8 research outputs found
Optical properties of the Q1D multiband models -- the transverse equation of motion approach
The electrodynamic features of the multiband model are examined using the
transverse equation of motion approach in order to give the explanation of
several long-standing problems. It turns out that the exact summation of the
most singular terms in powers of leads to the total optical
conductivity which, in the zero-frequency limit, reduces to the results of the
Boltzmann equation, for both the metallic and semiconducting two-band regime.
The detailed calculations are carried out for the quasi-one-dimensional (Q1D)
two-band model corresponding to imperfect charge-density-wave (CDW) nesting. It
is also shown that the present treatment of the impurity scattering processes
gives the DC conductivity of the ordered CDW state in agreement with the
experimental observation. Finally, the DC and optical conductivity are
calculated numerically for a few typical Q1D cases.Comment: 14 pages, 11 figures, to appear in Fizika A (Zagreb
Electronically Induced Anomaly in LO Phonon Dispersion of High - Tc Superconductors
The strong, electronically induced anomaly in the spectrum of the
longitudinal optical (LO) phonons propagating along the main axes of the
CuO plane is tentatively attributed to the oxygen-oxygen charge transfer
between the two oxygens in the plane. It is argued that this charge transfer
can be large and that it is strongly coupled to the zone boundary LO phonons.
The corresponding negative contribution to the free energy is quartic in the LO
phonon amplitude, making the LO phonon unstable through the first order phase
transition, with a concomitant domain structure.Comment: 3 pages, 2 figure
Luttinger Sum Rule in Slave-Particle Theories
The long-standing belief is that the mean-field-like decoupling procedures
applied to the slave-particle representations of the problems with strong local
interaction violate Luttinger sum rule. The number of occupied resonant states
is small and typically equal to the deviation from the sum rule, shedding doubt
on the overall results. It is therefore illustrated, on the example of the
Emery model for the high-Tc superconductors, that, through the consistent
application of the mean-field procedure to the Hamiltonian and the propagators,
the sum rule is restored and the resonant band conserved. In addition to the
resonant band, the electron spectrum contains large number of occupied states
at the bare site-energy of the ion with strong repulsion. These results can be
straightforwardly generalized to the other similar problems.Comment: 3 page
Therapy Effect of the Stable Gastric Pentadecapeptide BPC 157 on Acute Pancreatitis as Vascular Failure-Induced Severe Peripheral and Central Syndrome in Rats
We revealed the therapy effect of the stable gastric pentadecapeptide BPC 157 (10 μg/kg, 10 ng/kg ig or po) with specific activation of the collateral rescuing pathways, the azygos vein, on bile duct ligation in particular, and acute pancreatitis as local disturbances (i.e., improved gross and microscopy presentation, decreased amylase level). Additionally, we revealed the therapy’s effect on the acute pancreatitis as vascular failure and multiorgan failure, both peripherally and centrally following “occlusion-like” syndrome, major intoxication (alcohol, lithium), maintained severe intra-abdominal hypertension, and myocardial infarction, or occlusion syndrome, and major vessel occlusion. The application-sacrifice periods were ligation times of 0–30 min, 0–5 h, 0–24 h (cured periods, early regimen) and 4.30 h–5 h, 5 h–24 h (cured periods, delayed regimen). Otherwise, bile duct-ligated rats commonly presented intracranial (superior sagittal sinus), portal and caval hypertension and aortal hypotension, gross brain swelling, hemorrhage and lesions, heart dysfunction, lung lesions, liver and kidney failure, gastrointestinal lesions, and severe arterial and venous thrombosis, peripherally and centrally. Unless antagonized with the key effect of BPC 157 regimens, reversal of the inferior caval and superior mesenteric vein congestion and reversal of the failed azygos vein activated azygos vein-recruited direct delivery to rescue the inferior-superior caval vein pathway; these were all antecedent to acute pancreatitis major lesions (i.e., acinar, fat necrosis, hemorrhage). These lesions appeared in the later period, but were markedly attenuated/eliminated (i.e., hemorrhage) in BPC 157-treated rats. To summarize, while the innate vicious cycle may be peripheral (bile duct ligation), or central (rapidly developed brain disturbances), or peripheral and central, BPC 157 resolved acute pancreatitis and its adjacent syndrome