar radius as 8$\pm$4 R$_{\odot}$. Examining the pre-explosion images taken with the HST WFPC2, we find that the SN position coincides with a luminous and blue point-like source, with an extinction-corrected absolute magnitude of M$_V$$\sim$$-$8.2 mag and M$_I$$\sim$$-$7.7 mag.Comparisons of the observations to the theoretical models indicate that the counterpart source was either a single WR star or a binary with whose members had high initial masses, or a young compact star cluster. To further distinguish between different scenarios requires revisiting the site of the progenitor with HST after the SN fades away.Comment: 28 pages, 19 figures; accepted for publication in The Astrophysical Journa

Determinants of cord care practices among mothers in Benin City, Edo State, Nigeria

Background: Mothers care for their infants&#8217; umbilical cord stump in various ways. Different cord care practices have been documented; some are beneficial while others are harmful. Who and what influence the cord care practiced by mothers have, however, not been fully explored particularly in the study locale.Objective: The objective of this study was to determine the factors that influence cord care practices among mothers in Benin City.Materials and Methods: The study subjects included 497 mothers who brought their babies to Well Baby/Immunization Clinic at the University of Benin Teaching Hospital (UBTH), Benin City, Edo State, between July and August 2009. A structured questionnaire served as an instrument to extract information on their biodata and possible determinants of cord care practices.Results: Significantly older women (P=0.023), educated mothers (P=0.029), and those who had male babies (P=0.013) practiced beneficial cord stump care practices. Beneficial cord care practice increased with increasing maternal educational status. The best predictors of beneficial cord care practices are maternal level of education (P=0.029) and infant&#8217;s sex (P=0.013). The use of harmful cord care practices was more common among mothers who delivered outside the Teaching hospitals. Most (71.2%) of the mothers were aware of hygienic/beneficial cord care. The choices of cord care methods eventually practiced by mothers were influenced mainly by the disposition of nurses (51.3%), participants&#8217; mothers (32.0%), and their mothers&#8209;in&#8209;law (5.8%). There was no significant relationship between cord care practice on one hand and maternal parity, tribe, and socioeconomic classes on the other.Conclusion/Recommendation: The need for female education is again emphasized. The current findings strongly justify the need for public enlightenment programs, using the mass media and health talks in health facilities, targeting not only women of reproductive age but also secondary audience like their mothers, mothers&#8209;in&#8209;law, nurses, and attendants at health facilities. Proper hygiene including proper hand washing techniques while caring for newborns along with vaccination of infants and their mothers will help prevent infections including tetanus while prompt health&#8209;seeking behavior is advised to improve outcome should such infections occur

Cord care practices among mothers attending immunization clinic at the University of Benin Teaching Hospital, Benin City.

Background: Poor cord care practices contribute to neonatal morbidity and mortality resulting from neonatal infections including tetanus. Identification of negative practices should ultimately improve care and neonatal outcome. Objective: To evaluate cord care practices among mothers attending the Well Baby/Immunization Clinic of the University of Benin Teaching Hospital (UBTH), Benin City. Subjects and Methods: Four hundred and ninety-seven mothers who brought their babies to Well Baby/Immunization Clinic in UBTH between July and August 2009 were interviewed. A structured, pretested questionnaire was used as test instrument to investigate the care of the umbilical cord of their infants in their last deliveries. Results: Harmful or non-beneficial cord care practices were common (79.5%) among mothers in Benin City. Most delivery units used thread (65.6%) and plastic cord clamp (22.7%) to secure haemostasis at the umbilical stump. Other materials used include suture materials, strips of cloth, bandage, plaster and rubber band. Majority of the mothers practiced hand washing before (86.9%) and after (89.3%) cord care. The traditional practices of cord care in Benin City include the use of hot compress (46.1%), menthol-containing balm, herbs, native chalk, petroleum jelly, palm oil, toothpaste (Close-up), salt, sand and saliva. The most common single agent for cord treatment was alcohol (methylated spirit). Conclusion: The attendant risks associated with harmful cord care practices remain real in our communities. There is need for&nbsp; education of the public, using the mass media and health talks in health facilities, to discourage harmful cord care practices while reinforcing beneficial ones.Key Words: Umbilical cord, Care practices, Mothers, Benin City. Introductio

