8,341 research outputs found
Role of infrainguinal bypass in Buerger's disease: An eighteen-year experience
Objectives:The role of bypass to the distal arteries for patients with Buerger's disease (thromboangiitis or TAO) remains controversial because of the high incidence of graft failure. We retrospectively reviewed the results of 71 bypasses to evaluate their efficacy.Materials and methods:We performed 71 autogenous vein bypasses in 61 patients with TAO. Of the patients, 97% were heavy smokers. The indications for surgery were claudication in 41%, and ischaemic ulcer or gangrene in 59%. Of the bypasses 85% were to the crural arteries or to the arteries below the ankle. The grafts used were 53 single saphenous veins, and 18 venovenous composite grafts.Results:There were 38 graft failures, the main causes including anastomosis to a diseased artery, disease progression (which occurred in smokers after surgery), and vein graft stenosis. Of 38, 10 were restored to patency by revision surgery. Primary and secondary patency rates were 48.8% and 62.5% at 5 years, and 43.0% and 56.3% at 10 years, respectively. The patency rates of the postoperative non-smoking group was significantly higher than that of the smoking group (66.8% vs. 34.7%, p < 0.05). Thirty-six patients (59%) had successful revascularisation and returned to full-time work. However, of 28 with secondary failure, 11 underwent amputation, while 14 had persistent disabling claudication.Conclusion:Bypass to the distal arteries is an effective treatment for TAO patients, and the long-term patency is quite satisfactory as long as patients stop smoking
Load distribution in weighted complex networks
We study the load distribution in weighted networks by measuring the
effective number of optimal paths passing through a given vertex. The optimal
path, along which the total cost is minimum, crucially depend on the cost
distribution function . In the strong disorder limit, where , the load distribution follows a power law both in the
Erd\H{o}s-R\'enyi (ER) random graphs and in the scale-free (SF) networks, and
its characteristics are determined by the structure of the minimum spanning
tree. The distribution of loads at vertices with a given vertex degree also
follows the SF nature similar to the whole load distribution, implying that the
global transport property is not correlated to the local structural
information. Finally, we measure the effect of disorder by the correlation
coefficient between vertex degree and load, finding that it is larger for ER
networks than for SF networks.Comment: 4 pages, 4 figures, final version published in PR
Probing Spin-Charge Relation by Magnetoconductance in One-Dimensional Polymer Nanofibers
Polymer nanofibers are one-dimensional organic hydrocarbon systems containing
conducting polymers where the non-linear local excitations such as solitons,
polarons and bipolarons formed by the electron-phonon interaction were
predicted. Magnetoconductance (MC) can simultaneously probe both the spin and
charge of these mobile species and identify the effects of electron-electron
interactions on these nonlinear excitations. Here we report our observations of
a qualitatively different MC in polyacetylene (PA) and in polyaniline (PANI)
and polythiophene (PT) nanofibers. In PA the MC is essentially zero, but it is
present in PANI and PT. The universal scaling behavior and the zero (finite) MC
in PA (PANI and PT) nanofibers provide evidence of Coulomb interactions between
spinless charged solitons (interacting polarons which carry both spin and
charge)
Neutrino Mass and Grand Unification
Seesaw mechanism appears to be the simplest and most appealing way to
understand small neutrino masses observed in recent experiments. It introduces
three right handed neutrinos with heavy masses to the standard model, with at
least one mass required by data to be close to the scale of conventional grand
unified theories. This may be a hint that the new physics scale implied by
neutrino masses and grand unification of forces are one and the same. Taking
this point of view seriously, I explore different ways to resolve the puzzle of
large neutrino mixings in grand unified theories such as SO(10) and models
based on its subgroup .Comment: 17 pages, 5 figures; Invited talk at the Nobel Symposium 129 on
Neutrinos at Haga Slott, Sweden, August, 200
General Formulation for Proton Decay Rate in Minimal Supersymmetric SO(10) GUT
We make an explicit formulation for the proton decay rate in the minimal
renormalizable supersymmetric (SUSY) SO(10) model. In this model, the Higgs
fields consist of and SO(10) representations in
the Yukawa interactions with matter and of , , , and representations in the Higgs potential. We present all
the mass matrices for the Higgs fields contained in this minimal SUSY SO(10)
model. Finally, we discuss the threshold effects of these Higgs fields on the
gauge coupling unification.Comment: 32 pages, typos are corrected, a few references and comments to the
papers arXiv:hep-ph/0204097 and arXiv:hep-ph/0402122 are adde
Synthetic RNA Silencing of Actinorhodin Biosynthesis in Streptomyces coelicolor A3(2)
We demonstrate the first application of synthetic RNA gene silencers in Streptomyces coelicolor A3(2). Peptide nucleic acid and expressed antisense RNA silencers successfully inhibited actinorhodin production. Synthetic RNA silencing was target-specific and is a new tool for gene regulation and metabolic engineering studies in Streptomyces.Peer reviewe
Anchoring Bias in Online Voting
Voting online with explicit ratings could largely reflect people's
preferences and objects' qualities, but ratings are always irrational, because
they may be affected by many unpredictable factors like mood, weather, as well
as other people's votes. By analyzing two real systems, this paper reveals a
systematic bias embedding in the individual decision-making processes, namely
people tend to give a low rating after a low rating, as well as a high rating
following a high rating. This so-called \emph{anchoring bias} is validated via
extensive comparisons with null models, and numerically speaking, the extent of
bias decays with interval voting number in a logarithmic form. Our findings
could be applied in the design of recommender systems and considered as
important complementary materials to previous knowledge about anchoring effects
on financial trades, performance judgements, auctions, and so on.Comment: 5 pages, 4 tables, 5 figure
Folded Supersymmetry and the LEP Paradox
We present a new class of models that stabilize the weak scale against
radiative corrections up to scales of order 5 TeV without large corrections to
precision electroweak observables. In these `folded supersymmetric' theories
the one loop quadratic divergences of the Standard Model Higgs field are
cancelled by opposite spin partners, but the gauge quantum numbers of these new
particles are in general different from those of the conventional
superpartners. This class of models is built around the correspondence that
exists in the large N limit between the correlation functions of supersymmetric
theories and those of their non-supersymmetric orbifold daughters. By
identifying the mechanism which underlies the cancellation of one loop
quadratic divergences in these theories, we are able to construct simple
extensions of the Standard Model which are radiatively stable at one loop.
Ultraviolet completions of these theories can be obtained by imposing suitable
boundary conditions on an appropriate supersymmetric higher dimensional theory
compactified down to four dimensions. We construct a specific model based on
these ideas which stabilizes the weak scale up to about 20 TeV and where the
states which cancel the top loop are scalars not charged under Standard Model
color. Its collider signatures are distinct from conventional supersymmetric
theories and include characteristic events with hard leptons and missing
energy.Comment: 18 pages, 5 figures, references correcte
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