7,232 research outputs found
Coherent imaging of extended objects
When used with coherent light, optical imaging systems, even
diffraction-limited, are inherently unable to reproduce both the amplitude and
the phase of a two-dimensional field distribution because their impulse
response function varies slowly from point to point (a property known as
non-isoplanatism). For sufficiently small objects, this usually results in a
phase distortion and has no impact on the measured intensity. Here, we show
that the intensity distribution can also be dramatically distorted when objects
of large extension or of special shapes are imaged. We illustrate the problem
using two simple examples: the pinhole camera and the aberration-free thin
lens. The effects predicted by our theorical analysis are also confirmed by
experimental observations.Comment: 10 pages, 9 figures, submitted to Optics Communication
GASTOF: Ultra-fast ToF forward detector for exclusive processes at the LHC
GASTOF (Gas Time-of-Flight) detector is a Cherenkov detector proposed for
very precise (10--20 ps) arrival time measurements of forward protons at some
420 m from the central detectors of CMS and ATLAS. Such an excellent time
resolution will allow by z-by-timing technique for precise measurement of the
z-coordinate of the event vertex in exclusive production at the LHC, when two
colliding protons are scattered at very small angles. In the paper we present
first GASTOF prototype, simulations of its performance as well as first tests
using a cosmic muon telescope.Comment: 6 pages, 3 figures, presented at the conference ''Physics at LHC'',
Krakow, June 200
Infrared Exponents and the Running Coupling of Landau gauge QCD and their Relation to Confinement
The infrared behaviour of the gluon and ghost propagators in Landau gauge QCD
is reviewed. The Kugo-Ojima confinement criterion and the Gribov-Zwanziger
horizon condition result from quite general properties of the ghost
Dyson-Schwinger equation. The numerical solutions for the gluon and ghost
propagators obtained from a truncated set of Dyson-Schwinger equations provide
an explicit example for the anticipated infrared behaviour. The results are in
good agreement with corresponding lattice data obtained recently. The resulting
running coupling approaches a fix point in the infrared, . Two different fits for the scale dependence of the running coupling
are given and discussed.Comment: 3 pages, 3 figures; talk given by R.A. at the conference Quark
Nuclear Physics 200
Emerging role of angiogenesis in adaptive and maladaptive right ventricular remodeling in pulmonary hypertension
Right ventricular (RV) function is the primary prognostic factor for both morbidity and mortality in pulmonary hypertension (PH). RV hypertrophy is initially an adaptive physiological response to increased overload; however, with persistent and/or progressive afterload increase, this response frequently transitions to more pathological maladaptive remodeling. The mechanisms and disease processes underlying this transition are mostly unknown. Angiogenesis has recently emerged as a major modifier of RV adaptation in the setting of pressure overload. A novel paradigm has emerged that suggests that angiogenesis and angiogenic signaling are required for RV adaptation to afterload increases and that impaired and/or insufficient angiogenesis is a major driver of RV decompensation. Here, we summarize our current understanding of the concepts of maladaptive and adaptive RV remodeling, discuss the current literature on angiogenesis in the adapted and failing RV, and identify potential therapeutic approaches targeting angiogenesis in RV failure
Added value of bleach sedimentation microscopy for diagnosis of pulmonary tuberculosis: cost-effectiveness study
IUATLD Conference, Paris, 200
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