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  • 1
    ISSN: 1432-0452
    Keywords: Key words: Distributed systems – Event abstraction – Causality – Precedence relation – Partial order – Vector time – Logical time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract. An important problem in analyzing distributed computations is the amount of information. In event-based models, even for simple applications, the number of events is large and the causal structure is complex. Event abstraction can be used to reduce the apparent complexity of a distributed computation. This paper discusses one important aspect of event abstraction: causality among abstract events. Following Lamport [24], two causality relations are defined on abstract events, called weak and strong precedence. A general theoretical framework based on logical vector time is developed in which several meaningful timestamps for abstract events are derived. These timestamps can be used to efficiently determine causal relationships between arbitrary abstract events. The class of convex abstract events is identified as a subclass of abstract events that is general enough to be widely applicable and restricted enough to simplify timestamping schemes used for characterizing weak precedence. We explain why such a simplification seems not possible for strong precedence.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-136X
    Keywords: Key words Milk composition ; Lactation ; Calcium ; Bats ; Phyllostomatidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Growth rates of mammalian young are closely linked to the ability of the mother to provide nutrients; thus, milk composition and yield provide a direct measure of maternal investment during lactation in many mammals. We studied changes in milk composition and output throughout lactation in a free-ranging population of the omnivorous bat, Phyllostomus hastatus. Fat and dry matter of milk increased from 9 to 21% and from 21 to 35% of wet mass, respectively, throughout lactation. Energy increased from 6 to 9 kJ · g−1 wet mass, primarily due to the increase in fat concentration. Total sugar levels decreased slightly but non-significantly. Mean sugar level was 4.0% of wet mass. Protein concentration increased from 6 to 11% of wet mass at peak lactation and then decreased as pups approached weaning age. Total milk energy output until pups began to forage was 3609 kJ. Milk levels of Mg, Fe, Ca, K, and Na averaged 0.55 ± 0.26, 0.23 ± 0.2, 8.75 ± 4.17, 5.42 ± 2.11, and 9.87 ± 4.3 mg · g−1 dry matter, respectively. Of the minerals studied, calcium appears to be most limiting in this species. The high degree of variability in foraging time, milk composition and milk yield between individuals at the same stage of lactation could potentially yield high variance in reproductive success among females of this polygynous species.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 367 (1994), S. 691-692 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - Although male lactation is physiologically possible1, it is isolated and rare. It has been observed in domesticated mammals2'3 and in humans4'5, but it has not been reported in wild, free-ranging species. Here we report lactation by males in a population of Dayak fruit bats, Dyacopterus ...
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Automated software engineering 4 (1997), S. 179-197 
    ISSN: 1573-7535
    Keywords: Program understanding ; distributed debugging ; visualization ; Hermes ; program behavior ; abstraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Due to the complexity of distributed applications, understanding their behaviour is a challenging task. To remedy this problem, graphical visualizations of distributed executions in the form of process-time diagrams are frequently employed. However, such process-time diagrams do not scale for long-running and complex distributed applications. To reduce the display complexity, abstract graphical views of an execution are frequently suggested. One commonly used abstraction is to group primitive events into abstract events. This paper discusses some of the problems encountered when analyzing executions at abstract levels and introduces the concept of convex abstract events. Such abstract events can be used to reason about executions at higher levels, facilitating program development, debugging, and maintenance. We discuss some fundamental aspects, such as the precedence relation and its efficient detection, for abstract events. The paper also presents a graphical representation for convex abstract events which can easily be included in process-time diagrams. Poet, our visualization tool, was enhanced with a facility to display abstract events. Using a non-trivial distributed application, examples of the resulting abstract execution visualizations are discussed.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cluster computing 3 (2000), S. 231-243 
    ISSN: 1573-7543
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Event visualization tools are commonly used to facilitate the debugging of parallel or distributed applications, but they are insufficient for full debugging purposes. The need for traditional debugging operations, such as single stepping, is often overlooked in these tools. When integrating such operations, the issue of concurrency needs to be addressed. This paper justifies and describes three single-stepping operations that we found suitable for partially-ordered executions: global-step, step-over and step-in. The description of these operations is based on a sound theoretical framework. This framework can serve as a basis to extend the operations to deal with specific properties of event visualization tools. For example, abstraction techniques are often used to reduce the overwhelming amount of detail presented to the user when visualizing non-trivial executions. These abstraction operations introduce additional problems for single stepping. The paper discusses the problems induced by two different abstraction operations in the context of a specific event visualization tool, Poet, and describes how the single-stepping operations are adapted to deal with these problems.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 7
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Variation in depth of the mixed surface layer of temperate lakes should affect phytoplankton dynamics because, with increasing mixing depth, average light intensity in and specific sedimentation losses out of the mixed layer both decrease.2. Our aim was to test a recent dynamic model which relates phytoplankton biomass and the availability of production-limiting resources (light and dissolved mineral nutrients) to mixing depth and nutrient supply from external sources.3. During summer stratification we sampled the mixed layers of 30 dimictic, phosphorus-limited, oligo- to mesotrophic, mostly non-humic lakes north of the Alps.4. The results agree well qualitatively with model expectations. Algal concentration in the mixed layer was negatively related to mixing depth or its surrogate log-transformed lake area. Light intensity at the bottom of the mixed layer decreased whereas the concentration of available, inorganic phosphorus increased with increasing mixing depth. Across all depths, higher total phosphorus content was accompanied by higher phytoplankton biomass, lower light availability, and higher inorganic phosphorus concentration.5. Our data match the predicted shift with increasing mixing depth from predominantly nutrient limitation towards increased light limitation of algal biomass.
