Multiple-Locus Variable Number Tandem Repeat Analysis of Staphylococcus Aureus: Comparison with Pulsed-Field Gel Electrophoresis and spa-Typing

(MRSA) is required to study the routes and rates of transmission of this pathogen. Currently available typing techniques are either resource-intensive or have limited discriminatory ability. Multiple-locus variable number tandem repeat analysis (MLVA) may provide an alternative high throughput molecular typing tool with high epidemiological resolution.-sequence typing and PFGE, at the MLVA complex level with group separation values of 95.1% and 89.2%. MLVA could not discriminate between pig-related MRSA strains isolated from humans and pigs, corroborating the high degree of relationship. MLVA was also superior in the grouping of MRSA isolates previously assigned to temporal-spatial clusters with indistinguishable SpaTypes, demonstrating its enhanced epidemiological usefulness. that yields discrete and unambiguous data that can be used to assign biological meaningful genotypes and complexes and can be used for interlaboratory comparisons in network accessible databases. Results suggest that MLVA offsets the disadvantages of other high discriminatory typing approaches and represents a promising tool for hospital, national and international molecular epidemiology

Experience report: towards extending an OSEK-compliant RTOS with mixed criticality support

\u3cp\u3eBackground: With an increase of the number of features in a vehicle, the computational requirements also increase, and vehicles may contain up to 100 Electronic Control Units (ECUs) to accommodate these requirements. For cost-e ectiveness reasons, amongst others, it is considered desirable to limit the growth of, or preferably reduce, the number of ECUs. To that end, mixed criticality is a promising approach that received a lot of attention in the literature, primarily from a theoretical perspective. Aim: In this paper, we address mixed criticality from a practical perspective. Our prime goal is to extend an OSEK-compliant real-time operating system (RTOS) with mixed criticality support, enabling such support in the automotive domain. In addition, we aim at a system (i) supporting more than two criticality levels; (ii) with minimal overhead upon an increase of the so-called criticality level indicator of the system; (iii) requiring no changes to an underlying operating system; and (iv) featuring further extensions, such as hierarchical scheduling and multi-core. Method: We used the so-called adaptive mixed criticality (AMC) scheme as a starting point for mixed criticality. We extended that scheme from two to more than two criticality levels (satisfying (i)) and complemented it with specified behavior for criticality level changes. We baptized our extended scheme AMC*. Rather than selecting a specific OSEK-compliant RTOS, we selected ExSched, an operating system independent external CPU scheduler framework for real-time systems, which requires no modifications to the original operating system source code (satisfying (iii)) and features further extensions (satisfying (iv)). Results: Although we managed to build a functional prototype of our system, our experience with ExSched made us decide to rebuild the system with a specific OSEK-compliant RTOS, being µC/OS-II. We also briefly report upon our experience with AMC* and suggest directions for improvements. Conclusions: Compared to extending ExSched with AMC*, extending µC/OS-II turned out to be straightforward. Although we now have a basic system operational and available for experimentation, enhancements of the AMC*-scheme are considered desirable before exploitation in a vehicle.\u3c/p\u3

Experience report: towards extending an OSEK-compliant RTOS with mixed criticality support

Background: With an increase of the number of features in a vehicle, the computational requirements also increase, and vehicles may contain up to 100 Electronic Control Units (ECUs) to accommodate these requirements. For cost-e ectiveness reasons, amongst others, it is considered desirable to limit the growth of, or preferably reduce, the number of ECUs. To that end, mixed criticality is a promising approach that received a lot of attention in the literature, primarily from a theoretical perspective. Aim: In this paper, we address mixed criticality from a practical perspective. Our prime goal is to extend an OSEK-compliant real-time operating system (RTOS) with mixed criticality support, enabling such support in the automotive domain. In addition, we aim at a system (i) supporting more than two criticality levels; (ii) with minimal overhead upon an increase of the so-called criticality level indicator of the system; (iii) requiring no changes to an underlying operating system; and (iv) featuring further extensions, such as hierarchical scheduling and multi-core. Method: We used the so-called adaptive mixed criticality (AMC) scheme as a starting point for mixed criticality. We extended that scheme from two to more than two criticality levels (satisfying (i)) and complemented it with specified behavior for criticality level changes. We baptized our extended scheme AMC*. Rather than selecting a specific OSEK-compliant RTOS, we selected ExSched, an operating system independent external CPU scheduler framework for real-time systems, which requires no modifications to the original operating system source code (satisfying (iii)) and features further extensions (satisfying (iv)). Results: Although we managed to build a functional prototype of our system, our experience with ExSched made us decide to rebuild the system with a specific OSEK-compliant RTOS, being µC/OS-II. We also briefly report upon our experience with AMC* and suggest directions for improvements. Conclusions: Compared to extending ExSched with AMC*, extending µC/OS-II turned out to be straightforward. Although we now have a basic system operational and available for experimentation, enhancements of the AMC*-scheme are considered desirable before exploitation in a vehicle

An experience report on the integration of ECU software using an HSF-enabled real-time kernel

This paper gives an overview of the challenges we\u3cbr/\u3efaced when integrating automotive software components on an\u3cbr/\u3eembedded electronic control unit (ECU). The results include the\u3cbr/\u3edesign of a communication abstraction layer, management of\u3cbr/\u3escarce ECU resources and a demonstration of temporal isolation\u3cbr/\u3ebetween components in an industrial case study

Complete WGMs of LA-MRSA isolates obtained from a confirmed transmission event.

<p>The 4 isolates represent 3 household members and 1 isolate originated from a pig on the farm. All isolates were identical in PFGE, <i>spa</i>-typing and MLVA.</p

Detail of the WGMs of 16 LA-MRSA isolates originating from unrelated veterinarians showing the discriminatory power of whole genome mapping.

<p>The limited variation obtained by MLVA- and <i>spa</i>-typing is displayed on the right hand side of the WGMs. The blowup of the WGMs displays considerable variation in the SCC<i>mec</i> region.</p

Bacterial strains used in this study.

*<p>VET-study, isolates collected for a longitudinal MRSA carriage study among veterinarians and written consent was provided by all participants (E. Verkade personal communication).</p

Detail of whole genome maps showing differences between HA-MRSA outbreak isolates obtained from a large medical care center in the Netherlands.

<p>Based on molecular typing (<i>spa</i>-typing, MLVA and PFGE) all isolates were indistinguishable.</p

Detail of the whole genome maps of an outbreak of CA-MRSA (USA300) showing an additional DNA segment in 3 isolates.

<p>All isolates had <i>spa</i>-type t024 and MLVA-type MT308. The gel image on the right hand side shows the PFGE profiles with an additional 80 kb band in the lower 3 isolates.</p

Detail of the WGMs of two veterinarians and their household members showing transmission events.

<p>A and B denote the clusters with highly similar WGMs of isolates obtained from VET45 and his household members (light red block). C denotes the cluster with highly similar WGMs of isolates obtained from VET66 and his household members (blue block). Sampling time-points, sampling sites, <i>spa</i>-type, MLVA-type and PFGE-type are indicated on the right hand side of the maps. The PFGE-type numbers are arbitrary numbers.</p