Energy Dissipation and Trapping of Particles Moving on a Rough Surface

We report an experimental, numerical and theoretical study of the motion of a ball on a rough inclined surface. The control parameters are $D$, the diameter of the ball, $\theta$, the inclination angle of the rough surface and $E_{ki}$, the initial kinetic energy. When the angle of inclination is larger than some critical value, $\theta>\theta_{T}$, the ball moves at a constant average velocity which is independent of the initial conditions. For an angle $\theta < \theta_{T}$, the balls are trapped after moving a certain distance. The dependence of the travelled distances on $E_{ki}$, $D$ and $\theta$. is analysed. The existence of two kinds of mechanisms of dissipation is thus brought to light. We find that for high initial velocities the friction force is constant. As the velocity decreases below a certain threshold the friction becomes viscous.Comment: 8 pages RevTeX, 12 Postscript figure

Instability of dilute granular flow on rough slope

We study numerically the stability of granular flow on a rough slope in collisional flow regime in the two-dimension. We examine the density dependence of the flowing behavior in low density region, and demonstrate that the particle collisions stabilize the flow above a certain density in the parameter region where a single particle shows an accelerated behavior. Within this parameter regime, however, the uniform flow is only metastable and is shown to be unstable against clustering when the particle density is not high enough.Comment: 4 pages, 6 figures, submitted to J. Phys. Soc. Jpn.; Fig. 2 replaced; references added; comments added; misprints correcte

Prediction of final infarct volume from native CT perfusion and treatment parameters using deep learning

CT Perfusion (CTP) imaging has gained importance in the diagnosis of acute stroke. Conventional perfusion analysis performs a deconvolution of the measurements and thresholds the perfusion parameters to determine the tissue status. We pursue a data-driven and deconvolution-free approach, where a deep neural network learns to predict the final infarct volume directly from the native CTP images and metadata such as the time parameters and treatment. This would allow clinicians to simulate various treatments and gain insight into predicted tissue status over time. We demonstrate on a multicenter dataset that our approach is able to predict the final infarct and effectively uses the metadata. An ablation study shows that using the native CTP measurements instead of the deconvolved measurements improves the prediction.Comment: Accepted for publication in Medical Image Analysi

Metformin and sitAgliptin in patients with impAired glucose tolerance and a recent TIA or minor ischemic Stroke (MAAS): study protocol for a randomized controlled trial

Background: Impaired glucose tolerance is present in one third of patients with a TIA or ischemic stroke and is associated with a two-fold risk of recurrent stroke. Metformin improves glucose tolerance, but often leads to side effects. The aim of this study is to explore the feasibility, safety, and effects on glucose metabolism of metformin and sitagliptin in patients with TIA or minor ischemic stroke and impaired glucose tolerance. We will also assess whether a slow increase in metformin dose and better support and information on this treatment will reduce the incidence of side effects in these patients. Methods/Design: The Metformin and sitAgliptin in patients with impAired glucose tolerance and a recent TIA or minor ischemic Stroke trial (MAAS trial) is a phase II, multicenter, randomized, controlled, open-label trial with blinded outcome assessment. Non-diabetic patients (n = 100) with a recent (<6 months) TIA, amaurosis fugax or minor ischemic stroke (modified Rankin scale ≤ 3) and impaired glucose tolerance, defined as 2-hour post-load glucose levels between 7.8 and 11.0 mmol/L after repeated standard oral glucose tolerance test, will be included. Patients with renal or liver impairment, heart failure, chronic hypoxic lung disease stage III-IV, history of lactate acidosis or diabetic ketoacidosis, pregnancy or breastfeeding, pancreatitis and use of digoxin will be excluded. The patients will be randomly assigned in a 1:1:2 ratio to metformin, sitagliptin or "no treatment." Patients allocated to metformin will start with 500 mg twice daily, which will be slowly increased during a 6-week period to a twice daily dose of 1000 mg. Patients allocated to sitagliptin will be treated with a daily fixed dose of 100 mg. The study has been registered as NTR 3196 in The Netherlands Trial Register. Primary outcomes include percentage still on treatment, percentage of (serious) adverse events, and the baseline adjusted difference in 2-hour post-load glucose levels at 6 months. Discussion: This study will give more information about the feasibility and safety of metformin and sitagliptin as well as the effect on 2-hour post-load glucose levels at 6 months in patients with TIA or ischemic stroke and impaired glucose tolerance

