The Problem of Time and Quantum Black Holes

We discuss the derivation of the so-called semi-classical equations for both mini-superspace and dilaton gravity. We find that there is no systematic derivation of a semi-classical theory in which quantum mechanics is formulated in a space-time that is a solution of Einstein's equation, with the expectation value of the matter stress tensor on the right-hand side. The issues involved are related to the well-known problems associated with the interpretation of the Wheeler-deWitt equation in quantum gravity, including the problem of time. We explore the de Broglie-Bohm interpretation of quantum mechanics (and field theory) as a way of spontaneously breaking general covariance, and thereby giving meaning to the equations that many authors have been using to analyze black hole evaporation. We comment on the implications for the ``information loss" problem.Comment: 30 pages, COLO-HEP-33

Determinants of Translating Entrepreneurial Intention to Action: A Study of Undergraduate Students of the University of Peradeniya, Sri Lanka

Entrepreneurs are the wealth creators of an economy, and hence business start-ups are always encouraged. Although it is often suggested that entrepreneurial intentions are strong predictors of entrepreneurial action, all intentions do not necessarily translate into action as there is an “intention-action gap” when nascent entrepreneurs fail to act on their intentions. This study aimed to explain the gap between entrepreneurial intentions and entrepreneurial action and identify the determinants of the intention to action translation by surveying the final year undergraduates from different degree programs at a major public university in Sri Lanka. The research focused on the effects of demographic, psychographic, and environmental factors to explain the intention-action gap. Data were collected using a pre-tested self-administered questionnaire. The questionnaire was circulated online among the entire final year undergraduate student population of the University of Peradeniya. Four hundred and fifty-three undergraduate students (n=453) responded to the survey. Hierarchical OLS regression with the main effect model and an interactions model was used for the data analysis. Results found that of the respondents who had entrepreneurial intentions, 32% had taken some actions towards starting a business. The results also revealed a positive relationship between entrepreneurial intention and action and there were positive effects of gender, perceived competence in entrepreneurial skills, entrepreneurial environment in the faculty, and entrepreneurial education on entrepreneurial actions. Furthermore, it was found that progressing from entrepreneurial intention to action was more robust for male undergraduates compared to female undergraduates. Therefore, to promote entrepreneurship, introducing entrepreneurship courses, introducing programmes to improve entrepreneurial skills and competencies and promoting an entrepreneurial culture in the Faculties could be recommended. Keywords: Entrepreneurial intention, Entrepreneurial action, Hierarchical OLS regression, Student

Storage life of silverbelly (Leiognathus sp.) with delayed icing

Silver belly (leiognathus splendens) caught in September spoiled faster than the fish caught in May. This could be due to seasonal changes. For silver belly, Total Volatile Base (TVB) value could be used as a measure of spoilage. At the beginning of spoilage TVB value is between 30-40 mg. N/100g sample. The main spoilage for silver belly appears to start between 6 and 8 hours (at 28° C-30°C) after landing on board. Therefore it is not necessary to ice silverbelly immediately; it seems to be sufficient if icing can be done within 6 hours of landing on board

Thermodynamics and area in Minkowski space: Heat capacity of entanglement

Tracing over the degrees of freedom inside (or outside) a sub-volume V of Minkowski space in a given quantum state |psi>, results in a statistical ensemble described by a density matrix rho. This enables one to relate quantum fluctuations in V when in the state |psi>, to statistical fluctuations in the ensemble described by rho. These fluctuations scale linearly with the surface area of V. If V is half of space, then rho is the density matrix of a canonical ensemble in Rindler space. This enables us to `derive' area scaling of thermodynamic quantities in Rindler space from area scaling of quantum fluctuations in half of Minkowski space. When considering shapes other than half of Minkowski space, even though area scaling persists, rho does not have an interpretation as a density matrix of a canonical ensemble in a curved, or geometrically non-trivial, background.Comment: 17 page

