2,759 research outputs found
A case of pancreatic cancer with concomitant median arcuate ligament syndrome treated successfully using an allograft arterial transposition
An association of pancreatic cancer and median arcuate ligament syndrome (MALS) is a rare and challenging situation in terms of treatment. A 60-year-old man diagnosed with pancreatic cancer underwent laparotomy. A pancreaticoduodenectomy was planned, but during the resection part of the operation, a celiac artery stenosis was noticed. The patient was diagnosed with MALS causing almost total celiac artery occlusion, with no radiological solution. The patient was re-operated the next day, and an iliac artery allograft was used for aorta-proper hepatic artery reconstruction, concomitant with the total pancreaticoduodenectomy. Preoperative meticulous evaluation of vascular structures of the celiac trunk and its branches is important, especially in pancreatic surgery. A vascular allograft may be a lifesaving alternative when vascular reconstruction is necessary
h-deformation of Gr(2)
The -deformation of functions on the Grassmann matrix group is
presented via a contraction of . As an interesting point, we have seen
that, in the case of the -deformation, both R-matrices of and
are the same
Influences of Radiative Heat Transfer on Variation of Cell Voltage within a Stack
ABSTRACT In this study, a numerical investigation of cell-to-cell voltage variation by considering the impact of flow distribution and heat transfer on a stack of cells has been performed. A SOFC stack model has been previously developed to study the influence of flow distribution on stack performanc
Three Millisecond Pulsars in FERMI LAT Unassociated Bright Sources
We searched for radio pulsars in 25 of the non-variable, unassociated sources
in the Fermi LAT Bright Source List with the Green Bank Telescope at 820 MHz.
We report the discovery of three radio and gamma-ray millisecond pulsars (MSPs)
from a high Galactic latitude subset of these sources. All of the pulsars are
in binary systems, which would have made them virtually impossible to detect in
blind gamma-ray pulsation searches. They seem to be relatively normal, nearby
(<=2 kpc) millisecond pulsars. These observations, in combination with the
Fermi detection of gamma-rays from other known radio MSPs, imply that most, if
not all, radio MSPs are efficient gamma-ray producers. The gamma-ray spectra of
the pulsars are power-law in nature with exponential cutoffs at a few GeV, as
has been found with most other pulsars. The MSPs have all been detected as
X-ray point sources. Their soft X-ray luminosities of ~10^{30-31} erg/s are
typical of the rare radio MSPs seen in X-rays.Comment: Accepted for publication in ApJ Letter
The deconfinement transition of finite density QCD with heavy quarks from strong coupling series
Starting from Wilson's action, we calculate strong coupling series for the
Polyakov loop susceptibility in lattice gauge theories for various small N_\tau
in the thermodynamic limit. Analysing the series with Pad\'e approximants, we
estimate critical couplings and exponents for the deconfinement phase
transition. For SU(2) pure gauge theory our results agree with those from
Monte-Carlo simulations within errors, which for the coarser N_\tau=1,2
lattices are at the percent level. For QCD we include dynamical fermions via a
hopping parameter expansion. On a N_\tau=1 lattice with N_f=1,2,3, we locate
the second order critical point where the deconfinement transition turns into a
crossover. We furthermore determine the behaviour of the critical parameters
with finite chemical potential and find the first order region to shrink with
growing \mu. Our series moreover correctly reflects the known Z(N) transition
at imaginary chemical potential.Comment: 18 pages, 7 figures, typos corrected, version published in JHE
How large is "large " for Nuclear matter?
