Multi-locus analysis of genomic time series data from experimental evolution.

Genomic time series data generated by evolve-and-resequence (E&R) experiments offer a powerful window into the mechanisms that drive evolution. However, standard population genetic inference procedures do not account for sampling serially over time, and new methods are needed to make full use of modern experimental evolution data. To address this problem, we develop a Gaussian process approximation to the multi-locus Wright-Fisher process with selection over a time course of tens of generations. The mean and covariance structure of the Gaussian process are obtained by computing the corresponding moments in discrete-time Wright-Fisher models conditioned on the presence of a linked selected site. This enables our method to account for the effects of linkage and selection, both along the genome and across sampled time points, in an approximate but principled manner. We first use simulated data to demonstrate the power of our method to correctly detect, locate and estimate the fitness of a selected allele from among several linked sites. We study how this power changes for different values of selection strength, initial haplotypic diversity, population size, sampling frequency, experimental duration, number of replicates, and sequencing coverage depth. In addition to providing quantitative estimates of selection parameters from experimental evolution data, our model can be used by practitioners to design E&R experiments with requisite power. We also explore how our likelihood-based approach can be used to infer other model parameters, including effective population size and recombination rate. Then, we apply our method to analyze genome-wide data from a real E&R experiment designed to study the adaptation of D. melanogaster to a new laboratory environment with alternating cold and hot temperatures

A contribution for the development of new resources selection models for the agile/virtual enterprises

The process of resources systems selection, takes an important part in Agile / Virtual Enterprises (A/V E) integration because the efficient resources selection, or resources systems selection, running in useful time and cost and with efficient solution, is an important operation within the A/V E design phase and certainly will contribute for the flexibility of an A/V E within the phase of its reconfiguration. The resources systems selection is a difficult matter to solve in A/V E because: it can be of exponential complexity resolution; it can be a multi criteria problem; and because there are different types of A/V Es with different requirements that have originate the creation of a specific resources selection model for each one of them. This kind of selection approach models will be reviewed from literature and analyzed its limitations and the consequent necessities of development new ones. At the first time we identified necessities that never were thought before, like performance measures for the selection model, and the necessities of identifying the sponsor for the selection process. We will see too that the models fit uniquely the requirements of a unique A/V E are rigid and not flexible enough to satisfy the requirements of another A/V E. These limitations that we highlight in this work are important to be considered in the development of new models and were simultaneously considered in the development of our selection model for the project of the BM_Virtual Enterprise.info:eu-repo/semantics/publishedVersio

When Social Influence Meets Item Inference

Research issues and data mining techniques for product recommendation and viral marketing have been widely studied. Existing works on seed selection in social networks do not take into account the effect of product recommendations in e-commerce stores. In this paper, we investigate the seed selection problem for viral marketing that considers both effects of social influence and item inference (for product recommendation). We develop a new model, Social Item Graph (SIG), that captures both effects in form of hyperedges. Accordingly, we formulate a seed selection problem, called Social Item Maximization Problem (SIMP), and prove the hardness of SIMP. We design an efficient algorithm with performance guarantee, called Hyperedge-Aware Greedy (HAG), for SIMP and develop a new index structure, called SIG-index, to accelerate the computation of diffusion process in HAG. Moreover, to construct realistic SIG models for SIMP, we develop a statistical inference based framework to learn the weights of hyperedges from data. Finally, we perform a comprehensive evaluation on our proposals with various baselines. Experimental result validates our ideas and demonstrates the effectiveness and efficiency of the proposed model and algorithms over baselines.Comment: 12 page

