8,768 research outputs found
Probing Proton Strangeness with Time-Like Virtual Compton Scattering
We document that p(gamma,e+e-)p measurements will yield new, important
information about the off-shell time-like nucleon form factors, especially in
the phi meson region (q^2 = M^2_{phi}) governing the phi N couplings
g^{V,T}_{\phi N N}. Calculations for p(gamma,e+e-)p, utilizing vector meson
dominance, predict measurable phi enhancements at high |t| compared to the
expected phi background production from pi, eta and Pomeron exchange. The phi
form factor contribution generates a novel experimental signature for OZI
violation and the proton strangeness content. The phi N couplings are
determined independently from a combined analysis of the neutron electric form
factor and recent high |t| phi photoproduction. The pi, eta and Pomeron
transition form factors are also predicted and the observed pi and eta
transition moments are reproduced.Comment: 9 pages, 6 figure
Boundary regularity for a family of overdetermined problems for the Helmholtz equation
AbstractIf a nonconstant solution u of the Helmholtz equation exists on a bounded domain with u satisfying overdetermined boundary conditions (u and its normal derivative both required to be constant on the boundary), then under certain assumptions the boundary of the domain is proved to be real-analytic. Under weaker assumptions, if a real-analytic portion of the boundary has a real-analytic extension, then that extension must also be part of the boundary. Also, an explicit formula for u is given and a condition (which does not involve u) is given for a bounded domain to have such a solution u defined on it. Both of these last results involve acoustic single- and double-layer potentials
Linearized large signal modeling, analysis, and control design of phase-controlled series-parallel resonant converters using state feedback
This paper proposes a linearized large signal state-space model for the fixed-frequency phase-controlled series-parallel resonant converter. The proposed model utilizes state feedback of the output filter inductor current to perform linearization. The model combines multiple-frequency and average state-space modeling techniques to generate an aggregate model with dc state variables that are relatively easier to control and slower than the fast resonant tank dynamics. The main objective of the linearized model is to provide a linear representation of the converter behavior under large signal variation which is suitable for faster simulation and large signal estimation/calculation of the converter state variables. The model also provides insight into converter dynamics as well as a simplified reduced order transfer function for PI closed-loop design. Experimental and simulation results from a detailed switched converter model are compared with the proposed state-space model output to verify its accuracy and robustness
Perceptual bias, more than age, impacts on eye movements during face processing
Consistent with the right hemispheric dominance for face processing, a left perceptual bias (LPB) is typically demonstrated by younger adults viewing faces and a left eye movement bias has also been revealed. Hemispheric asymmetry is predicted to reduce with age and older adults have demonstrated a weaker LPB, particularly when viewing time is restricted. What is currently unclear is whether age also weakens the left eye movement bias. Additionally, a right perceptual bias (RPB) for facial judgments has less frequently been demonstrated, but whether this is accompanied by a right eye movement bias has not been investigated. To address these issues older and younger adults’ eye movements and gender judgments of chimeric faces were recorded in two time conditions. Age did not significantly weaken the LPB or eye movement bias; both groups looked initially to the left side of the face and made more fixations when the gender judgment was based on the left side. A positive association was found between LPB and initial saccades in the freeview condition and with all eye movements (initial saccades, number and duration of fixations) when time was restricted. The accompanying eye movement bias revealed by LPB participants contrasted with RPB participants who demonstrated no eye movement bias in either time condition. Consequently, increased age is not clearly associated with weakened perceptual and eye movement biases. Instead an eye movement bias accompanies an LPB (particularly under restricted viewing time conditions) but not an RPB
Mining Geology of Coals in Western Kentucky
Each of the most heavily mined coal seams in the Western Kentucky Coal Field, as indicated by analyses, mine visits, and discussions with mine inspectors and engineers, has its own roof and floor characteristics. Also, because roof rocks above several of the seams are laterally continuous (especially in the Carbondale Formation), roof characteristics related to rock type are often widespread and continuous between mines. This chart discusses the mining geology of three western Kentucky coal beds, highlighted on the stratigraphic column shown in Figure 1.
Additional mining obstacles that can affect all coal beds and roof strata are (1) tectonic faulting, which is prevalent in western Kentucky, (2) fractures related to low cover and past mining, and (3) fractures related to the regional tectonic stress field
A triadic view of truck driver satisfaction
In this research, the authors surveyed three groups concerning job satisfaction: experienced drivers, new drivers, and managers. Statistical tests were conducted using a sample of 196 new drivers, 145 experienced drivers, and 59 managers from a large TL firm based in the U.S. The results suggest that many discrepancies exist on driver satisfaction among the three perspectives. In particular, new drivers provide managers with opportunities and challenges for satisfaction. Given the current state of the trucking industry, managers will likely benefit from approaching this segment of drivers differently to meet their expectations and keep them from leaving their firms
Incremental Cost Estimates for the Patient-Centered Medical Home
Based on data from thirty-five primary care practices, analyzes the costs associated with the medical home model, in which primary care practices also provide care coordination, patient education, and related services. Considers implications
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