2,108 research outputs found

    Students as co-creators of teaching approaches, course design and curricula: implications for academic developers

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    Within higher education, students’ voices are frequently overlooked in the design of teaching approaches, courses and curricula. In this paper we outline the theoretical background to arguments for including students as partners in pedagogical planning processes. We present examples where students have worked collaboratively in design processes along with the beneficial outcomes of these examples. Finally we focus on some of the implications and opportunities for academic developers of proposing collaborative approaches to pedagogical planning

    Low-Lying Excited States and Low-Temperature Properties of an Alternating Spin-1 / Spin-1/2 Chain : A DMRG study

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    We report spin wave and DMRG studies of the ground and low-lying excited states of uniform and dimerized alternating spin chains. The DMRG procedure is also employed to obtain low-temperature thermodynamic properties of the system. The ground state of a 2N spin system with spin-1 and spin-1/2 alternating from site to site and interacting via an antiferromagnetic exchange is found to be ferrimagnetic with total spin sG=N/2s_G=N/2 from both DMRG and spin wave analysis. Both the studies also show that there is a gapless excitation to a state with spin sG−1s_G-1 and a gapped excitation to a state with spin sG+1s_G+1. Surprisingly, the correlation length in the ground state is found to be very small from both the studies for this gapless system. For this very reason, we show that the ground state can be described by a variational ``ansatz'' of the product type. DMRG analysis shows that the chain is susceptible to a conditional spin-Peierls' instability. The DMRG studies of magnetization, magnetic susceptibility (χ\chi) and specific heat show strong magnetic-field dependence. The product χT\chi T shows a minimum as a function of temperature(TT) at low-magnetic fields and the minimum vanishes at high-magnetic fields. This low-field behaviour is in agreement with earlier experimental observations. The specific heat shows a maximum as a function of temperature and the height of the maximum increases sharply at high magnetic fields. It is hoped that these studies will motivate experimental studies at high-magnetic fields.Comment: 22 pages in latex; 16 eps figures available upon reques

    Dynamical Structure Factor for the Alternating Heisenberg Chain: A Linked Cluster Calculation

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    We develop a linked cluster method to calculate the spectral weights of many-particle excitations at zero temperature. The dynamical structure factor is expressed as a sum of exclusive structure factors, each representing contributions from a given set of excited states. A linked cluster technique to obtain high order series expansions for these quantities is discussed. We apply these methods to the alternating Heisenberg chain around the dimerized limit (λ=0\lambda=0), where complete wavevector and frequency dependent spectral weights for one and two-particle excitations (continuum and bound-states) are obtained. For small to moderate values of the inter-dimer coupling parameter λ\lambda, these lead to extremely accurate calculations of the dynamical structure factors. We also examine the variation of the relative spectral weights of one and two-particle states with bond alternation all the way up to the limit of the uniform chain (λ=1\lambda=1). In agreement with Schmidt and Uhrig, we find that the spectral weight is dominated by 2-triplet states even at λ=1\lambda=1, which implies that a description in terms of triplet-pair excitations remains a good quantitative description of the system even for the uniform chain.Comment: 26 pages, 17 figure

    Interplay Between Time-Temperature-Transformation and the Liquid-Liquid Phase Transition in Water

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    We study the TIP5P water model proposed by Mahoney and Jorgensen, which is closer to real water than previously-proposed classical pairwise additive potentials. We simulate the model in a wide range of deeply supercooled states and find (i) the existence of a non-monotonic ``nose-shaped'' temperature of maximum density line and a non-reentrant spinodal, (ii) the presence of a low temperature phase transition, (iii) the free evolution of bulk water to ice, and (iv) the time-temperature-transformation curves at different densities.Comment: RevTeX4, 4 pages, 4 eps figure

    The effects of a controlled worksite environmental intervention on determinants of dietary behavior and self-reported fruit, vegetable and fat intake

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    BACKGROUND: Eating patterns in Western industrialized countries are characterized by a high energy intake and an overconsumption of (saturated) fat, cholesterol, sugar and salt. Many chronic diseases are associated with unhealthy eating patterns. On the other hand, a healthy diet (low saturated fat intake and high fruit and vegetable intake) has been found important in the prevention of health problems, such as cancer and cardio-vascular disease (CVD). The worksite seems an ideal intervention setting to influence dietary behavior. The purpose of this study is to present the effects of a worksite environmental intervention on fruit, vegetable and fat intake and determinants of behavior. METHODS: A controlled trial that included two different governmental companies (n = 515): one intervention and one control company. Outcome measurements (short-fat list and fruit and vegetable questionnaire) took place at baseline and 3 and 12 months after baseline. The relatively modest environmental intervention consisted of product information to facilitate healthier food choices (i.e., the caloric (kcal) value of foods in groups of products was translated into the number of minutes to perform a certain (occupational) activity to burn these calories). RESULTS: Significant changes in psychosocial determinants of dietary behavior were found; subjects at the intervention worksite perceived more social support from their colleagues in eating less fat. But also counter intuitive effects were found: at 12 months the attitude and self-efficacy towards eating less fat became less positive in the intervention group. No effects were found on self-reported fat, fruit and vegetable intake. CONCLUSION: This environmental intervention was modestly effective in changing behavioral determinant towards eating less fat (social support, self-efficacy and attitude), but ineffective in positively changing actual fat, fruit and vegetable intake of office workers

