Diffusive high-temperature transport in the one-dimensional Hubbard model

We consider charge and spin transport in the one-dimensional Hubbard model at infinite temperature, half-filling and zero magnetization. Implementing matrix-product-operator simulations of the non-equilibrium steady states of boundary-driven open Hubbard chains for up to 100 sites we find clear evidence of diffusive transport for any (non-zero and finite) value of the interaction U.Comment: 6 pages RevTeX + 8 eps figures; revised and extended versio

Initial-state randomness as a universal source of decoherence

We study time evolution of entanglement between two qubits, which are part of a larger system, after starting from a random initial product state. We show that, due to randomness in the initial product state, entanglement is present only between directly coupled qubits and only for short times. Time dependence of the entanglement appears essentially independent of the specific hamiltonian used for time evolution and is well reproduced by a parameter-free two-body random matrix model.Comment: 8 pages, 6 figure

Hardy's Inequality for the fractional powers of Grushin operator

We prove Hardy's inequality for the fractional powers of the generalized sublaplacian and the fractional powers of the Grushin operator. We also find an integral representation and a ground state representation for the fractional powers of generalized sublaplacian

Pulling a polymer out of a potential well and the mechanical unzipping of DNA

Motivated by the experiments on DNA under torsion, we consider the problem of pulling a polymer out of a potential well by a force applied to one of its ends. If the force is less than a critical value, then the process is activated and has an activation energy proportinal to the length of the chain. Above this critical value, the process is barrierless and will occur spontaneously. We use the Rouse model for the description of the dynamics of the peeling out and study the average behaviour of the chain, by replacing the random noise by its mean. The resultant mean-field equation is a nonlinear diffusion equation and hence rather difficult to analyze. We use physical arguments to convert this in to a moving boundary value problem, which can then be solved exactly. The result is that the time $t_{po}$ required to pull out a polymer of $N$ segments scales like $N^2$. For models other than the Rouse, we argue that $t_{po}\sim N^{1+\nu}$Comment: 11 pages, 6 figures. To appear in PhysicalReview

Our Farewell

The essay describes the founding and first period of operation of the journal Slovenski jezik / Slovene Linguistic Studies as the founding editors hand the journal to a new editorial team.ZRC SAZU, Ljubljana and Hall Center for the Humanities, University of Kansas

Cost variation analysis of oral anti-dyslipidaemic drugs available in Indian pharmaceutical market

Background: Dyslipidaemia is one of major risk factor contributing to cardiovascular disease, which further causes mortality and morbidity, so requires a long course of treatment. Physicians should be aware of the cost of drugs.Methods: Cost of the oral anti-dyslipidaemic drug, either as single drug or in combination manufactured by different pharmaceutical companies in the same strength and dosage form was obtained from current index of medical specialities (CIMS) April-July 2019. The difference in the maximum and minimum price of the same drug manufactured by different pharmaceutical companies and percentage cost variation per 10 tablets was calculated.Results: In this study, existing findings showed a wide cost variation among different brands of the same oral anti-dyslipidaemic drug. Percentage cost variation for individual oral anti-dyslipidaemic drug was found to be highest with atorvastatin (80 mg film coated (FC) tablet): 358.84% followed by atorvastatin (5 mg FC tablet): 247%, fenofibrate  (200 mg FC tablet): 134.22%, lovastatin (10 mg FC tablet): 108.56%, rosuvastatin (10 mg FC tablet): 78.60%,   while lowest cost variation is seen with rosuvastatin 40 mg FC Tb: 1.598%. Among fixed dose combination therapy percentage cost variation was found to be highest with atorvastatin and fenofibrate (10 mg and 160 mg, FC tablet): 256%, followed by atorvastatin and ezetimibe (10 mg and 10 mg, tablet): 132.39%, while minimum cost variation was for rosuvastatin and fenofibrate (10 mg and 67 mg, tablet): 22.6%.Conclusions: These study findings showed that there is a wide variation in the cost of the same oral anti-dyslipidaemic drug. So, it is very necessary for regulatory authorities to regulate the wide variation in the cost, as well as physicians, should be sensitized to be aware of their cost variations to reduce the economic burden of drug-therapy to the patients.