Collision of Polymers in a Vacuum

In a number of experimental situations, single polymer molecules can be suspended in a vacuum. Here collisions between such molecules are considered. The limit of high collision velocity is investigated numerically for a variety of conditions. The distribution of contact times, scattering angles, and final velocities are analyzed. In this limit, self avoiding chains are found to become highly stretched as they collide with each other, and have a distribution of scattering times that depends on the scattering angle. The velocity of the molecules after the collisions is similar to predictions of a model assuming thermal equilibration of molecules during the collision. The most important difference is a significant subset of molecules that inelastically scatter but do not substantially change direction.Comment: 7 pages, 6 figure

Culturally responsive classrooms through art integration

Integrating arts into teaching and learning can result in more engaging classrooms for students of all backgrounds. Addressing content through drawing, painting, music, drama, sculpture, and manipulatives results in motivating lessons that reach diverse learners by means of multiple pathways. Benefits of incorporating the arts include not only academic achievement (Ruppert, 2006; Rabkin & Redmond, 2006), but also increased cultural understandings, better self-esteem, and a healthier cultural identity (Purnell, et al., 2007; Graham, 2009). Sample lessons with detailed explanations from an elementary classroom are highlighted to demonstrate how forms of linguistic and nonlinguistic artistic expression benefit all children in their development

The assessment of naturalness and its role for nature conservation and forestry in Europe

Naturalness is one of the most important criteria in nature conservation. This paper examines the fundamental concepts underlying the definition and assessment of naturalness. Its role in nature conservation and forest management under conditions of global change is also discussed. The degree of naturalness may be defined in ordinal classes. The “static” concept of the potential natural vegetation (pnV), developed in the 1950ies, is mostly used as the reference state. In other cases, its reversed concept, the hemeroby (degree of articifiality) is assessed, based on the intensity and frequency of human impacts. Since the 1970ies, more attention has been given to natural dynamics than in earlier approaches, e.g. in forest succession models. At the end of the 1980ies, the previous importance was increasingly stressed of natural browsing by large herbivores and the role of predators. These large herbivors are extinct today in most cultural European landscapes. It is assumed, that they open up the canopy, and create park-like forest structures which contain a diversity of habitats for other types of organism (birds, insects). Changed and permanently changing environments and altering patterns of competition between species continue to modify natural processes today. Some of the more conspicuous effects are the extinction of native species and immigration of species to new regions. Long-lived ecosystems like forests are however not able to adapt quickly to such changes and may be unable to find a new balance with the environment. Today, such changes occur very rapidly, and are reducing the original naturalness of ecosystems. Because of this, the criterion “naturalness” must be downweighted. Conversely, more importance should be attached to other criteria: particularly originality (= original naturalness) and restorability. Forestry is contributing to this accelerated change of biocoenoses by increasing disturbances and introducing exotic tree species. Naturalisation of some exotic tree species modifies the natural processes and creates a “new allochthonous naturalness”. Because of this, forest planning should try to preserve or restore stands with attributes of the “original forest”. Exotic species should not be planted, or only in a very restricted way.Naturnähe ist eines des wichtigsten Bewertungskritierien im Naturschutz. Die vorliegende Arbeit untersucht die den gängigen Naturnähe-Konzepten zugrundeliegenden Definitionen und Bewertungsmaßstäbe. Auch wird die Rolle von Naturnähe für Naturschutz und Waldbewirtschaftung im „Globalen Landschaftswandel“ diskutiert. Die Einteilung von Naturnähe erfolgt in graduellen Abstufungen. Zumeist wird dazu das “statische” in den 1950 er Jahren entwickelte Konzept der Potenziellen natürlichen Vegetation Vegetation (pnV) verwendet. In anderen Fällen wird die zur Naturähe gegenläufige Hemerobie (Grad des Nutzungseinflusses) herangezogen. Seit den 1970er Jahren wurden verstärkt Aspekte der natürlichen Dyanmik berücksichtigt, z.B. sogenannte „Phasenmodelle“. Ende der 1980er Jahre wurde die ehemalige Bedeutung der Megafauna (große Pflanzenfresser und Prädatoren) hervorgehoben, die heute in den europäischen Kulturlandschaften weitgehend ausgestorben sind. Es wird vermutet, dass Megaherbivoren einst in der Lage waren, den Wald aufzulichten und teilweise parkartige Strukturen mit einer großen Habitatvielfalt für andere Tierartengruppen (Vögel, Insekten) zu schaffen. Veränderte und sich permanent ändernde Umweltbedingungen und sich wandelnde Konkurrenzmuster zwischen den Arten führen auch heute zu sich laufend ändernden Naturprozessen. Einige der auffälligsten Effekte sind das Aussterben heimischer Arten und die Einwanderung von „fremden“ Arten in neue Regionen. Langlebige Ökosysteme wie die Wälder sind nicht in der Lage, rasch ein neues Gleichgewicht mit den Umweltbedingungen zu finden, ihre Umstellung dauert viele Jahrzehnte. Heute finden Veränderungen von Standortsbedingungen sowie die Einwanderung von Tier- und Pflanzenarten sehr rasch statt. Diese Prozesse reduzieren die frühere Naturnähe („Ursprünglichkeit“) der Ökosysteme. Deshalb ist bei naturschutzfachlichen Bewertungen das Kriterium „Naturnähe“ aus heutiger Sicht tendenziell geringer zu wichten. Umgekehrt sollte anderen Aspekten größere Bedeutung beigemessen werden, insbesondere der Ursprünglichkeit (bzw. angestammten Naturnähe) und der Wiederherstellbarkeit. Die Forstwirtschaft trägt zu einem beschleunigten Wandel der Lebensgemeinschaften bei durch zunehmende Eingriffe (Häufigkeit, Intensität) und Einbringen von Gastbaumarten. Die Einbürgerung einiger exotischer Baumarten verändert die natürlichen Prozesse und kreiert eine “neue allochthone Naturnähe”. Deshalb sollte die Forstplanung versuchen, „angestammt naturnahe“ Bestände zu schützen oder wiederherstellen. Exotische Arten sollten nur in einem sehr begrenzten Umfang angepflanzt werden

