30,035 research outputs found
A combined R-matrix eigenstate basis set and finite-differences propagation method for the time-dependent Schr\"{od}dinger equation: the one-electron case
In this work we present the theoretical framework for the solution of the
time-dependent Schr\"{o}dinger equation (TDSE) of atomic and molecular systems
under strong electromagnetic fields with the configuration space of the
electron's coordinates separated over two regions, that is regions and
. In region the solution of the TDSE is obtained by an R-matrix basis
set representation of the time-dependent wavefunction. In region a grid
representation of the wavefunction is considered and propagation in space and
time is obtained through the finite-differences method. It appears this is the
first time a combination of basis set and grid methods has been put forward for
tackling multi-region time-dependent problems. In both regions, a high-order
explicit scheme is employed for the time propagation. While, in a purely
hydrogenic system no approximation is involved due to this separation, in
multi-electron systems the validity and the usefulness of the present method
relies on the basic assumption of R-matrix theory, namely that beyond a certain
distance (encompassing region ) a single ejected electron is distinguishable
from the other electrons of the multi-electron system and evolves there (region
II) effectively as a one-electron system. The method is developed in detail for
single active electron systems and applied to the exemplar case of the hydrogen
atom in an intense laser field.Comment: 13 pages, 6 figures, submitte
Maclisp extensions
A common subset of selected facilities available in Maclisp and its derivatives (PDP-10 and Multics Maclisp, Lisp Machine Lisp (Zetalisp), and NIL) is decribed. The object is to add in writing code which can run compatibly in more than one of these environments
PAIN TOLERANCE: DIFFERENCES ACCORDING TO SEX AND SPORT
Numerous studies have independently examined gender differences in experimental pain, but few have examined the different surfaces of play that may influence an athlete’s pain tolerance. The present experiment examined the effects of race, gender, and sport on experimental pain tolerance and threshold. Forty (10 female basketball, 10 male basketball, 10 female soccer, 10 male soccer) collegiate athletes were given two pain tolerance tests consisting of a cold water intolerance test (CWIT) and a tourniquet pain test (TPT). The CWIT measured the maximum length of time that each athlete could place his/her hand in an ice cold bucket of water (2°C). The TPT measured the maximum length of time that each athlete could repeatedly squeeze a hand grip dynamometer while blood was occluded from the arm. A series of ANOVA tests determined if there were significant differences in pain tolerances between race, gender, and sport Based on the results, there are no differences in pain tolerance when comparing sport; however, there is a significant difference (p < 0.05) in pain tolerance when comparing race and gender. The CWIT shows that white females have a significantly higher pain tolerance than non-white females; however, there is no significant data that shows that white males have a higher pain tolerance than non-white males. These data are beneficial for physicians, trainers, coaches, etc. because they now know to treat injuries of both males and females of indoor and outdoor sports equally because sport has no effect on pain tolerance
Readiness for competitive positioning: A managerial checklist
Competitive positioning is improved by following best practices regarding analysis of competition, consumers, industry dynamics, SBU capabilities, market deliverables and fit, and profit potential of various positions. Only then can positions be identified that are relevant, worthwhile, achievable and defendable. Literature acknowledges the process requirements but few management tools are available to aid in this task. This paper proposes a readiness checklist that helps insure best practices are followed and is a precursor to development of a positioning readiness scale. In addition, a structural equation model is proposed to assess the overall and component-based effects of using the elements in the checklist on achieving strong market positions
Self-interaction errors in density functional calculations of electronic transport
All density functional calculations of single-molecule transport to date have
used continuous exchange-correlation approximations. The lack of derivative
discontinuity in such calculations leads to the erroneous prediction of
metallic transport for insulating molecules. A simple and computationally
undemanding atomic self-interaction correction greatly improves the agreement
with experiment for the prototype Au/dithiolated-benzene/Au junction.Comment: 4 pages. Also available at http://www.smeagol.tcd.i
The ultrafilter number for singular cardinals
We prove the consistency of a singular cardinal with small value of
the ultrafilter number , and arbitrarily large value of .Comment: 8 page
Average and worst-case specifications of precipitating auroral electron environment
The precipitation electrons in the auroral environment are highly variable in their energy and intensity in both space and time. As such they are a source of potential hazard to the operation of the Space Shuttle and other large spacecraft operating in polar orbit. In order to assess these hazards both the average and extreme states of the precipitating electrons must be determined. Work aimed at such a specification is presented. First results of a global study of the average characteristics are presented. In this study the high latitude region was divided into spatial elements in magnetic local time and corrected geomagnetic latitude. The average electron spectrum was then determined in each spatial element for seven different levels of activity as measured by K sub p using an extremely large data set of auroral observations. Second a case study of an extreme auroral electron environment is presented, in which the electrons are accelerated through field aligned potential as high as 30,000 volts and in which the spacecraft is seen to charge negatively to a potential approaching .5 kilovolts
The value of mobile tablet computers (iPads) in the undergraduate medical curriculum
The deployment of mobile tablet computers in medical teaching and learning is viewed with mounting interest. Medical educators are embracing insights from technological advancements to ensure that students are equipped with the necessary tools to flourish as physicians. Here we reflect on the benefits and challenges of the tablet learning experience within undergraduate medicine and how students may make the best use of it
Scanning tunneling spectroscopy of superconducting LiFeAs single crystals: Evidence for two nodeless energy gaps and coupling to a bosonic mode
The superconducting compound, LiFeAs, is studied by scanning tunneling
microscopy and spectroscopy. A gap map of the unreconstructed surface indicates
a high degree of homogeneity in this system. Spectra at 2 K show two nodeless
superconducting gaps with meV and
meV. The gaps close as the temperature is increased to the bulk
indicating that the surface accurately represents the bulk. A dip-hump
structure is observed below with an energy scale consistent with a
magnetic resonance recently reported by inelastic neutron scattering
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