Photochemical routes to silicon epitaxy

The photochemistry of Si2H6 adsorbed on a hydrogen terminated silicon surface and the subsequentreactions of the photolysis products were investigated using high resolution electron energy lossspectroscopy and by measuring time-of-flight distributions with a mass spectrometer. The crackingpattern of the products ejected directly into the gas phase without colliding with either the surfaceor other molecules indicates that the primary photolysis channels yield mostly fragments thatcontain one silicon atom. It is likely that silicon is added to the surface by insertion of SiH2 radicalsinto Si–H bonds at the surface but there is little evidence for reactions that remove excess hydrogenfrom the surface at 110

Verbetert paracetamol het herstel na een beroerte?

An increase in body temperature in the first days following stroke is related to poor functional outcome. High-dose paracetamol (acetaminophen) reduces the body temperature by 0.3°C and can prevent fever. Paracetamol treatment is simple, cheap and has few side effects. In the first "Paracetamol (Acetaminophen) in Stroke" (PAIS) study, there was a beneficial effect of high-dose paracetamol on functional outcome in patients with stroke and a body temperature of 37.0°C or above. Because this result was found in a subgroup analysis, a new study is needed to confirm this finding. Recently the randomised PAIS 2 study was initiated. This study aims to assess the effect of high-dose paracetamol on functional outcome in patients with acute stoke and a body temperature of 37.0°C or above.Een stijging van de lichaamstemperatuur in de eerste dagen na een beroerte is geassocieerd met een slechte prognose. Hoge dosis paracetamol verlaagt de lichaamstemperatuur gemiddeld met 0,3°C en kan koorts voorkómen. Behandeling met paracetamol is eenvoudig, zeer goedkoop en heeft weinig bijwerkingen. In het eerste ‘Paracetamol (Acetaminophen) in Stroke’(PAIS)-onderzoek verbeterde vroege behandeling met een hoge dosis paracetamol de functionele uitkomst van patiënten met een beroerte en een lichaamstemperatuur van 37,0°C of hoger. Dit effect werd echter gevonden in een subgroepanalyse en dient daarom nader te worden onderzocht. Recentelijk is het gerandomiseerde onderzoek PAIS 2 gestart. Hierin wordt het effect bestudeerd van behandeling met een hoge dosis paracetamol op functioneel herstel bij patiënten met een lichaamstemperatuur van 37,0°C of hoger in de acute fase van een beroerte

Value of thrombus CT Characteristics in Patients with Acute Ischemic Stroke

BACKGROUND AND PURPOSE: Thrombus CT characteristics might be useful for patient selection for intra-arterial treatment. Our objective was to study the association of thrombus CT characteristics with outcome and treatment effect in patients with acute ischemic stroke. MATERIALS AND METHODS: We included 199 patients for whom thin-section NCCT and CTA within 30 minutes from each other were available in the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute ischemic stroke in the Netherlands (MR CLEAN) study. We assessed the following thrombus characteristics: location, distance from ICA terminus to thrombus, length, volume, absolute and relative density

Mesoscopic motion of atomic ions in magnetic fields

We introduce a semiclassical model for moving highly excited atomic ions in a magnetic field which allows us to describe the mixing of the Landau orbitals of the center of mass in terms of the electronic excitation and magnetic field. The extent of quantum energy flow in the ion is investigated and a crossover from localization to delocalization with increasing center of mass energy is detected. It turns out that our model of the moving ion in a magnetic field is closely connected to models for transport in disordered finite-size wires.Comment: 4 pages, 2 figures, subm. to Phys.Rev.A, Rap.Co