1,336 research outputs found
Gap formation in helical edge states with magnetic impurities
Helical edge states appear at the surface of two dimensional topological
insulators and are characterized by spin up traveling in one direction and the
spin down traveling in the opposite direction. Such states are protected by
time reversal symmetry and no backscattering due to scalar impurities can
occur. However, magnetic impurities break time reversal symmetry and lead to
backscattering. Often their presence is unintentional, but in some cases they
are introduced into the sample to open up gaps in the spectrum. We investigate
the influence of random impurities on helical edge states, specifically how the
gap behaves in the realistic case of impurities having both a magnetic and a
scalar component. It turns out that for a fixed magnetic contribution the gap
closes when either the scalar component, or Fermi velocity is increased. We
compare diagrammatic techniques in the self-consistent Born approximation to
numerical calculations which yields good agreement. For experimentally relevant
parameters we find that even moderate scalar components can be quite
detrimental for the gap formation.Comment: 6 pages, 6 figure
Tailoring Chirp in Spin-Lasers
The usefulness of semiconductor lasers is often limited by the undesired
frequency modulation, or chirp, a direct consequence of the intensity
modulation and carrier dependence of the refractive index in the gain medium.
In spin-lasers, realized by injecting, optically or electrically,
spin-polarized carriers, we elucidate paths to tailoring chirp. We provide a
generalized expression for chirp in spin-lasers and introduce modulation
schemes that could simultaneously eliminate chirp and enhance the bandwidth, as
compared to the conventional (spin-unpolarized) lasers.Comment: 4 pages, 3 figure
Minimum entropy production principle from a dynamical fluctuation law
The minimum entropy production principle provides an approximative
variational characterization of close-to-equilibrium stationary states, both
for macroscopic systems and for stochastic models. Analyzing the fluctuations
of the empirical distribution of occupation times for a class of Markov
processes, we identify the entropy production as the large deviation rate
function, up to leading order when expanding around a detailed balance
dynamics. In that way, the minimum entropy production principle is recognized
as a consequence of the structure of dynamical fluctuations, and its
approximate character gets an explanation. We also discuss the subtlety
emerging when applying the principle to systems whose degrees of freedom change
sign under kinematical time-reversal.Comment: 17 page
Dissociative electron attachment and vibrational excitation of : Effect of two vibrational modes revisited
We present a study of dissociative electron attachment and vibrational
excitation processes in electron collisions with the CFCl molecule. The
calculations are based on the two-dimensional nuclear dynamics including the
C-Cl symmetric stretch coordinate and the CF symmetric deformation
(umbrella) coordinate. The complex potential energy surfaces are calculated
using the ab initio R-matrix method. The results for dissociative attachment
and vibrational excitation of the umbrella mode agree quite well with
experiment while the cross section for excitation of the C-Cl symmetric stretch
vibrations is about a factor of three low as compared to experimental data.Comment: 24 pages, 7 figures, submitted to Physical Review
Minimally-invasive technologies in the treatment of choledocholithiasis complicated by biliary pancreatitis
Minimal invasive endoscopic technologies are used in the treatment of patients with biliary pancreatitis with complicated cholangitis and biliary sepsis. 56 patients were treated for the period 2014 - 2018, aged 65.5 ± 15.18 years. ERCP was performed in 31 (55,3%) patients, in 13 (23,2%) - surgical intervention was performed without contrast of extrahepatic bile ducts. Papillotomy in 52 cases (96,4%) was performed by string papilloma and in 4 (7,1%) - by needle. In all cases, subtotal papilloprotectomy was performed [1], supplemented by balloon sphincteroplasty. In the I group, the patients included patients with biliary pancreatitis clinic, in group II patients with clinic of biliary sepsis, in the III group patients with purulent cholangitis clinic, biliary sepsis and septic shock. In the 1st and 2nd groups of patients, mortality was not observed. In the 3rd group, 3 patients died (37,5%). The rest of the patients are discharged from the hospital in a satisfactory condition. A decrease in the level of markers of hepatitis cytolysis (AlAT, AsAT, GGTP, L-FABP) was observed during surgical procedures without ERCP, indicating the toxic effect of contrast on the liver parenchyma. L-FABP is a highly informative marker for hepatocyte cytolysis and can be used as a criterion for hepatic insufficiency and prognosis of biliary sepsis. The high efficiency of transpacillary endoscopic surgical techniques in the treatment of biliary pancreatitis and biliary sepsis was noted
