Partitioning Complex Networks via Size-constrained Clustering

The most commonly used method to tackle the graph partitioning problem in practice is the multilevel approach. During a coarsening phase, a multilevel graph partitioning algorithm reduces the graph size by iteratively contracting nodes and edges until the graph is small enough to be partitioned by some other algorithm. A partition of the input graph is then constructed by successively transferring the solution to the next finer graph and applying a local search algorithm to improve the current solution. In this paper, we describe a novel approach to partition graphs effectively especially if the networks have a highly irregular structure. More precisely, our algorithm provides graph coarsening by iteratively contracting size-constrained clusterings that are computed using a label propagation algorithm. The same algorithm that provides the size-constrained clusterings can also be used during uncoarsening as a fast and simple local search algorithm. Depending on the algorithm's configuration, we are able to compute partitions of very high quality outperforming all competitors, or partitions that are comparable to the best competitor in terms of quality, hMetis, while being nearly an order of magnitude faster on average. The fastest configuration partitions the largest graph available to us with 3.3 billion edges using a single machine in about ten minutes while cutting less than half of the edges than the fastest competitor, kMetis

On the statistical significance of the conductance quantization

Recent experiments on atomic-scale metallic contacts have shown that the quantization of the conductance appears clearly only after the average of the experimental results. Motivated by these results we have analyzed a simplified model system in which a narrow neck is randomly coupled to wide ideal leads, both in absence and presence of time reversal invariance. Based on Random Matrix Theory we study analytically the probability distribution for the conductance of such system. As the width of the leads increases the distribution for the conductance becomes sharply peaked close to an integer multiple of the quantum of conductance. Our results suggest a possible statistical origin of conductance quantization in atomic-scale metallic contacts.Comment: 4 pages, Tex and 3 figures. To be published in PR

A Current Induced Transition in atomic-sized contacts of metallic Alloys

We have measured conductance histograms of atomic point contacts made from the noble-transition metal alloys CuNi, AgPd, and AuPt for a concentration ratio of 1:1. For all alloys these histograms at low bias voltage (below 300 mV) resemble those of the noble metals whereas at high bias (above 300 mV) they resemble those of the transition metals. We interpret this effect as a change in the composition of the point contact with bias voltage. We discuss possible explanations in terms of electromigration and differential diffusion induced by current heating.Comment: 5 pages, 6 figure

In Vitro Wound Healing Improvement By Low-level Laser Therapy Application In Cultured Gingival Fibroblasts

