Greedy Selfish Network Creation

We introduce and analyze greedy equilibria (GE) for the well-known model of selfish network creation by Fabrikant et al.[PODC'03]. GE are interesting for two reasons: (1) they model outcomes found by agents which prefer smooth adaptations over radical strategy-changes, (2) GE are outcomes found by agents which do not have enough computational resources to play optimally. In the model of Fabrikant et al. agents correspond to Internet Service Providers which buy network links to improve their quality of network usage. It is known that computing a best response in this model is NP-hard. Hence, poly-time agents are likely not to play optimally. But how good are networks created by such agents? We answer this question for very simple agents. Quite surprisingly, naive greedy play suffices to create remarkably stable networks. Specifically, we show that in the SUM version, where agents attempt to minimize their average distance to all other agents, GE capture Nash equilibria (NE) on trees and that any GE is in 3-approximate NE on general networks. For the latter we also provide a lower bound of 3/2 on the approximation ratio. For the MAX version, where agents attempt to minimize their maximum distance, we show that any GE-star is in 2-approximate NE and any GE-tree having larger diameter is in 6/5-approximate NE. Both bounds are tight. We contrast these positive results by providing a linear lower bound on the approximation ratio for the MAX version on general networks in GE. This result implies a locality gap of $\Omega(n)$ for the metric min-max facility location problem, where n is the number of clients.Comment: 28 pages, 8 figures. An extended abstract of this work was accepted at WINE'1

Computing Accurate Probabilistic Estimates of One-D Entropy from Equiprobable Random Samples

We develop a simple Quantile Spacing (QS) method for accurate probabilistic estimation of one-dimensional entropy from equiprobable random samples, and compare it with the popular Bin-Counting (BC) method. In contrast to BC, which uses equal-width bins with varying probability mass, the QS method uses estimates of the quantiles that divide the support of the data generating probability density function (pdf) into equal-probability-mass intervals. Whereas BC requires optimal tuning of a bin-width hyper-parameter whose value varies with sample size and shape of the pdf, QS requires specification of the number of quantiles to be used. Results indicate, for the class of distributions tested, that the optimal number of quantile-spacings is a fixed fraction of the sample size (empirically determined to be ~0.25-0.35), and that this value is relatively insensitive to distributional form or sample size, providing a clear advantage over BC since hyperparameter tuning is not required. Bootstrapping is used to approximate the sampling variability distribution of the resulting entropy estimate, and is shown to accurately reflect the true uncertainty. For the four distributional forms studied (Gaussian, Log-Normal, Exponential and Bimodal Gaussian Mixture), expected estimation bias is less than 1% and uncertainty is relatively low even for very small sample sizes. We speculate that estimating quantile locations, rather than bin-probabilities, results in more efficient use of the information in the data to approximate the underlying shape of an unknown data generating pdf.Comment: 23 pages, 12 figure

Corrosion polarization behavior and microstructuralanalysis of AA1070 aluminium silicon carbide matrix composites in acid chloride concentrations

The effect of SiC content and NaCl concentration on the corrosion resistance of AA1070 aluminium in 2 M H2SO4 was evaluated with potentiodynamic polarization technique, open circuit potential measurement (OCP) and optical microscopy. Results showed SiC increased the corrosion susceptibility of the alloy at lower NaCl concentrations compared to results obtained at 0% NaCl which showed significant decrease in corrosion rates, with maximum inhibition efficiency of 90.84% at 20% SiC content. The corrosion rates decreased at higher NaCl concentration,with maximum inhibition efficiency of 94.12 and 77.27% at 20% SiC. Alloy samples in 2 M H2SO4/0% NaCl at 0 and 20% SiC visibly decreased in OCP value over wide variation compared to samples with varying NaCl concentration due to loss of passivity. OCP values for alloys at varying NaCl concentration decreased over a very short variation due to repassivation. Statistical data showed silicon carbide to be the only relevant variable responsible for the corrosion rate values with F-values of 8.85 corresponding to a percentage significance of 54.8%. Optical images showed the presence of corrosion pits of smaller dimension, yet deeper on the morphology of the alloy without silicon carbide compared the alloy containing it, whose corrosion pits, seems wider but very shallo

