A model for the dynamics of extensible semiflexible polymers

We present a model for semiflexible polymers in Hamiltonian formulation which interpolates between a Rouse chain and worm-like chain. Both models are realized as limits for the parameters. The model parameters can also be chosen to match the experimental force-extension curve for double-stranded DNA. Near the ground state of the Hamiltonian, the eigenvalues for the longitudinal (stretching) and the transversal (bending) modes of a chain with N springs, indexed by p, scale as lambda_lp ~ (p/N)^2 and lambda_tp ~ p^2(p-1)^2/N^4 respectively for small p. We also show that the associated decay times tau_p ~ (N/p)^4 will not be observed if they exceed the orientational time scale tau_r ~ N^3 for an equally-long rigid rod, as the driven decay is then washed out by diffusive motion.Comment: 28 pages, 2 figure

Особенности функционального состояния почек белых крыс в условиях хронической гипернатриевой диеты

Целью работы было исследование адаптации неповрежденных почек белых крыс к хроническому гипернатриевому рациону. Установлено, что особенности деятельности почек в условиях хронического гипернатриевого рациона не связаны полностью с естественными возрастными изменениями деятельности почек, а обусловлены так же исчерпанием резервных возможностей почечной паренхимыThe purpose of work was research of acclimatization of uninjured kidneys of white rats to a chronic hypersodium ration. It fixed, that features of activity of kidneys in conditions of a chronic hypersodium ration are not depended completely to natural age changes of activity of kidneys, and caused as by exhaustion of reserve opportunities of a renal parenchyma

National scientific capabilities and technological performance: An exploration of emerging industrial relevant research domains.

Today's theories and models on innovation stress the importance of scientific capabilities and science-technology proximity, especially in new emerging fields of economic activity. In this contribution we examine the relationship between national scientific capabilities, the science intensity of technology and technological performance within six promising industrial fields. Our findings reveal that national technological performance is positively associated with scientific capabilities. Countries performing better on a technological level are characterized both by larger numbers of publications and by numbers of involved institutions that exceed average expected values. The latter observation holds for both companies and knowledge generating institutes actively involved in scientific activities. As such, our findings seem to suggest beneficial effects of scientific capabilities shouldered by a multitude of organizations. In addition, higher numbers of patent activity coincide with higher levels of science intensity pointing out the relevance of science 'proximity' when developing technology in newer, emerging fields. Limitations and directions for further research are discussed.Performance; Research; Theory; Models; Model; Innovation; Field; Science; Intensity; Technology; Country; Expected; Value; Companies; Knowledge; Effects;

Crossover behavior for long reptating polymers

We analyze the Rubinstein-Duke model for polymer reptation by means of density matrix renormalization techniques. We find a crossover behavior for a series of quantities as function of the polymer length. The crossover length may become very large if the mobility of end groups is small compared to that of the internal reptons. Our results offer an explanation to a controversy between theory, experiments and simulations on the leading and subleading scaling behavior of the polymer renewal time and diffusion constant.Comment: 4 Pages, RevTeX, and 4 PostScript figures include

Особливості формування етнічного складу селянської верстви Степового Побужжя

In this short paper we sketch a brief introduction to our Krimp algorithm. Moreover, we briefly discuss some of the large body of follow up research. Pointers to the relevant papers are provided in the bibliography

Total energies from variational functionals of the Green function and the renormalized four-point vertex

We derive variational expressions for the grand potential or action in terms of the many-body Green function $G$ which describes the propagation of particles and the renormalized four-point vertex $\Gamma$ which describes the scattering of two particles in many-body systems. The main ingredient of the variational functionals is a term we denote as the $\Xi$-functional which plays a role analogously to the usual $\Phi$-functional studied by Baym (G.Baym, Phys.Rev. 127, 1391 (1962)) in connection with the conservation laws in many-body systems. We show that any $\Xi$-derivable theory is also $\Phi$-derivable and therefore respects the conservation laws. We further set up a computational scheme to obtain accurate total energies from our variational functionals without having to solve computationally expensive sets of self-consistent equations. The input of the functional is an approximate Green function $\tilde{G}$ and an approximate four-point vertex $\tilde{\Gamma}$ obtained at a relatively low computational cost. The variational property of the functional guarantees that the error in the total energy is only of second order in deviations of the input Green function and vertex from the self-consistent ones that make the functional stationary. The functionals that we will consider for practical applications correspond to infinite order summations of ladder and exchange diagrams and are therefore particularly suited for applications to highly correlated systems. Their practical evaluation is discussed in detail.Comment: 21 pages, 10 figures. Physical Review B (accepted

NGC 2362: a Template for Early Stellar Evolution

We present UBVRI photometry for the young open cluster NGC 2362. From analysis of the appropriate color-color and color-magnitude diagrams we derive the fundamental parameters of the NGC 2362 cluster to be: age = 5 (+1-2) Myr, distance = 1480 pc, E(B-V)=0.10 mag. The cluster age was independently determined for both high mass (2.1 - 36Msun) and low mass (0.7 - 1.2Msun) stars with excellent agreement between the ages derived using post-main sequence and pre-main sequence evolutionary tracks for the high and low mass stars respectively. Analysis of this cluster's color-magnitude diagram reveals a well defined pre-main sequence (covering DeltaV ~ 9 magnitudes in V and extending from early A stars to near the hydrogen burning limit) which makes this cluster an ideal laboratory for pre-main sequence evolution studies.Comment: 9 pages, 3 figures, to be published in ApJ

Adiabatic Formation of Rydberg Crystals with Chirped Laser Pulses

Ultracold atomic gases have been used extensively in recent years to realize textbook examples of condensed matter phenomena. Recently, phase transitions to ordered structures have been predicted for gases of highly excited, 'frozen' Rydberg atoms. Such Rydberg crystals are a model for dilute metallic solids with tunable lattice parameters, and provide access to a wide variety of fundamental phenomena. We investigate theoretically how such structures can be created in four distinct cold atomic systems, by using tailored laser-excitation in the presence of strong Rydberg-Rydberg interactions. We study in detail the experimental requirements and limitations for these systems, and characterize the basic properties of small crystalline Rydberg structures in one, two and three dimensions.Comment: 23 pages, 10 figures, MPIPKS-ITAMP Tandem Workshop, Cold Rydberg Gases and Ultracold Plasmas (CRYP10), Sept. 6-17, 201

Phase Coexistence of a Stockmayer Fluid in an Applied Field

We examine two aspects of Stockmayer fluids which consists of point dipoles that additionally interact via an attractive Lennard-Jones potential. We perform Monte Carlo simulations to examine the effect of an applied field on the liquid-gas phase coexistence and show that a magnetic fluid phase does exist in the absence of an applied field. As part of the search for the magnetic fluid phase, we perform Gibbs ensemble simulations to determine phase coexistence curves at large dipole moments, $\mu$. The critical temperature is found to depend linearly on $\mu^2$ for intermediate values of $\mu$ beyond the initial nonlinear behavior near $\mu=0$ and less than the $\mu$ where no liquid-gas phase coexistence has been found. For phase coexistence in an applied field, the critical temperatures as a function of the applied field for two different $\mu$ are mapped onto a single curve. The critical densities hardly change as a function of applied field. We also verify that in an applied field the liquid droplets within the two phase coexistence region become elongated in the direction of the field.Comment: 23 pages, ReVTeX, 7 figure