Aromatic Rich Natural Organic Matter Increases Growth and Reduces Nickel Toxicity in a Wild Daphnia Hybrid

Natural organic matter (NOM) is on the rise across the Shield. Its heterogeneous, amalgamate nature makes each NOM source potentially unique. Relatively little is known about the direct effects distinct NOM sources have on daphniids, or the varying protection NOM provides against metal toxicity –specifically Ni. I show that NOM from different natural sources increases growth rates and decreases time to maturation of Daphnia to various degrees. These changes relate to aromatic content of NOM isolates, the mechanism most likely being a hormonal effect or mild oxidative stress. Aromatic content (representing phenolic groups) is also positively related to Ni mitigation for those isolates with specific UV absorbance below 19.3 cm2mg-1. Incorporating NOM aromatic content into a predictive model improves the relationship between predicted and measured LC50s by 5%. I demonstrate that structural differences between NOM isolates relating to aromatic content play a major role in their effects on Daphnia

Cavity-Controlled Collective Scattering at the Recoil Limit

We study collective scattering with Bose-Einstein condensates interacting with a high-finesse ring cavity. The condensate scatters the light of a transverse pump beam superradiantly into modes which, in contrast to previous experiments, are not determined by the geometrical shape of the condensate, but specified by a resonant cavity mode. Moreover, since the recoil-shifted frequency of the scattered light depends on the initial momentum of the scattered fraction of the condensate, we show that it is possible to employ the good resolution of the cavity as a filter selecting particular quantized momentum states.Comment: 4 pages, 4 figure

Monitoring cortical excitability during repetitive transcranial magnetic stimulation in children with ADHD: a single-blind, sham-controlled TMS-EEG study

Background: Repetitive transcranial magnetic stimulation (rTMS) allows non-invasive stimulation of the human brain. However, no suitable marker has yet been established to monitor the immediate rTMS effects on cortical areas in children. Objective: TMS-evoked EEG potentials (TEPs) could present a well-suited marker for real-time monitoring. Monitoring is particularly important in children where only few data about rTMS effects and safety are currently available. Methods: In a single-blind sham-controlled study, twenty-five school-aged children with ADHD received subthreshold 1 Hz-rTMS to the primary motor cortex. The TMS-evoked N100 was measured by 64-channel-EEG pre, during and post rTMS, and compared to sham stimulation as an intraindividual control condition. Results: TMS-evoked N100 amplitude decreased during 1 Hz-rTMS and, at the group level, reached a stable plateau after approximately 500 pulses. N100 amplitude to supra-threshold single pulses post rTMS confirmed the amplitude reduction in comparison to the pre-rTMS level while sham stimulation had no influence. EEG source analysis indicated that the TMS-evoked N100 change reflected rTMS effects in the stimulated motor cortex. Amplitude changes in TMS-evoked N100 and MEPs (pre versus post 1 Hz-rTMS) correlated significantly, but this correlation was also found for pre versus post sham stimulation. Conclusion: The TMS-evoked N100 represents a promising candidate marker to monitor rTMS effects on cortical excitability in children with ADHD. TMS-evoked N100 can be employed to monitor real-time effects of TMS for subthreshold intensities. Though TMS-evoked N100 was a more sensitive parameter for rTMS-specific changes than MEPs in our sample, further studies are necessary to demonstrate whether clinical rTMS effects can be predicted from rTMS-induced changes in TMS-evoked N100 amplitude and to clarify the relationship between rTMS-induced changes in TMS-evoked N100 and MEP amplitudes. The TMS-evoked N100 amplitude reduction after 1 Hz-rTMS could either reflect a globally decreased cortical response to the TMS pulse or a specific decrease in inhibition

Trophic cascades initiated by fungal plant endosymbionts impair reproductive performance of parasitoids in the second generation

Variation in plant quality can transmit up the food chain and may affect herbivores and their antagonists in the same direction. Fungal endosymbionts of grasses change the resource quality by producing toxins. We used an aphid-parasitoid model system to explore how endophyte effects cascade up the food chain and influence individual parasitoid performance. We show that the presence of an endophyte in the grass Lolium perenne has a much stronger negative impact on the performance of the parasitoid Aphidius ervi than on its aphid host Metopolophium festucae. Although the presence of endophytes did not influence the parasitism rate of endophyte-naïve parasitoids or their offspring's survival to adulthood, most parasitoids developing within aphids from endophyte-infected plants did not reproduce at all. This indicates a delayed but very strong effect of endophytes on parasitoid performance, which should ultimately affect plant performance negatively by releasing endophyte-tolerant herbivores from top-down limitation

Weighted Clément operator and application to the finite element discretization of the axisymmetric Stokes problem

We consider the Stokes problem in an axisymmetric three-dimensional domain with data which are axisymmetric and have angular component equal to zero. We observe that the solution is also axisymmetric and the velocity has also zero angular component, hence the solution satisfies a system of equations in the meridian domain. The weak three-dimensional problem reduces to a two-dimensional one with weighted integrals. The latter is discretized by Taylor-Hood type finite elements. A weighted Clément operator is defined and approximation results are proved. This operator is then used to derive the discrete inf-sup condition and optimal a priori error estimate

High-resolution mutagenesis of the linker domain of archaeal basal transcription factor TFIIB

TFIIB is a component of the minimal eukaryotic as well as the archaeal transcriptional machinery that is essential for promoter-directed transcription. The flexible linker domain of the protein engages in an intimate association with the RNA polymerase surface. Early structural data suggested that the linker forms a finger-like structure (the ‘B-finger’) within the RNA exit channel projecting into the active centre. Biochemical data indicated a contribution of the archaeal ‘B-finger’ domain to the catalytic mechanism by stimulating abortive transcription. The path of the linker within the RNA polymerase catalytic centre has recently been re-assessed and residues of the original Bfinger were re-assigned to structural elements named ‘B-reader helix’ and ‘B-reader loop’. Novel high-throughput tools, in combination with a comprehensive mutagenesis screen of residues E78 to A95, facilitated the biochemical evaluation of structural-functional relationships of the M. jannaschii TFIIB linker – RNAP interface at a single residue resolution. The performance of such point mutants during abortive initiation and RNA polymerase recruitment was interpreted in light of structural information. The tip region of the ‘B-finger’ that was predicted to be closest to the active site was insensitive to mutations in abortive initiation assays, thus disproving the original model. Individual residues, forming part of the B-reader helix and the C-terminal half of the Breader loop, were found to engage in abortive transcription. Three-residue deletions within the N-terminal half of the B-reader loop resulted in super-stimulation of abortive transcription. Individual point mutations within the B-reader loop led to enhanced recruitment of RNA polymerase. A functional role of the loop in stabilizing TFIIBRNA polymerase-DNA complexes in both the absence and presence of TBP seems feasible. The combined data provide a detailed view of biochemical functions of individual residues of the TFIIB linker favouring the ‘B-reader’ model over the ‘B-finger’ model

Students\u27 View on Instant Online Feedback for Presentations

This paper presents an empirical study investigating the use of instant online feedback on face-to-face presentations. This innovative way of using information technology for the specific communication purpose of giving feedback was researched in the context of a university course on “Human-Computer Interaction and Psychology”. A total sum of 80 students majoring in Computer Science participated in the instant online feedback activity and 907 feedbacks were given. 72 students returned the questionnaire for evaluating this educational scenario. Quantitative and qualitative analysis revealed that students seem to prefer giving feedback online in addition to a face-to-face setting for reasons like possible anonymity and more honesty. Study results further demonstrate that instant online feedback may facilitate students\u27 interest in and commitment to their presentations, finally also increasing their contributions\u27 quality