A Model-Derivation Framework for Software Analysis

Model-based verification allows to express behavioral correctness conditions like the validity of execution states, boundaries of variables or timing at a high level of abstraction and affirm that they are satisfied by a software system. However, this requires expressive models which are difficult and cumbersome to create and maintain by hand. This paper presents a framework that automatically derives behavioral models from real-sized Java programs. Our framework builds on the EMF/ECore technology and provides a tool that creates an initial model from Java bytecode, as well as a series of transformations that simplify the model and eventually output a timed-automata model that can be processed by a model checker such as UPPAAL. The framework has the following properties: (1) consistency of models with software, (2) extensibility of the model derivation process, (3) scalability and (4) expressiveness of models. We report several case studies to validate how our framework satisfies these properties.Comment: In Proceedings MARS 2017, arXiv:1703.0581

Non-Markovian entanglement dynamics in the presence of system-bath coherence

A complete treatment of the entanglement of two-level systems, which evolves through the contact with a thermal bath, must include the fact that the system and the bath are not fully separable. Therefore, quantum coherent superpositions of system and bath states, which are almost never fully included in theoretical models, are invariably present when an entangled state is prepared experimentally. We show their importance for the time evolution of the entanglement of two qubits coupled to independent baths. In addition, our treatment is able to handle slow and low-temperature thermal baths.Comment: Accepted for publication in Phys. Rev. Lett

A Model-Derivation Framework for Software Analysis

Model-based verification allows to express behavioral correctness conditions like the validity of execution states, boundaries of variables or timing at a high level of abstraction and affirm that they are satisfied by a software system. However, this requires expressive models which are difficult and cumbersome to create and maintain by hand. This paper presents a framework that automatically derives behavioral models from real-sized Java programs. Our framework builds on the EMF/ECore technology and provides a tool that creates an initial model from Java bytecode, as well as a series of transformations that simplify the model and eventually output a timed-automata model that can be processed by a model checker such as UPPAAL. The framework has the following properties: (1) consistency of models with software, (2) extensibility of the model derivation process, (3) scalability and (4) expressiveness of models. We report several case studies to validate how our framework satisfies these properties.Comment: In Proceedings MARS 2017, arXiv:1703.0581

BMP-2 and BMP-4 signalling in the developing spinal cord of human and rat embryos

Bone morphogenetic proteins (BMPs) are multifunctional growth factors implicated in multiple biological events. Studies on mice, chickens and other experimental animals have shown that BMP signalling plays critical role in embryonic development, in particular in the neural patterning. In our study we comparatively evaluated BMP-2 and BMP-4 protein expression in the developing spinal cord of human and rat embryos. The human and rat embryos of Carnegie stages 14, 18 and 20 were embedded in paraffin and cut serially in transversal direction. BMP-2 and BMP-4 were detected by immunohistochemical staining. Spatial and temporal expression pattern of BMP-s during early stages of spinal cord development was similar in human and rat embryos. Higher expression of BMP-s was seen in the dorsal and lower expression in the ventral part of the developing spinal cord both in human and rat embryos. However, temporal difference in the expression of BMPs in the non-neural ectoderm between human and rat embryos was noted. Staining of BMP-s in the non-neural ectoderm adjacent to the developing spinal cord in the human embryos seemed to have a tendency to decrease from earlier to later developmental stages, while in rat embryos there was an opposite tendenc

Resection of peritoneal metastases causing malignant small bowel obstruction

Background: Resection of peritoneal metastases has been shown to improve survival in patients with abdominal metastatic disease from abdominal or extra abdominal malignancy. This study evaluates the benefit of peritoneal metastatic resection in patients with malignant small bowel obstruction and a past history of treated cancer. Patients and methods: Patients undergoing laparotomy for resection of peritoneal metastases from recurrence of previous cancer between 1992-2003 were reviewed retrospectively. Data were collected about type of primary cancer, interval to recurrence, extent of the disease and completeness of resection, morbidity and mortality and long-term survival. Results: Between 1992 and 2003 there were 79 patients (median age 62, range 19-91) who had laparotomy for small bowel obstruction due to recurrent cancer. The primary cancer was colorectal (31), gynaecologic cancer (19), melanoma (16) and others (13). Overall, the rate of complications was 35% and mortality was 10%. Median survival was 5 months; patients with history of colorectal cancer had better survival than other cancer (median survival 7 months vs. 4 months; p = 0.02). Multivariate analysis showed that the extent of recurrent disease was the only factor that affected overall survival. Conclusion: Laparotomy for small bowel obstruction is a worthwhile option for patients with malignant small bowel obstruction. Although it is associated with significant morbidity and mortality it offers a reasonable survival benefit in particular for patients with completely resectable disease

