1,432 research outputs found
Two-jet inclusive cross sections in heavy-ion collisions in the perturbative QCD
In the framework of perturbative QCD, double inclusive cross sections for
high parton production in nucleus-nucleus collisions are computed with
multiple rescattering taken into account. The induced long-range correlations
between numbers of jets at forward and backward rapidities are found to reach
% for light nuclei at GeV/c and to be suppressed for
heavy nuclei and LHC energies.Comment: 17 pages, 6 figures. V2: Major revision
Anisotropic Flow from RHIC to the LHC
Anisotropic flow is recognized as one of the main observables providing
information on the early stage of a heavy-ion collision. At RHIC the large
observed anisotropic flow and its successful description by ideal hydrodynamics
is considered evidence for an early onset of thermalization and almost ideal
fluid properties of the produced strongly coupled Quark Gluon Plasma. This
write-up discusses some key RHIC anisotropic flow measurements and for
anisotropic flow at the LHC some predictions.Comment: 4 pages, 6 figures, hotquarks 200
Automated distal coronary bypass with a novel magnetic coupler (MVP system)
AbstractObjectiveWe sought to assess the feasibility of performing sutureless distal coronary artery bypass anastomoses with a novel magnetic coupling device.MethodsFrom May 2000 to April 2001, single-vessel side-to-side coronary artery bypass grafting on a beating heart was performed in 39 domestic white pigs (35-60 kg) without the use of mechanical stabilization, shunts, or perfusion bridges. Animals were divided into 2 groups. Seventeen pigs underwent right internal thoracic artery to right coronary artery bypass grafting through a median sternotomy (group 1) with a novel magnetic vascular positioning system (MVP system; Ventrica, Inc, Fremont, Calif). Twenty-two pigs underwent left internal thoracic artery to left anterior descending artery grafting with the MVP anastomotic device through a left anterior minithoracotomy (group 2). This system consists of 2 pairs of elliptical magnetic implants and a deployment device. One pair of magnets forms the anastomotic docking port within the graft; the other pair forms an identical anastomotic docking port within the target vessel. The anastomosis is created when the 2 docking ports magnetically couple. Anastomotic patency was evaluated by means of angiography during the first postoperative week and at 1 month. Histologic studies were performed at different time points as late as 6 months.ResultsRight internal thoracic artery to right coronary artery anastomoses and left internal thoracic artery to left anterior descending artery anastomoses were successfully performed with the system in all animals. The self-adherent and self-aligning properties of the implants allowed for immediate and secure approximation of the arteries (total anastomotic time between 2-3 minutes). Anastomoses were constructed without a stabilization platform. Five nondevice-related deaths occurred postoperatively. One-week angiography, performed in 35 surviving animals, showed a patent graft and anastomosis in all cases. The patency rate at 1 month was 97% (33/34). Histologic studies as late as 6 months demonstrated neointimal coverage of the magnets without any significant luminal obstruction. Histology also confirmed the presence of viable tissue between magnets.ConclusionThe MVP anastomotic system uses magnetic force to create rapid and secure distal coronary artery anastomoses, which might facilitate minimally invasive and totally endoscopic coronary artery bypass surgery
Nontangential limits and Fatou-type theorems on post-critically finite self-similar sets
In this paper we study the boundary limit properties of harmonic functions on
, the solutions to the Poisson equation where is a p.c.f. set
and its Laplacian given by a regular harmonic structure. In
particular, we prove the existence of nontangential limits of the corresponding
Poisson integrals, and the analogous results of the classical Fatou theorems
for bounded and nontangentially bounded harmonic functions.Comment: 22 page
Video-assisted thoracoscopic lobectomy: which patients require postoperative physiotherapy?
