50 research outputs found
Weihnachtskaktus - Schlumbergera (Cactaceae)
PflanzenportrÀt
Urban soils in the Ruhr Area
Die rĂ€umliche Konzentration menschlichen Wirkens im stĂ€dtischen Raum fĂŒhrt seit jeher zu VerĂ€nderungen der
Böden. Im Ruhrgebiet bewirkte vor allem die montan-industrielle Vergangenheit tiefgreifende VerÀnderungen,
weshalb die heutigen Böden sich z. T. stark von den ursprĂŒnglichen natĂŒrlichen BodenverhĂ€ltnissen unterscheiden.
Einige der neu entstandenen Böden finden in Europa keine natĂŒrlichen Ăquivalente und bilden einzigartige Standorte. Auch wenn das eigentliche Merkmal stĂ€dtischer Böden ihre gegenĂŒber den natĂŒrlichen VerhĂ€ltnissen erhöhte DiversitĂ€t ist, lassen sich hĂ€ufig anzutreffende Charakteristika wie erhöhte Skelettgehalte, pH-Werte und
Schadstoffgehalte sowie Verdichtungen und Versiegelungen feststellen. Nicht zuletzt aufgrund der vielfÀltigen Einflussfaktoren auf die Bodenentwicklung hat sich im deutschen Sprachgebrauch nur teilweise eine eindeutige und einheitliche (verbindliche) Klassifikation durchgesetzt, sodass mehrere AnsÀtze und Nomenklaturen existieren.
Zu den ruhrgebietstypischen Böden zÀhlen etwa die Böden auf Bergematerial des Steinkohlenbergbaus, die
Böden auf Hochofenschlacken oder die Böden auf brachliegenden Bahngleisen. Sie bilden z. T. extreme
Pflanzenstandorte und unterscheiden sich stark voneinander, wie es beispielsweise der Gegensatz zwischen dem sehr sauren Bergematerial und den stark alkalischen Schlacken verdeutlicht. Diese DiversitÀt wirkt sich auch
entsprechend auf die Pflanzenartenvielfalt im urbanen Raum aus. Zudem speichern Stadtböden Informationen zu
vergangenen UmweltzustÀnden und zur Entwicklung der StÀdte, die von archÀologischer und siedlungsgeschichtlicher
Bedeutung sind.The urban-industrial history of the Ruhr Area caused significant alteration of soils. Therefore, the characteristics of urban soils differ in many ways from the natural soils. This paper provides information about general soil properties in the urban environment. Soil development and soil characteristics on typical sites and substrates
frequently found in the Ruhr Area are described in more detail. Urban-specific soil types and their German
nomenclature and classification are summarized. Furthermore, the role of urban soils as archives of settlement
development and the relationships between soil and vegetation are examined
An Ins(1,4,5)P3 receptor in Paramecium is associated with the osmoregulatory system
In the ciliate Paramecium, a variety of well characterized processes are regulated by Ca2+, e.g. exocytosis, endocytosis and ciliary beat. Therefore, among protozoa, Paramecium is considered a model organism for Ca2+ signaling, although the molecular identity of the channels responsible for the Ca2+ signals remains largely unknown. We have cloned - for the first time in a protozoan - the full sequence of the gene encoding a putative inositol (1,4,5)-trisphosphate (Ins(1,4,5)P3) receptor from Paramecium tetraurelia cells showing molecular characteristics of higher eukaryotic cells. The homologously expressed Ins(1,4,5)P3-binding domain binds [3H]Ins(1,4,5)P3, whereas antibodies unexpectedly localize this protein to the osmoregulatory system. The level of Ins(1,4,5)P3-receptor expression was reduced, as shown on a transcriptional level and by immuno-staining, by decreasing the concentration of extracellular Ca2+ (Paramecium cells rapidly adjust their Ca2+ level to that in the outside medium). Fluorochromes reveal spontaneous fluctuations in cytosolic Ca2+ levels along the osmoregulatory system and these signals change upon activation of caged Ins(1,4,5)P3. Considering the ongoing expulsion of substantial amounts of Ca2+ by the osmoregulatory system, we propose here that Ins(1,4,5)P3 receptors serve a new function, i.e. a latent, graded reflux of Ca2+ to fine-tune [Ca2+] homeostasis
Experimental Verification and Analysis of Dynamic Loop Scheduling in Scientific Applications
Scientific applications are often irregular and characterized by large computationally-intensive parallel loops. Dynamic loop scheduling (DLS) techniques improve the performance of computationally-intensive scientific applications via load balancing of their execution on high-performance computing (HPC) systems. Identifying the most suitable choices of data distribution strategies, system sizes, and DLS techniques which improve the performance of a given application, requires intensive assessment and a large number of exploratory native experiments (using real applications on real systems), which may not always be feasible or practical due to associated time and costs. In such cases, simulative experiments are more appropriate for studying the performance of applications. This motivates the question of âHow realistic are the simulations of executions of scientific applications using DLS on HPC platforms?â In the present work, a methodology is devised to answer this question. It involves the experimental verification and analysis of the performance of DLS in scientific applications. The proposed methodology is employed for a computer vision application executing using four DLS techniques on two different HPC platforms, both via native and simulative experiments. The evaluation and analysis of the native and simulative results indicate that the accuracy of the simulative experiments is strongly influenced by the approach used to extract the computational effort of the application (FLOP- or time-based), the choice of application model representation into simulation (data or task parallel), and the available HPC subsystem models in the simulator (multi-core CPUs, memory hierarchy, and network topology). The minimum and the maximum percent errors achieved between the native and the simulative experiments are 0.95% and 8.03%, respectively
An Approach for Realistically Simulating the Performance of Scientific Applications on High Performance Computing Systems
Scientific applications often contain large, computationally-intensive, and
irregular parallel loops or tasks that exhibit stochastic characteristics.