Expression of Pax2 protein during the formation of the central nervous system in human embryos

Members of the paired box (Pax) gene family are expressed in distinctive regions of the developing central nervous system, supporting a role of neural patterning. In this study, Pax2 protein expression was examined in the developing neural tube by immunohistochemistry methods in 30 human embryos of Carnegiestages (CS) 10–20 collected after legal abortions. Pax2 expression was detected along the boundaries of main divisions of the developing brain and spinal cord. However, Pax2 expression was found to be stronger in the developing brain than in the spinal cord of the same young embryos in CS 10–14, which was the mostremarkable at CS 10. Pax2 expression was detected in the developing forebrain,midbrain and hindbrain. At later stages (CS 16–20) Pax2 expression was observed in the midbrain-hindbrain boundary and also in the developing diencephalon and cerebellum. In the wall of developing spinal cord Pax2 expression was detected in the ventricular, mantel and marginal layers. Pax2 staining was seen to increase throughout the later stages of spinal cord development and significantly stronger expression was found at CS 16–20 compared to CS 10. Furthermore, spatially restricted expression of Pax2 was observed along the compartmental dorsal-ventralaxis of the spinal cord as Pax2 staining was weaker in the ventricular layer of the ventral part of the developing spinal cord compared with developing area of dorsal part

Ion-implantation-caused special damage profiles determined by spectroscopic ellipsometry in crystalline and in relaxed (annealed) amorphous silicon

We previously developed a fitting method of several parameters to evaluate ion-implantation-caused damage profiles from spectroscopic ellipsometry (SE) (M. Fried et al., J. Appl. Phys., 71 (1992) 2835). Our optical model consists of a stack of layers with fixed and equal thicknesses and damage levels described by a depth profile function (coupled half Gaussians). The complex refractive index of each layer is calculated from the actual damage level by Bruggeman effective medium approximation (EMA) using crystalline (c-Si) and amorphous (a-Si) silicon as end-points. Two examples are presented of the use of this method with modified optical models. First, we investigated the surface damage formed by room temperature B+ and N+ implantation into silicon. For the analysis of the SE data we added a near surface amorphous layer to the model with variable thickness. Second, we determined 20 keV B+ implantation-caused damage profiles in relaxed (annealed) amorphous silicon. In this special case, the complex refractive index of each layer was calculated from the actual damage level by the EMA using relaxed a-Si and implanted a-Si as end-points. The calculated profiles are compared with Monte Carlo simulations (TRIM code); good agreement is obtained

