Coordinates with Non-Singular Curvature for a Time Dependent Black Hole Horizon

A naive introduction of a dependency of the mass of a black hole on the Schwarzschild time coordinate results in singular behavior of curvature invariants at the horizon, violating expectations from complementarity. If instead a temporal dependence is introduced in terms of a coordinate akin to the river time representation, the Ricci scalar is nowhere singular away from the origin. It is found that for a shrinking mass scale due to evaporation, the null radial geodesics that generate the horizon are slightly displaced from the coordinate singularity. In addition, a changing horizon scale significantly alters the form of the coordinate singularity in diagonal (orthogonal) metric coordinates representing the space-time. A Penrose diagram describing the growth and evaporation of an example black hole is constructed to examine the evolution of the coordinate singularity.Comment: 15 pages, 1 figure, additional citation

Modes of Distinction: Home and Avant Garde Modalities

Study of the relationships between home movies, amateur filmmaking and avant-garde cinema. Published in Spanish in Cuevas, Efrén (ed.), "La casa abierta. El cine doméstico y sus reciclajes contemporáneos", pp. 273-299

Aspects of brane-antibrane inflation

I describe a dynamical mechanism for solving the fine-tuning problem of brane-antibrane inflation. By inflating with stacks of branes and antibranes, the branes can naturally be trapped at a metastable minimum of the potential. As branes tunnel out of this minimum, the shape of the potential changes to make the minimum shallower. Eventually the minimum disappears and the remaining branes roll slowly because the potential is nearly flat. I show that even with a small number of branes, there is a good chance of getting enough inflation. Running of the spectral index is correlated with the tilt in such a way as to provide a test of the model by future CMB experiments.Comment: 6 pages, 5 figures; proceedings of Theory Canada 1 conference, 2-5 June 2005, UBC, Vancouve

Incompatible sets of gradients and metastability

We give a mathematical analysis of a concept of metastability induced by incompatibility. The physical setting is a single parent phase, just about to undergo transformation to a product phase of lower energy density. Under certain conditions of incompatibility of the energy wells of this energy density, we show that the parent phase is metastable in a strong sense, namely it is a local minimizer of the free energy in an $L^1$ neighbourhood of its deformation. The reason behind this result is that, due to the incompatibility of the energy wells, a small nucleus of the product phase is necessarily accompanied by a stressed transition layer whose energetic cost exceeds the energy lowering capacity of the nucleus. We define and characterize incompatible sets of matrices, in terms of which the transition layer estimate at the heart of the proof of metastability is expressed. Finally we discuss connections with experiment and place this concept of metastability in the wider context of recent theoretical and experimental research on metastability and hysteresis.Comment: Archive for Rational Mechanics and Analysis, to appea

INNOVATION THROUGH (INTERNATIONAL) FOOD SUPPLY CHAIN DEVELOPMENT: A RESEARCH AGENDA

This paper presents a research agenda on innovation through (international) food supply chains and networks in developing countries. It derives major topics from a multi-perspective view on international food chains (economic, technology, social/legal and environment) and from different theoretical streams dealing with chains and networks (Supply Chain Management, Industrial Organization theory and Network Theory). Three agri-supply chain projects in developing countries (Thailand, South-Africa, Ghana) are analyzed to identify focus areas in supply chain development projects and important gaps. These projects were collaborative actions between companies and research institutes to initiate international supply chain development.Industrial Organization,

Ex-ante Evaluation of Cassava Research for Development in Malawi: A Farm Household and Random Utility Modeling Approach

Ex ante evaluation of agricultural research for development projects has become important in recent years for priority setting, ex post impact assessment and learning about generalizability to other populations and contexts. We apply farm household and random utility modeling to baseline survey data and evaluate the impact of a cassava research for development project in Malawi prior to its implementation. The project is being implemented to unlock the potential of cassava in response to the global food crisis. We find that a high proportion of farm households are not self-sufficient in food production and can be assisted by increasing the productivity of land and labor in production, processing and marketing of cassava to reduce deficits and increase marketed surplus. The research for development embeds research in an innovation systems network and speeds up exposure, awareness, adoption and diffusion. This increases the likelihood that incremental benefits will be generated and accrue earlier compared to the counterfactual without the project.Resource /Energy Economics and Policy,

Market segmentation in behavioral perspective

A segmentation approach is presented using both traditional demographic segmentation bases (age, social class/occupation, and working status) and a segmentation by benefits sought. The benefits sought in this case are utilitarian and informational reinforcement, variables developed from the Behavioral Perspective Model (BPM). Using data from 1,847 consumers and from a total of 76,682 individual purchases, brand choice and price and reinforcement responsiveness were assessed for each segment across the UK cookie (biscuits) market. Building on previous work, the results suggest that the segmentation of brand choice using benefits sought is useful. This is especially the case alongside demographic variables. This article provides a theoretical and practical segmentation approach to both the behavioral psychology literature and the wider marketing segmentation literature

The quadratic spinor Lagrangian is equivalent to the teleparallel theory

The quadratic spinor Lagrangian is shown to be equivalent to the teleparallel / tetrad representation of Einstein's theory. An important consequence is that the energy-momentum density obtained from this quadratic spinor Lagrangian is essentially the same as the ``tensor'' proposed by Moller in 1961.Comment: 10 pages, RevTe

Interpersonal behavior in anticipation of pain:a naturalistic study of behavioral mimicry prior to surgery

Abstract. Introduction:. Social relationships facilitate coping with pain, but research suggests that it may be difficult to galvanize social support during an episode of acute pain. Objectives:. The current research examined whether social connections are optimized in the anticipation of pain by observing patients' mimicry of an interaction partner prior to surgery. We hypothesized that when controlling for their current experience of pain, patients' anticipation of pain would be associated with greater mimicry of an interaction partner. Methods:. Sixty-five patients were interviewed in the waiting room of a maxillofacial surgery unit prior to the removal of an impacted wisdom tooth. Patients' spontaneous mimicry of an interviewer was observed. Patients then rated the quality and intensity of their anticipated pain, as well as the intensity of their current pain and their affective distress. Results:. Anticipated pain, current pain, and affective distress were positively correlated. Current pain was associated with less frequent mimicry of an interaction partner. The zero-order correlation between anticipated pain and mimicry did not reach conventional levels of significance; however, when controlling for current pain, anticipated pain predicted more frequent mimicry of an interaction partner. The relationship between anticipated pain and mimicry was not explained by affective distress. Conclusion:. This is the first study to demonstrate that anticipated and current pain relate to behavioral mimicry in divergent ways. Further research is needed to investigate whether the current pattern of results generalizes to other interpersonal behaviors that facilitate social bonds