On an Alternative Parametrization for the Theory of Complex Spectra

The purpose of this letter is threefold : (i) to derive, in the framework of a new parametrization, some compact formulas of energy averages for the electrostatic interaction within an (nl)N configuration, (ii) to describe a new generating function for obtaining the number of states with a given spin angular momentum in an (nl)N configuration, and (iii) to report some apparently new sum rules, actually a by-product of (i), for SU(2) > U(1) coupling coefficients.Comment: Published in Physics Letters A 147, 417-422 (1990

‘But Now I Yearn for a … Story About a Cripple Who Isn’t Cured’: Representations of Disability in Middle Grade and Young Adult Literature

Disabled youth and teens, like those from other marginalized identities, need authentic and honest representations of themselves in books, but disability has long been excluded from many calls for more diverse books. This critical analysis examines 10 middle grade and young adult books for stereotypical portrayals of disabled people and how the authors cultivate or subvert those tropes. It also discusses how disability is viewed in society, the language of disability, and the necessity of critically engaging with literature.Master of Science in Library Scienc

Children with Cancer and Blood Diseases Experience Positive Physical and Psychological Effects from Massage Therapy

Background: Previous research has reported positive effects of massage therapy (MT) on premature infants, children with asthma, arthritis and other illnesses. Although significant effects have been demonstrated with the use of MT with children, research regarding children with cancer and blood disease is needed. Purpose: This study measured the physical and psychological effects of MT on pediatric oncology and hematology patients. The study hypotheses tested the effects MT for physical and psychological symptom relief. Setting: Cancer Center, Shands Hospital at the University of Florida, Gainesville. Research Design: Randomized non-blinded prospective study. Measures of physical health and mental wellbeing were completed before, during, and after four sessions were implemented. Descriptive statistics and 2 (treatment) X 2 (time) one-way ANOVAs were used to analyze data. Participants: Thirty children with cancer and blood disease, ages 6 months to 17 years old. Intervention: Treatment group received 20 minute sessions of Swedish MT once a day for approximately 4 days (inpatient) or once a week for approximately four weeks (outpatient) vs. no MT for the control group. Results: Treatment group showed significant improvement in both psychological stress [STAI-C: State (F [1, 28] = 24.63, p < .001), Trait (F [1, 28] = 12.83, p < .001) and emotional state (F [1, 28] = 157.79, p < .001)], physical measures [muscle soreness (F [1, 28] = 148.20,

Addressing Health Disparities Among Homeless in Alachua County through Community-Based Participatory Research.

Introduction. In states such as Florida that did not expand Medicaid, a large number of economically disadvantaged individuals do not qualify for subsidies to buy health insurance through the Affordable Care Act (ACA) 2. This leaves the health needs of Florida’s homeless population largely unaddressed. Nearly 48.1% of Alachua County’s homeless population has disabling conditions 16. This confirms a pressing need to understand the homeless population\u27s healthcare needs, knowledge, and barriers in accessing healthcare. Methods. We used a Community-Based Participatory Research model in conducting health fairs and needs assessment surveys, incentivizing participation, and providing education about existing resources. The surveys were conducted at two homeless meal service sites and consisted of 22 questions regarding access to healthcare, utilization, and satisfaction. Health fairs consisted of blood pressure, blood glucose, and mental health screening. Patient participation was encouraged through games, prizes and food. Results. Of the population we surveyed, 100% have income levels below $11,490, therefore all uninsured fall into the ACA coverage gap. Those less than 65 years of age do not qualify for Medicare unless disabled. Some qualify for Medicaid as shown in tables. Fifty-eight percent were uninsured and did not get any treatment for their illnesses. Additionally, 67% had no knowledge of free local healthcare clinics. Discussion/Conclusion. The majority of this population falls into the ACA Coverage Gap, lacks knowledge about free community clinics, and inappropriately uses the ED. Future implications of this research involve advocacy to expand Medicaid in Florida and enroll those who are eligible for health insurance. Vital goals include outreach by free healthcare clinics to make healthcare more accessible, as well as building trust with the community through continued outreach initiatives. A community-Based Participatory Research Model is an effective tool to increasing collaboration among diverse members of the community in order to bring meaningful and positive change to the health of populations

Sheath parameters for non-Debye plasmas: simulations and arc damage

This paper describes the surface environment of the dense plasma arcs that damage rf accelerators, tokamaks and other high gradient structures. We simulate the dense, non-ideal plasma sheath near a metallic surface using Molecular Dynamics (MD) to evaluate sheaths in the non-Debye region for high density, low temperature plasmas. We use direct two-component MD simulations where the interactions between all electrons and ions are computed explicitly. We find that the non-Debye sheath can be extrapolated from the Debye sheath parameters with small corrections. We find that these parameters are roughly consistent with previous PIC code estimates, pointing to densities in the range $10^{24} - 10^{25}\mathrm{m}^{-3}$. The high surface fields implied by these results could produce field emission that would short the sheath and cause an instability in the time evolution of the arc, and this mechanism could limit the maximum density and surface field in the arc. These results also provide a way of understanding how the "burn voltage" of an arc is generated, and the relation between self sputtering and the burn voltage, while not well understood, seems to be closely correlated. Using these results, and equating surface tension and plasma pressure, it is possible to infer a range of plasma densities and sheath potentials from SEM images of arc damage. We find that the high density plasma these results imply and the level of plasma pressure they would produce is consistent with arc damage on a scale 100 nm or less, in examples where the liquid metal would cool before this structure would be lost. We find that the sub-micron component of arc damage, the burn voltage, and fluctuations in the visible light production of arcs may be the most direct indicators of the parameters of the dense plasma arc, and the most useful diagnostics of the mechanisms limiting gradients in accelerators.Comment: 8 pages, 16 figure

