1,030 research outputs found

    Filling the Void: A Low Cost, High-Yield Method to Addressing Incidental Findings in Trauma Patients

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    In this study we: Report the incidence of incidental findings in a suburban trauma center treating primarily blunt and elderly trauma Propose simple solutions to increase the rate of disclosure to patientshttps://jdc.jefferson.edu/patientsafetyposters/1070/thumbnail.jp

    Group properties and invariant solutions of a sixth-order thin film equation in viscous fluid

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    Using group theoretical methods, we analyze the generalization of a one-dimensional sixth-order thin film equation which arises in considering the motion of a thin film of viscous fluid driven by an overlying elastic plate. The most general Lie group classification of point symmetries, its Lie algebra, and the equivalence group are obtained. Similar reductions are performed and invariant solutions are constructed. It is found that some similarity solutions are of great physical interest such as sink and source solutions, travelling-wave solutions, waiting-time solutions, and blow-up solutions.Comment: 8 page

    Kinematic evaluation of physical impairments of an elite Paralympic karateka

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    Karate is a Japanese martial art that counts millions of practitioners worldwide and that is spreading also in Paralympic competitions, requiring accurate categories definition for disabled athletes. The aim of the study is to present kinematic data of an elite Paralympic karateka, in comparison with able-bodied athletes. The authors also aim to promote a better classification within the discipline, based on objective biomechanical evaluations of physical impairments. A male black belt Paralympic karateka (age: 36 y; body weight: 75.5 kg; height: 173 cm) with lower limbs impairments was evaluated. The athlete had been performing high level karate for 20 years before the disability took place. After the post-operative rehabilitation, he attended 3/4 sessions of para- karate training per week. He performed a standardized sequence of movements, involving a sequence of offensive and defensive techniques, (kata) from traditional Shotokan karate. Joints and body Center of Mass (CoM) kinematics were collected with an optoelectronic motion capture system and compared with those obtained in two groups of able-bodied (elite and amateurs) athletes from a previous study1. Knee angular range of motion (RoM) and peak angular velocity were obtained. Coordinates of CoM were estimated, using the Segmental Centroid Method2, along with CoM average velocity and acceleration. To assess differences between Paralympic karateka and able-bodied groups, the one-sample t-test was performed. The sequence performed by the karateka lasted more than in both able-bodied groups. CoM average velocity and acceleration decreased in comparison with elite karateka. Knees range of movement and peak angular velocity were similar to amateur but lower than elite athletes. Results show that the physical impairments negatively affected the function of lower limbs in the Paralympic athlete. Fundamental skills in karate elite performance (dynamic balance control and joint RoM and angular velocity) were reduced

    Thin film evolution equations from (evaporating) dewetting liquid layers to epitaxial growth

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    In the present contribution we review basic mathematical results for three physical systems involving self-organising solid or liquid films at solid surfaces. The films may undergo a structuring process by dewetting, evaporation/condensation or epitaxial growth, respectively. We highlight similarities and differences of the three systems based on the observation that in certain limits all of them may be described using models of similar form, i.e., time evolution equations for the film thickness profile. Those equations represent gradient dynamics characterized by mobility functions and an underlying energy functional. Two basic steps of mathematical analysis are used to compare the different system. First, we discuss the linear stability of homogeneous steady states, i.e., flat films; and second the systematics of non-trivial steady states, i.e., drop/hole states for dewetting films and quantum dot states in epitaxial growth, respectively. Our aim is to illustrate that the underlying solution structure might be very complex as in the case of epitaxial growth but can be better understood when comparing to the much simpler results for the dewetting liquid film. We furthermore show that the numerical continuation techniques employed can shed some light on this structure in a more convenient way than time-stepping methods. Finally we discuss that the usage of the employed general formulation does not only relate seemingly not related physical systems mathematically, but does as well allow to discuss model extensions in a more unified way

