Reunion of random walkers with a long range interaction: applications to polymers and quantum mechanics

We use renormalization group to calculate the reunion and survival exponents of a set of random walkers interacting with a long range $1/r^2$ and a short range interaction. These exponents are used to study the binding-unbinding transition of polymers and the behavior of several quantum problems.Comment: Revtex 3.1, 9 pages (two-column format), 3 figures. Published version (PRE 63, 051103 (2001)). Reference corrections incorporated (PRE 64, 059902 (2001) (E

Delayed financial disclosure: Mexico's recent experience

This article documents a delay in the public release of Mexican international reserve data in the months before Mexico's debt crisis at the end of 1994. The article establishes that in that year investors did not know the level of Mexican reserves before October; yet this lack of information did not seem to reduce investor confidence in the Mexican economy. The article does not establish whether the delay in releasing reserve data was due to logistical problems or to a government strategy. The possibility that the delay was strategic is evaluated by developing an economic model that captures some of the principal constraints facing the Mexican government in 1994 and that makes explicit the conflicting objectives of the government and investors. The model shows that in such an environment with private information, strategic delay can occur in equilibrium if investors are uncertain about the cause of the delay.Mexico ; Devaluation of currency ; Peso, Mexican

Boundary Dynamics in Dilaton Gravity

We study the dynamics of the boundary dilaton gravity coupled to N massles scalars. We rederive the boundary conditions of [1] and [3] in a way which makes the requirement of reparametrization invariance and role of conformal anomaly explicit. We then study the semiclassical behaviour of the boundary in the N = 24 theory in the presence of an incoming matter wave with a constant energy flux spreaded over a finite interval. There is a critical value of the matter energy density below which the boundary is stable and all the matter is reflected back. For energy densities greater than this critical value there is a similar behaviour for small values of total energy thrown in. However, when the total energy exceeds another critical value, the boundary exibits a runaway behaviour and the spacetime devolopes singularities and horizons.Comment: 16 pages, Latex file, TIFR/TH/94-24, IC/94/147 (preprint numbers are included

Multi-shocks in asymmetric simple exclusions processes: Insights from fixed-point analysis of the boundary-layers

The boundary-induced phase transitions in an asymmetric simple exclusion process with inter-particle repulsion and bulk non-conservation are analyzed through the fixed points of the boundary layers. This system is known to have phases in which particle density profiles have different kinds of shocks. We show how this boundary-layer fixed-point method allows us to gain physical insights on the nature of the phases and also to obtain several quantitative results on the density profiles especially on the nature of the boundary-layers and shocks.Comment: 12 pages, 8 figure

Phase-plane analysis of driven multi-lane exclusion models

We show how a fixed point based boundary-layer analysis technique can be used to obtain the steady-state particle density profiles of driven exclusion processes on two-lane systems with open boundaries. We have considered two distinct two-lane systems. In the first, particles hop on the lanes in one direction obeying exclusion principle and there is no exchange of particles between the lanes. The hopping on one lane is affected by the particle occupancies on the other, which thereby introduces an indirect interaction among the lanes. Through a phase plane analysis of the boundary layer equation, we show why the bulk density undergoes a sharp change as the interaction between the lanes is increased. The second system involves one lane with driven exclusion process and the other with biased diffusion of particles. In contrast to the previous model, here there is a direct interaction between the lanes due to particle exchange between them. In this model, we have looked at two possible scenarios with constant (flat) and non-constant bulk profiles. The fixed point based boundary layer method provides a new perspective on several aspects including those related to maximal/minimal current phases, possibilities of shocks under very restricted boundary conditions for the flat profile but over a wide range of boundary conditions for the non-constant profile.Comment: 13 pages, 17 figure

A dynamically extending exclusion process

An extension of the totally asymmetric exclusion process, which incorporates a dynamically extending lattice is explored. Although originally inspired as a model for filamentous fungal growth, here the dynamically extending exclusion process (DEEP) is studied in its own right, as a nontrivial addition to the class of nonequilibrium exclusion process models. Here we discuss various mean-field approximation schemes and elucidate the steady state behaviour of the model and its associated phase diagram. Of particular note is that the dynamics of the extending lattice leads to a new region in the phase diagram in which a shock discontinuity in the density travels forward with a velocity that is lower than the velocity of the tip of the lattice. Thus in this region the shock recedes from both boundaries.Comment: 20 pages, 12 figure

A Perspective on Zinc Oxide Based Diluted Magnetic Semiconductors

Diluted magnetic semiconductor (DMS) is envisaged to portray a substantial position in inter-punitive material science and prospect spintronics. The reason being spin and charge degrees of freedom are accommodated into solitary matter and their interaction is anticipated to probe innovative electronic devices. DMSs evince multifarious advantages such as wide band gap apposite for applications with short wavelength light, transparency and dye ability with pigments, high carrier concentration, capability to be cultivated even on plastic substrate at low temperature, green safety, durability , most importantly economical. Various theoretical and experimental research findings have been proposed on the ferromagnetic, paramagnetic, antiferromagnetic and spin glass properties at room-temperature of transition metal-doped DMSs such as TiO2, ZnO, Cu2O, SnO2, In2O3 etc in last few years. The objective of the paper is to comprehend the recent research advancement of ZnO based DMS specimens doped with various 3d transition metals

The international training and research program on groundwater governance in Asia: Theory and practice

CGIAR-CPWF Project “International Training and Research Program on Groundwater Governance in Asia: Theory and Practice” was designed and implemented by International Water Management Institute (IWMI) to address the deficiencies in human capacity of managing groundwater in the two large basins of the world- the Indus-Gangetic basin and the Yellow River basin. The basic premise of the project was that proper groundwater management needs to be built on informed knowledge of professionals from the region, with emphasis on inter-disciplinary knowledge and understanding of the actual groundwater situation in the rural areas. This objective was achieved through development of an international courseware on the subject and actual enhancement of the capacity of existing institutions and about 80 professionals working at junior and senior levels and engaged in media dissemination in the basin states involved in groundwater research and management so that they could undertake more integrated, multi-disciplinary and sustainable approaches to groundwater governance

Duality and phase diagram of one dimensional transport

The observation of duality by Mukherji and Mishra in one dimensional transport problems has been used to develop a general approach to classify and characterize the steady state phase diagrams. The phase diagrams are determined by the zeros of a set of coarse-grained functions without the need of detailed knowledge of microscopic dynamics. In the process, a new class of nonequilibrium multicritical points has been identified.Comment: 6 pages, 2 figures (4 eps files