Black Hole Formation by Sine-Gordon Solitons in Two-dimensional Dilaton Gravity

The CGHS model of two-dimensional dilaton gravity coupled to a sine-Gordon matter field is considered. The theory is exactly solvable classically, and the solutions of a kink and two-kink type solitons are studied in connection with black hole formation.Comment: 11 pages, no figures, revte

Low Cost Ultrasonic Based Wide Detection Range Smart Walking Stick for Visually Impaired

Blindness is a medical condition that requires approaching life in different ways. Unfortunately blindness still lacks proper care in the world. Many investigations have been carried out to facilitate the self-sufficient movements for the blind. The basic elementary instrument used is the traditional white cane. Many electronic travel aids have been introduced to the global market. However, more consideration is required for drawbacks of high cost, less user friendliness and less accuracy in these electronic travelling aids. Overcoming the challenges for visually impaired victims this article proposes a low cost ultrasonic based smart blind walking stick. This is a technological upgrade to the traditional white cane normally used by the blind. This device assists the victims to walk more confidently and independently. Most of the visually impaired belong to the low income community. Hence the main consideration was developing this device with Low cost and best achievable performance. This design for the visually impaired is integrated with a water sensor and ultrasonic obstacle detection sensors. The different obstacle conditions namely; mud puddles, low lying objects, ascending stairs, descending stairs and head high obstacles can be effectively and accurately detected. Early warning of danger is conveyed to the user due to the feature of wide obstacle detection range. The user is alerted by unique fingertip vibrations and sound patterns corresponding to the relevant user alert. The innovative design of the stick enables more compatibility and a wider obstacle detection range for the device with high accuracy. The low cost achievement of this design is outstanding with a total cost of less than 30 US dollars which can be further reduced in mass production. KEYWORDS: Electronic travelling aid , low cost, ultrasonic sensing , obstacle detection , vibration alert

Quantum Gravity and Turning Points in the Semiclassical Approximation

The wavefunctional in quantum gravity gives an amplitude for 3-geometries and matter fields. The four-space is usually recovered in a semiclassical approximation where the gravity variables are taken to oscillate rapidly compared to matter variables; this recovers the Schrodinger evolution for the matter. We examine turning points in the gravity variables where this approximation appears to be troublesome. We investigate the effect of such a turning point on the matter wavefunction, in simple quantum mechanical models and in a closed minisuperspace cosmology. We find that after evolving sufficiently far from the turning point the matter wavefunction recovers to a form close to that predicted by the semiclassical approximation, and we compute the leading correction (from `backreaction') in a simple model. We also show how turning points can appear in the gravitational sector in dilaton gravity. We give some remarks on the behavior of the wavefunctional in the vicinity of turning points in the context of dilaton gravity black holes.Comment: 32 pages, 3 Postscript figures, uses epsf.tex and fps.sty, some discussion, references and Acknowledgements added, version to appear in Phys. Rev.

Evaporating Black Holes and Entropy

We study the Hawking radiation for the geometry of an evaporating 1+1 dimensional black hole. We compute Bogoliubov coefficients and the stress tensor. We use a recent result of Srednicki to estimate the entropy of entanglement produced in the evaporation process, for the 1+1 dimensional hole and for the 3+1 dimensional hole. It is found that the one space dimensional result of Srednicki is the pertinent one to use, in both cases.Comment: 29 pages, one figure (available from authors), Latex. (Mailer errors removed.

Quantum Black Holes in Two Dimensions

We show that a whole class of quantum actions for dilaton-gravity, which reduce to the CGHS theory in the classical limit, can be written as a Liouville-like theory. In a sub-class of this, the field space singularity observed by several authors is absent, regardless of the number of matter fields, and in addition it is such that the dilaton-gravity functional integration range (the real line) transforms into itself for the Liouville theory fields. We also discuss some problems associated with the usual calculation of Hawking radiation, which stem from the neglect of back reaction. We give an alternative argument incorporating back reaction but find that the rate is still asymptotically constant. The latter is due to the fact that the quantum theory does not seem to have a lower bound in energy and Hawking radiation takes positive Bondi (or ADM) mass solutions to arbitrarily large negative mass.Comment: 28 pages, phyzzx, revised discussion of Hawking radiatio