16,113 research outputs found
Magnetic Exchange Couplings from Noncollinear Spin Density Functional Perturbation Theory
We propose a method for the evaluation of magnetic exchange couplings based
on noncollinear spin-density functional calculations. The method employs the
second derivative of the total Kohn-Sham energy of a single reference state, in
contrast to approximations based on Kohn-Sham total energy differences. The
advantage of our approach is twofold: It provides a physically motivated
picture of the transition from a low-spin to a high-spin state, and it utilizes
a perturbation scheme for the evaluation of magnetic exchange couplings. The
latter simplifies the way these parameters are predicted using
first-principles: It avoids the non-trivial search for different spin-states
that needs to be carried out in energy difference methods and it opens the
possibility of "black-boxifying" the extraction of exchange couplings from
density functional theory calculations. We present proof of concept
calculations of magnetic exchange couplings in the H--He--H model system and in
an oxovanadium bimetallic complex where the results can be intuitively
rationalized.Comment: J.Chem. Phys. (accepted
Hepatic regeneration and growth factors
Nessun abstrac
Use of weaning concentrate in the feeding suckling kids: effects on meat quality
The effect of a feeding supplementation with starter concentrate on “Capretto” meat production and its qualitative characteristics was investigated. The results showed that the effect of concentrate supplementation did not influence the slaughter weight, slaughter and dissection data, tissue composition and meat chemical composition of the pelvic limb. No differences were found for rheological characteristics of LD meat, except cohesiveness values, which were higher in the concentrate group kids
Low-temperature transport through a quantum dot between two superconductor leads
We consider a quantum dot coupled to two BCS superconductors with same gap
energies . The transport properties are investigated by means of
infinite- noncrossing approximation. In equilibrium density of states, Kondo
effect shows up as two sharp peaks around the gap bounds. Application of a
finite voltage bias leads these peaks to split, leaving suppressed peaks near
the edges of energy gap of each lead. The clearest signatures of the Kondo
effect in transport are three peaks in the nonlinear differential conductance:
one around zero bias, another two at biases . This result is
consistent with recent experiment. We also predict that with decreasing
temperature, the differential conductances at biases anomalously
increase, while the linear conductance descends.Comment: replaced with revised versio
A dog model for acetaminophen-induced fulminant hepatic failure.
The development of a large animal model of fulminant hepatic failure produced with acetaminophen that should be useful in the development and evaluation of potential medical therapies for the important clinical problem of fulminant hepatic failure is described. Acetaminophen in dimethyl sulfoxide (600 mg/ml) given as three subcutaneous injections, with the first dose (750 mg/kg body wt) being given at noon, the second dose (200 mg/kg body wt) being given 9 h later, and the third dose (200 mg/kg body wt) being given 24 h after the initial dose consistently produces fulminant hepatic failure in dogs. The dimethyl sulfoxide vehicle, injected intramuscularly, does not influence either animal survival or hepatic function in control-treated dogs. No deaths occur within the first 36 h. By 72 h after initial drug administration, the mortality is 90%. Histopathological and biochemical investigations demonstrate a high degree of hepatocellular necrosis in nonsurviving animals without appreciable damage to the kidneys, lungs, or heart. The drug schedule and preparation outlined avoids the administration of large volumes of vehicle and results in prolonged high levels of acetaminophen in the blood sufficient to induce severe hepatic injury. Ranitidine (120 mg/kg body wt i.m.) given 30 min before each acetaminophen dose significantly reduces the mortality and hepatic necrosis produced using this model. This model satisfies all criteria established by Miller et al. for the production of a suitable large animal model of fulminant acute hepatic failure
A dog model for acetaminophen-induced fulminant hepatic failure.
The development of a large animal model of fulminant hepatic failure produced with acetaminophen that should be useful in the development and evaluation of potential medical therapies for the important clinical problem of fulminant hepatic failure is described. Acetaminophen in dimethyl sulfoxide (600 mg/ml) given as three subcutaneous injections, with the first dose (750 mg/kg body wt) being given at noon, the second dose (200 mg/kg body wt) being given 9 h later, and the third dose (200 mg/kg body wt) being given 24 h after the initial dose consistently produces fulminant hepatic failure in dogs. The dimethyl sulfoxide vehicle, injected intramuscularly, does not influence either animal survival or hepatic function in control-treated dogs. No deaths occur within the first 36 h. By 72 h after initial drug administration, the mortality is 90%. Histopathological and biochemical investigations demonstrate a high degree of hepatocellular necrosis in nonsurviving animals without appreciable damage to the kidneys, lungs, or heart. The drug schedule and preparation outlined avoids the administration of large volumes of vehicle and results in prolonged high levels of acetaminophen in the blood sufficient to induce severe hepatic injury. Ranitidine (120 mg/kg body wt i.m.) given 30 min before each acetaminophen dose significantly reduces the mortality and hepatic necrosis produced using this model. This model satisfies all criteria established by Miller et al. for the production of a suitable large animal model of fulminant acute hepatic failure
Designing arrays of Josephson junctions for specific static responses
We consider the inverse problem of designing an array of superconducting
Josephson junctions that has a given maximum static current pattern as function
of the applied magnetic field. Such devices are used for magnetometry and as
Terahertz oscillators. The model is a 2D semilinear elliptic operator with
Neuman boundary conditions so the direct problem is difficult to solve because
of the multiplicity of solutions. For an array of small junctions in a passive
region, the model can be reduced to a 1D linear partial differential equation
with Dirac distribution sine nonlinearities. For small junctions and a
symmetric device, the maximum current is the absolute value of a cosine Fourier
series whose coefficients (resp. frequencies) are proportional to the areas
(resp. the positions) of the junctions. The inverse problem is solved by
inverse cosine Fourier transform after choosing the area of the central
junction. We show several examples using combinations of simple three junction
circuits. These new devices could then be tailored to meet specific
applications.Comment: The article was submitted to Inverse Problem
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