Ignition and Front Propagation in Polymer Electrolyte Membrane Fuel Cells

Water produced in a Polymer Electrolyte Membrane (PEM) fuel cell enhances membrane proton conductivity; this positive feedback loop can lead to current ignition. Using a segmented anode fuel cell we study the effect of gas phase convection and membrane diffusion of water on the spatiotemporal nonlinear dynamics - localized ignition and front propagation - in the cell. Co-current gas flow causes ignition at the cell outlet, and membrane diffusion causes the front to slowly propagate to the inlet; counter-current flow causes ignition in the interior of the cell, with the fronts subsequently spreading towards both inlets. These instabilities critically affect fuel cell performance

Axial Multicentric Osteosarcoma in an English Cocker Spaniel

No abstract available

Who is at risk of long hospital stay among patients admitted to geriatric acute care unit? Results from a prospective cohort study

1) To confirm that vitamin D deficiency, defined as serum 25-hydroxyvitamin D (25OHD) concentration < 25nmol/L, was associated with long length-of-stay (LOS) among older inpatients admitted to geriatric acute care unit; and 2) to examine which combination of risk factors of longer LOS including vitamin D deficiency best predicted longer LOS.Based on a prospective cohort study with a 25-day follow-up on average, 531 consecutive older inpatients (mean age 85.0 +/- 7.2 years, 59.1% women) admitted to the geriatric acute care unit of Angers University Hospital, France, were included. Linear regression models showed that male gender (P < 0.025), delirium (P < 0.015) and vitamin D deficiency (P < 0.001) were independently associated with a longer LOS. The highest risk of a longer LOS was shown while combining vitamin D deficiency with male gender (Odds ratio (OR)=3.70 with P < 0.001). The risk increased significantly while delirium was associated with these two baseline characteristics (OR=4.76 with P=0.001). Kaplan-Meier distributions of discharge differed significantly between participants who had or not the combination of the 3 criteria (P < 0.007). Vitamin D deficiency, delirium and male gender were significant risk factors for a longer LOS in the studied sample of older inpatients

Association between vitamin D deficiency and long hospital stay in geriatric acute care unit: results from a pilot cohort study

Finding a biomarker of long length-of-stay (LOS) would provide a simple solution to target frail older inpatients at such risk. The aim of this study was to determine whether serum 25-hydroxyvitamin D (25OHD) deficiency, defined as serum concentration <25 nmol/L, was associated with long LOS among inpatients admitted to a geriatric acute care unit. Three hundred and six older inpatients (mean age 84.6 +/- 6.4 years, 61.8 % women) were consecutively included in this longitudinal prospective cohort study. Patients were separated into two groups according to LOS tertiles: highest tertile (>= 14 days; n = 120) versus the other two tertiles combined (<14 days; n = 186). Serum 25OHD deficiency (58.3 vs. 38.7 %, P = 0.001) and the prevalence of male gender (58.3 vs. 28.5 %, P < 0.001) were higher among inpatients with the highest LOS compared with those with lower LOS. Serum 25OHD deficiency [odds ratio (OR) = 2.22, P = 0.001 for unadjusted model; OR = 1.87, P = 0.012 for fully adjusted model) and male gender (OR = 2.87, P < 0.001 for unadjusted model; OR = 2.64, P = 0.001 for full model) were associated with a high LOS. Vitamin D deficiency and male gender were risk factors for a long LOS in this pilot study. Using these risk factors to identify inpatients at risk of long LOS may be helpful in adapting early care plans, and thus improving inpatients\u27 health and shortening LOS

Association of Depressive Symptoms with Recurrent Falls: A Cross-Sectional Elderly Population Based Study and a Systematic Review

