620 research outputs found
On determining the AND-OR hierarchy in workflow nets
This paper presents a notion of reduction where a WF net is transformed into a smaller net by iteratively contracting certain well-formed subnets into single nodes until no more of such contractions are possible. This reduction can reveal the hierarchical structure of a WF net, and since it preserves certain semantic properties such as soundness, can help with analysing and understanding why a WF net is sound or not. The reduction can also be used to verify if a WF net is an AND-OR net. This class of WF nets was introduced in earlier work, and arguably describes nets that follow good hierarchical design principles.
It is shown that the reduction is confluent up to isomorphism, which means that despite the inherent non-determinism that comes from the choice of subnets that are contracted, the final result of the reduction is always the same up to the choice of the identity of the nodes. Based on this result, a polynomial-time algorithm is presented that computes this unique result of the reduction. Finally, it is shown how this algorithm can be used to verify if a WF net is an AND-OR net
Centrum Międzynarodowego Szkolenia Bibliotekarzy im. Waltera i Gerdy Mortensonów : międzynarodowe bibliotekarstwo w zmieniającym się świecie
The Mortenson Center for International Library Programs, established in 1991 at the University of Illinois
at Urbana-Champaign, has welcomed more than 700 librarians from 89 countries to participate in its educational and professional development programs. The main purpose of various programs and projects developed by the Center is to provide continuing education for librarians, which may assist in overcoming cultural and educational inequalities occurring in developing countries, and fosters international cooperation in the area of library services and library education. The paper will discuss the Center's mission and its changing focus, the most distinguished programs and projects, LIS mini-courses especially geared towards Mortenson associates, and the Mortenson Center cooperation with other foundations in the area of funding the Center's programs. The Center's activities and management will be examined as possible models for a successful international cooperation between library educators and professionals.Z oferty edukacyjnej The Mortenson Center for International Library Programs, które zostało założone
w 1991 roku na University of Illinois at Urbana-Champaign, skorzystało do tej pory ponad 700 bibliotekarzy z 89 krajów. Głównym celem różnych programów i projektów realizowanych przez tę instytucję było rozwijanie edukacji permanentnej dla bibliotekarzy, która mogłaby pomagać w przełamywaniu kulturalnych i edukacyjnych nierówności w krajach rozwijających się oraz wspierać rozwój międzynarodowej współpracy w obszarze usług bibliotecznych i edukacji bibliotekarskiej. Przedstawiono misję Centrum i jego zmieniający się główny obszar zainteresowań, najważniejsze programy i projekty, mini-kursy z zakresu informacji naukowej i bibliotekoznawstwa zaprojektowane specjalnie dla "członków Centrum" oraz współpracę w zakresie finansowania programów oferowanych przez Centrum. Działania Centrum i sposób zarządzania zostały przeanalizowane pod kątem możliwości ich wykorzystania jako skutecznych i sprawdzonych modeli realizowania współpracy międzynarodowej między edukatorami
z zakresu bibliotekarstwa i profesjonalistami
Simplicial bounded cohomology and stability
We introduce a set of combinatorial techniques for studying the simplicial
bounded cohomology of semi-simplicial sets, simplicial complexes and posets. We
apply these methods to prove several new bounded acyclicity results for
semi-simplicial sets appearing in the homological stability literature. Our
strategy is to recast classical arguments (due to Bestvina, Maazen, van der
Kallen, Vogtmann, Charney and, recently, Galatius--Randal-Williams) in the
setting of bounded cohomology using uniformly bounded refinements of well-known
simplicial tools. Combined with ideas developed by Monod and De la Cruz
Mengual--Hartnick, we deduce slope- stability results for the bounded
cohomology of two large classes of linear groups: general linear groups over
any ring with finite Bass stable rank and certain automorphism groups of
quadratic modules over the integers or any field of characteristic zero. We
expect that many other results in the literature on homological stability admit
bounded cohomological analogues by applying the blueprint provided in this
work.Comment: 53 pages. Comments welcome
Apartment classes of integral symplectic groups
In this note we present an alternative proof of a theorem of Gunnells, which
states that the Steinberg module of is a
cyclic -module, generated by integral
apartment classes.Comment: 16 pages. Comments welcome
Coopetition as a development stimulator of enterprises in the networked steel sector
The article deals with the problems of coopetition, i.e. simultaneous cooperation and competition between enterprises. This phenomenon is becoming more and more common in the steel industry, initially in the dimension of individual alliances, and currently it takes a form of network connections. The different groups of enterprises are involved in these networks: global players, regional champions, as well as niche specialists. Through the coopetition companies achieve benefits (both internal and external) which are becoming the stimulator of survival and growth in a highly competitive steel industry
Phosphorylation and Ubiquitylation Regulate Protein Trafficking, Signaling, and the Biogenesis of Primary Cilia
The primary cilium is a solitary, microtubule-based membrane protrusion extending from the surface of quiescent cells that senses the cellular environment and triggers specific cellular responses. The functions of primary cilia require not only numerous different components but also their regulated interplay. The cilium performs highly dynamic processes, such as cell cycle-dependent assembly and disassembly as well as delivery, modification, and removal of signaling components to perceive and process external signals. On a molecular level, these processes often rely on a stringent control of key modulatory proteins, of which the activity, localization, and stability are regulated by post-translational modifications (PTMs). While an increasing number of PTMs on ciliary components are being revealed, our knowledge on the identity of the modifying enzymes and their modulation is still limited. Here, we highlight recent findings on cilia-specific phosphorylation and ubiquitylation events. Shedding new light onto the molecular mechanisms that regulate the sensitive equilibrium required to maintain and remodel primary cilia functions, we discuss their implications for cilia biogenesis, protein trafficking, and cilia signaling processes
Work Cycle of Internal Combustion Engine Due to Rightsizing
It is worth still working on the development of the internal combustion engine, because its time was not yet over. This was demonstrated by the author’s review of the literature, indicating at least the perspective of 2050 the universality of the engine as the primary propulsion or support in hybrid transport units. The presented considerations may have a broader perspective, when the thermodynamic problems of a thermal machine such as an internal combustion engine are indicated. This chapter deals with the issues of changing the swept volume known as downsizing/rightsizing. An equivalent swept volume was introduced, defined by the coefficients determining changes in the cylinder diameter and the stroke of the piston. An attempt was made to find the mutual relations to the efficiency of the work cycle and engine operating parameters. The research methodology was proposed as a mix of laboratory tests and theoretical analyses, on the basis of which it was established that while maintaining the same value of the downsizing index, despite the various permissible combinations of cylinder diameter and piston stroke changes, the cycle efficiency remains unchanged. The engine operating parameters are changing, resulting from the use of support systems for rightsizing geometric changes
The thickness of the ventral midline of the spinal cord in human embryos during the fifth week
The thickness of the ventral midline of the spinal cord was determined in
9 human embryos aged five weeks (developmental stages 13-15). This part of
the spinal cord consists of floor plate, mantle and marginal layers. The floor
plate ependymal cells form pseudostratified columnar epithelium. The thickness
of the investigated structure varied from 20 to 50 micrometers at different
levels of the spinal cord
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