4,021 research outputs found
Multireference Stochastic Coupled Cluster.
We describe a modification of the stochastic coupled cluster algorithm that allows the use of multiple reference determinants. By considering the secondary references as excitations of the primary reference and using them to change the acceptance criteria for selection and spawning, we obtain a simple form of stochastic multireference coupled cluster which preserves the appealing aspects of the single-reference approach. The method is able to successfully describe strongly correlated molecular systems using few references and low cluster truncation levels, showing promise as a tool to tackle strong correlation in more general systems. Moreover, it allows simple and comprehensive control of the included references and excitors thereof, and this flexibility can be taken advantage of to gain insight into some of the inner workings of established electronic structure methods
Material-independent crack arrest statistics: Application to indentation experiments
An extensive experimental study of indentation and crack arrest statistics is
presented for four different brittle materials (alumina, silicon carbide,
silicon nitride, glass). Evidence is given that the crack length statistics can
be described by a universal (i.e. material independent) distribution. The
latter directly derives from results obtained when modeling crack propagation
as a depinning phenomenon. Crack arrest (or effective toughness) statistics
appears to be fully characterized by two parameters, namely, an asymptotic
crack length (or macroscopic toughness) value and a power law size dependent
width. The experimental knowledge of the crack arrest statistics at one given
scale thus gives access to its knowledge at all scales
Age and petrogenesis of the Lundy granite: Paleocene intraplate peraluminous magmatism in the Bristol Channel, UK
This is the author accepted manuscript. The final version is available from Geological Society via the DOI in this record.The Lundy granite forms part of the Lundy Igneous Complex, which is the southernmost substantive expression of magmatism within both the British Cenozoic Igneous Province and the wider North Atlantic Igneous Province. Its Qz + Pl + Kfs + Bt ± Grt ± Tpz mineralogy and peraluminous character contrast with other British Cenozoic Igneous Province granites farther north but are similar to the granites of the adjacent Early Permian Cornubian Batholith. We present the results of mapping, petrographical and mineral chemical analysis, and the first U–Pb zircon ages for the granite (59.8 ± 0.4 – 58.4 ± 0.4 Ma) and cross-cutting basic dykes (57.2 ± 0.5 Ma), which confirm a Paleocene age for magmatism. Zircon inheritance is limited but two cores imply the presence of Early Palaeozoic igneous rocks in the unexposed basement of SW England. The anomalous southerly location of the Lundy Igneous Complex is a consequence of mantle melting arising from the superimposition of localized lithospheric extension, related to intraplate strike-slip tectonics, with the distal ancestral Icelandic plume. Granite generation primarily reflects crustal partial melting during the emplacement of mantle-derived melts. The change in geochemical character between the Lundy granite (peraluminous) and other British Cenozoic Igneous Province granites (metaluminous or subalkaline) indicates a fundamental crustal source control between contrasting peri-Gondwanan and Laurentian basement provinces.Financial assistance was received from University College Oxford, the Geologists’ Association, the Lundy Field Society and the Burdett-Coutts fund
Diagrammatic Coupled Cluster Monte Carlo.
We propose a modified coupled cluster Monte Carlo algorithm that stochastically samples connected terms within the truncated Baker-Campbell-Hausdorff expansion of the similarity-transformed Hamiltonian by construction of coupled cluster diagrams on the fly. Our new approach-diagCCMC-allows propagation to be performed using only the connected components of the similarity-transformed Hamiltonian, greatly reducing the memory cost associated with the stochastic solution of the coupled cluster equations. We show that for perfectly local, noninteracting systems diagCCMC is able to represent the coupled cluster wavefunction with a memory cost that scales linearly with system size. The favorable memory cost is observed with the only assumption of fixed stochastic granularity and is valid for arbitrary levels of coupled cluster theory. Significant reduction in memory cost is also shown to smoothly appear with dissociation of a finite chain of helium atoms. This approach is also shown not to break down in the presence of strong correlation through the example of a stretched nitrogen molecule. Our novel methodology moves the theoretical basis of coupled cluster Monte Carlo closer to deterministic approaches.Sims Fun
Genomic linkage map of the human blood fluke Schistosoma mansoni
The first genetic linkage map of Schistosoma mansoni reveals insights into higher female recombination, confirms ZW inheritance patterns and recombination hotspots
Prevention of large-vessel stenoses in atypical hemolytic uremic syndrome associated with complement dysregulation
Mosquito Abundance, Bed net Coverage and Other Factors Associated with Variations in Sporozoite Infectivity Rates in Four Villages of Rural Tanzania.
