The Abstraction Refinement Model and the Modification-Cost Problem

A problem common to systems and software engineering is that of estimating the cost of making changes to a system. For system modifications that include changes to the design history of the system this is the "modification-cost" problem. A solution to this problem is important to planning changes in large systems engineering projects. In this paper, a cost model based on the Abstraction Refinement Model (ARM) is proposed as a framework for deriving solutions to the modification-cost problem. The ARM is a characterization of software evolution that is also applicable to general systems. Modifications to systems and their design histories are described using the components of the ARM. The cost model is defined by functions on the ARM components. The derived solution is given by an abstract expression of the cost functions

Documentation Production Under Next Generation Technologies

This report describes the development of the Abstraction Refinement Model as a basis for linking the development and maintenance tasks in software systems. Documentation is critical in both efforts, and the reliance on development documentation during maintenance is characterized by the model and through a characterization of the development documentation requirement stipulated under DoD-STD2167A. The Abstraction Refinement Model enables a coherent characterization of the reverse engineering requirements generally caused by a faulty or inadequately documented development process. Within the context of the model, the Automated Documentation Design System (ADDS) is characterized, and the system is evaluated with regard to its current capabilities versus future potential. A set of recommendations regarding ADDS concludes the report

Requirements for a Software Maintenance Methodology

Software maintenance, although widely recognized as the most costly period in the life of a system, is given only passing consideration in life-cycle models. An extensive literature review shows the relationship between the development and maintenance phases to be ignored to a large extent. The Abstraction Refinement Model (ARM) describes the dependency of software maintenance on the quality of the documentation and depicts the adaptive and perfective maintenance forms as relying on earlier design and requirements documents to a greater degree than corrective and preventative maintenance. The ARM is effective in laying the foundations for a software maintenance methodology, particularly in explaining the role of reverse engineering. Coupling the ARM with the Objectives/Principles/Attributes procedure for the evaluation for software development methodologies proves effective in drawing the contrast with maintenance requirements. which are specifically identified for further study and assessment

Development of an AEGIS Maintenance Methodology Task 2: Models of the AEGIS Maintenance Process

Covering the Task 2 effort in the development of an AEGIS software maintenance methodology, the derivation of requirements from maintenance principles is summarized. Three models of the maintenance process provide the basis for identifying points of application. The mid-level (aggregate) model is the major focus of the methodology definition. Recommendations address the potential uses of different modeling perspectives, better balance between products and process assessment, use of metrics, and the selection of maintenance tools

Differential criterion of a bubble collapse in viscous liquids

The present work is devoted to a model of bubble collapse in a Newtonian viscous liquid caused by an initial bubble wall motion. The obtained bubble dynamics described by an analytic solution significantly depends on the liquid and bubble parameters. The theory gives two types of bubble behavior: collapse and viscous damping. This results in a general collapse condition proposed as the sufficient differential criterion. The suggested criterion is discussed and successfully applied to the analysis of the void and gas bubble collapses.Comment: 5 pages, 3 figure

Patterns of Natural and Human-Caused Mortality Factors of a Rare Forest Carnivore, the Fisher (Pekania pennanti) in California.

Wildlife populations of conservation concern are limited in distribution, population size and persistence by various factors, including mortality. The fisher (Pekania pennanti), a North American mid-sized carnivore whose range in the western Pacific United States has retracted considerably in the past century, was proposed for threatened status protection in late 2014 under the United States Endangered Species Act by the United States Fish and Wildlife Service in its West Coast Distinct Population Segment. We investigated mortality in 167 fishers from two genetically and geographically distinct sub-populations in California within this West Coast Distinct Population Segment using a combination of gross necropsy, histology, toxicology and molecular methods. Overall, predation (70%), natural disease (16%), toxicant poisoning (10%) and, less commonly, vehicular strike (2%) and other anthropogenic causes (2%) were causes of mortality observed. We documented both an increase in mortality to (57% increase) and exposure (6%) from pesticides in fishers in just the past three years, highlighting further that toxicants from marijuana cultivation still pose a threat. Additionally, exposure to multiple rodenticides significantly increased the likelihood of mortality from rodenticide poisoning. Poisoning was significantly more common in male than female fishers and was 7 times more likely than disease to kill males. Based on necropsy findings, suspected causes of mortality based on field evidence alone tended to underestimate the frequency of disease-related mortalities. This study is the first comprehensive investigation of mortality causes of fishers and provides essential information to assist in the conservation of this species

