Distributed object-oriented applications are commonly implemented atop middleware platforms such as CORBA, .NET Remoting, and Java remote method invocation (RMI). These platforms provide a simple ...mechanism to invoke methods of remote objects. Increasingly more applications are demanding nonfunctional properties such as fault tolerance, high availability, and adaptivity, which require extensions to distributed objects' basic interaction model. A fragmented-object model, such as the one Marc Shapiro proposed, can provide the required flexibility. It's far more generic and flexible than the traditional client-server approach. A fragmented object is a truly distributed object; it consists of multiple fragments located on multiple nodes. Such a model allows arbitrary partitioning of state and functionality on these fragments, and arbitrary internal interaction between fragments of a single object. We have investigated integrating a fragmented-object model into CORBA (AspectIX), which requires internal modifications to the CORBA object request broker. Our approach for transparently integrating fault-tolerant objects into .NET Remoting is also useful for seamlessly integrating fragmented objects. Our FORMI architecture integrates fragmented objects into Java RMI without requiring internal modifications to the RMI runtime
The aim of this study was the development of a reliable and fast method to estimate total abdominal fat volumes (TAF) in diabetic subjects on the basis of T1-weighted MR images. Thirty-seven patients ...with diabetes were examined (age 48 ± 13 y mean ± SD). A semiautomated computer assisted software program was developed to quantify intraabdominal (IAF), subcutaneous (SCF), and total abdominal fat volumes (TAF). The variability of image analysis for fat measurements between two observers and within observers was assessed. Mean volumes (± SD) for IAF, SCF and TAF were 10.5 1 (± 5.0 1), 15.1 1 (±7.3 1) and 25.7 1 (±11.5 1), respectively. Inter- and intraobserver reliability was excellent (r = 0.999 to r = 1.0). Per patient, the analysis required nine minutes in addition to a scan duration of seven minutes. As this analytic method using T1-weighted MR images allows a fast and reliable quantification of TAF, IAF and SCF, it may serve as a valuable tool for respective studies in diabetic subjects.
Development of a feasible and reliable method for determining abdominal fat using breath-hold T1-weighted magnetic resonance imaging.
The high image contrast of T1-weighted gradient echo MR sequences ...makes it possible to differentiate between abdominal fat and non-fat tissue. To obtain a high signal-to-noise ratio, the measurements are usually performed using phased array surface coils. Inhomogeneity of the coil sensitivity leads to inhomogeneity of the image intensities. Therefore, to examine the volume of abdominal fat, an automatic algorithm for intensity correction must be implemented. The analysis of the image histogram results in a threshold to separate fat from other tissue. Automatic segmentation using this threshold results directly in the fat volumes. The separation of intraabdominal and subcutaneous fat is performed by interactive selection in a last step.
The described correction of inhomogeneity allows for the segmentation of the images using a global threshold. The use of semiautomatic interactive volumetry makes the analysis more subjective. The variance of volumetry between observers was 4.6 %. The mean time for image analysis of a T1-weighted investigation lasted less than 6 minutes.
The described method facilitates reliable determination of abdominal fat within a reasonable period of time. Using breath-hold MR sequences, the time of examination is less than 5 minutes per patient.
Most middleware platforms lack sufficient support to provide reliable references for accessing distributed mobile objects in the context of dynamic environments, or they heavily depend on ...infrastructure mechanisms like a globally available location service. Based on the fragmented-object model and on our own middleware implementation AspectIX, this paper presents concepts and mechanisms that avoid outdated references for dynamically distributed objects without additional infrastructure services. Our approach is based on time-bound guarantees. Even in the context of malicious nodes and a partial invalidation of references a safe binding of the distributed object is guaranteed if ever possible.
Design and architectures for dependable embedded systems Henkel, Jörg; Bauer, Lars; Becker, Joachim ...
