661 research outputs found
Meta-analysis of Randomized Trials Comparing Carotid Endarterectomy and Endovascular Treatment
Hybrid-procedures for the Treatment of Thoracoabdominal Aortic Aneurysms and Dissections
AimThe conventional open repair of thoracoabdominal aneurysms and dissections remains complex and demanding and is associated with significant morbidity and mortality. We present our experience of hybrid open and endovascular treatment of thoracoabdominal aneurysms and dissections.MethodsWithin an experience of 226 aortic stent-grafts between 1998 and April 2006, 6 of the patients (median age 60 years, range 35 to 68 years) with thoracoabdominal aneurysms (Crawford type I, II, III, and V) were treated with a combined endovascular and open surgical approach. Five men and one woman, with median aneurysm diameter of 75mm (range 70â100mm), received revascularization of the renal arteries, the superior mesenteric artery, and the coeliac trunk accomplished via transperitoneal bypass grafting. Aneurysmal exclusion was then performed by stent-graft deployment.ResultsThe entire procedure was technically successful in all patients. The patients were discharged a median of 9 days after the operation, while the postoperative studies revealed the patency of the vessels and no evidence of type I endoleak or secondary rupture of the aneurysm. During follow up (1 to 22 months) spiral-CT scanning revealed distinct shrinkage of the aneurysm, no graft migration or endoleak and patency of all revascularised vessels, except one renal artery in two patients. No patient experienced any temporary or permanent neurological deficit, and no dialysis was necessary.ConclusionThe combined endovascular and open surgical approach is feasible, without cross clamping of the aorta and with minimized ischemia time for renal and visceral arteries, and seems to be an appropriate strategy for patients with a thoraco-abdominal aortic aneurysm or dissection
Power considerations towards a sustainable pan-european network
Energy savings are observed and quantified in the Pan-European network using transparent optical network technology. The network was dimensioned, using realistic traffic predictions of the optical networking roadmap of the European project BONE
MILOPrOductIOn Of vIabLe Miscanthus gigantheus rhIzOMes at fertILe and degraded sOIL
abstract ArAndjelovic, M., G. drAzic, j. MilovAnovic and S. AlekSic, 2014. Miloproduction of viable Miscanthus gigantheus rhizomes at fertile and degraded soil. Bulg. J. Agric. Sci., 20: 1189-1194 expanding supplies of home grown biomass and facilitation of the development and competitiveness of a supply chain in an sustainable manner, presents a core of government's strategy, for energy development in republic of Serbia. Growing agroenergy corps may be one of the solutions according to analysis that were carried out. one of these corps that was found to be especially amenable due to its potentially high productivity and cultivation on degraded terrain is Miscanthus giganteus. The possibility of producing after mentioned plant for the biomass supply chain, at very low cost is the main aim of this study. due to its sterility Miscanthus giganteus can only by propagated by vegetative division. Potential of production of viable rhizome on terrains with different rate of fertility was followed by method of experiments on the field. 6 parameters that were following growth of the rhizome and planting survival rate were monitored. According to the results, main factors that affect production of viable rhizomes are age of mother plants, and biotic effects of weed vegetation. Size of rhizomes and nursery fertilization shoved significantly smaller effect. This study concentrates on available data regarding the potential directions by which Miscanthus material could achieve maximum production, by high density planting
Dimensioning the future pan-European optical network with energy efficiency considerations
This paper studies the overall energy consumption of a pan-European optical transport network for three different time periods: today and in five and ten years from now. In each time period the pan-European network was dimensioned using traffic predictions based on realistic data generated by the optical networking roadmap developed in the framework of the European project Building the Future Optical Network in Europe-BONE. A wavelength routed wavelength division multiplexed optical network based on either transparent or opaque node architectures was examined considering exclusively either 10 Gbit/s or 40 Gbit/s per channel data rates. The results manifest that transparent optical networking technologies are expected to provide significant energy savings of the order of 35% to 55%. It was also shown that the migration towards higher data rates, i.e., from 10 Gbit/s to 40 Gbit/s, is assisting in improving the overall energy efficiency of the network
Prospects for a Dark Matter annihilation signal towards the Sagittarius dwarf galaxy with ground based Cherenkov telescopes
Dwarf galaxies are widely believed to be among the best targets for indirect
dark matter searches using high-energy gamma rays; and indeed gamma-ray
emission from these objects has long been a subject of detailed study for
ground-based atmospheric Cherenkov telescopes. Here, we update current
exclusion limits obtained on the closest dwarf, the Sagittarius dwarf galaxy,
in light of recent realistic dark matter halo models. The constraints on the
velocity-weighted annihilation cross section of the dark matter particle are of
a few 10 cms in the TeV energy range for a 50 h exposure.
