386 research outputs found
Early results on the use of chitosan-N-acetylcysteine (Lacrimera®) in the management of dry eye disease of varied etiology
PurposeTo evaluate the effect of once daily administration of chitosan-N-acetylcysteine (Lacrimera®) in the management of dry eye disease (DED).MethodsEighteen patients (3 male, 15 female) aged 25–86 years (mean 61.1) and suffering from moderate to severe DED with superficial punctate keratitis (SPK) were retrospectively evaluated after a trial of Lacrimera® drops (1 drop in the morning for 5 days only). All the patients were using other artificial tears before the treatment. All lubricants were stopped, and Lacrimera® was started instead. Slit-lamp examination and images were taken before and at 1 and 3 weeks follow-up after the treatment. The subjective (Ocular Surface Disease Index, OSDI) and objective (Oxford Grading System, OGS) evaluation was recorded. A paired student’s t test was performed to analyse the data.ResultsAt baseline, the SPK grade was I to IV (OGS) and the OSDI ranged from 25 to 71.4. Fifteen patients showed a statistically significant (p < 0.0001) improvement in OGS and the OSDI at 3 weeks post-treatment. Three patients showed no improvement.ConclusionsA single-dose instillation of chitosan-N-acetylcysteine for five consecutive days improved signs and symptoms in patients affected from DED from a variety of causes, who were refractory to standard treatment with lubricants. Given its posology, the absence of side effects and the results obtained Lacrimera® should be taken into consideration as a viable option in patients with moderate to severe DED
Photoluminescence dispersion as a probe of structural inhomogeneity in silica
We report time-resolved photoluminescence spectra of point defects in
amorphous silicon dioxide (silica), in particular the decay kinetics of the
emission signals of extrinsic Oxygen Deficient Centres of the second type from
singlet and directly-excited triplet states are measured and used as a probe of
structural inhomogeneity. Luminescence activity in sapphire
(-AlO) is studied as well and used as a model system to compare
the optical properties of defects in silica with those of defects embedded in a
crystalline matrix. Only for defects in silica, we observe a variation of the
decay lifetimes with emission energy and a time dependence of the first moment
of the emission bands. These features are analyzed within a theoretical model
with explicit hypothesis about the effect introduced by the disorder of
vitreous systems. Separate estimations of the homogenous and inhomogeneous
contributions to the measured emission linewidth are obtained: it is found that
inhomogeneous effects strongly condition both the triplet and singlet
luminescence activities of oxygen deficient centres in silica, although the
degree of inhomogeneity of the triplet emission turns out to be lower than that
of the singlet emission. Inhomogeneous effects appear to be negligible in
sapphire
Performance of Optically Readout GEM-based TPC with a 55Fe source
Optical readout of large Time Projection Chambers (TPCs) with multiple Gas
Electron Multipliers (GEMs) amplification stages has shown to provide very
interesting performances for high energy particle tracking. Proposed
applications for low-energy and rare event studies, such as Dark Matter search,
ask for demanding performance in the keV energy range. The performance of such
a readout was studied in details as a function of the electric field
configuration and GEM gain by using a Fe source within a 7 litre
sensitive volume detector developed as a part of the R\&D for the CYGNUS
project. Results reported in this paper show that the low noise level of the
sensor allows to operate with a 2~keV threshold while keeping a rate of
fake-events lesser than 10 per year. In this configuration, a detection
efficiency well above 95\% along with an energy resolution () of 18\%
is obtained for the 5.9 keV photons, demonstrating the very promising
capabilities of this technique
A 1 m Gas Time Projection Chamber with Optical Readout for Directional Dark Matter Searches: the CYGNO Experiment
The aim of the CYGNO project is the construction and operation of a 1~m
gas TPC for directional dark matter searches and coherent neutrino scattering
measurements, as a prototype toward the 100-1000~m (0.15-1.5 tons) CYGNUS
network of underground experiments. In such a TPC, electrons produced by
dark-matter- or neutrino-induced nuclear recoils will drift toward and will be
multiplied by a three-layer GEM structure, and the light produced in the
avalanche processes will be readout by a sCMOS camera, providing a 2D image of
the event with a resolution of a few hundred micrometers. Photomultipliers will
also provide a simultaneous fast readout of the time profile of the light
production, giving information about the third coordinate and hence allowing a
3D reconstruction of the event, from which the direction of the nuclear recoil
and consequently the direction of the incoming particle can be inferred. Such a
detailed reconstruction of the event topology will also allow a pure and
efficient signal to background discrimination. These two features are the key
to reach and overcome the solar neutrino background that will ultimately limit
non-directional dark matter searches.Comment: 5 page, 7 figures, contribution to the Conference Records of 2018
IEEE NSS/MI
Fast algorithm for real-time rings reconstruction
The GAP project is dedicated to study the application of GPU in several contexts in which
real-time response is important to take decisions. The definition of real-time depends on
the application under study, ranging from answer time of μs up to several hours in case
of very computing intensive task. During this conference we presented our work in low
level triggers [1] [2] and high level triggers [3] in high energy physics experiments, and
specific application for nuclear magnetic resonance (NMR) [4] [5] and cone-beam CT [6].
