167 research outputs found
Pylephlebitis complicating peridiverticulitis without hepatic abscess: early detection with contrast-enhanced CT of the abdomen
Pylephlebitis is a very rare and dangerous complication of inflammatory abdominal processes, mainly appendicitis (1) and diverticulitis (2). We describe a case of peridiverticular inflammation leading to a extensive phlebitis of the adjacent sigmoid vein, extending to the inferior mesenteric vein up to the proximal portal vein, with distal embolus into the left portal vein. Contrast CT and multiplanar reconstructions allowed early diagnosis, and with antibiotic and anticoagulation therapy, no liver abscess developed
Spontaneous transhepatic rupture of the gallbladder with massive hemoperitoneum.
Perforation of the gallbladder has an incidence of 1.6 to 2.8% in gallbladder disease. Among these cases trans hepatic rupture is a very rare event. We report a case associated with secondary massive hemoperitoneum, free gallstone spillage, partial portal vein thrombosis and secondary pulmonary embolis
Theory of the optical conductivity of (TMTSF)PF in the mid-infrared range
We propose an explanation of the mid-infrared peak observed in the optical
conductivity of the Bechgaard salt (TMTSF)PF in terms of electronic
excitations. It is based on a numerical calculation of the conductivity of the
quarter-filled, dimerized Hubbard model. The main result is that, even for
intermediate values of for which the charge gap is known to be very
small, the first peak, and at the same time the main structure, of the optical
conductivity is at an energy of the order of the dimerization gap, like in the
infinite case. This surprising effect is a consequence of the optical
selection rules.Comment: 10 pages, 9 uuencoded figure
Double Exchange Model for Magnetic Hexaborides
A microscopic theory for rare-earth ferromagnetic hexaborides, such as
Eu(1-x)Ca(x)B6, is proposed on the basis of the double-exchange Hamiltonian. In
these systems, the reduced carrier concentrations place the Fermi level near
the mobility edge, introduced in the spectral density by the disordered spin
background. We show that the transport properties such as Hall effect,
magnetoresitance, frequency dependent conductivity, and DC resistivity can be
quantitatively described within the model. We also make specific predictions
for the behavior of the Curie temperature, Tc, as a function of the plasma
frequency, omega_p.Comment: 4 pages, 3 figure
Extensive propagation of a pancreatic pseudocyst along the lower limb through the sciatic foramen.
The extremely rare extensive propagation of a giant retroperitoneal pancreatic pseudocyst into the posterior compartment of the lower limb as far as the knee is reported. The extension was found producing through the sciatic foramen and the full diagnosis was made by MDCT. A complete healing was progressively obtained in the 78-year old female after a six months period of sequential multidisciplinary therapeutic approach comprising combined medical and surgical intra-abdominal and external drainage
Effect of dialysis membrane and patient's age on signs of dialysis-related amyloidosis
Effect of dialysis membrane and patient's age on signs of dialysis-related amyloidosis. This 12 center study was designed to assess factors affecting the development and progression of β2-microglobulin amyloidosis in long-term dialysis. A total of 221 patients who were on hemodialysis for more than five years, and who were treated the entire time only with AN69, a biocompatible, highly permeable membrane, or cuprophane, a less permeable, poorly biocompatible membrane (Cell) were evaluated for time on dialysis, development of carpal tunnel syndrome, and cystic bone lesions X-ray documentation was taken in a minimum of four of the six following joints: both hips, wrists and shoulders. The data demonstrate that patients treated solely by AN69 membranes display signs of bone amyloidosis less frequently than do those treated by Cell membranes. Age at onset of dialysis was found to have a striking correlation with the development of carpal tunnel syndrome and bone amyloidosis, while no significant influence was found for hyperparathyroidism, sex or year of first dialysis
Finite temperature mobility of a particle coupled to a fermion environment
We study numerically the finite temperature and frequency mobility of a
particle coupled by a local interaction to a system of spinless fermions in one
dimension. We find that when the model is integrable (particle mass equal to
the mass of fermions) the static mobility diverges. Further, an enhanced
mobility is observed over a finite parameter range away from the integrable
point. We present a novel analysis of the finite temperature static mobility
based on a random matrix theory description of the many-body Hamiltonian.Comment: 11 pages (RevTeX), 5 Postscript files, compressed using uufile
Deducing correlation parameters from optical conductivity in the Bechgaard salts
Numerical calculations of the kinetic energy of various extensions of the
one-dimensional Hubbard model including dimerization and repulsion between
nearest neighbours are reported. Using the sum rule that relates the kinetic
energy to the integral of the optical conductivity, one can determine which
parameters are consistent with the reduction of the infrared oscillator
strength that has been observed in the Bechgaard salts. This leads to improved
estimates of the correlation parameters for both the TMTSF and TMTTF series.Comment: 12 pages, latex, figures available from the author
Dynamical mean field theory for transition temperature and optics of CMR manganites
A tight binding parametrization of local spin density functional band theory
is combined with a dynamical mean field treatment of correlations to obtain a
theory of the magnetic transition temperature, optical conductivity and T=0
spinwave stiffness of a minimal model for the pseudocubic metallic
manganites such a . The results indicate that previous
estimates of obtained by one of us (Phys. Rev. \textbf{B61} 10738-49
(2000)) are in error, that in fact the materials are characterized by Hunds
coupling , and that magnetic-order driven changes in the
kinetic energy may not be the cause of the observed 'colossal' magnetoresistive
and multiphase behavior in the manganites, raising questions about our present
understanding of these materials.Comment: Published version; 10 pages, 9 figure
Electrical resistivity at large temperatures: Saturation and lack thereof
Many transition metal compounds show saturation of the resistivity at high
temperatures, T, while the alkali-doped fullerenes and the high-Tc cuprates are
usually considered to show no saturation. We present a model of transition
metal compounds, showing saturation, and a model of alkali-doped fullerenes,
showing no saturation. To analyze the results we use the f-sum rule, which
leads to an approximate upper limit for the resistivity at large T. For some
systems and at low T, the resistivity increases so rapidly that this upper
limit is approached for experimental T. The resistivity then saturates. For a
model of transition metal compounds with weakly interacting electrons, the
upper limit corresponds to a mean free path consistent with the Ioffe-Regel
condition. For a model of the high Tc cuprates with strongly interacting
electrons, however, the upper limit is much larger than the Ioffe-Regel
condition suggests. Since this limit is not exceeded by experimental data, the
data are consistent with saturation also for the cuprates. After "saturation"
the resistivity usually grows slowly. For the alkali-doped fullerenes,
"saturation" can be considered to have happened already for T=0, due to
orientational disorder. For these systems, however, the resistivity grows so
rapidly after "saturation" that this concept is meaningless. This is due to the
small band width and to the coupling to the level energies of the important
phonons.Comment: 22 pages, RevTeX, 19 eps figures, additional material available at
http://www.mpi-stuttgart.mpg.de/andersen/fullerene
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