Influence of nontrophic interactions between benthic invertebrates on river sediment processes: a microcosm study

The main objective of this study was to measure the impact of benthic invertebrate diversity on river sediment processes. We quantified the effects of interactions between three taxa (asellids, chironomid larvae, and tubificid worms). The impacts of different taxa richness treatments were measured on sediment reworking, O2 concentrations, bacterial abundances, and numbers of active bacteria in slow filtration sand–gravel columns. The coefficients of sediment reworking measured in multitaxa treatments were lower than those predicted from one-taxon treatments. The interactions among invertebrates also significantly reduced O2 concentrations in sediments. These results were probably due to interactions between the different sediment structures produced by each taxon (tubes, macropores, and fecal pellets) that modified water flow and associated microbial activities in the interstitial habitat. The stimulation of aerobic microbial processes with two- and three-taxa treatments, whereas one-taxon treatments could increase or decrease O2 consumption in columns, indicates that interactions among invertebrates limited the variability of the system functioning. We suggest that, beyond a small number of detritivorous taxa, a threshold effect on bioturbation process and microbial activities was produced by animals in the experimental system. Finally, the interactions between taxa played a significant role in microbial processes in the system studied

Ionization avalanching in clusters ignited by extreme-ultraviolet driven seed electrons

We study the ionization dynamics of Ar clusters exposed to ultrashort near-infrared (NIR) laser pulses for intensities well below the threshold at which tunnel ionization ignites nanoplasma formation. We find that the emission of highly charged ions up to Ar$^{8+}$ can be switched on with unit contrast by generating only a few seed electrons with an ultrashort extreme ultraviolet (XUV) pulse prior to the NIR field. Molecular dynamics simulations can explain the experimental observations and predict a generic scenario where efficient heating via inverse bremsstrahlung and NIR avalanching are followed by resonant collective nanoplasma heating. The temporally and spatially well-controlled injection of the XUV seed electrons opens new routes for controlling avalanching and heating phenomena in nanostructures and solids, with implications for both fundamental and applied laser-matter science.Comment: 5 pages, 4 figure

An Association of Cigarette Smoking with Recurrent Subareolar Breast Abscess

Schäfer P (Department of Gynaecology, University Hospital of Geneva, 24 rue Micheli-du-Crest, 1211 Genève 4, Switzerland), Fürrer C and Merroillod B. An association of cigarette smoking with recurrent subareolar breast abscess. International Journal of Epidemiology 1988, 17: 810-813. In a series of 60 patients suffering from recurrent subareolar breast abscess (RSBA) heavy cigarette smoking was found at an unusually high frequency compared to a control group. In contrast with findings reported in the literature no relation was found with parity, oral contraceptive use or nipple retraction. The strong association of cigarette smoking and RSBA with a relative risk of 9.2 (3.6-23.5) for a light smoker and of 26.4 (9.9-70.2) for a heavy smoker counterbalances possible bias introduced by the retrospective analysis and by the hospital control group. The pathogenesis of RSBA is still not established. Cigarette smoking could have either a direct toxic effect on the retroareolar lactiferous ducts or an indirect effect via hormonal stimulation of the breast secretion; both hypotheses could explain the recurrent aspect of the diseas

Harvesting, coupling and control of single exciton coherences in photonic waveguide antennas

We perform coherent non-linear spectroscopy of individual excitons strongly confined in single InAs quantum dots (QDs). The retrieval of their intrinsically weak four-wave mixing (FWM) response is enabled by a one-dimensional dielectric waveguide antenna. Compared to a similar QD embedded in bulk media, the FWM detection sensitivity is enhanced by up to four orders of magnitude, over a broad operation bandwidth. Three-beam FWM is employed to investigate coherence and population dynamics within individual QD transitions. We retrieve their homogenous dephasing in a presence of spectral wandering. Two-dimensional FWM reveals off-resonant F\"orster coupling between a pair of distinct QDs embedded in the antenna. We also detect a higher order QD non-linearity (six-wave mixing) and use it to coherently control the FWM transient. Waveguide antennas enable to conceive multi-color coherent manipulation schemes of individual emitters.Comment: 7 pages, 8 Figure

Influence of hydraulic conductivity on communities of microorganisms and invertebrates in porous media: a case study in drinking water slow sand filters

