Some inequalities for the Tutte polynomial

We prove that the Tutte polynomial of a coloopless paving matroid is convex along the portions of the line segments x+y=p lying in the positive quadrant. Every coloopless paving matroids is in the class of matroids which contain two disjoint bases or whose ground set is the union of two bases of M*. For this latter class we give a proof that T_M(a,a) <= max {T_M(2a,0), T_M(0,2a)} for a >= 2. We conjecture that T_M(1,1) <= max {T_M(2,0), T_M(0,2)} for the same class of matroids. We also prove this conjecture for some families of graphs and matroids.Comment: 17 page

Adiabaticity Conditions for Volatility Smile in Black-Scholes Pricing Model

Our derivation of the distribution function for future returns is based on the risk neutral approach which gives a functional dependence for the European call (put) option price, C(K), given the strike price, K, and the distribution function of the returns. We derive this distribution function using for C(K) a Black-Scholes (BS) expression with volatility in the form of a volatility smile. We show that this approach based on a volatility smile leads to relative minima for the distribution function ("bad" probabilities) never observed in real data and, in the worst cases, negative probabilities. We show that these undesirable effects can be eliminated by requiring "adiabatic" conditions on the volatility smile

A survey of free software for the design, analysis, modelling, and simulation of an unmanned aerial vehicle

The objective of this paper is to analyze free software for the design, analysis, modelling, and simulation of an unmanned aerial vehicle (UAV). Free software is the best choice when the reduction of production costs is necessary; nevertheless, the quality of free software may vary. This paper probably does not include all of the free software, but tries to describe or mention at least the most interesting programs. The first part of this paper summarizes the essential knowledge about UAVs, including the fundamentals of flight mechanics and aerodynamics, and the structure of a UAV system. The second section generally explains the modelling and simulation of a UAV. In the main section, more than 50 free programs for the design, analysis, modelling, and simulation of a UAV are described. Although the selection of the free software has been focused on small subsonic UAVs, the software can also be used for other categories of aircraft in some cases; e.g. for MAVs and large gliders. The applications with an historical importance are also included. Finally, the results of the analysis are evaluated and discussed—a block diagram of the free software is presented, possible connections between the programs are outlined, and future improvements of the free software are suggested. © 2015, CIMNE, Barcelona, Spain.Internal Grant Agency of Tomas Bata University in Zlin [IGA/FAI/2015/001, IGA/FAI/2014/006

Impact of missing participant data for dichotomous outcomes on pooled effect estimates in systematic reviews : a protocol for a methodological study

Abstract Background There is no consensus on how authors conducting meta-analysis should deal with trial participants with missing outcome data. The objectives of this study are to assess in Cochrane and non-Cochrane systematic reviews: (1) which categories of trial participants the systematic review authors consider as having missing participant data (MPD), (2) how trialists reported on participants with missing outcome data in trials, (3) whether systematic reviewer authors actually dealt with MPD in their meta-analyses of dichotomous outcomes consistently with their reported methods, and (4) the impact of different methods of dealing with MPD on pooled effect estimates in meta-analyses of dichotomous outcomes. Methods/Design We will conduct a methodological study of Cochrane and non-Cochrane systematic reviews. Eligible systematic reviews will include a group-level meta-analysis of a patient-important dichotomous efficacy outcome, with a statistically significant effect estimate. Teams of two reviewers will determine eligibility and subsequently extract information from each eligible systematic review in duplicate and independently, using standardized, pre-piloted forms. The teams will then use a similar process to extract information from the trials included in the meta-analyses of interest. We will assess first which categories of trial participants the systematic reviewers consider as having MPD. Second, we will assess how trialists reported on participants with missing outcome data in trials. Third, we will compare what systematic reviewers report having done, and what they actually did, in dealing with MPD in their meta-analysis. Fourth, we will conduct imputation studies to assess the effects of different methods of dealing with MPD on the pooled effect estimates of meta-analyses. We will specifically calculate for each method (1) the percentage of systematic reviews that lose statistical significance and (2) the mean change of effect estimates across systematic reviews. Discussion The impact of different methods of dealing with MPD on pooled effect estimates will help judge the associated risk of bias in systematic reviews. Our findings will inform recommendations regarding what assumptions for MPD should be used to test the robustness of meta-analytical results

Informe: Derecho del trabajo y de la seguridad social en España en 2013. Algunos puntos críticos