Apart from the study of dedicated solution to decrease the latency due to data transport
and preparation, the computing algorithms play an essential role in any GPU application.
In this contribution, we show an original algorithm developed for triggers application, to
accelerate the ring reconstruction in RICH detector when it is not possible to have seeds
for reconstruction from external trackers
First evidence of luminescence in a He/CF gas mixture induced by non-ionizing electrons
Optical readout of Gas Electron Multipliers (GEM) provides very interesting
performances and has been proposed for different applications in particle
physics. In particular, thanks to its good efficiency in the keV energy range,
it is being developed for low-energy and rare event studies, such as Dark
Matter search. So far, the optical approach exploits the light produced during
the avalanche processes in GEM channels. Further luminescence in the gas can be
induced by electrons accelerated by a suitable electric field. The CYGNO
collaboration studied this process with a combined use of a triple-GEM
structure and a grid in an He/CF (60/40) gas mixture at atmospheric
pressure. Results reported in this paper allow to conclude that with an
electric field of about 11~kV/cm a photon production mean free path of about
1.0~cm was found
Directional dark matter searches with the CYGNO project
The goal of the CYGNO project is to deploy at Laboratori Nazionali del Gran Sasso (LNGS) an high resolution Time Projection Chamber (TPC) with Gas Electron Multipliers (GEMs) amplification and optical 3D readout of an Helium/Fluorine based gas mixture for directional Dark Matter (DM) searches at low 1-10 GeV WIMP masses. The determination of the incoming direction of WIMP particles can in fact offer not only additional handles for discrimination of the annoying backgrounds, but especially an unique key for a positive, unambiguous identification of a DM signal
Emulsion sheet doublets as interface trackers for the OPERA experiment
New methods for efficient and unambiguous interconnection between electronic
counters and target units based on nuclear photographic emulsion films have
been developed. The application to the OPERA experiment, that aims at detecting
oscillations between mu neutrino and tau neutrino in the CNGS neutrino beam, is
reported in this paper. In order to reduce background due to latent tracks
collected before installation in the detector, on-site large-scale treatments
of the emulsions ("refreshing") have been applied. Changeable Sheet (CSd)
packages, each made of a doublet of emulsion films, have been designed,
assembled and coupled to the OPERA target units ("ECC bricks"). A device has
been built to print X-ray spots for accurate interconnection both within the
CSd and between the CSd and the related ECC brick. Sample emulsion films have
been extensively scanned with state-of-the-art automated optical microscopes.
Efficient track-matching and powerful background rejection have been achieved
in tests with electronically tagged penetrating muons. Further improvement of
in-doublet film alignment was obtained by matching the pattern of low-energy
electron tracks. The commissioning of the overall OPERA alignment procedure is
in progress.Comment: 19 pages, 19 figure
CYGNO Conceptual Design Report
The conceptual design of the experiment named CYGNO (a CYGNUs module withOptical readout) is presented here. CYGNO aims to make significant advances in the technology of single phase gas-only time projection chambers (TPC) for the specific application of rare scattering events detection. In particular it will focus on a read-out technique based on the GEM amplification of the ionisation and on the visible light collection with a sub-mm position resolution by sCMOS camera. This type of readout - in conjunction with a fast light detection - will allow to reconstruct three dimensional (3D) images of the recoiling particles with high precision, offering new ways to distinguish the electron and nuclear recoils. The recoil direction resolution is also being investigated as a further tool to reject neutral background in the detection of Galactic Dark Matter (DM) particles. The final goal is to build and operate a high resolution gas TPC detector at the 50 kg scale for the directional search of a DM signal, in underground Laboratori Nazionali del Gran Sasso. In order to achieve this very demanding goal, we are going to develop firstly a 1 m3 volume, 1 kg mass detector based on these concepts, to assess on a real underground experiment the design performances and capabilities of our approach, while at the same time testing innovative techniques and methods to reach the 50 kg scale. This project is part of the world-wide effort of the CYGNUS collaboration to define an optimal DM detection scheme sensitive to DM direction, towards a one-ton gas TPC nuclear recoils Sobservatory
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