2,824 research outputs found
Preliminary study of kaonic deuterium X-rays by the SIDDHARTA experiment at DAFNE
The study of the KbarN system at very low energies plays a key role for the
understanding of the strong interaction between hadrons in the strangeness
sector. At the DAFNE electron-positron collider of Laboratori Nazionali di
Frascati we studied kaonic atoms with Z=1 and Z=2, taking advantage of the
low-energy charged kaons from Phi-mesons decaying nearly at rest. The SIDDHARTA
experiment used X-ray spectroscopy of the kaonic atoms to determine the
transition yields and the strong interaction induced shift and width of the
lowest experimentally accessible level (1s for H and D and 2p for He). Shift
and width are connected to the real and imaginary part of the scattering
length. To disentangle the isospin dependent scattering lengths of the
antikaon-nucleon interaction, measurements of Kp and of Kd are needed. We
report here on an exploratory deuterium measurement, from which a limit for the
yield of the K-series transitions was derived: Y(K_tot)<0.0143 and
Y(K_alpha)<0.0039 (CL 90%). Also, the upcoming SIDDHARTA-2 kaonic deuterium
experiment is introduced.Comment: Accepted by Nuclear Physics
X-ray transition yields of low-Z kaonic atoms produced in Kapton
The X-ray transition yields of kaonic atoms produced in Kapton polyimide
(C22H10N2O5) were measured for the first time in the SIDDHARTA experiment.
X-ray yields of the kaonic atoms with low atomic numbers (Z = 6, 7, and 8) and
transitions with high principal quantum numbers (n = 5-8) were determined. The
relative yield ratios of the successive transitions and those of
carbon-to-nitrogen (C:N) and carbon-to-oxygen (C:O) were also determined. These
X-ray yields provide important information for understanding the capture ratios
and cascade mechanisms of kaonic atoms produced in a compound material, such as
Kapton.Comment: Accepted in Nucl. Phys. A (2013
First measurement of kaonic helium-3 X-rays
The first observation of the kaonic 3He 3d - 2p transition was made using
slow K- mesons stopped in a gaseous 3He target. The kaonic atom X-rays were
detected with large-area silicon drift detectors using the timing information
of the K+K- pairs of phi-meson decays produced by the DAFNE e+e- collider. The
strong interaction shift of the kaonic 3He 2p state was determined to be -2+-2
(stat)+-4 (syst) eV.Comment: Accepted for publication in Phys. Lett.
A New Measurement of Kaonic Hydrogen X rays
The system at threshold is a sensitive testing ground for low
energy QCD, especially for the explicit chiral symmetry breaking. Therefore, we
have measured the -series x rays of kaonic hydrogen atoms at the DANE
electron-positron collider of Laboratori Nazionali di Frascati, and have
determined the most precise values of the strong-interaction energy-level shift
and width of the atomic state. As x-ray detectors, we used large-area
silicon drift detectors having excellent energy and timing resolution, which
were developed especially for the SIDDHARTA experiment. The shift and width
were determined to be eV and
eV, respectively. The new
values will provide vital constraints on the theoretical description of the
low-energy interaction.Comment: 5 figures, submitted to Physics Letters
CONGAS: a collaborative ontology development framework based on Named GrAphS
The process of ontology development involves a range of skills and know-how often requiring team work of different people, each of them with his own way of contributing to the definition and formalization of the domain representation. For this reason, collaborative development is an important feature for ontology editing tools, and should take into account the different characteristics of team participants, provide them with a dedicated working environment allowing to express their ideas and creativity, still protecting integrity of the shared work. In this paper we present CONGAS, a collaborative version of the Knowledge Management and Acquisition platform Semantic Turkey which, exploiting the potentialities brought by recent introduction of context management into RDF triple graphs, offers a collaborative environment where proposals for ontology evolution can emerge and coexist, be evaluated by team users, trusted across different perspectives and eventually converged into the main development stream
A European study on decellularized homografts for pulmonary valve replacement: initial results from the prospective ESPOIR Trial and ESPOIR Registry data\u2020
OBJECTIVES: Decellularized pulmonary homografts (DPH) have shown excellent results for pulmonary valve replacement. However, controlled multicentre studies are lacking to date.METHODS: Prospective European multicentre trial evaluating DPH for pulmonary valve replacement. Matched comparison of DPH to bovine jugular vein (BJV) conduits and cryopreserved homografts (CH) considering patient age, type of heart defect and previous procedures.RESULTS: In total, 121 patients (59 female) were prospectively enrolled (August 2014-December 2016), age 21.3 +/- 14.4 years, DPH diameter 24.4 +/- 2.8 mm. No adverse events occurred with respect to surgical handling; there were 2 early deaths (30 + 59 years) due to myocardial failure after multi-valve procedures and no late mortality (1.7% mortality). After a mean follow-up