How wearing headgear affects measured head-related transfer functions

International audienceThe spatial representation of sound sources is an essential element of virtual acoustic environments (VAEs). When determining the sound incidence direction, the human auditory system evaluates monaural and binaural cues, which are caused by the shape of the pinna and the head. While spectral information is the most important cue for elevation of a sound source, we use differences between the signals reaching the left and the right ear for lateral localization. These binaural differences manifest in interaural time differences (ITDs) and interaural level differences (ILDs). In many headphone-based VAEs, head-related transfer functions (HRTFs) are used to describe the sound incidence from a source to the left and right ear, thus integrating both monaural and the binaural cues. Specific aspects, like for example the individual shape of the head and the outer ears (e.g. Bomhardt, 2017), of the torso (Brinkmann et al., 2015), and probably even of headgear (Wersenyi, 2005; Wersenyi, 2017) influence the HRTFs and thus probably as well localization and other perceptual attributes.<par>Generally speaking, spatial cues are modified by headgear, for example by wearing a baseball cap, a bicycle helmet, or a head-mounted display, which nowadays is often used in VR applications. In many real life situations, however, a good localization performance is important when wearing such items, e.g. in order to determine approaching vehicles when cycling. Furthermore, when performing psychoacoustic experiments in mixed-reality applications using head-mounted displays, the influence of the head-mounted display on the HRTFs must be considered. Effects of an HTC Vive head-mounted display on localization performance have already been shown in Ahrens et al. (2018). To analyze the influence of headgear for varying directions of incidence, measurements of HRTFs on a dense spherical sampling grid are required. However, HRTF measurements of a dummy head with various headgear are still rare, and to our knowledge only one dataset measured for an HTC Vice on a sparse grid with 64 positions is freely accessible (Ahrens, 2018).<par>This work presents high-density measurement data of HRTFs from a Neumann KU100 and a HEAD acoustics HMS II.3 dummy head, either equipped with a bicycle helmet, a baseball cap, an Oculus Rift head-mounted display, or a set of extra-aural AKG K1000 headphones. For the measurements, we used the VariSphear measurement system (Bernschütz, 2010), allowing precise positioning of the dummy head at the spatial sampling positions. The various HRTF sets were captured on a full spherical Lebedev grid with 2702 points.<par>In our study, we analyze the measured datasets in terms of their spectrum, their binaural cues, and regarding their localization performance based on localization models, and compare the results to reference measurements of the dummy heads without headgear. The results show that differences to the reference without headgear vary significantly depending on the type of the headgear. Regarding the ITDs and ILDs, the analysis reveals the highest influences for the AKG K1000. While for the Oculus Rift head-mounted display, the ITDs and ILDs are mainly affected for frontal directions, only a very weak influence of the bicycle helmet and the baseball cap on ITDs and ILDs was observed. For the spectral differences to the reference the results show maximal deviations for the AKG K1000, the lowest for the Oculus Rift and the baseball cap. Furthermore, we analyzed for which incidence directions the spectrum is influenced most by the headgears. For the Oculus Rift and the baseball cap, the strongest deviations were found for contralateral sound incidence. For the bicycle helmet, the directions mostly affected are as well contralateral, but shifted upwards in elevation. Finally, the AKG K1000 headphones generally has the highest influence on the measured HRTFs, which becomes maximal for sound incidence from behind.<par>The results of this study are relevant for applications where headgears are worn and localization or other aspects of spatial hearing are considered. This could be the case, for example in mixed-reality applications where natural sound sources are presented while the listener is wearing a head-mounted display, or when investigating localization performance in certain situations, e.g. in sports activities where headgears are used. However, it is an important intention of this study to provide a freely available database of HRTF sets which is well suited for auralization purposes and which allows to further investigate the influence of headgear on auditory perception. The HRTF sets will be publicly available in the SOFA format under a Creative Commons CC BY-SA 4.0 license

Data Analysis Techniques for Fan Performance in Highly-Distorted Flows from Boundary Layer Ingesting Inlets

The design of a unique distortion-tolerant fan for a high-bypass ratio boundary-layer ingesting propulsion system has been completed and a rig constructed and tested in the NASA Glenn 8x6 wind tunnel. Processing the data from the experiment presented some interesting challenges because of the complexity of the experimental setup and the flow through the test rig. The experiment was run in three phases, each of which employed a unique complement of inlet throat and fan face instrumentation to avoid the blockage that would have resulted from simultaneously installing all of the rakes. The measurement from the individual test points were subsequently combined to compute the overall stage performance. A CFD model of the experiment was used to gain understanding of the flow field and to test some of the techniques proposed for interpolating and extrapolating the measurements into regions where measurements were not made. This capability became extremely useful when it was discovered that there was an unexpected total temperature distortion in the tunnel. The CFD model was modified by inserting a total temperature profile at the upstream boundary that mimicked the measured distortion where measurements were available and that CFD solution was used to investigate methods to infer the complete total temperature field at the fan face

A timed-automata approach for critical path detection in a soft real-time application

In this paper, we report preliminary ideas from our project called “Time Performance Improvement With Parallel Processing Systems” (TIPS). In the TIPS project, we plan to take advantage of multi-core platforms for performance improvement by parallelizing a complex soft real-time application. In order to increase the timing performance, one needs to adapt the optimizations on the critical execution paths of an application which are both significantly time consuming and important from user requirements' perspective. In this work, we present an approach how to detect critical paths in a target application