3,451 research outputs found
Self-organized critical and synchronized states in a nonequilibrium percolation model
We introduce a nonequilibrium percolation model which shows a self-organized
critical (SOC) state and several periodic states. In the SOC state, the
correlation length diverges slower than the system size, and the corresponding
exponent depends non universally on the parameter of the model. The periodic
states contain an infinite cluster covering only part of the system.Comment: 10 pages, Revtex, two uuencoded figure
Rhetoric of landscape architecture and interior design discourses: preparation for cross-disciplinary practice
In the current reform context, the uniqueness of local disciplinary practices is being forgotten in the race towards cross-disciplinary practice. The rhetoric of the pedagogic discourses of landscape architectural students and interior design students is described as part of a doctoral study undertaken to document practices and orientations prior to cross-disciplinary collaboration. We draw on the theoretical framework of Bernstein and the rhetorical method of Burke to study the grammars of 'landscape' representation employed within these disciplinary examples. We offer a method of investigating how prepared final year students may be for working in a cross-disciplinary manner. The discursive interactions of their work, as illustrated by four examples of drawn images and written text, are described. Comparisons of these examples show both similarities and differences in the students' grammars of representation within their disciplines. Furthermore, however, the findings suggest a progressive weakening of the grammars of the pedagogic discourses that apply to the concepts and procedures of both disciplines. This poses some key issues for educators. It is argued that while weak grammars foster students' deeper understanding of concepts, they also weaken the pedagogic identity and autonomy of their discipline. Strong grammars resist domination and subordination, ensuring the ongoing relative autonomy of a discipline
Finite-size effects in the self-organized critical forest-fire model
We study finite-size effects in the self-organized critical forest-fire model
by numerically evaluating the tree density and the fire size distribution. The
results show that this model does not display the finite-size scaling seen in
conventional critical systems. Rather, the system is composed of relatively
homogeneous patches of different tree densities, leading to two qualitatively
different types of fires: those that span an entire patch and those that don't.
As the system size becomes smaller, the system contains less patches, and
finally becomes homogeneous, with large density fluctuations in time.Comment: 10 pages, 11 figure
Review of \u3cem\u3eGuest Workers and Resistance to U.S. Corporate Despotism.\u3c/em\u3e Immanuel Ness. Reviewed by Barbara Franz.
Book review of Immanuel Ness, Guest Workers and Resistance to U.S. Corporate Despotism, University of Illinois Press (2011). 25.00 (paperback)
Doppler sonography of the uterine and the cubital arteries in normal pregnancies, preeclampsia and intrauterine growth restriction: evidence for a systemic vessel involvement
Aims: The decrease in uterine resistance during normal pregnancy is known to be related to invading trophoblast cells which derive from placental tissue. Uterine and peripheral resistance is elevated in preeclampsia. The aim of the present study was to prospectively examine uterine and peripheral resistance in pregnancies complicated by preeclampsia (PE), fetal intrauterine growth restriction (IUGR) and pregnancy induced hypertension (PIH). Methods: Sixty-seven women with normal pregnancies, 17 with PE, 12 with IUGR underwent Doppler sonographic investigation of the uterine and the cubital arteries. The Pulsatility Index (PI) was calculated for each vessel. Statistical analysis was performed and a P-value < 0.05 was considered significant. Results: Patients with preeclampsia and IUGR showed a significant higher resistance at the placental (mean PI 1.267 and 1.063), nonplacental (mean PI 1.631 and 1.124) and cubital artery (mean PI 3,777 and 3.995) compared to the normal pregnancy group (mean PI 0.678; 0.859 and 2.95 respectively). Mean birth weight in the PE group was 1409 g, in the IUGR group 1649 g and 3419 g in the normal pregnancy group. Conclusions: Pregnancies with IUGR are associated with elevated peripheral resistance in the maternal arterial system as seen in pregnancies with preeclampsia. Our findings encourage to further investigate the maternal vascular system in high risk pregnancies
Control of Grapholitha lobarzewskii in the region Bodensee
Im Rahmen eines durch die LVWO Weinsberg durchgefĂĽhrten Ringversuchs konnte
an 8 Standorten mit starkem Vorjahresbefall die Bekämpfung mittels
Pheromonverwirrung ĂĽberprĂĽft werden. Die Untersuchung war aus 2 GrĂĽnden
interessant:
1. Zeigt die Verwirrungsmethode auch bei hohem Ausgangsbefall ausreichend
Wirkung?
2. Ist die Verwirrungsmethode auch auf kleinen Teilflächen sinnvoll einsetzbar
The liquid-glass transition of silica
We studied the liquid-glass transition of by means of replica theory,
utilizing an effective pair potential which was proved to reproduce a few
experimental features of silica. We found a finite critical temperature ,
where the system undergoes a phase transition related to replica symmetry
breaking, in a region where experiments do not show any transition. The
possible sources of this discrepancy are discussed.Comment: 14 pages, 6 postscript figures. Revised version accepted for
pubblication on J.Chem.Phy
Matching with respect to general concept inclusions in the Description Logic EL
Matching concept descriptions against concept patterns was introduced as a new inference task in Description Logics (DLs) almost 20 years ago, motivated by applications in the Classic system. For the DL EL, it was shown in 2000 that the matching problem is NP-complete. It then took almost 10 years before this NP-completeness result could be extended from matching to unification in EL. The next big challenge was then to further extend these results from matching and unification without a TBox to matching and unification w.r.t. a general TBox, i.e., a finite set of general concept inclusions. For unification, we could show some partial results for general TBoxes that satisfy a certain restriction on cyclic dependencies between concepts, but the general case is still open. For matching, we solve the general case in this paper: we show that matching in EL w.r.t. general TBoxes is NP-complete by introducing a goal-oriented matching algorithm that uses non-deterministic rules to transform a given matching problem into a solved form by a polynomial number of rule applications. We also investigate some tractable variants of the matching problem
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