181 research outputs found

    Biogeography of key mesozooplankton species in the North Atlantic and egg production of Calanus finmarchicus

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    Here we present a new, pan-North-Atlantic compilation of data on key mesozooplankton species, including the most important copepod, Calanus finmarchicus. Distributional data of eight representative zooplankton taxa, from recent (2000–2009) Continuous Plankton Recorder data, are presented, along with basin-scale data of the phytoplankton colour index. Then we present a compilation of data on C. finmarchicus, including observations of abundance, demography, egg production and female size, with accompanying data on temperature and chlorophyll. This is a contribution by Canadian, European and US scientists and their institutions: http://doi.pangaea.de/10.1594/PANGAEA.820732, http://doi.pangaea.de/10.1594/PANGAEA.824423, http://doi.pangaea.de/10.1594/PANGAEA.828393 (please also see Melle et al., 2013; Castellani and Licandro, 2013; Jónasdóttir et al., 2014)

    Prey detection and prey capture in copepod nauplii

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    Copepod nauplii are either ambush feeders that feed on motile prey or they produce a feeding current that entrains prey cells. It is unclear how ambush and feeding-current feeding nauplii perceive and capture prey. Attack jumps in ambush feeding nauplii should not be feasible at low Reynolds numbers due to the thick viscous boundary layer surrounding the attacking nauplius. We use high-speed video to describe the detection and capture of phytoplankton prey by the nauplii of two ambush feeding species (Acartia tonsa and Oithona davisae) and by the nauplii of one feeding-current feeding species (Temora longicornis). We demonstrate that the ambush feeders both detect motile prey remotely. Prey detection elicits an attack jump, but the jump is not directly towards the prey, such as has been described for adult copepods. Rather, the nauplius jumps past the prey and sets up an intermittent feeding current that pulls in the prey from behind towards the mouth. The feeding-current feeding nauplius detects prey arriving in the feeding current but only when the prey is intercepted by the setae on the feeding appendages. This elicits an altered motion pattern of the feeding appendages that draws in the prey

    The effects of shoulder load and pinch force on electromyographic activity and blood flow in the forearm during a pinch task

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    The object of the current study was to determine whether static contraction of proximal musculature has an effect on the blood flow more distally in the upper extremity. Static contractions of muscles in the neck shoulder region at three levels (relaxed, shoulders elevated and shoulders elevated loaded with 4.95 kg each) were combined with intermittent pinch forces at 0, 10 and 25% of the maximum voluntary contraction (MVC). Blood flow to the forearm was measured with Doppler ultrasound. Myoelectric activity of the forearm and neck-shoulder muscles was recorded to check for the workload levels. Across all levels of shoulder load, blood flow increased significantly with increasing pinch force (21% at 10% MVC and by 44% at 25% MVC). Blood flow was significantly affected by shoulder load, with the lowest blood flow at the highest shoulder load. Interactions of pinch force and shoulder load were not significant. The myoelectric activity of forearm muscles increased with increasing pinch force. The activation of the trapezius muscle decreased with increasing pinch force and increased with increasing shoulder load. The precise mechanisms accounting for the influence of shoulder load remains unclear. The results of this study indicate that shoulder load might influence blood flow to the forearm

    phi-Meson production at forward rapidity in p-Pb collisions at root s(NN)=5.02 TeV and in pp collisions at root s=2.76 TeV

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    The first study of phi-meson production in p-Pb collisions at forward and backward rapidity, at a nucleonnucleon centre-of-mass energy root s(NN)= 5.02 TeV, has been performed with the ALICE apparatus at the LHC. The phi-mesons have been identified in the dimuon decay channel in the transverse momentum (p(T)) range 1 <p(T) <7GeV/c, both in the p-going (2.03 <y <3.53) and the Pb-going (-4.46 <y <-2.96) directions - where ystands for the rapidity in the nucleon-nucleon centre-of-mass - the integrated luminosity amounting to 5.01 +/- 0.19nb(-1) and 5.81 +/- 0.20nb(-1), respectively, for the two data samples. Differential cross sections as a function of transverse momentum and rapidity are presented. The forward-backward ratio for f-meson production is measured for 2.96Peer reviewe

    Measurement of D-s(+) product ion and nuclear modification factor in Pb-Pb collisions at root S-NN=2.76 TeV

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