250 research outputs found
Modeling shallow water flows on general terrains
No full textA formulation of the two-dimensional shallow water equations adapted to general and complex terrains
is proposed. Its derivation starts from the observation that the typical approach of depth integrating the
Navier–Stokes equations along the direction of gravity forces is not exact in the general case of a tilted
curved bottom. We claim that an integration path that better adapts to the shallow water hypotheses
follows the “cross-flow” surface, i.e., a surface that is normal to the velocity field at any point of the do-
main. Because of the implicitness of this definition, we approximate this “cross-flow” path by performing
depth integration along a local direction normal to the bottom surface, and propose a rigorous deriva-
tion of this approximation and its numerical solution as an essential step for the future development of
the full “cross-flow” integration procedure. We start by defining a local coordinate system, anchored on
the bottom surface to derive a covariant form of the Navier–Stokes equations. Depth integration along
the local normals yields a covariant version of the shallow water equations, which is characterized by
flux functions and source terms that vary in space because of the surface metric coefficients and related
derivatives. The proposed model is numerically discretized with a first order FORCE-type Godunov Finite
Volume scheme that allows straight forward implementation of spatially variable fluxes. We investigate
the validity of our SW model and the effects of the geometrical characteristics of the bottom surface
by means of three synthetic test cases that exhibit non negligible slopes and surface curvatures. The re-
sults show the importance of taking into consideration bottom geometry even for relatively mild and
slowly varying curvatures. By comparison with the numerical solution of vertically integrated models, we
observe differences of almost 20%, in particular for the peak values and the shape of the hydrographs
calculated at given sections of the fluid domai
Established and Emerging Cardiovascular Magnetic Resonance Imaging Techniques in the Evaluation of Subclinical Cardiovascular Disease
No full textIntroduction: Cardiovascular disease (CVD) remains the number one cause of mortality in the world for both men and women, thus improving its diagnosis and treatment is a priority. Rheumatoid Arthritis (RA) is a common auto-immune disease associated with high rates of CVD. Cardiovascular magnetic resonance (CMR) offers a multi-parametric, quantitative approach to the assessment of the heart and cardiovascular system with a host of techniques allowing assessment of anatomy, ventricular function, myocardial composition, myocardial perfusion, vascular performance and myocardial metabolism during a single scan. Its quantitative nature and lack of ionising radiation lend themselves ideally to the longitudinal study of subclinical CVD.
Aims: To assess 1) whether blood longitudinal relaxation (T1) can be used to estimate blood haematocrit value to allow calculation of extracellular myocardial volume fraction (ECV), 2) whether CMR feature tracking (CMR-FT) is a feasible means of assessing aortic stiffness, 3) whether global longitudinal strain (GLS) is reduced in patients with prior MI with preserved left ventricular ejection fraction versus healthy controls, 4) whether aortic stiffness is present at all time points in the disease course of RA and 5) whether subclinical CV abnormalities in newly diagnosed RA improve with treatment and if the anti-tumour necrosis α Inhibitor Etanercept offers additional benefit over standard treatment.
Methods: Patients were recruited between and February 2011 and February 2017. All patients underwent a comprehensive, multi-parametric CMR study including cine and late Gadolinium enhancement imaging at either 1.5 or 3.0T.
