Methods for estimating the case fatality ratio for a novel, emerging infectious disease.

During the course of an epidemic of a potentially fatal disease, it is important that the case fatality ratio be well estimated. The authors propose a novel method for doing so based on the Kaplan-Meier survival procedure, jointly considering two outcomes (death and recovery), and evaluate its performance by using data from the 2003 epidemic of severe acute respiratory syndrome in Hong Kong, People's Republic of China. They compare this estimate obtained at various points in the epidemic with the case fatality ratio eventually observed; with two commonly quoted, naïve estimates derived from cumulative incidence and mortality statistics at single time points; and with estimates in which a parametric mixture model is used. They demonstrate the importance of patient characteristics regarding outcome by analyzing subgroups defined by age at admission to the hospital

Influence of southern hemispheric biomass burning on midtropospheric distributions of nonmethane hydrocarbons and selected halocarbons over the remote South Pacific

Aircraft measurements of nonmethane hydrocarbons (NMHCs) and halocarbons were made over the remote South Pacific Ocean during late August-early October 1996 for NASA's Global Tropospheric Experiment (GTE) Pacific Exploratory Mission-Tropics A (PEM-Tropics A). This paper discusses the large-scale spatial distributions of selected trace gases encountered during PEM-Tropics A. The PEM-Tropics A observations are compared to measurements made over the southwestern pacific in early November 1995 as part of Aerosol Characterization Experiment (ACE 1). Continental pollution in the form of layers containing elevated levels of O3 was observed during a majority of PEM-Tropics flights, as well as during several ACE 1 flights. The chemical composition of these air masses indicates that they were not fresh and were derived from nonurban combustion sources. The substantial impact of biomass burning on the vertical structure of the South Pacific troposphere is discussed. Copyright 1999 by the American Geophysical Union

Impact of computer experience on the viability and repeatability of the Moorfields Motion Displacement Test (MMDT) in a developing and underserved African setting.

Background: The current study was designed to explore the effect of computer experience on the viability and testretest repeatability of the Moorfields Motion Displacement Test (MMDT), a novel computer-driven glaucoma screening device, in an African community setting. Methods: 164 healthy subjects were recruited from a semi-rural Mozambican environment, and stratified according to computer experience (computer naïve: n=85, computer familiar: n=79). A suprathreshold screening test algorithm was employed, and the global probability of true damage (GPTD), testing time (TT) and false positive (FP) response rate were recorded. The visual field test was conducted twice on the same eye, and results compared to determine intra-sessional repeatability. Results: No inter-group differences in GPTD or TT (p\u3e0.05) were observed between computer subgroups, although FP response rate was significantly higher among computer naïve subjects (p=0.00 for both tests). No inter-sessional differences were observed for GPTD, TT and FP (p\u3e0.05 for all) for either subgroup. A statistically significant positive correlation was found between repeat GPTD, TT and FP measures for all subgroups (

Direct and generative retrieval of autobiographical memories: The roles of visual imagery and executive processes.

Two experiments used a dual task methodology to investigate the role of visual imagery and executive resources in the retrieval of specific autobiographical memories. In Experiment 1, dynamic visual noise led to a reduction in the number of specific memories retrieved in response to both high and low imageability cues, but did not affect retrieval times. In Experiment 2, irrelevant pictures reduced the number of specific memories but only in response to low imageability cues. Irrelevant pictures also increased response times to both high and low imageability cues. The findings are in line with previous work suggesting that disrupting executive resources may impair generative, but not direct, retrieval of autobiographical memories. In contrast, visual distractor tasks appear to impair access to specific autobiographical memories via both the direct and generative retrieval routes, thereby highlighting the potential role of visual imagery in both pathways

How early can myocardial iron overload occur in Beta thalassemia major?

