The kinematic-wave theory of particle settling in tube centrifuges has become a subject of scientific discussion. Specifically, the common assumption was made that the flow in a rotating tube of ...large length/diameter ratio can be treated in one-dimensional approximation. The respective results have been found in agreement with measurements. However, an analysis of the two-dimensional settling process performed in the limit of vanishing particle concentration led to some results that are not in accordance with the one-dimensional flow approximation, irrespective of the length/diameter ratio. It is the aim of the present investigation to gain a better understanding of the process. According to the analysis presented here, quasi-one-dimensional kinematic waves are embedded in a two-dimensional bulk flow that is governed by the continuity equation for the mixture plus the boundary conditions at the walls of the tube. The results based on simplification assumptions are compared with those of the one-dimensional flow approximation. Limiting cases, based on an elaborate analysis of three distinct settling models, are investigated analytically, and the plausibility of some of the respective results is evaluated also in the context of the one-dimensional approximation. Experimental observations, reported in the time span 2001 through 2008, are compared with analytical results obtained and presented. Further experimental work beyond this time span is also analyzed.
•Novel numerical vortex-based scheme for incompressible Euler flow.•Vorticity-Bernoulli-pressure formulation.•Results compare well with unsteady analytical solutions.•Second-order accurate in space ...and accurate in long-time simulations.
A novel numerical formulation and time-integration method for the incompressible Euler flow equations is presented using the vorticity–Bernoulli-pressure system. Lagrangian advection of vorticity-carrying particles is adopted from classical vortex methods that are known to give accurate results for vortex-dominated flows and allow larger time steps than explicit Eulerian schemes. Solving only one scalar Poisson equation per time step instead of a vector-valued equation in vortex methods makes the new scheme theoretically more efficient on large computational grids. The equation of motion in rotation form is integrated in time under certain approximation assumptions and solved explicitly for the flow velocity. The velocity is eliminated as an unknown in the continuity equation, which is efficiently solved for the Bernoulli pressure using the predicted vorticity field obtained by Lagrangian advection. The Bernoulli pressure is efficiently obtained from the Poisson equation in finite volume formulation. An estimated velocity field is calculated from the equation of motion. To effectively counterbalance the discretization errors made by the prediction, in a corrector step the kinematic relation between vorticity and estimated velocity is reformulated and solved in a Lagrangian framework as well. The velocity field is corrected at the end of the time step. Two-dimensional cases on Cartesian grids are considered. Numerical results for three flow cases demonstrate the locally smooth and accurate behavior and the second-order spatial accuracy of the solution. The new scheme produces significantly less artificial vortex distortion than the classical vortex method. The favorable properties of the solutions with respect to accuracy and long-time stability of the overall kinetic energy and enstrophy are also emphasized.
Yak belly hair was proposed as a cheap substitute for human hair for the development of hair dyes, as its chemical composition closely resembles human hair in Raman spectroscopy. The absence of ...melanin in yak belly hair also leads to a strong reduction of fluorescence in Raman measurements, which is advantageous for the investigation of the effectivity of hair dyes. To assess the suitability for replacing human hair, we analyzed similarities and differences of both hair types with a variety of methods: Raman spectroscopy, to obtain molecular information; small-angle X-ray scattering to determine the nanostructure, such as intermediate filament distance, distance of lipid layers and nanoporosity; optical and scanning electron microscopy of surfaces and cross sections to determine the porosity at the microstructural level; and density measurements and tensile tests to determine the macroscopic structure, macroporosity and mechanical properties. Both types of hair are similar on a molecular scale, but differ on other length scales: yak belly hair has a smaller intermediate filament distance on the nanoscale. Most striking is a higher porosity of yak belly hair on all hierarchical levels, and a lower Young's modulus on the macroscale. In addition to the higher porosity, yak belly hair has fewer overlapping scales of keratin, which further eases the uptake of coloring. This makes, on the other hand, a comparison of coloring processes difficult, and limits the usefulness of yak belly hair as a substitute for human hair.
Context. In recent years, our understanding of solar-like oscillations from main sequence to red giant stars has improved dramatically thanks to pristine data collected from space telescopes. One of ...the remaining open questions focuses on the observational identification of solar-like oscillations in pre-main sequence stars. Aims. We aim to develop an improved method to search for solar-like oscillations in pre-main sequence stars and apply it to data collected by the Kepler K2 mission. Methods. Our software APOLLO includes a novel way to detect low signal-to-noise ratio solar-like oscillations in the presence of a high background level. Results. By calibrating our method using known solar-like oscillators from the main Kepler mission, we apply it to T Tauri stars observed by Kepler K2 and identify several candidate pre-main sequence solar-like oscillators. Conclusions. We find that our method is robust even when applied to time-series of observational lengths as short as those obtained with the TESS satellite in one sector. We identify EPIC 205375290 as a possible candidate for solar-like oscillations in a pre-main sequence star with νmax ≃ 242 μHz. We also derive its fundamental parameters to be Teff = 3670 ± 180 K, log g = 3.85 ± 0.3, v sin i = 8 ± 1 km s−1, and about solar metallicity from a high-resolution spectrum obtained from the Keck archive.
