166 research outputs found

    Honey bee foraging distance depends on month and forage type

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    To investigate the distances at which honey bee foragers collect nectar and pollen, we analysed 5,484 decoded waggle dances made to natural forage sites to determine monthly foraging distance for each forage type. Firstly, we found significantly fewer overall dances made for pollen (16.8 %) than for non-pollen, presumably nectar (83.2 %; P < 2.2 × 10−23). When we analysed distance against month and forage type, there was a significant interaction between the two factors, which demonstrates that in some months, one forage type is collected at farther distances, but this would reverse in other months. Overall, these data suggest that distance, as a proxy for forage availability, is not significantly and consistently driven by need for one type of forage over the other

    First-level trigger systems for LHC experiments

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    We propose to carry out a broad-based programme of R&D on level-1 trigger systems for LHC experiments. We will consider the overall level-1 which coordinates different subtriggers and which interacts with the front end electronics and with the level-2 system. Careful attention will be paid to systems aspects and problems of synchronization within the pipelined processor system. Trigger algorithms for selecting events with high-pt electrons, photons, muons, jets and large missing Et will be evaluated by physics simulation studies. We will study possible implementations of such trigger algorithms in fast electronics by making conceptual design studies and using behavioural simulation models. For critical areas more detailed design studies will be made, and prototypes of some key elements will be constructed and tested. The proposed R&D project builds on existing studies and will complement other R&D projects already funded by the DRDC

    Phospholipase D signaling: orchestration by PIP2 and small GTPases

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    Hydrolysis of phosphatidylcholine by phospholipase D (PLD) leads to the generation of the versatile lipid second messenger, phosphatidic acid (PA), which is involved in fundamental cellular processes, including membrane trafficking, actin cytoskeleton remodeling, cell proliferation and cell survival. PLD activity can be dramatically stimulated by a large number of cell surface receptors and is elaborately regulated by intracellular factors, including protein kinase C isoforms, small GTPases of the ARF, Rho and Ras families and, particularly, by the phosphoinositide, phosphatidylinositol 4,5-bisphosphate (PIP2). PIP2 is well known as substrate for the generation of second messengers by phospholipase C, but is now also understood to recruit and/or activate a variety of actin regulatory proteins, ion channels and other signaling proteins, including PLD, by direct interaction. The synthesis of PIP2 by phosphoinositide 5-kinase (PIP5K) isoforms is tightly regulated by small GTPases and, interestingly, by PA as well, and the concerted formation of PIP2 and PA has been shown to mediate receptor-regulated cellular events. This review highlights the regulation of PLD by membrane receptors, and describes how the close encounter of PLD and PIP5K isoforms with small GTPases permits the execution of specific cellular functions

    DELPHI Drawing Database

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    J/psi production properties with UA1

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    New evidence for the age of the Athol Formation (Middle Jurassic : Bajocian) in the Tusk-1 and Tusk-2 wells, offshore Carnarvon Basin, Western Australia

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    The co-occurrence of ammonites with palynomorphs in the Athol Formation of the Tusk-1 and Tusk-2 wells drilled in the offshore Carnarvon Basin, Western Australia confirms the Early Bajocian (Middle Jurassic) age of the Dissiliodinium caddaense dinoflagellate cyst Oppel Zone. The macrofaunas refine this Early Bajocian age to the early Laeviuscula Chronozone. A belemnite from the Tusk-1 well has a strontium isotope (87Sr/86Sr) ratio consistent with the biostratigraphical age. All the identifiable ammonites belong to Pseudotoites robiginosus (Crick). Pseudotoites is prominent in the Early Bajocian of the Indo-Pacific Realm, being known mainly from onshore Western Australia and the Southern Andes, together with rare occurrences in Irian Jaya (west New Guinea); somewhat surprisingly, it is also rarely present in southern Alaska. The palynofloras studied from the Tusk-1 and Tusk-2 wells contain abundant specimens of the marine dinoflagellate cyst Dissiliodinium caddaense, and are assigned to the Dissiliodinium caddaense Oppel Zone. The Athol Formation is a correlative of the Newmarracarra Limestone of the onshore Perth Basin, Western Australia; the distribution of both these units indicates a marine transgression onto the Australian block during the Early Bajocian
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