Fragmentation Phase Transition in Atomic Clusters II - Coulomb Explosion of Metal Clusters -

We discuss the role and the treatment of polarization effects in many-body systems of charged conducting clusters and apply this to the statistical fragmentation of Na-clusters. We see a first order microcanonical phase transition in the fragmentation of $Na^{Z+}_{70}$ for Z=0 to 8. We can distinguish two fragmentation phases, namely evaporation of large particles from a large residue and a complete decay into small fragments only. Charging the cluster shifts the transition to lower excitation energies and forces the transition to disappear for charges higher than Z=8. At very high charges the fragmentation phase transition no longer occurs because the cluster Coulomb-explodes into small fragments even at excitation energy $\epsilon^* = 0$.Comment: 19 text pages +18 *.eps figures, my e-mail adress: [email protected] submitted to Z. Phys.

Quark-Gluon-Plasma Formation at SPS Energies?

By colliding ultrarelativistic ions, one achieves presently energy densities close to the critical value, concerning the formation of a quark-gluon-plasma. This indicates the importance of fluctuations and the necessity to go beyond the investigation of average events. Therefore, we introduce a percolation approach to model the final stage ($\tau > 1$ fm/c) of ion-ion collisions, the initial stage being treated by well-established methods, based on strings and Pomerons. The percolation approach amounts to finding high density domains, and treating them as quark-matter droplets. In this way, we have a {\bf realistic, microscopic, and Monte--Carlo based model which allows for the formation of quark matter.} We find that even at SPS energies large quark-matter droplets are formed -- at a low rate though. In other words: large quark-matter droplets are formed due to geometrical fluctuation, but not in the average event.Comment: 7 Pages, HD-TVP-94-6 (1 uuencoded figure

Student evaluation of teaching effectiveness: implications for scholars in operations management

Many times, teaching rating by students are the most influential measure of the quality of teaching departments, courses and teachers to assess how curricula changes are perceived by students. This study seeks biases introduced by background variables. If these are relevant, then student evaluations as a valid indicator of teaching effectiveness for the purpose of quality improvement and assurance could be questioned. The research purpose is (i) to appreciate the suitability of business student ratings in assessing teaching performance, and (ii) to explore limitations of current practices considering student evaluation as a primary university tool to assess teaching effectiveness.info:eu-repo/semantics/acceptedVersio

Developing a research agenda for digital accessibility in multinational enterprises

Digital accessibility for disabled people is a hot topic of Corporate Social Responsibility, mandatory under current UN and UE dispositions. This research aims at investigating its company-wide administrative integration by developing a systematic process of enquiry producing a diagnosis tool under the guidance of the Soft Systems Methodology (RQ3). Absorptive capacity provided the theoretical umbrella for structuring the problem-situation (RQ1) by setting its Root Definitions. Thus, the expected scientifically supported diagnosing tool should generate feasible and desirable changes to the problem-situation perceptions (RQ2). Digital Accessibility by Design in Service was coined to define this innovative and relevant approach.info:eu-repo/semantics/acceptedVersio

Digital accessibility in multinational enterprises: A meta study

Ever since the ratification of Directive 2016/2102 (Web Accessibility Directive) and EU Directive 2019/882 (European Accessibility Act), digital accessibility has been gaining in importance for public administration and business within the European Union. Furthermore, the role of companies has changed during the last decades and the concept of corporate social responsibility has become increasingly relevant for multinational enterprises. As one aspect of Corporate Social Responsibility, digital accessibility can bring a lot of advantages, for example by driving innovation or by enhancing a company's brand. Therefore, even companies that do not have to meet legal requirements should act with digital accessibility in mind as one part of their Corporate Social Responsibility Strategy. In the current literature and legal regulations, digital accessibility is mostly described as a technical issue, while organizational, structural aspects, and managerial tasks within the implementation of digital accessibility are ignored. By reviewing current literature, this meta-study shows the relevance of digital accessibility for multinational companies, explains why the implementation of digital accessibility cannot only be considered from a technical point of view and discusses initial approaches to examine the integration of digital accessibility into company-wide processes.info:eu-repo/semantics/publishedVersio

Kernel Bounds for Structural Parameterizations of Pathwidth

Assuming the AND-distillation conjecture, the Pathwidth problem of determining whether a given graph G has pathwidth at most k admits no polynomial kernelization with respect to k. The present work studies the existence of polynomial kernels for Pathwidth with respect to other, structural, parameters. Our main result is that, unless NP is in coNP/poly, Pathwidth admits no polynomial kernelization even when parameterized by the vertex deletion distance to a clique, by giving a cross-composition from Cutwidth. The cross-composition works also for Treewidth, improving over previous lower bounds by the present authors. For Pathwidth, our result rules out polynomial kernels with respect to the distance to various classes of polynomial-time solvable inputs, like interval or cluster graphs. This leads to the question whether there are nontrivial structural parameters for which Pathwidth does admit a polynomial kernelization. To answer this, we give a collection of graph reduction rules that are safe for Pathwidth. We analyze the success of these results and obtain polynomial kernelizations with respect to the following parameters: the size of a vertex cover of the graph, the vertex deletion distance to a graph where each connected component is a star, and the vertex deletion distance to a graph where each connected component has at most c vertices.Comment: This paper contains the proofs omitted from the extended abstract published in the proceedings of Algorithm Theory - SWAT 2012 - 13th Scandinavian Symposium and Workshops, Helsinki, Finland, July 4-6, 201

Definition of key drivers for project success regarding the General Data Protection Regulation

In the context of the General Data Protection Regulation (GDPR), organisational governance must consider data privacy concerns and regulations. This will avoid illegal situations, the related fines, damage to organisational reputation or, even, temporary/definitive limitation on processing activities. An innovative conceptual model is proposed to deliver the necessary change that addresses GDPR concerns based on the enablers concept. Moreover, project success is (re)examined to include stakeholders perceptions, in addition to organisational effectiveness, which is defined by the respect for legal requirements and by demonstration of compliance with the Regulation at an acceptable cost, i.e. the typical internal deliverables.info:eu-repo/semantics/acceptedVersio

Cluster Editing: Kernelization based on Edge Cuts

Kernelization algorithms for the {\sc cluster editing} problem have been a popular topic in the recent research in parameterized computation. Thus far most kernelization algorithms for this problem are based on the concept of {\it critical cliques}. In this paper, we present new observations and new techniques for the study of kernelization algorithms for the {\sc cluster editing} problem. Our techniques are based on the study of the relationship between {\sc cluster editing} and graph edge-cuts. As an application, we present an ${\cal O}(n^2)$-time algorithm that constructs a $2k$ kernel for the {\it weighted} version of the {\sc cluster editing} problem. Our result meets the best kernel size for the unweighted version for the {\sc cluster editing} problem, and significantly improves the previous best kernel of quadratic size for the weighted version of the problem

On the stable degree of graphs

We define the stable degree s(G) of a graph G by s(G)∈=∈ min max d (v), where the minimum is taken over all maximal independent sets U of G. For this new parameter we prove the following. Deciding whether a graph has stable degree at most k is NP-complete for every fixed k∈≥∈3; and the stable degree is hard to approximate. For asteroidal triple-free graphs and graphs of bounded asteroidal number the stable degree can be computed in polynomial time. For graphs in these classes the treewidth is bounded from below and above in terms of the stable degree