Risk factors for death in hospitalized dysentery patients in Rwanda.

To evaluate the management of severe dysentery cases in in-patient facilities during an epidemic of Shigella dysenteriae type 1 (Sd1), and to identify the factors associated with the risk of death, we conducted a prospective cohort study in 10 Rwandese hospitals between September and December 1994. Data were obtained from 849 cases admitted to hospitals with diarrhoea and visible blood in stools. The proportion of patients with persistent bloody diarrhoea was 51.0% at treatment day 3 and 27.9% at treatment day 5. At discharge, 79.9% had improved or were cured. The case fatality ratio was 13.2%, higher for patients treated with nalidixic acid than for those treated with ciprofloxacin (12.2% vs. 2.2%, RR = 5.80, 95% CI = 0.83-40.72). In a logistic regression model three risk factors were significantly associated with an increased risk of death during hospitalization: severe dehydration on admission (adjusted OR = 2.79, 95% CI = 1.46-5.33), age over 50 (adjusted OR vs. 5-49 age group = 3.22, 95% CI = 1.70-6.11) and prescription of nalidixic acid (adjusted OR vs. ciprofloxacin = 8.66, 95% CI = 1.08-69.67). Those results were consistent with reported high levels of resistance of Sd1 to the commonest antibiotics, including nalidixic acid. Patients belonging to groups with a higher risk of dying should be given special medical attention and supportive care. In areas of high resistance to nalidixic acid, severe cases of dysentery should be treated with fluoroquinolones in order to reduce the mortality associated with these epidemics

Stochastic semi-continuous simulation for extreme flood estimation in catchments with combined rainfall–snowmelt flood regimes

Simulation methods for extreme flood estimation represent an important complement to statistical flood frequency analysis because a spectrum of catchment conditions potentially leading to extreme flows can be assessed. In this paper, stochastic, semi-continuous simulation is used to estimate extreme floods in three catchments located in Norway, all of which are characterised by flood regimes in which snowmelt often has a significant role. The simulations are based on SCHADEX, which couples a precipitation probabilistic model with a hydrological simulation such that an exhaustive set of catchment conditions and responses is simulated. The precipitation probabilistic model is conditioned by regional weather patterns, and a bottom–up classification procedure was used to define a set of weather patterns producing extreme precipitation in Norway. SCHADEX estimates for the 1000-year (Q1000) discharge are compared with those of several standard methods, including event-based and long-term simulations which use a single extreme precipitation sequence as input to a hydrological model, statistical flood frequency analysis based on the annual maximum series, and the GRADEX method. The comparison suggests that the combination of a precipitation probabilistic model with a long-term simulation of catchment conditions, including snowmelt, produces estimates for given return periods which are more in line with those based on statistical flood frequency analysis, as compared with the standard simulation methods, in two of the catchments. In the third case, the SCHADEX method gives higher estimates than statistical flood frequency analysis and further suggests that the seasonality of the most likely Q1000 events differs from that of the annual maximum flows. The semi-continuous stochastic simulation method highlights the importance of considering the joint probability of extreme precipitation, snowmelt rates and catchment saturation states when assigning return periods to floods estimated by precipitation-runoff methods. The SCHADEX methodology, as applied here, is dependent on observed discharge data for calibration of a hydrological model, and further study to extend its application to ungauged catchments would significantly enhance its versatility

Introducing a rainfall compound distribution model based on weather patterns sub-sampling

This paper presents a probabilistic model for daily rainfall, using sub-sampling based on meteorological circulation. We classified eight typical but contrasted synoptic situations (weather patterns) for France and surrounding areas, using a "bottom-up" approach, i.e. from the shape of the rain field to the synoptic situations described by geopotential fields. These weather patterns (WP) provide a discriminating variable that is consistent with French climatology, and allows seasonal rainfall records to be split into more homogeneous sub-samples, in term of meteorological genesis. <br><br> First results show how the combination of seasonal and WP sub-sampling strongly influences the identification of the asymptotic behaviour of rainfall probabilistic models. Furthermore, with this level of stratification, an asymptotic exponential behaviour of each sub-sample appears as a reasonable hypothesis. This first part is illustrated with two daily rainfall records from SE of France. <br><br> The distribution of the multi-exponential weather patterns (MEWP) is then defined as the composition, for a given season, of all WP sub-sample marginal distributions, weighted by the relative frequency of occurrence of each WP. This model is finally compared to Exponential and Generalized Pareto distributions, showing good features in terms of robustness and accuracy. These final statistical results are computed from a wide dataset of 478 rainfall chronicles spread on the southern half of France. All these data cover the 1953–2005 period

