The Construction of Verification Models for Embedded Systems

The usefulness of verification hinges on the quality of the verification model. Verification is useful if it increases our confidence that an artefact bahaves as expected. As modelling inherently contains non-formal elements, the qualityof models cannot be captured by purely formal means. Still, we argue that modelling is not an act of irrationalism and unpredictable geniality, but follows rational arguments, that often remain implicit. In this paper we try to identify the tacit rationalism in the model construction as performed by most people doing modelling for verification. By explicating the different phases, arguments, and design decisions in the model construction, we try to develop guidelines that help to improve the process of model construction and the quality of models

Min-Max Theorems for Packing and Covering Odd (u,v)(u,v)-trails

We investigate the problem of packing and covering odd $(u,v)$-trails in a graph. A $(u,v)$-trail is a $(u,v)$-walk that is allowed to have repeated vertices but no repeated edges. We call a trail odd if the number of edges in the trail is odd. Let $\nu(u,v)$ denote the maximum number of edge-disjoint odd $(u,v)$-trails, and $\tau(u,v)$ denote the minimum size of an edge-set that intersects every odd $(u,v)$-trail. We prove that $\tau(u,v)\leq 2\nu(u,v)+1$. Our result is tight---there are examples showing that $\tau(u,v)=2\nu(u,v)+1$---and substantially improves upon the bound of $8$ obtained in [Churchley et al 2016] for $\tau(u,v)/\nu(u,v)$. Our proof also yields a polynomial-time algorithm for finding a cover and a collection of trails satisfying the above bounds. Our proof is simple and has two main ingredients. We show that (loosely speaking) the problem can be reduced to the problem of packing and covering odd $(uv,uv)$-trails losing a factor of 2 (either in the number of trails found, or the size of the cover). Complementing this, we show that the odd-$(uv,uv)$-trail packing and covering problems can be tackled by exploiting a powerful min-max result of [Chudnovsky et al 2006] for packing vertex-disjoint nonzero $A$-paths in group-labeled graphs

The Mistastin Lake Impact Structure As A Terrestrial Analogue Site For Lunar Science And Exploration

The impact cratering record on the Moon is important for many reasons, from understanding early solar system chronology to probing the lunar interior. In order to maximize scientific return from future lunar missions, it is useful to: 1) study terrestrial impact craters to better understand impact processes and products, and 2) develop appropriate human and robotic exploration strategies aligned with geological goals. This research shows that the intermediate-size Mistastin Lake impact structure, in northern Labrador, Canada, is an unparalleled lunar analogue site, which includes both an anorthositic target and an almost complete suite of impact lithologies, including proximal ejecta deposits. New remote sensing, field mapping, and microscopy data are used to develop new structural and geological models of the Mistastin Lake impact structure. The results of this study show that a multi-stage ejecta emplacement model is required to explain the observations. It is also shown that impact melt-bearing breccias or “suevites” at Mistastin were emplaced as flows, were never airborne, and were formed from the mixing of impact melt flows with underlying lithic materials. In order to maximize scientific return from future lunar missions, this work also focused on developing appropriate human and robotic exploration strategies aligned with geological goals. We show that precursor reconnaissance missions provide surface geology visualization at resolutions and from viewpoints not achievable from orbit. Within such a mission concept, geological tasks are best divided between fixed-executional approaches, in which tasks are fairly repetitive and are carried out by an unskilled surface agent, and an adaptive-exploratory approach, where a skilled agent makes observations and interpretations and the field plan can adapt to these findings as the agent progresses. Operational considerations that help increase scientific return include: extensive pre-mission planning using remote sensing data; defining flexible plans and science priorities to respond to changing conditions; including mutually cross-trained scientists and engineers on the field team; and adapting traverses to accommodate field crew input and autonomy. A phased approach for human exploration proved successful in incorporating astronaut feedback and allowed more autonomy for astronauts to determine optimal sampling localities and sites for detailed observations

Religious leaders\u27 perceptions of advance care planning: a secondary analysis of interviews with Buddhist, Christian, Hindu, Islamic, Jewish, Sikh and Bahai leaders

Background: International guidance for advance care planning (ACP) supports the integration of spiritual and religious aspects of care within the planning process. Religious leaders’ perspectives could improve how ACP programs respect patients’ faith backgrounds. This study aimed to examine: (i) how religious leaders understand and consider ACP and its implications, including (ii) how religion affects followers’ approaches to end-of-life care and ACP, and (iii) their implications for healthcare. Methods: Interview transcripts from a primary qualitative study conducted with religious leaders to inform an ACP website, ACPTalk, were used as data in this study. ACPTalk aims to assist health professionals conduct sensitive conversations with people from different religious backgrounds. A qualitative secondary analysis conducted on the interview transcripts focussed on religious leaders’ statements related to this study’s aims. Interview transcripts were thematically analysed using an inductive, comparative, and cyclical procedure informed by grounded theory. Results: Thirty-five religious leaders (26 male; mean 58.6-years-old), from eight Christian and six non-Christian (Jewish, Buddhist, Islamic, Hindu, Sikh, Bahá’í) backgrounds were included. Three themes emerged which focussed on: religious leaders’ ACP understanding and experiences; explanations for religious followers’ approaches towards end-of-life care; and health professionals’ need to enquire about how religion matters. Most leaders had some understanding of ACP and, once fully comprehended, most held ACP in positive regard. Religious followers’ preferences for end-of-life care reflected family and geographical origins, cultural traditions, personal attitudes, and religiosity and faith interpretations. Implications for healthcare included the importance of avoiding generalisations and openness to individualised and/ or standardised religious expressions of one’s religion. Conclusions: Knowledge of religious beliefs and values around death and dying could be useful in preparing health professionals for ACP with patients from different religions but equally important is avoidance of assumptions. Community-based initiatives, programs and faith settin

[Book Review] The End of Financialization? Review Essay

Books reviewed: Greta Krippner, 2011: Capitalizing on Crisis. Cambridge, MA: Harvard University Press; Amato, Massimo and Lucca Fantacci, 2012: The End of Finance. London: Polity Pres

Enhancement of perfluorooctanoate and perfluorooctanesulfonate activity at acoustic cavitation bubble interfaces

Acoustic cavitation driven by ultrasonic irradiation decomposes and mineralizes the recalcitrant perfluorinated surfactants perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA). Pyrolytic cleavage of the ionic headgroup is the rate-determining step. In this study, we examine the sonochemical adsorption of PFOX, where X = S for PFOS and A for PFOA, by determining kinetic order and absolute rates over an initial PFOX concentration range of 20 nM to 200 μM. Sonochemical PFOX kinetics transition from pseudo-first-order at low initial concentrations, [PFOX]_i 40 μM, as the bubble interface sites are saturated. At PFOX concentrations below 100 μM, concentration-dependent rates were modeled with Langmuir−Hinshelwood (LH) kinetics. Empirically determined rate maximums, V_(Max)^(−PFOA) = 2230 ± 560 nM min^−1 and V_(Max)^(−PFOS) = 230 ± 60 nM min^−1, were used in the LH model, and sonochemical surface activities were estimated to be K_(Sono)^(PFOS) = 120000 M^−1 and K_(Sono)^(PFOA) = 28500 M^−1, 60 and 80 times greater than equilibrium surface activities, K_(Eq)^(PFOS) and K_(Eq)^(PFOA). These results suggest enhanced sonochemical degradation rates for PFOX when the bubble interface is undersaturated. The present results are compared to previously reported sonochemical kinetics of nonvolatile surfactants

A direct optical method for the study of grain boundary melting

The structure and evolution of grain boundaries underlies the nature of polycrystalline materials. Here we describe an experimental apparatus and light reflection technique for measuring disorder at grain boundaries in optically clear material, in thermodynamic equilibrium. The approach is demonstrated on ice bicrystals. Crystallographic orientation is measured for each ice sample. The type and concentration of impurity in the liquid can be controlled and the temperature can be continuously recorded and controlled over a range near the melting point. The general methodology is appropriate for a wide variety of materials.Comment: 8 pages, 8 figures, updated with minor changes made to published versio

Forschungsdaten-Dienste für die Max-Planck-Gesellschaft

Das Poster bietet einen Überblick über die Forschungsdaten-Dienste der Max Plank Digital Library (MPDL) als Serviceeinrichtung für die Max-Planck-Gesellschaft (MPG). Das Ziel ist eine effiziente Unterstützung der MPG-Wissenschaftler beim Management ihrer Forschungsdaten durch Beratung, Vernetzung und die Bereitstellung von Infrastruktur in Form von Serviceangeboten entlang der FAIR-Prinzipien

Hydrodynamic lift of vesicles under shear flow in microgravity

The dynamics of a vesicle suspension in a shear flow between parallel plates has been investigated under microgravity conditions, where vesicles are only submitted to hydrodynamic effects such as lift forces due to the presence of walls and drag forces. The temporal evolution of the spatial distribution of the vesicles has been recorded thanks to digital holographic microscopy, during parabolic flights and under normal gravity conditions. The collected data demonstrates that vesicles are pushed away from the walls with a lift velocity proportional to $\dot{\gamma} R^3/z^2$ where $\dot{\gamma}$ is the shear rate, $R$ the vesicle radius and $z$ its distance from the wall. This scaling as well as the dependence of the lift velocity upon vesicle aspect ratio are consistent with theoretical predictions by Olla [J. Phys. II France {\bf 7}, 1533--1540 (1997)].Comment: 6 pages, 8 figure

Leached antireflection surfaces Part 3. Chemical release data for leached BK-7 borosilicate glass

Chemical release data for glass constituents and adsorption data for solution constituents onto the glass surface are presented for aqueous leaching of BK-7 glass. Marked differences in release rates were observed between film-forming and non-film-forming solutions due to adsorption of solution-derived Al3+ ions onto the glass surface