EpiFactors : a comprehensive database of human epigenetic factors and complexes

Altres ajuts: Russian Fund For Basic Research(RFFI)grant 14-04-0018 i grant 15-34-20423, Ake Olsson's foundation, Swedish Cancer foundation, Swedish Childhood cancer foundation, Dynasty Foundation Fellowship, RIKEN Omics Science Center, RIKEN Preventive Medicine and Diagnosis Innovation Program i RIKEN Center for Life Science Technologies.Abstract: Epigenetics refers to stable and long-term alterations of cellular traits that are not caused by changes in the DNA sequence per se. Rather, covalent modifications of DNA and histones affect gene expression and genome stability via proteins that recognize and act upon such modifications. Many enzymes that catalyse epigenetic modifications or are critical for enzymatic complexes have been discovered, and this is encouraging investigators to study the role of these proteins in diverse normal and pathological processes. Rapidly growing knowledge in the area has resulted in the need for a resource that compiles, organizes and presents curated information to the researchers in an easily accessible and user-friendly form. Here we present EpiFactors, a manually curated database providing information about epigenetic regulators, their complexes, targets and products. EpiFactors contains information on 815 proteins, including 95 histones and protamines. For 789 of these genes, we include expressions values across several samples, in particular a collection of 458 human primary cell samples (for approximately 200 cell types, in many cases from three individual donors), covering most mammalian cell steady states, 255 different cancer cell lines (representing approximately 150 cancer subtypes) and 134 human postmortem tissues. Expression values were obtained by the FANTOM5 consortium using Cap Analysis of Gene Expression technique. EpiFactors also contains information on 69 protein complexes that are involved in epigenetic regulation. The resource is practical for a wide range of users, including biologists, pharmacologists and clinicians

Thermophotovoltaic Cells on Zinc Diffused Polycrystalline GaSb

For the first time, it has been demonstrated that thermophotovoltaic cells made of polycrystalline GaSb with small grain sizes (down to 100 x 100 {micro}m) have similar characteristics to the best Zinc diffused single crystal GaSb cells with identified device parameters. The grain boundaries in polycrystalline GaSb do not degrade TPV cell parameters, indicating that such material can be used for high-efficiency thermophotovoltaic cells

Blended Antilock Braking System Control Method for All-Wheel Drive Electric Sport Utility Vehicle

At least two different actuators work in cooperation in regenerative braking for electric and hybrid vehicles. Torque blending is an important area, which is responsible for better manoeuvrability, reduced braking distance, improved riding comfort, etc. In this paper, a control method for electric vehicle blended antilock braking system based on fuzzy logic is promoted. The principle prioritizes usage of electric motor actuators to maximize recuperation energy during deceleration process. Moreover, for supreme efficiency it considers the batteryâs state of charge for switching between electric motor and conventional electrohydraulic brakes. To demonstrate the functionality of the controller under changing dynamic conditions, a hardware-in-the-loop simulation with real electrohydraulic brakes test bed is utilized. In particular, the experiment is designed to exceed the state-of-charge threshold during braking operation, what leads to immediate switch between regenerative and friction brake modes. Document type: Part of book or chapter of boo

Plant expression, lyophilisation and storage of HBV medium and large surface antigens for a prototype oral vaccine formulation

Current immunisation programmes against hepatitis B virus (HBV) increasingly often involve novel tri-component vaccines containing—together with the small (S-HBsAg)—also medium and large surface antigens of HBV (M- and L-HBsAg). Plants producing all HBsAg proteins can be a source of components for a potential oral ‘triple’ anti-HBV vaccine. The objective of the presented research was to study the potential of M/L-HBsAg expression in leaf tissue and conditions of its processing for a prototype oral vaccine. Tobacco and lettuce carrying M- or L-HBsAg genes and resistant to the herbicide glufosinate were engineered and integration of the transgenes was verified by PCR and Southern hybridizations. M- and L-HBsAg expression was confirmed by Western blot and assayed by ELISA at the level of micrograms per g of fresh weight. The antigens displayed a common S domain and characteristic domains preS2 and preS1 and were assembled into virus-like particles (VLPs). Leaf tissues containing M- and L-HBsAg were lyophilised to produce a starting material of an orally administered vaccine formula. The antigens were distinctly sensitive to freeze-drying conditions and storage temperature, in the aspect of stability of S and preS domains and formation of multimeric particles. Efficiency of lyophilisation and storage depended also on the initial antigen content in plant tissue, yet M-HBsAg appeared to be approximately 1.5–2 times more stable than L-HBsAg. The results of the study provide indications concerning the preparation of two other constituents, next to S-HBsAg, for a plant-derived prototype oral tri-component vaccine against hepatitis B