Fitness Norms for the Plank Exercise

PURPOSE: Adequate strength of core musculature is critical for optimal physical performance and postural control. Currently, standards for core musculature strength and stability have not been established. This study sought to determine normative fitness measurements of core musculature endurance using the plank exercise. METHODS: 168 collegiate male and female participants (18-25 years of age) were recruited. Participants were instructed in plank positioning; elbows bent at 90° directly below the shoulders, hands unclasped, feet placed hip width apart with ankles at 90° and pelvis tilted in the neutral position. After a 5-minute warm-up, participants were told to maintain the plank position as long as possible until complete fatigue was reached. The test was terminated if proper form was broken. The total time held in proper plank position was recorded. RESULTS: The mean time held in the plank position was 96.25 + 43.16 and 116.58 + 65.49 seconds for females and males, respectively. For females, quartiles showed that the 25th percentile was 63 seconds, the 50th percentile was 90 seconds, while the 75th percentile was 121 seconds. Quartiles for males were 77seconds, 106 seconds and 128.5 seconds for the 25th, 50th and 75th percentiles, respectively. CONCLUSION: This study provides normative values for the plank exercise that can be added to current fitness appraisal protocols to assess core muscular endurance. These data suggest that 1.50 minutes in females and 1.77 minutes in males (50th percentile values) could be considered average duration of the plank exercise for this age group

Geothermal reservoir engineering research

The Stanford University research program on the study of stimulation and reservoir engineering of geothermal resources commenced as an interdisciplinary program in September, 1972. The broad objectives of this program have been: (1) the development of experimental and computational data to evaluate the optimum performance of fracture-stimulated geothermal reservoirs; (2) the development of a geothermal reservoir model to evaluate important thermophysical, hydrodynamic, and chemical parameters based on fluid-energy-volume balances as part of standard reservoir engineering practice; and (3) the construction of a laboratory model of an explosion-produced chimney to obtain experimental data on the processes of in-place boiling, moving flash fronts, and two-phase flow in porous and fractured hydrothermal reservoirs

“I was like an alien”: Exploring how Indigenous students succeed in university studies

This article explores the strategies used by Indigenous students attending three Canadian universities (in Nova Scotia, Ontario, and Manitoba) to find success in their studies. As part of a larger study on the success strategies of students who have been traditionally underrepresented in Canadian universities, this article draws on the responses of students who self-identify as Indigenous and insights from a key informant. We argue that the voices of Indigenous students are essential in the processes of institutional decolonizing and reconciliation and of reimagining universities as inclusive, equitable spaces for Indigenous students and their academic successCet article examine les stratégies utilisées par les étudiants Autochtones qui fréquentent trois universités canadiennes (en Nouvelle-Écosse, en Ontario et au Manitoba) pour réussir leurs études. Dans le cadre d'une étude plus vaste sur les stratégies de réussite des étudiants traditionnellement sous-représentés dans les universités canadiennes, cet article s'appuie sur les réponses d'étudiants qui s'identifient comme Autochtones et sur les idées d'un informateur clé. Nous soutenons que les voix d’étudiants Autochtones sont essentielles dans les processus de décolonisation et de réconciliation institutionnelles et de réinvention des universités en tantqu'espaces équitables inclusifs pour les étudiants Autochtones et leur réussite scolaire

Many-body Green's function theory for electron-phonon interactions: the Kadanoff-Baym approach to spectral properties of the Holstein dimer

We present a Kadanoff-Baym formalism to study time-dependent phenomena for systems of interacting electrons and phonons in the framework of many-body perturbation theory. The formalism takes correctly into account effects of the initial preparation of an equilibrium state, and allows for an explicit time-dependence of both the electronic and phononic degrees of freedom. The method is applied to investigate the charge neutral and non-neutral excitation spectra of a homogeneous, two-site, two-electron Holstein model. This is an extension of a previous study of the ground state properties in the Hartree (H), partially self-consistent Born (Gd) and fully self-consistent Born (GD) approximations published in Ref. [arXiv:1403.2968]. We show that choosing a homogeneous ground state solution leads to unstable dynamics for a sufficiently strong interaction, and that allowing a symmetry-broken state prevents this. The instability is caused by the bifurcation of the ground state and understood physically to be connected with the bipolaronic crossover of the exact system. This mean-field instability persists in the partially self-consistent Born approximation but is not found for the fully self-consistent Born approximation. By understanding the stability properties, we are able to study the linear response regime by calculating the density-density response function by time-propagation. This functions amounts to a solution of the Bethe-Salpeter equation with a sophisticated kernel. The results indicate that none of the approximations is able to describe the response function during or beyond the bipolaronic crossover for the parameters investigated. Overall, we provide an extensive discussion on when the approximations are valid, and how they fail to describe the studied exact properties of the chosen model system.Comment: 12 figure

