Fast Distributed Computation of Distances in Networks

This paper presents a distributed algorithm to simultaneously compute the diameter, radius and node eccentricity in all nodes of a synchronous network. Such topological information may be useful as input to configure other algorithms. Previous approaches have been modular, progressing in sequential phases using building blocks such as BFS tree construction, thus incurring longer executions than strictly required. We present an algorithm that, by timely propagation of available estimations, achieves a faster convergence to the correct values. We show local criteria for detecting convergence in each node. The algorithm avoids the creation of BFS trees and simply manipulates sets of node ids and hop counts. For the worst scenario of variable start times, each node i with eccentricity ecc(i) can compute: the node eccentricity in diam(G)+ecc(i)+2 rounds; the diameter in 2*diam(G)+ecc(i)+2 rounds; and the radius in diam(G)+ecc(i)+2*radius(G) rounds.Comment: 12 page

Combinatorial regulation of shared target genes by LMD and MEF2

The development of any multicellular organism involves the coordinated expression of different genes in complex spatio-temporal patterns. These complex patterns of gene expression result from the interplay between multiple transcription factors (TFs) and their co-factors, acting on specific cis-regulatory modules to activate or repress the affected locus. This study investigates the interaction between two essential regulators of myogenesis: the transcription factors Myocyte enhancing factor 2 (Mef2) and lame duck (lmd). Mutations in either of these transcription factors results in a similar block of fusion phenotype, but the molecular basis for this similar phenotype is not yet understood. The analysis started with ChIP-on-chip to identify the genomic location where each TF binds in vivo. Microarrays were used again to conduct expression profiling of loss-of-function mutants, and the combination of these two approaches yielded a list of direct target genes of the two TFs. Interestingly, the majority of enhancers bound by Lmd are also bound by Mef2 at the same developmental timepoint. Likewise, almost 80% of the lmd direct target genes are also direct targets of Mef2, revealing an extensive co-regulation between the two TFs. A group of shared direct targets was then selected for further study; Lmd and Mef2, alone or in combination, were used to drive ectopic expression of these genes, resulting in both synergistic and antagonistic interactions. The affected enhancer for each target was identified using a variety of predictions, and transgenic fly lines were created to demonstrate the capacity of the enhancers for correct expression in vivo. These enhancers were also analyzed in the mutant background of loss-of-function mutations and revealed specific requirements for each transcription factor. Lmd and Mef2 were also tested in vitro for their effect on transcription from these enhancers, revealing additive, cooperative, and repressive interactions. These results indicate that lmd is a temporal and tissue-specific modulator of Mef2 activity, acting both as a transcriptional activator and repressor on a sub- set of the catalog of target genes of Mef2. More generally, it demonstrates a scenario of flexibility in the regulatory output of two transcription factors, leading to additive, cooperative and repressive interactions

The limits and merits of participation

The goal of economic development is to increase growth and eliminate poverty. Recently, the goal has been broadened to include promoting participatory governance. Arguably, participation, for example, in community water committees, produces two desirable outcomes: democratic processes and better-targeted, more efficiently delivered public services. Participation is desirable as an end in itself, as a means of sharing resources, control, and responsibility within the social group. Yet participation is not always related to democracy. Fascism was a participatory, grassroots political movement. Participation is as much a problem as it is a solution, as much a goal as a tool. It is a problem when it is disorderly and if it is assumed to be a substitute for democratic representation. It is a solution when it changes conflict into negotiated losses. Participation can make development assistance more effective, but it works best for groups that are already participatory; for groups that can already help themselves. The recent literature on the effectiveness of foreign aid to developing countries presents an interesting analogy. Most foreign aid is useless. The only part that really helps development is that which follows rather than precedes policy change. Similarly, participation seems to work well only when the institutions of participation are in place before the need they address arises and when the institutions are compatible with the need s objectives. These conditions are not easily met. Discussions of participation cannot ignore issues of political power, local power, populism, and representation. They cannot ignore issues of moral pluralism (the verity of ways in which people value their lives) or cultural diversity. They cannot dismiss the ways in which people can be blocked from better lives by the beliefs of their cultures. They cannot avoid the pressure that a dominant group may exert to forgesolutions that are morally unacceptable. These problems are not irrelevant or unimportant. Efforts to promote participation would seem strikingly banal were the history of development efforts not replete with failures to achieve participation where it would have made a difference. It has typically been assumed that people, especially poor people, lack the competence to decide for themselves. Similarly, the failures of participation would seem strikingly banal if people, especfially those we are interested in, behaved the way we expected them to. But people do not behave as expected. Their interests may not be in the collective interest, and thier goals may not coincide with broader social goals.Economic Theory&Research,Health Economics&Finance,Environmental Economics&Policies,Labor Policies,Decentralization,Health Economics&Finance,Governance Indicators,Environmental Economics&Policies,ICT Policy and Strategies,Economic Theory&Research

