Scalar Quantum Field Theory on Fractals

We construct a family of measures for random fields based on the iterated subdivision of simple geometric shapes (triangles, squares, tetrahedrons) into a finite number of similar shapes. The intent is to construct continuum limits of scale invariant scalar field theories, by imitating Wiener's construction of the measure on the space of functions of one variable. These are Gaussian measures, except for one example of a non-Gaussian fixed point for the Ising model on a fractal. In the continuum limits what we construct have correlation functions that vary as a power of distance. In most cases this is a positive power (as for the Wiener measure) but we also find a few examples with negative exponent. In all cases the exponent is an irrational number, which depends on the particular subdivision scheme used. This suggests that the continuum limits corresponds to quantum field theories (random fields) on spaces of fractional dimension

Black Hole Geometries in Noncommutative String Theory

We obtain a generalized Schwarzschild (GS-) and a generalized Reissner-Nordstrom (GRN-) black hole geometries in (3+1)-dimensions, in a noncommutative string theory. In particular, we consider an effective theory of gravity on a curved $D_3$-brane in presence of an electromagnetic (EM-) field. Two different length scales, inherent in its noncommutative counter-part, are exploited to obtain a theory of effective gravity coupled to an U(1) noncommutative gauge theory to all orders in $\Theta$. It is shown that the GRN-black hole geometry, in the Planckian regime, reduces to the GS-black hole. However in the classical regime it may be seen to govern both Reissner-Nordstrom and Schwarzschild geometries independently. The emerging notion of 2D black holes evident in the frame-work are analyzed. It is argued that the $D$-string in the theory may be described by the near horizon 2D black hole geometry, in the gravity decoupling limit. Finally, our analysis explains the nature of the effective force derived from the nonlinear EM-field and accounts for the Hawking radiation phenomenon in the formalism.Comment: 30 pages, 2 figure

The Generalised Raychaudhuri Equations : Examples

Specific examples of the generalized Raychaudhuri Equations for the evolution of deformations along families of $D$ dimensional surfaces embedded in a background $N$ dimensional spacetime are discussed. These include string worldsheets embedded in four dimensional spacetimes and two dimensional timelike hypersurfaces in a three dimensional curved background. The issue of focussing of families of surfaces is introduced and analysed in some detail.Comment: 8 pages (Revtex, Twocolumn format). Corrected(see section on string worldsheets), reorganised and shortened slightl

Knowledge, Attitude and Practice of Cervical Cancer Screening Through Visual Inspection with Acetic Acid

Detection of the cervical cancer requires practice of screening that will increase survival rates from the disease. Visual Inspection with Acetic Acid (VIA) is an alternative to screening for cervical cancer.This study aims to assess the knowledge, attitude, and practice towards VIA screening among adult women. We used a cross-sectional study in urban areas of Bangladesh with a sample of 285 respondents those were interviewed through semi-structured questionnaire. Analyses have done by targeting the objectives and considering the indicators with appropriate test statsitsics.About 56.1% respondents aged between 18 and 35 years with majority had at least secondary education including 29.5% were from affluent group. Though the highest majority of women had the knowledge of cervical cancer but only quarter was aware of VIA. A few of the respondents adopted any screening test for detecting cervical cancer and this lower coverage could be due to, among other reasons, lack of knowledge, accessibility, and service availability. The results also indicated that higher educational level of respondents is the predictor of improving knowledge on the disease and early adoption of available test procedure.An awareness building program should be designed for women of early detection of cervical cancer using VIA procedure

Localized reversible nanoscale phase separation in Pr_0.63Ca_0.37MnO_3 single crystal using a scanning tunneling microscope tip

We report the destabilization of the charge ordered insulating (COI) state in a localized region of Pr_0.63Ca_0.37MnO_3 single crystal by current injection using a scanning tunneling microscope tip. This leads to controlled phase separation and formation of localized metallic nanoislands in the COI matrix which have been detected by local tunneling conductance mapping. The metallic regions thus created persist even after reducing the injected current to lower values. The original conductance state can be restored by injecting a current of similar magnitude but of opposite polarity. We thus achieve reversible nanoscale phase separation that gives rise to the possibility to "write, read, and erase" nanosized conducting regions in an insulating matrix with high spatial resolution.Comment: 8 pages, 4 figures, Appl. Phys. Lett (accepted for publication

An Algorithm to Generate Classical Solutions for String Effective Action

It is shown explicitly, that a number of solutions for the background field equations of the string effective action in space-time dimension D can be generated from any known lower dimensional solution, when background fields have only time dependence. An application of the result to the two dimensional charged black hole is presented. The case of background with more general coordinate dependence is also discussed.Comment: 12 page