Scaling properties of step bunches induced by sublimation and related mechanisms: A unified perspective

This work provides a ground for a quantitative interpretation of experiments on step bunching during sublimation of crystals with a pronounced Ehrlich-Schwoebel (ES) barrier in the regime of weak desorption. A strong step bunching instability takes place when the kinetic length is larger than the average distance between the steps on the vicinal surface. In the opposite limit the instability is weak and step bunching can occur only when the magnitude of step-step repulsion is small. The central result are power law relations of the between the width, the height, and the minimum interstep distance of a bunch. These relations are obtained from a continuum evolution equation for the surface profile, which is derived from the discrete step dynamical equations for. The analysis of the continuum equation reveals the existence of two types of stationary bunch profiles with different scaling properties. Through a mathematical equivalence on the level of the discrete step equations as well as on the continuum level, our results carry over to the problems of step bunching induced by growth with a strong inverse ES effect, and by electromigration in the attachment/detachment limited regime. Thus our work provides support for the existence of universality classes of step bunching instabilities [A. Pimpinelli et al., Phys. Rev. Lett. 88, 206103 (2002)], but some aspects of the universality scenario need to be revised.Comment: 21 pages, 8 figure

Equilibrium of anchored interfaces with quenched disordered growth

The roughening behavior of a one-dimensional interface fluctuating under quenched disorder growth is examined while keeping an anchored boundary. The latter introduces detailed balance conditions which allows for a thorough analysis of equilibrium aspects at both macroscopic and microscopic scales. It is found that the interface roughens linearly with the substrate size only in the vicinity of special disorder realizations. Otherwise, it remains stiff and tilted.Comment: 6 pages, 3 postscript figure

Drift causes anomalous exponents in growth processes

The effect of a drift term in the presence of fixed boundaries is studied for the one-dimensional Edwards-Wilkinson equation, to reveal a general mechanism that causes a change of exponents for a very broad class of growth processes. This mechanism represents a relevant perturbation and therefore is important for the interpretation of experimental and numerical results. In effect, the mechanism leads to the roughness exponent assuming the same value as the growth exponent. In the case of the Edwards-Wilkinson equation this implies exponents deviating from those expected by dimensional analysis.Comment: 4 pages, 1 figure, REVTeX; accepted for publication in PRL; added note and reference

Dynamics of a disordered, driven zero range process in one dimension

We study a driven zero range process which models a closed system of attractive particles that hop with site-dependent rates and whose steady state shows a condensation transition with increasing density. We characterise the dynamical properties of the mass fluctuations in the steady state in one dimension both analytically and numerically and show that the transport properties are anomalous in certain regions of the density-disorder plane. We also determine the form of the scaling function which describes the growth of the condensate as a function of time, starting from a uniform density distribution.Comment: Revtex4, 5 pages including 2 figures; Revised version; To appear in Phys. Rev. Let

Internalizing European Court of Human Rights Interpretations: Russia\u27s Courts of General Jurisdiction and New Directions in Civil Defamation Law

The manuscript examines the steps that Russia\u27s courts of general jurisdiction have taken since 2002 to fashion major changes in Russia\u27s civil defamation law. The critical element in this process has been the courts\u27 internalization of the practice of the European Court of Human Rights in interpreting the freedom of expression provisions in Article 10 of the European Convention on Human Rights, to which Russia acceded in 1998. The internalization movement in the Russian courts began in 2002 in isolated lower court decisions, and culminated in a generally-applicable Decree of the Russian Federation Supreme Court in 2005. The manuscript examines a number of those lower court decisions, as well as the 2005 Decree, to identify the substantive changes in defamation law and the process by which the European Court\u27s practice has been used to fashion them. The manuscript also assesses the prospects for the courts’ further extension of the European Court\u27s positions to remaining unresolved questions in civil defamation law. In this inquiry, I seek to identify the methodology for implementation of the Supreme Court\u27s 2005 directive that the lower courts take into account the European Court\u27s practice in deciding defamation disputes

Caspase-10 Is the Key Initiator Caspase Involved in Tributyltin-Mediated Apoptosis in Human Immune Cells

