Gelatinous macrozooplankton diversity and distribution dataset for the North Sea and Skagerrak/Kattegat during January-February 2021

This data article includes a qualitative and quantitative description of the gelatinous macrozooplankton community of the North Sea during January-February 2021. Sampling was conducted during the 1 st quarter International Bottom Trawl Survey (IBTS) on board the Danish R/V DANA (DTU Aqua Denmark) and the Swedish R/V Svea (SLU Sweden), as part of the ichthyoplankton investigation during night-time. A total of 147 stations were investigated in the western, central and eastern North Sea as well as the Skagerrak and Kattegat. Sampling was conducted with a 13 m long Midwater Ring Net (MIK net, O 2 m, mesh size 1.6 mm, cod end with smaller mesh size of 500 mu m), equipped with a flow meter. The MIK net was deployed in double oblique hauls from the surface to c. 5 m above the sea floor [1 , 2] . Samples were visually analysed unpreserved on a light table and/or with a stereomicroscope or magnifying lamp within 2 hours after catch. A total of 13,510 individuals were counted/sized. Twelve gelatinous macrozooplankton species or genera were encountered, namely the hydrozoan Aequorea vitrina, Aglantha digitale, Clytia spp., Leuckartiara octona, Tima bairdii, Muggiaea atlantica ; the scyphozoans Cyanea capillata and Cyanea lamarckii and the ctenophores Beroe spp., Bolinopsis infundibulum, Mnemiopsis leidyi, Pleurobrachia pileus . Abundance data are presented on a volume specific (m -3 ) and area specific (m -2 ) basis. Size data have been used to estimate wet weights based on published length-weight regressions (see Table 1). For the groups i) hydrozoan jellyfish, ii) scyphozoan jellyfish, iii) ctenophores, as well as iv) grouped gelatinous macrozooplankton, spatial weight specific distribution patterns are presented. This unpublished dataset contributes baseline information about the gelatinous macrozooplankton diversity and its specific distribution patterns in the extended North Sea area during winter (January-February) 2021. These data can be an important contribution to address global change impacts on marine systems, especially considering gelatinous macrozooplankton abundance changes in relation to anthropogenic stressors.(c) 2022 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY licens

Deterministic single-photon source from a single ion

We realize a deterministic single-photon source from one and the same calcium ion interacting with a high-finesse optical cavity. Photons are created in the cavity with efficiency (88 +- 17)%, a tenfold improvement over previous cavity-ion sources. Results of the second-order correlation function are presented, demonstrating a high suppression of two-photon events limited only by background counts. The cavity photon pulse shape is obtained, with good agreement between experiment and simulation. Moreover, theoretical analysis of the temporal evolution of the atomic populations provides relevant information about the dynamics of the process and opens the way to future investigations of a coherent atom-photon interface

Active reset of a radiative cascade for entangled-photon generation beyond the continuous-driving limit

The emission rate of entangled photons from cascaded few-level systems is limited by the dynamics of the radiative transitions. Here, we overcome the continuous driving limit for a semiconductor quantum dot via an active reset of the radiative cascade. We show theoretically and experimentally the driving regime to enable the generation of entangled photon pairs with higher fidelity and emission rate than the optimum continuously driven state. Finally, we electrically generate entangled photon pairs with an average fidelity of (79.5±1.1)% at a record clock rate of 1.15 GHz

Heralded single photon absorption by a single atom

The emission and absorption of single photons by single atomic particles is a fundamental limit of matter-light interaction, manifesting its quantum mechanical nature. At the same time, as a controlled process it is a key enabling tool for quantum technologies, such as quantum optical information technology [1, 2] and quantum metrology [3, 4, 5, 6]. Controlling both emission and absorption will allow implementing quantum networking scenarios [1, 7, 8, 9], where photonic communication of quantum information is interfaced with its local processing in atoms. In studies of single-photon emission, recent progress includes control of the shape, bandwidth, frequency, and polarization of single-photon sources [10, 11, 12, 13, 14, 15, 16, 17], and the demonstration of atom-photon entanglement [18, 19, 20]. Controlled absorption of a single photon by a single atom is much less investigated; proposals exist but only very preliminary steps have been taken experimentally such as detecting the attenuation and phase shift of a weak laser beam by a single atom [21, 22], and designing an optical system that covers a large fraction of the full solid angle [23, 24, 25]. Here we report the interaction of single heralded photons with a single trapped atom. We find strong correlations of the detection of a heralding photon with a change in the quantum state of the atom marking absorption of the quantum-correlated heralded photon. In coupling a single absorber with a quantum light source, our experiment demonstrates previously unexplored matter-light interaction, while opening up new avenues towards photon-atom entanglement conversion in quantum technology.Comment: 10 pages, 4 figure

Biodiversity modelling in practice - predicting bird and woody plant species richness on farmlands

In light of decreasing species richness on farmland and an increasing awareness of biodiversity issues among customers and food companies, concepts and models to evaluate and enhance farmland biodiversity are greatly needed. It is important that the models are easy to apply as they have to be utilized by practitioners such as farmers and their consultants. In this study, simple but valid predictors were identified to rapidly assess the species richness of birds and woody plants in hedgerows, an important farmland landscape element. Hedgerows were sampled in seven agricultural landscapes throughout Germany. By means of automatic model selection procedures, linear regression models were estimated to predict bird and woody plant species richness. Cross validation procedures were carried out in order to visualize model selection uncertainty and estimate the prediction error. Due to a rather high prediction error, the model for plants can only be recommended for use when field work is not feasible. The model for birds, however, explained 70.8% of the variance in species numbers. It may help farmers, food companies and nature conservation agencies to rapidly evaluate bird species richness in hedgerows on farmland and to identify potentials and appropriate measures for enhancing it

Intestinal ischemia after cardiac surgery: analysis of a large registry.

Intestinal ischemia after cardiac surgery is a rare but severe complication with a high mortality. Early surgery can be lifesaving. The aim was to analyze the incidence, outcome, and risk factors for these patients