Compositional semantics for real-time distributed computing

We give a compositional denotational semantics for a real-time distributed language, based on the linear history semantics for CSP of Francez et al. Concurrent execution is not modelled by interleaving but by an extension of the maximal parallelism model of Salwicki, that allows the modelling of transmission time for communications. The importance of constructing a semantics (and in general a proof theory) for real-time is stressed by such different sources as the problem of formalizing the real-time aspects of Ada and the elimination of errors in real-time flight control software ([Sunday Times 7-22-84])

Analysis of Epigenetic Factors in Mouse Embryonic Neural Stem Cells Exposed to Hyperglycemia

BACKGROUND Maternal diabetes alters gene expression leading to neural tube defects (NTDs) in the developing brain. The mechanistic pathways that deregulate the gene expression remain unknown. It is hypothesized that exposure of neural stem cells (NSCs) to high glucose/hyperglycemia results in activation of epigenetic mechanisms which alter gene expression and cell fate during brain development. METHODS AND FINDINGS NSCs were isolated from normal pregnancy and streptozotocin induced-diabetic pregnancy and cultured in physiological glucose. In order to examine hyperglycemia induced epigenetic changes in NSCs, chromatin reorganization, global histone status at lysine 9 residue of histone H3 (acetylation and trimethylation) and global DNA methylation were examined and found to be altered by hyperglycemia. In NSCs, hyperglycemia increased the expression of Dcx (Doublecortin) and Pafah1b1 (Platelet activating factor acetyl hydrolase, isoform 1b, subunit 1) proteins concomitant with decreased expression of four microRNAs (mmu-miR-200a, mmu-miR-200b, mmu-miR-466a-3p and mmu-miR-466 d-3p) predicted to target these genes. Knockdown of specific microRNAs in NSCs resulted in increased expression of Dcx and Pafah1b1 proteins confirming target prediction and altered NSC fate by increasing the expression of neuronal and glial lineage markers. CONCLUSION/INTERPRETATION This study revealed that hyperglycemia alters the epigenetic mechanisms in NSCs, resulting in altered expression of some development control genes which may form the basis for the NTDs. Since epigenetic changes are reversible, they may be valuable therapeutic targets in order to improve fetal outcomes in diabetic pregnancy.This study is supported by the NUS bridging fund R-181-000-130-720. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Análisis de las Estrategias Metodológicas implementadas por el docente en el desarrollo del proceso de enseñanza- aprendizaje en la disciplina de Geografía e Historia de Nicaragua y su Didáctica en los alumnos/as de Primer año “B” del turno regular de Formación Inicial Docente en la Escuela Normal Central de Managua Alesio Blandón Juárez durante el I semestre del Curso Escolar 2016

El presente trabajo de investigación tiene como finalidad analizar la efectividad que tienen las Estrategias Metodológicas implementadas por el docente en el desarrollo del proceso de enseñanza- aprendizaje en la disciplina de Geografía de Nicaragua y su Didáctica en los alumnos/as de Primer año “B” del turno regular de Formación Inicial Docente en la Escuela Normal Central de Managua Alesio Blandón Juárez durante el I semestre del Curso Escolar 2016. Dicho trabajo de investigación tiene un enfoque naturista o cualitativo, es una vía de transformación social, a través de la cual el ser humano descubre la realidad que le rodea, determina los medios y procedimientos para actuar sobre ella y transformarla de acuerdo a una intensión social. Los procesos de investigación cualitativa, tienen como finalidad primordial la generación y construcción de conocimientos que contribuyen al desarrollo social y personal de cada uno de los miembros de una comunidad. La fase de recolección de los datos de la investigación desarrollada, se realizó de dos formas: una información que se recogió mediante la observación directa del comportamiento de los informantes claves y una información que se obtuvo mediante la interrogación de algunos informantes claves. Para ello, primeramente el investigador realizo una inmersión en el campo de trabajo, con el propósito de identificar los lugares adecuados para recoger y producir la información necesaria y requerid

Languages for Reactive Specifications: Synchrony Vs Asynchrony

Asynchronous and Synchronous languages have been in use for the specification of reactive systems. One of the main distinguishing features of these two classes lies in the way nondeterminism is used for the specification of programs. From this viewpoint, we analyze CSP (a typical asynchronous language) and Esterel (a synchronous language). The synchronous language Esterel is based on the notions of determinism, input nondeterminacy and parallelism whereas CSP is built on the notions of nondeterminism, concurrency and distribution. The main objectives of the study are to assess: 1. The role of nondeterminism in the specification of the behaviour and realization of programs: A clear distinction between local and global nondeterminism enables us to distinguish between the implementational nondeterminism and environmental or input nondeterminism. The results in this direction would enable one to achieve observable determinism where the implementational choices can be hidden and thus, anal..

Semantics and Verification of Hierarchical CRP Programs

Communicating Reactive Processes (CRP) paradigm unifies asynchronous and synchronous mechanisms of concurrent programming languages. As an example, CRP unifies Esterel and Hoare's Communicating Sequential Processes (CSP). It has been earlier shown that such a unification and in particular CRP can be used for the specification of hybrid systems and dynamic real-time systems. In this paper, we extend the CRP to support hierarchical refinement and describe a compositional semantics. Further, we show how verification can be done using the verification techniques and tools used for the verification of Esterel programs. We illustrate how a careful separation of Esterel and CSP mechanisms in CRP has enabled the use of the technique of verification by reductions for verification and illustrate the use of tools such as Auto/Autograph for the verification of CRP programs through the banker-teller example. 1 Introduction Programming languages that have been used for real-time programming can be ..

Programmed OL-systems

In this paper, two generalizations of OL-systems called strong programmed OL-systems and weak programmed OL-systems are introduced. The interesting feature is that the class of programmed OLs contains the class of CFPGs. The relationships with Chomskian grammars and other L-systems are established. The closure properties of the models introduced under various operations are studied

A linear time algorithm for obtaining the convex hull of a simple polygon

In this paper, a linear time algorithm is described for finding the convex hull of a simple (i.e. non-self intersecting) polygon