5,336 research outputs found
Solving Potential Scattering Equations without Partial Wave Decomposition
Considering two-body integral equations we show how they can be dimensionally
reduced by integrating exactly over the azimuthal angle of the intermediate
momentum. Numerical solution of the resulting equation is feasible without
employing a partial-wave expansion. We illustrate this procedure for the
Bethe-Salpeter equation for pion-nucleon scattering and give explicit details
for the one-nucleon-exchange term in the potential. Finally, we show how this
method can be applied to pion photoproduction from the nucleon with
rescattering being treated so as to maintain unitarity to first order in the
electromagnetic coupling. The procedure for removing the azimuthal angle
dependence becomes increasingly complex as the spin of the particles involved
increases.Comment: 15 pages, 4 figure
What Should EDA Fund? Developing a Model for Pre-Assessment of Economic Development Investments
This paper describes the completion of a ācomprehensive study of regionalismā that was conducted by a joint team of economists and economic development specialists for the Economic Development Administration (EDA). The project consisted of two main activities: an examination of the factors associated with economic development success and the creation of a practical interactive tool for EDA project assessment and comparison. Findings from surveys, interviews, and project case studies are discussed in terms of their support for a positive relationship between successful economic development efforts and factors such as leadership and private investment. Also, the authors discuss the creation of a quantitative assessment model utilizing well-known approaches such as economic impact multipliers and cluster theory. The primary contribution of this work to the existing body of EDA-focused research and evaluation literature is introducing a means of using standardized scores, also known as z-scores, to compare and assess economic development projects across both industries and regions.regional economic development, economic impact, assessment model, EDA, z-score
Near infrared spectroscopy of the type IIn SN 2010jl: evidence for high velocity ejecta
The Type IIn supernova SN 2010jl was relatively nearby and luminous, allowing
detailed studies of the near-infrared (NIR) emission. We present 1 - 2.4 micron
spectroscopy over the age range of 36 - 565 days from the earliest detection of
the supernova. On day 36, the H lines show an unresolved narrow emission
component along with a symmetric broad component that can be modeled as the
result of electron scattering by a thermal distribution of electrons. Over the
next hundreds of days, the broad components of the H lines shift to the blue by
700 km/s, as is also observed in optical lines. The narrow lines do not show a
shift, indicating they originate in a different region. He I 1.0830 and 2.0587
micron lines both show an asymmetric broad emission component, with a shoulder
on the blue side that varies in prominence and velocity from -5500 km/s on day
108 to -4000 km/s on day 219. This component may be associated with the higher
velocity flow indicated by X-ray observations of the supernova. The absence of
the feature in the H lines suggests that this is from a He rich ejecta flow.
The He I 1.0830 micron feature has a narrow P Cygni line, with absorption
extending to ~100 km/s and strengthening over the first 200 days, and an
emission component which weakens with time. At day 403, the continuum emission
becomes dominated by a blackbody spectrum with a temperature of ~1900 K,
suggestive of dust emission.Comment: 17 pages, 18 figure
Inexpensive and Portable System for Dexterous High-Density Myoelectric Control of Multiarticulate Prostheses
Multiarticulate bionic arms are now capable of mimicking the endogenous
movements of the human hand. 3D-printing has reduced the cost of prosthetic
hands themselves, but there is currently no low-cost alternative to dexterous
electromyographic (EMG) control systems. To address this need, we developed an
inexpensive (~$675) and portable EMG control system by integrating low-cost
microcontrollers with an EMG acquisition device. We validated signal
acquisition by comparing the signal-to-noise ratio (SNR) of our system with
that of a high-end research-grade system. We also demonstrate the ability to
use the low-cost control system for proportional and independent control of
various prosthetic hands in real-time. We found that the SNR of the low-cost
control system was statistically no worse than 44% of the SNR of a
research-grade control system. The RMSEs of predicted hand movements (from a
modified Kalman filter) were typically a few percent better than, and not more
than 6% worse than, RMSEs of a research-grade system for up to six degrees of
freedom when only relatively few (six) EMG electrodes were used. However, RMSEs
were generally higher than RMSEs of research-grade systems that utilize
considerably more (32) EMG electrodes, guiding future work towards increasing
electrode count. Successful instantiation of this low-cost control system
constitutes an important step towards the commercialization and wide-spread
availability of dexterous bionic hands.Comment: IEEE EMBC 202
The Weiss conjecture and weak norms
In this note we show that for analytic semigroups the so-called Weiss
condition of uniform boundedness of the operators Re(\lambda)^\einhalb
C(\lambda+A)^{-1}, \qquad Re(\lambda)>0 on the complex right half plane and
weak Lebesgue --admissibility are equivalent. Moreover, we show
that the weak Lebesgue norm is best possible in the sense that it is the
endpoint for the 'Weiss conjecture' within the scale of Lorentz spaces
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