A framework for requirements engineering for context-aware services

Context-aware services, especially when made available to mobile devices, constitute an interesting but very challenging domain. It poses fundamental problems for both requirements engineering, software architecture, and their relationship. We propose a novel, reflection-based framework for requirements engineering for this class of applications. The framework addresses the key difficulties in this field, such as changing context and changing requirements. We report preliminary work on this framework and suggest future directions

Specific ion channels contribute to key elements of pathology during secondary degeneration following neurotrauma

Background: Following partial injury to the central nervous system, cells beyond the initial injury site undergo secondary degeneration, exacerbating loss of neurons, compact myelin and function. Changes in Ca 2+ flux are associated with metabolic and structural changes, but it is not yet clear how flux through specific ion channels contributes to the various pathologies. Here, partial optic nerve transection in adult female rats was used to model secondary degeneration. Treatment with combinations of three ion channel inhibitors was used as a tool to investigate which elements of oxidative and structural damage related to long term functional outcomes. The inhibitors employed were the voltage gated Ca 2+ channel inhibitor Lomerizine (Lom), the Ca 2+ permeable AMPA receptor inhibitor YM872 and the P2X 7 receptor inhibitor oxATP. Results: Following partial optic nerve transection, hyper-phosphorylation of Tau and acetylated tubulin immunoreactivity were increased, and Nogo-A immunoreactivity was decreased, indicating that axonal changes occurred acutely. All combinations of ion channel inhibitors reduced hyper-phosphorylation of Tau and increased Nogo-A immunoreactivity at day 3 after injury. However, only Lom/oxATP or all three inhibitors in combination significantly reduced acetylated tubulin immunoreactivity. Most combinations of ion channel inhibitors were effective in restoring the lengths of the paranode and the paranodal gap, indicative of the length of the node of Ranvier, following injury. However, only all three inhibitors in combination restored to normal Ankyrin G length at the node of Ranvier. Similarly, HNE immunoreactivity and loss of oligodendrocyte precursor cells were only limited by treatment with all three ion channel inhibitors in combination. Conclusions: Data indicate that inhibiting any of a range of ion channels preserves certain elements of axon and node structure and limits some oxidative damage following injury, whereas ionic flux through all three channels must be inhibited to prevent lipid peroxidation and preserve Ankyrin G distribution and OPCs

Architectural Reflection: Bridging the Gap Between a Running System and its Architectural Specification

As the size and complexity of software systems increase, a relevant part of the system overall functionality shifts from the applicative domain to run-time system management activities, i.e., management activities which cannot be performed off-line. These range from monitoring to dynamic reconfiguration and, for non-stopping systems, also include evolution, i.e., addition or replacement of components or entire subsystems. In current practice, run-time system management is impeded by the fact that the knowledge of the overall structure and functioning of the system (i.e., its software architecture) is confined in design specification documents, while it is only implicit in running systems. In this paper we introduce, provide rationale for, and briefly demonstrate an approach to system management where the system maintains, and operates on, an architectural description of itself. This description is causally connected to the system's concrete structure and state, i.e., any change of the ..

A Fresh Look at Programming-in-the-Large

Realizing a shift of software engineering towards a component-based approach to software development requires the development of higher level programming systems supporting the development of systems from components. This paper presents a novel approach to the design of large software systems where a program-in-the-large describing the system's architecture is executed at run-time to rule over the assembly and dynamic cooperation of components. This approach has several advantages following from a clean separation of concerns between programming-in-the-small and programming-in-the-large issues in instantiated systems

Pre-clinical assessment of the long-term endurance of cemented hip stems. Part 1: effect of daily activities (a comparison of two load histories)

The loads during daily activities contribute to fixation failure of cemented hip stems. In-vitro preclinical testing so far has consisted of simulating one or two conditions. Only a small percentage of hip implants fail, with a higher failure rate in most active patients. The goal was to define a procedure to assess the long-term effect of the lifestyle of a reasonably active patient on implant micromotions. Thus, a cyclic load of constant amplitude is unsuitable. All activities inducing high loads were included, to replicate the most critical scenario in terms of fatigue. The following motor tasks were simulated: stair climbing and descending, car entry and exit, bathtub entry and exit, and stumbling. An in-vitro simulation running for 15 days was able to replicate the load peaks occurring in 24 years of patient activity. Inducible micromotion and permanent migration were monitored. The load history was successfully applied to two different designs with known clinical performance, yielding significantly different micromotions for the two types. Results from the present load history were compared against a simpler profile including only stair climbing. Results showed that the new load profile is more sensitive to differences and can more easily discriminate between different designs. Part 2 of this work describes a further validation against retrieved implants

Myelin internode length following partial ON transection.

<p>Representative images of a single slice from the z stacks show ventral axons of control animals (A) and at 3 months following injury (B) anterogradely traced with CTB (green); paranodes are immunohistochemically labelled with Caspr and nodes with Nav1.6. C: The length of myelin internodes (indicated by <) under 110 µm were measured between paranodes (Caspr+ structures, red, confirmed by the presence of Nav1.6+ sodium channels, blue, at the node, indicated by brackets) and the data range, 25% and 75% percentile, median and mean (indicated by *) were displayed in the box plot. D: Mean number of internodes visible per FOV ± S.E (*p<0.05). Scale bar: 20 µm.</p

Proliferation of oligodendroglia subpopulations following partial ON transection.

<p>Oligodendroglia and other olig2+ glia were identified with antibodies to NG2 (A), olig2 (B) and Ki67 (C), or with CC1 (E), olig2 (F) and Ki67 (G). D: Cells indicated are Ki67+/NG2+/olig2+ (>) and Ki67−/NG2+/olig2+ (>>). H: Cells indicated are Ki67+/CC1+/olig2+ (>) and Ki67−/CC1+/olig2+ (>>). Proliferating Ki67+/IBA1+ cells (I, indicated by >) and to a lesser extent Ki67+/GFAP+ cells (J) were observed after injury; representative examples at 3 days shown. K–P: Quantification of the mean density ± S.E of oligodendroglia and other olig2+ glia populations following partial transection. Densities of Ki67– cells are represented by black bars while densities of Ki67+ cells are represented by red bars and differences from control indicated by Δ(p≤0.05). Overall differences in total density (combined Ki67+ and Ki67– values) compared to control are indicated by *(p≤0.05). Q: Summary graph of Ki67+ mean densities of all oligodendroglia and other olig2+ glia subpopulations. Scale bar A–H: 20 µm, I–J: 10 µm.</p