6,468 research outputs found
Causal connectivity of evolved neural networks during behavior
To show how causal interactions in neural dynamics are modulated by behavior, it is valuable to analyze these interactions without perturbing or lesioning the neural mechanism. This paper proposes a method, based on a graph-theoretic extension of vector autoregressive modeling and 'Granger causality,' for characterizing causal interactions generated within intact neural mechanisms. This method, called 'causal connectivity analysis' is illustrated via model neural networks optimized for controlling target fixation in a simulated head-eye system, in which the structure of the environment can be experimentally varied. Causal connectivity analysis of this model yields novel insights into neural mechanisms underlying sensorimotor coordination. In contrast to networks supporting comparatively simple behavior, networks supporting rich adaptive behavior show a higher density of causal interactions, as well as a stronger causal flow from sensory inputs to motor outputs. They also show different arrangements of 'causal sources' and 'causal sinks': nodes that differentially affect, or are affected by, the remainder of the network. Finally, analysis of causal connectivity can predict the functional consequences of network lesions. These results suggest that causal connectivity analysis may have useful applications in the analysis of neural dynamics
Summary of Experimental Meson Physics
A summary of the present experimental status of meson physics is presented.
The presentation includes the new results presented at the MESON06 workshop, as
well as other recent experimental developments in the field.Comment: 15 pages, 6 figures, presented at 9th International Workshop on Meson
Production, Properties and Interaction, Krakow, Poland, June 200
A Comprehensive Study of the Radiative Decays of and to Pseudoscalar Meson Pairs, and Search for Glueballs
Using 53 pb of annihilation data taken at
GeV, a comprehensive study has been made of the radiative decays of samples of
5.1 million and 24.5 million into pairs of pseudoscalar
mesons, , , , , and .
Product branching fractions for the radiative decays of and
to scalar resonances , and tensor
resonances have been determined, and are
discussed in relation to predicted glueballs. For radiative decays
the search for glueballs has been extended to masses between 2.5 GeV and 3.3
GeV.Comment: 21 pages, 14 figures, published in PR
Quantum Pumping with Ultracold Atoms on Microchips: Fermions versus Bosons
We present a design for simulating quantum pumping of electrons in a
mesoscopic circuit with ultra-cold atoms in a micro-magnetic chip trap. We
calculate theoretical results for quantum pumping of both bosons and fermions,
identifying differences and common features, including geometric behavior and
resonance transmission. We analyze the feasibility of experiments with bosonic
Rb and fermionic K atoms with an emphasis on reliable atomic
current measurements.Comment: 4 pages; 4 figure
Recommended from our members
State-Level and County-Level Estimates of Health Care Costs Associated with Food Insecurity.
IntroductionFood insecurity, or uncertain access to food because of limited financial resources, is associated with higher health care expenditures. However, both food insecurity prevalence and health care spending vary widely in the United States. To inform public policy, we estimated state-level and county-level health care expenditures associated with food insecurity.MethodsWe used linked 2011-2013 National Health Interview Survey/Medical Expenditure Panel Survey data (NHIS/MEPS) data to estimate average health care costs associated with food insecurity, Map the Meal Gap data to estimate state-level and county-level food insecurity prevalence (current though 2016), and Dartmouth Atlas of Health Care data to account for local variation in health care prices and intensity of use. We used targeted maximum likelihood estimation to estimate health care costs associated with food insecurity, separately for adults and children, adjusting for sociodemographic characteristics.ResultsAmong NHIS/MEPS participants, 10,054 adults and 3,871 children met inclusion criteria. Model estimates indicated that food insecure adults had annual health care expenditures that were 1,073-2,595, P < .001) higher than food secure adults. For children, estimates were 80 higher, but this finding was not significant (95% CI, -329, P = .53). The median annual health care cost associated with food insecurity was 239,675,000; 75th percentile, 4,433,000 (25th percentile, 11,267,000). Cost variability was related primarily to food insecurity prevalence.ConclusionsHealth care expenditures associated with food insecurity vary substantially across states and counties. Food insecurity policies may be important mechanisms to contain health care expenditures
New Results From CLEO and BES
Latest experimental results from BES in the charmonium mass region, and those
from CLEO in the bottomonium and charmonium spectroscopy are reviewed.Comment: 12 pages, 12 figures, Presented at First Meeting of the APS Topical
Group on Hadron Physics, Fermilab, Batavia, Illinois, Oct 24-26, 200
Light Quark Resonances in pbar p Annihilations at 5.2 GeV/c
Data from the Fermilab E835 experiment have been used to study the reaction
pbar p -> eta eta pi0 at 5.2 GeV/c. A sample of 22 million six photons events
has been analyzed to construct the Dalitz plot containing ~80k eta eta pi0
events. A partial wave analysis of the data has been done. Six f_J-states
decaying into eta eta and five a_J-states decaying into eta pi0 are identified
in the mass region ~1.3 and 2.4 GeV, and their masses, widths and spins are
determined by maximum likelihood analysis of the data. Two f_0 states are
identified with the popular candidates for the lightest scalar glueball,
f_0(1500) and f_0(1710).Comment: 7 pages, 6 figure
Generation and detection of NOON states in superconducting circuits
NOON states, states between two modes of light of the form
allow for super-resolution interformetry. We
show how NOON states can be efficiently produced in circuit quntum
electrodynamics using superconducting phase qubits and resonators. We propose a
protocol where only one interaction between the two modes is required, creating
all the necessary entanglement at the start of the procedure. This protocol
makes active use of the first three states of the phase qubits. Additionally,
we show how to efficiently verify the success of such an experiment, even for
large NOON states, using randomly sampled measurements and semidefinite
programming techniques.Comment: 15 pages and 3 figure
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