5,019 research outputs found
Educational planning for utilization of space shuttle (ED-PLUSS). Executive summary: Identification and evaluation of educational uses and users for the STS
The development and application of educational programs to improve public awareness of the space shuttle/space lab capabilities are reported. Special efforts were made to: identify the potential user, identify and analyze space education programs, plan methods for user involvement, develop techniques and programs to encourage new users, and compile follow-on ideas
Identification and evaluation of educational uses and users for the STS. Educational planning for utilization of space shuttle ED-PLUSS
A planning and feasibility study to identify and document a methodology needed to incorporate educational programs into future missions and operations of the space transportation system was conducted. Six tasks were identified and accomplished during the study. The task statements are as follows: (1) potential user identification, (2) a review of space education programs, (3) development of methodology for user involvement, (4) methods to encourage user awareness, (5) compilation of follow-on ideas, and (6) response to NASA questions. Specific recommendations for improving the educational coverage of space activities are provided
One vertex spin-foams with the Dipole Cosmology boundary
We find all the spin-foams contributing in the first order of the vertex
expansion to the transition amplitude of the Bianchi-Rovelli-Vidotto Dipole
Cosmology model. Our algorithm is general and provides spin-foams of
arbitrarily given, fixed: boundary and, respectively, a number of internal
vertices. We use the recently introduced Operator Spin-Network Diagrams
framework.Comment: 23 pages, 30 figure
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Strategies to achieve adequate vitamin A intake for young children: options for Cameroon.
Meeting children's vitamin A (VA) needs remains a policy priority. Doing so efficiently is a fiscal imperative and protecting at-risk children during policy transitions is a moral imperative. Using the Micronutrient Intervention Modeling tool and data for Cameroon, we predict the impacts and costs of alternative VA intervention programs, identify the least-cost strategy for meeting targets nationally, and compare it to a business-as-usual (BAU) strategy over 10 years. BAU programs effectively cover ∼12.8 million (m) child-years (CY) and cost ∼2.34 per CY effectively covered. Improving the VA-fortified oil program, implementing a VA-fortified bouillon cube program, and periodic VA supplements (VAS) in the North macroregion for 3 years effectively cover ∼13.1 m CY at a cost of ∼US0.71 per CY effectively covered. The tool then identifies a sequence of subnational policy choices leading from the BAU toward the more efficient strategy, while addressing VA-attributable mortality concerns. By year 4, fortification programs are predicted to eliminate inadequate VA intake in the South and Cities macroregions, but not the North, where VAS should continue until additional delivery platforms are implemented. This modeling approach offers a concrete example of the strategic use of data to follow the Global Alliance for VA framework and do so efficiently
Value at Risk models with long memory features and their economic performance
We study alternative dynamics for Value at Risk (VaR) that incorporate a slow moving component and information on recent aggregate returns in established quantile (auto) regression models. These models are compared on their economic performance, and also on metrics of first-order importance such as violation ratios. By better economic performance, we mean that changes in the VaR forecasts should have a lower variance to reduce transaction costs and should lead to lower exceedance sizes without raising the average level of the VaR. We find that, in combination with a targeted estimation strategy, our proposed models lead to improved performance in both statistical and economic terms
Multipole Moments of Isolated Horizons
To every axi-symmetric isolated horizon we associate two sets of numbers,
and with , representing its mass and angular
momentum multipoles. They provide a diffeomorphism invariant characterization
of the horizon geometry. Physically, they can be thought of as the `source
multipoles' of black holes in equilibrium. These structures have a variety of
potential applications ranging from equations of motion of black holes and
numerical relativity to quantum gravity.Comment: 25 pages, 1 figure. Minor typos corrected, reference adde
Artificial Intelligence Approach to the Determination of Physical Properties of Eclipsing Binaries. I. The EBAI Project
Achieving maximum scientific results from the overwhelming volume of
astronomical data to be acquired over the next few decades will demand novel,
fully automatic methods of data analysis. Artificial intelligence approaches
hold great promise in contributing to this goal. Here we apply neural network
learning technology to the specific domain of eclipsing binary (EB) stars, of
which only some hundreds have been rigorously analyzed, but whose numbers will
reach millions in a decade. Well-analyzed EBs are a prime source of
astrophysical information whose growth rate is at present limited by the need
for human interaction with each EB data-set, principally in determining a
starting solution for subsequent rigorous analysis. We describe the artificial
neural network (ANN) approach which is able to surmount this human bottleneck
and permit EB-based astrophysical information to keep pace with future data
rates. The ANN, following training on a sample of 33,235 model light curves,
outputs a set of approximate model parameters (T2/T1, (R1+R2)/a, e sin(omega),
e cos(omega), and sin i) for each input light curve data-set. The whole sample
is processed in just a few seconds on a single 2GHz CPU. The obtained
parameters can then be readily passed to sophisticated modeling engines. We
also describe a novel method polyfit for pre-processing observational light
curves before inputting their data to the ANN and present the results and
analysis of testing the approach on synthetic data and on real data including
fifty binaries from the Catalog and Atlas of Eclipsing Binaries (CALEB)
database and 2580 light curves from OGLE survey data. [abridged]Comment: 52 pages, accepted to Ap
Colored Group Field Theory
Group field theories are higher dimensional generalizations of matrix models.
Their Feynman graphs are fat and in addition to vertices, edges and faces, they
also contain higher dimensional cells, called bubbles. In this paper, we
propose a new, fermionic Group Field Theory, posessing a color symmetry, and
take the first steps in a systematic study of the topological properties of its
graphs. Unlike its bosonic counterpart, the bubbles of the Feynman graphs of
this theory are well defined and readily identified. We prove that this graphs
are combinatorial cellular complexes. We define and study the cellular homology
of this graphs. Furthermore we define a homotopy transformation appropriate to
this graphs. Finally, the amplitude of the Feynman graphs is shown to be
related to the fundamental group of the cellular complex
Motion in Quantum Gravity
We tackle the question of motion in Quantum Gravity: what does motion mean at
the Planck scale? Although we are still far from a complete answer we consider
here a toy model in which the problem can be formulated and resolved precisely.
The setting of the toy model is three dimensional Euclidean gravity. Before
studying the model in detail, we argue that Loop Quantum Gravity may provide a
very useful approach when discussing the question of motion in Quantum Gravity.Comment: 30 pages, to appear in the book "Mass and Motion in General
Relativity", proceedings of the C.N.R.S. School in Orleans, France, eds. L.
Blanchet, A. Spallicci and B. Whitin
The SU(2) black hole entropy revisited
We study the state-counting problem that arises in the SU(2) black hole entropy calculation in loop quantum gravity. More precisely, we compute the leading term and the logarithmic correction of both the spherically symmetric and the distorted SU( 2) black holes. Contrary to what has been done in previous works, we have to take into account "quantum corrections" in our framework in the sense that the level k of the Chern-Simons theory which describes the black hole is finite and not sent to infinity. Therefore, the new results presented here allow for the computation of the entropy in models where the quantum group corrections are important
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