4,132 research outputs found
Metamodel-based model conformance and multiview consistency checking
Model-driven development, using languages such as UML and BON, often makes use of multiple diagrams (e.g., class and sequence diagrams) when modeling systems. These diagrams, presenting different views of a system of interest, may be inconsistent. A metamodel provides a unifying framework in which to ensure and check consistency, while at the same time providing the means to distinguish between valid and invalid models, that is, conformance. Two formal specifications of the metamodel for an object-oriented modeling language are presented, and it is shown how to use these specifications for model conformance and multiview consistency checking. Comparisons are made in terms of completeness and the level of automation each provide for checking multiview consistency and model conformance. The lessons learned from applying formal techniques to the problems of metamodeling, model conformance, and multiview consistency checking are summarized
Simulating Supersymmetry with ISAJET 7.0/ ISASUSY 1.0
We review the physics assumptions and input used in ISAJET~7.0 /
ISA\-SUSY~1.0 that are relevant for simulating fundamental processes within the
framework of the Minimal Supersymmetric Standard Model (MSSM) at and
colliders. After a brief discussion of the underlying MSSM framework, we
discuss event simulation and list the sparticle production processes and decay
modes that have been incorporated into our calculations. We then describe how
to set up and run an ISAJET / ISASUSY job and the user input and output
formats. The ISAJET program is sufficiently flexible that some non-minimal
supersymmetry scenarios may be simulated as well. Finally, plans for future
upgrades which include the extension to collisions, are listed.Comment: 17 pages, FSU-HEP-930329 UH-511-764-9
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Measurements in SUGRA Models with Large tan beta at LHC
We present an example of a scenario of particle production and decay in
supersymmetry models in which the supersymmetry breaking is transmitted to the
observable world via gravitational interactions. The case is chosen so that
there is a large production of tau leptons in the final state. It is
characteristic of large tan beta in that decays into muons and electrons may be
suppressed. It is shown that hadronic tau decays can be used to reconstruct
final states.Comment: 15 pages, 12 figure
Association Between Air Pollution and Low Birth Weight: A Community-Based Study
The relationship between maternal exposure to air pollution during periods of pregnancy (entire and specific periods) and birth weight was investigated in a well-defined cohort. Between 1988 and 1991, all pregnant women living in four residential areas of Beijing were registered and followed from early pregnancy until delivery. Information on individual mothers and infants was collected. Daily air pollution data were obtained independently. The sample for analysis included 74,671 first-parity live births were gestational age 37-44 weeks. Multiple linear regression and logistic regression were used to estimate the effects of air pollution on birth weight and low birth weight (< 2,500 g), adjusting for gestational age, residence, year of birth, maternal age, and infant gender. There was a significant exposure-response relationship between maternal exposures to sulfur dioxide (SO2) and total suspended particles (TSP) during the third trimester of pregnancy and infant birth weight. The adjusted odds ratio for low birth weight was 1.11 (95% CI, 1.06-1.16) for each 100 micrograms/m3 increase in SO2 and 1.10 (95% CI, 1.05-1.14) for each 100 micrograms/m3 increase in TSP. The estimated reduction in birth weight was 7.3 g and 6.9 g for each 100 micrograms/m3 increase in SO2 and in TSP, respectively. The birth weight distribution of the high-exposure group was more skewed toward the left tail (i.e., with higher proportion of births < 2,500 g) than that of the low-exposure group. Although the effects of other unmeasured risk factors cannot be excluded with certainty, our data suggests that TSP and SO2, or a more complex pollution mixture associated with these pollutants, contribute to an excess risk of low birth weight in the Beijing population.National Institute of Environmental Health Sciences (ES05947, ES08337); National Institute of Child Health & Human Development (R01 HD32505); Department of Health and Human Services (MCJ-259501, HRSA 5 T32 PE10014
Crop Planting Decisions for 2008 – An Initial Analysis
Prices tend to be the driving factor when considering which crops to plant and how many acres to plant. Deciding what to plant in 2008 could be even more complicated than this year, the decision being compounded by the fact that wheat is at record high price levels. To analyze breakeven prices for the three major commodities we can use crop budgets of expected costs
Mixed axion/neutralino cold dark matter in supersymmetric models
We consider supersymmetric (SUSY) models wherein the strong CP problem is
solved by the Peccei-Quinn (PQ) mechanism with a concommitant axion/axino
supermultiplet. We examine R-parity conserving models where the neutralino is
the lightest SUSY particle, so that a mixture of neutralinos and axions serve
as cold dark matter. The mixed axion/neutralino CDM scenario can match the
measured dark matter abundance for SUSY models which typically give too low a
value of the usual thermal neutralino abundance, such as models with wino-like
or higgsino-like dark matter. The usual thermal neutralino abundance can be
greatly enhanced by the decay of thermally-produced axinos to neutralinos,
followed by neutralino re-annihilation at temperatures much lower than
freeze-out. In this case, the relic density is usually neutralino dominated,
and goes as \sim (f_a/N)/m_{axino}^{3/2}. If axino decay occurs before
neutralino freeze-out, then instead the neutralino abundance can be augmented
by relic axions to match the measured abundance. Entropy production from
late-time axino decays can diminish the axion abundance, but ultimately not the
neutralino abundance. In mixed axion/neutralino CDM models, it may be possible
to detect both a WIMP and an axion as dark matter relics. We also discuss
possible modifications of our results due to production and decay of saxions.
In the appendices, we present expressions for the Hubble expansion rate and the
axion and neutralino relic densities in radiation, matter and decaying-particle
dominated universes.Comment: 31 pages including 21 figure
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