It has been known for centuries that floral and extra-floral nectar secreted by plants attracts and rewards animals. Extra-floral nectar is involved in so-called indirect defense by attracting ...animals (generally ants) that prey on herbivores, or by discouraging herbivores from feeding on the plant. Floral nectar is presented inside the flower close to the reproductive organs and rewards animals that perform pollination while visiting the flower. In both cases nectar is a source of carbon and nitrogen compounds that feed animals, the most abundant solutes being sugars and amino acids. Plant-animal relationships involving the two types of nectar have therefore been used for a long time as text-book examples of symmetric mutualism: services provided by animals to plants in exchange for food provided by plants to animals. Cheating (or deception or exploitation), namely obtaining the reward/service without returning any counterpart, is however, well-known in mutualistic relationships, since the interacting partners have conflicting interests and selection may favor cheating strategies. A more subtle way of exploiting mutualism was recently highlighted. It implies the evolution of strategies to maximize the benefits obtained by one partner while still providing the reward/service to the other partner. Several substances other than sugars and amino acids have been found in nectar and some affect the foraging behavior of insects and potentially increase the benefits to the plant. Such substances can be considered plant cues to exploit mutualism. Recent evidence motivated some authors to use the term "manipulation" of animals by plants in nectar-mediated mutualistic relationships. This review highlights the recent background of the "manipulation" hypothesis, discussing it in the framework of new ecological and evolutionary scenarios in plant-animal interactions, as a stimulus for future research.
The uncontrolled introduction into the environment of plastic polymers have caused the dispersion of plastic fragments, known as Microplastics (MPs), that represent an important topic for public ...health. This study was the first to investigate the cause of the release of MPs in mineral waters and to estimate the concentration of MPs smaller than 10 μm both in number of particles and in mass unit. This study was carried out using a patent method regarding the extraction and analysis of MPs in more kind of matrix. Therefore, aims of this study were a) to assess the number of MPs with diameters of between 0.5 and 10 μm in mineral waters contained in plastic bottles, b) to evaluate if the physical-chemical properties of mineral waters and bottle quality could influence the release of MPs and, finally, c) to estimate the human daily exposure to MPs due to mineral water consumption.
The Mps were found in every sample. The main concentration of MPs was 656.8 μg/L ± 632.9 or 5.42E+07 p/L ± 1.95E+07. The main diameter of detected MPs was 2.44 μm ± 0.66 (where p/L, where p was the number of MPs). The Estimated Daily Intake (EDI) for adults and children were 1,531,524 p/kg/body-weight/day corresponding to 40.1 μg/kg/body-weight/day and 3,350,208 p/kg/body-weight/day corresponding to 87.8 μg/kg/body-weight/day, respectively.
The number of MPs contamination in bottled mineral waters was strongly correlated to the pH of waters and to plastic density of bottle. Otherwise, micrograms of MPs per liter and the MPs diameters were strongly affected by plastic thickness. The most mineral water brand contaminated by MPs was the one whose bottles were made from poor quality plastic.
In absence of reference values, it was no possible carried out a risk assessment for MPs exposure. It is fundamental to establish the reference method of analysis to monitoring every source of human intake.
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•New patent method of extraction and analysis of Microplastics.•Estimation of the concentration of Microplastics smaller than 10 μm both in number of particles and in mass unit.•Influence of physical-chemical properties of mineral waters and bottle quality on release of Microplastics.•Estimated Daily Intake of Microplastics for adults and children.
This brief presents a novel charge pump suitable to work under very-low-voltage supply. The circuit exploits a novel charge transfer switch made up by the combination of a NMOS and a PMOS transistor ...whose gates are connected to internal nodes of the charge pump to enhance overdrive voltage. This solution allows working with supply voltage values lower that the MOS threshold voltage. Post layout simulation results using a 65-nm CMOS standard technology show the effectiveness of the proposed solution and its advantage as compared to a traditional latched charge pump in terms of high current driving range, power efficiency and speed.
