GRAPHICAL REPRESENTATION OF TRANSACTION ARRANGEMENTS

With this article the intention is to add to the Transaction Cost Analysis empirical discussions. It introduces a model that aims to graphically represent transaction arrangements. The proposed model was empirically tested in the Brazilian fruit export sector. Six different fruit were used as the basis for the investigation: melons, grapes, mangoes, papayas, oranges and apples. These are the six most exported fruit produced in Brazil. Two distinct research techniques were used in the investigation: secondary data analysis and interviews. The focal aim of the secondary data research was the characterisation and comparison of the production and export sequences of the six most exported Brazilian fruit types. The content of the semi-structured interview questions was determined based on the literature review of Transaction Cost Analysis and the international fruit trade. The questions were carefully chosen to reveal the factors which are determinant for the configuration of transaction arrangements in the fruit trade. The Graphical Representation of Transactions successfully disclosed the three main types of arrangements used by Brazilian fruit exporters. These arrangements are: Integrated Production-Export Transaction Arrangement, Export Agents Transaction Arrangement and the Integrated Multinational Transaction Arrangement. The graphical model makes the process of categorising organisations according to their behaviour more precise. By clearly describing the technical activities performed by an organisation it is possible to assess its role in a specific sector.transaction costs, fruit trade, graphical representation., Crop Production/Industries,

Distributed, adaptive deployment for nonholonomic mobile sensor networks : theory and experiments

In this work we show the Lyapunov stability and convergence of an adaptive and decentralized coverage control for a team of mobile sensors. This new approach assumes nonholonomic sensors rather than the usual holonomic sensors found in the literature. The kinematics of the unicycle model and a nonlinear control law in polar coordinates are used in order to prove the stability of the controller applied over a team of mobile sensors. This controller is adaptive, which means that the mobile sensors are able to estimate and map a density function in the sampling space without a previous knowledge of the environment. The controller is decentralized, which means that each mobile sensor has its own estimate and computes its own control input based on local information. In order to guarantee the estimate convergence, the mobile sensors implement a consensus protocol in continuous time assuming a fixed network topology and zero communication delays. The convergence and feasibility of the coverage control algorithm are verified through simulations in Matlab and Stage. The Matlab simulations consider only the kinematics of the mobile sensors and the Stage simulations consider the dynamics and the kinematics of the sensors. The Matlab simulations show successful results since the sensor network carries out the coverage task and distributes itself over the estimated density function. The adaptive law which is defined by a differential equation must be approximated by a difference equation to be implementable in Stage. The Stage simulations show positive results, however, the system is not able to achieve an accurate estimation of the density function. In spite of that, the sensors carry out the coverage task distributing themselves over the sampling space. Furthermore, some experiments are carried out using a team of four Pioneer 3-AT robots sensing a piecewise constant light distribution function. The experimental results are satisfactory since the robots carry out the coverage task. However, the accuracy of the estimation is affected by the approximation of the adaptation law by difference equations, the number of robots and sensor sensitivity. Based on the results of this research, the decentralized adaptive coverage control for nonholonomic vehicles has been analyzed from a theoretical approach and validated through simulation and experimentation with positive results. As a future work we will investigate: (i) new techniques to improve the implementation of the adaptive law in real time,(ii) the consideration of the dynamics of the mobile sensors, and (iii) the stability and convergence of the adaptive law for continuous-time variant density function

Optimization and Regulation of Performance for Computing Systems

The current demands of computing applications, the advent of technological advances related to hardware and software, the contractual relationship between users and cloud service providers and current ecological demands, require the re\ufb01nement of performance regulation on computing systems. Powerful mathematical tools such as control systems theory, discrete event systems (DES) and randomized algorithms (RAs) have o\ufb00ered improvements in e\ufb03ciency and performance in computer scenarios where the traditional approach has been the application of well founded common sense and heuristics. The comprehensive concept of computing systems is equally related to a microprocessor unit, a set of microprocessor units in a server, a set of servers interconnected in a data center or even a network of data centers forming a cloud of virtual resources. In this dissertation, we explore theoretical approaches in order to optimize and regulate performance measures in di\ufb00erent computing systems. In several cases, such as cloud services, this optimization would allow the fair negotiation of service level agreements (SLAs) between a user and a cloud service provider, that may be objectively measured for the bene\ufb01t of both negotiators. Although DES are known to be suitable for modeling computing systems, we still \ufb01nd that traditional control theory approaches, such as passivity analysis, may o\ufb00er solutions that are worth being explored. Moreover, as the size of the problem increases, so does its complexity. RAs o\ufb00er good alternatives to make decisions on the design of the solutions of such complex problems based on given values of con\ufb01dence and accuracy. In this dissertation, we propose the development of: a) a methodology to optimize performance on a many-core processor system, b) a methodology to optimize and regulate performance on a multitier server, c) some corrections to a previously proposed passivity analysis of a market-oriented cloud model, and d) a decentralized methodology to optimize cloud performance. In all the aforementioned systems, we are interested in developing optimization methods strongly supported on DES theory, speci\ufb01cally In\ufb01nitesimal Perturbation Analysis (IPA) and RAs based on sample complexity to guarantee that these computing systems will satisfy the required optimal performance on the average

Genetic diversity of peanut (Arachis hypogaea L.) and its wild relatives based on the analysis of hypervariable regions of the genome