As marismas da Baía de Paranaguá: características gerais, modos de apropriação e implicações para a legislação ambiental

This review presents the current knowledge on salt marshes of Paranaguá Bay (Southem Brazil) and analyses their floristic, faunistic and physiographic differences in relation to local mangroves. Usage and traditional management of local salt marshes have received scant attention in the literature and their potential resources and ecological functions are heavily underestimated. A re-enactment of environmental law is suggested, on the basis of a comparative analysis between structural and functional attributes of local mangroves and salt marshes

Determinants of the use of capital investment appraisal methods : evidence from the field

In this paper, it is argued that there are specific contingencies that explain why firms use and do not use specific capital investment appraisal methods; namely, the pressure of competitive environment, firm’s strategy, production technologies and firm’s age. Several studies on the impact of such variables on management systems can be found in the literature (Abernethy and Lillis, 1995; Langfield-Smith, 1997). Nevertheless, there is little empirical evidence on the factors that explain the use of capital investment appraisal methods (CIAM) by firms. A questionnaire was designed to collect empirical evidence on the use of capital investment appraisal methods in the larger 500 Portuguese non-financial companies. It is expected that, in practice, CIAM could be regarded not only as an ad hoc usage of more or less sophisticated techniques, but characterised by different levels of sophistication and completeness. In this paper, we present an appropriate questionnaire for the analysis of CIAM in practice. Moreover, some research hypotheses for further analysis are presented. Further work using different statistical approaches, different samples and case study research is expected

Development of working procedures of a 5 Axis CNC milling machine

Dissertação de mestrado em Mechanical EngineeringThe work developed and presented on this dissertation tends to the installation and configurations of a 5-axis CNC machine with the creation of working procedures intended to build a stable workflow that can be employed by any individual expected to use the machine. Being a large field within mechanical engineering as well as being involved in a large selection of different industrial sectors, the concept of 5-axis machining will be explored to develop knowledge in terms of CAM programming and manipulation/optimization of toolpaths. The importance/functioning of the transmission of information both from post-processor to the controller and from the controller to the actual machine is also a critical point in this work as they are directly related to the quality of the parts produced. To accomplish this, the theoretical knowledge foundations regarding CNC machining work were researched, studied, and explained. Furthermore, the machine model in question (HY-6040 5-axis CNC Router) was meticulously analysed regarding to the machines structure, post-processor, and controller. Upon assembling all this information, and through the production of some test parts, a permanent manufacture workflow for different machining approaches was established and described.O trabalho desenvolvido e apresentado nesta dissertação tende à instalação e configuração de uma máquina CNC de 5-eixos, com a criação de procedimentos de trabalho destinados a criar um fluxo de trabalho estável que possa ser empregue por qualquer individuo que pretenda utilizar a máquina. Sendo um grande campo dentro da engenharia mecânica e estando também envolvido numa grande seleção de diferentes setores industriais, o conceito de maquinagem em 5-eixos será explorado com a finalidade de desenvolver conhecimentos a nível de programação CAM e manipulação/otimização de trajetórias de corte. A importância/funcionamento da transmissão de informação quer do pôs-processador para o controlador, quer do controlador para a máquina constituem também um ponto critico neste trabalho já que estão diretamente relacionados com a qualidade das peças produzidas. Para a realização de tal, foram pesquisados, estudados e explicados os fundamentos do conhecimento teórico relativamente ao trabalho de maquinagem CNC. Para além disso, o modelo da máquina em questão (HY-6040 5-axis CNC Router) foi meticulosamente analisado quanto à estrutura da máquina, pós-processador e controlador. Após reunir toda esta informação, e través da produção de peças teste, foi estabelecido um fluxo de trabalho de manufatura (CAD/CAM/Maquinagem) para diferentes abordagens de maquinagem