Heterotic free fermionic and symmetric toroidal orbifold models

Free fermionic models and symmetric heterotic toroidal orbifolds both constitute exact backgrounds that can be used effectively for phenomenological explorations within string theory. Even though it is widely believed that for Z2xZ2 orbifolds the two descriptions should be equivalent, a detailed dictionary between both formulations is still lacking. This paper aims to fill this gap: We give a detailed account of how the input data of both descriptions can be related to each other. In particular, we show that the generalized GSO phases of the free fermionic model correspond to generalized torsion phases used in orbifold model building. We illustrate our translation methods by providing free fermionic realizations for all Z2xZ2 orbifold geometries in six dimensions.Comment: 1+49 pages latex, minor revisions and references adde

Using Network Analysis to Understand Knowledge Mobilization in a Community-based Organization

Background Knowledge mobilization (KM) has been described as putting research in the hands of research users. Network analysis is an empirical approach that has potential for examining the complex process of knowledge mobilization within community-based organizations (CBOs). Yet, conducting a network analysis in a CBO presents challenges. Purpose The purpose of this paper is to demonstrate the value and feasibility of using network analysis as a method for understanding knowledge mobilization within a CBO by (1) presenting challenges and solutions to conducting a network analysis in a CBO, (2) examining the feasibility of our methodology, and (3) demonstrating the utility of this methodology through an example of a network analysis conducted in a CBO engaging in knowledge mobilization activities. Method The final method used by the partnership team to conduct our network analysis of a CBO is described. Results An example of network analysis results of a CBO engaging in knowledge mobilization is presented. In total, 81 participants completed the network survey. All of the feasibility benchmarks set by the CBO were met. Results of the network analysis are highlighted and discussed as a means of identifying (1) prominent and influential individuals in the knowledge mobilization process and (2) areas for improvement in future knowledge mobilization initiatives. Conclusion Findings demonstrate that network analysis can be feasibly used to provide a rich description of a CBO engaging in knowledge mobilization activities

The application of 3D motion analysis in surgical evaluation and training; a pilot study.

Aim: To evaluate whole body, forearm, hand and surgical tool movements during various stitching tasks in experienced surgeons and final year medical students. Objectives: To determine the time required to complete each surgical task. To analyse the body centre of mass, neck, elbow, forearm and hand kinematics, the distance travelled by the surgical tool to determine the reliability, repeatability and compare differences of the aforementioned objective measures within and between surgeons and students. Method: A Cross-sectional 3D motion analysis pilot study designed. Five volunteer surgeons and five medical students were included. Retro-reflective markers were affixed to each participant’s skin on specific palpated anatomical landmarks and on a silicon suturing pad and surgical tools. Result: Experienced surgeons required significantly less time to complete each task. Their body centre of mass as well as their neck ROM were significantly smaller. The surgical tool also travelled less distance when used by surgeons (p[less than]0.05). Repeatability was higher in surgeons (ICC>0.70) compared to students (ICC>0.55). Conclusion: It is feasible to evaluate the surgical competences of junior surgeons from the very earliest years of their training. Optical Motion Capture System is a promising tool in Surgical Skills Teaching & Training

Response of the chiral soliton lattice to spin polarized currents

Spin polarized currents originate a spin-transfer torque that enables the manipulation of magnetic textures. Here we theoretically study the effect of a spin-polarized current on the magnetic texture corresponding to a chiral soliton lattice in a monoaxial helimagnet under a transverse magnetic field. At sufficiently small current density the chiral soliton lattice reaches a steady motion state with a velocity proportional to the intensity of the applied current, the mobility being independent of the density of solitons and the magnetic field. This motion is accompanied with a small conical distortion of the chiral soliton lattice. At large current density the spin-transfer torque destabilizes the chiral soliton lattice, driving the system to a ferromagnetic state parallel to the magnetic field. We analyze how the deformation of the chiral soliton lattice depends on the applied current density. The destruction of the chiral soliton lattice under current could serve as a possible erasure mechanisms for spintronic applications.Comment: 13 pages, 8 figure

The psychological reality of spatio-temporal metaphors

Time provides essential structure to human experience. In this chapter we review the available empirical evidence for a fundamental metaphoric structure such as TIME IS SPACE in figurative language and thought. The chapter is organized into three over-arching themes: Motion through time, that is, the influence of ego-moving metaphors (motion of the observer’s context along a timeline) and time-moving metaphors (motion of events along a timeline) on the construal of time as moving or stationary; Temporal succession, and how it is conceptualized on the specific spatial axes (horizontal and/or vertical) used to sequence events in time; and lastly, temporal duration, focusing on the metaphors used to describe the temporal extension of an event and their influence on the perception of duration. A large part of the experimental evidence lends support to the psychological reality of the TIME IS SPACE metaphor, revealing the inextricable link between conceptual metaphor in language and fundamental thinking processes like perception of temporal succession and time estimation, contributing to the emerging broader picture of the powerful role of linguistic experience in shaping the way conceptual representations are formed and activated. At the same time, the review also reveals that linguistic space-time mappings may be overridden by cultural conventions. Taken together, the evidence available to date suggests that the mental representation of time in humans is the outcome of an intricate interplay between linguistic (i.e. metaphors) and cultural factors, calling for further exploration of this interplay through empirical research

Illuminating ATOM: Taking time across the colour category border

Walsh’s A Theory Of Magnitude (ATOM) contends that we represent magnitudes such as number, space, time and luminance on a shared metric, such that ‘more’ of one leads to the perception of ‘more’ of the other (e.g. Walsh, 2003). In support of ATOM, participants have been shown to judge intervals between stimuli that are more discrepant in luminance as having a longer duration than intervals between stimuli whose luminance differs by a smaller degree (Xuan, Zhang, He, & Chen, 2007). We tested the potential limits to the ability of luminance to influence duration perception by investigating the possibility that the luminance-duration relationship might be interrupted by a concurrent change in the colour of that luminance. We showed native Greek and native English speakers sequences of stimuli that could be either light or dark versions of green or blue. Whereas for both groups a shift in green luminance does not comprise a categorical shift in colour, for Greek speakers shifts between light and dark blue cross a colour category boundary (ghalazio and ble respectively). We found that duration judgements were neither interrupted nor inflated by a shift in colour category. These results represent the first evidence that the influence of luminance change on duration perception is resistant to interference from discrete changes within the same perceptual input