Distributed Protocols at the Rescue for Trustworthy Online Voting

While online services emerge in all areas of life, the voting procedure in many democracies remains paper-based as the security of current online voting technology is highly disputed. We address the issue of trustworthy online voting protocols and recall therefore their security concepts with its trust assumptions. Inspired by the Bitcoin protocol, the prospects of distributed online voting protocols are analysed. No trusted authority is assumed to ensure ballot secrecy. Further, the integrity of the voting is enforced by all voters themselves and without a weakest link, the protocol becomes more robust. We introduce a taxonomy of notions of distribution in online voting protocols that we apply on selected online voting protocols. Accordingly, blockchain-based protocols seem to be promising for online voting due to their similarity with paper-based protocols

Lower bounds on the class number of algebraic function fields defined over any finite field

We give lower bounds on the number of effective divisors of degree $\leq g-1$ with respect to the number of places of certain degrees of an algebraic function field of genus $g$ defined over a finite field. We deduce lower bounds and asymptotics for the class number, depending mainly on the number of places of a certain degree. We give examples of towers of algebraic function fields having a large class number.Comment: 24 page

Espace déictique, espace syntaxique et prédication : les indices spatiaux du wolof

International audienceLe wolof possède un triplet d'indices de détermination par rapport à l'espace du locuteur : -i (proximité), -a (éloignement), -u (indétermination spatiale). Ces indices spatiaux traversent l'ensemble du système de la langue car qu'ils apparaissent à la fois dans la formation des déterminants définis du nom, dans celle de morphèmes subordonnants (pronoms relatifs, pronoms interrogatifs, connecteur “génitif”, conjonctions à valeur hypothétique et temporelle) mais aussi dans la formation de conjugaisons et de suffixes verbaux. On montrera que l'on peut rendre compte des emplois transcatégoriels de ces indices spatiaux, à l'aide des notions de situation d'énonciation, d'anaphore situationnelle, de portée syntaxique et de fonctionnement fractal. Le fonctionnement de ces morphèmes spatiaux revèle ainsi des liens organiques entre l'organisation dans l'espace déictique et l'organisation des relations dans l'espace syntaxique, autrement dit, entre l'espace du locuteur et les relations abstraites de détermination et de prédicatio

Polygrammaticalisation, grammaire fractale et propriétés d'échelle

La grammaticalisation est généralement étudiée comme un processus diachronique. On s'intéresse, dans cet article, aux morphèmes qui fonctionnent en synchronie dans différentes catégories syntaxiques et que l'on désigne comme des « marqueurs transcatégoriels ». Pour rendre compte du fonctionnement spécifique de ces termes, caractérisé par une variation de portée à la fois sémantique et syntaxique, on propose un modèle dynamique d'analyse, la “grammaire fractale”, qui se définit par deux mécanismes fondamentaux : la construction d'une forme schématique invariante, qui rend compte de l'unité du terme, et l'activation de propriétés d'échelles, qui rend compte de la variation sémantique et syntaxique. Cette analyse est illustrée par des exemples pris dans différentes langues

Inference of plasmid copy number mean and noise from single cell gene expression data

Plasmids are extra-chromosomal DNA molecules which code for their own replication. We previously reported a setup using genes coding for fluorescent proteins of two colors that allowed us, using a simple model, to extract the plasmid copy number noise in a monoclonal population of bacteria [J. Wong Ng et al., Phys. Rev. E, 81, 011909 (2010)]. Here we present a detailed calculation relating this noise to the measured levels of fluorescence, taking into account all sources of fluorescence fluctuations: the fluctuation of gene expression as in the simple model, but also the growth and division of bacteria, the non-uniform distribution of their ages, the random partition of proteins at divisions and the replication and partition of plasmids and chromosome. We show how using the chromosome as a reference helps extracting the plasmid copy number noise in a self-consistent manner.Comment: 9 pages, 3 figures, 2 table

Synthesis by sol–gel route of oxyapatite powders for dense ceramics : applications as electrolytes for solid oxide fuel cells

Solid oxide fuel cells have considerable interest in recent years, because of their high efficiency and environmentally friendly nature. Such systems required oxygen-conducting electrolytes and now the most common electrolyte is yttria stabilized zirconia (YSZ). This compound exhibits high oxide ion conductivity at elevated temperatures (850–1000 °C). However, this high working temperature causes problems in terms of materials selection and lifetime. One solution is to develop new oxide ions conductors exhibiting high oxide ion conductivity at intermediary temperatures (700–800 °C). Recent work has identified Ln10−xSi6O26±z (Ln = rare earths) as a good fast oxide ion conductor. Undoped and doped Ln10−xB6O26±z (B = Si or Ge) oxides are currently prepared by solid-state methods. In that work, we propose a sol–gel process to synthesize powders of La9.33Si6O26 type-silicated apatites. The main advantage is to decrease the crystallization temperature in ,comparison to the conventional methods, allowing the synthesis of reactive powders with nanometric particles size. These oxides are synthesized using silicon alkoxide and lanthanum nitride as precursors. In the litterature, no study refers to the synthesis of mixed oxides with silicon alcoxides. However, there are several studies on sol–gel synthesis of glasses with this precursor. In this study, several processing parameters have been investigated (the hydrolysis ratio, the concentration of metallic precursors in the sol and the role of organic compounds) in order to synthesize pure phases after the decomposition of the sols. Pure powders of La9.33Si6O26 type-silicated apatites are obtained at 800 °C. These powders were used to prepare ceramics. Several processing parameters as morphology of powders (agglomeration, particle sizes) and, heating profiles have been studied on the densification. Dense ceramics (90–95%) have been prepared at temperatures around 1400 °C. The used of sol–gel powders allow the decrease of the sintering temperature of about 200 °C

Assessing the factors behind oil price changes

The rapid rise in the price of crude oil between 2004 and the summer of 2006 are the subject of debate. This paper investigates the factors that might have contributed to the oil price increase in addition to demand and supply for crude oil, by expanding a model for crude oil prices to include refinery utilization rates, a non-linear effect of OPEC capacity utilization, and conditions in futures markets as explanatory variables. Together, these factors allow the model to perform well relative to forecasts implied by the far month contracts on the New York Mercantile Exchange and are able to account for much of the rise in crude oil prices between 2004 and 2006. JEL Classification: C53, Q41Oil prices, OPEC, Refinery industry

Remarks on low weight codewords of generalized affine and projective Reed-Muller codes

We propose new results on low weight codewords of affine and projective generalized Reed-Muller codes. In the affine case we prove that if the size of the working finite field is large compared to the degree of the code, the low weight codewords are products of affine functions. Then in the general case we study some types of codewords and prove that they cannot be second, thirds or fourth weight depending on the hypothesis. In the projective case the second distance of generalized Reed-Muller codes is estimated, namely a lower bound and an upper bound of this weight are given.Comment: New version taking into account recent results from Elodie Leducq on the characterization of the next-to-minimal codewords (cf. arXiv:1203.5244