2011 Proceedings of the Ninth IEEE/ACM/IFIP International Conference on Hardware/Software Codesign and System Synthesis (CODES+ISSS),
10/2011
Conference Proceeding
The paper presents an overview of a major research project on dependable embedded systems that has started in Fall 2010 and is running for a projected duration of six years. Aim is a 'dependability ...co-design' that spans various levels of abstraction in the design process of embedded systems starting from gate level through operating system, applications software to system architecture. In addition, we present a new classification on faults, errors, and failures.
The purpose of this study was to develop a rapid and reliable method for the measurement of total abdominal fat volumes in diabetic patients using magnetic resonance imaging (MRI). Total volume ...coverage of the abdomen was obtained using T1-weighted images in 37 diabetic patients (age 48 +/- 13 y mean +/-SD). Quantification of intraabdominal (IAF), subcutaneous (SCF), and total abdominal fat volumes (TAF) was performed using a semiautomated computer assisted analysis. The variability of image analysis for fat measurements between two observers and within observers was assessed. Mean volumes (+/- SD) for IAF, SCF and TAF were 10.5 l (+/- 5.0 l), 15.1 l (+/-7.3 l) and 25.7 l (+/-11.5 l), respectively. Reliability of measurements was excellent for both observers (observer I: intraobserver reliability IAF, SCF and TAF: r = 0.999, r = 0.999 r = 1.0, observer II: r = 0.999, r = 0.999 and r = 1.0), as well as between both observers (interobserver reliability IAF, SCF, and TAF: r = 0.999, r = 0.999, r = 1.0). A single computer analysis required about 9 min in addition to 7 min scan time. The developed analysis method of MR images allows a rapid and reliable determination of total intraabdominal, subcutaneous and total fat volumes. This method has the potential to be very valuable in respective studies in patients with diabetes.
Many years of research on dependable, fault-tolerant software systems yielded many tool implementations for vulnerability analysis and experimental validation of resilience measures. We identify two ...disjoint classes of fault-injection (FI) experiment tools in the field, and argue that both are plagued by inherent deficiencies, such as insufficient target state access, little or no means to switch to another target system, and non-reusable experiment code. In this article, we present a novel design approach for a FI infrastructure that aims at combining the strengths of both classes. Our Fail* experiment framework provides carefully-chosen abstractions simplifying both the implementation of different simulator/hardware target backends and the reuse of experiment code, while retaining the ability for deep target-state access for specialized FI experiments. An exemplary report on first experiences with a prototype implementation based on existing x86 and ARM simulators demonstrates the tool's versatility.
Many years of research on dependable, fault-tolerant software systems yielded a myriad of tool implementations for vulnerability analysis and experimental validation of resilience measures. Trace ...recording and fault injection are among the core functionalities these tools provide for hardware debuggers or system simulators, partially including some means to automate larger experiment campaigns. We argue that current fault-injection tools are too highly specialized for specific hardware devices or simulators, and are developed in poorly modularized implementations impeding evolution and maintenance. In this article, we present a novel design approach for a fault-injection infrastructure that allows experimenting researchers to switch simulator or hardware back ends with little effort, fosters experiment code reuse, and retains a high level of maintainability.
In Schizosaccharomyces pombe the frequency of mating-type (MT) switching is reduced by mutations in the swi genes. The ten hitherto known swi genes can be subdivided into three classes: Ia, Ib and ...II. Strains having swi5 (class Ib), swi9 (class II) and swi10 (class II) mutations do not only show reduced MT switching, but also exhibit an increased sensitivity to UV- and gamma-rays. For that reason, 19 previously described rad genes were tested for their effect on MT switching. We found that swi9, "rad10", "rad16" and "rad20" are allelic with each other indicating that the former allocation of these rad mutations to three different genes must have been erroneous. Among the remaining 16 rad genes examined, rad22 seems to be a new class II swi gene. The double mutants swi5 swi9 and swi5 swi10, but not swi9 swi10, are much more sensitive to radiation than the respective single mutants. Thus a cumulative increase in sensitivity occurs only if the mutants belong to different classes; previously the same correlation was found with regard to cumulative effects in MT switching.