    Transmission of High-Power Electron Beams Through Small Apertures

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    Tests were performed to pass a 100 MeV, 430 kWatt c.w. electron beam from the energy-recovery linac at the Jefferson Laboratory's FEL facility through a set of small apertures in a 127 mm long aluminum block. Beam transmission losses of 3 p.p.m. through a 2 mm diameter aperture were maintained during a 7 hour continuous run.Comment: arXiv admin note: text overlap with arXiv:1305.019

    The McKean-Vlasov Equation in Finite Volume

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    We study the McKean--Vlasov equation on the finite tori of length scale LL in dd--dimensions. We derive the necessary and sufficient conditions for the existence of a phase transition, which are based on the criteria first uncovered in \cite{GP} and \cite{KM}. Therein and in subsequent works, one finds indications pointing to critical transitions at a particular model dependent value, ξ♯\theta^{\sharp} of the interaction parameter. We show that the uniform density (which may be interpreted as the liquid phase) is dynamically stable for Ξ<ξ♯\theta < \theta^{\sharp} and prove, abstractly, that a {\it critical} transition must occur at Ξ=ξ♯\theta = \theta^{\sharp}. However for this system we show that under generic conditions -- LL large, d≄2d \geq 2 and isotropic interactions -- the phase transition is in fact discontinuous and occurs at some \theta\t < \theta^{\sharp}. Finally, for H--stable, bounded interactions with discontinuous transitions we show that, with suitable scaling, the \theta\t(L) tend to a definitive non--trivial limit as L→∞L\to\infty

    Implementation of a Three-Semester Concurrent Engineering Design Sequence for Lower-Division Engineering Students

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    Over the past decade the software products available for solid modeling, dynamic, stress, thermal, and flow analysis, and computer-aiding manufacturing (CAM) have become more powerful, affordable, and easier to use.  At the same time it has become increasingly important for students to gain concurrent engineering design and systems integration experience. The purpose of this paper is to communicate the dramatic effect that the new software has had on the way that mechanical drawing and engineering design are taught at Daniel Webster College (DWC). The two year design experience at DWC is more extensive than the design experience that students normally have during the first two years of most four-year engineering programs. The evolution of this design experience will be presented.  Three of the presenters of this paper are students. Two will present robotic arm projects; the third will present a supersonic gun project

    Measured Radiation and Background Levels During Transmission of Megawatt Electron Beams Through Millimeter Apertures

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    We report measurements of photon and neutron radiation levels observed while transmitting a 0.43 MW electron beam through millimeter-sized apertures and during beam-off, but accelerating gradient RF-on, operation. These measurements were conducted at the Free-Electron Laser (FEL) facility of the Jefferson National Accelerator Laboratory (JLab) using a 100 MeV electron beam from an energy-recovery linear accelerator. The beam was directed successively through 6 mm, 4 mm, and 2 mm diameter apertures of length 127 mm in aluminum at a maximum current of 4.3 mA (430 kW beam power). This study was conducted to characterize radiation levels for experiments that need to operate in this environment, such as the proposed DarkLight Experiment. We find that sustained transmission of a 430 kW continuous-wave (CW) beam through a 2 mm aperture is feasible with manageable beam-related backgrounds. We also find that during beam-off, RF-on operation, multipactoring inside the niobium cavities of the accelerator cryomodules is the primary source of ambient radiation when the machine is tuned for 130 MeV operation.Comment: 9 pages, 11 figures, submitted to Nuclear Instruments and Methods in Physics Research Section

    Analysis of cancellation in two-dimensional magnetohydrodynamic turbulence

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    A signed measure analysis of two-dimensional intermittent magnetohydrodynamic turbulence is presented. This kind of analysis is performed to characterize the scaling behavior of the sign-oscillating flow structures, and their geometrical properties. In particular, it is observed that cancellations between positive and negative contributions of the field inside structures, are inhibited for scales smaller than the Taylor microscale, and stop near the dissipative scale. Moreover, from a simple geometrical argument, the relationship between the cancellation exponent and the typical fractal dimension of the structures in the flow is obtained.Comment: 21 pages, 5 figures (3 .jpg not included in the latex file
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