Applications may suffer from load imbalance during their execution on
high-performance computing (HPC) systems due to such characteristics. Dynamic
loop self-scheduling (DLS) techniques are instrumental in improving the
performance of scientific applications on HPC systems via load balancing.
Selecting a DLS technique that results in the best performance for different
problems and system sizes requires a large number of exploratory experiments. A
theoretical model that can be used to predict the scheduling technique that
yields the best performance for a given problem and system has not yet been
identified. Therefore, simulation is the most appropriate approach for
conducting such exploratory experiments with reasonable costs. This work
devises an approach to realistically simulate computationally-intensive
scientific applications that employ DLS and execute on HPC systems. Several
approaches to represent the application tasks (or loop iterations) are compared
to establish their influence on the simulative application performance. A novel
simulation strategy is introduced, which transforms a native application code
into a simulative code. The native and simulative performance of two
computationally-intensive scientific applications are compared to evaluate the
realism of the proposed simulation approach. The comparison of the performance
characteristics extracted from the native and simulative performance shows that
the proposed simulation approach fully captured most of the performance
characteristics of interest. This work shows and establishes the importance of
simulations that realistically predict the performance of DLS techniques for
different applications and system configurations
Experimental Verification and Analysis of Dynamic Loop Scheduling in Scientific Applications
Scientific applications are often irregular and characterized by large
computationally-intensive parallel loops. Dynamic loop scheduling (DLS)
techniques improve the performance of computationally-intensive scientific
applications via load balancing of their execution on high-performance
computing (HPC) systems. Identifying the most suitable choices of data
distribution strategies, system sizes, and DLS techniques which improve the
performance of a given application, requires intensive assessment and a large
number of exploratory native experiments (using real applications on real
systems), which may not always be feasible or practical due to associated time
and costs. In such cases, simulative experiments are more appropriate for
studying the performance of applications. This motivates the question of How
realistic are the simulations of executions of scientific applications using
DLS on HPC platforms? In the present work, a methodology is devised to answer
this question. It involves the experimental verification and analysis of the
performance of DLS in scientific applications. The proposed methodology is
employed for a computer vision application executing using four DLS techniques
on two different HPC plat- forms, both via native and simulative experiments.
The evaluation and analysis of the native and simulative results indicate that
the accuracy of the simulative experiments is strongly influenced by the
approach used to extract the computational effort of the application (FLOP- or
time-based), the choice of application model representation into simulation
(data or task parallel), and the available HPC subsystem models in the
simulator (multi-core CPUs, memory hierarchy, and network topology). The
minimum and the maximum percent errors achieved between the native and the
simulative experiments are 0.95% and 8.03%, respectively
The 24/7 approach to promoting optimal welfare for captive wild animals
We have an ethical responsibility to provide captive animals with environments that allow them to experience good welfare. Husbandry activities are often scheduled for the convenience of care staff working within the constraints of the facility, rather than considering the biological and psychological requirements of the animals themselves. The animal welfare 24/7 across the lifespan concept provides a holistic framework to map features of the animalâs life cycle, taking into account their natural history, in relation to variations in the captive environment, across day and night, weekdays, weekends, and seasons. In order for animals to have the opportunity to thrive, we argue the need to consider their lifetime experience, integrated into the environments we provide, and with their perspective in mind. Here, we propose a welfare assessment tool based upon 14 criteria, to allow care staff to determine if their animalsâ welfare needs are met. We conclude that animal habitat management will be enhanced with the use of integrated technologies that provide the animals with more opportunities to engineer their own environments, providing them with complexity, choice and control
Exkursion: Hattingen-Niederbonsfeld, geologisch-geomorphologische Exkursion im Ruhrtal am Isenberg
Am steilen Prallhang der Ruhr zwischen Hattingen und Niederwenigern ist die vermutlich lĂ€ngste zusammenhĂ€ngende Gesteinsfolge des Ruhrgebiets aufgeschlossen, deren sĂŒdlicher Abschnitt im Rahmen der Exkursion nĂ€her betrachtet wurde. Im Mittelpunkt standen die besonders deutlich ausgeprĂ€gten ZusammenhĂ€nge zwischen der inneren geologischen Struktur des Steinkohlengebirges und dem heutigen OberflĂ€chenrelief mit seinen markanten BergrĂŒcken (Eggen). Die Eggen sind sĂŒdlich des Ruhrtals zwischen Kettwig und Witten derart bestimmend fĂŒr das Landschaftsbild, dass die entsprechenden Gebiete im Rahmen der naturrĂ€umlichen Gliederung des Ruhrgebiets durch VON KĂRTEN (1970) als Ruhr- Eggenland und MĂ€rkisches Eggenland bezeichnet werden