Investigation on numerical schemes in the simulation of barotropic cavitating flows

A numerical methodology for the simulation of cavitating flows is considered. A homogeneous-flow cavitation model, accounting for thermal effects and active nuclei concentration, is considered, which leads to a barotropic state law. The continuity and momentum equations for compressible inviscid flows are discretized through a finite-volume approach, applicable to unstructured grids. The numerical fluxes are computed by shockcapturing schemes and adhoc preconditioning is used to avoid accuracy problems in the low-Mach regime. Second-order accuracy in space is obtained through MUSCL reconstruction. Time advancing is carried out by an implicit linearized scheme. Two different numerical fluxes are investigated here, viz. the Roe and the Rusanov schemes. For the Rusanov flux two different time linearizations are proposed; in the first one the upwind part of the flux function is frozen in time, while in the second one its time variation is taken into account, although in an approximated manner. The different schemes and the different linearizations are appraised for the quasi 1D-flow in a nozzle through comparison against exact solutions and for the flow around a hydrofoil mounted in a wind tunnel through comparison against experimental data. Non-cavitating and cavitating conditions are simulated. It is shown that, for cavitating conditions, the Rusanov scheme together with the more complete time linearization allows time steps much larger than for the Roe scheme to be used. Finally, the results obtained with this scheme are in good agreement with the exact solutions or the experimental data for all the considered test cases.http://deepblue.lib.umich.edu/bitstream/2027.42/84242/1/CAV2009-final42.pd

Vitamin D and ω-3 Supplementations in Mediterranean Diet During the 1st Year of Overt Type 1 Diabetes: A Cohort Study

Vitamin D and omega 3 fatty acid (\u3c9-3) co-supplementation potentially improves type 1 diabetes (T1D) by attenuating autoimmunity and counteracting inflammation. This cohort study, preliminary to a randomized control trial (RCT), is aimed at evaluating, in a series of T1D children assuming Mediterranean diet and an intake of cholecalciferol of 1000U/day from T1D onset, if \u3c9-3 co-supplementation preserves the residual endogen insulin secretion (REIS). Therefore, the cohort of 22 \u201cnew onsets\u201d of 2017 received \u3c9-3 (eicosapentenoic acid (EPA) plus docosahexaenoic acid (DHA), 60 mg/kg/day), and were compared retrospectively vs. the 37 \u201cprevious onsets\u201d without \u3c9-3 supplementation. Glicosilated hemoglobin (HbA1c%), the daily insulin demand (IU/Kg/day) and IDAA1c, a composite index (calculated as IU/Kg/day 7 4 + HbA1c%), as surrogates of REIS, were evaluated at recruitment (T0) and 12 months later (T12). In the \u3c9-3 supplemented group, dietary intakes were evaluated at T0 and T12. As an outcome, a decreased insulin demand (p < 0.01), particularly as pre-meal boluses (p < 0.01), and IDAA1c (p < 0.05), were found in the \u3c9-3 supplemented group, while HbA1c% was not significantly different. Diet analysis in the \u3c9-3 supplemented group, at T12 vs. T0, highlighted that the intake of arachidonic acid (AA) decreased (p < 0.01). At T0, the AA intake was inversely correlated with HbA1c% (p < 0.05; r;. 0.411). In conclusion, the results suggest that vitamin D plus \u3c9-3 co-supplementation as well as AA reduction in the Mediterranean diet display benefits for T1D children at onset and deserve further investigation

Hunter disease eClinic: interactive, computer-assisted, problem-based approach to independent learning about a rare genetic disease

<p>Abstract</p> <p>Background</p> <p>Computer-based teaching (CBT) is a well-known educational device, but it has never been applied systematically to the teaching of a complex, rare, genetic disease, such as Hunter disease (MPS II).</p> <p>Aim</p> <p>To develop interactive teaching software functioning as a virtual clinic for the management of MPS II.</p> <p>Implementation and Results</p> <p>The <it>Hunter disease eClinic</it>, a self-training, user-friendly educational software program, available at the Lysosomal Storage Research Group (<url>http://www.lysosomalstorageresearch.ca</url>), was developed using the Adobe Flash multimedia platform. It was designed to function both to provide a realistic, interactive virtual clinic and instantaneous access to supporting literature on Hunter disease. The <it>Hunter disease eClinic </it>consists of an <it>eBook </it>and an <it>eClinic</it>. The <it>eClinic </it>is the interactive virtual clinic component of the software. Within an environment resembling a real clinic, the trainee is instructed to perform a medical history, to examine the patient, and to order appropriate investigation. The program provides clinical data derived from the management of actual patients with Hunter disease. The <it>eBook </it>provides instantaneous, electronic access to a vast collection of reference information to provide detailed background clinical and basic science, including relevant biochemistry, physiology, and genetics. In the <it>eClinic</it>, the trainee is presented with quizzes designed to provide immediate feedback on both trainee effectiveness and efficiency. User feedback on the merits of the program was collected at several seminars and formal clinical rounds at several medical centres, primarily in Canada. In addition, online usage statistics were documented for a 2-year period. Feedback was consistently positive and confirmed the practical benefit of the program. The online English-language version is accessed daily by users from all over the world; a Japanese translation of the program is also available.</p> <p>Conclusions</p> <p>The Hunter disease <it>eClinic </it>employs a CBT model providing the trainee with realistic clinical problems, coupled with comprehensive basic and clinical reference information by instantaneous access to an electronic textbook, the <it>eBook</it>. The program was rated highly by attendees at national and international presentations. It provides a potential model for use as an educational approach to other rare genetic diseases.</p

Tissue Doppler imaging of carotid plaque wall motion: a pilot study

BACKGROUND: Studies suggest the physical and mechanical properties of vessel walls and plaque may be of clinical value in the diagnosis and treatment of cardiovascular atherosclerotic disease. The purpose of this pilot study was to investigate the potential clinical application of ultrasound Tissue Doppler Imaging (TDI) of Arterial Wall Motion (AWM) and to quantify simple wall motion indices in normal and diseased carotid arteries. METHODS: 224 normal and diseased carotid arteries (0–100% stenoses) were imaged in 126 patients (age 25–88 years, mean 68 ± 11). Longitudinal sections of the carotid bifurcation were imaged using a Philips HDI5000 scanner and L12-5 probe under optimized TDI settings. Temporal and spatial AWMs were analyzed to evaluate the vessel wall displacements and spatial gradients at peak systole averaged over 5 cardiac cycles. RESULTS: AWM data were successfully extracted in 91% of cases. Within the carotid bifurcation/plaque region, the maximum wall dilation at peak systole ranged from -100 to 750 microns, mean 335 ± 138 microns. Maximum wall dilation spatial gradients ranged 0–0.49, mean 0.14 ± 0.08. The AWM parameters showed a wide variation and had poor correlation with stenoses severity. Case studies illustrated a variety of pertinent qualitative and quantitative wall motion features related to the biophysics of arterial disease. CONCLUSION: Our clinical experience, using a challenging but realistic imaging protocol, suggests the use of simple quantitative AWM measures may have limitations due to high variability. Despite this, pertinent features of AWM in normal and diseased arteries demonstrate the potential clinical benefit of the biomechanical information provided by TDI