17,546 research outputs found
Jet quenching and elliptic flow at RHIC and LHC within a pQCD-based partonic transport model
Fully dynamic simulations of heavy ion collisions at RHIC and at LHC energies
within the perturbative QCD-based partonic transport model BAMPS (Boltzmann
Approach to Multi-Parton Scatterings) are presented, focusing on the
simultaneous investigation of jet quenching and elliptic flow. The model
features inelastic 2 3 processes based on the Gunion-Bertsch matrix element
and has recently been extended to include light quark degrees of freedom,
allowing for direct comparison to hadronic data on the nuclear modification
factor via a fragmentation scheme for high-pT partons. The nuclear modification
factor of neutral pions in central Au+Au collisions at RHIC energy is compared
to experimental data. Furthermore first results on the nuclear modification
factor and the integrated elliptic flow of charged hadrons in Pb+Pb collisions
at LHC are presented and compared to recent ALICE data. These investigations
are complemented by a study on the suppression of D-mesons at LHC based on
elastic interactions with the medium.Comment: To appear in the proceedings of Quark Matter 201
Resonant Conversion of Massless Neutrinos in Supernovae
It has been noted for a long time that, in some circumstances, {\sl massless}
neutrinos may be {\sl mixed} in the leptonic charged current. Conventional
neutrino oscillation searches in vacuum are insensitive to this mixing. We
discuss the effects of resonant massless-neutrino conversions in the dense
medium of a supernova. In particular, we show how the detected
energy spectra from SN1987a and the supernova -process nucleosynthesis may
be used to provide very stringent constraints on the mixing of {\sl massless}
neutrinos.Comment: latex file, 20 pages, including 3 postscript figure
LOFT as a discovery machine for jetted Tidal Disruption Events
This is a White Paper in support of the mission concept of the Large
Observatory for X-ray Timing (LOFT), proposed as a medium-sized ESA mission. We
discuss the potential of LOFT for the study of jetted tidal disruption events.
For a summary, we refer to the paper.Comment: White Paper in Support of the Mission Concept of the Large
Observatory for X-ray Timin
Accounting for both electron--lattice and electron--electron coupling in conjugated polymers: minimum total energy calculations on the Hubbard--Peierls hamiltonian
Minimum total energy calculations, which account for both electron--lattice
and electron--electron interactions in conjugated polymers are performed for
chains with up to eight carbon atoms. These calculations are motivated in part
by recent experimental results on the spectroscopy of polyenes and conjugated
polymers and shed light on the longstanding question of the relative importance
of electron--lattice vs. electron--electron interactions in determining the
properties of these systems.Comment: 6 pages, Plain TeX, FRL-PSD-93GR
Eliashberg theory of excitonic insulating transition in graphene
A sufficiently strong Coulomb interaction may open an excitonic fermion gap
and thus drive a semimetal-insulator transition in graphene. In this paper, we
study the Eliashberg theory of excitonic transition by coupling the fermion gap
equation self-consistently to the equation of vacuum polarization function.
Including the fermion gap into polarization function increases the effective
strength of Coulomb interaction because it reduces the screening effects due to
the collective particle-hole excitations. Although this procedure does not
change the critical point, it leads to a significant enhancement of the
dynamical fermion gap in the excitonic insulating phase. The validity of the
Eliashberg theory is justified by showing that the vertex corrections are
suppressed at large limit.Comment: 8 pages, 6 figure
Percutaneous stenting of a dissected superior mesenteric artery in a patient with previous surgical repair of Stanford type a aortic dissection
Background/Aim: We report a case of a 54-year-old male patient with background history of hypertension, which suffered a Stanford type A thoraco-abdominal aortic dissection with extension to the visceral arteries. Description of case: The patient initially underwent surgical repair with replacement of the ascending aorta and of the hemiarch in the acute phase of the dissection. Postoperatively, he developed non-specific abdominal pain that was not related to meals but led to weight loss of 20 kg within the first five post-operative months. Follow-up computerized tomography scan revealed a chronic subphrenic aortic dissection extending to the celiac axis (with involvement of the left gastric and the splenic artery), the left renal artery and the superior mesenteric artery (SMA). The hepatic artery took origin from the SMA and received blood from the true lumen of the vessel, and the right renal artery was entirely supplied from the true aortic lumen. After exclusion of other causes of abdominal pain, the patient was treated with percutaneous stent placement in the dissected SMA with significant improvement of his symptoms. Conclusion: This case report emphasizes the role of visceral artery endovascular techniques in the management of patients with complicated chronic aortic dissectio