Este documento intenta reflejar algunos de los principales cambios y novedades del ordenamiento laboral español en 2013, levantando acta de cómo la mutabilidad de nuestro Derecho del Trabajo es imparable. Este informe, consciente de ello, ofrece una selección de elementos esenciales, a juicio de sus autores, especialistas en cada una de las materias, encuadrados en la Sección Juvenil de la Asociación Española de Derecho del Trabajo y de la Seguridad Social. En él, conforme a la organización de dicha Sección en grupos de trabajo, se abordan las novedades más relevantes en materia de derechos fundamentales inespecíficos, contratación laboral, vicisitudes del contrato de trabajo, Derecho colectivo, conciliación y corresponsabilidad, protección social y prevención de riesgos laborales. This paper tries to show some of the many changes and novelties in Spanish Labour Law during 2013, drawing up a record of the unstoppable character of our Labour legal system. This report offers a selection of essential elements, according to its authors, all of them specialists in each one of the subjects, being part of the Young Scholars’ Section of the Spanish Association for Labour and Social Security Law. According to the organization of the said Section in working groups, we can find novelties concerning unspecific fundamental rights, work contracts, the life of the work contract and collective Labour Law, reconciliation and co responsibility, social protection and occupational risk prevention

El derecho del trabajo y de la seguridad social en España en 2014

Este documento intenta reflejar algunos de los principales cambios y novedades del ordenamiento laboral español en 2014, levantando acta de cómo la mutabilidad de nuestro Derecho del Trabajo es imparable. Este informe, consciente de ello, ofrece una selección de elementos esenciales, a juicio de sus autores, especialistas en cada una de las materias, encuadrados en la Sección Juvenil de la Asociación Española de Derecho del Trabajo y de la Seguridad Social. En él, conforme a la organización de dicha Sección en grupos de trabajo, se abordan las novedades más relevantes en materia de derechos fundamentales inespecíficos, contratación laboral, vicisitudes del contrato de trabajo, Derecho colectivo, conciliación y corresponsabilidad, protección social y prevención de riesgos laborales. This paper tries to show some of the many changes and novelties in Spanish Labour Law during 2014, drawing up a record of the unstoppable character of our Labour legal system. This report offers a selection of essential elements, according to its authors, all of them specialists in each one of the subjects, being part of the Young Scholars’ Section of the Spanish Association for Labour and Social Security Law. According to the organization of the said Section in working groups, we can find novelties concerning unspecific fundamental rights, work contracts, the life of the work contract and collective Labour Law, work-life balance and co responsibility, social protection and occupational risk prevention

Dynamic Global Packet Routing in Wireless Networks

We consider schemes for reuse-efficient packet access in wireless data networks. We show that computing the maximum ergodic packet arrival rate is NPhard. We give an upper bound on the maximum ergodic throughput in terms of the eigenvalues of matrices related to the path-gain matrix. We present simple, practical heuristic algorithms which exhibit good throughput and packet delay and report on results of preliminary simulations. More sophisticated algorithms that yield optimal throughput are also presented. A recent result of McKeown, Anantharam and Walrand on scheduling of input-queued switches is obtained as a byproduct. 1. Introduction This paper addresses schemes for reuse-efficient transmission in wireless packet data networks. Particular attention is paid to recent proposals (see for example [19]) for wireless data packet networks in which the medium access (MAC) layer protocol is: (i) deterministically scheduled. (ii) has good delay performance. (iii) provides near-optimal ch..

Processor-Ring Communication: A Tight Asymptotic Bound on Packet Waiting Times

We consider N processors communicating unidirectionally over a closed transmission channel, or ring. Each message is assembled into a fixed-length packet. Packets to be sent are generated at random times by the processors, and the transit times spent by packets on the ring are also random. Packets being forwarded, i.e., packets already on the ring, have priority over waiting packets. The objective of this paper is to analyze packet waiting times under a greedy policy, within a discrete Markov model that retains the over-all structure of a practical system, but is simple enough so that explicit results can be proved. Independent, identical Bernoulli processes model message generation at the processors, and i.i.d. geometric random variables model the transit times. Our emphasis is on asymptotic behavior for large ring sizes, N , when the respective rate parameters have the scaling =N and ¯=N . Our main result shows that, if the traffic intensity is fixed at ae = =¯ ! 1, then as N !1 the ..