In this work, we identified the trail pheromone of the ant Crematogaster scutellaris. We combined gas chromatography-mass spectrometry analysis of extracts from the hind tibia, the location of the ...respective glands, with automated trail following assays. The study found tridecan-2-ol to be the strongest discriminator between hind tibia and other body part extracts. Tridecan-2-ol elicited trail-following behaviour at concentrations of 1 ng/µL. A separation of the enantiomers showed responses to (R)-tridecan-2-ol already at 0.001 ng/µL and only at a 1000-fold higher concentration for (S)-tridecan-2-ol, suggesting that only the R enantiomer is used by C. scutellaris in its natural environment. We also found strong behavioural responses to 2-dodecanol, a substance that was not detectable in the hind tibia extract of C. scutellaris, but which has been reported to be the trail pheromone of the related species C. castanea. We discuss the contribution of these results to the 'dissection and reconstruction' of strategies and mechanisms underlying the social organization of ants.
In this brief an improved Dickson charge pump (DCP) topology exploiting a clock boosting is presented. An accurate while simple theoretical model for the dynamic behavior of the charge pump is ...carried out. Analytical comparison with the traditional DCP reveals that the proposed solution can achieve a rise time or area reduction between 10% and 60% at the cost of a slight circuit complexity. Finally, simulation results using a 65-nm CMOS technology show the accuracy of the analytical model as well as the advantages of the proposed solution.
Much research has revealed the human visual system is capable to estimate numerical quantities, rapidly and reliably, in both the spatial and the temporal domain. This ability is highly susceptible ...to short-term plastic phenomena related to previous exposure to visual numerical information (i.e., adaptation). However, while determinants of spatial numerosity adaptation have been widely investigated, little is known about the neural underpinnings of short-term plastic phenomena related to the encoding of temporal numerical information. In the present study we investigated the electrophysiological correlates of temporal numerosity adaptation.
Participants were asked to estimate the numerosity of a test sequence of flashes after being exposed to either a high or low numerous adapting sequence. Behavioral results confirmed the expected underestimation of test stimulus when this was preceded by a high numerous sequence as compared to when preceded by a low numerous sequence.
Electrophysiological data revealed that this behavior was tightly linked to the amplitude of the steady-state visual evoked (ssVEP) response elicited by the test stimulus. When preceded by a high numerous sequence, the test stimulus elicited larger ssVEP responses as compared to when preceded by a low numerous sequence with this pattern being robustly correlated with behavior. Finally, topographical maps showed that this difference was mostly evident across two antero-posterior distributed clusters of electrodes and correlated with changes in functional connectivity.
Taken together, our results suggest that visual plastic phenomena related to the encoding of temporal numerosity information reflect changes in rhythmic evoked activity that are likely related to long range communications between distinct brain regions.
In the present study we tested the effects of different transcranial direct current stimulation (tDCS) protocols in the formation of visuo-spatial contextual learning (VSCL). The study comprised ...three experiments designed to evaluate tDCS-induced changes in VSCL measures collected during the execution of a visual search task widely used to examine statistical learning in the visuo-spatial domain. In Experiment 1, we probed for the effects of left-posterior parietal cortex (PPC) anodal-tDCS (AtDCS) at different timings (i.e. offline and online) and intensities (i.e. 3 mA and 1.5 mA). The protocol producing the more robust effect in Experiment 1 was used in Experiment 2 over the right-PPC, while in Experiment 3, cathodal-tDCS (CtDCS) was applied over the left-PPC only at a high intensity (i.e. 3 mA) but varying timing of application (offline and online). Results revealed that high intensity offline AtDCS reduced VSCL regardless of the stimulation side (Experiment 1 and 2), while no significant behavioral changes were produced by both online AtDCS protocols (Experiment 1) and offline/online CtDCS (Experiment 3). The reduced VSCL could result from homeostatic regulatory mechanisms hindering normal task-related neuroplastic phenomena.