Global analysis of threat status reveals higher extinction risk in tropical than in temperate bird sister species

Given increasing pressures upon biodiversity, identification of species’ traits related to elevated extinction risk is useful for more efficient allocation of limited resources for nature conservation. Despite its need, such a global analysis was lacking in the case of birds. Therefore, we performed this exercise for avian sister species using  information about their global extinction risk from IUCN Red List. We focused on 113 pairs of sister species, each containing a threatened and an unthreatened species to factor out the effects of common evolutionary history on the revealed relationship. We collected data on five traits with expected relationships to species’ extinction risk based on previous studies performed at regional or national levels: breeding habitat (recognizing forest, grassland, wetland and oceanic species), latitudinal range position (temperate and tropics species), migration strategy (migratory and resident species), diet (carnivorous, insectivorous, herbivorous and omnivorous species)  and body mass. We related the extinction risk using IUCN threat level categories to species’ traits using generalised linear mixed effects models expecting lower risk for forest, temperate, omnivorous and smaller-bodied species. Our expectation was confirmed only in the case of latitudinal range position, as we revealed higher threat level for tropical than for temperate species. This relationship was robust to different methods of threat level expression and cannot be explained by a simple association of high bird species richness with the tropical zone. Instead, it seems that tropical species are more threatened because of their intrinsic characteristics such as slow life histories, adaptations to stable environments and small geographic ranges. These characteristics are obviously disadvantageous in conditions of current human-induced environmental perturbations. Moreover, given the absence of habitat effects, our study indicates that such perturbations act across different tropical environments. Therefore, disproportionally higher conservation effort in the tropics compared to the temperate zone is urgently needed

Parallel image compression

A parallel compression algorithm for the 16,384 processor MPP machine was developed. The serial version of the algorithm can be viewed as a combination of on-line dynamic lossless test compression techniques (which employ simple learning strategies) and vector quantization. These concepts are described. How these concepts are combined to form a new strategy for performing dynamic on-line lossy compression is discussed. Finally, the implementation of this algorithm in a massively parallel fashion on the MPP is discussed

Parallel Batch-Dynamic Graph Connectivity

In this paper, we study batch parallel algorithms for the dynamic connectivity problem, a fundamental problem that has received considerable attention in the sequential setting. The most well known sequential algorithm for dynamic connectivity is the elegant level-set algorithm of Holm, de Lichtenberg and Thorup (HDT), which achieves $O(\log^2 n)$ amortized time per edge insertion or deletion, and $O(\log n / \log\log n)$ time per query. We design a parallel batch-dynamic connectivity algorithm that is work-efficient with respect to the HDT algorithm for small batch sizes, and is asymptotically faster when the average batch size is sufficiently large. Given a sequence of batched updates, where $\Delta$ is the average batch size of all deletions, our algorithm achieves $O(\log n \log(1 + n / \Delta))$ expected amortized work per edge insertion and deletion and $O(\log^3 n)$ depth w.h.p. Our algorithm answers a batch of $k$ connectivity queries in $O(k \log(1 + n/k))$ expected work and $O(\log n)$ depth w.h.p. To the best of our knowledge, our algorithm is the first parallel batch-dynamic algorithm for connectivity.Comment: This is the full version of the paper appearing in the ACM Symposium on Parallelism in Algorithms and Architectures (SPAA), 201

Total Costs and Budgetary Effects of Adaptation to Climate Change: An Assessment for the European Union

Adaptation to climate change is gaining increasing relevance in the public debate of climate policy. However, detailed and regionalised cost estimates as a basis for cost-benefit-analyses are rare. We compose available cost estimates for adaptation in Europe, and in particular Germany, Finland and Italy. Furthermore, a systematic overview on fiscal aspects of adaptation is provided, with focus on budgetary effects of adaptation in the different impact sectors. Combining cost estimates, considerations on fiscal aspects and governmental interventions in adaptation processes, we present data-based guesses of public adaptation costs in the EU, divided by impact sectors. The findings show an expectedly large public burden in the adaptation of transport infrastructure and coastal protection, while high adaptation costs in the agriculture sector are predominantly private. The change in energy demand may well lead to a significant decrease in public expenditure. Considering the regional heterogeneity of adaptation measures and the high uncertainty of quantitative adaptation analyses, further research in the form of bottom-up-studies is needed.adaptation, climate change, adaptation costs, fiscal effects, governmental intervention