The limits are extrapolated to the sensitivities of future Cherenkov Telescope
Arrays. For 200 h of observation time, the sensitivity at 95% C.L. reaches
10 cms. Possible astrophysical backgrounds from gamma-ray
sources dissembled in Sagittarius dwarf are studied. It is shown that with
long-enough observation times, gamma-ray background from millisecond pulsars in
a globular cluster contained within Sagittarius dwarf may limit the sensitivity
to dark matter annihilations.Comment: 12 pages, 5 figures, 2 tables, accepted for publication in Ap
Dark Energy Survey year 1 results: Cosmological constraints from galaxy clustering and weak lensing
We present cosmological results from a combined analysis of galaxy clustering and weak gravitational lensing, using 1321ââdeg2 of griz imaging data from the first year of the Dark Energy Survey (DES Y1). We combine three two-point functions: (i) the cosmic shear correlation function of 26 million source galaxies in four redshift bins, (ii) the galaxy angular autocorrelation function of 650,000 luminous red galaxies in five redshift bins, and (iii) the galaxy-shear cross-correlation of luminous red galaxy positions and source galaxy shears. To demonstrate the robustness of these results, we use independent pairs of galaxy shape, photometric-redshift estimation and validation, and likelihood analysis pipelines. To prevent confirmation bias, the bulk of the analysis was carried out while âblindâ to the true results; we describe an extensive suite of systematics checks performed and passed during this blinded phase. The data are modeled in flat ÎCDM and wCDM cosmologies, marginalizing over 20 nuisance parameters, varying 6 (for ÎCDM) or 7 (for wCDM) cosmological parameters including the neutrino mass density and including the 457Ă457 element analytic covariance matrix. We find consistent cosmological results from these three two-point functions and from their combination obtain S8âĄÏ8(Ωm/0.3)0.5=0.773+0.026â0.020 and Ωm=0.267+0.030â0.017 for ÎCDM; for wCDM, we find S8=0.782+0.036â0.024, Ωm=0.284+0.033â0.030, and w=â0.82+0.21â0.20 at 68% C.L. The precision of these DES Y1 constraints rivals that from the Planck cosmic microwave background measurements, allowing a comparison of structure in the very early and late Universe on equal terms. Although the DES Y1 best-fit values for S8 and Ωm are lower than the central values from Planck for both ÎCDM and wCDM, the Bayes factor indicates that the DES Y1 and Planck data sets are consistent with each other in the context of ÎCDM. Combining DES Y1 with Planck, baryonic acoustic oscillation measurements from SDSS, 6dF, and BOSS and type Ia supernovae from the Joint Lightcurve Analysis data set, we derive very tight constraints on cosmological parameters: S8=0.802±0.012 and Ωm=0.298±0.007 in ÎCDM and w=â1.00+0.05â0.04 in wCDM. Upcoming Dark Energy Survey analyses will provide more stringent tests of the ÎCDM model and extensions such as a time-varying equation of state of dark energy or modified gravity
Simultaneous multi-frequency observation of the unknown redshift blazar PG1553+113 in March-April 2008
5 pĂĄginas, 2 figuras, 3 tablas.-- El Pdf del artĂculo es la versiĂłn pre-print: arXiv: arXiv:0911.1088.-- MAGIC Collaboration: et al.The blazar PGâ1553+113 is a well known TeV Îł-ray emitter. In this paper we determine its spectral energy distribution through simultaneous multi-frequency data to study its emission processes. An extensive campaign was carried out between March and April 2008, where optical, X-ray, high-energy (HE) Îł-ray, and very-high-energy (VHE) Îł-ray data were obtained with the KVA, Abastumani, REM, RossiXTE/ASM, AGILE and MAGIC telescopes, respectively. We combine the data to derive the source's spectral energy distribution and interpret its double-peaked shape within the framework of a synchrotron self-Compton model.Major support
from Germanyâs Bundesministerium fšur Bildung, Wissenschaft, Forschung
und Technologie and Max-Planck-Gesellschaft, Italyâs Istituto Nazionale di
Fisica Nucleare (INFN) and Istituto Nazionale di Astrofisica (INAF), and
Spainâs Ministerio de Ciencia e Innovacion is gratefully acknowledged. The
work was also supported by Switzerlandâs ETH Research grant TH34/043,
Polandâs Ministertwo Nauki i Szkolnictwa WyËzszego grant N N203 390834,
and Germanyâs Young Investigator Program of the Helmholtz Gemeinschaft.
This work was also supported by Georgian National Science Foundation grant
GNSF/ST07/4-180. EP acknowledges support from the Italian Space Agency
through grants ASI-INAF I/023/05/0 and ASI I/088/06/0.Peer reviewe
MAGIC observation of the GRBâ080430 afterglow
6 pĂĄginas, 1 figura.-- El Pdf del artĂculo es la versiĂłn pre-print: arXiv:1004.3665v2.-- MAGIC Collaboration: et al.[Context]: Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of gamma-ray bursts during the prompt phase, i.e. the initial burst of high-energy radiation, and during the long-lasting afterglows. In spite of many successes in interpreting these phenomena, there are still several open key questions about the fundamental emission processes, their energetics and the environment.
[Aims]: Independently of specific gamma-ray burst theoretical recipes, spectra in the GeV/TeV range are predicted to be remarkably simple, being satisfactorily modeled with power-laws, and therefore offer a very valuable tool to probe the extragalactic background light distribution. Furthermore, the simple detection of a component at very-high energies, i.e. at ~100âGeV, would solve the ambiguity about the importance of various possible emission processes, which provide barely distinguishable scenarios at lower energies.
[Methods]: We used the results of the MAGIC telescope observation of the moderate resdhift (z ~ 0.76) GRBâ080430 at energies above about 80âGeV, to evaluate the perspective for late-afterglow observations with ground based GeV/TeV telescopes.
[Results]: We obtained an upper limit of F95% CL = 5.5 Ă 10-11âergâcm-2 s-1 for the very-high energy emission of GRBâ080430, which cannot set further constraints on the theoretical scenarios proposed for this object also due to the difficulties in modeling the low-energy afterglow. Nonetheless, our observations show that Cherenkov telescopes have already reached the required sensitivity to detect the GeV/TeV emission of GRBs at moderate redshift (z âČ 0.8), provided the observations are carried out at early times, close to the onset of their afterglow phase.The support of the German BMBF and MPG,
the Italian INFN and Spanish MICINN is gratefully acknowledged. This work
was also supported by ETH Research Grant TH 34/043, by the Polish MNiSzW
Grant N N203 390834, and by the YIP of the Helmholtz Gemeinschaft.Peer reviewe
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