Improved nanopatterning for YBCO nanowires approaching the depairing current

An improved nanopatterning procedure has been developed to obtain YBCO nanowires with cross sections as small as 50x50 nm^2, protected by an Au capping layer. To probe the effective role of the Au protecting layer, we have measured the current-voltage characteristics and the resistive transition in temperature of the nanowires. Critical current densities up to 10^8 A/cm^2 have been achieved at T=4.2 K, approaching the theoretical depairing current limit. The resistance, measured as a function of temperature close to Tc, has been fitted with a thermal activated phase slip model, including the effect of the gold layer. The extracted values of the superconducting coherence length and of the London penetration depth give current densities consistent with the measured ones. These results cannot be achieved with same nanowires, without the Au capping layer.Comment: ASC 2012 conference contributio

Seasonal patterns in butterfly abundance and species diversity in five characteristic habitats in Sites of Community Importance in Sicily (Italy)

Sicily (Italy) is one of the richest European regions in animal biodiversity. Butterflies offer good opportunities for studies on biodiversity , population and community ecology. Many species are strictly seasonal, preferring only a particular set of habitats. Five typical Mediterranean habitats: olive grove (conducted following organic farm management), mixed wood, ampelodesmos prairie (with dominance of Ampelodesmos mauritanicus), Mediterranean shrub and shrub at the coastal areas, were monitored for diversity and seasonal patterns in butterfly communities for 2 years. All habitats were inside protected areas indicated as Sites of Community Importance. Butterfly species richness was highest in ampelodesmos prairie and in olive grove. Pieris brassicae, Lasiommata megera, Maniola jurtina, Pararge aegeria have been reported in all habitats, although with different abundance whilst other species were observed only in one particular habitat. Melanargia pherusa, endemic species, and Hipparchia statil-inus, listed in the IUCN Red List, respectively as " Least Concern " and " Near Threatened " , were observed in the ampelodesmos prairie. The morphotype Coenonympha pamphilus f. lyllus was reported in olive grove and ampelodesmos prairie. The majority of species showed abundance peaks in June and July, however many species showed a longer flight period than reported in literature with detection of specimens until November or December. The analysis of the similarity of communities among habitats shows a similarity between ampelodesmos prairie and olive grove and between Mediterranean shrub and Mediterranean shrub at the coastal areas, while the butterfly community in mixed wood is substantially different. The results of several diversity indexes suggest that ampelodesmos prairie has an important ecological role, as it supports butterfly abundance and species diversity

Wearable Brain-Computer Interface Instrumentation for Robot-Based Rehabilitation by Augmented Reality

An instrument for remote control of the robot by wearable brain-computer interface (BCI) is proposed for rehabilitating children with attention-deficit/hyperactivity disorder (ADHD). Augmented reality (AR) glasses generate flickering stimuli, and a single-channel electroencephalographic BCI detects the elicited steady-state visual evoked potentials (SSVEPs). This allows benefiting from the SSVEP robustness by leaving available the view of robot movements. Together with the lack of training, a single channel maximizes the device's wearability, fundamental for the acceptance by ADHD children. Effectively controlling the movements of a robot through a new channel enhances rehabilitation engagement and effectiveness. A case study at an accredited rehabilitation center on ten healthy adult subjects highlighted an average accuracy higher than 83%, with information transfer rate (ITR) up to 39 b/min. Preliminary further tests on four ADHD patients between six- and eight-years old provided highly positive feedback on device acceptance and attentional performance