Structural basis for phosphorylation and lysine acetylation cross-talk in a kinase motif associated with myocardial ischemia and cardioprotection

Myocardial ischemia and cardioprotection by ischemic pre-conditioning induce signal networks aimed at survival or cell death if the ischemic period is prolonged. These pathways are mediated by protein post-translational modifications that are hypothesized to cross-talk with and regulate each other. Phosphopeptides and lysine-acetylated peptides were quantified in isolated rat hearts subjected to ischemia or ischemic pre-conditioning, with and without splitomicin inhibition of lysine deacetylation. We show lysine acetylation (acetyl-Lys)-dependent activation of AMP-activated protein kinase, AKT, and PKA kinases during ischemia. Phosphorylation and acetyl-Lys sites mapped onto tertiary structures were proximal in >50% of proteins investigated, yet they were mutually exclusive in 50 ischemic pre-conditioning- and/or ischemia-associated peptides containing the KXXS basophilic protein kinase consensus motif. Modifications in this motif were modeled in the C terminus of muscle-type creatine kinase. Acetyl-Lys increased proximal dephosphorylation by 10-fold. Structural analysis of modified muscle-type creatine kinase peptide variants by two-dimensional NMR revealed stabilization via a lysine-phosphate salt bridge, which was disrupted by acetyl-Lys resulting in backbone flexibility and increased phosphatase accessibility

Insulin and glucose play a role in foam cell formation and function

BACKGROUND: Foam cell formation in diabetic patients often occurs in the presence of high insulin and glucose levels. To test whether hyperinsulinemic hyperglycemic conditions affect foam cell differentiation, we examined gene expression, cytokine production, and Akt phosphorylation in human monocyte-derived macrophages incubated with two types of oxidized low density lipoprotein (LDL), minimally modified LDL (mmLDL) and extensively oxidized LDL (OxLDL). METHODS AND RESULTS: Using Affymetrix GeneChip(® )arrays, we found that several genes directly related to insulin signaling were changed. The insulin receptor and glucose-6-phosphate dehydrogenase were upregulated by mmLDL and OxLDL, whereas insulin-induced gene 1 was significantly down-regulated. In hyperinsulinemic hyperglycemic conditions, modified LDL upregulated Akt phosphorylation and expression of the insulin-regulated aminopeptidase. The level of proinflammatory cytokines, IL-lβ, IL-12, and IL-6, and of a 5-lipoxygenase eicosanoid, 5-hydroxyeicosatetraenoic acid (5-HETE), was also increased. CONCLUSION: These results suggest that the exposure of macrophages to modified low density lipoproteins in hyperglycemic hyperinsulinemic conditions affects insulin signaling and promotes the release of proinflammatory stimuli, such as cytokines and eicosanoids. These in turn may contribute to the development of insulin resistance

Addressing the Language Binding Problem With Dynamic Functional Connectivity During Meaningful Spoken Language Comprehension

During speech, how does the brain integrate information processed on different timescales and in separate brain areas so we can understand what is said? This is the language binding problem. Dynamic functional connectivity (brief periods of synchronization in the phase of EEG oscillations) may provide some answers. Here we investigate time and frequency characteristics of oscillatory power and phase synchrony (dynamic functional connectivity) during speech comprehension. Twenty adults listened to meaningful English sentences and non-sensical “Jabberwocky” sentences in which pseudo-words replaced all content words, while EEG was recorded. Results showed greater oscillatory power and global connectivity strength (mean phase lag index) in the gamma frequency range (30–80 Hz) for English compared to Jabberwocky. Increased power and connectivity relative to baseline was also seen in the theta frequency range (4–7 Hz), but was similar for English and Jabberwocky. High-frequency gamma oscillations may reflect a mechanism by which the brain transfers and integrates linguistic information so we can extract meaning and understand what is said. Slower frequency theta oscillations may support domain-general processing of the rhythmic features of speech. Our findings suggest that constructing a meaningful representation of speech involves dynamic interactions among distributed brain regions that communicate through frequency-specific functional networks