3,289 research outputs found
Management of duodenal trauma
AbstractDuodenal trauma is uncommon but nowadays seen more and more frequently due to the increased automobile accidents and violent events. The management of duodenal trauma can be complicated, especially when massive injury to the pancreatic-duodenal-biliary complex occurs simultaneously. Even the patients receive surgeries in time, multiple postoperative complications and high mortality are common. To know and manage duodenal trauma better, we searched the recent related literature in PubMed by the keywords of duodenal trauma, therapy, diagnosis and abdomen. It shows that because the diagnosis and management are complicated and the mortality is high, duodenal trauma should be treated in time and tactfully. And application of new technology can help improve the management. In this review, we discussed the incidence, diagnosis, management, and complications as well as mortality of duodenal trauma
Constructing minimal telescopers for rational functions in three discrete variables
We present a new algorithm for constructing minimal telescopers for rational
functions in three discrete variables. This is the first discrete
reduction-based algorithm that goes beyond the bivariate case. The termination
of the algorithm is guaranteed by a known existence criterion of telescopers.
Our approach has the important feature that it avoids the potentially costly
computation of certificates. Computational experiments are also provided so as
to illustrate the efficiency of our approach
Half-titanocene 5-t-butyl-2-(1-(arylimino)methyl)quinolin-8-olate chlorides: Synthesis, characterization and ethylene (co-) polymerization behavior
A series of half-titanocene chloride complexes bearing 5-t-butyl-2-(1-(arylimino)methyl)quinolin-8-olate ligands (L), CpTiLCl₂, has been synthesized in acceptable yields by the stoichiometric reaction of CpTiCl₃ with the respective potassium 5-t-butyl-2-(1-(arylimino)methyl)quinolin-8-olate. All half-titanocene complexes were fully characterized by elemental analysis and NMR spectroscopy, and the molecular structures of the representative complexes C1 and C2 were confirmed as pseudo octahedral at titanium by single-crystal X-ray diffraction. When activated with methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all titanium complexes exhibited good activities (up to 4.8 × 10⁵ g mol⁻¹(Ti) h⁻¹) towards ethylene polymerization. The obtained polyethylene exhibited ultra-high molecular weight (up to 11.82 × 10⁵ g mol⁻¹) with narrow polydispersity. Furthermore, effective co-polymerization of ethylene with 1-hexene or 1-octene was achieved with several percentages of co-monomer incorporation in the resultant polyethylenes
Anti-Hyperon polarization in high energy pp collisions with polarized beams
We study the longitudinal polarization of the Sigma_bar and Xi_bar
anti-hyperons in polarized high energy pp collisions at large transverse
momenta, extending a recent study for the Lambda_bar anti-hyperon. We make
predictions by using different parametrizations of the polarized parton
densities and models for the polarized fragmentation functions. Similar to the
Lambda_bar polarization, the Xi_bar0 and Xi_bar+ polarizations are found to be
sensitive to the polarized anti-strange sea in the nucleon. The Sigma_bar- and
Sigma_bar+ polarizations show sensitivity to the light sea quark polarizations,
\Delta \bar u(x) and \Delta \bar d(x), and their asymmetry.Comment: 17 pages, 9 figures,version to appear in PR
Disorder and metal-insulator transitions in Weyl semimetals
The Weyl semimetal (WSM) is a newly proposed quantum state of matter. It has
Weyl nodes in bulk excitations and Fermi arcs surface states. We study the
effects of disorder and localization in WSMs and find three exotic phase
transitions. (I) Two Weyl nodes near the Brillouin zone boundary can be
annihilated pairwise by disorder scattering, resulting in the opening of a
topologically nontrivial gap and a transition from a WSM to a three-dimensional
(3D) quantum anomalous Hall state. (II) When the two Weyl nodes are well
separated in momentum space, the emergent bulk extended states can give rise to
a direct transition from a WSM to a 3D diffusive anomalous Hall metal. (III)
Two Weyl nodes can emerge near the zone center when an insulating gap closes
with increasing disorder, enabling a direct transition from a normal band
insulator to a WSM. We determine the phase diagram by numerically computing the
localization length and the Hall conductivity, and propose that the exotic
phase transitions can be realized on a photonic lattice.Comment: 7 pages with appendix, 6 figure
- …