Unzipping an adsorbed polymer in a dirty or random environment

The phase diagram of unzipping of an adsorbed directed polymer in two dimensions in a random medium has been determined. Both the hard-wall and the soft-wall cases are considered. Exact solutions for the pure problem with different affinities on the two sides are given. The results obtained by the numerical procedure adopted here are shown to agree with the exact results for the pure case. The characteristic exponents for unzipping for the random problem are different from the pure case. The distribution functions for the unzipped length, first bubble, and the spacer are determined.Comment: Published version, uses revtex4, 14 page

Complete Phase Diagram of DNA Unzipping: Eye, Y-fork and triple point

We study the unzipping of double stranded DNA (dsDNA) by applying a pulling force at a fraction $s$ $(0 \le s \le 1)$ from the anchored end. From exact analytical and numerical results, the complete phase diagram is presented. The phase diagram shows a strong ensemble dependence for various values of $s$. In addition, we show the existence of an ``eye'' phase and a triple point.Comment: 4 pages, 4 figures; revised version: misprints corrected. References corrected/added. To appear in Physical Review Letter

Multiparticle Schrodinger operators with point interactions in the plane

We study a system of N bosons in the plane interacting with delta function potentials. After a coupling constant renormalization we show that the Hamiltonian defines a self-adjoint operator and obtain a lower bound for the energy. The same results hold if one includes a regular inter-particle potential.Comment: 17 pages, Late

A Theory of Errors in Quantum Measurement

It is common to model random errors in a classical measurement by the normal (Gaussian) distribution, because of the central limit theorem. In the quantum theory, the analogous hypothesis is that the matrix elements of the error in an observable are distributed normally. We obtain the probability distribution this implies for the outcome of a measurement, exactly for the case of 2x2 matrices and in the steepest descent approximation in general. Due to the phenomenon of `level repulsion', the probability distributions obtained are quite different from the Gaussian.Comment: Based on talk at "Spacetime and Fundamental Interactions: Quantum Aspects" A conference to honor A. P. Balachandran's 65th Birthda

Enhancement of Heat Transfer in Shell and Tube Heat Exchanger using Different Porous Medium: A CFD-based Study

The present study is to investigate the heat transfer enhancement in a cylindrical heat exchanger using porous media. The heat exchanger is modelled by a cylindrical cavity (Shell) with inlet and outlet thermally insulated ports and five tubes which contain hot water and cold water flows in shell. The effect of porosity on heat transfer enhancement is studied at different mass flow rate 0.15, 0.2, 0.25 and 0.30 Kg/sec. The study about effect of porosity on heat transfer enhancement is done by both experimentally and CFD based and the results are compared with simple heat exchanger. In present study, two different types of porous materials are used and Porosity is taken as 80%. The effect of varying mass flow rate on outlet temperature, heat transfer coefficient, Reynolds number and Nusselt number has been investigated

Membership Questions for Timed and Hybrid Automata

Timed and hybrid automata are extensions of finite-state machines for formal modeling of embedded systems with both discrete and continuous components. Reachability problems for these automata are well studied and have been implemented in verification tools. In this paper, for the purpose of effective error reporting and testing, we consider the membership problems for such automata. We consider different types of membership problems depending on whether the path (i.e. edge-sequence), or the trace (i.e. event-sequence), or the timed trace (i.e. timestamped event-sequence), is specified. We give comprehensive results regarding the complexity of these membership questions for different types of automata, such as timed automata and linear hybrid automata, with and without ε-transitions. In particular, we give an efficient O (n.m2) algorithm for generating timestamps corresponding a path of length n in a timed automaton with m clocks. This algorithm is implemented in the verifier COSPAN to improve its diagnostic feedback during timing verification. Second, we show that for automata without ε-transitions, the membership question is NP-complete for different types of automata whether or not the timestamps are specified along with the trace. Third, we show that for automata with ε-transitions, the membership question is as hard as the reachability question even for timed traces: it is PSPACE-complete for timed automata, and undecidable for slight generalizations

Manipulating a single adsorbed DNA for a critical endpoint

We show the existence of a critical endpoint in the phase diagram of unzipping of an adsorbed double-stranded (ds) polymer like DNA. The competition of base pairing, adsorption and stretching by an external force leads to the critical end point. From exact results, the location of the critical end point is determined and its classical nature established.Comment: 6 pages, 5 figures, Published versio

A Non-Riemannian Metric on Space-Time Emergent From Scalar Quantum Field Theory

We show that the two-point function \sigma(x,x')=\sqrt{} of a scalar quantum field theory is a metric (i.e., a symmetric positive function satisfying the triangle inequality) on space-time (with imaginary time). It is very different from the Euclidean metric |x-x'| at large distances, yet agrees with it at short distances. For example, space-time has finite diameter which is not universal. The Lipschitz equivalence class of the metric is independent of the cutoff. \sigma(x,x') is not the length of the geodesic in any Riemannian metric. Nevertheless, it is possible to embed space-time in a higher dimensional space so that \sigma(x,x') is the length of the geodesic in the ambient space. \sigma(x,x') should be useful in constructing the continuum limit of quantum field theory with fundamental scalar particles

Values, Susceptibility to Normative Influence, and Attribute Importance Weights: A Nomological Analysis

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141583/1/jcpy115.pd