128 research outputs found
Numerical Simulations of Pinhole and Single Mode Fibre Spatial Filters for Optical Interferometers
We use a numerical simulation to investigate the effectiveness of pinhole
spatial filters at optical/IR interferometers and to compare them with
single-mode optical fibre spatial filters and interferometers without spatial
filters. We show that fringe visibility measurements in interferometers
containing spatial filters are much less affected by changing seeing conditions
than equivalent measurements without spatial filters. This reduces visibility
calibration uncertainties, and hence can reduce the need for frequent
observations of separate astronomical sources for calibration of visibility
measurements. We also show that spatial filters can increase the
signal-to-noise ratios of visibility measurements and that pinhole filters give
signal-to-noise ratios within 17% of values obtained with single-mode fibres
for aperture diameters up to 3r_0. Given the simplicity of the use of pinhole
filters we suggest that it represents a competitive, if not optimal, technique
for spatial filtering in many current and next generation interferometers.Comment: 7 pages, 7 postscript figures. Accepted by MNRA
Effects of flutter and PEP mask physiotherapy on symptoms and lung function in children with cystic fibrosis
Recently, the flutter was introduced as a new device to improve sputum
expectoration. Preliminary data suggested a significant improvement in
expectoration and lung function during flutter treatment in patients with
cystic fibrosis (CF). The aim of the present study was to compare the
effects of the flutter and the positive expiratory pressure (PEP) mask on
symptoms and lung function in children with CF. In a crossover randomized
study 22 patients with CF (mean age 12 yrs, range 7-17 yrs) performed
physiotherapy using either the flutter or the PEP mask twice a day during
two treatment periods of 2 weeks, separated by a one week wash-out period,
in a random sequence. Lung function parameters (peak expiratory flow,
forced vital capacity (FVC), forced expiratory volume in one second,
maximal midexpiratory flow, maximal expiratory flow at 25% of FVC,
thoracic gas volume, total lung capacity, residual volume/total lung
capacity, airway resistance and specific airway conductance) and changes
in transcutaneous oxygen haemoglobin saturation were assessed before and
after the first supervised session and at the end of each treatment
period. Throughout the study peak flow was measured and symptoms were
scored daily. No significant changes in any lung function parameter
occurred after a single session or after 2 weeks of physiotherapy with
either method. There was no difference in acceptability and subjective
efficacy. In conclusion, any superiority of the flutter over the positive
expiratory pressure mask technique for expectoration could not be
confirmed during 2 weeks of daily treatment in children with cystic
fibrosis. Both methods are well accepted by children and do not change
lung function. Long-term comparison of both methods, including
expectoration measurements, seems to be required for further evaluation of
the potential success of physiotherapy in cystic fibrosis
Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results
The chromosphere is a thin layer of the solar atmosphere that bridges the
relatively cool photosphere and the intensely heated transition region and
corona. Compressible and incompressible waves propagating through the
chromosphere can supply significant amounts of energy to the interface region
and corona. In recent years an abundance of high-resolution observations from
state-of-the-art facilities have provided new and exciting ways of
disentangling the characteristics of oscillatory phenomena propagating through
the dynamic chromosphere. Coupled with rapid advancements in
magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly
investigate the role waves play in supplying energy to sustain chromospheric
and coronal heating. Here, we review the recent progress made in
characterising, categorising and interpreting oscillations manifesting in the
solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review
Исследование кинетики накопления коллоидного гептасульфида рения
SummaryInflammatory cytokines are well-recognized mediators of atherosclerosis. Depending on the pathological context, type I interferons (IFNs; IFNα and IFNβ) exert either pro- or anti-inflammatory immune functions, but their exact role in atherogenesis has not been clarified. Here, we demonstrate that IFNβ enhances macrophage-endothelial cell adhesion and promotes leukocyte attraction to atherosclerosis-prone sites in mice in a chemokine-dependent manner. Moreover, IFNβ treatment accelerates lesion formation in two different mouse models of atherosclerosis and increases macrophage accumulation in the plaques. Concomitantly, absence of endogenous type I IFN signaling in myeloid cells inhibits lesion development, protects against lesional accumulation of macrophages, and prevents necrotic core formation. Finally, we show that type I IFN signaling is upregulated in ruptured human atherosclerotic plaques. Hereby, we identify type I IFNs as proatherosclerotic cytokines that may serve as additional targets for prevention or treatment
Hemostatic efficacy of pathogen-inactivated vs untreated platelets: a randomized controlled trial
Stemcel biology/Regenerative medicine (incl. bloodtransfusion
- …