D meson nuclear modification factors in Pb-Pb collisions at {\surd}sNN = 2.76 TeV, measured with the ALICE detector
The ALICE experiment has measured the D meson production in pp and Pb-Pb
collisions at the LHC at {\surd}s = 7 and 2.76 TeV and {\surd}sNN = 2.76 TeV
respectively, via the exclusive reconstruction of hadronic decay channels. The
analyses of the D0{\to}K-pi+ and D+{\to}K-pi+pi+ channels will be described and
the preliminary results for the D0 and D+ nuclear modification factor will be
presented.Comment: Proceedings of Quark Matter 2011 conference. 4 pages, 4 figures. The
slides of the talk can be found at the link:
http://indico.cern.ch/materialDisplay.py?contribId=591&sessionId=53&materialId=slides&confId=3024
On the reliability and repeatability of surface electromyography factorization by muscle synergies in daily life activities
Muscle synergy theory is a new appealing approach for different research fields. This study is aimed at evaluating the robustness of EMG reconstruction via muscle synergies and the repeatability of muscle synergy parameters as potential neurophysiological indices. Eight healthy subjects performed walking, stepping, running, and ascending and descending stairs' trials for five repetitions in three sessions. Twelve muscles of the dominant leg were analyzed. The “nonnegative matrix factorization” and “variability account for” were used to extract muscle synergies and to assess EMG goodness reconstruction, respectively. Intraclass correlation was used to quantify methodology reliability. Cosine similarity and coefficient of determination assessed the repeatability of the muscle synergy vectors and the temporal activity patterns, respectively. A 4-synergy model was selected for EMG signal factorization. Intraclass correlation was excellent for the overall reconstruction, while it ranged from fair to excellent for single muscles. The EMG reconstruction was found repeatable across sessions and subjects. Considering the selection of neurophysiological indices, the number of synergies was not repeatable neither within nor between subjects. Conversely, the cosine similarity and coefficient of determination values allow considering the muscle synergy vectors and the temporal activity patterns as potential neurophysiological indices due to their similarity both within and between subjects. More specifically, some synergies in the 4-synergy model reveal themselves as more repeatable than others, suggesting focusing on them when seeking at the neurophysiological index identification
The Near Infrared NaI Doublet Feature in M Stars
The NaI near-infrared doublet has been used to indicate the dwarf/giant
population in composite systems, but its interpretation is still a contentious
issue. In order to understand the behaviour of this controversial feature, we
study the observed and synthetic spectra of cool stars. We conclude that the
NaI infrared feature can be used as a dwarf/giant discriminator. We propose a
modified definition of the NaI index by locating the red continuum at 8234
angstrons and by measuring the equivalent width in the range 8172-8197
angstrons, avoiding the region at lambda > 8197 angstrons, which contains VI,
ZrI, FeI and TiO lines. We also study the dependence of this feature on stellar
atmospheric parameters.Comment: 9 pages, (TeX file) + 7 Figures in Postscript format. Accepted for
publication in The Astrophysical Journa
Extending Adjuvant Endocrine Therapy for 10 Years: A Mixed-Methods Analysis of Women's Decision Making in an Online Breast Cancer Forum
An additional 5 years of treatment with adjuvant hormonal therapy, to complete 10 years of medication, is recommended to reduce the risk of breast cancer recurrence. Yet professionals and patients should balance this benefit against side effects and toxicities. Little is known about women's decision making regarding persistence with extended endocrine therapy. In this study, we collected data from a UK online breast cancer forum to analyse patterns of persistence and its associated factors. A mixed-methods exploratory sequential design was used, with a qualitative analysis of text (n = 61 individuals) informing the development of a quantitative instrument to statistically analyse the prevalence of the findings (n = 130). Our findings identified three different groups of women who had to make decisions regarding persistence with treatment: those about to complete 5 years of therapy, those who decided to extend treatment, and those who were initially prescribed 10 years. Factors affecting persistence were, lack of self-efficacy in managing side effects, lack of reassurance about individual risk of recurrence, and impact on quality of life. Interventions such as training of healthcare professionals including risk communication, medication reviews by clinical pharmacists, and re-planning of services in follow-up care, should better support women's needs in extended hormonal therapy
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