793 research outputs found
Quantum Kinetic Evolution of Marginal Observables
We develop a rigorous formalism for the description of the evolution of
observables of quantum systems of particles in the mean-field scaling limit.
The corresponding asymptotics of a solution of the initial-value problem of the
dual quantum BBGKY hierarchy is constructed. Moreover, links of the evolution
of marginal observables and the evolution of quantum states described in terms
of a one-particle marginal density operator are established. Such approach
gives the alternative description of the kinetic evolution of quantum
many-particle systems to generally accepted approach on basis of kinetic
equations.Comment: 18 page
Towards Rigorous Derivation of Quantum Kinetic Equations
We develop a rigorous formalism for the description of the evolution of
states of quantum many-particle systems in terms of a one-particle density
operator. For initial states which are specified in terms of a one-particle
density operator the equivalence of the description of the evolution of quantum
many-particle states by the Cauchy problem of the quantum BBGKY hierarchy and
by the Cauchy problem of the generalized quantum kinetic equation together with
a sequence of explicitly defined functionals of a solution of stated kinetic
equation is established in the space of trace class operators. The links of the
specific quantum kinetic equations with the generalized quantum kinetic
equation are discussed.Comment: 25 page
Galactose protects against cell damage in mouse models of acute pancreatitis
Acute pancreatitis (AP), a human disease in which the pancreas digests itself, has substantial mortality with no specific therapy. The major causes of AP are alcohol abuse and gallstone complications, but it also occurs as an important side effect of the standard asparaginase-based therapy for childhood acute lymphoblastic leukemia. Previous investigations into the mechanisms underlying pancreatic acinar cell death induced by alcohol metabolites, bile acids, or asparaginase indicated that loss of intracellular ATP generation is an important factor. We now report that, in isolated mouse pancreatic acinar cells or cell clusters, removal of extracellular glucose had little effect on this ATP loss, suggesting that glucose metabolism was severely inhibited under these conditions. Surprisingly, we show that replacing glucose with galactose prevented or markedly reduced the loss of ATP and any subsequent necrosis. Addition of pyruvate had a similar protective effect. We also studied the effect of galactose in vivo in mouse models of AP induced either by a combination of fatty acids and ethanol or asparaginase. In both cases, galactose markedly reduced acinar necrosis and inflammation. Based on these data, we suggest that galactose feeding may be used to protect against AP
On Rigorous Derivation of the Enskog Kinetic Equation
We develop a rigorous formalism for the description of the kinetic evolution
of infinitely many hard spheres. On the basis of the kinetic cluster expansions
of cumulants of groups of operators of finitely many hard spheres the nonlinear
kinetic Enskog equation and its generalizations are justified. It is
established that for initial states which are specified in terms of
one-particle distribution functions the description of the evolution by the
Cauchy problem of the BBGKY hierarchy and by the Cauchy problem of the
generalized Enskog kinetic equation together with a sequence of explicitly
defined functionals of a solution of stated kinetic equation is an equivalent.
For the initial-value problem of the generalized Enskog equation the existence
theorem is proved in the space of integrable functions.Comment: 28 page
The spectral shift function and Levinson's theorem for quantum star graphs
We consider the Schr\"odinger operator on a star shaped graph with edges
joined at a single vertex. We derive an expression for the trace of the
difference of the perturbed and unperturbed resolvent in terms of a Wronskian.
This leads to representations for the perturbation determinant and the spectral
shift function, and to an analog of Levinson's formula
1-Alkoxyamino-4-dimethylaminopyridinium derivatives as new representatives of O–N–N⁺ geminal systems and their structure
Sampling of quantum dynamics at long time
The principle of energy conservation leads to a generalized choice of
transition probability in a piecewise adiabatic representation of
quantum(-classical) dynamics. Significant improvement (almost an order of
magnitude, depending on the parameters of the calculation) over previous
schemes is achieved. Novel perspectives for theoretical calculations in
coherent many-body systems are opened.Comment: Revised versio
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