Transgenic resistance of eggplants to the Colorado potato beetle

The subject of this thesis is the use of transgenic plant resistance as a method to control the Colorado potato beetle, Leptinotarsa decemlineata Say in eggplant. The gene conferring resistance is coding for a Cry3B toxin and it is a synthetic version of a wild-type gene originally obtained from the soil bacterium Bacillus thuringiensis Berl.Eggplant cultivations are constantly attacked by a number of serious pests (e.g. the fruit and shoot borer, the Colorado potato beetle, soil-borne fungi). In spite of the heavy losses they may cause, breeding for resistance on this crop has been very limited because of the lack of desirable traits in the eggplant genome or sexual incompatibility with the resistant wild related species.The first chapter reviews Colorado potato beetle biology and its control, with a special emphasis on beetle-eggplant relationships. L. decemlineata has become a major problem for eggplant cultivation and sometimes its control on this crop is even more problematic compared to potato cultivation. The longer life cycle of the plant and the intensive regime under which horticultural crops are cultivated have contributed to the increasing importance of this pest.In the second chapter, a review of the source of resistant genes available in both the eggplant gene pool and wild Solanum relatives is presented. Considering the genetic basis of resistant traits, the possible strategies for eggplant breeding are discussed with emphasis on approaches based on the integration of classical breeding methods (crosses and selection) with biotechnological ones (anther culture, genetic transformation, protoplast fusion and marker-assisted selection).In the third chapter, the results of the study in which protein extracts of Escherichia coli expressing the toxin gene from B. thuringiensis were tested for effect on the behavior and development of L. decemlineata larvae using in vitro bioassays are presented. No antifeedant effect due to Cry3B toxin was found, even in concentrations which caused mortality or severely inhibited larval growth.In the fourth chapter, the production of transgenic eggplants and their evaluation is presented. A modified Bt gene of Bacillus thuringiensis var. Tolworthi, encoding a coleopteran insect-specific Cry3B toxin, was transferred via Agrobacterium tumefaciens to the female parent of the commercial F1 hybrid 'Rimina' eggplant (released by the Istituto Sperimentale per l'Orticoltura). A large number of transgenic plants were regenerated and tested by PCR and NPTII expression assays. The presence of the Cry3B toxin in leaf extracts was demonstrated by the DAS-ELISA test in 57 (62.3%) transgenic plants which contained a 74 kDa protein cross-reacting with the serum anti-Cry3B toxin. Twenty-three out of 44 S. melongena plants tested by an insect bioassay showed a significant insecticidial activity on neonate larvae of Colorado Potato Beetle (CPB). The Bt transgene and the toxic effect on CPB larvae were transmitted to progenies derived by selfing. Thus, transgenic Bt eggplants may represent a very effective means of CPB pest control.Transgenic potato clones expressing a Cry3B endotoxin were used to study the trophic interactions between newly emerged Colorado potato beetle adults and these resistant clones (Chapter 5). Adult longevity and fitness were studied for the first 3 weeks after emergence. The reproductive biology of the beetle on highly resistant clones, partly resistant clones and control potato plants was monitored by dissecting females after 7-15 days of feeding and by analyzing the haemolymph's protein content after 3 days of feeding. Feeding behavior on either highly toxin expressing or control plants was monitored individually for 36 beetles feeding on leaf-discs. Beetles feeding on transgenic or control clones as the sole source of food had similar longevity. However egg production was completely inhibited on transgenic plants.Dissection studies indicated that adult males living on transgenic plants were still able to mate and produce mobile sperms, but the females were impaired in their reproductive ability since ovarioles were not normally developed. An exam of the haemolymph revealed the protein concentration in females living on transgenic plants to be dramatically reduced (about 50% compared to the control). The feeding behavior of Colorado potato beetle adults was not affected by the different food plants. This shows that transgenic potato plants were readily accepted as host plants by the beetles. The implications of these findings for the use of transgenic plants as a means of L. decemlineata control are discussed.In the sixth chapter the most relevant results of the first year of a field experiment with the transgenic eggplant lines are presented. Two of the 3 transgenic lines used showed a high level of resistance in two separate trials, as indicated by the analyses of L. decemlineata population levels and crop yield. Fruit production was almost doubled in the resistant lines compared to a DR2 untransformed control. Only one transgenic line showed an intermediate level of resistance, giving results more similar to the control under heavy CPB attack, whereas it gave comparable results to the other transgenic lines where natural infestation was milder. No detrimental effects on non-target arthropods (including the chrysomelid beetle Altica spp.) were apparent. Field observations confirmed that Bt-expressing transgenic plants might be able to successfully control Colorado potato beetle infestations in eggplant cultivations, representing a potentially effective and environmentally safe means of pest control.In chapter 7, the relationships between L. decemlineata egg density and Coleomegillamaculata DeGeer predatory behavior is presented. Despite aggregation in areas of the highest prey density by C.maculata , egg consumption was inversely related to egg mass density at the smallest and the largest spatial scales tested. The experimental data on predation rates in high and low density field treatments, were included in a mathematical model to simulate the impact of natural enemies on the rate of L.decemlineata adaptation to Bt-toxin-expressing transgenic potato plants when Bt-expressing plants are mixed at the plot-to-plot level with normal potato plants. Results showed that C.maculata predatory behavior could decrease the rate at which L.decemlineata adapted to Bt-toxins if plot-to-plot mixed plantings were used.Finally, a simulation model to predict the possible adaptation of L. decemlineata to the Cry3 toxin expressed in transgenic eggplant is presented (Chapter 8). The use of mixed fields of transgenic and susceptible isolines at a 90:10 ratio has been simulated. Beetle movement, which is a fundamental parameter when studying plant mixtures, has been addressed with a 'two-stage' hypothesis. The biological and genetic characteristics of the beetles have been set to specifically address their possible interactions with resistant eggplant. The role of gene dominance, migration, and fitness costs associated with the resistant genotype have been examined. Using the hypothesis of partial dominance of the resistant gene, only a high level of migration (very likely, in most agricultural areas) or a considerable reduction of the fitness of resistant beetles, associated with the change in their genome, can guarantee a long-lasting efficacy of the germplasm. The simulations clearly indicate that the effect of resistance in transgenic clones expressing Bacillus thuringiensis -derived toxins can be optimized only in accordance with opportune agricultural practices.</p