Tributyltin (TBT) is one of the most toxic compounds produced by man and distributed in the environment. A multitude of toxic activities have been described, for example, immunotoxic, neurotoxic, and endocrine disruptive effects. Moreover, it has been shown for many cell types that they undergo apoptosis after treatment with TBT and the cell death of immune cells could be the molecular background of its immunotoxic effect. As low as 200 nM up to 1 μM of TBT induces all signs of apoptosis in Jurkat T cells within 1 to 24 hrs of treatment. When compared to Fas-ligand control stimulation, the same sequence of events occurs: membrane blebbing, phosphatidylserine externalisation, the activation of the “death-inducing signalling complex,” and the following sequence of cleavage processes. In genetically modified caspase-8-deficient Jurkat cells, the apoptotic effects are only slightly reduced, whereas, in FADD-negative Jurkat cells, the TBT effect is significantly diminished. We could show that caspase-10 is recruited by the TRAIL-R2 receptor and apoptosis is totally prevented when caspase-10 is specifically inhibited in all three cell lines

Adaptation dynamics of the quasispecies model

We study the adaptation dynamics of an initially maladapted population evolving via the elementary processes of mutation and selection. The evolution occurs on rugged fitness landscapes which are defined on the multi-dimensional genotypic space and have many local peaks separated by low fitness valleys. We mainly focus on the Eigen's model that describes the deterministic dynamics of an infinite number of self-replicating molecules. In the stationary state, for small mutation rates such a population forms a {\it quasispecies} which consists of the fittest genotype and its closely related mutants. The quasispecies dynamics on rugged fitness landscape follow a punctuated (or step-like) pattern in which a population jumps from a low fitness peak to a higher one, stays there for a considerable time before shifting the peak again and eventually reaches the global maximum of the fitness landscape. We calculate exactly several properties of this dynamical process within a simplified version of the quasispecies model.Comment: Proceedings of Statphys conference at IIT Guwahati, to be published in Praman

Coarsening of Sand Ripples in Mass Transfer Models with Extinction

Coarsening of sand ripples is studied in a one-dimensional stochastic model, where neighboring ripples exchange mass with algebraic rates, $\Gamma(m) \sim m^\gamma$, and ripples of zero mass are removed from the system. For $\gamma < 0$ ripples vanish through rare fluctuations and the average ripples mass grows as \avem(t) \sim -\gamma^{-1} \ln (t). Temporal correlations decay as $t^{-1/2}$ or $t^{-2/3}$ depending on the symmetry of the mass transfer, and asymptotically the system is characterized by a product measure. The stationary ripple mass distribution is obtained exactly. For $\gamma > 0$ ripple evolution is linearly unstable, and the noise in the dynamics is irrelevant. For $\gamma = 1$ the problem is solved on the mean field level, but the mean-field theory does not adequately describe the full behavior of the coarsening. In particular, it fails to account for the numerically observed universality with respect to the initial ripple size distribution. The results are not restricted to sand ripple evolution since the model can be mapped to zero range processes, urn models, exclusion processes, and cluster-cluster aggregation.Comment: 10 pages, 8 figures, RevTeX4, submitted to Phys. Rev.

POSTURE CONTROL AFTER LONGITUDINAL ROTATIONS IN DIFFERENT DIRECTIONS

Fast rotations induce load on the human organism. Hanging vertical, young figure skaters perform rotations around the longitudinal axis. After the rotations we investigated the posture control. The differences between the direction of rotations will be explored. There were no differences between the rotations to preferred and not preferred direction of the rotations, but there were individual exceptions. Angular velocity about 500 deg/sec were reached. The results of the posture control show an effect of the rotations. But there is also no effect on the direction. The postural sway after rotation to preferred direction were not different to the postural sway after rotations to the opposite direction. Further investigations will use the results of this pilot study

Stimulation of Phospholipase A2 by Toxic Main Group Heavy Metals: Partly Dependent on G-proteins?

Organometals induce platelet aggregation and inorganic metal ions such as Cd2+ or Pb2+ sensitise human blood platelets to aggregating agents and this action is associated with the liberation of arachidonic acid and eicosanoid formation. The same mechanism is observed using human leukaemia cells (HL-60) when treated with MeHgCl or Et3PbCl. The fatty acid liberation within human platelets and HL-60 cells could only be inhibited with phospholipase A2 inhibitors of different specificity