Extended support for limited preemption fixed priority scheduling for OSEK/AUTOSAR-compliant operating systems

Fixed Priority Scheduling (FPS) is the de facto standard in industry and it is the scheduling algorithm used in OSEK/AUTOSAR. Applications in such systems are compositions of so-called runnables, the functional entities of the system. Runnables are mapped to operating system tasks during system synthesis. In order to improve system performance it is proposed to execute runnables non-preemptively while varying the tasks threshold between runnables. This allows simpler resource access, which can reduce the stack usage of the system and improve the schedulability of the task sets. FPDS*, as a special case of fixed-priority scheduling with deferred preemptions, executes subjobs non-preemptively and preemption points have preemption thresholds, providing exactly the proposed behavior. However OSEK/AUTOSAR-conform systems cannot execute such schedules. In this paper we present an approach allowing the execution of FPDS* schedules. In our approach we exploit pseudo resources in order to implement FPDS*. It is further shown that our optimal algorithm produces a minimum number of resource accesses. In addition, a simulation-based evaluation is presented in which the number of resource accesses as well as the number of required pseudo-resources by the proposed algorithms are investigated. Finally, we report the overhead of resource access primitives using our measurements performed on an AUTOSAR-compliant operating system

Intra-component resource sharing on a virtual multiprocessor platform

Component-based software development facilitates the development process of large and complex software systems. By the advent of multiprocessors, the independently developed components can be integrated on a multi-core platform to achieve an efficient use of system hardware and a decrease in system power consumption and costs. In this paper, we consider a virtual multiprocessor platform where each component can be dynamically allocated to any set of processors of the platform with a maximum concurrency level. Global-EDF is used for intra-component scheduling. The existing analysis for such systems have assumed that tasks are independent. In this paper, we enable intra-component resource sharing for this platform. We investigate using a spin-based resource sharing protocol with the accompanying analysis that extends the existing analysis for independent tasks. We briefly illustrate and evaluate our initial results with an example

Multi-modal imaging for assessment of tissue-engineered bone in a critical-sized calvarial defect mouse model.

Tissue-engineered bone (TEB) analysis in vivo relies heavily on tissue histological and end-point evaluations requiring the sacrifice of animals at specific time points. Due to differences in animal response to implanted tissues, the conventional analytical methods to evaluate TEB can introduce data inconsistencies. Additionally, the conventional methods increase the number of animals required to provide an acceptable statistical power for hypothesis testing. Alternatively, our non-invasive optical imaging allows for the longitudinal analysis of regenerating tissue, where each animal acts as its own control, thus reducing overall animal numbers. In our 6 month feasibility study, TEB, consisting of a silk protein scaffold with or without differentiated mesenchymal stem cells, was implanted in a critical-sized calvarial defect mouse model. Osteogenesis of the TEB was monitored through signal variation, using magnetic resonance imaging (MRI) and near-infrared (NIR) optical imaging with IRDye® 800CW BoneTag(TM) (800CW BT, a bone-specific marker used to label osteogenically differentiated mesenchymal stem cells and mineralization). Histological endpoint measurements and computed tomography (CT) were used to confirm imaging findings. Anatomical MRI revealed decreased signal intensity, indicating mineralization, in the TEB compared to the control (i.e. silk scaffold only) at various growth stages. NIR optical imaging results demonstrated a signal intensity increase of the TEB compared to control. Interpretation of the imaging results were confirmed by histological analysis. Specifically, haematoxylin and eosin staining revealing de novo bone in TEB showed that 80% of the defect was covered by TEB, while only 40% was covered for the control. Taken together, these results demonstrate the potential of multi-modal non-invasive imaging to visualize and quantify TEB for the assessment of regenerative medicine strategies. Copyright © 2015 John Wiley & Sons, Ltd

Implications of protein corona on physico-chemical and biological properties of magnetic nanoparticles.

Interaction of serum proteins and nanoparticles leads to a nanoparticle-protein complex formation that defines the rational strategy for a clinically relevant formulation for drug delivery, hyperthermia, and magnetic resonance imaging (MRI) applications in cancer nanomedicine. Given this perspective, we have examined the pattern of human serum protein corona formation with our recently engineered magnetic nanoparticles (MNPs). The alteration in particle size, zeta potential, hemotoxicity, cellular uptake/cancer cells targeting potential, and MRI properties of the MNPs after formation of human serum (HS) protein corona were studied. Our results indicated no significant change in particle size of our MNPs upon incubation with 0.5-50 wt/v% human serum, while zeta potential of MNPs turned negative due to human serum adsorption. When incubated with an increased serum and particle concentration, apolipoprotein E was adsorbed on the surface of MNPs apart from serum albumin and transferrin. However, there was no significant primary or secondary structural alterations observed in serum proteins through Fourier transform infrared spectroscopy, X-ray diffraction, and circular dichroism. Hemolysis assay suggests almost no hemolysis at the tested concentrations (up to 1 mg/mL) for MNPs compared to the sodium dodecyl sulfate (positive control). Additionally, improved internalization and uptake of MNPs by C4-2B and Panc-1 cancer cells were observed upon incubation with human serum (HS). After serum protein adsorption to the surface of MNPs, the close vicinity within T1 (∼1.33-1.73 s) and T2 (∼12.35-13.43 ms) relaxation times suggest our MNPs retained inherent MRI potential even after biomolecular protein adsorption. All these superior clinical parameters potentially enable clinical translation and use of this formulation for next generation nanomedicine for drug delivery, cancer-targeting, imaging and theranostic applications