Early Ontogenetic Diet in Gray Wolves, Canis lupus, of Coastal British Columbia

Within populations, different age classes often consume dissimilar resources, and provisioning of juveniles by adults is one mechanism by which this can occur. Although the diet of Gray Wolves (Canis lupus) has been studied extensively, the diet of pups is largely unknown. We examined faeces deposited by altricial pups and adult providers during the first two months following birth at two den sites over two years on the central coast of British Columbia, Canada. Pups and adult wolves consumed similar species, and Black-tailed Deer (Odocoileus hemionus) constituted most of the diet for both age groups. Pup and adult diet, however, diverged. Specifically, adult deer occurred significantly less frequently in the diet of pups than in the diet of adult wolves, which suggests that adults selectively provisioned pups. We speculate that this may relate to adaptive strategies of adult wolves to provide their offspring with food of optimal nutritional value or reduced parasitic burden, and/or logistic factors associated with provisioning such as prey transportability and availability

Early Ontogenetic Diet in Gray Wolves, Canis lupus, of Coastal British Columbia

Within populations, different age classes often consume dissimilar resources, and provisioning of juveniles by adults is one mechanism by which this can occur. Although the diet of Gray Wolves (Canis lupus) has been studied extensively, the diet of pups is largely unknown. We examined faeces deposited by altricial pups and adult providers during the first two months following birth at two den sites over two years on the central coast of British Columbia, Canada. Pups and adult wolves consumed similar species, and Black-tailed Deer (Odocoileus hemionus) constituted most of the diet for both age groups. Pup and adult diet, however, diverged. Specifically, adult deer occurred significantly less frequently in the diet of pups than in the diet of adult wolves, which suggests that adults selectively provisioned pups. We speculate that this may relate to adaptive strategies of adult wolves to provide their offspring with food of optimal nutritional value or reduced parasitic burden, and/or logistic factors associated with provisioning such as prey transportability and availability

3D Model Retrieval with Spherical Harmonics and Moments

We consider 3D object retrieval in which a polygonal mesh serves as a query and similar objects are retrieved from a collection of 3D objects. Algorithms proceed first by a normalization step in which models are transformed into canonical coordinates. Second, feature vectors are extracted and compared with those derived from normalized models in the search space. In the feature vector space nearest neighbors are computed and ranked. Retrieved objects are displayed for inspection, selection, and processing. Our feature vectors are based on rays cast from the center of mass of the object. For each ray the object extent in the ray direction yields a sample of a function on the sphere. We compared two kinds of representations of this function, namely spherical harmonics and moments. Our empirical comparison using precision-recall diagrams for retrieval results in a data base of 3D models showed that the method using spherical harmonics performed better

A New Scenario on the Metal-Insulator Transition in VO2

The metal-insulator transition in VO2 was investigated using the three-band Hubbard model, in which the degeneracy of the 3d orbitals, the on-site Coulomb and exchange interactions, and the effects of lattice distortion were considered. A new scenario on the phase transition is proposed, where the increase in energy level separation among the t_2g orbitals caused by the lattice distortion triggers an abrupt change in the electronic configuration in doubly occupied sites from an S=1 Hund's coupling state to a spin S=0 state with much larger energy, and this strongly suppresses the charge fluctuation. Although the material is expected to be a Mott-Hubbard insulator in the insulating phase, the metal-to-insulator transition is not caused by an increase in relative strength of the Coulomb interaction against the electron hopping as in the usual Mott transition, but by the level splitting among the t_2g orbitals against the on-site exchange interaction. The metal-insulator transition in Ti2O3 can also be explained by the same scenario. Such a large change in the 3d orbital occupation at the phase transition can be detected by linear dichroic V 2p x-ray absorption measurements.Comment: 5 pages, 5 figures, to be published in J. Phys. Soc. Jpn. Vol. 72 No. 1