Minimally-invasive technologies in the treatment of choledocholithiasis complicated by purulent cholangitis
Minimal invasive endoscopic technologies are used in the treatment of patients with choledocholithiasis with complicated cholangitis and biliary sepsis. 56 patients were treated for the period 2014 - 2018, aged 65.5 ± 15.18 years. ERCP was performed in 31 (55,3%) patients, in 13 (23,2%) - surgical intervention was performed without contrast of extrahepatic bile ducts. Papillotomy in 52 cases (96,4%) was performed by string papilloma and in 4 (7,1%) - by needle. In all cases, subtotal papilloprotectomy was performed [1], supplemented by balloon sphincteroplasty. In the I group, the patients included patients with acute cholangitis clinic, in group II patients with clinic of biliary sepsis, in the III group patients with purulent cholangitis clinic, biliary sepsis and septic shock. In the 1st and 2nd groups of patients, mortality was not observed. In the 3rd group, 3 patients died (37,5%). The rest of the patients are discharged from the hospital in a satisfactory condition. A decrease in the level of markers of hepatitis cytolysis (AlAT, AsAT, GGTP, L-FABP) was observed during surgical procedures without ERCP, indicating the toxic effect of contrast on the liver parenchyma. L-FABP is a highly informative marker for hepatocyte cytolysis and can be used as a criterion for hepatic insufficiency and prognosis of biliary sepsis. The high efficiency of transpacillary endoscopic surgical techniques in the treatment of cholangitis and biliary sepsis was noted
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Fuel Summary for Peach Bottom Unit 1 High-Temperature Gas-Cooled Reactor Cores 1 and 2
This fuel summary report contains background and summary information for the Peach Bottom Unit 1, High-Temperature, Gas-Cooled Reactor Cores 1 and 2. This report contains detailed information about the fuel in the two cores, the Peach Bottom Unit 1 operating history, nuclear parameters, physical and chemical characteristics, and shipping and storage canister related data. The data in this document have been compiled from a large number of sources and are not qualified beyond the qualification of the source documents. This report is intended to provide an overview of the existing data pertaining to spent fuel management and point to pertinent reference source documents. For design applications, the original source documentation must be used. While all referenced sources are available as records or controlled documents at the Idaho National Engineering and Environmental Laboratory (INEEL), some of the sources were marked as informal or draft reports. This is noted where applicable. In some instances, source documents are not consistent. Where they are known, this document identifies those instances and provides clarification where possible. However, as stated above, this document has not been independently qualified and such clarifications are only included for information purposes. Some of the information in this summary is available in multiple source documents. An effort has been made to clearly identify at least one record document as the source for the information included in this report
Z-graded weak modules and regularity
It is proved that if any Z-graded weak module for vertex operator algebra V
is completely reducible, then V is rational and C_2-cofinite. That is, V is
regular. This gives a natural characterization of regular vertex operator
algebras.Comment: 9 page
Origin Of The Far Off-Axis GRB171205A
We show that observed properties of the low luminosity GRB171205A and its
afterglow, like those of most other low-luminosity (LL) gamma ray bursts (GRBs)
associate with a supernova (SN), indicate that it is an ordinary SN-GRB, which
was produced by inverse Compton scattering of glory light by a highly
relativistic narrowly collimated jet ejected in a supernova explosion and
viewed from a far off-axis angle. As such, VLA/VLBI follow-up radio
observations of a superluminal displacement of its bright radio afterglow from
its parent supernova, will be able to test clearly whether it is an ordinary
SN-GRB viewed from far off-axis or it belongs to a distinct class of GRBs,
which are different from ordinary GRBs, and cannot be explained by standard
fireball models of GRBs as ordinary GRBsComment: 5 pages, 6 figures, updated data in Fig. 3, Corrected GRB angular
distance used in Fig.
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