Circum-Arctic Late Tertiary/Early Pleistocene Stratigraphy And Environments - A Preface

...During the 1980s the Geological Survey of Canada (GSC) and the U.S. Geological Survey (USGS) initiated a program of joint workshops and cooperative field excursions. The first meeting took place in Calgary, Alberta, in 1984. It dealt with correlation of Quaternary deposits in northwestern North America, but touched on the Tertiary. A second GSC/USGS workshop in early 1987 concerned the Quaternary history of interior basins of Alaska and Canada, but once again the Tertiary became an item of discussion because some of the basins contain a thick sequence of Pliocene and Miocene sediments. It was apparent from the questions that arose at these meetings that there was a need for a dedicated forum on the late Tertiary. The authors organized and convened a workshop with that theme in Denver, Colorado, in October 1987. The papers in this special issue are based on presentations and discussions at that meeting. ..

When Torts Met Civil Procedure: A Curricular Coupling

Law students must become adept at understanding how various bodies of law interact-supporting, balancing, and even conflicting with each other. This article describes an attempt to achieve these goals by merging two canonical first-year courses, civil procedure and torts, into an integrated class titled ‘Introduction to Civil Litigation’. Our most pressing motivation was concern that students who study civil procedure and torts in isolation develop a skewed, unrealistic view of how law works in the real world. By combining these courses, we hoped to teach students early in their careers to approach problems more like practicing lawyers, who must deal with multiple bodies of law simultaneously. And while the course did yield a higher level of practice readiness, the experience also brought unexpected rewards to both students and faculty. As we developed and refined the course, we discovered that we were not just merging two courses. We were bringing together two different perspectives on how the law functions. We came to believe that more can be gained by viewing torts and civil procedure together than by studying them apart. Torts and Civil Procedure tell different sides of the same story

Creation and pinning of vortex-antivortex pairs

Computer modeling is reported about the creation and pinning of a magnetic vortex-antivortex (V-AV) pair in a superconducting thin film, due to the magnetic field of a vertical magnetic dipole above the film, and two antidot pins inside the film. For film thickness $= 0.1\xi$, $\kappa = 2$, and no pins, we find the film carries two V-AV pairs at steady state in the imposed flux range $2.10\Phi_0 < \Phi^+ < 3.0\Phi_0$, and no pairs below. With two antidot pins suitably introduced into the film, a single V-AV pair can be stable in the film for $\Phi^+ \ge 1.3\Phi_0$. At pin separation $\ge 17\xi$, we find the V-AV pair remains pinned after the dipole field is removed, and, so can represent a 1 for a nonvolatile memory.Comment: 8 pages, 6 figure

Optimized energy calculation in lattice systems with long-range interactions

We discuss an efficient approach to the calculation of the internal energy in numerical simulations of spin systems with long-range interactions. Although, since the introduction of the Luijten-Bl\"ote algorithm, Monte Carlo simulations of these systems no longer pose a fundamental problem, the energy calculation is still an O(N^2) problem for systems of size N. We show how this can be reduced to an O(N logN) problem, with a break-even point that is already reached for very small systems. This allows the study of a variety of, until now hardly accessible, physical aspects of these systems. In particular, we combine the optimized energy calculation with histogram interpolation methods to investigate the specific heat of the Ising model and the first-order regime of the three-state Potts model with long-range interactions.Comment: 10 pages, including 8 EPS figures. To appear in Phys. Rev. E. Also available as PDF file at http://www.cond-mat.physik.uni-mainz.de/~luijten/erikpubs.htm

Tropical Dominating Sets in Vertex-Coloured Graphs

Given a vertex-coloured graph, a dominating set is said to be tropical if every colour of the graph appears at least once in the set. Here, we study minimum tropical dominating sets from structural and algorithmic points of view. First, we prove that the tropical dominating set problem is NP-complete even when restricted to a simple path. Then, we establish upper bounds related to various parameters of the graph such as minimum degree and number of edges. We also give upper bounds for random graphs. Last, we give approximability and inapproximability results for general and restricted classes of graphs, and establish a FPT algorithm for interval graphs.Comment: 19 pages, 4 figure