297 research outputs found
The spatial organisation of time-averaged streamwise velocity and its correlation with the surface topography of water-worked gravel beds
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The experimental and numerical approach of two-phase flows by wall jets on rough beds in open channel flow
YesThis paper presents the results of investigations
carried out to study the effect of horizontal wall jets on a fixed
rough bed in an open channel. The study used both numerical
and experimental approaches. The numerical and experimental
studies are compared for validation. The main objective of this
study is to understand the effect of wall jets on a horizontal
fixed rough bed in an open channel.
The experimental study investigated the effect of wall jets on
a fixed horizontal bed, with a known roughness in an open
channel flume. A sid-looking Acoustic Doppler Velocimetry
(ADV) was used to measure the velocity profile of the flow at
different flow zones. The wave monitor was used to measure the
free surface during the experiments.
Computational fluid dynamics CFD simulations were
conducted in a rectangular channel to compare with the
laboratory tests using the volume of fluid VOF multiphase
method and K- ࢿ model. The two phase (water and air) was
used in this study. Computer simulations for the model were
used to predict the fluid horizontal velocity (u) revealing the
characteristics of the wall jet over different flow zones
(developing, fully developed and recovering zones).
The results showed that the velocity profiles distribution in
the stream wise direction in the channel were reasonable. The
reverse velocity was close to the wall jet and the maximum
reverse velocity was observed near the water surface. Also the
results showed that the depression was close to the wall jet.
The agreement between the results obtained from the
numerical and the experimental data were reasonable
Determining hydraulic resistance in gravel-bed rivers from the dynamics of their water surfaces
Critical role of general practitioners in preventing readmission following emergency department alcohol screening and brief intervention management of alcohol-related problems
Introduction/Objectives: Alcohol screening and brief intervention (ASBI) strategies are useful in general practice (GP) but their effectiveness in the emergency department (ED) is unclear. We evaluated the effect of ED-based ASBI on re-admissions. Methods: 453 ED subjects exceeding the threshold score on the three-item Alcohol Use Disorders Identification Test-Consumption (females 3+: males 4+) were randomized. We conducted telephone follow-up at 1 and 3 months and recorded hospital events 6 months pre- and post-enrolment. Results: Median weekly alcohol use was 20 standard drinks (interquartile range (IQR) 9-45) on enrolment. After 3 months, 247 (55%) were able to be re-interviewed. Median alcohol use was 10 drinks (IQR 4-26). Six months later, subjects receiving ED-ASBI without GP follow-up had significantly greater risk of re-admission compared with those having GP follow-up (OR 1.68, 95%CI 1.06-2.65; P =.028). Conclusions: ASBI reduces the likelihood of ED re-presentation only in subjects who have GP follow-up. The study has been registered as a clinical trial (Australian and New Zealand Clinical Trial Registry ACTRN12617001254381)
Critical role of general practitioners in preventing readmission following emergency department alcohol screening and brief intervention management of alcohol-related problems
Introduction/Objectives: Alcohol screening and brief intervention (ASBI) strategies are useful in general practice (GP) but their effectiveness in the emergency department (ED) is unclear. We evaluated the effect of ED-based ASBI on re-admissions. Methods: 453 ED subjects exceeding the threshold score on the three-item Alcohol Use Disorders Identification Test-Consumption (females 3+: males 4+) were randomized. We conducted telephone follow-up at 1 and 3 months and recorded hospital events 6 months pre- and post-enrolment. Results: Median weekly alcohol use was 20 standard drinks (interquartile range (IQR) 9-45) on enrolment. After 3 months, 247 (55%) were able to be re-interviewed. Median alcohol use was 10 drinks (IQR 4-26). Six months later, subjects receiving ED-ASBI without GP follow-up had significantly greater risk of re-admission compared with those having GP follow-up (OR 1.68, 95%CI 1.06-2.65; P =.028). Conclusions: ASBI reduces the likelihood of ED re-presentation only in subjects who have GP follow-up. The study has been registered as a clinical trial (Australian and New Zealand Clinical Trial Registry ACTRN12617001254381)
Knockout of ERK5 causes multiple defects in placental and embryonic development
BACKGROUD: ERK5 is a member of the mitogen activated protein kinase family activated by certain mitogenic or stressful stimuli in cells, but whose physiological role is largely unclear. RESULTS: To help determine the function of ERK5 we have used gene targeting to inactivate this gene in mice. Here we report that ERK5 knockout mice die at approximately E10.5. In situ hybridisation for ERK5, and its upstream activator MKK5, showed strong expression in the head and trunk of the embryo at this stage of development. Between E9.5 and E10.5, multiple developmental problems are seen in the ERK5-/- embryos, including an increase in apoptosis in the cephalic mesenchyme tissue, abnormalities in the hind gut, as well as problems in vascular remodelling, cardiac development and placental defects. CONCLUSION: Erk5 is essential for early embryonic development, and is required for normal development of the vascular system and cell survival
Towards understanding the clinical significance of QT peak prolongation: a novel marker of myocardial ischemia independently demonstrated in two prospective studies
Background: QT peak prolongation identified patients at risk of death or non-fatal MI. We tested the hypothesis that QT peak prolongation might be associated with significant myocardial ischaemia in two separate cohorts to see how widely applicable the concept was. Methods and Results: In the first study, 134 stroke survivors were prospectively recruited and had 12-lead ECGs and Nuclear myocardial perfusion scanning. QT peak was measured in lead I of a 12-lead ECG and heart rate corrected by Bazett’s formula (QTpc). QTpc prolongation to 360ms or more was 92% specific at diagnosing severe myocardial ischaemia. This hypothesis-generating study led us to perform a second prospective study in a different cohort of patients who were referred for dobutamine stress echocardiography. 13 of 102 patients had significant myocardial ischaemia. Significant myocardial ischaemia was associated with QT peak prolongation at rest (mean 354ms, 95% CI 341-367ms, compared with mean 332ms, 95% CI 327-337ms in those without significant ischaemia; p=0.002). QT peak prolongation to 360ms or more was 88% specific at diagnosing significant myocardial ischaemia in the stress echocardiography study. QT peak prolongation to 360ms or more was associated with over 4-fold increase odds ratio of significant myocardial ischaemia. The Mantel- Haenszel Common Odds Ratio Estimate=4.4, 95% CI=1.2-16.0, p=0.023. Conclusion: QT peak (QTpc) prolongation to 360ms or more should make us suspect the presence of significant myocardial ischaemia. Such patients merit further investigations for potentially treatable ischaemic heart disease to reduce their risk of subsequent death or non-fatal MI
Knots and Particles
Using methods of high performance computing, we have found indications that
knotlike structures appear as stable finite energy solitons in a realistic 3+1
dimensional model. We have explicitly simulated the unknot and trefoil
configurations, and our results suggest that all torus knots appear as
solitons. Our observations open new theoretical possibilities in scenarios
where stringlike structures appear, including physics of fundamental
interactions and early universe cosmology. In nematic liquid crystals and 3He
superfluids such knotted solitons might actually be observed.Comment: 9 pages, 4 color eps figures and one b/w because of size limit (color
version available from authors
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