Background: Screening of depressive symptoms is recommended in recurrent fallers. Compared to the 30-item and 15-item Geriatric Depression Scales (GDS), the 4-item GDS is easier to administer and quicker to perform. The association between abnormal 4-item GDS score and recurrent falls has not yet been examined. In addition, while depressive symptoms-related gait instability is well known, the association with recurrent falls has been few studied. Objective: 1) To examine the association between abnormal 4-item GDS score and recurrent falls in community-dwelling older adults using original data from health examination centers (HEC) of French health insurance of Lyon, and 2) to perform a systematic review of studies that examined the association of depressive symptoms with recurrent falls among older adults. Methods: Firstly, based on a cross-sectional design, 2,594 community-dwellers (mean age 72.1 +/- 5.4years; 49.8% women) were recruited in HEC of Lyon, France. The 4-item GDS score (abnormal if score >= 1) and recurrent falls (i.e., 2 or more falls in the past year) were used as main outcomes. Secondly, a systematic English and French Medline literature search was conducted on May 28, 2012 with no limit of date using the following Medical Subject Heading (MeSH) terms "Aged OR aged, 80 and over", "Accidental falls", "Depressive disorder" and "Reccurence". The search also included the reference lists of the retrieved articles. Results: A total of 19.0% (n=494) participants were recurrent fillers in the cross-sectional study. Abnormal 4-item GDS score was more prevalent among recurrent fallers compared to non-recurrent fallers (44.7% versus 25.0%, with P<0.001), and was significantly associated with recurrent falls (Odd ratio (OR)=1.82 with P<0.001 for full model; OR=1.86 with P<0.001 for stepwise backward model). In addition to the current study, the systematic review found only four other studies on this topic, three of them examining the association of depressive symptoms with recurrent falls using 30-item or 15-item GDS. All studies showed a significant association of depressive symptoms with recurrent falls. Conclusions: The current cross-sectional study shows an association between abnormal 4-item GDS score and recurrent falls. This association of depressive symptoms with recurrent falls was confirmed by the systematic review. Based on these results, we suggest that recurrent falls risk assessment should involve a systematic screening of depressive symptoms using the 4-item GDS

Estimating the abundance of common dolphins on the southern coast of South Africa

Sightings made on an aerial survey in December 1982 and on a ship-based survey in January/February 1983 have been used to assess the size of the population of common dolphins (Delphinus capensis) occurring over the continental shelf south of South Africa. Thirteen sightings (12 primary) were made in 2,445.7 n. miles flown on the aerial survey and 10 sightings (6 primary) in 1,772.2 n. miles steamed on the ship-based survey. Sightings and effort in both surveys have been stratified by water depth (0-100 m, 100- 200 m) and geographical region (west coast, south coast). Because of difficulties in accurately estimating the size of schools in this highly gregarious species, numbers of individuals were counted in composite aerial photographs taken of the school. Radial distance and angle estimates to sightings from the ship were smeared to allow for estimation errors. Assuming g(0) = 1.0, both data sets resulted in roughly similar estimates of the number of schools (52-58 for aerial, 40-59 for ship-based across a range of sensitivity tests), but mean school size estimates differed significantly (454 SE 90 for aerial, 159 SE 27 for ship-based). As the aerial estimates were based on counts of animals in composite vertical photographs, they are considered more reliable than the ship-based estimates that were made from a lower vantage point and at a greater angle. Given the small number of primary sightings on each survey, it was considered preferable to produce a combined estimate using school density estimates from both surveys weighted by their inverse variances but applying the mean school size from the aircraft. The resultant population estimate of 49 schools (CV = 0.29) and 22200 individuals (CV = 0.35) is discussed in relation to known or estimated incidental mortalities in South African waters

Mobile Geriatric Team Advice: Effect on Length of Hospital Stay in Older Adults

International audienc

Serum vitamin D among geriatric inpatients: a biomarker of the severity of chronic diseases

International audienc

Why are some South African children with Down syndrom not being offered cardiac surgery?

About 1 in 1 000 children has Down syndrome. Extra chromosomal material results in a myriad of potential problems for the affected individual. About 40% of Down syndrome children will have cardiac abnormalities, ranging from the simple arterial duct to the complex atrioventricular septal defect. Virtually all these defects are amenable to surgical correction and extended survival is possible. In South Africa many of these children do not undergo cardiac surgery