Breast cancer is genetically heterogeneous, and recent studies have underlined a prominent contribution of epigenetics to the development of this disease. To uncover new synthetic lethalities with ...known breast cancer oncogenes, we screened an epigenome-focused short hairpin RNA library on a panel of engineered breast epithelial cell lines. Here we report a selective interaction between the NOTCH1 signaling pathway and the SUMOylation cascade. Knockdown of the E2-conjugating enzyme UBC9 (UBE2I) as well as inhibition of the E1-activating complex SAE1/UBA2 using ginkgolic acid impairs the growth of NOTCH1-activated breast epithelial cells. We show that upon inhibition of SUMOylation NOTCH1-activated cells proceed slower through the cell cycle and ultimately enter apoptosis. Mechanistically, activation of NOTCH1 signaling depletes the pool of unconjugated small ubiquitin-like modifier 1 (SUMO1) and SUMO2/3 leading to increased sensitivity to perturbation of the SUMOylation cascade. Depletion of unconjugated SUMO correlates with sensitivity to inhibition of SUMOylation also in patient-derived breast cancer cell lines with constitutive NOTCH pathway activation. Our investigation suggests that SUMOylation cascade inhibitors should be further explored as targeted treatment for NOTCH-driven breast cancer.
Context.
F-type stars are characterised by several physical processes such as different pulsation mechanisms, rotation, convection, diffusion, and magnetic fields. The rapidly rotating
δ
Scuti star
β
...Cas can be considered as a benchmark star to study the interaction of several of these effects.
Aims.
We investigate the pulsational and magnetic field properties of
β
Cas. We also determine the star’s apparent fundamental parameters and chemical abundances.
Methods.
Based on photometric time series obtained from three different space missions (BRITE-Constellation, SMEI, and TESS), we conduct a frequency analysis and investigate the stability of the pulsation amplitudes over four years of observations. We investigate the presence of a magnetic field and its properties using spectropolarimetric observations taken with the Narval instrument by applying the least-squares deconvolution and Zeeman-Doppler imaging techniques.
Results.
The star
β
Cas shows only three independent
p
-mode frequencies down to the few ppm-level; its highest amplitude frequency is suggested to be an
n
= 3,
ℓ
= 2,
m
= 0 mode. Its magnetic field structure is quite complex and almost certainly of a dynamo origin. The atmosphere of
β
Cas is slightly deficient in iron peak elements and slightly overabundant in C, O, and heavier elements.
Conclusions.
Atypically for
δ
Scuti stars, we can only detect three pulsation modes down to exceptionally low noise levels for
β
Cas. The star is also one of very few
δ
Scuti pulsators known to date to show a measurable magnetic field and the first
δ
Scuti star with a dynamo magnetic field. These characteristics make
β
Cas an interesting target for future studies of dynamo processes in the thin convective envelopes of F-type stars, the transition region between fossil and dynamo fields, and the interaction between pulsations and magnetic field.
In this study, in operandi SAXS experiments were conducted on samples of human hair with a varying degree of strain (2% within the elastic region and 10% beyond). Four different features in the SAXS ...patterns were evaluated: The intermediate filament distance perpendicular to and the distance from the meridional arc in the load direction, as well as the distances of the lipid bilayer peak in and perpendicular to the load direction. From the literature, one concludes that polar lipids in the cuticle are the origin of the lipid peak in the SAXS pattern, and this study shows that the observed strain in the lipids is much lower than in the intermediate filaments. We support these findings with SEM micrographs, which show that the scales in the cuticle deform much less than the cortex. The observed deformation of the intermediate filaments is very high, about 70% of the macrostrain, and the ratio of the transverse strain to the longitudinal strain at the nanoscale gives a Poisson ratio of ν
= 0.44, which is typical for soft matter. This work also finds that by varying the time period between two strain cycles, the typical strain recovery time is about 1000 min, i.e., one day. After this period, the structure is nearly identical to the initial structure, which suggests an interpretation that this is the typical time for the self-healing of hair after mechanical treatment.
