Interaction-induced adiabatic non-linear transport

We calculate the time-dependent non-linear transport current through an interacting quantum dot in the single-electron tunneling regime (SET). We show that an additional dc current is generated by the electron-electron interaction by adiabatic out-of-phase modulation of the gate and bias voltage. This current can arise only when two SET resonance conditions are simultaneously satisfied. We propose an adiabatic transport spectroscopy where lock-in measurement of a "time-averaged stability diagram" probes interactions, tunnel asymmetries and changes in the ground state spin-degeneracy.Comment: 4 pages, 2 figure

Dealing with Diversity in English Children's Books in the Heterogeneous EFL Classroom

The use of children’s literature in language teaching is very common. However, in view of heterogeneous English as a foreign language (EFL) classrooms with learners of different interests, abilities, preferences, competences, identities, beliefs, etc., approaches to dealing with literature need to be supplemented by carefully selected scaffolds to cater to individual learner needs. Yet, it is not just the teaching methods that need to be (re)considered with regards to teaching a heterogeneous learner group, but also the topics that are covered in class should be carefully selected. Children’s books offer a wide range of topics that are commonly dealt with in the EFL classroom with younger learners. Some books, classic as well as recent ones, also depict different aspects of diversity. Such pieces of literature offer the potential to discuss diversity with learners in the EFL classroom and can serve as a basis for negotiations of diversity at the content-level. Therefore, this article deals with a two-fold question on aspects of diversity:             (1) How do selected English children’s books represent or mirror diversity?      (2) Can such books be used successfully in the heterogeneous EFL classroom

Flow sorting in aquatic ecology

Flow sorting can be a very helpful tool in revealing phytoplankton and bacterial community structure and elaborating specific physiological parameters of isolated species. Droplet sorting has been the most common technique. Despite the high optical and hydro-dynamic stress for the cells to be sorted, many species grow in culture subsequent to sorting. To date, flow sorting has been applied to post-incubation separation in natural water samples to account for group-specific physiological parameters (radiotracer-uptake rates), to the production of clonal or non-clonal cultures from mixtures, to the isolaton of cell groups from natural assemblages for molecular analyses, and for taxonomic identification of sorted cells by microscopy. The application of cell sorting from natural water samples from the Wadden Sea, including different cryptophytes, cyanobacteria and diatoms, is shown, as well as the establishment of laboratory cultures from field samples. The optional use of a red laser to account for phycocyanine-rich cells is also discussed.No disponibl

Trophic interactions between picophytoplankton and micro- and nanozooplankton in the western Arabian Sea during the NE monsoon 1993

The grazing pressure of micro- and nanozooplankton on phytoplankton was estimated in serial dilution experiments in the northwestern Arabian Sea and its adjacent areas (the Somali Current, the Somali Basin, the Gulf of Aden and the southern Red Sea) during the NE monsoon 1992-1993. Microzooplankton grazing rates (g) on total phytoplankton (analyzed as chi a) were generally exceeded by phytoplankton growth rates (g = 0.2 to 1.19 d(-1), mean 0.48 d(-1); mu = 0.52 to 1.12 d(-1), mean 0.72 d(-1)), resulting in an average daily consumption of 38 % of the phytoplankton standing stock and 67 % of the primary production. Microzooplankton grazing on 4 picophytoplankton groups (Prochlorococcus spp., Synechococcus spp., and 2 picoeukaryotes) analyzed by flow cytometry showed growth (mu = 0.27 to 0.92 d(-1), mean 0.68 d(-1)) and grazing mortality rates (g = 0.26 to 0.73 d(-1), mean 0.67 d(-1)) well in balance, with an average of 49 % of the standing stock and 102% of the primary production grazed per day. Picophytoplankton growth and grazing mortality rates increased dramatically when grazers >10 mu m were removed. These results suggest a control of the small grazers by larger ones (trophic cascade) and a close coupling between picoautotrophic prey and small grazers. The trophic cascade within the microbial food web of the nanoplankton encompasses 3 trophic levels: picoplankton - small HNF - larger flagellates and ciliates

Transport signature of pseudo-Jahn-Teller dynamics in a single-molecule transistor

We calculate the electronic transport through a molecular dimer, in which an excess electron is delocalized over equivalent monomers, which can be locally distorted. In this system the Born-Oppenheimer approximation breaks down resulting in quantum entanglement of the mechanical and electronic motion. We show that pseudo Jahn-Teller (pJT) dynamics of the molecule gives rise to conductance peaks that indicate this violation. Their magnitude, sign and position sharply depend on the electro-mechanical properties of the molecule, which can be varied in recently developed three-terminal junctions with mechanical control. The predicted effect depends crucially on the degree of intramolecular delocalization of the excess electron, a parameter which is also of fundamental importance in physical chemistry.Comment: 6 pages, 3 figure

Phaeocystis blooming enhanced by copepod predation on protozoa: evidence from incubation experiments

Laboratory experiments were carried out to investigate the effect of protozoan, copepod and combined grazing on Phaeocystis biomass. Phaeocystis cf. globosa single cells were offered to 3 different protozoan species, to the calanoid copepod Temora longicornis, as well as to mixtures of both grazer types. The heterotrophic dinoflagellate Oxyrrhis marina and the oligotrich ciliate Strombidinopsis acuminatum ingested Phaeocystis at much higher rates than did the copepod. Nevertheless, protozoan growth and ingestion rates were submaximal, indicating Phaeocystis to be suboptimal food. The oligotrich ciliate Strombidium elegans did not feed on Phaeocystis. In grazing experiments with mixtures of both predator types, the decline of Phaeocystis single cells could be explained by protozoan grazing alone, implying no grazing by the copepods on Phaeocystis. Instead, copepods ingested the protozoans at high rates. Predation on 0. marina and S. acuminatum by T. longicornis resulted in a reduction of the total grazing pressure on Phaeocystis of 21 and 67 % respectively. We conclude that mesozooplankton predation on herbivorous ciliates and heterotrophic dinoflagellates, which consumed Phaeocystis cells, can considerably reduce the overall grazing pressure and may enhance Phaeocystis bloomng

Vibrational detection and control of spin in mixed-valence molecular transistors

We investigate electron transport through a mixed-valence molecular complex in which an excess electron can tunnel between hetero-valent transition metal ions, each having a fixed localized spin. We show that in this class of molecules the interplay of the spins and the vibrational breathing modes of the ionic ligand-shells allows the total molecular spin to be detected as well as controlled by nonequilibrium transport. Due to a spin-dependent pseudo Jahn-Teller effect electronic transitions with different spin values can be distinguished by their vibronic conductance side peaks, without using an external magnetic field. Conversely, we show that the spin state of the entire molecule can also be controlled via the nonequilibrium quantized molecular vibrations due to a vibration-induced spin-blockade.Comment: 6 pages, 3 figure