Search results for "calculu"
showing 10 items of 642 documents
Semiotica e Matematiche: un'introduzione
2014
The foundations of Peircean's and Saussurean's Semiotics itself is centered on two mathematical ideas coming from differential calculus and theory of continuity. Other mathematical ideas can be founded in some of the most important ideas in Semiotics. The papers investigates the relationships between Mathematics and Semiotics in both a historical and theoretical way.
Intrinsic challenges in ancient microbiome reconstruction using 16S rRNA gene amplification
2015
AbstractTo date, characterization of ancient oral (dental calculus) and gut (coprolite) microbiota has been primarily accomplished through a metataxonomic approach involving targeted amplification of one or more variable regions in the 16S rRNA gene. Specifically, the V3 region (E. coli 341–534) of this gene has been suggested as an excellent candidate for ancient DNA amplification and microbial community reconstruction. However, in practice this metataxonomic approach often produces highly skewed taxonomic frequency data. In this study, we use non-targeted (shotgun metagenomics) sequencing methods to better understand skewed microbial profiles observed in four ancient dental calculus speci…
Transforming RNA-Seq Data to Improve the Performance of Prognostic Gene Signatures
2014
Gene expression measurements have successfully been used for building prognostic signatures, i.e for identifying a short list of important genes that can predict patient outcome. Mostly microarray measurements have been considered, and there is little advice available for building multivariable risk prediction models from RNA-Seq data. We specifically consider penalized regression techniques, such as the lasso and componentwise boosting, which can simultaneously consider all measurements and provide both, multivariable regression models for prediction and automated variable selection. However, they might be affected by the typical skewness, mean-variance-dependency or extreme values of RNA-…
Dental calculus evidence of Taï Forest Chimpanzee plant consumption and life history transitions
2015
AbstractDental calculus (calcified dental plaque) is a source of multiple types of data on life history. Recent research has targeted the plant microremains preserved in this mineralised deposit as a source of dietary and health information for recent and past populations. However, it is unclear to what extent we can interpret behaviour from microremains. Few studies to date have directly compared the microremain record from dental calculus to dietary records and none with long-term observation dietary records, thus limiting how we can interpret diet, food acquisition and behaviour. Here we present a high-resolution analysis of calculus microremains from wild chimpanzees (Pan troglodytes ve…
The Bronze Age burials from Cova Dels Blaus (Vall d′Uixó, Castelló, Spain): An approach to palaeodietary reconstruction through dental pathology, occ…
2005
This paper reports a palaeodietary investigation of the human remains found in the collective Bronze Age burial cave from Vall d'Uixó (Castelló, Spain). Dental pathology, tooth wear as well as buccal dental microwear were analysed. Percentages of dental pathologies were compared with Chalcolithic and Bronze Age sites from the same territory. Dental caries, ante-mortem tooth loss, periodontal disease and abscess frequencies indicate a diet rich in carbohydrate foods. However, dental calculus percentages and macroscopic wear patterns suggest a diet not exclusively relying on agricultural resources. In addition, buccal dental microwear density and length by orientation recorded on micrographs …
Empirical study of the dependence of the results of multivariable flexible survival analyses on model selection strategy
2008
Flexible survival models, which avoid assumptions about hazards proportionality (PH) or linearity of continuous covariates effects, bring the issues of model selection to a new level of complexity. Each ‘candidate covariate’ requires inter-dependent decisions regarding (i) its inclusion in the model, and representation of its effects on the log hazard as (ii) either constant over time or time-dependent (TD) and, for continuous covariates, (iii) either loglinear or non-loglinear (NL). Moreover, ‘optimal’ decisions for one covariate depend on the decisions regarding others. Thus, some efficient model-building strategy is necessary. We carried out an empirical study of the impact of the model …
Some approximation properties of ( p , q ) $(p,q)$ -Bernstein operators
2016
This paper is concerned with the $(p,q)$ -analog of Bernstein operators. It is proved that, when the function is convex, the $(p,q)$ -Bernstein operators are monotonic decreasing, as in the classical case. Also, some numerical examples based on Maple algorithms that verify these properties are considered. A global approximation theorem by means of the Ditzian-Totik modulus of smoothness and a Voronovskaja type theorem are proved.
Stationary and non-stationary stochastic response of linear fractional viscoelastic systems
2012
Abstract A method is presented to compute the stochastic response of single-degree-of-freedom (SDOF) structural systems with fractional derivative damping, subjected to stationary and non-stationary inputs. Based on a few manipulations involving an appropriate change of variable and a discretization of the fractional derivative operator, the equation of motion is reverted to a set of coupled linear equations involving additional degrees of freedom, the number of which depends on the discretization of the fractional derivative operator. As a result of the proposed variable transformation and discretization, the stochastic analysis becomes very straightforward and simple since, based on stand…
Le martingale: aspetti teorici ed applicativi
2001
This paper offers an overview on the characteristics of martingales. These latter are markovian processes without underlying trend, in which the stochastic variable depends on its ultimate realisation. Some application fields are in studies relative to financial markets, and especially the derivative securities. Drawing from the theoretical and empirical literature, the main mathematical characteristics are presented. In order to transform processes with increasing or decreasing trends into martingales, the Doob-Meyer decomposition and the change of probability measure approaches can be adopted. Finally, four applications are considered with regard to the pricing of futures, call options an…