Results: 1) estimation of blood haematocrit from blood T1 value provides accurate estimation of ‘synthetic’ ECV, 2) CMR-FT assessment of aortic stiffness is feasible and provides reproducible values for descending and ascending aortic strain values, 3) GLS is reduced in prior MI patients versus healthy controls (-17.3 ± 3.7% versus -19.3 ± 1.9% respectively, p=0.012). A GLS cut-off value of 18% correctly identifies prior MI with a sensitivity of 60% and specificity of 72.5%, 4) Aortic stiffness is evident in at risk RA individuals, newly diagnosed RA as well as established RA and 5) Aortic distensibility and left ventricular mass improve significantly in newly diagnosed RA patients following treatment. Etanercept appears to offer additional benefit over standard treatment evidenced by numerical improvements in aortic distensibility
0007 Simulation based medical education as a student selected component for medical students
No full textRecommended from our members
Indians Off Track: Cody's Wild West and the Melrose Park Train Wreck of 1904
No full text“We were rounding a curve,” recalled Luther Standing Bear, Sioux author, interpreter for the Indian members of Buffalo Bill Cody’s Wild West, and casualty of the Melrose Park train wreck of 1904, ”when suddenly I saw a train behind us, coming at lightning speed. Then came a terrific crash. There was no time even to cry out. When I opened my eyes again, the seats were piled on top of us and the steam and smoke from the engine were pouring in on us in great clouds. My legs were pinned down, and I was perfectly helpless . . . . Blood was everywhere.”
Buffalo Bill Cody’s Wild West, a depiction of the American frontier experience, traveled and performed throughout the United States and Europe. By 1904, it was a well-established and well-known entertainment attraction in its twenty-first year of operation.
Train wrecks were among the greatest dangers faced by the members of traveling shows around the turn of the nineteenth century. One of the most dramatic but unpublicized accidents of Cody’s Wild West happened near Melrose Park, Illinois, on 7 April 1904. According to Luther Standing Bear, the Indians were riding in the last car of the train, which, in effect, segregated them from the other passengers, when another train traveling behind them at ”lightening speed” plowed into the back of the Indians’ car. Standing Bear was one of the more seriously injured, sustaining three bruised and two broken ribs, cuts above both eyes, a severe gash on the back of his head, dislocation of both hips, and a broken left arm, left leg, collar bone, and nose
simulation helps in identification of latent errors and improves knowledge: Multi centre, multispecialty study project
No full textIn situ simulation as a tool for patient safety: a systematic review identifying how it is used and its effectiveness
No full textBACKGROUND: In situ simulation is an emerging technique involving interdisciplinary teams working through simulated scenarios which replicate events encountered in healthcare institutions, particularly those which are either low frequency or associated with high risk to patients. Since it takes place in the clinical environment, it is ideally suited to improving patient safety outcomes. OBJECTIVE: To identify and appraise all studies assessing contribution of in situ simulation to patient safety, identify gaps in knowledge and areas for future research, as well as suggesting strategies for maximising its impact on patient safety within an institution. STUDY SELECTION: Three electronic databases (MEDLINE, PubMed and EMBASE) as well as the Cochrane Library were searched for articles relating to patient safety outcomes in in situ simulation. In addition a subject expert was approached to suggest any additional articles not identified by electronic searches. A total of 1795 abstracts were identified and screened, 35 full articles assessed for eligibility for inclusion and a total of 18 full articles included in the review after unsuitable articles were excluded. CONCLUSIONS: In situ simulation can improve real-life patient safety outcomes, with 2 studies demonstrating improved morbidity and mortality outcomes following initiation of in situ simulation. There is good evidence to suggest that its implementation leads to improved clinical skills, teamwork and observed behaviours. Additionally, it is ideally suited to detecting latent safety errors (errors identified within a scenario which, if they had occurred in real life, could have led to a degree of harm occurring to a patient)
Two Outline Models of Science: AMS And HAMS
No full textTwo abstract and computational models of the long-term process of science are proposed: AMS and HAMS. An outline specification of each model is given and the relationship between them explained. AMS takes an Olympian (\"artificial world\") view of science and its processes. HAMS is simpler and relatively more abstract and comprises only a small set of core processes. A first implementation of HAMS is described. How AMS and HAMS might be validated and used in experimental investigations is considered including problems that might arise. Further work is proposed. A brief coda concerns a related model of science formulated from an idealist rather than a materialist perspective.Computational Models of Science, Individual-Based Modelling, Scientific Method, Belief Systems, Belief Verification, Idealism
81 Assessment of a novel, web-based, open-access training resource for junior trainees in echocardiography
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