1,256 research outputs found

    Temperature Effects on Development of Three Cereal Aphid Parasitoids (Hymenoptera: Aphidiidae)

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    Temperature is an important climatological variable that influences the biology and ecology of insects. Poor climatic adaptation can limit the effectiveness of parasitic insects in biological control. Two exotic parasites (Syrian Diaeretiella rapae (M\u27Intosh) and Argentinean Aphidius colemani Viereck) imported for biological control of the Russian wheat aphid, Diuraphis noxia (Mordvilko), and one native parasite (Diaeretiella rapae) were reared in growth chambers in three fluctuating temperature regimes with average daily temperatures of 12, 18, and 24Ā°C. Estimates of temperature thresholds for immature development were 3.3, 3.5, and 2.8Ā°C, for Oklahoman D. rapae, Syrian D. rapae, and A. colemani, respectively. Estimates of thermal require- ments for development from egg to adult were 297, 278, and 301 degree-days for the three parasitoids. Dry weights of adults reared in different fluctuating temperature regimes did not differ significantly among sexes, but adults from regimes with low average temperatures of 12 and 18Ā°C had significantly greater weights than those reared in a regime with an average temperature of 24Ā°C. Results suggest that developmental response to temperature will not limit the effectiveness of the exotic parasites in biological control

    Operation of Multiple Reservoir Systems: A Case Study of the Upper Vistula System (An Introduction)

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    Water resource systems have been an important part of resources and environment related research at IIASA since its inception. As demands for water increase relative to supply, the intensity and efficiency of water resources management must be developed further. This in turn requires an increase in the degree of detail and sophistication of the analysis, including economic, social and environmental evaluation of water resources development alternatives aided by application of mathematical modeling techniques, to generate inputs for planning, design, and operational decisions. During the year of 1978 it was decided that parallel to the continuation of demand studies, an attempt would be made to integrate the results of our studies on water demands with water supply considerations. This new task was named "Regional Water Management" (Task 1, Resources and Environment Area). This paper is concerned with operational decision-making in the existing multiple reservoir systems. Following a short description of the case system, three different approaches to optimization of the system's operation are presented. First, the three-step stochastic implicit approach; second, the simulation approach; and third, the approach based on the concepts of hierarchical control systems. Distinction is made between the long-term reservoir operation rules and the short-term operational decisions using the real-time forecasts of reservoir inflows and water demands. The paper is part of a collaborative study on the operation of the Upper Vistula multiple reservoir system in Poland, carried out by the Institute for Meteorology and Water Management, Warsaw, Poland and IIASA

    Multiple Sedimentary Sequences, Bird Tracks and Lagoon Beaches in Last Interglacial Oolites, Boiling Hole, North Eleuthera Island, Bahamas

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    Our review of the last interglacial (Marine Isotope Stage 5e) stratigraphic record from the Boiling Hole exposure in northern Eleuthera Island, Bahamas, revealed the occurrence of two vertically stacked shallowing-upward sequences of oolitic coastal deposits showing beach facies at about 3 and 6 m above mean sea level, respectively. These beach strata dip towards the bank interior and the upper one includes a paleosurface on top of an oolitic grainstone bed with a 2-m-long bird trackway. These fossil beaches correspond to two distinctive sea-level highstands during the last interglacial that could have possibly reached +5 and +8 m above modem datum, respectively, if estimates of regional subsidence are indeed correct. The bird footprints are the first reported occurrence of vertebrate trace fossils from the Bahama Archipelago. The track maker was probably an extant shorebird belonging to the Order Charadriiformes. Track preservation in an oolitic grainstone is remarkable and may be related to an early phase of halite cementation. Finally, the dip of the beach beds indicates that constituent grains were transported onto the island from the bank side by a westerly flux opposite to the modem sediment transport direction in the area

    Geology of New Providence Island, Bahamas: A Field Trip Guide

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    See other Smith authored Field Trip Guides of Gerace Research Centre

