1,485 research outputs found

### The Cutman

In this novel, professional wrestler Domingo Contreras coaches his sister, Pilar, on the eve of her tryout with Mid-Coast Championship Wrestling, a small federation based in Charlotte, North Carolina. While facing dilemmas concerning his identity inside and outside the ring, Domingo comes to realize that the business which is gradually destroying him will consume his sister at an even more terrifying rate

### The electronic structure of amorphous silica: A numerical study

We present a computational study of the electronic properties of amorphous
SiO2. The ionic configurations used are the ones generated by an earlier
molecular dynamics simulations in which the system was cooled with different
cooling rates from the liquid state to a glass, thus giving access to
glass-like configurations with different degrees of disorder [Phys. Rev. B 54,
15808 (1996)]. The electronic structure is described by a tight-binding
Hamiltonian. We study the influence of the degree of disorder on the density of
states, the localization properties, the optical absorption, the nature of
defects within the mobility gap, and on the fluctuations of the Madelung
potential, where the disorder manifests itself most prominently. The
experimentally observed mismatch between a photoconductivity threshold of 9 eV
and the onset of the optical absorption around 7 eV is interpreted by the
picture of eigenstates localized by potential energy fluctuations in a mobility
gap of approximately 9 eV and a density of states that exhibits valence and
conduction band tails which are, even in the absence of defects, deeply located
within the former band gap.Comment: 21 pages of Latex, 5 eps figure

### On the occurrence of Stenopus tenuirostris De Man, 1888 in Natal waters

The stenopodidean shrimp Stenopus tenuirostris De Man, 1888 is reported from Natal waters for the first time. This record represents a considerable southward extension of this uncommon tropical species for the African sub-region

### Functional Renormalization of Noncommutative Scalar Field Theory

In this paper we apply the Functional Renormalization Group Equation (FRGE)
to the non-commutative scalar field theory proposed by Grosse and Wulkenhaar.
We derive the flow equation in the matrix representation and discuss the theory
space for the self-dual model. The features introduced by the external
dimensionful scale provided by the non-commutativity parameter, originally
pointed out in \cite{Gurau:2009ni}, are discussed in the FRGE context. Using a
technical assumption, but without resorting to any truncation, it is then shown
that the theory is asymptotically safe for suitably small values of the
$\phi^4$ coupling, recovering the result of \cite{disertori:2007}. Finally, we
show how the FRGE can be easily used to compute the one loop beta-functions of
the duality covariant model.Comment: 38 pages, no figures, LaTe

### Cold Reactions of Alkali and Water Clusters inside Helium Nanodroplets

The reaction of alkali (Na, Cs) clusters with water clusters embedded in
helium nanodroplets is studied using femtosecond photo-ionization as well as
electron impact ionization. Unlike Na clusters, Cs clusters are found to
completely react with water in spite of the ultracold helium droplet
environment. Mass spectra of the Cs$_n$+(H$_2$O)$_m$ reaction products are
interpreted in terms of stability with respect to fragmentation using
high-level molecular structure calculations

### Singular kernels, multiscale decomposition of microstructure, and dislocation models

We consider a model for dislocations in crystals introduced by Koslowski,
Cuiti\~no and Ortiz, which includes elastic interactions via a singular kernel
behaving as the $H^{1/2}$ norm of the slip. We obtain a sharp-interface limit
of the model within the framework of $\Gamma$-convergence. From an analytical
point of view, our functional is a vector-valued generalization of the one
studied by Alberti, Bouchitt\'e and Seppecher to which their rearrangement
argument no longer applies. Instead we show that the microstructure must be
approximately one-dimensional on most length scales and exploit this property
to derive a sharp lower bound

### Empirical Corrections for Charge Transfer Inefficiency and Associated Centroid Shifts for STIS CCD Observations

A variety of on-orbit imaging and spectroscopic observations are used to
characterize the Charge Transfer Efficiency (CTE) of the Charge-Coupled Device
(CCD) of the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble
Space Telescope. A set of formulae is presented to correct observations of
point sources for CTE-related loss of signal. For data taken in imaging mode,
the CTE loss is parametrized in terms of the location of the source on the CCD,
the source signal level within the measurement aperture, the background level,
and the time of observation. For spectroscopic data, it is found that one
additional parameter is needed to provide an adequate calibration of the CTE
loss, namely the signal in the point spread function located between the signal
extraction box and the read-out amplifier. The effect of the latter parameter
is significant for spectra taken using the G750L or G750M gratings of STIS. The
algorithms presented here correct flux calibration inaccuracies due to CTE
losses as large as 30% to within ~ 1.5% RMS throughout the wavelength range
covered by the STIS CCD modes. This uncertainty is similar to the Poisson noise
associated with a source detected at a signal level of about 2500 electrons per
resolution element. Using bi-directional CCD readouts, centroid shifts incurred
due to CTE loss are also derived. A tight correlation is found between the CTE
loss and the centroid shift (both for imaging and spectroscopic modes), thus
enabling one to correct for both effects of imperfect charge transfer to STIS
CCD observations.Comment: 49 pages in AASTeX preprint format. 18 figures, 8 table

### Finite size effects and localization properties of disordered quantum wires with chiral symmetry

Finite size effects in the localization properties of disordered quantum
wires are analyzed through conductance calculations. Disorder is induced by
introducing vacancies at random positions in the wire and thus preserving the
chiral symmetry. For quasi one-dimensional geometries and low concentration of
vacancies, an exponential decay of the mean conductance with the wire length is
obtained even at the center of the energy band. For wide wires, finite size
effects cause the conductance to decay following a non-pure exponential law. We
propose an analytical formula for the mean conductance that reproduces
accurately the numerical data for both geometries. However, when the
concentration of vacancies increases above a critical value, a transition
towards the suppression of the conductance occurs.
This is a signature of the presence of ultra-localized states trapped in
finite regions of the sample.Comment: 5 figures, revtex

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