Expressiveness and Completeness in Abstraction

We study two notions of expressiveness, which have appeared in abstraction theory for model checking, and find them incomparable in general. In particular, we show that according to the most widely used notion, the class of Kripke Modal Transition Systems is strictly less expressive than the class of Generalised Kripke Modal Transition Systems (a generalised variant of Kripke Modal Transition Systems equipped with hypertransitions). Furthermore, we investigate the ability of an abstraction framework to prove a formula with a finite abstract model, a property known as completeness. We address the issue of completeness from a general perspective: the way it depends on certain abstraction parameters, as well as its relationship with expressiveness.Comment: In Proceedings EXPRESS/SOS 2012, arXiv:1208.244

An Analysis of the Effectiveness of E-Commerce at United Parcel Service

This paper is an analysis of e-commerce at United Parcel Service (NYSE: UPS). The paper begins with a general overview of the company’s IT environment to establish awareness of the size and complexity of this corporation. The analysis includes a macro level breakdown of the technology infrastructure of UPS ranging from the amount of data centers the company has, to the amount of PCs currently in operation. The study also more closely analyzes the software and database structure of UPS. Furthermore, an analysis of the company’s E-commerce activities was conducted and includes an interview with Tom Creech, the North Florida District E-commerce manager at UPS. Finally, research was conducted to evaluate the emerging technologies that UPS will soon be implementing and should be employing in the future to support the business strategy and maintain its competitive edge

Preparations for a Brexit: views from Denmark, Italy, the Netherlands, Slovenia and Spain

If Britain votes to leave the EU it will have to negotiate its exit and a new post-withdrawal relationship with the EU, one that will have to be agreed by the remaining 27 EU member states and the European Parliament. What positions might they take in the negotiations? Over the next few weeks the LSE’s BrexitVote blog will be running a series of overviews from each member state and the European Parliament setting out what positions they might take. Written by authors based at universities and research institutions across Europe, and compiled by the LSE’s Tim Oliver, the overviews build on his introductory piece which sets out the various negotiations the EU will undertake in the event of a British exit. This post is the first in the series and gives views from Denmark, Italy, the Netherlands, Slovenia and Spain

External Tank (ET) Bipod Fitting Bolted Attachment Locking Insert Performance

Following STS-107, the External Tank (ET) Project implemented corrective actions and configuration changes at the ET bipod fitting. Among the corrective actions, the existing bolt lock wire which provided resistance to potential bolt rotation was removed. The lock wire removal was because of concerns with creating voids during foam application and potential for lock wire to become debris. The bolts had been previously lubricated to facilitate assembly but, because of elimination of the lock wire, the ET Project wanted to enable the locking feature of the insert. Thus, the lubrication was removed from bolt threads and instead applied to the washer under the bolt head. Lubrication is necessary to maximize joint pre-load while remaining within the bolt torque specification. The locking feature is implemented by thread crimping in at four places in the insert. As the bolt is torqued into the insert the bolt threads its way past the crimped parts of the insert. This provides the locking of the bolt, as torque is required to loosen the joint after clamping

Mesenchymal Cells Affect Salivary Epithelial Cell Morphology on PGS/PLGA Core/Shell Nanofibers

Engineering salivary glands is of interest due to the damaging effects of radiation therapy and the autoimmune disease Sjögren’s syndrome on salivary gland function. One of the current problems in tissue engineering is that in vitro studies often fail to predict in vivo regeneration due to failure of cells to interact with scaffolds and of the single cell types that are typically used for these studies. Although poly (lactic co glycolic acid) (PLGA) nanofiber scaffolds have been used for in vitro growth of epithelial cells, PLGA has low compliance and cells do not penetrate the scaffolds. Using a core-shell electrospinning technique, we incorporated poly (glycerol sebacate) (PGS) into PLGA scaffolds to increase the compliance and decrease hydrophobicity. PGS/PLGA scaffolds promoted epithelial cell penetration into the scaffold and apical localization of tight junction proteins, which is necessary for epithelial cell function. Additionally, co-culture of the salivary epithelial cells with NIH3T3 mesenchymal cells on PGS/PLGA scaffolds facilitated epithelial tissue reorganization and apical localization of tight junction proteins significantly more than in the absence of the mesenchyme. These data demonstrate the applicability of PGS/PLGA nanofibers for epithelial cell self-organization and facilitation of co-culture cell interactions that promote tissue self-organization in vitro