6,811 research outputs found
Analytical studies of in-reactor tests of a nuclear light bulb unit cell
Analytical studies of in-reactor tests of nuclear light bulb unit cell using Pewee, nuclear furnace, and high flux isotope reactor
Analytical studies of nuclear light bulb engine radiant heat transfer and performance characteristics
Analytical model of nuclear light bulb engine radiant heat transfer and engine performance, dynamics and control, heat loads and shutdown characteristic
Studies of nuclear light bulb start-up conditions and engine dynamics
Deep Space Network for two-way communications with unmanned spacecraft at planetary distances - Vol.
Observation of the rare decay B+ -> K+π0π0 and measurement of the quasi-two-body contributions B+ -> K*(892)+π0, B+ -> f0(980)K+, and B+ -> χc0K+
We report an analysis of charmless hadronic decays of charged B mesons to the final state K(+) pi(0)pi(0), using a data sample of (470.9 +/- 2.8) x 10(6) B (B) over bar events collected with the BABAR detector at the Y(4S) resonance. We observe an excess of signal events, with a significance above 10 standard deviations including systematic uncertainties, and measure the branching fraction and CP asymmetry to be B(B(+) -> K(+) pi(0)pi(0)) = (16.2 +/- 1.2 +/- 1.5) x 10(-6) and A(CP)(B(+) -> K(+) pi(0)pi(0)) = -0.06 +/- 0.06 +/- 0.04, where the uncertainties are statistical and systematic, respectively. Additionally, we study the contributions of the B(+) -> K*(892)(+) pi(0), B(+) -> f(0)(980)K(+), and B(+) -> chi(c0)K(+) quasi-two-body decays. We report the world's best measurements of the branching fraction and CP asymmetry of the B(+) -> K(+) pi(0)pi(0) and B(+) -> K(+)(892)(+) pi(0) channels
Is cytotoxic chemotherapy for lymphoma currently feasible for patients in Malawi? A debate
There is currently no systematic provision for chemotherapy of adult patients with cancer in Malawi. Is the introduction of such a service now feasible in Malawi, and should an individual patient with potentially treatable disease be given chemotherapy in the absence of such a service? The technical, economic and moral issues are discussed here in the form of a debate.Malawi Medical Journal Vol. 20 (4) 2008: pp. 120-12
Sparse connectivity for MAP inference in linear models using sister mitral cells
Sensory processing is hard because the variables of interest are encoded in spike trains in a relatively complex way. A major goal in studies of sensory processing is to understand how the brain extracts those variables. Here we revisit a common encoding model in which variables are encoded linearly. Although there are typically more variables than neurons, this problem is still solvable because only a small number of variables appear at any one time (sparse prior). However, previous solutions require all-to-all connectivity, inconsistent with the sparse connectivity seen in the brain. Here we propose an algorithm that provably reaches the MAP (maximum a posteriori) inference solution, but does so using sparse connectivity. Our algorithm is inspired by the circuit of the mouse olfactory bulb, but our approach is general enough to apply to other modalities. In addition, it should be possible to extend it to nonlinear encoding models
Shared Information -- New Insights and Problems in Decomposing Information in Complex Systems
How can the information that a set of random variables
contains about another random variable be decomposed? To what extent do
different subgroups provide the same, i.e. shared or redundant, information,
carry unique information or interact for the emergence of synergistic
information?
Recently Williams and Beer proposed such a decomposition based on natural
properties for shared information. While these properties fix the structure of
the decomposition, they do not uniquely specify the values of the different
terms. Therefore, we investigate additional properties such as strong symmetry
and left monotonicity. We find that strong symmetry is incompatible with the
properties proposed by Williams and Beer. Although left monotonicity is a very
natural property for an information measure it is not fulfilled by any of the
proposed measures.
We also study a geometric framework for information decompositions and ask
whether it is possible to represent shared information by a family of posterior
distributions.
Finally, we draw connections to the notions of shared knowledge and common
knowledge in game theory. While many people believe that independent variables
cannot share information, we show that in game theory independent agents can
have shared knowledge, but not common knowledge. We conclude that intuition and
heuristic arguments do not suffice when arguing about information.Comment: 20 page
Analytical studies of start-up and dynamic response characteristics of the nuclear light bulb engine
Computerized simulation of control systems for nuclear light bulb engine during start-up and at nominal full power operatio
Discovery and Characterization of Transiting SuperEarths Using an All-Sky Transit Survey and Follow-up by the James Webb Space Telescope
Doppler and transit surveys are finding extrasolar planets of ever smaller
mass and radius, and are now sampling the domain of superEarths (1-3 Earth
radii). Recent results from the Doppler surveys suggest that discovery of a
transiting superEarth in the habitable zone of a lower main sequence star may
be possible. We evaluate the prospects for an all-sky transit survey targeted
to the brightest stars, that would find the most favorable cases for
photometric and spectroscopic characterization using the James Webb Space
Telescope (JWST). We use the proposed Transiting Exoplanet Survey Satellite
(TESS) as representative of an all-sky survey. We couple the simulated TESS
yield to a sensitivity model for the MIRI and NIRSpec instruments on JWST. We
focus on the TESS planets with radii between Earth and Neptune. Our simulations
consider secondary eclipse filter photometry using JWST/MIRI, comparing the 11-
and 15-micron bands to measure CO2 absorption in superEarths, as well as
JWST/NIRSpec spectroscopy of water absorption from 1.7-3.0 microns, and CO2
absorption at 4.3-microns. We project that TESS will discover about eight
nearby habitable transiting superEarths. The principal sources of uncertainty
in the prospects for JWST characterization of habitable superEarths are
superEarth frequency and the nature of superEarth atmospheres. Based on our
estimates of these uncertainties, we project that JWST will be able to measure
the temperature, and identify molecular absorptions (water, CO2) in one to four
nearby habitable TESS superEarths.Comment: accepted for PASP; added discussion and figure for habitable planets;
abridged Abstrac
The Transit Light Curve Project. VI. Three Transits of the Exoplanet TrES-2
Of the nearby transiting exoplanets that are amenable to detailed study,
TrES-2 is both the most massive and has the largest impact parameter. We
present z-band photometry of three transits of TrES-2. We improve upon the
estimates of the planetary, stellar, and orbital parameters, in conjunction
with the spectroscopic analysis of the host star by Sozzetti and co-workers. We
find the planetary radius to be 1.222 +/- 0.038 R_Jup and the stellar radius to
be 1.003 +/- 0.027 R_Sun. The quoted uncertainties include the systematic error
due to the uncertainty in the stellar mass (0.980 +/- 0.062 M_Sun). The timings
of the transits have an accuracy of 25s and are consistent with a uniform
period, thus providing a baseline for future observations with the NASA Kepler
satellite, whose field of view will include TrES-2.Comment: 15 pages, including 2 figures, accepted Ap
- …