885 research outputs found
Intramode and Fermi relaxation in CO2, their influence on multiple-pass, short-pulse energy extraction
Analytical, experimental and numerical results concerning the influence of intramode and Fermi relaxation on multiple-pass, nanosecond-pulse energy extraction are presented. Multiple-pass energy extraction experiments show satisfactory agreement with the analytical and numerical calculations which predict a significant increase in extracted energy. In three passes, an amount of 9.7 J/l was extracted at an efficiency of 4.3%, These values are taken with respect to the volume of the beam inside the amplifier. In a single pass only 3.5 J/l was extracted
Impact of dynamic computed tomographic angiography on endograft sizing for endovascular aneurysm repair.
Contains fulltext :
80349.pdf (publisher's version ) (Open Access)PURPOSE: To quantify dynamic changes in aortoiliac dimensions using dynamic electrocardiographically (ECG)-gated computed tomographic angiography (CTA) and to investigate any potential impact on preoperative endograft sizing in relation to observer variability. METHODS: Dynamic ECG-gated CTA was performed in 18 patients with abdominal aortic aneurysms. Postprocessing resulted in 11 datasets per patient: 1 static CTA and 10 dynamic CTA series. Vessel diameter, length, and angulation were measured for all phases of the cardiac cycle. The differences between diastolic and systolic aneurysm dimensions were analyzed for significance using paired t tests. To assess intraobserver variability, 20 randomly selected datasets were analyzed twice. Intraobserver repeatability coefficients (RC) were calculated using Bland-Altman analysis. RESULTS: Mean aortic diameter at the proximal neck was 21.4+/-3.0 mm at diastole and 23.2+/-2.9 mm at systole, a mean increase of 1.8+/-0.4 mm (8.5%, p<0.01). The RC for the aortic diameter at the level of the proximal aneurysm neck was 1.9 mm (8.9%). At the distal sealing zones, the mean increase in diameter was 1.7+/-0.3 mm (14.1%, p<0.01) for the right and 1.8+/-0.5 mm (14.2%, p<0.01) for the left common iliac artery (CIA). At both distal sealing zones, the mean increase in CIA diameter exceeded the RC (10.0% for the right CIA and 12.6% for the left CIA). CONCLUSION: The observed changes in aneurysm dimension during the cardiac cycle are small and in the range of intraobserver variability, so dynamic changes in proximal aneurysm neck diameter and aneurysm length likely have little impact on preoperative endograft selection. However, changes in diameter at the distal sealing zones may be relevant to sizing, so distal oversizing of up to 20% should be considered to prevent distal type I endoleak
Optical properties of tungsten thin films perforated with a bidimensional array of subwavelength holes
We present a theorical investigation of the optical transmission of a
dielectric grating carved in a tungsten layer. For appropriate wavelengths
tungsten shows indeed a dielectric behaviour. Our numerical simulations leads
to theoretical results similar to those found with metallic systems studied in
earlier works. The interpretation of our results rests on the idea that the
transmission is correlated with the resonant response of eigenmodes coupled to
evanescent diffraction orders.Comment: 4 pages, 3 figure
On the invariance under area preserving diffeomorphisms of noncommutative Yang-Mills theory in two dimensions
We present an investigation on the invariance properties of noncommutative
Yang-Mills theory in two dimensions under area preserving diffeomorphisms.
Stimulated by recent remarks by Ambjorn, Dubin and Makeenko who found a
breaking of such an invariance, we confirm both on a fairly general ground and
by means of perturbative analytical and numerical calculations that indeed
invariance under area preserving diffeomorphisms is lost. However a remnant
survives, namely invariance under linear unimodular tranformations.Comment: LaTeX JHEP style, 16 pages, 2 figure
Two-dimensional non-commutative Yang-Mills theory: coherent effects in open Wilson line correlators
A perturbative calculation of the correlator of three parallel open Wilson
lines is performed for the U(N) theory in two non-commutative space-time
dimensions. In the large-N planar limit, the perturbative series is fully
resummed and asymptotically leads to an exponential increase of the correlator
with the lengths of the lines, in spite of an interference effect between lines
with the same orientation. This result generalizes a similar increase occurring
in the two-line correlator and is likely to persist when more lines are
considered provided they share the same direction.Comment: 22 pages, 1 figure, typeset in JHEP styl
Flavonoids Influence Monocytic GTPase Activity and Are Protective in Experimental Allergic Encephalitis
In the chronic disabling disease multiple sclerosis (MS), migration of monocytes across the blood-brain barrier is a crucial step in the formation of new lesions in the central nervous system (CNS). Infiltrating monocyte-derived macrophages secrete inflammatory mediators such as oxygen radicals, which contribute to axonal demyelination and damage, resulting in neurological deficits. Flavonoids are compounds occurring naturally in food, which scavenge oxygen radicals and have antiinflammatory properties. To investigate whether they might suppress clinical symptoms in MS, we treated rats sensitized for acute and chronic experimental allergic encephalomyelitis, an experimental model of MS, with flavonoids. We demonstrated that the flavonoid luteolin substantially suppressed clinical symptoms and prevented relapse when administered either before or after disease onset. Luteolin treatment resulted in reduced inflammation and axonal damage in the CNS by preventing monocyte migration across the brain endothelium. Luteolin influenced migration by modulating the activity of Rho GTPases, signal transducers involved in transendothelial migration. Oral administration of luteolin also significantly reduced clinical symptoms
Is optimising gout treatment the key to closing the mortality gap in gout patients?
Pathophysiology and treatment of rheumatic disease
- …