10,342 research outputs found
Why a Catholic Medical School?
Editor\u27s Note: In October 1963, for the observance of Founders Day at St. Louis University, the School of Medicine participated in a panel on the objectives of Catholic medical education. The papers of Reverend E.J. Drummond, S.J., C. Rollins Hanlon, M.D., John V. King, M.D., and Edward T. Auer, M.D. are presented here
Comparison of Low Earth Orbit and Geosynchronous Earth Orbits
The technological, environmental, social, and political ramifications of low Earth orbits as compared to geosynchronous Earth orbits for the solar power satellite (SPS) are assessed. The capital cost of the transmitting facilities is dependent on the areas of the antenna and rectenna relative to the requirement of high efficiency power transmission. The salient features of a low orbit Earth orbits are discussed in terms of cost reduction efforts
Superstring amplitudes and the associator
We investigate a pattern in the expansion of tree-level open
superstring amplitudes which correlates the appearance of higher depth multiple
zeta values with that of simple zeta values in a particular way. We rephrase
this relationship in terms of the coaction on motivic multiple zeta values and
show that the pattern takes a very simple form, which can be simply explained
by relating the amplitudes to the Drinfel'd associator derived from the
Knizhnik-Zamolodchikov equation. Given this correspondence we show that, at
least in the simplest case of the four-point amplitude, the associator can be
used to extract the form of the amplitude.Comment: 20 pages, 1 figur
Pyrheliometric comparisons at the JPL Table Mountain Facility
Calibration and comparative measurements of pyrheliometric instruments using natural sunligh
Quantum Monte Carlo Calculation of the Binding Energy of Bilayer Graphene
We report diffusion quantum Monte Carlo calculations of the interlayer
binding energy of bilayer graphene. We find the binding energies of the AA- and
AB-stacked structures at the equilibrium separation to be 11.5(9) and 17.7(9)
meV/atom, respectively. The out-of-plane zone-center optical phonon frequency
predicted by our binding-energy curve is consistent with available experimental
results. As well as assisting the modeling of interactions between graphene
layers, our results will facilitate the development of van der Waals
exchange-correlation functionals for density functional theory calculations.Comment: 5 pages and 3 figures, submitted to Phys. Rev. Lett.; supplemental
material is available on arXiv via the ancillary files attached to this
submissio
Recommended from our members
Revisiting the one in four: the prevalence of psychiatric disorder in the population of England 2000-2014
Mental health problems are often said to affect one in four people in Britain, although with no consistent explanation of what the figure includes. We used three English national population surveys of psychiatric morbidity from 2000, 2007 and 2014 to provide prevalence rates for recent psychiatric problems. We combined disorders progressively to demonstrate the effects of cumulation. Psychosis had a prevalence of around 1%, severe common mental disorders added about 8%, and including less-severe common mental disorders gave a value around one in six. The figure of one in four required the inclusion of various other disorders. These values were strikingly stable over the surveys
Twistor transform of all tree amplitudes in N=4 SYM theory
We perform the twistor (half-Fourier) transform of all tree n-particle
superamplitudes in N=4 SYM and show that it has a transparent geometric
interpretation. We find that the N^kMHV amplitude is supported on a set of
(2k+1) intersecting lines in twistor space and demonstrate that the
corresponding line moduli form a lightlike (2k+1)-gon in moduli space. This
polygon is triangulated into two kinds of lightlike triangles lying in
different planes. We formulate simple graphical rules for constructing the
triangulated polygons, from which the analytic expressions of the N^kMHV
amplitudes follow directly, both in twistor and in momentum space. We also
discuss the ordinary and dual conformal properties and the cancellation of
spurious singularities in twistor space.Comment: 46 pages, 17 figure
Relating Superembeddings and Non-linear Realisations
We discuss the relation between the superembedding method for deriving
worldvolume actions for D-branes and the method of Partially Broken Global
Supersymmetry based upon linear and non-linear realisations of SUSY. We give
the explicit relation for the cases of space filling branes in 3 and 4
dimensions and show that the standard F-constraint of the superembedding method
is the source of the required covariant non-linear constraints for the PBGS
method.Comment: 19 pages. Improved spelling, references adde
The Yangian origin of the Grassmannian integral
In this paper we analyse formulas which reproduce different contributions to
scattering amplitudes in N=4 super Yang-Mills theory through a Grassmannian
integral. Recently their Yangian invariance has been proved directly by using
the explicit expression of the Yangian level-one generators. The specific
cyclic structure of the form integrated over the Grassmannian enters in a
crucial way in demonstrating the symmetry. Here we show that the Yangian
symmetry fixes this structure uniquely.Comment: 26 pages. v2: typos corrected, published versio
- …