We argue that a so far neglected dimensionless scale, the number of neighbors
in a closely packed system, is relevant for the convergence of the large
expansion at high chemical potential. It is only when the number of colors is
large w.r.t. this new scale (\sim \order{10}) that a convergent large
limit is reached. This provides an explanation as to why the large
expansion, qualitatively successful in in vacuum QCD, fails to describe high
baryo-chemical potential systems, such as nuclear matter. It also means that
phenomenological claims about high density matter based on large
extrapolations should be treated with caution.Comment: Proceedings of CPOD2010 conference, in Dubna. Results based on
Phys.Rev.C82, 055202 (2010), http://arxiv.org/abs/1006.247
Electrophilic Organoiridiunn(III) Pincer Complexes on Sulfated Zirconia for Hydrocarbon Activation and Functionalization
Single-site supported organometallic catalysts bring together the favorable aspects of homogeneous and heterogeneous catalysis while offering opportunities to investigate the impact of metal–support interactions on reactivity. We report a (dmPhebox)Ir(III) (dmPhebox = 2,6-bis(4,4-dimethyloxazolinyl)-3,5-dimethylphenyl) complex chemisorbed on sulfated zirconia, the molecular precursor for which was previously applied to hydrocarbon functionalization. Spectroscopic methods such as diffuse reflectance infrared Fourier transformation spectroscopy (DRIFTS), dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) spectroscopy, and X-ray absorption spectroscopy (XAS) were used to characterize the supported species. Tetrabutylammonium acetate was found to remove the organometallic species from the surface, enabling solution-phase analytical techniques in conjunction with traditional surface methods. Cationic character was imparted to the iridium center by its grafting onto sulfated zirconia, imbuing high levels of activity in electrophilic C–H bond functionalization reactions such as the stoichiometric dehydrogenation of alkanes, with density functional theory (DFT) calculations showing a lower barrier for β-H elimination. Catalytic hydrogenation of olefins was also facilitated by the sulfated zirconia-supported (dmPhebox)Ir(III) complex, while the homologous complex on silica was inactive under comparable conditions
Asteroseismology of the solar analogs 16 Cyg A & B from Kepler observations
The evolved solar-type stars 16 Cyg A & B have long been studied as solar
analogs, yielding a glimpse into the future of our own Sun. The orbital period
of the binary system is too long to provide meaningful dynamical constraints on
the stellar properties, but asteroseismology can help because the stars are
among the brightest in the Kepler field. We present an analysis of three months
of nearly uninterrupted photometry of 16 Cyg A & B from the Kepler space
telescope. We extract a total of 46 and 41 oscillation frequencies for the two
components respectively, including a clear detection of octupole (l=3) modes in
both stars. We derive the properties of each star independently using the
Asteroseismic Modeling Portal, fitting the individual oscillation frequencies
and other observational constraints simultaneously. We evaluate the systematic
uncertainties from an ensemble of results generated by a variety of stellar
evolution codes and fitting methods. The optimal models derived by fitting each
component individually yield a common age (t=6.8+/-0.4 Gyr) and initial
composition (Z_i=0.024+/-0.002, Y_i=0.25+/-0.01) within the uncertainties, as
expected for the components of a binary system, bolstering our confidence in
the reliability of asteroseismic techniques. The longer data sets that will
ultimately become available will allow future studies of differential rotation,
convection zone depths, and long-term changes due to stellar activity cycles.Comment: 6 pages, 2 figures, 2 tables, ApJ Letters (accepted
Asymptotic Regge Trajectories of Non-strange Mesons
We analyze the asymptotic behavior of Regge trajectories of non-strange
mesons. In contrast to an existing belief, it is demonstrated that for the
asymptotically linear Regge trajectories the width of heavy hadrons cannot
linearly depend on their mass. Using the data on masses and widths of rho_J,
omega_J, a_J and f_J mesons for the spin values J \leq 6, we extract the
parameters of the asymptotically linear Regge trajectory predicted by the
finite width model of quark gluon bags. As it is shown the obtained parameters
for the data set B correspond to the cross-over temperature lying in the
interval 170.9-175.3 MeV which is consistent with the kinetic freeze-out
temperature of early hadronizing particles found in relativistic heavy ion
collisions at and above the highest SPS energy.Comment: 14 pages, 3 figure
- …