Search results for "numerical [methods]"
showing 10 items of 500 documents
Relativistic MHD simulations of extragalactic jets
2005
We have performed a comprehensive parameter study of the morphology and dynamics of axisymmetric, magnetized, relativistic jets by means of numerical simulations. The simulations have been performed with an upgraded version of the GENESIS code which is based on a second-order accurate finite volume method involving an approximate Riemann solver suitable for relativistic ideal magnetohydrodynamic flows, and a method of lines. Starting from pure hydrodynamic models we consider the effect of a magnetic field of increasing strength (up to β ≡ |b|2/2p ≈ 3.3 times the equipartition value) and different topology (purely toroidal or poloidal). We computed several series of models investigating the …
Field and Numerical Tests of the Two-Ponding Depth Procedure for Analysis of Single-Ring Pressure Infiltrometer Data
2013
Abstract The two-ponding depth (TPD) analysis procedure of single-ring infiltrometer data can yield invalid results, i.e., negative values of the field-saturated soil hydraulic conductivity or the matric flux potential, denoting failure of the two-level run. The objective of this study was to test the performance of the TPD procedure in analyzing the single-ring infiltrometer data of different types of soils. A field investigation carried out in western Sicily, Italy, yielded higher failure rates (40%) in two clay loam soils than in a sandy loam soil (25%). A similar result, i.e., fine-textured soils yielding higher failure rates than the coarse-textured one, was obtained using numerically …
Future capabilities of CME polarimetric 3D reconstructions with the METIS instrument: A numerical test
2015
D.H.M. would like to thank STFC and the Leverhulme Trust for their financial support. P.P. would like to thank STFC and the Leverhulme Trust. The computational work for this paper was carried out on the joint STFC and SFC (SRIF) funded cluster at the University of St Andrews (Scotland, UK). Context. Understanding the 3D structure of coronal mass ejections (CMEs) is crucial for understanding the nature and origin of solar eruptions. However, owing to the optical thinness of the solar corona we can only observe the line of sight integrated emission. As a consequence the resulting projection effects hide the true 3D structure of CMEs. To derive information on the 3D structure of CMEs from whit…
Geo-economic variations in epidemiology, patterns of care, and outcomes in patients with acute respiratory distress syndrome: insights from the LUNG …
2017
Background Little information is available about the geo-economic variations in demographics, management, and outcomes of patients with acute respiratory distress syndrome (ARDS). We aimed to characterise the effect of these geo-economic variations in patients enrolled in the Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE). Methods LUNG SAFE was done during 4 consecutive weeks in winter, 2014, in a convenience sample of 459 intensive-care units in 50 countries across six continents. Inclusion criteria were admission to a participating intensive-care unit (including transfers) within the enrolment window and receipt of invasive or non…
Cyberbullying and traditional bullying among Nordic adolescents and their impact on life satisfaction.
2019
Aims: The aim of this study was to investigate the prevalence of cybervictimization in the six Nordic countries and to assess its overlap with traditional bullying. A further aim was to examine potential associations between life satisfaction, on the one hand, and traditional bullying and cyberbullying on the other. Methods: Analyses were based on data from the 2013⁄2014 Health Behaviour in School-aged Children study. It included 32,210 boys and girls, aged 11, 13, and 15, living in the six Nordic countries. Results: The prevalence of cyberbullying by both pictures and by messages was around 2% in all the Nordic countries except Greenland. There it was considerably higher. The prevalence o…
Meta-analysis of 74,046 individuals identifies 11 new susceptibility loci for Alzheimer's disease
2013
Eleven susceptibility loci for late-onset Alzheimer's disease (LOAD) were identified by previous studies; however, a large portion of the genetic risk for this disease remains unexplained. We conducted a large, two-stage meta-analysis of genome-wide association studies (GWAS) in individuals of European ancestry. In stage 1, we used genotyped and imputed data (7,055,881 SNPs) to perform meta-analysis on 4 previously published GWAS data sets consisting of 17,008 Alzheimer's disease cases and 37,154 controls. In stage 2, 11,632 SNPs were genotyped and tested for association in an independent set of 8,572 Alzheimer's disease cases and 11,312 controls. In addition to the APOE locu…
Patterns of transmitted HIV drug resistance in Europe vary by risk group
2014
BACKGROUND: In Europe, a continuous programme (SPREAD) has been in place for ten years to study transmission of drug resistant HIV. We analysed time trends of transmitted drug resistance mutations (TDRM) in relation to the risk behaviour reported. METHODS: HIV-1 patients newly diagnosed in 27 countries from 2002 through 2007 were included. Inclusion was representative for risk group and geographical distribution in the participating countries in Europe. Trends over time were calculated by logistic regression. RESULTS: From the 4317 patients included, the majority was men-having-sex-with-men -MSM (2084, 48%), followed by heterosexuals (1501, 35%) and injection drug users (IDU) (355, 8%). MSM…
Survival of European patients diagnosed with lymphoid neoplasms in 2000-2002: results of the HAEMACARE project.
2011
The European Cancer Registry-based project on hematologic malignancies (HAEMACARE), set up to improve the availability and standardization of data on hematologic malignancies in Europe, used the European Cancer Registry-based project on survival and care of cancer patients (EUROCARE-4) database to produce a new grouping of hematologic neoplasma(defined by the International Classification of Diseases for Oncology, Third Edition and the 2001/2008 World Health Organization classifications) for epidemiological and public health purposes. We analyzed survival for lymphoid neoplasms in Europe by disease group, comparing survival between different European regions by age and sex. Design and Method…
Safety of primary anastomosis following emergency left sided colorectal resection: an international, multi-centre prospective audit
2018
Introduction: Some evidence suggests that primary anastomosis following left sided colorectal resection in the emergency setting may be safe in selected patients, and confer favourable outcomes to permanent enterostomy. The aim of this study was to compare the major postoperative complication rate in patients undergoing end stoma vs primary anastomosis following emergency left sided colorectal resection. Methods: A pre-planned analysis of the European Society of Coloproctology 2017 audit. Adult patients (> 16 years) who underwent emergency (unplanned, within 24 h of hospital admission) left sided colonic or rectal resection were included. The primary endpoint was the 30-day major complic…
Is VIRTU4L larger than VIR7UAL? Automatic processing of number quantity and lexical representations in leet words.
2015
Recent research has shown that leet words (i.e., words in which some of the letters are replaced by visually similar digits; e.g., VIRTU4L) can be processed as their base words without much cost. However, it remains unclear whether the digits inserted in leet words are simply processed as letters or whether they are simultaneously processed as numbers (i.e., in terms of access to their quantity representation). To address this question, we conducted two experiments that examined the size congruity effect (i.e., when comparisons of the physical size of numbers are affected by their numerical magnitudes) in a physical-size judgment task. Participants were presented with pairs of leet words th…