Pseudo-electromagnetic fields in topological semimetals

Dirac and Weyl semimetals, materials where electrons behave as relativistic fermions, react to position- and time-dependent perturbations, such as strain, as if emergent electromagnetic fields were applied. Since they differ from external electromagnetic fields in their symmetries and phenomenology they are called pseudo-electromagnetic fields, and enable a simple and unified description of a variety of inhomogeneous systems involving topological semimetals. We review the different physical ways to create effective pseudo-fields, their observable consequences as well as their similarities and differences compared to electromagnetic fields. Among these difference is their effect on quantum anomalies, the absence of a classical symmetry in the quantum theory, which we revisit from a quantum field theory and a semiclassical viewpoint. We conclude with predicted observable signatures of the pseudo-fields and the nascent experimental status.Comment: 18 pages, 6 (preliminary) figures. Original submitted version, comments welcom

Interference, Coulomb blockade, and the identification of non-abelian quantum Hall states

We examine the relation between different electronic transport phenomena in a Fabry-Perot interferometer in the fractional quantum Hall regime. In particular, we study the way these phenomena reflect the statistics of quantum Hall quasi-particles. For two series of states we examine, one abelian and one non-abelian, we show that the information that may be obtained from measurements of the lowest order interference pattern in an open Fabry-Perot interferometer is identical to the one that may be obtained from the temperature dependence of Coulomb blockade peaks in a closed interferometer. We argue that despite the similarity between the experimental signatures of the two series of states, interference and Coulomb blockade measurements are likely to be able to distinguish between abelian and non-abelian states, due to the sensitivity of the abelian states to local perturbations, to which the non-abelian states are insensitive.Comment: 10 pages. Published versio

State-space based mass event-history model I: many decision-making agents with one target

A dynamic decision-making system that includes a mass of indistinguishable agents could manifest impressive heterogeneity. This kind of nonhomogeneity is postulated to result from macroscopic behavioral tactics employed by almost all involved agents. A State-Space Based (SSB) mass event-history model is developed here to explore the potential existence of such macroscopic behaviors. By imposing an unobserved internal state-space variable into the system, each individual's event-history is made into a composition of a common state duration and an individual specific time to action. With the common state modeling of the macroscopic behavior, parametric statistical inferences are derived under the current-status data structure and conditional independence assumptions. Identifiability and computation related problems are also addressed. From the dynamic perspectives of system-wise heterogeneity, this SSB mass event-history model is shown to be very distinct from a random effect model via the Principle Component Analysis (PCA) in a numerical experiment. Real data showing the mass invasion by two species of parasitic nematode into two species of host larvae are also analyzed. The analysis results not only are found coherent in the context of the biology of the nematode as a parasite, but also include new quantitative interpretations.Comment: Published in at http://dx.doi.org/10.1214/08-AOAS189 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

East, west, would home really be best? On dissatisfaction with offshore-outsourcing and firms' inclination to backsource

With so many firms seemingly disenchanted with their experiences of offshore outsourcing one may well wonder why relatively few of these firms choose to ‘backsource’ – i.e., bring their offshored operations back in-house. Of all sourcing decisions that firms take, backsourcing is perhaps the least understood and least researched. In this article we draw on the behavioral theory of the firm (BTF) to propose a new model in which differences in firms' inclination to backsource are ascribed to the level of dissatisfaction at not having achieved offshoring aspirations. Building on BTF concepts of bounded rationality, problemistic search and satisficing decisions, the model suggests that how this dissatisfaction with offshoring affects a firm's inclination to backsource is dependent on managerial expectations regarding the technical challenges of reintegrating activities and the possible financial losses and decline in quality following backsourcing, as well as on internal political support and financial slack for backsourcing. SEM analysis of data from U.S. and U.K. firms shows support for the model. The study highlights the importance of recognizing the role of managerial perceptions and biases and subgroup political relations in shaping firms' backsourcing behaviors. We also discuss the study's contributions to research and practice

Telling donor-conceived children about their conception: Evaluation of the use of the Donor Conception Network children's books

If parents have used donated gametes, it is a personal choice whether they disclose to their children. For those that do, there is, however, little advice on how to tell their children. The Donor Conception Network (DCN) has made a series of books to help parents disclose. This study evaluated parents’ experience of using these books. An online survey with both quantitative and qualitative questions was used. The DCN membership and social media were used to publicize the survey, and 108 responses were analysed. At the time of conception, the parents’ family types were mainly mother and father (56.5%) and solo mothers (36.1%). The method of conception was mainly donor spermatozoa (55.6%) followed by donor egg (38.0%), double donation (8.3%) and one case of surrogacy. Most parents had read the book to their children before 2 years of age (76.9%). Before reading the books, some of the parents had some confidence in telling (43.5%) or were very confident in telling (30.6%). After reading the books, 60.2% reported having much more confidence in telling. Most parents felt their children had no understanding (76.8%) or only some understanding (22.3%) of donor conception before reading the books. After reading the books most parents felt their children's understanding had increased (71.3%). Most parents felt that reading the books had given them more confidence in using donor conception language (90.7%). The use of books to tell children about their conception may be a useful resource for parents wishing to be open with their children

Addressing disaster and health risks for sustainable outer space

publishedVersio

Organizing The Innovation System For Reusability: The Case Of Made-To-Order Markets

This paper examines the transfer of designs between projects within firm in the context of made-to-order producing companies. This practice is also known as knowledge reuse. Past studies has provided a detailed account of the strategies and processes involved in the reuse of technologies. Nonetheless, a large portion of this research was based on evidence collected in mass-producing companies. This paper attempts to develop a complementary framework to identify the strategies involved in reusing technologies in the made-to-order context. Data were drawn from three aerospace companies based in Israel. Two strategies emerged from the empirical evidence: exploit product success and design for reuse