BACKGROUND: Myocardial siderosis is the most common cause of death in patients with beta thalassemia major(TM). This study aimed at investigating the occurrence, prevalence and severity of cardiac iron overload in a young Chinese population with beta TM. METHODS AND RESULTS: We analyzed T2* cardiac magnetic resonance (CMR), left ventricular ejection fraction (LVEF) and serum ferritin (SF) in 201 beta TM patients. The median age was 9 years old. Patients received an average of 13 units of blood per year. The median SF level was 4536 ng/ml and 165 patients (82.1%) had SF>2500 ng/ml. Myocardial iron overload was detected in 68 patients (33.8%) and severe myocardial iron overload was detected in 26 patients (12.6%). Twenty-two patients ≤10 years old had myocardial iron overload, three of whom were only 6 years old. No myocardial iron overload was detected under the age of 6 years. Median LVEF was 64% (measured by CMR in 175 patients). Five of 6 patients with a LVEF<56% and 8 of 10 patients with cardiac disease had myocardial iron overload. CONCLUSIONS: The TM patients under follow-up at this regional centre in China patients are younger than other reported cohorts, more poorly-chelated, and have a high burden of iron overload. Myocardial siderosis occurred in patients younger than previously reported, and was strongly associated with impaired LVEF and cardiac disease. For such poorly-chelated TM patients, our data shows that the first assessment of cardiac T2* should be performed as early as 6 years old

Doses of neighborhood nature: the benefits for mental health of living with nature

This is the author accepted manuscript. The final version is available from OUP via the DOI in this record.Experiences of nature provide many mental health benefits, particularly for people living in urban areas. The natural characteristics of city residents’ neighborhoods are likely to be critical determinants of the daily nature dose that they receive, however which characteristics are important remains unclear. One possibility is that the greatest benefits are provided by characteristics that are most visible during the day and so most likely to be experienced by people. We demonstrate that of five neighborhood nature characteristics tested, vegetation cover and afternoon bird abundances were positively associated with a lower prevalence of depression, anxiety and stress. Further, dose-response modelling shows a threshold response where the population prevalence of mental health issues is significantly lower beyond minimum limits of neighborhood vegetation cover (depression >20% cover, anxiety >30% cover, stress >20% cover). Our findings demonstrate quantifiable associations of mental health with the characteristics of nearby nature that people actually experience

HIV Testing and Conspiracy Beliefs Regarding the Origins of HIV among African Americans

Abstract Conspiracy beliefs regarding the origins of HIV are common among African Americans, and have been associated with engaging in HIV risk behaviors but also with earlier diagnosis among HIV patients. The objective of the present study was to test the association of HIV serostatus testing with conspiracy beliefs. A total of 1430 African Americans from low-income neighborhoods with high rates of drug use were surveyed in 1997-1999 in face-to-face interviews. Two 4-point items assessed if participants agreed that AIDS was started by an experiment that went wrong and AIDS was created to kill blacks and poor folks. A binary variable indicated if the respondent agreed with the statements, on average. 22.5% of the sample endorsed conspiracy beliefs, 4.0% of whom reported not having had an HIV test, compared to 7.7% of those who did not endorse conspiracy beliefs. In multivariable logistic regression modeling, never having had an HIV test was significantly associated with conspiracy beliefs (adjusted odds ratio [AOR]=0.43, 95% confidence interval [CI]=1.3-4.3), having a high school education (AOR=0.55, CI=0.35-0.84), having depression (AOR=1.61, CI=1.02-2.52), female gender (AOR=0.54, CI=0.34-0.86), younger age, and a history of injection drug use (AOR=0.36, CI=0.23-0.56), but not sex risk behaviors (multiple partners, irregular condom use). The finding that individuals who have conspiracy beliefs are more likely to have been tested for HIV may partially explain why HIV-positive individuals who endorse conspiracy beliefs are more likely to obtain an earlier diagnosis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78123/1/apc.2009.0061.pd

Why do Particle Clouds Generate Electric Charges?

Grains in desert sandstorms spontaneously generate strong electrical charges; likewise volcanic dust plumes produce spectacular lightning displays. Charged particle clouds also cause devastating explosions in food, drug and coal processing industries. Despite the wide-ranging importance of granular charging in both nature and industry, even the simplest aspects of its causes remain elusive, because it is difficult to understand how inert grains in contact with little more than other inert grains can generate the large charges observed. Here, we present a simple yet predictive explanation for the charging of granular materials in collisional flows. We argue from very basic considerations that charge transfer can be expected in collisions of identical dielectric grains in the presence of an electric field, and we confirm the model's predictions using discrete-element simulations and a tabletop granular experiment