The aim of this study was to determine adequate energy doses using specific parameters of LLLT to produce biostimulatory effects on human gingival fibroblast culture. Cells (3 10 4 cells/cm 2) were seeded on 24-well acrylic plates using plain DMEM supplemented with 10 fetal bovine serum. After 48-hour incubation with 5 CO2 at 37C, cells were irradiated with a InGaAsP diode laser prototype (LASERTable; 780 3 nm; 40mW) with energy doses of 0.5, 1.5, 3, 5, and 7J/cm 2. Cells were irradiated every 24h totalizing 3 applications. Twenty-four hours after the last irradiation, cell metabolism was evaluated by the MTT assay and the two most effective doses (0.5 and 3J/cm 2) were selected to evaluate the cell number (trypan blue assay) and the cell migration capacity (wound healing assay; transwell migration assay). Data were analyzed by the Kruskal-Wallis and Mann-Whitney nonparametric tests with statistical significance of 5. Irradiation of the fibroblasts with 0.5 and 3J/cm 2 resulted in significant increase in cell metabolism compared with the nonrradiated group (P 0.05). Both energy doses promoted significant increase in the cell number as well as in cell migration (P 0.05). These results demonstrate that, under the tested conditions, LLLT promoted biostimulation of fibroblasts in vitro. Copyright © 2012 Fernanda G. Basso et al.Hkkinen, L., Uitto, V.J., Larjava, H., Cell biology of gingival wound healing (2000) Periodontology 2000, 24 (1), pp. 127-152Kreisler, M., Christoffers, A.B., Al-Haj, H., Willershausen, B., D'Hoedt, B., Low level 809-nm diode laser-induced in vitro stimulation of the proliferation of human gingival fibroblasts (2002) Lasers in Surgery and Medicine, 30 (5), pp. 365-369. , DOI 10.1002/lsm.10060Posten, W., Wrone, D.A., Dover, J.S., Arndt, K.A., Silapunt, S., Alam, M., Low-level laser therapy for wound healing: Mechanism and efficacy (2005) Dermatologic Surgery, 31 (3), pp. 334-340Saygun, I., Karacay, S., Serdar, M., Ural, A.U., Sencimen, M., Kurtis, B., Effects of laser irradiation on the release of basic fibroblast growth factor (bFGF), insulin like growth factor-1 (IGF-1), and receptor of IGF-1 (IGFBP3) from gingival fibroblasts (2008) Lasers in Medical Science, 23 (2), pp. 211-215. , DOI 10.1007/s10103-007-0477-3Skopin, M.D., Molitor, S.C., Effects of near-infrared laser exposure in a cellular model of wound healing (2009) Photodermatology Photoimmunology and Photomedicine, 25 (2), pp. 75-80Hakki, S.S., Bozkurt, S.B., Effects of different setting of diode laser on the mRNA expression of growth factors and type i collagen of human gingival fibroblasts (2012) Lasers in Medical Science, 27 (2), pp. 325-331Peplow, P.V., Chung, T.Y., Baxter, G.D., Laser photobiomodulation of proliferation of cells in culture: A review of human and animal studies (2010) Photomedicine and Laser Surgery, 28, pp. 3-S40. , supplement 1Basso, F.G., Oliveira, C.F., Kurachi, C., Hebling, J., Costa, C.A., Biostimulatory effect of low-level laser therapy on keratinocytes in vitro Lasers in Medical Science, , In pressOliveira, C.F., Basso, F.G., Lins, E.C., Kurachi, C., Hebling, J., Bagnato, V.S., De Souza Costa, C.A., In vitro effect of low-level laser on odontoblast-like cells (2011) Laser Physics Letters, 8 (2), pp. 155-163Mosmann, T., Rapid colorimetric assay for cellular growth and survival: Application to proliferation and cytotoxicity assays (1983) Journal of Immunological Methods, 65 (1-2), pp. 55-63Wiegand, C., Hipler, U., Methods for the measurement of cell and tissue compatibility including tissue regeneration process (2008) GMS Krankenhaushygiene Interdisziplinr, 3 (1), pp. 1863-5245Hoang, A.M., Oates, T.W., Cochran, D.L., In vitro wound healing responses to enamel matrix derivative (2000) Journal of Periodontology, 71 (8), pp. 1270-1277Liang, C.-C., Park, A.Y., Guan, J.-L., In vitro scratch assay: A convenient and inexpensive method for analysis of cell migration in vitro (2007) Nature Protocols, 2 (2), pp. 329-333. , DOI 10.1038/nprot.2007.30, PII NPROT.2006.30Cceres, M., Romero, A., Copaja, M., Daz-Araya, G., Martnez, J., Smith, P.C., Simvastatin alters fibroblastic cell responses involved in tissue repair (2011) Journal of Periodontal Research, 46 (4), pp. 456-463Chor, A., De Azevedo, A.M., Maiolino, A., Nucci, M., Successful treatment of oral lesions of chronic lichenoid graft-vs.-host disease by the addition of low-level laser therapy to systemic immunosuppression (2004) European Journal of Haematology, 72 (3), pp. 222-224. , DOI 10.1046/j.0902-4441.2003.00202.xAbramoff, M.M.F., Lopes, N.N.F., Lopes, L.A., Dib, L.L., Guilherme, A., Caran, E.M., Barreto, A.D., Petrilli, A.S., Low-level laser therapy in the prevention and treatment of chemotherapy-induced oral mucositis in young patients (2008) Photomedicine and Laser Surgery, 26 (4), pp. 393-400Woodruff, L.D., Bounkeo, J.M., Brannon, W.M., Dawes Jr., K.S., Barham, C.D., Waddell, D.L., Enwemeka, C.S., The efficacy of laser therapy in wound repair: A meta-analysis of the literature (2004) Photomedicine and Laser Surgery, 22 (3), pp. 241-247. , DOI 10.1089/1549541041438623Damante, C.A., De Micheli, G., Miyagi, S.P.H., Feist, I.S., Marques, M.M., Effect of laser phototherapy on the release of fibroblast growth factors by human gingival fibroblasts (2009) Lasers in Medical Science, 24 (6), pp. 885-891Almeida-Lopes, L., Rigau, J., Zangaro, R.A., Guidugli-Neto, J., Jaeger, M.M.M., Comparison of the low level laser therapy effects on cultured human gingival fibroblasts proliferation using different irradiance and same fluence (2001) Lasers in Surgery and Medicine, 29 (2), pp. 179-184. , DOI 10.1002/lsm.1107Alghamdi, K.M., Kumar, A., Moussa, N.A., Low-level laser therapy: A useful technique for enhancing the proliferation of various cultured cells (2011) Lasers in Medical Science, 27 (1), pp. 237-249Gao, X., Xing, D., Molecular mechanisms of cell proliferation induced by low power laser irradiation (2009) Journal of Biomedical Science, 164Karu, T.I., Pyatibrat, L.V., Kolyakov, S.F., Afanasyeva, N.I., Absorption measurements of a cell monolayer relevant to phototherapy: Reduction of cytochrome c oxidase under near IR radiation (2005) Journal of Photochemistry and Photobiology B: Biology, 81 (2), pp. 98-106. , DOI 10.1016/j.jphotobiol.2005.07.002, PII S1011134405001302Eells, J.T., Henry, M.M., Summerfelt, P., Wong-Riley, M.T.T., Buchmann, E.V., Kane, M., Whelan, N.T., Whelan, H.T., Therapeutic photobiomodulation for methanol-induced retinal toxicity (2003) Proceedings of the National Academy of Sciences of the United States of America, 100 (6), pp. 3439-3444. , DOI 10.1073/pnas.0534746100Zhang, L., Xing, D., Gao, X., Wu, S., Low-power laser irradiation promotes cell proliferation by activating PI3K/Akt pathway (2009) Journal of Cellular Physiology, 219 (3), pp. 553-562Azevedo, L.H., De Paula Eduardo, F., Moreira, M.S., De Paula Eduardo, C., Marques, M.M., Influence of different power densities of LILT on cultured human fibroblast growth: A pilot study (2006) Lasers in Medical Science, 21 (2), pp. 86-89. , DOI 10.1007/s10103-006-0379-9Lagan, K.M., Alyson Clements, B., McDonough, S., David Baxter, G., Low intensity laser therapy (830nm) in the management of minor postsurgical wounds: A controlled clinical study (2001) Lasers in Surgery and Medicine, 28 (1), pp. 27-32. , DOI 10.1002/1096-9101(2 001)28:13.0.CO;2-

Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares

The extreme ultraviolet portion of the solar spectrum contains a wealth of diagnostic tools for probing the lower solar atmosphere in response to an injection of energy, particularly during the impulsive phase of solar flares. These include temperature and density sensitive line ratios, Doppler shifted emission lines and nonthermal broadening, abundance measurements, differential emission measure profiles, and continuum temperatures and energetics, among others. In this paper I shall review some of the advances made in recent years using these techniques, focusing primarily on studies that have utilized data from Hinode/EIS and SDO/EVE, while also providing some historical background and a summary of future spectroscopic instrumentation.Comment: 34 pages, 8 figures. Submitted to Solar Physics as part of the Topical Issue on Solar and Stellar Flare

Energetics, forces, and quantized conductance in jellium modeled metallic nanowires

Energetics and quantized conductance in jellium modeled nanowires are investigated using the local density functional based shell correction method, extending our previous study of uniform in shape wires [C. Yannouleas and U. Landman, J. Phys. Chem. B 101, 5780 (1997)] to wires containing a variable shaped constricted region. The energetics of the wire (sodium) as a function of the length of the volume conserving, adiabatically shaped constriction leads to formation of self selecting magic wire configurations. The variations in the energy result in oscillations in the force required to elongate the wire and are directly correlated with the stepwise variations of the conductance of the nanowire in units of 2e^2/h. The oscillatory patterns in the energetics and forces, and the correlated stepwise variation in the conductance are shown, numerically and through a semiclassical analysis, to be dominated by the quantized spectrum of the transverse states at the narrowmost part of the constriction in the wire.Comment: Latex/Revtex, 11 pages with 5 Postscript figure

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio