Approximate Compliance Checking for Annotated Process Models

We describe a method for validating whether the states reached by a process are compliant with a set of constraints. This serves to (i) check the compliance of a new or altered process against the constraints base, and (ii) check the whole process repository against a changed constraints base, e.g., when new regulations come into being. For these purposes we formalize a particular class of compliance rules as well as annotated process models, the latter by combining a notion from the workflow literature with a notion from the AI actions and change literature. The compliance rules in turn pose restrictions on the desirable states. Each rule takes the form of a clausal constraint, i.e., a disjunction of literals. If for a given state there is a grounded clause none of whose literals are true, then the constraint is violated and indicates non-compliance. Checking whether a process is compliant with the rules involves enumerating all reachable states and is in general a hard search problem. Since long waiting times during process modelling are undesirable, it is important to explore restricted classes and approximate methods. We present a polynomial-time algorithm that, for a particular class of processes, computes the sets of literals that are necessarily true at particular points during process execution. Based on this information, we devise two approximate compliance checking methods. One of these is sound but not complete (it guarantees to find only non-compliance instances, but not to find all non-compliance instances); the other method is complete but not sound. We sketch how one can trace the state evolution back to the process activities which caused the (potential) non-compliance, and hence provide the user with some error diagnosis

Complexes of oppositely charged polyelectrolytes and surfactants - recent developments in the field of biologically derived polyelectrolytes

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.We review the work done on complexes between biopolyelectrolytes such as ionically modified cellulose or chitosan and oppositely charged surfactants. Around equimolarity of the charges one typically observes precipitation but for other mixing ratios one may form long-time stable complexes, where structure and rheology depend on the mixing ratio, total concentration and the molecular constitution of the components. In addition, it may be the case that the structures are formed under non-equilibrium situations and therefore depend on the preparation path. The binding is shown to occur cooperatively and the micelles present often retain their shape irrespective of the complexation. However, the rather stiff biopolyelectrolytes may lead to an interconnection between different aggregates thereby forming a network with the corresponding rheological properties. In general, the structure and the properties of the aggregates are rather versatile and correspondingly one can create a wide range of different surfactant–biopolyelectrolyte systems by appropriately choosing the composition. This is very interesting as it allows for formulations with a large range of tuneable properties with ecologically friendly polyelectrolytes for many relevant applications.BMBF, 05K10KT1, NanoSOFT: Teilprojekt 2: Neutronen Spin-Echo Experimente zur Untersuchung komplexer Soft-Matter Systeme mit extremer Präzissio

On the experimental verification of the uncertainty principle of position and momentum

Historically, Kennard was the first to choose the standard deviation as a quantitative measure of uncertainty, and neither he nor Heisenberg explicitly explained why this choice should be appropriate from the experimental physical point of view. If a particle is prepared by a single slit of spatial width $\Delta x$, it has been shown that a finite standard deviation $\sigma_p<\infty$ can only be ensured if the wave-function is zero at the edge of $\Delta x$, otherwise it does not exist. Under this circumstances the corresponding sharp inequality is $\sigma_p\Delta x\geq \pi\hbar$. This bound will be reconsidered from the mathematical point of view in terms of a variational problem in Hilbert space and will furthermore be tested in a 4f-single slit diffraction experiment of a laser beam. Our results will be compared with a laser-experiment recently given by M. F. Guasti (2022)

Measuring the bending rigidity of microbial glucolipid (biosurfactant) bioamphiphile self-assembled structures by neutron spin-echo (NSE): interdigitated vesicles, lamellae and fibers

Bending rigidity, k, is classically measured for lipid membranes to characterize their nanoscale mechanical properties as a function of composition. Widely employed as a comparative tool, it helps understanding the relationship between the lipid's molecular structure and the elastic properties of its corresponding bilayer. Widely measured for phospholipid membranes in the shape of giant unilamellar vesicles (GUVs), bending rigidity is determined here for three self-assembled structures formed by a new biobased glucolipid bioamphiphile, rather associated to the family of glycolipid biosurfactants than phospholipids. In its oleyl form, glucolipid G-C18:1 can assemble into vesicles or crystalline fibers, while in its stearyl form, glucolipid G-C18:0 can assemble into lamellar gels. Neutron spin-echo (NSE) is employed in the q-range between 0.3 nm-1 (21 nm) and 1.5 nm-1 (4.1 nm) with a spin-echo time in the range of up to 500 ns to characterize the bending rigidity of three different structures (Vesicle suspension, Lamellar gel, Fiber gel) solely composed of a single glucolipid. The low (k= 0.30 $\pm$ 0.04 kbT) values found for the Vesicle suspension and high values found for the Lamellar (k= 130 $\pm$ 40 kbT) and Fiber gels (k= 900 $\pm$ 500 kbT) are unusual when compared to most phospholipid membranes. By attempting to quantify for the first time the bending rigidity of self-assembled bioamphiphiles, this work not only contributes to the fundamental understanding of these new molecular systems, but it also opens new perspectives in their integration in the field of soft materials

Dynamics of small unilamellar vesicles

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Chem. Phys. 148, 104901 (2018) and may be found at https://doi.org/10.1063/1.5009424.In this paper, we investigate the dynamics of small unilamellar vesicles with the aid of neutron spin-echo spectroscopy. The purpose of this investigation is twofold. On the one hand, we investigate the influence of solubilised cosurfactant on the dynamics of the vesicle’s surfactant bilayer. On the other hand, the small unilamellar vesicles used here have a size between larger vesicles, with dynamics being well described by the Zilman-Granek model and smaller microemulsion droplets which can be described by the Milner-Safran model. Therefore, we want to elucidate the question, which model is more suitable for the description of the membrane dynamics of small vesicles, where the finite curvature of the bilayer is felt by the contained amphiphilic molecules. This question is of substantial relevance for our understanding of membranes and how their dynamics is affected by curvature, a problem that is also of key importance in a number of biological questions. Our results indicate the even down to vesicle radii of 20 nm the Zilman-Granek model appears to be the more suitable one.BMBF, 05K13KT1, Probenumgebung und paralle Charakterisierung bei hochpräzisen Neutronen Spin-Echo (NSE) Messungen an komplexen Systemen der weichen Materi

Detecting regulatory compliance for business process models through semantic annotations

A given business process may face a large number of regulatory obligations the process may or comply with. Providing tools and techniques through which an evaluation of the compliance degree of a given process can be undertaken is seen as a key objective in emerging business process platforms. We address this problem through a diagnostic framework that provides the ability to assess the compliance gaps present in a given process. Checking whether a process is compliant with the rules involves enumerating all reachable states and is hence, in general, a hard search problem. The approach taken here allows to provide useful diagnostic information in polynomial time. The approach is based on two underlying techniques. A conceptually faithful representation for regulatory obligations is firstly provided by a formal rule language based on a non-monotonic deontic logic of violations. Secondly, processes are formalized through semantic annotations that allow a logical state space to be created. The intersection of the two allows us to devise an efficient method to detect compliance gaps; the method guarantees to detect all obligations that will necessarily arise during execution, but that will not necessarily be fulfilled