Six-year mortality in a street-recruited cohort of homeless youth in San Francisco, California.

Objectives. The mortality rate of a street-recruited homeless youth cohort in the United States has not yet been reported. We examined the six-year mortality rate for a cohort of street youth recruited from San Francisco street venues in 2004. Methods. Using data collected from a longitudinal, venue-based sample of street youth 15-24 years of age, we calculated age, race, and gender-adjusted mortality rates. Results. Of a sample of 218 participants, 11 died from enrollment in 2004 to December 31, 2010. The majority of deaths were due to suicide and/or substance abuse. The death rate was 9.6 deaths per hundred thousand person-years. The age, race and gender-adjusted standardized mortality ratio was 10.6 (95% CI [5.3-18.9]). Gender specific SMRs were 16.1 (95% CI [3.3-47.1]) for females and 9.4 (95% CI [4.0-18.4]) for males. Conclusions. Street-recruited homeless youth in San Francisco experience a mortality rate in excess of ten times that of the states general youth population. Services and programs, particularly housing, mental health and substance abuse interventions, are urgently needed to prevent premature mortality in this vulnerable population

Nonlocal boundary conditions for corrugated acoustic metasurface with strong near field interactions

The propagation of long-wavelength sound in the presence of a metasurface made by arranging acoustic resonators periodically upon or slightly above an impervious substrate is studied. The method of two-scale asymptotic homogenization is used to derive effective boundary conditions, which account for both the surface corrugation and the low-frequency resonance. This method is applied to periodic arrays of resonators of any shape operating in the long-wavelength regime. The approach relies on the existence of a locally periodic boundary layer developed in the vicinity of the metasurface, where strong near-field interactions of the resonators with each other and with the substrate take place. These local effects give rise to an effective surface admittance supplemented by nonlocal contributions from the simple and double gradients of the pressure at the surface. These phenomena are illustrated for the periodic array of cylindrical Helmholtz resonators with an extended inner duct. Effects of the centre-to-centre spacing and orientation of the resonators' opening on the nonlocality and apparent resonance frequency are studied. The model could be used to design metasurfaces with specific effective boundary conditions required for particular applications

Patient volumes and pre- and postdischarge postpartum infection: A retrospective cohort study

BackgroundTo examine the association between hospital and clinician obstetric volume and postpartum infection risk in the pre- and postdischarge periods.MethodsWe used data from the 2011 New York State Inpatient and Emergency Department Databases to fit generalized estimating equation models to examine the effect of hospital and clinician obstetric volume on infection before discharge and in the 30 days after discharge after delivery.ResultsHigher clinician volume was associated with lower predischarge infection risk (odds ratio [OR] for first vs third quartile was 0.84; 95% confidence interval [CI], 0.77-0.98). There was an uncertain trend toward higher predischarge infection risk in higher volume hospitals (OR for first vs third quartile was 1.36; 95% CI, 0.79-2.34). We found no associations between patient volumes and postdischarge infections; however, power was insufficient to rule out small associations. The joint association of hospital and clinician volumes with postdischarge infection appeared submultiplicative (product term OR = 0.95; 95% CI, 0.92-0.98).ConclusionThis study adds to the evidence that hospital obstetric volume is positively associated with predischarge postpartum infections, whereas clinician volume may be negatively associated with those predischarge infections. The associations between hospital obstetric volume and postdischarge infection appear to differ. These results underscore the importance of including postdischarge follow-up in hospital-based studies of postpartum infection

Patient volumes and pre- and postdischarge postpartum infection: A retrospective cohort study.

BackgroundTo examine the association between hospital and clinician obstetric volume and postpartum infection risk in the pre- and postdischarge periods.MethodsWe used data from the 2011 New York State Inpatient and Emergency Department Databases to fit generalized estimating equation models to examine the effect of hospital and clinician obstetric volume on infection before discharge and in the 30 days after discharge after delivery.ResultsHigher clinician volume was associated with lower predischarge infection risk (odds ratio [OR] for first vs third quartile was 0.84; 95% confidence interval [CI], 0.77-0.98). There was an uncertain trend toward higher predischarge infection risk in higher volume hospitals (OR for first vs third quartile was 1.36; 95% CI, 0.79-2.34). We found no associations between patient volumes and postdischarge infections; however, power was insufficient to rule out small associations. The joint association of hospital and clinician volumes with postdischarge infection appeared submultiplicative (product term OR = 0.95; 95% CI, 0.92-0.98).ConclusionThis study adds to the evidence that hospital obstetric volume is positively associated with predischarge postpartum infections, whereas clinician volume may be negatively associated with those predischarge infections. The associations between hospital obstetric volume and postdischarge infection appear to differ. These results underscore the importance of including postdischarge follow-up in hospital-based studies of postpartum infection