Central limit theorems for Poisson hyperplane tessellations

We derive a central limit theorem for the number of vertices of convex polytopes induced by stationary Poisson hyperplane processes in $\mathbb{R}^d$. This result generalizes an earlier one proved by Paroux [Adv. in Appl. Probab. 30 (1998) 640--656] for intersection points of motion-invariant Poisson line processes in $\mathbb{R}^2$. Our proof is based on Hoeffding's decomposition of $U$-statistics which seems to be more efficient and adequate to tackle the higher-dimensional case than the ``method of moments'' used in [Adv. in Appl. Probab. 30 (1998) 640--656] to treat the case $d=2$. Moreover, we extend our central limit theorem in several directions. First we consider $k$-flat processes induced by Poisson hyperplane processes in $\mathbb{R}^d$ for $0\le k\le d-1$. Second we derive (asymptotic) confidence intervals for the intensities of these $k$-flat processes and, third, we prove multivariate central limit theorems for the $d$-dimensional joint vectors of numbers of $k$-flats and their $k$-volumes, respectively, in an increasing spherical region.Comment: Published at http://dx.doi.org/10.1214/105051606000000033 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Comorbidities of patients in tiotropium clinical trials : comparison with observational studies of patients with chronic obstructive pulmonary disease

Acknowledgments The authors are fully responsible for all content and editorial decisions made, were involved at all stages of manuscript development, and have approved the final version for publication. Editorial assistance, supported financially by Boehringer Ingelheim and Pfizer, was provided by Godfrey Lisk of PAREXEL International during the preparation of this manuscript. This work is published by Dove Medical Press Limited, and licensed under Creative Commons Attribution - Non Commercial (unported, v3.0) License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited.Peer reviewedPublisher PD

Density functional theory for colloidal mixtures of hard platelets, rods, and spheres

A geometry-based density functional theory is presented for mixtures of hard spheres, hard needles and hard platelets; both the needles and the platelets are taken to be of vanishing thickness. Geometrical weight functions that are characteristic for each species are given and it is shown how convolutions of pairs of weight functions recover each Mayer bond of the ternary mixture and hence ensure the correct second virial expansion of the excess free energy functional. The case of sphere-platelet overlap relies on the same approximation as does Rosenfeld's functional for strictly two-dimensional hard disks. We explicitly control contributions to the excess free energy that are of third order in density. Analytic expressions relevant for the application of the theory to states with planar translational and cylindrical rotational symmetry, e.g. to describe behavior at planar smooth walls, are given. For binary sphere-platelet mixtures, in the appropriate limit of small platelet densities, the theory differs from that used in a recent treatment [L. Harnau and S. Dietrich, Phys. Rev. E 71, 011504 (2004)]. As a test case of our approach we consider the isotropic-nematic bulk transition of pure hard platelets, which we find to be weakly first order, with values for the coexistence densities and the nematic order parameter that compare well with simulation results.Comment: 39 pages, 8 figure

How AI Developers’ Perceived Accountability Shapes Their AI Design Decisions

While designing artificial intelligence (AI)-based systems, AI developers usually have to justify their design decisions and, thus, are accountable for their actions and how they design AI-based systems. Crucial facets of AI (i.e., autonomy, inscrutability, and learning) notably cause potential accountability issues that AI developers must consider in their design decisions, which has received little attention in prior literature. Drawing on self-determination theory and accountability literature, we conducted a scenario-based survey (n=132). We show that AI developers who perceive themselves as accountable tend to design AI-based systems to be less autonomous and inscrutable but more capable of learning when deployed. Our mediation analyses suggest that perceived job autonomy can partially explain these direct effects. Therefore, AI design decisions depend on individual and organizational settings and must be considered from different perspectives. Thus, we contribute to a better understanding of the effects of AI developers’ perceived accountability when designing AI-based systems

Give me 3W1H: A Bibliometric View on Accountable AI

Accountability is crucial to make stakeholders of Artificial Intelligence (AI)-based systems justify their actions, thereby explaining the harm such systems cause to AI users. Due to the importance of accountability in the context of AI, accountability was introduced into IS research through literature reviews. Therefore, while IS research’s understanding of accountability covers the necessary depth, it comes at the expense of its essential breadth. Using a bibliometric analysis with 19,978 English-language papers, we shed light on the essential breadth posing three W- and one H-questions (When, What, Whereof, and How). Therefore, we contribute to IS research by highlighting the urgent need to revise existing definitions of accountability in the context of AI and establish them in IS research. We argue that a missing revision leads to non-transferrable findings within IS research. Accordingly, this study serves as a starting point for adapting definitions and creating a shared understanding in IS research

Charakterisierung sekretorischer Lysosomen aus humanen T- und NK-Zellen

Zytotoxische T-Zellen und natürliche Killerzellen eliminieren entartete oder virusinfizierte Zellen durch gezielte Freisetzung zytotoxischer Effektormoleküle aus sogenannten sekretorischen Lysosomen. In der vorliegenden Arbeit wurde eine Methodik zur Anreicherung intakter Organellen etabliert, die eine genauere Charakterisierung dieses Kompartimentes erlaubte. Mittels zwei-dimensionaler differentieller Gelelektrophorese (2D-DIGE) konnte das luminale Proteom sekretorischer Lysosomen verschiedener zytotoxischer Effektorzellen kartiert und mit einander verglichen werden. Darüber hinaus wurden Untersuchungen zur Reifung der sekretorschen Lysosomen sowie zur subzellulären Verteilung zytotoxischer Effektorproteine durchgeführt, die Hinweise auf unterschiedliche zytotoxische Effektor-Granula ergaben

Knowledge Worker Roles and Actions - Results of Two Empirical Studies

Reinhardt, W., Schmidt, B., Sloep, P. B., & Drachsler, H. (2011). Knowledge Worker Roles and Actions - Results of Two Empirical Studies. Knowledge and Process Management, 18(3), 150–174. doi: 10.1002/kpm.378 Online: http://onlinelibrary.wiley.com/doi/10.1002/kpm.378/abstractThis paper proposes a typology of knowledge workers and their respective knowledge actions. The extant literature on the definition of knowledge work actions is examined and evaluated. The existing classifications of roles of knowledge workers are evaluated and extended with additional literature and empirical findings definition of a typology of knowledge worker roles. The empirical data in this paper comes from two studies. In the Task Execution Study 20 knowledge worker had to carry out a selection of prepared tasks. The computer system that the participants were using was equipped with sensors, so the execution steps of the tasks could be traced and analyzed. The data from the second study comes from a questionnaire survey of knowledge workers, which yielded 43 responses. The paper shows that the sampled users take on all identified knowledge worker roles and that the knowledge work actions can be recognized in the sensor data from the first study. This paper contributes to the literature by proposing a new way of classifying the roles of knowledge workers and the knowledge actions they perform during their daily work. Furthermore, the paper provides a preliminary understanding of the relation between knowledge-intense work tasks, the roles they are executed in and the tools that are used to accomplish the respective tasks.The work presented in this paper has been partly funded by the German Federal Ministry of Education and Research under grant no. 01IA08006