26,945 research outputs found
Extracting an arbitrary relative phase from a multiqubit two-component entangled state
We show that an arbitrary relative phase can be extracted from a multiqubit
two-component (MTC) entangled state by local Hadamard transformations and
measurements along a single basis only. In addition, how to distinguish a MTC
entangled state with an arbitrary entanglement degree and relative phase from a
class of multiqubit mixed states is discussed.Comment: 4 pages, REVTEX, accepted by Physical Review
Combining All Pairs Shortest Paths and All Pairs Bottleneck Paths Problems
We introduce a new problem that combines the well known All Pairs Shortest
Paths (APSP) problem and the All Pairs Bottleneck Paths (APBP) problem to
compute the shortest paths for all pairs of vertices for all possible flow
amounts. We call this new problem the All Pairs Shortest Paths for All Flows
(APSP-AF) problem. We firstly solve the APSP-AF problem on directed graphs with
unit edge costs and real edge capacities in
time,
where is the number of vertices, is the number of distinct edge
capacities (flow amounts) and is the time taken
to multiply two -by- matrices over a ring. Secondly we extend the problem
to graphs with positive integer edge costs and present an algorithm with
worst case time complexity, where is
the upper bound on edge costs
Rampant exchange of the structure and function of extramembrane domains between membrane and water soluble proteins.
Of the membrane proteins of known structure, we found that a remarkable 67% of the water soluble domains are structurally similar to water soluble proteins of known structure. Moreover, 41% of known water soluble protein structures share a domain with an already known membrane protein structure. We also found that functional residues are frequently conserved between extramembrane domains of membrane and soluble proteins that share structural similarity. These results suggest membrane and soluble proteins readily exchange domains and their attendant functionalities. The exchanges between membrane and soluble proteins are particularly frequent in eukaryotes, indicating that this is an important mechanism for increasing functional complexity. The high level of structural overlap between the two classes of proteins provides an opportunity to employ the extensive information on soluble proteins to illuminate membrane protein structure and function, for which much less is known. To this end, we employed structure guided sequence alignment to elucidate the functions of membrane proteins in the human genome. Our results bridge the gap of fold space between membrane and water soluble proteins and provide a resource for the prediction of membrane protein function. A database of predicted structural and functional relationships for proteins in the human genome is provided at sbi.postech.ac.kr/emdmp
Network rewiring is an important mechanism of gene essentiality change.
Gene essentiality changes are crucial for organismal evolution. However, it is unclear how essentiality of orthologs varies across species. We investigated the underlying mechanism of gene essentiality changes between yeast and mouse based on the framework of network evolution and comparative genomic analysis. We found that yeast nonessential genes become essential in mouse when their network connections rapidly increase through engagement in protein complexes. The increased interactions allowed the previously nonessential genes to become members of vital pathways. By accounting for changes in gene essentiality, we firmly reestablished the centrality-lethality rule, which proposed the relationship of essential genes and network hubs. Furthermore, we discovered that the number of connections associated with essential and non-essential genes depends on whether they were essential in ancestral species. Our study describes for the first time how network evolution occurs to change gene essentiality
Pay-to-Delay Settlements: The Circuit-Splitting Headache Plaguing Big Pharma
At its passage, the Hatch-Waxman Act was hailed as a much-needed step in making generic drugs more readily available to consumers, easing some of the heavy burdens placed on consumers by the necessary, but flawed, patent system that essentially granted brand-name pharmaceutical manufacturers a de facto economic monopoly over their drugs. One consequence of the Act, unforeseen by legislators and regulators, was the creation of a perverse incentive on behalf of pharmaceutical patent holders to pay alleged patent infringers substantial cash payments to delay entry into the particular drug market. These pay-to-delay settlements--or reverse-payment settlements--have been at the center of a prolific debate among economists, legal theorists, regulators, and various industry experts on the appropriate relationship between antitrust law and patent law. This troubling byproduct of the Hatch-Waxman Act has also slowly created a definitive split among the federal circuit courts over the past ten years. The conflict is now coming to a head as the Supreme Court reviews the legality of reverse-payment settlements in FTC v. Watson Pharmaceuticals. This Note recommends that the Court recognize that, by removing the patent validity testing from the courtroom to the settlement negotiation table, the patentee-plaintiffs also removed themselves from the protection against antitrust scrutiny that a patent provides. As such, certain evidence of reverse payments should give rise to a rebuttable presumption of an illegal restraint of trade, given its clear anticompetitive implications
