21,202 research outputs found
Influence of correlated visual cues on auditory signal detection
Influence of correlated visual cues on auditory signal detectio
The geometrically-averaged density of states as a measure of localization
Motivated by current interest in disordered systems of interacting electrons,
the effectiveness of the geometrically averaged density of states,
, as an order parameter for the Anderson transition is
examined. In the context of finite-size systems we examine complications which
arise from finite energy resolution. Furthermore we demonstrate that even in
infinite systems a decline in with increasing disorder
strength is not uniquely associated with localization.Comment: 8 pages, 8 figures; revised text and figure
Budget Feasible Mechanisms for Experimental Design
In the classical experimental design setting, an experimenter E has access to
a population of potential experiment subjects , each
associated with a vector of features . Conducting an experiment
with subject reveals an unknown value to E. E typically assumes
some hypothetical relationship between 's and 's, e.g., , and estimates from experiments, e.g., through linear
regression. As a proxy for various practical constraints, E may select only a
subset of subjects on which to conduct the experiment.
We initiate the study of budgeted mechanisms for experimental design. In this
setting, E has a budget . Each subject declares an associated cost to be part of the experiment, and must be paid at least her cost. In
particular, the Experimental Design Problem (EDP) is to find a set of
subjects for the experiment that maximizes V(S) = \log\det(I_d+\sum_{i\in
S}x_i\T{x_i}) under the constraint ; our objective
function corresponds to the information gain in parameter that is
learned through linear regression methods, and is related to the so-called
-optimality criterion. Further, the subjects are strategic and may lie about
their costs.
We present a deterministic, polynomial time, budget feasible mechanism
scheme, that is approximately truthful and yields a constant factor
approximation to EDP. In particular, for any small and , we can construct a (12.98, )-approximate mechanism that is
-truthful and runs in polynomial time in both and
. We also establish that no truthful,
budget-feasible algorithms is possible within a factor 2 approximation, and
show how to generalize our approach to a wide class of learning problems,
beyond linear regression
Digital computer processing of LANDSAT data for North Alabama
Computer processing procedures and programs applied to Multispectral Scanner data from LANDSAT are described. The output product produced is a level 1 land use map in conformance with a Universal Transverse Mercator projection. The region studied was a five-county area in north Alabama
Employment may protect fathers in the setting of maternal teenage pregnancy from anxiety and depression: Findings from the Australian Father\u27s Study
Objective: There is limited research on fathers in the setting of maternal teenage pregnancy. Most studies report data from regions of social disadvantage and low education. We report on the levels of anxiety, depression and quality of life of fathers in the setting of maternal teenage pregnancy in an area where the unemployment rate is low.
Methods: Observational study of 50 fathers in the setting of maternal teenage pregnancy and 100 fathers whose partners were not teenagers (control), living within the same metropolitan healthcare region with high employment rates. Fathers were enrolled within the larger Australian Father’s Study and were recruited from antenatal clinics and community settings. Researchers administered the Hospital Anxiety and Depression Scale, Satisfaction with Life Scale and demographic questionnaires.
Results: Fathers in the setting of maternal teenage pregnancy were significantly younger than control fathers (p\u3c0.05). After adjusting for demographic variables, fathers in the setting of maternal teenage pregnancy did not have levels of anxiety, depression or quality of life that were significantly different to control fathers.
Conclusion: Fathers in the setting of maternal teenage pregnancy, when engaged in further education or employment have levels of anxiety, depression and quality of life comparable to control fathers
Electrometry using the quantum Hall effect in a bilayer 2D electron system
We discuss the development of a sensitive electrometer that utilizes a
two-dimensional electron gas (2DEG) in the quantum Hall regime. As a
demonstration, we measure the evolution of the Landau levels in a second,
nearby 2DEG as the applied perpendicular magnetic field is changed, and extract
an effective mass for electrons in GaAs that agrees within experimental error
with previous measurements.Comment: 3.5 pages, 3 figures, submitted to APL
Deep Space Network information system architecture study
The purpose of this article is to describe an architecture for the Deep Space Network (DSN) information system in the years 2000-2010 and to provide guidelines for its evolution during the 1990s. The study scope is defined to be from the front-end areas at the antennas to the end users (spacecraft teams, principal investigators, archival storage systems, and non-NASA partners). The architectural vision provides guidance for major DSN implementation efforts during the next decade. A strong motivation for the study is an expected dramatic improvement in information-systems technologies, such as the following: computer processing, automation technology (including knowledge-based systems), networking and data transport, software and hardware engineering, and human-interface technology. The proposed Ground Information System has the following major features: unified architecture from the front-end area to the end user; open-systems standards to achieve interoperability; DSN production of level 0 data; delivery of level 0 data from the Deep Space Communications Complex, if desired; dedicated telemetry processors for each receiver; security against unauthorized access and errors; and highly automated monitor and control
Origin of the hysteresis in bilayer 2D systems in the quantum Hall regime
The hysteresis observed in the magnetoresistance of bilayer 2D systems in the
quantum Hall regime is generally attributed to the long time constant for
charge transfer between the 2D systems due to the very low conductivity of the
quantum Hall bulk states. We report electrometry measurements of a bilayer 2D
system that demonstrate that the hysteresis is instead due to non-equilibrium
induced current. This finding is consistent with magnetometry and electrometry
measurements of single 2D systems, and has important ramifications for
understanding hysteresis in bilayer 2D systems.Comment: 4 pages, 3 figs. Accepted for publication in PR
Effect of Proximity Coupling of Chains and Planes on the Penetration Depth Anisotropy in Y_1Ba_2Cu_3O_7
We calculate the penetration depth in the , and
directions for a simple model of YBaCuO. In this model there are
two layers---representing a CuO plane and a CuO chain---per unit cell.
There is a BCS--like pairing (both wave and wave are considered)
interaction localised in the CuO planes. The CuO chains become
superconducting at temperatures lower than because of their proximity to
the planes, and there is an induced gap in the chains. Since the temperature
dependence of the penetration depth in the direction (along the chains) is
sensitive to the size of the induced gap, the difference between the shapes of
the penetration depth curves in the and directions reveals a great deal
about the nature of the condensate in the chains. We find that in our proximity
model there are always regions of the chain Fermi surface on which the induced
gap is much smaller than , so that the temperature dependence of
is always different than that of . Experimental
observations of the of the anisotropy show nearly identical temperature
dependences. The main result of our paper, then, is that a simple proximity
model in which the pairing interaction is localized to the planes, and the
planes are coherently coupled to the chains cannot account for the superfluid
on the chains.Comment: 24 Pages, Submitted to Phys. Rev.
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