    Oxygen isotope analyses of Equus teeth evidences early Eemian and early Weichselian palaeotemperatures at the Middle Palaeolithic site of Neumark-Nord 2, Saxony-Anhalt, Germany

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    We thank Annabell Reiner (MPI-EVA) for technical and practical support with preparation of samples and Bernd Steinhilber for the oxygen isotope measurements of the silver phosphate samples at the Institut fĆ¼r Geowissenschaften (UniversitƤt TĆ¼bingen); Thanks to the Landesamt fĆ¼r Denkmalpflege und ArchƤologie, Sachsen-Anhalt, and Landesmuseum Sachsen-Anhalt in Halle for providing samples; and to Geoff Smith (RGZM Monrepos and MPI-EVA) for comments on earlier versions of this manuscript. Financial support for the Neumark-Nord 2 excavations was provided by the Lausitzer Mitteldeutsche Braunkohlengesellschaft mbH, the Landesamt fĆ¼r Denkmalpflege und ArchƤologie Sachsen-Anhalt (Harald Meller, Susanne Friederich), the Rƶmisch-Germanisches Zentralmuseum Mainz, the Leids Universiteits Fonds ā€œCampagne voor Leidenā€ program and the NetherlandsOrganization for Scientific Research (N.W.O.). The isotope research was funded by the Max Planck Institute and a Deutscher Akademischer Austausch Dienst Junior Research Grant to KB (ref: A0970923). Thanks also to the University of Aberdeen, and The Leverhulme Trust (RPG-2017-410) for financial and professional support during this project and preparation of the manuscript. TT acknowledges funding by the German National Science foundation in the framework of the Emmy Noether Program (DFG grant TU 148/2-1 ā€œBone Geochemistryā€).Peer reviewedPostprin

    A Logical Verification Methodology for Service-Oriented Computing

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    We introduce a logical verification methodology for checking behavioural properties of service-oriented computing systems. Service properties are described by means of SocL, a branching-time temporal logic that we have specifically designed to express in an effective way distinctive aspects of services, such as, e.g., acceptance of a request, provision of a response, and correlation among service requests and responses. Our approach allows service properties to be expressed in such a way that they can be independent of service domains and specifications. We show an instantiation of our general methodology that uses the formal language COWS to conveniently specify services and the expressly developed software tool CMC to assist the user in the task of verifying SocL formulae over service specifications. We demonstrate feasibility and effectiveness of our methodology by means of the specification and the analysis of a case study in the automotive domain

    Theory of the first-order isostructural valence phase transitions in mixed valence compounds YbIn_{x}Ag_{1-x}Cu_{4}

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    For describing the first-order isostructural valence phase transition in mixed valence compounds we develop a new approach based on the lattice Anderson model. We take into account the Coulomb interaction between localized f and conduction band electrons and two mechanisms of electron-lattice coupling. One is related to the volume dependence of the hybridization. The other is related to local deformations produced by f- shell size fluctuations accompanying valence fluctuations. The large f -state degeneracy allows us to use the 1/N expansion method. Within the model we develop a mean-field theory for the first-order valence phase transition in YbInCu_{4}. It is shown that the Coulomb interaction enhances the exchange interaction between f and conduction band electron spins and is the driving force of the phase transition. A comparison between the theoretical calculations and experimental measurements of the valence change, susceptibility, specific heat, entropy, elastic constants and volume change in YbInCu_{4} and YbAgCu_{4} are presented, and a good quantitative agreement is found. On the basis of the model we describe the evolution from the first-order valence phase transition to the continuous transition into the heavy-fermion ground state in the series of compounds YbIn_{1-x}Ag_{x}Cu_{4}. The effect of pressure on physical properties of YbInCu_{4} is studied and the H-T phase diagram is found.Comment: 17 pages RevTeX, 9 Postscript figures, to be submitted to Phys.Rev.
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