Annexin-A5 assembled into two-dimensional arrays promotes cell membrane repair

Eukaryotic cells possess a universal repair machinery that ensures rapid resealing of plasma membrane disruptions. Before resealing, the torn membrane is submitted to considerable tension, which functions to expand the disruption. Here we show that annexin-A5 (AnxA5), a protein that self-assembles into two-dimensional (2D) arrays on membranes upon Ca2+ activation, promotes membrane repair. Compared with wild-type mouse perivascular cells, AnxA5-null cells exhibit a severe membrane repair defect. Membrane repair in AnxA5-null cells is rescued by addition of AnxA5, which binds exclusively to disrupted membrane areas. In contrast, an AnxA5 mutant that lacks the ability of forming 2D arrays is unable to promote membrane repair. We propose that AnxA5 participates in a previously unrecognized step of the membrane repair process: triggered by the local influx of Ca2+, AnxA5 proteins bind to torn membrane edges and form a 2D array, which prevents wound expansion and promotes membrane resealing

A tuberculosis nationwide prevalence survey in Gambia, 2012.

OBJECTIVE: To estimate the population prevalence of active pulmonary tuberculosis in Gambia. METHODS: Between December 2011 and January 2013, people aged ≥ 15 years participating in a nationwide, multistage cluster survey were screened for active pulmonary tuberculosis with chest radiography and for tuberculosis symptoms. For diagnostic confirmation, sputum samples were collected from those whose screening were positive and subjected to fluorescence microscopy and liquid tuberculosis cultures. Multiple imputation and inverse probability weighting were used to estimate tuberculosis prevalence. FINDINGS: Of 100 678 people enumerated, 55 832 were eligible to participate and 43 100 (77.2%) of those participated. A majority of participants (42 942; 99.6%) were successfully screened for symptoms and by chest X-ray. Only 5948 (13.8%) were eligible for sputum examination, yielding 43 bacteriologically confirmed, 28 definite smear-positive and six probable smear-positive tuberculosis cases. Chest X-ray identified more tuberculosis cases (58/69) than did symptoms alone (43/71). The estimated prevalence of smear-positive and bacteriologically confirmed pulmonary tuberculosis were 90 (95% confidence interval, CI: 53-127) and 212 (95% CI: 152-272) per 100 000 population, respectively. Tuberculosis prevalence was higher in males (333; 95% CI: 233-433) and in the 35-54 year age group (355; 95% CI: 219-490). CONCLUSION: The burden of tuberculosis remains high in Gambia but lower than earlier estimates of 490 per 100 000 population in 2010. Less than half of all cases would have been identified based on smear microscopy results alone. Successful control efforts will require interventions targeting men, increased access to radiography and more accurate, rapid diagnostic tests

A case of congenital unilateral absence of the vas deferens

Background Congenital unilateral absence of the vas deferens occurs in 0.5%–1.0% of males. It has been associated with various genitourinary abnormalities, including renal agenesis. We report a case of congenital unilateral absence of the vas deferens found incidentally during vasectomy in a patient with known unilateral renal agenesis. Case presentation A 24-year-old male presented to our urology clinic requesting vasectomy. His past history was significant for left renal agenesis. Following successful right vasectomy, several attempts to locate the left vas deferens were unsuccessful. We diagnosed congenital unilateral absence of the vas deferens. Follow-up semen analysis showed azoospermia. Conclusion As vasectomies are increasingly performed in outpatient settings, it is imperative that physicians be aware of this condition, which can be recognized by a simple physical exam. Recognition could prevent unnecessary surgery and prompt providers to investigate for associated abnormalities

Large-scale structure in the Lyman-alpha forest II: analysis of a group of ten QSOs

The spatial distribution of Ly-alpha forest absorption systems towards ten QSOs has been analysed to search for large-scale structure over the redshift range 2.2 < z < 3.4. The QSOs form a closely spaced group on the sky and are concentrated within a 1 deg^2 field. We have employed a technique based on the first and second moments of the transmission probability density function which is capable of identifying and assessing the significance of regions of over- or underdense Ly-alpha absorption. We find evidence for large-scale structure in the distribution of Ly-alpha forest absorption at the > 99 per cent confidence level. In individual spectra we find overdense Ly-alpha absorption on scales of up to 1200 km s^-1. There is also strong evidence for correlated absorption across line of sight pairs separated by < 3 h^-1 proper Mpc (q_0 = 0.5). For larger separations the cross-correlation signal becomes progressively less significant.Comment: 15 pages, LaTeX, 6 Postscript figures, accepted for publication in MNRA