Entomological surveys are of great importance in decision-making processes regarding malaria control strategies because they help to identify associations between vector abundance both species-specific ecology and disease intervention factors associated with malaria transmission. Sporozoite infectivity rates, mosquito host blood meal source, bed net coverage and mosquito abundance were assessed in this study. A longitudinal survey was conducted in four villages in two regions of Tanzania. Malaria vectors were sampled using the CDC light trap and pyrethrum spray catch methods. In each village, ten paired houses were selected for mosquitoes sampling. Sampling was done in fortnight case and study was undertaken for six months in both Kilimanjaro (Northern Tanzania) and Dodoma (Central Tanzania) regions. A total of 6,883 mosquitoes were collected including: 5,628 (81.8%) Anopheles arabiensis, 1,100 (15.9%) Culex quinquefasciatus, 89 (1.4%) Anopheles funestus, and 66 (0.9%) Anopheles gambiae s.s. Of the total mosquitoes collected 3,861 were captured by CDC light trap and 3,022 by the pyrethrum spray catch method. The overall light trap: spray catch ratio was 1.3:1. Mosquito densities per room were 96.5 and 75.5 for light trap and pyrethrum spray catch respectively. Mosquito infectivity rates between villages that have high proportion of bed net owners and those without bed nets was significant (P < 0.001) and there was a significant difference in sporozoite rates between households with and without bed nets in these four villages (P < 0.001). Malaria remains a major problem in the study areas characterized as low transmission sites. Further studies are required to establish the annual entomological inoculation rates and to observe the annual parasitaemia dynamics in these communities. Outdoor mosquitoes collection should also be considered
Ostéonécroses Aseptiques vues en Rhumatologie à Abidjan entre 2001 et 2011: Caractéristiques Épidémiologiques et Diagnostiques de 31 Patients
Objectif :
Etudier les caractéristiques épidémiologiques et diagnostiques des ostéonécroses aseptiques chez une population noire d’Afrique sub-saharienne. Patients et méthodes : Etude rétrospective descriptive sur 11 ans (janvier 2001 à décembre 2011) portant sur les patients vus pour une ostéonécrose aseptique en rhumatologie à Abidjan en Côte d’Ivoire.
Résultats : Sur 3592 patients vus pour une affection rhumatologique, 31 (0,86%) avaient une ostéonécrose aseptique (incidence annuelle moyenne de 2,58 cas). L’âge moyen des patients, 10 hommes et 21 femmes, était de 40,2+/-13,4 ans (extrêmes : 19 - 75 ans). Le délai diagnostique moyen était de 9,4 mois +/- 9,1 (extrêmes : 1 - 36 mois). Les patients consultaient surtout pour une forte douleur à début progressif (77,4%), d’évolution chronique (87,1%), avec impotence fonctionnelle (87,1%). Les facteurs de risques de l’ostéonécrose aseptique étaient l’hémoglobinopathie (38,7%), l’alcoolisme (35,4%), le surpoids/obésité (29,0%), les dyslipidémies (25,8%), la corticothérapie (16,1%), le tabagisme (16,1%), l’infection à VIH (9,7%), les troubles de la statique et traumatismes (9,7%), l’hyperuricémie (9,7%), et la polyarthrite rhumatoïde (3,2%). Il s’agissait d’ostéonécrose aseptique de la tête fémorale (90,3%), du condyle fémoral (6,45%), et de la tête humérale (3,2%). L’ostéonécrose aseptique de la tête fémorale était surtout classée stade III (32,3%) et IV (38,7%) selon Arlet et Ficat. Conclusion : L’ostéonécrose aseptique n’est pas rare en milieu rhumatologique à Abidjan. La tête fémorale est la plus touchée et les facteurs de risque les plus fréquents sont l’hémoglobinopathie, l’alcoolisme, le surpoids/obésité, et les dyslipidémies.
