5,649 research outputs found
Scales for co-compact embeddings of virtually free groups
Let be a group which is virtually free of rank at least 2 and let
be the family of totally disconnected, locally
compact groups containing as a co-compact lattice.
We prove that the values of the scale function with respect to groups in
evaluated on the subset have only finitely
many prime divisors. This can be thought of as a uniform property of the family
.Comment: 12 pages; key words: uniform lattice, virtually free group, totally
disconnected group, scale function (Error in references corrected in version
2
Effects of Neutron Irradiation on Pinning Force Scaling in State-of-the-Art Nb3Sn Wires
We present an extensive irradiation study involving five state-of-the-art
Nb3Sn wires which were subjected to sequential neutron irradiation up to a fast
neutron fluence of 1.6 * 10^22 m^-2 (E > 0.1 MeV). The volume pinning force of
short wire samples was assessed in the temperature range from 4.2 to 15 K in
applied fields of up to 7 T by means of SQUID magnetometry in the unirradiated
state and after each irradiation step. Pinning force scaling computations
revealed that the exponents in the pinning force function differ significantly
from those expected for pure grain boundary pinning, and that fast neutron
irradiation causes a substantial change in the functional dependence of the
volume pinning force. A model is presented, which describes the pinning force
function of irradiated wires using a two-component ansatz involving a
point-pinning contribution stemming from radiation induced pinning centers. The
dependence of this point-pinning contribution on fast neutron fluence appears
to be a universal function for all examined wire types.Comment: 8 page
Optical imaging of resonant electrical carrier injection into individual quantum dots
We image the micro-electroluminescence (EL) spectra of self-assembled InAs
quantum dots (QDs) embedded in the intrinsic region of a GaAs p-i-n diode and
demonstrate optical detection of resonant carrier injection into a single QD.
Resonant tunneling of electrons and holes into the QDs at bias voltages below
the flat-band condition leads to sharp EL lines characteristic of individual
QDs, accompanied by a spatial fragmentation of the surface EL emission into
small and discrete light- emitting areas, each with its own spectral
fingerprint and Stark shift. We explain this behavior in terms of Coulomb
interaction effects and the selective excitation of a small number of QDs
within the ensemble due to preferential resonant tunneling paths for carriers.Comment: 4 page
ResolanaPaving Paths Toward Transformation with Incarcerated Women
The purpose of this study was to elicit the experiences of women who participated in a gender-responsive program in jail. Results indicate the holistic programming and learning environment was an emancipatory container where transformation could occur through interpersonal and intrapersonal engagement. Findings have implications for the education of incarcerated women
Educators’ Reflections on Empowerment in a Gender Responsive Program for Women Offenders
We explore women educators’ experiences teaching in a gender-responsive program for women who are incarcerated. Themes including fostering empowerment, motivations for teaching, and tensions teaching emancipatory content in jail
Measuring cosmological bulk flows via the kinematic Sunyaev-Zeldovich effect in the upcoming cosmic microwave background maps
We propose a new method to measure the possible large-scale bulk flows in the
Universe from the cosmic microwave background (CMB) maps from the upcoming
missions, MAP and Planck. This can be done by studying the statistical
properties of the CMB temperature field at many X-ray cluster positions. At
each cluster position, the CMB temperature fluctuation will be a combination of
the Sunyaev-Zeldovich (SZ) kinematic and thermal components, the cosmological
fluctuations and the instrument noise term. When averaged over many such
clusters the last three will integrate down, whereas the first one will be
dominated by a possible bulk flow component. In particular, we propose to use
all-sky X-ray cluster catalogs that should (or could) be available soon from
X-ray satellites, and then to evaluate the dipole component of the CMB field at
the cluster positions. We show that for the MAP and Planck mission parameters
the dominant contributions to the dipole will be from the terms due to the SZ
kinematic effect produced by the bulk flow (the signal we seek) and the
instrument noise (the noise in our signal). Computing then the expected
signal-to-noise ratio for such measurement, we get that at the 95 % confidence
level the bulk flows on scales >100h^{-1} Mpc can be probed down to the
amplitude of km/sec with the MAP data and down to only 30 km/sec with
the Planck mission.Comment: Astrophysical Journal Letters, in pres
Large time dynamics and aging of a polymer chain in a random potential
We study the out-of-equilibrium large time dynamics of a gaussian polymer
chain in a quenched random potential. The dynamics studied is a simple Langevin
dynamics commonly referred to as the Rouse model. The equations for the
two-time correlation and response function are derived within the gaussian
variational approximation. In order to implement this approximation faithfully,
we employ the supersymmetric representation of the Martin-Siggia-Rose dynamical
action. For a short ranged correlated random potential the equations are solved
analytically in the limit of large times using certain assumptions concerning
the asymptotic behavior. Two possible dynamical behaviors are identified
depending upon the time separation- a stationary regime and an aging regime. In
the stationary regime time translation invariance holds and so is the
fluctuation dissipation theorem. The aging regime which occurs for large time
separations of the two-time correlation functions is characterized by history
dependence and the breakdown of certain equilibrium relations. The large time
limit of the equations yields equations among the order parameters that are
similar to the equations obtained in the statics using replicas. In particular
the aging solution corresponds to the broken replica solution. But there is a
difference in one equation that leads to important consequences for the
solution. The stationary regime corresponds to the motion of the polymer inside
a local minimum of the random potential, whereas in the aging regime the
polymer hops between different minima. As a byproduct we also solve exactly the
dynamics of a chain in a random potential with quadratic correlations.Comment: 21 pages, RevTeX
Decidability of the Monadic Shallow Linear First-Order Fragment with Straight Dismatching Constraints
The monadic shallow linear Horn fragment is well-known to be decidable and
has many application, e.g., in security protocol analysis, tree automata, or
abstraction refinement. It was a long standing open problem how to extend the
fragment to the non-Horn case, preserving decidability, that would, e.g.,
enable to express non-determinism in protocols. We prove decidability of the
non-Horn monadic shallow linear fragment via ordered resolution further
extended with dismatching constraints and discuss some applications of the new
decidable fragment.Comment: 29 pages, long version of CADE-26 pape
Stable isotopic disequilibrium in high-T metamorphic systems
A principal use of stable isotopes in metamorphic rocks is as thermometers, or as tests for isotopic equilibrium
where metamorphic temperatures are known. Applications are often complicated when apparent isotopic
temperatures are discordant and disagree with petrologic temperatures, indicating a failure of isotopic systems
to record and/or preserve equilibrium, peak-T fractionations. In low-T, fluid-hosted environments such features
often clearly reflect open system exchange. However, in high-T metamorphic environments a slow cooling
history can be sufficient to produce such features by retrograde, closed system exchange between coexisting
minerals
- …