Three-nucleon mechanisms in photoreactions

The $^{12}$C$(\gamma,ppn)$ reaction has been measured for E$_{\gamma}$=150-800 MeV in the first study of this reaction in a target heavier than $^3$He. The experimental data are compared to a microscopic many body calculation. The model, which predicts that the largest contribution to the reaction arises from final state interactions following an initial pion production process, overestimates the measured cross sections and there are strong indications that the overestimate arises in this two-step process. The selection of suitable kinematic conditions strongly suppresses this two-step contribution leaving cross sections in which up to half the yield is predicted to arise from the absorption of the photon on three interacting nucleons and which agree with the model. The results indicate $(\gamma,3N)$ measurements on nuclei may be a valuable tool for obtaining information on the nuclear three-body interaction.Comment: 5 pages, 3 figure

Domain of applicability of Value Analysis approach in the pre-selection of resources

For the project of an Agile/Virtual Enterprise (A/V E) the resources selection is a key factor. The output of the selection process should be prepared to guarantee quality, efficiency and cost-attractiveness, in order to ensure the agility and integrability of the A/V E. Despite the potential of Value Analysis (VA), none of the resources selection models found in the literature incorporates the VA integration. The main objective is to quantify the selection process performance with VA integrated into the pre-selection of resources in accordance with the developed model. The paper presents through the simulation results analysis, some of the benefits of VA application: greater applicability domain for candidate resources and number of tasks; and reduction of the selection time.info:eu-repo/semantics/publishedVersio

Search for Yukawa Production of a Light Neutral Higgs Boson at LEP

Within a Two-Higgs-Doublet Model (2HDM) a search for a light Higgs boson in the mass range of 4-12 GeV has been performed in the Yukawa process e+e- -> b bbar A/h -> b bbar tau+tau-, using the data collected by the OPAL detector at LEP between 1992 and 1995 in e+e- collisions at about 91 GeV centre-of-mass energy. A likelihood selection is applied to separate background and signal. The number of observed events is in good agreement with the expected background. Within a CP-conserving 2HDM type II model the cross-section for Yukawa production depends on xiAd = |tan beta| and xihd = |sin alpha/cos beta| for the production of the CP-odd A and the CP-even h, respectively, where tan beta is the ratio of the vacuum expectation values of the Higgs doublets and alpha is the mixing angle between the neutral CP-even Higgs bosons. From our data 95% C.L. upper limits are derived for xiAd within the range of 8.5 to 13.6 and for xihd between 8.2 to 13.7, depending on the mass of the Higgs boson, assuming a branching fraction into tau+tau- of 100%. An interpretation of the limits within a 2HDM type II model with Standard Model particle content is given. These results impose constraints on several models that have been proposed to explain the recent BNL measurement of the muon anomalous magnetic moment.Comment: 24 pages, 9 figures, Submitted to Euro. Phys. J.

Integração de análise do valor no processo de configuração de empresas ágeis / virtuais