of 2.2 +/- 0.6 years, the primary efficacy end points mean peak gradient (16.1 +/- 12.1 mmHg) and regurgitation (mean 0.25 +/- 0.48, grade 0-3) were excellent. One reoperation was required for recurrent subvalvular stenosis caused by a pericardial patch and 1 balloon dilatation was performed on a previously stented LPA. 100% follow-up for DPH patients operated before or outside the trial (n = 114) included in the ESPOIR Registry, age 16.6 +/- 10.4 years, diameter 24.1 +/- 4.2 mm, follow-up 5.1 +/- 3.0 years. The combined DPH cohort, n = 235, comprising both Trial and Registry data showed significantly better freedom from explantation (DPH 96.7 +/- 2.1%, CH 84.4 +/- 3.2%, P = 0.029 and BJV 82.7 +/- 3.2%, P = 0.012) and less structural valve degeneration at 10 years when matched to CH, n = 235 and BJV, n = 235 (DPH 61.4 +/- 6.6%, CH 39.9 +/- 4.4%, n.s., BJV 47.5 +/- 4.5%, P = 0.029).CONCLUSIONS: Initial results of the prospective multicentre ESPOIR Trial showed DPH to be safe and efficient. Current DPH results including Registry data were superior to BJV and CH.Thoracic Surger
Kaonic hydrogen X-ray measurement in SIDDHARTA
Kaonic hydrogen atoms provide a unique laboratory to probe the kaon-nucleon
strong interaction at the energy threshold, allowing an investigation of the
interplay between spontaneous and explicit chiral symmetry breaking in
low-energy QCD. The SIDDHARTA Collaboration has measured the -series X rays
of kaonic hydrogen atoms at the DANE electron-positron collider of
Laboratori Nazionali di Frascati, and has determined the most precise values of
the strong-interaction induced shift and width of the atomic energy level.
This result provides vital constraints on the theoretical description of the
low-energy interaction.Comment: 11 pages, 7 figures, Nuclear Physics A (in press) Special Issue on
Strangeness Nuclear Physic
Decellularized tissue engineered pericardium as replacement for tricuspid valve in cardiac surgery
Department of Cardiac, Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover Germany and Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Hannover Medical School, Hannover, Germany, The 6th International Medical Congress for Students and Young Doctors, May 12-14, 2016Introduction: Tricuspid valve replacement is the last treatment choice in tricuspid valve
pathology. The choice to insert mechanical or bioprosthetic valve remains controversial. Both prostheses
have some limitations such as infection, risk of thromboembolism, need for life-long anticoagulation or
limited durability. The following study aimed to develop a novel tissue-engineered tricuspid valve based
on decellularized pericardium allograft.
Materials and methods: Fresh ovine pericardium was harvested at the local slaughter house and
decellularized using detergents. For disinfection all samples were treated for 24h with Phosphate
Buffered Solution supplemented with 1% gentamicin and 1% streptomycin. The effectiveness of
decellularization was evaluated by histological staining (hematoxylin-eosin, Movat’s Pentachrom and
Van Gieson), Isolectin B4 staining (a-gal xenoantigen) and by DNA-quantification. Two valvular
leaflets were manufactured out of decellularized pericardium and sutured ex-vivo into the tricuspid
annulus of an ovine heart and suspended on papillary muscles. Hydraulic test were performed to prove
valve competency.
Discussion results: After detergent treatment pericardial tissue has been converted in a cell-free
scaffold as proven by standard histological analysis. Immunofluorescent examinations revealed the
absence of a-gal xenoantigens. DNA-quantification showed a substantial reduction in DNA content
compared to the normal tissue. The alignment of collagenous fibers in decellularized scaffolds appeared
well-preserved and was not affected by detergent decellularization procedure as proven by histological
staining. Graft disinfection and storage in antibiotic solution after decellularization did not affect the
texture of the scaffold. Furthermore, two leaflet structure created out of decellularized pericardium and
surgically sutured in tricuspid position of ovine heart resulted in a competent valve prosthesis.
Conclusion: The present results have shown successful decellularization of the ovine
pericardium using detergents. Decellularized pericardial allograft can be used in cardiac surgery as a
scaffold for valvular tissue engineering or for in-vivo guided tissue regeneration in tricuspid valve
replacement
Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets
This document is the Technical Design Report covering the two large
spectrometer magnets of the PANDA detector set-up. It shows the conceptual
design of the magnets and their anticipated performance. It precedes the tender
and procurement of the magnets and, hence, is subject to possible modifications
arising during this process.Comment: 10 pages, 14MB, accepted by FAIR STI in May 2009, editors: Inti
Lehmann (chair), Andrea Bersani, Yuri Lobanov, Jost Luehning, Jerzy Smyrski,
Technical Coordiantor: Lars Schmitt, Bernd Lewandowski (deputy),
Spokespersons: Ulrich Wiedner, Paola Gianotti (deputy
Unlocking the secrets of the kaon-nucleon/nuclei interactions at low-energies: The SIDDHARTA(-2) and the AMADEUS experiments at the DA Phi NE collider
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