A Fast Parallel Poisson Solver on Irregular Domains Applied to Beam Dynamic Simulations

We discuss the scalable parallel solution of the Poisson equation within a Particle-In-Cell (PIC) code for the simulation of electron beams in particle accelerators of irregular shape. The problem is discretized by Finite Differences. Depending on the treatment of the Dirichlet boundary the resulting system of equations is symmetric or `mildly' nonsymmetric positive definite. In all cases, the system is solved by the preconditioned conjugate gradient algorithm with smoothed aggregation (SA) based algebraic multigrid (AMG) preconditioning. We investigate variants of the implementation of SA-AMG that lead to considerable improvements in the execution times. We demonstrate good scalability of the solver on distributed memory parallel processor with up to 2048 processors. We also compare our SAAMG-PCG solver with an FFT-based solver that is more commonly used for applications in beam dynamics

On the indefinite Helmholtz equation: complex stretched absorbing boundary layers, iterative analysis, and preconditioning

This paper studies and analyzes a preconditioned Krylov solver for Helmholtz problems that are formulated with absorbing boundary layers based on complex coordinate stretching. The preconditioner problem is a Helmholtz problem where not only the coordinates in the absorbing layer have an imaginary part, but also the coordinates in the interior region. This results into a preconditioner problem that is invertible with a multigrid cycle. We give a numerical analysis based on the eigenvalues and evaluate the performance with several numerical experiments. The method is an alternative to the complex shifted Laplacian and it gives a comparable performance for the studied model problems

Hydrostatic Level Sensors as High Precision Ground Motion Instrumentation for Tevatron and Other Energy Frontier Accelerators

Particle accelerators pushed the limits of our knowledge in search of the answers to most fundamental questions about micro-world and our Universe. In these pursuits, accelerators progressed to higher and higher energies and particle beam intensities as well as increasingly smaller and smaller beam sizes. As the result, modern existing and planned energy frontier accelerators demand very tight tolerances on alignment and stability of their elements: magnets, accelerating cavities, vacuum chambers, etc. In this article we describe the instruments developed for and used in such accelerators as Fermilab's Tevatron (FNAL, Batavia, IL USA) and for the studies toward an International Linear Collider (ILC). The instrumentation includes Hydrostatic Level Sensors (HLS) for very low frequency measurements. We present design features of the sensors, outline their technical parameters, describe test and calibration procedures and discuss different regimes of operation. Experimental results of the ground motion measurements with these detectors will be presented in subsequent paper

On the equivalence between the Scheduled Relaxation Jacobi method and Richardson's non-stationary method

The Scheduled Relaxation Jacobi (SRJ) method is an extension of the classical Jacobi iterative method to solve linear systems of equations (Au=b) associated with elliptic problems. It inherits its robustness and accelerates its convergence rate computing a set of P relaxation factors that result from a minimization problem. In a typical SRJ scheme, the former set of factors is employed in cycles of M consecutive iterations until a prescribed tolerance is reached. We present the analytic form for the optimal set of relaxation factors for the case in which all of them are strictly different, and find that the resulting algorithm is equivalent to a non-stationary generalized Richardson's method where the matrix of the system of equations is preconditioned multiplying it by D=diag(A). Our method to estimate the weights has the advantage that the explicit computation of the maximum and minimum eigenvalues of the matrix A (or the corresponding iteration matrix of the underlying weighted Jacobi scheme) is replaced by the (much easier) calculation of the maximum and minimum frequencies derived from a von Neumann analysis of the continuous elliptic operator. This set of weights is also the optimal one for the general problem, resulting in the fastest convergence of all possible SRJ schemes for a given grid structure. The amplification factor of the method can be found analytically and allows for the exact estimation of the number of iterations needed to achieve a desired tolerance. We also show that with the set of weights computed for the optimal SRJ scheme for a fixed cycle size it is possible to estimate numerically the optimal value of the parameter ω in the Successive Overrelaxation (SOR) method in some cases. Finally, we demonstrate with practical examples that our method also works very well for Poisson-like problems in which a high-order discretization of the Laplacian operator is employed (e.g., a 9- or 17-points discretization). This is of interest since the former discretizations do not yield consistently ordered A matrices and, hence, the theory of Young cannot be used to predict the optimal value of the SOR parameter. Furthermore, the optimal SRJ schemes deduced here are advantageous over existing SOR implementations for high-order discretizations of the Laplacian operator in as much as they do not need to resort to multi-coloring schemes for their parallel implementation