Objectives: Following major thoracic surgery physiotherapy is recommended to improve reduced lung volume, aid secretion clearance, and improve mobility, however, in many centres physiotherapy provision is variable following minimally invasive video-assisted thoracoscopic surgery (VATS). The objective of this study was to observe frequency of problems potentially amenable to physiotherapy following VATS lobectomy, and to identify associated baseline factors of patients in whom physiotherapy may be beneficial. Methods: A prospective observational study was performed including all consecutive cancer patients undergoing VATS lobectomy in a regional centre over 4 years (2012–2016). Standard postoperative care included early mobilisation by nursing staff from postoperative day one (POD1). Physiotherapy assessment of all patients on POD1 determined presence of issues potentially amenable to physiotherapy intervention, and treatment was commenced. Outcome measures included postoperative pulmonary complication (PPC) development, hospital and high dependency unit (HDU) length of stay (LOS). Results: Of 285 patients, 209 (73%) received physiotherapy to assist/improve reduced mobility, of these 23 (8%) also received sputum clearance therapies and 65 (23%) specific therapy for lung volume loss. The remaining 76 (27%) patients had significantly lower hospital/HDU LOS (P < 0.001) reflecting uncomplicated recovery. Chronic obstructive pulmonary disease (COPD), body mass index (BMI), preoperative mobility and age were independently associated with issues potentially amenable to physiotherapy (P = 0.013). Conclusion: Following VATS lobectomy a large proportion of patients demonstrated issues potentially amenable to physiotherapy. The authors recommend that patients receive routine physiotherapy assessment following this type of surgery to ensure that all issues are identified early. Screening of COPD, BMI, preoperative mobility and age will allow early identification of patients who may benefit most from postoperative physiotherapy and preoperative optimisation, however, these factors cannot predict the need for physiotherapy
Dynamical parton distributions of the nucleon and very small-x physics
Utilizing recent DIS measurements (F_{2,L}) and data on dilepton and
high-E_{T} jet production we determine the dynamical parton distributions of
the nucleon generated radiatively from valence-like positive input
distributions at optimally chosen low resolution scales. These are compared
with `standard' distributions generated from positive input distributions at
some fixed and higher resolution scale. It is shown that up to the next to
leading order NLO(\bar{MS}, DIS) of perturbative QCD considered in this paper,
the uncertainties of the dynamical distributions are, as expected, smaller than
those of their standard counterparts. This holds true in particular in the
presently unexplored extremely small-x region relevant for evaluating ultrahigh
energy cross sections in astrophysical applications. It is noted that our new
dynamical distributions are compatible, within the presently determined
uncertainties, with previously determined dynamical parton distributions.Comment: 21 pages, 2 tables, 16 figures, v2: added Ref.[60], replaced Fig.
Evidence for SU(3) symmetry breaking from hyperon production
We examine the SU(3) symmetry breaking in hyperon semileptonic decays (HSD)
by considering two typical sets of quark contributions to the spin content of
the octet baryons: Set-1 with SU(3) flavor symmetry and Set-2 with SU(3) flavor
symmetry breaking in HSD. The quark distributions of the octet baryons are
calculated with a successful statistical model. Using an approximate relation
between the quark fragmentation functions and the quark distributions, we
predict polarizations of the octet baryons produced in annihilation
and semi-inclusive deeply lepton-nucleon scattering in order to reveal the
SU(3) symmetry breaking effect on the spin structure of the octet baryons. We
find that the SU(3) symmetry breaking significantly affects the hyperon
polarization. The available experimental data on the polarization
seem to favor the theoretical predictions with SU(3) symmetry breaking. We
conclude that there is a possibility to get a collateral evidence for SU(3)
symmetry breaking from hyperon production. The theoretical errors for our
predictions are discussed.Comment: 3 tables, 14 figure
Natural Theories of Ultra-Low Mass PNGB's: Axions and Quintessence
We consider the Wilson Line PNGB which arises in a U(1)^N gauge theory,
abstracted from a latticized, periodically compactified extra dimension U(1).
Planck scale breaking of the PNGB's global symmetry is suppressed, providing
natural candidates for the axion and quintessence. We construct an explicit
model in which the axion may be viewed as the 5th component of the U(1)_Y gauge
field in a 1+4 latticized periodically compactified extra dimension. We also
construct a quintessence PNGB model where the ultra-low mass arises from
Planck-scale suppressed physics itself.Comment: 20 pages, fixed typo and reference
Nonlocal Equation of State in Anisotropic Static Fluid Spheres in General Relativity
We show that it is possible to obtain credible static anisotropic spherically
symmetric matter configurations starting from known density profiles and
satisfying a nonlocal equation of state. These particular types of equation of
state describe, at a given point, the components of the corresponding
energy-momentum tensor not only as a function at that point, but as a
functional throughout the enclosed configuration. To establish the physical
plausibility of the proposed family of solutions satisfying nonlocal equation
of state, we study the constraints imposed by the junction and energy
conditions on these bounded matter distributions.
We also show that it is possible to obtain physically plausible static
anisotropic spherically symmetric matter configurations, having nonlocal
equations of state\textit{,}concerning the particular cases where the radial
pressure vanishes and, other where the tangential pressures vanishes. The later
very particular type of relativistic sphere with vanishing tangential stresses
is inspired by some of the models proposed to describe extremely magnetized
neutron stars (magnetars) during the transverse quantum collapse.Comment: 21 pages, 1 figure, minor changes in the text, references added, two
new solutions studie
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