Approaching the Coverability Problem Continuously

The coverability problem for Petri nets plays a central role in the verification of concurrent shared-memory programs. However, its high EXPSPACE-complete complexity poses a challenge when encountered in real-world instances. In this paper, we develop a new approach to this problem which is primarily based on applying forward coverability in continuous Petri nets as a pruning criterion inside a backward coverability framework. A cornerstone of our approach is the efficient encoding of a recently developed polynomial-time algorithm for reachability in continuous Petri nets into SMT. We demonstrate the effectiveness of our approach on standard benchmarks from the literature, which shows that our approach decides significantly more instances than any existing tool and is in addition often much faster, in particular on large instances.Comment: 18 pages, 4 figure

Preventie van valincidenten bij thuiswonende ouderen: een kostenbesparende interventie?

Nationale en internationale cijfers tonen aan dat 1 op 3 thuiswonende 65-plussers en nagenoeg de helft van de 80-plussers minstens eenmaal per jaar valt. Bij ongeveer 40% van hen resulteert dit in een letsel. Ongeveer 10% van de valpartijen bij ouderen leidt tot ernstige letsels, waaronder heupfracturen (1-2%), andere fracturen (3-5%) en letsels van de weke delen en hoofdtrauma (5%)

La formation d'Herzeele: un nouveau stratotype du pleistocene moyen marin de la mer du Nord

The Herzeele Brickyard (Northern France) offers a permanently well exposed outcrop of continental and marine deposits which are reaching a total thickness of 6 m and are overlying the Ypresian clay of eocene age, occuring at about 8 m N.G.F.Three marine phases represented by tidal flat and brackish sediments may be readily distinguished. The tidal flat sediments have previously been recognized in the area of Izenberge (Belgium) from which locality the name "Izenberge Cardium Sands" has been derived. The marine sediments may be subdivised into units of different lithology: the lower sandy unit, the middle loamy-clayey unit and the upper sandy clayey unit which latter is characterized by the abundance of Cardium edule and Macoma balthica. The marine phases are furthermore separated by continental deposits amongst which peat layers are occurring. The cover sediments are represented by eolian sands and loams interfering with palaeosoils. The series of sediments underlying these cover deposits is named the "Herzeele Formation" which represents a lithostratigraphical unit in the southern North Sea basin. The analysis of the heavy mineral content points to a change in sediment origin occuring after the lower marine sedimentation. The middle and upper marine units contain an increasing content of green hornblende and epidote. Some volcanic minerals were observed at different levels. The clay analyses by means of X-ray diffraction indicate that the different lithostratigraphical units bear polymineralic clay assemblages within which the smectitic fraction is predominant. Greene-Kelly's (1953) Li-test yielded a further detailed analysis of the smectitic components: beidellite, montmorillonite-like. minerals as well as random mixed-layers illite-smectites. The analysis indicates a stratigraphical - mineralogical subdivision of the section which coincides with the lithostratigraphical one.The pollen analytical data show that the whole of the Herzeele Formation most probably belongs to the second half of the Holsteinian interglacial, except for the very base composed of glauconiferous sands. It may readily be seen that the forest evolved from a mesocratic phase, characterized by a Quercetum mixtum with Picea, towards a telocratic phase during which the forest became dominated by Abies. Within the peat which is resting upon the glauconiferous sands, the pollen grains of Taxus, are very abundant in the overlying clay however, this species declines gradually and disappears at the top of the upper marine unit. These evidences are corresponding with the first half of the so-called Abies- zone. Buxus and Vitis, both undergo the same evolution. The only Tertiary relict, Pterocarya, made a short appearance at the top of the upper marine unit, while Azolla filiculoides, was only discovered in the Quercetum zone. The diatom analyses indicate the conditions of brackish and marine sedimentation in a tidal environment. Although the magnetostratigraphical approach of deep-sea and lake sediments has proven to be successful, its application to continental and especially coastal sediments is hampered by the very nature of these sediments (large variation of sedimentation rate, depositional environment, lithology, a.o.) The palaeomagnetical study of the Herzeele Formation reveals a striking difference inmagnetic behaviour between the upper and lower beds separated by the lowermost peat layer. The upper beds are characterized by a strong dispersion of the magnetisation directions and a low intensity. Therefore identification of clear-cut magnetozone(s) is not possible for the moment being. As to the extension of the Herzeele Formation in Belgium, it was only found south of the river Yzer. The comparison with the area of Izenberge itself did not reveal any lithostratigraphical correlation with the Herzeele Formation. The situation of the stratum (former shoreline) at this type-locality gives prove of the importance of the palaeographical evolution since the Lower Pleistocene with the formation of the southern North Sea basin and probably the early opening of the Strait of Dover as well. Therefore this stratum is considered as a landmark and a witness of several interglacial marine transgressions which are attributed to the Holsteinian and to the upper part of the "Cromerian complex"

Use of T2-weighted magnetic resonance imaging of the optic nerve sheath to detect raised intracranial pressure.

INTRODUCTION: The dural sheath surrounding the optic nerve communicates with the subarachnoid space, and distends when intracranial pressure is elevated. Magnetic resonance imaging (MRI) is often performed in patients at risk for raised intracranial pressure (ICP) and can be used to measure precisely the diameter of optic nerve and its sheath. The objective of this study was to assess the relationship between optic nerve sheath diameter (ONSD), as measured using MRI, and ICP. METHODS: We conducted a retrospective blinded analysis of brain MRI images in a prospective cohort of 38 patients requiring ICP monitoring after severe traumatic brain injury (TBI), and in 36 healthy volunteers. ONSD was measured on T2-weighted turbo spin-echo fat-suppressed sequence obtained at 3 Tesla MRI. ICP was measured invasively during the MRI scan via a parenchymal sensor in the TBI patients. RESULTS: Measurement of ONSD was possible in 95% of cases. The ONSD was significantly greater in TBI patients with raised ICP (>20 mmHg; 6.31 +/- 0.50 mm, 19 measures) than in those with ICP of 20 mmHg or less (5.29 +/- 0.48 mm, 26 measures; P < 0.0001) or in healthy volunteers (5.08 +/- 0.52 mm; P < 0.0001). There was a significant relationship between ONSD and ICP (r = 0.71, P < 0.0001). Enlarged ONSD was a robust predictor of raised ICP (area under the receiver operating characteristic curve = 0.94), with a best cut-off of 5.82 mm, corresponding to a negative predictive value of 92%, and to a value of 100% when ONSD was less than 5.30 mm. CONCLUSIONS: When brain MRI is indicated, ONSD measurement on images obtained using routine sequences can provide a quantitative estimate of the likelihood of significant intracranial hypertension

Forward Analysis and Model Checking for Trace Bounded WSTS

We investigate a subclass of well-structured transition systems (WSTS), the bounded---in the sense of Ginsburg and Spanier (Trans. AMS 1964)---complete deterministic ones, which we claim provide an adequate basis for the study of forward analyses as developed by Finkel and Goubault-Larrecq (Logic. Meth. Comput. Sci. 2012). Indeed, we prove that, unlike other conditions considered previously for the termination of forward analysis, boundedness is decidable. Boundedness turns out to be a valuable restriction for WSTS verification, as we show that it further allows to decide all $\omega$-regular properties on the set of infinite traces of the system

Inhibitory Control Across the Preschool Years: Developmental Changes and Associations with Parenting

The normative developmental course of inhibitory control between 2.5 and 6.5 years, and associations with maternal and paternal sensitivity and intrusiveness were tested. The sample consisted of 383 children (52.5% boys). During four annual waves, mothers and fathers reported on their children’s inhibitory control using the Children\u27s Behavior Questionnaire. During the first wave, mothers’ and fathers’ sensitivity and intrusiveness were observed and coded with the Emotional Availability Scales. Inhibitory control exhibited partial scalar invariance over time, and increased in a decelerating rate. For both mothers and fathers, higher levels of sensitivity were associated with a higher initial level of children\u27s inhibitory control, whereas higher levels of intrusiveness predicted a slower increase in children\u27s inhibitory control

Dynamic Changes in White Matter Abnormalities Correlate With Late Improvement and Deterioration Following TBI: A Diffusion Tensor Imaging Study.

OBJECTIVE: Traumatic brain injury (TBI) is not a single insult with monophasic resolution, but a chronic disease, with dynamic processes that remain active for years. We aimed to assess patient trajectories over the entire disease narrative, from ictus to late outcome. METHODS: Twelve patients with moderate-to-severe TBI underwent magnetic resonance imaging in the acute phase (within 1 week of injury) and twice in the chronic phase of injury (median 7 and 21 months), with some undergoing imaging at up to 2 additional time points. Longitudinal imaging changes were assessed using structural volumetry, deterministic tractography, voxel-based diffusion tensor analysis, and region of interest analyses (including corpus callosum, parasagittal white matter, and thalamus). Imaging changes were related to behavior. RESULTS: Changes in structural volumes, fractional anisotropy, and mean diffusivity continued for months to years postictus. Changes in diffusion tensor imaging were driven by increases in both axial and radial diffusivity except for the earliest time point, and were associated with changes in reaction time and performance in a visual memory and learning task (paired associates learning). Dynamic structural changes after TBI can be detected using diffusion tensor imaging and could explain changes in behavior. CONCLUSIONS: These data can provide further insight into early and late pathophysiology, and begin to provide a framework that allows magnetic resonance imaging to be used as an imaging biomarker of therapy response. Knowledge of the temporal pattern of changes in TBI patient populations also provides a contextual framework for assessing imaging changes in individuals at any given time point

Successful optic nerve regeneration in the senescent zebrafish despite age-related decline of cell intrinsic and extrinsic response processes

Dysfunction of the central nervous system (CNS) in neurodegenerative diseases or after brain lesions seriously affects life quality of a growing number of elderly, since the adult CNS lacks the capacity to replace or repair damaged neurons. Despite intensive research efforts, full functional recovery after CNS disease and/or injury remains challenging, especially in an aging environment. As such, there is a rising need for an aging model in which the impact of aging on successful regeneration can be studied. Here, we introduce the senescent zebrafish retinotectal system as a valuable model to elucidate the cellular and molecular processes underlying age-related decline in axonal regeneration capacities. We found both intrinsic and extrinsic response processes to be altered in aged fish. Indeed, expression levels of growth-associated genes are reduced in naive and crushed retinas, and the injury-associated increase in innate immune cell density appears delayed, suggesting retinal inflammaging in old fish. Strikingly, however, despite a clear deceleration in regeneration onset and early axon outgrowth leading to an overall slowing of optic nerve regeneration, reinnervation of the optic tectum and recovery of visual function occurs successfully in the aged zebrafish retinotectal system

Small business economics: A perspective from The Netherlands

In the analysis of economic phenomena either within or across industries there is room for integrating the role of small business. This contribution can be made by aggregation or generalization of the findings at the meso level, which again are partly based upon analyses at the micro level. The Netherlands has a long history in macro model building. A recent discussion among Dutch macro-economists considered the future of econometric model building at the macro level, and considered how best to improve this model building. The explicit integration of scale effects, however, was not mentioned. I am convinced that improvements in this respect are possible. In particular, I have in mind the role which small businesses play in certain areas such as wage structure, employment or investments. The dissection of macro prognoses into a small business component and a remaining component is a traditional practice in The Netherlands.1 Finally, there is much concern in The Netherlands for the calculation of regulatory effects, decomposed into effects for small and large businesses. If anywhere in the world there is a solid foundation for studying scale effects in both macro and sectoral models, it most certainly has been in The Netherlands. There is a strong tradition of macro-econometric model building; groups of econometricians specialized in small business research exist; Dutch policymakers show concern and the required research apparatus is available