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  • 8
    ISSN: 1432-1351
    Keywords: Chiroptera ; Muscle development ; Ontogeny of flight ; Postnatal growth ; Muscle histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Postnatal changes in wing morphology, flight ability, muscle morphology, and histochemistry were investigated in the little brown bat, Myotis lucifugus. The pectoralis major, acromiodeltoideus, and quadriceps femoris muscles were examined using stains for myofibrillar ATPase, succinate dehydrogenase (SDH), and mitochondrial α-glycerophosphate dehydrogenase (α-GPDH) enzyme reactions. Bats first exhibited spontaneous, drop-evoked flapping behavior at 10 days, short horizontal flight at 17 days, and sustained flight at 24 days of age. Wing loading decreased and aspect ratio increased during postnatal development, each reaching adult range before the onset of sustained flight. Histochemically, fibers from the three muscles were undifferentiated at birth and had lower oxidative and glycolytic capacities compared to other age groups. Cross-sectional areas of fibers from the pectoralis and acromiodeltoideus muscles increased significantly at an age when dropevoked flapping behavior was first observed, suggesting that the neuromuscular mechanism controlling flapping did not develop until this time. Throughout the postnatal growth period, pectoralis and acromiodeltoideus muscle mass and fiber cross-sectional area increased significantly. By day 17 the pectoralis muscle had become differentiated in glycolytic capacity, as indicated by the mosaic staining pattern for α-GPDH. By contrast, the quadriceps fibers were relatively large at birth and slowly increased in size during the postnatal period. Fiber differentiation was evident at the time young bats began to fly, as indicated by a mosaic pattern of staining for myosin ATPase. These results indicate that flight muscles (pectoralis and acromiodeltoideus) are less well developed at birth and undergo rapid development just before the onset of flight. By contrast the quadriceps femoris muscle, which is required for postural control, is more developed at birth than the flight muscles and grows more slowly during subsequent development.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0170-2041
    Keywords: γ-Lactones ; Radical additions ; Felkin-Anh model ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Radikaladditionen im wäßrigen Medium: Eine direkte Synthese von 5-allylsubstituierten γ-Lactonen aus Allylbromiden/Zink und γ-Oxo-carbonsäureesternNach einer von Luche publizierten Methode werden die 5-allyl-substituierten γ-Lactone 2a-2d in guten Ausbeuten aus den γ-Oxocarbonsäureestern 1a-1c und Allylbromiden/Zinkstaub im wäßrigen Medium hergestellt. Die Diastereoselektivität dieser Allylierungsreaktion wird mit der durch Lewis-Säure-induzierten Allyltrimethylsilan-Addition an chirale Aldehyde verglichen.
    Notes: Following a procedure published by Luche, 5-allyl-substituted γ-lactones 2a-2d are prepared in good yield from methyl γ-oxocarboxylates 1a-1c and allyl bromides/zinc dust in aqueous medium. The diastereoselectivity of this allylation reaction is compared to that of Lewis acid promoted additions of allyltrimethylsilane to chiral aldehydes.
    Additional Material: 4 Tab.
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  • 10
    ISSN: 0197-8462
    Keywords: Coturnix quail ; hatchability ; growth ; microwaves (2.45 GHz, CW) ; solar power ; satellite ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Fertile eggs of the Coturnix quail were exposed twice a day for 30 min to 2.45-GHz continuous wave radiation at power densities of 25 or 50 mW cm-2 throughout the 17-day incubation period. Other eggs were exposed to 20°C or 24°C temperatures twice daily. Repeated exposures to 20°C, 24°C, or 25 mW cm-2 did not reduce hatchability. Irradiation at 50 mW cm-2 lowered hatchability, probably as a result of high egg temperatures. Hatchlings that had been irradiated by microwaves as embryos had normal growth rates and no obvious developmental abnormalities.
    Additional Material: 4 Ill.
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