Numerosity perception is a key ability for human and non-human species, probably mediated by dedicated brain mechanisms. Electrophysiological studies revealed the existence of both early and ...mid-latency components of the Electrophysiological (EEG) signal sensitive to numerosity changes. However, it is still unknown whether these components respond to physical or perceived variation in numerical attributes. We here tackled this point by recording electrophysiological signal while participants performed a numerosity adaptation task, a robust psychophysical method yielding changes in perceived numerosity judgments despite physical numerosity invariance. Behavioral measures confirmed that the test stimulus was consistently underestimated when presented after a high numerous adaptor while perceived as veridical when presented after a neutral adaptor. Congruently, EEG results revealed a potential at around 200 ms (P2p) which was reduced when the test stimulus was presented after the high numerous adaptor. This result was much prominent over the left posterior cluster of electrodes and correlated significantly with the amount of adaptation. No earlier modulations were retrievable when changes in numerosity were illusory while both early and mid-latency modulations occurred for physical changes. Taken together, our results reveal that mid-latency P2p mainly reflects perceived changes in numerical attributes, while earlier components are likely to be bounded to the physical characteristics of the stimuli. These results suggest that short-term plastic mechanisms induced by numerosity adaptation may involve a relatively late processing stage of the visual hierarchy likely engaging cortical areas beyond the primary visual cortex. Furthermore, these results also indicate mid-latency electrophysiological correlates as a signature of the internal representation of numerical information.
The predatory ability of ants (Hymenoptera, Formicidae) against insect pests can offer an important service to agricultural activities and may sometimes be directly exploited in biological control ...strategies. The codling moth
(Lepidoptera, Tortricidae) is a major agricultural pest of fruit orchards, whose biological control is complicated by the fact that the larvae spend most of their life protected within the fruits they damage. In a recent experiment in Europe, pear trees in which ant activity was artificially increased by the addition of sugary liquid dispensers (artificial nectaries) suffered less damage caused by the larvae to their fruits. While some ants were already known to prey upon the mature larvae or pupae of
in the soil, prevention of fruit damage would require predation upon eggs or newly hatched larvae, which have not yet excavated into the fruits. We verified whether two different Mediterranean ants frequently observed in fruit orchards,
and
, were able to prey upon
eggs and larvae in laboratory conditions. Our experiments demonstrated that both species similarly attacked and killed young
larvae. On the other hand, the eggs mostly attracted the attention of
but were never damaged. Further field assessments are required to understand whether ants may also interfere with oviposition by adults or whether larger ant species, although generally rarer in orchards, may also prey upon eggs.
This brief presents the experimental validation of a low-power, large output swing, class-AB buffer amplifier for column drivers of active-matrix flat-panel displays. By exploiting two complementary ...input amplifiers and a dual-path push-pull output stage, the proposed circuit achieves high-drive performance and rail-to-rail operation. In addition, two current boosters allow area optimization of the output diving transistors by dynamically lowering their threshold voltage. Implemented in a standard triple-well CMOS 0.35-<inline-formula> <tex-math notation="LaTeX">{\mu }{\text{m}} </tex-math></inline-formula> technology and supplied from a 3-V supply, the proposed buffer amplifier can drive a 1-nF column line load within a 1.11-<inline-formula> <tex-math notation="LaTeX">{\mu }\text{s} </tex-math></inline-formula> settling time under a full voltage swing, while drawing only 1.6 <inline-formula> <tex-math notation="LaTeX">{\mu }\text{A} </tex-math></inline-formula> quiescent current and occupying 5562 <inline-formula> <tex-math notation="LaTeX">{\mu }{\text{m}}^{{2}} </tex-math></inline-formula> of silicon area. As compared to the state of the art, the best figure of merit (pF/<inline-formula> <tex-math notation="LaTeX">{\mu }\text{s}{\cdot } {\mu }\text{A} </tex-math></inline-formula>) is found.
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