Online Maximum k-Coverage
We study an online model for the maximum k-vertex-coverage problem, where given a graph G = (V,E) and an integer k, we ask for a subset A ⊆ V, such that |A | = k and the number of edges covered by A is maximized. In our model, at each step i, a new vertex vi is revealed, and we have to decide whether we will keep it or discard it. At any time of the process, only k vertices can be kept in memory; if at some point the current solution already contains k vertices, any inclusion of any new vertex in the solution must entail the irremediable deletion of one vertex of the current solution (a vertex not kept when revealed is irremediably deleted). We propose algorithms for several natural classes of graphs (mainly regular and bipartite), improving on an easy 1/2-competitive ratio. We next settle a set-version of the problem, called maximum k-(set)-coverage problem. For this problem we present an algorithm that improves upon former results for the same model for small and moderate values of k
CDF Multi-Muon Events and Singlet Extensions of the MSSM
We discuss a generalization of the minimal supersymmetric extension of the
Standard Model in the form of three additional singlet superfields, which would
explain the essential features of the CDF multi-muon events presented recently:
a large production cross section of ~ 100 pb originates from the production of
a CP-odd scalar A with a mass in the 70 - 80 GeV range and a large value of
tan(beta) ~ 40. The CP-odd scalar A decays dominantly into CP-odd and CP-even
scalars a_1 and h_1, which generate decay cascades h_1 -> 2 h_2 -> 4 a_2 -> 8
tau-leptons, and a_1 -> h_1 a_2 with h_1 decaying as above. The decay a_2 ->
tau+ tau- is slow, leading to a lifetime of O(20) ps. The phenomenology of the
model differs from similar scenarios presented before in that one of the two
cascades leads to 10 instead of 8 tau-leptons, and additional production
processes like associate A production with b b-bar pairs are relevant.Comment: 10 pages, comments on the required total cross section added, to
appear in MPL
Subdwarf B Stars from the ESO Supernova Ia Progenitor Survey -- Observation versus Theory
Original paper can be found at: http://www.astrosociety.org/pubs/cs/328.html--Copyright Astronomical Society of the PacificWe present the analysis of a high-quality sample of optical spectra for 76 sdB stars from the ESO Supernova Ia Progenitor Survey. Effective temperature, surface gravity, and photospheric helium abundance were derived from line profile fits. We demonstrate that our subsample of 52 single-lined sdB stars is a useful tool to compare observation and theory. The predictions of population synthesis models for close binary evolution are compared to our data. We show that the simulations cover the observed parameter range of sdBs, but fail to reproduce the observed distribution in detail
A Study On The Performance Of Limestone Roughing Filter For The Removal Of Turbidity, Suspended Solids, Biochemical Oxygen Demand And Coliform Organisms Using Wastewater From The Inlet Of Domestic Wastewater Oxidation Pond [TD444. T377 2006 f rb].
Penurasan kasar pada hakikatnya adalah bertujuan untuk melindungi penapis pasir perlahan dengan cara mengurangkan kekeruhan influen dan pepejal terampai pada tahap yang mana ianya boleh beroperasi dengan berkesan.
The original purpose of roughing filtration is to protect slow sand filters by reducing influent turbidity and suspended solids to a level that is effective for operation.
Roughing filtration presents a promising method for improving raw water quality without using any chemicals
The Higgs Sector in a Extension of the MSSM
We consider the Higgs sector in an extension of the MSSM with extra SM
singlets, involving an extra gauge symmetry, in which the
domain-wall problem is avoided and the effective parameter is decoupled
from the new gauge boson mass. The model involves a rich Higgs
structure very different from that of the MSSM. In particular, there are large
mixings between Higgs doublets and the SM singlets, significantly affecting the
Higgs spectrum, production cross sections, decay modes, existing exclusion
limits, and allowed parameter range. Scalars considerably lighter than the LEP2
bound (114 GeV) are allowed, and the range is both allowed
and theoretically favored. Phenomenologically, we concentrate our study on the
lighter (least model-dependent, yet characteristic) Higgs particles with
significant SU(2)-doublet components to their wave functions, for the case of
no explicit CP violation in the Higgs sector. We consider their spectra,
including the dominant radiative corrections to their masses from the top/stop
loop. We computed their production cross sections and reexamine the existing
exclusion limits at LEP2. We outline the searching strategy for some
representative scenarios at a future linear collider. We emphasize that
gaugino, Higgsino, and singlino decay modes are indicative of extended models
and have been given little attention. We present a comprehensive list of model
scenarios in the Appendices.Comment: 49 pages, 17 figure
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