3,443 research outputs found
Dependency structure matrix, genetic algorithms, and effective recombination
In many different fields, researchers are often confronted by problems arising from complex systems. Simple heuristics or even enumeration works quite well on small and easy problems; however, to efficiently solve large and difficult problems, proper decomposition is the key. In this paper, investigating and analyzing interactions between components of complex systems shed some light on problem decomposition. By recognizing three bare-bones interactions-modularity, hierarchy, and overlap, facet-wise models arc developed to dissect and inspect problem decomposition in the context of genetic algorithms. The proposed genetic algorithm design utilizes a matrix representation of an interaction graph to analyze and explicitly decompose the problem. The results from this paper should benefit research both technically and scientifically. Technically, this paper develops an automated dependency structure matrix clustering technique and utilizes it to design a model-building genetic algorithm that learns and delivers the problem structure. Scientifically, the explicit interaction model describes the problem structure very well and helps researchers gain important insights through the explicitness of the procedure.This work was sponsored by Taiwan National Science Council under grant NSC97-
2218-E-002-020-MY3, U.S. Air Force Office of Scientific Research, Air Force Material
Command, USAF, under grants FA9550-06-1-0370 and FA9550-06-1-0096, U.S. National
Science Foundation under CAREER grant ECS-0547013, ITR grant DMR-03-25939 at
Materials Computation Center, grant ISS-02-09199 at US National Center for Supercomputing Applications, UIUC, and the Portuguese Foundation for Science and Technology
under grants SFRH/BD/16980/2004 and PTDC/EIA/67776/2006
Nuclear membrane disassembly and rupture
The nuclear envelope consists of two membranes traversed by nuclear pore complexes. The outer membrane is continuous with the endoplasmic reticulum. At mitosis nuclear pore complexes are dismantled and membranes disperse. The mechanism of dispersal is controversial: one view is that membranes feed into the endoplasmic reticulum, another is that they vesiculate. Using Xenopus egg extracts, nuclei have been assembled and then induced to breakdown by addition of metaphase extract. Field emission scanning electron microscopy was used to study disassembly. Strikingly, endoplasmic reticulum-like membrane tubules form from the nuclear surface after the addition of metaphase extracts, but vesicles were also observed. Microtubule inhibitors slowed but did not prevent membrane removal, whereas Brefeldin A, which inhibits vesicle formation, stops membrane disassembly, suggesting that vesiculation is necessary. Structures that looked like coated buds were observed and buds were labelled for β-COP. We show that nuclear pore complexes are dismantled and the pore closed prior to membrane rupturing, suggesting that rupturing is an active process rather than a result of enlargement of nuclear pores
Application Of The Domestic Production Activities Tax Deduction (Relating To A Wide Range Of Industries)
Internal Revenue Code Section 199 is the domestic production activities deduction, which was enacted under the American Jobs Creation Act of 2004. This new deduction was to help compensate the repeal of the exterritorial income exclusion. Section 199 was intended to lower the tax burden on domestic manufacturers as well as to attract new investments in domestic manufacturing facilities. The deduction would yield tax breaks for certain types of businesses ranging large to small that predominately manufacture, produce, grow, or extract tangible personal property entirely or partially within the United States. The types of businesses, specifically, that will have an impact from Section 199 would be those in the film and sound recordings industries, companies in the construction business, and those in the field of architectural and engineering. In addition, those that qualified as doing business in any of the specific industries falling under Section 199 must be located and providing services in the United States. The Section 199 tax break will also benefit those in the business of producing electricity, natural gas, and water in the United States. The deduction is allowed to be taken for taxable years beginning after 2004, which creates many challenges. First, Section 199 establishes detailed tax concepts conditions, de minimis rules, exceptions, and safe harbors. Second, the deduction forces many businesses to implement new accounting systems to classify between qualifying and non-qualifying activities. All in all, this report explains how Section 199 works as well as benefits specific industries. However, important production eligibility issues remain in determining the production deduction for tangible property, which are the central items focused throughout this article. Furthermore, the research contain within, covers the guidance in Notice 2005-14, along with the proposed and final regulations to the rules under Section 199. An understanding of these rules will provide additional opportunities to qualify property and take advantage of tax breaks, yielding a better financial result to the taxpayer
Dark matter in gravity-mediated supersymmetry breaking
In R parity conserving supersymmetric theories the lightest superpartner
(LSP) is stable. The LSPs may comprise a large fraction of the energy density
of the current universe, which would lead to dramatic astrophysical
consequences. In this talk, I discuss some of the main lessons we have learned
about supersymmetric models from relic abundance considerations of the LSP.Comment: 6 pages, LaTeX with espcrc2.sty, to be published in the "Proceedings
of the 5th International Conference on Supersymmetries in Physics (SUSY 97)",
Philadelphia, Pennsylvania, May 27-31, 199
Differences in long-term physical activity trajectories among individuals with chronic widespread pain : A secondary analysis of a randomized controlled trial
Funding Sources: The MUSICIAN trial was funded by Arthritis Research UK, Chesterfield, UK (Grant award number 17292) and the MELODIC study was funded by NHS Grampian Endowment Grant, Project No: 14/40.Peer reviewedPostprin
A Complete Spectroscopic Survey of the Milky Way satellite Segue 1: Dark matter content, stellar membership and binary properties from a Bayesian analysis
We introduce a comprehensive analysis of multi-epoch stellar line-of-sight
velocities to determine the intrinsic velocity dispersion of the ultrafaint
satellites of the Milky Way. Our method includes a simultaneous Bayesian
analysis of both membership probabilities and the contribution of binary
orbital motion to the observed velocity dispersion within a 14-parameter
likelihood. We apply our method to the Segue 1 dwarf galaxy and conclude that
Segue 1 is a dark-matter-dominated galaxy at high probability with an intrinsic
velocity dispersion of 3.7^{+1.4}_{-1.1} km/sec. The dark matter halo required
to produce this dispersion must have an average density of 2.5^{+4.1}_{-1.9}
solar mass/pc^3 within a sphere that encloses half the galaxy's stellar
luminosity. This is the highest measured density of dark matter in the Local
Group. Our results show that a significant fraction of the stars in Segue 1 may
be binaries with the most probable mean period close to 10 years, but also
consistent with the 180 year mean period seen in the solar vicinity at about 1
sigma. Despite this binary population, the possibility that Segue 1 is a bound
star cluster with the observed velocity dispersion arising from the orbital
motion of binary stars is disfavored by the multi-epoch stellar velocity data
at greater than 99% C.L. Finally, our treatment yields a projected
(two-dimensional) half-light radius for the stellar profile of Segue 1 of
28^{+5}_{-4} pc, in excellent agreement with photometric measurements.Comment: 15 pages, 19 figure
The development of the Pictish symbol system: inscribing identity beyond the edges of Empire
The date of unique symbolic carvings, from various contexts across north and east Scotland, has been debated for over a century. Excavations at key sites and direct dating of engraved bone artefacts have allowed for a more precise chronology, extending from the third/fourth centuries AD, broadly contemporaneous with other non-vernacular scripts developed beyond the frontiers of the Roman Empire, to the ninth century AD. These symbols were probably an elaborate, non-alphabetic writing system, a Pictish response to broader European changes in power and identity during the transition from the Roman Empire to the early medieval period
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