Abstract.: The impact of reduced hydraulic conductivity on the abundance and diversity of microorganisms and invertebrates was examined in an artificial ecosystem consisting of a slow sand-filter. Sand-filters processed pre-treated lake water under high flow rates and acted as small ecosystems inhabited by a complex community. The first trophic level consisting of microorganisms serves as a food source for a dense community of protists, micro- and macro-invertebrates. The reduction of hydraulic conductivity due to the development of larger bacterial and fungal biomass induced a shift of the microbial community towards anaerobiosis that may increase clogging by carbonate precipitation. The presence of more bacterial prey seems to favour the development of higher trophic levels. Predation and bioturbation by eukaryotes were not able to counteract the reduction of hydraulic conductivity due to prokaryotic cloggin

Recurrent top-down synaptic connections at different spatial frequencies helpdisambiguate between dynamic emotions

The coarse-to-fine hypothesis posits that, in the Human visualsystem, a coarse representation of visual information is propa-gated quickly through the retina to the cortex, whereas a finer,more detailed representation is propagated more slowly. In aprevious study we showed that recurrent synaptic connectionshelp predict low intensity EFEs. Furthermore, a feedback loopcoming from coarser information processing is postulated toinfluence later processing of finer features. In this paper, weintend to examine the value of coarser information and recur-rence in the processing of dynamic Emotional Facial Expres-sions (EFE). In a step forward in studying the importance ofrecurrent connectivity in the coarse-to-fine model, we testedits advantage for discriminating emotions for different spatialfrequencies and facial expression intensities. Using ArtificialNeural Networks, we modeled recurrent synaptic connectionswith a recurrent feedback loop. Using a Gabor filter bank, wecomputed different levels of spatial frequency features. Our re-sults replicate the advantage of recurrence at first facial expres-sion intensities. Our main finding is that the recurrent model isalso better when predicting high spatial frequencies features.Additionally, mid-to-low spatial frequencies are more usefulto the prediction of EFEs. We conclude that feature process-ing feedback has a significant effect in disambiguating facialexpressions when information is particularly complex, i.e., athigh spatial frequencies and low EFE intensities

Identification of a new expanding family of genes characterized by atypical LRR domains. Localization of a cluster preferentially expressed in oocyte

AbstractIn the present work, we have used the in silico subtraction methodology to identify novel oocyte-specific genes in the mouse. By this way, we have identified in silico a new family of genes composed of more than 80 members. Sequence analysis showed that these genes belong to the superfamily of leucine-rich repeat (LRR) proteins. However, LRRs of this family display some variability in length and in amino acids composition within the β-strands region, as more leucine residues are substituted by other hydrophobic amino acids as compared to canonical LRRs. Interestingly, for nine of these genes, the ESTs were represented almost exclusively in mouse egg libraries. Three of them were selected for experimental study. By RT-PCR and in situ hybridization, we confirmed their specific expression in the mouse oocyte from primary to preovulatory follicles. These three genes are localized in a cluster on mouse chromosome 4, in the vicinity of another recently discovered oocyte specific gene called oogenesin, that we also found to belong to the same family. We thus re-named this latter gene ‘oogenesin-1’, and the three genes identified here were named oogenesin-2, -3 and -4

The Simulation of Smiles (SIMS) model: Embodied simulation and the meaning of facial expression

Recent application of theories of embodied or grounded cognition to the recognition and interpretation of facial expression of emotion has led to an explosion of research in psychology and the neurosciences. However, despite the accelerating number of reported findings, it remains unclear how the many component processes of emotion and their neural mechanisms actually support embodied simulation. Equally unclear is what triggers the use of embodied simulation versus perceptual or conceptual strategies in determining meaning. The present article integrates behavioral research from social psychology with recent research in neurosciences in order to provide coherence to the extant and future research on this topic. The roles of several of the brain's reward systems, and the amygdala, somatosensory cortices, and motor centers are examined. These are then linked to behavioral and brain research on facial mimicry and eye gaze. Articulation of the mediators and moderators of facial mimicry and gaze are particularly useful in guiding interpretation of relevant findings from neurosciences. Finally, a model of the processing of the smile, the most complex of the facial expressions, is presented as a means to illustrate how to advance the application of theories of embodied cognition in the study of facial expression of emotion.Peer Reviewe