    Ab initio van der Waals interactions in simulations of water alter structure from mainly tetrahedral to high-density-like

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    The structure of liquid water at ambient conditions is studied in ab initio molecular dynamics simulations using van der Waals (vdW) density-functional theory, i.e. using the new exchange-correlation functionals optPBE-vdW and vdW-DF2. Inclusion of the more isotropic vdW interactions counteracts highly directional hydrogen-bonds, which are enhanced by standard functionals. This brings about a softening of the microscopic structure of water, as seen from the broadening of angular distribution functions and, in particular, from the much lower and broader first peak in the oxygen-oxygen pair-correlation function (PCF), indicating loss of structure in the outer solvation shells. In combination with softer non-local correlation terms, as in the new parameterization of vdW-DF, inclusion of vdW interactions is shown to shift the balance of resulting structures from open tetrahedral to more close-packed. The resulting O-O PCF shows some resemblance with experiment for high-density water (A. K. Soper and M. A. Ricci, Phys. Rev. Lett., 84:2881, 2000), but not directly with experiment for ambient water. However, an O-O PCF consisting of a linear combination of 70% from vdW-DF2 and 30% from experiment on low-density liquid water reproduces near-quantitatively the experimental O-O PCF for ambient water, indicating consistency with a two-liquid model with fluctuations between high- and low-density regions

    Critical animal and media studies: Expanding the understanding of oppression in communication research

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    Critical and communication studies have traditionally neglected the oppression conducted by humans towards other animals. However, our (mis)treatment of other animals is the result of public consent supported by a morally speciesist-anthropocentric system of values. Speciesism or anthroparchy, as much as any other mainstream ideologies, feeds the media and at the same time is perpetuated by them. The goal of this article is to remedy this neglect by introducing the subdiscipline of Critical Animal and Media Studies. Critical Animal and Media Studies takes inspiration both from critical animal studies – which is so far the most consolidated critical field of research in the social sciences addressing our exploitation of other animals – and from the normative-moral stance rooted in the cornerstones of traditional critical media studies. The authors argue that the Critical Animal and Media Studies approach is an unavoidable step forward for critical media and communication studies to engage with the expanded circle of concerns of contemporary ethical thinking

    LOGISTICS IN CONTESTED ENVIRONMENTS

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    This report examines the transport and delivery of logistics in contested environments within the context of great-power competition (GPC). Across the Department of Defense (DOD), it is believed that GPC will strain our current supply lines beyond their capacity to maintain required warfighting capability. Current DOD efforts are underway to determine an appropriate range of platforms, platform quantities, and delivery tactics to meet the projected logistics demand in future conflicts. This report explores the effectiveness of various platforms and delivery methods through analysis in developed survivability, circulation, and network optimization models. Among other factors, platforms are discriminated by their radar cross-section (RCS), noise level, speed, cargo capacity, and self-defense capability. To maximize supply delivered and minimize the cost of losses, the results of this analysis indicate preference for utilization of well-defended convoys on supply routes where bulk supply is appropriate and smaller, and widely dispersed assets on shorter, more contested routes with less demand. Sensitivity analysis on these results indicates system survivability can be improved by applying RCS and noise-reduction measures to logistics assets.Director, Warfare Integration (OPNAV N9I)Major, Israel Defence ForcesCivilian, Singapore Technologies Engineering Ltd, SingaporeCommander, Republic of Singapore NavyCommander, United States NavyCaptain, Singapore ArmyLieutenant, United States NavyLieutenant, United States NavyMajor, Republic of Singapore Air ForceCaptain, United States Marine CorpsLieutenant, United States NavyLieutenant, United States NavyLieutenant, United States NavyLieutenant, United States NavyLieutenant, United States NavyCaptain, Singapore ArmyLieutenant Junior Grade, United States NavyCaptain, Singapore ArmyLieutenant Colonel, Republic of Singapore Air ForceApproved for public release. distribution is unlimite
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