Antibody‐mediated rejection (AMR) frequently causes refractory graft dysfunction. This randomized controlled trial was designed to evaluate whether immunoadsorption (IA) is effective in the treatment ...of severe C4d‐positive AMR. Ten out of 756 kidney allograft recipients were included. Patients were randomly assigned to IA with protein A (N = 5) or no such treatment (N = 5) with the option of IA rescue after 3 weeks. Enrolled recipients were subjected to tacrolimus conversion and, if indicated, ‘anti‐cellular’ treatment. All IA‐treated patients responded to treatment. One death unrelated to IA occurred after successful reversal of rejection. Four control subjects remained dialysis‐dependent. With the exception of one patient who developed graft necrosis, non‐responders were subjected to rescue IA, however, without success. Because of a high graft loss rate in the control group the study was terminated after a first interim analysis. Even though limited by small patient numbers, this trial suggests efficiency of IA in reversing severe AMR.
This randomized controlled trial, which was prematurely terminated because of a high graft loss rate in a control group subjected to tacrolimus conversion and (if indicated) anti‐cellular treatment only, suggests efficiency of immunoadsorption with protein A in reversing severe C4d‐positive antibody‐mediated rejection.
Objective: Treatment with statins reduces the risk of ischemic stroke among patients at increased risk for vascular disease. Recent experimental data suggest neuroprotective properties of statins in ...acute cerebral ischemia. We investigated whether a premedication with statins is associated with a better outcome in patients with acute ischemic cerebrovascular events.
Methods: Within a cross-sectional study, nested in a cohort we identified 1691 patients with a recent ischemic stroke or transient ischemic attack. Clinical severity of the vascular event was evaluated by the modified Rankin Scale (mRS) after 1 week. By means of multivariate logistic regression modeling, we determined the influence of prior statin use on stroke severity with adjustment for potential confounding factors.
Results: Severe stroke, defined as a modified Rankin Scale of 5 or 6 (
n=231; 14%), was less frequent in patients receiving statin treatment before the event (6% vs. 14%, OR=0.37; 95% CI 0.19 to 0.74;
p=0.004). This association remained significant after adjustment for confounding factors. We found a significant interaction between the presence of diabetes and the effect of pretreatment with statins on stroke outcome. Of the patients with diabetes, none of those on statin treatment but 16% of those without a statin had a bad outcome. After exclusion of the group of diabetic patients with prior statin medication, the protective effect was reduced and not statistically significant anymore.
Conclusions: Pretreatment with statins seems to be associated with reduced clinical severity in patients with acute ischemic cerebrovascular events, particularly in patients with diabetes.
Vasopressors for shock Müllner, M; Urbanek, B; Havel, C ...
Cochrane database of systematic reviews,
2004
3
Journal Article
Peer reviewed
Besides reversing the underlying cause, the first line treatment for the symptoms of shock is usually the administration of intravenous fluids. If this method is not successful, vasopressors such as ...dopamine, dobutamine, adrenaline, noradrenaline and vasopressin are recommended. It is unclear if there is a vasopressor of choice, either for the treatment of particular forms of shock or for the treatment of shock in general.
To assess the efficacy of vasopressors for circulatory shock in critically ill patients. Our main aim was to assess whether particular vasopressors reduce overall mortality. We also intended to identify whether the choice of vasopressor influences outcomes such as length-of-stay in the intensive care unit and health-related quality of life.
We searched MEDLINE, the Cochrane Central Register of Controlled Trials, EMBASE, PASCAL BioMed, CINAHL, BIOSIS, and PsychINFO:all from inception to November 2003; for randomized controlled trials. We also asked experts in the field and searched meta-registries for ongoing trials.
We included randomized controlled trials comparing various vasopressors, vasopressors with placebo or vasopressors with intravenous fluids for the treatment of any kind of circulatory failure (shock). Mortality was the main outcome.
Two reviewers abstracted data independently. Disagreement between two reviewers was discussed and resolved with a third reviewer. We used random effects models for combining quantitative data.
We identified eight randomized controlled trials. Reporting of methodological details was for many items not satisfactory: only two studies reported allocation concealment, and two that the outcome assessor was blind to the intervention. Two studies compared norepinephrine plus dobutamine with epinephrine alone in patients with septic shock (52 patients, relative risk of death 0.98, 95% confidence interval 0.57 to 1.67). Three studies compared norepinephrine with dopamine in patients with septic shock (62 patients, relative risk 0.88, 0.57 to 1.36). Two studies compared vasopressin with placebo in patients with septic shock (58 patients, relative risk 1.04, 0.06 to 19.33). One study compared terlipressin with norepinephrine in patients with refractory hypotension after general anaesthesia but there were no deaths (20 patients).
The current available evidence is not suited to inform clinical practice. We were unable to determine whether a particular vasopressor is superior to other agents in the treatment of states of shock.
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