Objective: To study the epidemiologic and diagnostic characteristics of aseptic osteonecrosis in a black population in sub-Saharan Africa. Patients and Methods: Retrospective, descriptive study over 11 years (January 2001 to December 2011) of patients seen for aseptic osteonecrosis in rheumatology in Abidjan, CĂ´te d'Ivoire. Results: Out of 3592 patients seen in rheumatological pratice, 31 (0.86%) had aseptic osteonecrosis (mean annual incidence of 2.58 cases). The mean age of the patients, 10 men and 21 women, was 40.16+/-13.39 years (extremes: 19 - 75 years). The mean diagnostic delay was 9.4+/- 9.1 months (extremes: 1 - 36 months). The patients consulted mainly for severe pain with progressive onset (77.4%), chronic evolution (87.1%), with functional impotence (87.1%). The risk factors of aseptic osteonecrosis were hemoglobinopathy (38.7%), alcoholism (35.4%), overweight/obesity (29.0%), dyslipidemia (25.8%), corticosteroid therapy (16.1%), smoking (16.1%), HIV infection (9.7%), static disorders and trauma (9.7%), hyperuricemia (9.7%), and rheumatoid arthritis (3.2%). These were aseptic osteonecrosis of the femoral head (90.3%), femoral condyle (6.45%), and humeral head (3.2%). aseptic osteonecrosis of the femoral head was mostly classified as stage III (32.3%) and IV (38.7%) according to Arlet and Ficat. Conclusion: Aseptic osteonecrosis is not uncommon in rheumatology settings in Abidjan. The femoral head is the most affected and the most frequent risk factors are hemoglobinopathy, alcoholism, overweight/obesity, and dyslipidemia
Ostéonécroses Aseptiques vues en Rhumatologie à Abidjan entre 2001 et 2011: Caractéristiques Épidémiologiques et Diagnostiques de 31 Patients
Objectif :
Etudier les caractéristiques épidémiologiques et diagnostiques des ostéonécroses aseptiques chez une population noire d’Afrique sub-saharienne. Patients et méthodes : Etude rétrospective descriptive sur 11 ans (janvier 2001 à décembre 2011) portant sur les patients vus pour une ostéonécrose aseptique en rhumatologie à Abidjan en Côte d’Ivoire.
Résultats : Sur 3592 patients vus pour une affection rhumatologique, 31 (0,86%) avaient une ostéonécrose aseptique (incidence annuelle moyenne de 2,58 cas). L’âge moyen des patients, 10 hommes et 21 femmes, était de 40,2+/-13,4 ans (extrêmes : 19 - 75 ans). Le délai diagnostique moyen était de 9,4 mois +/- 9,1 (extrêmes : 1 - 36 mois). Les patients consultaient surtout pour une forte douleur à début progressif (77,4%), d’évolution chronique (87,1%), avec impotence fonctionnelle (87,1%). Les facteurs de risques de l’ostéonécrose aseptique étaient l’hémoglobinopathie (38,7%), l’alcoolisme (35,4%), le surpoids/obésité (29,0%), les dyslipidémies (25,8%), la corticothérapie (16,1%), le tabagisme (16,1%), l’infection à VIH (9,7%), les troubles de la statique et traumatismes (9,7%), l’hyperuricémie (9,7%), et la polyarthrite rhumatoïde (3,2%). Il s’agissait d’ostéonécrose aseptique de la tête fémorale (90,3%), du condyle fémoral (6,45%), et de la tête humérale (3,2%). L’ostéonécrose aseptique de la tête fémorale était surtout classée stade III (32,3%) et IV (38,7%) selon Arlet et Ficat. Conclusion : L’ostéonécrose aseptique n’est pas rare en milieu rhumatologique à Abidjan. La tête fémorale est la plus touchée et les facteurs de risque les plus fréquents sont l’hémoglobinopathie, l’alcoolisme, le surpoids/obésité, et les dyslipidémies.
Objective: To study the epidemiologic and diagnostic characteristics of aseptic osteonecrosis in a black population in sub-Saharan Africa. Patients and Methods: Retrospective, descriptive study over 11 years (January 2001 to December 2011) of patients seen for aseptic osteonecrosis in rheumatology in Abidjan, CĂ´te d'Ivoire. Results: Out of 3592 patients seen in rheumatological pratice, 31 (0.86%) had aseptic osteonecrosis (mean annual incidence of 2.58 cases). The mean age of the patients, 10 men and 21 women, was 40.16+/-13.39 years (extremes: 19 - 75 years). The mean diagnostic delay was 9.4+/- 9.1 months (extremes: 1 - 36 months). The patients consulted mainly for severe pain with progressive onset (77.4%), chronic evolution (87.1%), with functional impotence (87.1%). The risk factors of aseptic osteonecrosis were hemoglobinopathy (38.7%), alcoholism (35.4%), overweight/obesity (29.0%), dyslipidemia (25.8%), corticosteroid therapy (16.1%), smoking (16.1%), HIV infection (9.7%), static disorders and trauma (9.7%), hyperuricemia (9.7%), and rheumatoid arthritis (3.2%). These were aseptic osteonecrosis of the femoral head (90.3%), femoral condyle (6.45%), and humeral head (3.2%). aseptic osteonecrosis of the femoral head was mostly classified as stage III (32.3%) and IV (38.7%) according to Arlet and Ficat. Conclusion: Aseptic osteonecrosis is not uncommon in rheumatology settings in Abidjan. The femoral head is the most affected and the most frequent risk factors are hemoglobinopathy, alcoholism, overweight/obesity, and dyslipidemia
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