BACKGROUND: The genus Arachis is native to a region that includes Central Brazil and neighboring countries. Little is known about the genetic variability of the Brazilian cultivated peanut (Arachis hypogaea, genome AABB) germplasm collection at the DNA level. The understanding of the genetic diversity of cultivated and wild species of peanut (Arachis spp.) is essential to develop strategies of collection, conservation and use of the germplasm in variety development. The identity of the ancestor progenitor species of cultivated peanut has also been of great interest. Several species have been suggested as putative AA and BB genome donors to allotetraploid A. hypogaea. Microsatellite or SSR (Simple Sequence Repeat) markers are co-dominant, multiallelic, and highly polymorphic genetic markers, appropriate for genetic diversity studies. Microsatellite markers may also, to some extent, support phylogenetic inferences. Here we report the use of a set of microsatellite markers, including newly developed ones, for phylogenetic inferences and the analysis of genetic variation of accessions of A. hypogea and its wild relatives. RESULTS: A total of 67 new microsatellite markers (mainly TTG motif) were developed for Arachis. Only three of these markers, however, were polymorphic in cultivated peanut. These three new markers plus five other markers characterized previously were evaluated for number of alleles per locus and gene diversity using 60 accessions of A. hypogaea. Genetic relationships among these 60 accessions and a sample of 36 wild accessions representative of section Arachis were estimated using allelic variation observed in a selected set of 12 SSR markers. Results showed that the Brazilian peanut germplasm collection has considerable levels of genetic diversity detected by SSR markers. Similarity groups for A. hypogaea accessions were established, which is a useful criteria for selecting parental plants for crop improvement. Microsatellite marker transferability was up to 76% for species of the section Arachis, but only 45% for species from the other eight Arachis sections tested. A new marker (Ah-041) presented a 100% transferability and could be used to classify the peanut accessions in AA and non-AA genome carriers. CONCLUSION: The level of polymorphism observed among accessions of A. hypogaea analyzed with newly developed microsatellite markers was low, corroborating the accumulated data which show that cultivated peanut presents a relatively reduced variation at the DNA level. A selected panel of SSR markers allowed the classification of A. hypogaea accessions into two major groups. The identification of similarity groups will be useful for the selection of parental plants to be used in breeding programs. Marker transferability is relatively high between accessions of section Arachis. The possibility of using microsatellite markers developed for one species in genetic evaluation of other species greatly reduces the cost of the analysis, since the development of microsatellite markers is still expensive and time consuming. The SSR markers developed in this study could be very useful for genetic analysis of wild species of Arachis, including comparative genome mapping, population genetic structure and phylogenetic inferences among species

CONFIGURAÇÃO DE TRANSAÇÕES INTERNACIONAL: CARNE BOVINA TOCANTINENSE COM DESTINO AO MERCADO RUSSO

Este artigo mostra as principais configurações de transações comerciais empregadas por atores comerciais internacionais envolvidos nas transações de carne bovina tocantinense com destino ao mercado russo. Com este objetivo, o artigo descreve as principais atividades técnicas executadas pelas firmas envolvidas nas configurações de transações encontradas a fim entregar seu produto. São descritos também os tipos principais de organizações, os atores atuantes no negócio da carne bovina e as operações comerciais. As múltiplas configurações de transações usadas pelas organizações e pelos diferentes atores são apresentadas usando o modelo de representação gráfico. --------------------------------------------This paper shows the main commercial transaction configurations employed by actors involved in international transactions of bovine meat produced in Tocantins State and destined to the Russian market. With this aim, the paper describes the main technical activities performed by each organization involved in the trade. The multiple configurations of transactions used by organizations and the actors are presented using the graphical representation model.Custos de Transação, Representação Gráfica, Comércio de Carne Bovina, Comércio Internacional, Cattle Trade of Bovine Meat, Transaction Costs, Graphical Representation of Transactions, International Trade, International Relations/Trade, Livestock Production/Industries,

CONFIGURAÇÕES DE TRANSAÇÃO DA CADEIA DE PRODUÇÃO E COMÉRCIO DO ÁLCOOL COMBUSTÍVEL: Estudo de Caso do Vale do São Patrício - GO

O setor sucroalcooleiro tem passado por mudanças nas suas atividades produtivas e comerciais devido a diversos fatores. Com a inserção das novas regras institucionais acirrouse a concorrência entre as usinas de álcool, obrigando-as a se organizarem para coordenar a produção e distribuição de álcool combustível de forma mais eficiente. O presente trabalho teve como objetivo identificar os modelos de transações utilizados pela agroindústria sucroalcooleira do Vale do São Patrício – GO, para gerir e disponibilizar o seu produto, sendo assim capaz de manter a unidade produtiva de álcool combustível estudada no mercado. A metodologia de pesquisa empregada foi estudo de caso e entrevistas com informantes chaves e discutida com base no modelo da representação gráfica. Como resultados foram levantados dezessete atividades técnicas necessárias para se produzir álcool combustível e os responsáveis pelo desempenho destas atividades. Identificaram-se duas configurações de transações predominantes e quais são os critérios de qualidade observados desde a produção à comercialização.--------------With the increase of competition in alcohol production business the production companies were forced to better organize and coordinate their activities. This study aims to identify the predominant model of alcohol production and trade. This research also had the objective to describe the main managerial principles employed at the alcohol production plants. As a research method is was employed case studies and interviews with key informants. It was found that there are 17 main technical activities that needed to be performed in order to produce and trade alcohol destined to be used as fuel. It was also possible to identify the categories of organizations that are responsible for each of these technical activities. Only two transaction configurations were found predominating in the sector.usina de álcool, configuração de transação, álcool combustível, qualidade, alcohol plant, transaction configuration, alcohol fuel, quality, Agribusiness,