Considering Human Aspects on Strategies for Designing and Managing Distributed Human Computation

A human computation system can be viewed as a distributed system in which the processors are humans, called workers. Such systems harness the cognitive power of a group of workers connected to the Internet to execute relatively simple tasks, whose solutions, once grouped, solve a problem that systems equipped with only machines could not solve satisfactorily. Examples of such systems are Amazon Mechanical Turk and the Zooniverse platform. A human computation application comprises a group of tasks, each of them can be performed by one worker. Tasks might have dependencies among each other. In this study, we propose a theoretical framework to analyze such type of application from a distributed systems point of view. Our framework is established on three dimensions that represent different perspectives in which human computation applications can be approached: quality-of-service requirements, design and management strategies, and human aspects. By using this framework, we review human computation in the perspective of programmers seeking to improve the design of human computation applications and managers seeking to increase the effectiveness of human computation infrastructures in running such applications. In doing so, besides integrating and organizing what has been done in this direction, we also put into perspective the fact that the human aspects of the workers in such systems introduce new challenges in terms of, for example, task assignment, dependency management, and fault prevention and tolerance. We discuss how they are related to distributed systems and other areas of knowledge.Comment: 3 figures, 1 tabl

Constructing fail-controlled nodes for distributed systems: a software approach

PhD ThesisDesigning and implementing distributed systems which continue to provide specified services in the presence of processing site and communication failures is a difficult task. To facilitate their development, distributed systems have been built assuming that their underlying hardware components are Jail-controlled, i.e. present a well defined failure mode. However, if conventional hardware cannot provide the assumed failure mode, there is a need to build processing sites or nodes, and communication infra-structure that present the fail-controlled behaviour assumed. Coupling a number of redundant processors within a replicated node is a well known way of constructing fail-controlled nodes. Computation is replicated and executed simultaneously at each processor, and by employing suitable validation techniques to the outputs generated by processors (e.g. majority voting, comparison), outputs from faulty processors can be prevented from appearing at the application level. One way of constructing replicated nodes is by introducing hardwired mechanisms to couple replicated processors with specialised validation hardware circuits. Processors are tightly synchronised at the clock cycle level, and have their outputs validated by a reliable validation hardware. Another approach is to use software mechanisms to perform synchronisation of processors and validation of the outputs. The main advantage of hardware based nodes is the minimum performance overhead incurred. However, the introduction of special circuits may increase the complexity of the design tremendously. Further, every new microprocessor architecture requires considerable redesign overhead. Software based nodes do not present these problems, on the other hand, they introduce much bigger performance overheads to the system. In this thesis we investigate alternative ways of constructing efficient fail-controlled, software based replicated nodes. In particular, we present much more efficient order protocols, which are necessary for the implementation of these nodes. Our protocols, unlike others published to date, do not require processors' physical clocks to be explicitly synchronised. The main contribution of this thesis is the precise definition of the semantics of a software based Jail-silent node, along with its efficient design, implementation and performance evaluation.The Brazilian National Research Council (CNPq/Brasil)

PeerCube: an Hypercube-based P2P Overlay Robust against Collusion and Churn

In this paper we present PeerCube, a DHT-based system that aims at minimizing performance penalties caused by high churn while preventing malicious peers from subverting the system through collusion. This is achieved by i) applying a clustering strategy to support quorum-based operations; ii) using a randomised insertion algorithm to reduce the probability with which colluding Byzantine peers corrupt clusters, and; iii) leveraging on the properties of PeerCube's hypercube structure to allow operations to be successfully handled despite the corruption of some clusters. Despite a powerful adversary that can inspect the whole system and issue malicious join requests as often as it wishes, PeerCube guarantees robust operations in O(logN) messages, with N the number of peers in the system. Extended simulations validate PeerCube robustness

UM ESTUDO DE CASO SOBRE IMPORTÂNCIA DO ENSINO MÉDIO INTEGRADO À EDUCAÇÃO PROFISSIONAL PARA AS TRAJETÓRIAS DE VIDA DE EGRESSOS DO INSTITUTO FEDERAL DO CEARÁ/CAMPUS FORTALEZA

O presente trabalho constitui um recorte de uma pesquisa de mestrado realizada junto a egressos dos cursos técnicos em Mecânica Industrial, Química e Telecomunicações, ofertados pelo do Instituto Federal do Ceará – IFCE/Campus Fortaleza na modalidade do Ensino Médio Integrado à Educação Profissional e Tecnológica – EMI, os quais concluíram seus respectivos cursos no período compreendido entre os anos de 2016 e 2018. Compreende, portanto, um estudo de caso, que contou com a utilização de métodos e técnicas de natureza qualitativa para a coleta e tratamento dos dados obtidos a partir da realização de entrevistas semiestruturadas. Partindo das reflexões de autores como Moura, (2007); Bremer e Kuenzer (2012); Ramos (2014) Frigotto, Ciavatta e Ramos (2005); dentre outros, esta pesquisa objetivou evidenciar os sentidos que os egressos atribuem à formação recebida, bem como a importância que ela assume para a melhoria de suas condições materiais de existência e para sua autorrealização. Os resultados encontrados revelaram que os egressos, em sua ampla maioria, percebem a formação recebida como muito importante para o delineamento de suas trajetórias profissionais e acadêmicas, constituindo-se um “divisor de águas” para a transformação de suas condições materiais de vida e para o seu desenvolvimento humano

Myofibroma of the oral cavity. A rare spindle cell neoplasm

Myofibroma is an uncommon spindle cell neoplasm rarely found in oral cavity. Typically, this lesion is seen in neonates and infants with few cases reported in adults patients. In the oral cavity, myofibroma occurs within the submucosal or intramuscular tissue and has a predilection by the tongue, buccal mucosa and lips. Microscopically, a typical biphasic pattern can be observed. Misdiagnosis included benign and malignant spindle cell lesions of nerve tissue or smooth muscle origin, such as neurofibroma, leiomyoma and sarcomas. Thus, immunohistochemical staining is a useful tool to identify the nature of neoplastic cells and to reach an accurate diagnosis. An immunohistochemical panel consisting of antibodies to vimentin, SMA, HHF-35, S-100p and desmin must be achieved. In most cases, positivity for vimentin, SMA and HHF-25 can be observed. Our report describes a solitary myofibroma of the tongue of a 23-year-old man with emphasis in clinical, histopathological and immunohistochemical features of this lesion