Tese de doutoramento Engenharia Industrial e de SistemasCom a crescente globalização dos mercados é fundamental as empresas apostarem na inovação, competitividade e excelência. É importante a criação de uma cultura de valor nas empresas, através de métodos como a Análise do Valor (AV). Cada vez mais, um produto/serviço é produzido/prestado com a contribuição de várias empresas, pelo que surgiu e desenvolveu-se o conceito de Empresas Ágeis/Virtuais (E A/V). No âmbito deste trabalho de Doutoramento é proposta a integração da AV no processo de configuração de E A/V, segundo o modelo referencial BM_VEARM, com o objectivo de demonstrar que esta integração incorpora mais-valias qualitativas e quantitativas em todo o processo global de selecção de recursos. Efectuou-se uma revisão sobre o estado da arte da AV e suas potencialidades e desenvolveu-se uma análise global sobre o processo de selecção de recursos em empresas convencionais e especialmente nos modelos existentes de selecção de recursos em E A/V. Foram identificadas as suas lacunas, de forma a potenciar a construção de um novo modelo, demonstrando que os objectivos do trabalho se enquadravam nas necessidades de investigação. Foi desenvolvido um modelo rigoroso e abrangente de integração da AV na etapa de negociação indirecta da fase de pré-selecção de recursos de modo a aferir a sua aplicabilidade e seus potenciais benefícios nas E A/V. Este modelo foi representado em linguagem IDEF0. Foram definidas novas actividades para esta fase e criaram-se novos sistemas de requisitos de pré-selecção. Foi efectuado um estudo empírico em empresas, de forma a reforçar a validação de alguns dos pressupostos do modelo com dados reais. Desenvolveu-se um demonstrador numérico, com base no modelo proposto. Este demonstrador permitiu simular o processo de pré-selecção de recursos e consequente selecção final com e sem aplicação do modelo de integração da AV através de avaliação dos recursos candidatos. Com as simulações efectuadas pelo demonstrador e respectiva análise dos resultados, conseguimos validar que a aplicação do nosso modelo conduz a um sistema final de recursos seleccionados em que se obtém uma série de vantagens que passamos a enumerar: • Maior valor do sistema de recursos seleccionado, assegurando que todos os recursos seleccionados obtêm um valor positivo nos sistemas considerados; • Maior eficiência do processo de selecção de recursos com redução do tempo de processamento da selecção; • Maior eficácia do processo de selecção de recursos, com um maior domínio de tarefas processadas para o mesmo número de recursos candidatos; • Desenvolvimento de uma abordagem sistemática e organizada para o processo de pré-selecção; • Abrangência do modelo, consoante as especificidades de cada projecto de E A/V.The markets globalization requires companies to continually invest in innovation, competitiveness and excellence. It is important to create a value culture in companies, through methods such as Value Analysis (VA). Currently a product / service is often produced with contributions from several companies, and the concept of Agile / Virtual Enterprises (A/V E) emerged and developed. In this PhD work, the author propose the VA integration in the configuration process of A/V E, according to the reference model BM_VEARM, with the main objective of demonstrate that this integration incorporates qualitative and quantitative advantages throughout the whole resources selection process. A literature review is made on the state of the art of VA and its potentialities and it was made a global analysis of the resources selection process in conventional companies and especially in the existing resources selection models for A/V E. The gaps of the problem were identified, in order to strengthen the creation of a new model, showing that the work objectives fit the research needs. We built a rigorous and comprehensive model of VA integration in the stage of indirect negotiation in resources pre-selection in order to assess its applicability and its potential benefits in A/V E. This model was represented in IDEF0 language. New activities have been defined for this phase and we created new systems requirements for pre-selection. It was conducted an empirical study in companies, in order to increase the validation of some model assumptions with actual data. A numerical demonstrator was built, based on the proposed model. This demonstrator allowed simulating the resources pre-selection process and consequent final selection with and without application of the VA integration model through the evaluation of the candidate resources. With the simulations made by the demonstrator and its results analysis, it was validated that the application of our model leads to a final resources system in which we obtained a number of advantages that we list: • Higher value of the selected resources systems ensuring that all selected resources get a positive value in the systems considered. • Increased efficiency of the resources selection process with reduction of the processing time of the selection. • Greater efficacy of the resources selection process, with a larger domain of tasks processed for the same number of candidate resources; • Development of a systematic and organized approach for the pre-selection process; • Rigorous and comprehensive model, according to the specifics of each A/V E project

Rural Telecommunications Infrastructure Selection Using the Analytic Network Process.

The decisions involved in rural settings are of complex nature, with some aspects compounded by the presence of intangible criteria. Hence, a suitable approach is needed that can produce effective solutions. This paper describes the applicability of a multicriteria decision-making method, specifically the analytic network process (ANP), to model the selection of an appropriate telecommunications infrastructure technology, capable of deploying e-services in rural areas of developing countries. It aims to raise awareness among telecommunication planners about the availability of ANP, and to demonstrate its suitability to enhance the selection process. The proposed model is constructed based on concerned experts' views of relevant selection criteria and potential technology alternatives. Its network structure caters for all possible dependencies and interactions among criteria and alternatives