34 research outputs found

    Microprocessor implementation of a parallel processor

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    Information for organized work

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    In this position statement we claim that the organization of information in databases, knowledge bases, hypertexts and other integrated structures depends on the processes for which they are used. These processes can be highly structured, completely ad hoc or anything in between. Whether a standard procedure can effectively and efficiently be followed in the process, however, depends on the quality of the information available. The human actors in the process need a mechanism to relate the quality of the information and the quality of the standard procedure to the goals of the business activity. We argue that agent technology can be used to bridge the gap between highly structured situations with high quality data and ad hoc situations where little information is available or the information is not of the right quality

    The Effects of Health Insurance and a Usual Source of Care on a Child’s Receipt of Health Care

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    This paper focuses on active networks applications and in particular on the possible interactions among these applications. Active networking is a very promising research field which has been developed recently, and which poses several interesting challenges to network designers. A number of proposals for efficient active network architectures are already to be found in the literature. However, how two or more active network applications may interact has not being investigated so far. In this work, we consider a number of applications that have been designed to exploit the main features of active networks and we discuss what are the main benefits that these applications may derive from them. Then, we introduce some forms of interaction including interference and communications among applications, and identify the components of an active network architecture that are needed to support these forms of interaction. We conclude by presenting a brief example of an active network application exploiting the concept of interaction

    Team Automata for Spatial Access Control

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    Team automata provide a framework for capturing notions like coordination, collaboration, and cooperation in distributed systems. They consist of an abstract specification of components of a system and allow one to describe different interconnection mechanisms based upon the concept of "shared actions". This document considers access control mechanisms in the context of the team automata model. It demonstrates the model usage and utility for capturing information security and protection structures, and critical coordinations between these structures. On the basis of a spatial access metaphor, various known access control strategies are given a rigorous formal description in terms of synchronizations in team automata

    Specification of the primitive myeloid precursor pool requires signaling through Alk8 in zebrafish

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    In the zebrafish embryo, primitive hematopoiesis initiates in two spatially distinct regions. Rostrally, the cells of the anterior lateral plate mesoderm (ALPM) give rise exclusively to cells of the myeloid lineage in a pu.1-dependent manner [1-5]. Caudally, in the posterior lateral plate mesoderm (PLPM), the expression of gata1 defines a precursor pool that gives rise predominantly to the embryonic erythrocytes [6]. The transcription factor scl acts upstream of both gata1 and pu.1 in these precursor pools, activating a series of conserved transcription factors that cell-autonomously specify either myeloid or erythroid fates [1, 4, 7, 8]. However, the mechanisms underlying the spatial separation of the hematopoietic precursor pools and the induction of differential gene expression within these pools are not well understood. We show here that the Bmp receptor lost-a-fin/alk8 is required for rostral pu.1 expression and myelopoiesis, identifying an early genetic event that distinguishes between the induction of anterior and posterior hematopoiesis. Introducing a constitutively active version of the Alk8 receptor led to increased pu.1 expression, but the role of alk8 was independent of the scl-dependent cell-fate pathway. Furthermore, the role of Alk8 in myelopoiesis was genetically separable from its earlier role in dorsal-ventral embryonic patterning
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