Influence of Topological Edge States on the Properties of Al/Bi2Se3/Al Hybrid Josephson Devices

In superconductor-topological insulator-superconductor hybrid junctions, the barrier edge states are expected to be protected against backscattering, to generate unconventional proximity effects, and, possibly, to signal the presence of Majorana fermions. The standards of proximity modes for these types of structures have to be settled for a neat identification of possible new entities. Through a systematic and complete set of measurements of the Josephson properties we find evidence of ballistic transport in coplanar Al-Bi2Se3-Al junctions that we attribute to a coherent transport through the topological edge state. The shunting effect of the bulk only influences the normal transport. This behavior, which can be considered to some extent universal, is fairly independent of the specific features of superconducting electrodes. A comparative study of Shubnikov - de Haas oscillations and Scanning Tunneling Spectroscopy gave an experimental signature compatible with a two dimensional electron transport channel with a Dirac dispersion relation. A reduction of the size of the Bi2Se3 flakes to the nanoscale is an unavoidable step to drive Josephson junctions in the proper regime to detect possible distinctive features of Majorana fermions.Comment: 11 pages, 14 figure

Preliminary impedance spectroscopy study for carious lesions detection

This preliminary study proposes the use of impedance spectroscopy as additional diagnostic method in clinical practice to assess carious lesions. The carious process leads to a characteristic loss of mineral and a subsequent increased porosity, which results in a higher liquid content than sound tissue. The absorbed liquid contains different ions coming from the oral environment which, together with the increased porosity, contribute to change the impedance of the tissue. Impedance measurement is able to detect such tissue modifications and, therefore, it can be a suitable approach for assessing the presence and the status of carious processes on teeth. Moreover, compared to other diagnostic techniques it is more promising, also for the development of in-vivo measurements, owing to its safety, reliability, simplicity, rapid response, cost-effective, robust, and adequate detection limit. This study compares impedance spectroscopy measurements collected by using two different types of probes for monitoring teeth with and without carious lesions. The authors used a Ni-Cr wire electrode with a diameter of 0.5 mm, and a hydrogel agar probe with a diameter of 5 mm. Impedance measurements were carried out in-vitro by means of the Ivium-n-Stat potentiostat with a two-electrode setup, on the occlusal surfaces of teeth with and without carious lesions; then, the impedance spectra were recorded and analyzed. The preliminary results highlight that both experimental probes allow detecting a shift in impedance phase spectra, which happens at different frequencies and can be correlated to healthy teeth and the carious lesions, respectively

Robotic Autism Rehabilitation by Wearable Brain-Computer Interface and Augmented Reality

An instrument based on the integration of Brain Computer Interface (BCI) and Augmented Reality (AR) is proposed for robotic autism rehabilitation. Flickering stimuli at fixed frequencies appear on the display of Augmented Reality (AR) glasses. When the user focuses on one of the stimuli a Steady State Visual Evoked Potentials (SSVEP) occurs on his occipital region. A single-channel electroencephalographic Brain Computer Interface detects the elicited SSVEP and sends the corresponding commands to a mobile robot. The device's high wearability (single channel and dry electrodes), and the trainingless usability are fundamental for the acceptance by Autism Spectrum Disorder (ASD) children. Effectively controlling the movements of a robot through a new channel enhances rehabilitation engagement and effectiveness. A case study at an accredited rehabilitation center on 10 healthy adult subjects highlighted an average accuracy higher than 83%. Preliminary further tests at the Department of Translational Medical Sciences of University of Naples Federico II on 3 ASD patients between 8 and 10 years old provided positive feedback on device acceptance and attentional performance

Composition of arthropod species assemblages in Bt-expressing and near isogenic eggplants in experimental fields

The environmental impact of genetically modified (GM) plants in experimental fields has been examined in several ways, in particular with respect to the dynamics of specific nontarget organisms. The approach of sampling for biodiversity in agroecosystems to compare complex patterns could also be useful in studying potential disruptions caused by GM crops. In this study, we set up replicated field plots of Bt-expressing eggplants and near isogenic untransformed eggplants as a control. We monitored the presence and abundance of herbivore and predator arthropods in weekly visual samplings of the plant canopy for three growing seasons (2001-2003). Insect species were pooled in organismal taxonomic units (OTUs); three multivariate methods were used to compare species assemblage as an estimate of insect biodiversity. This multistep statistical approach proved to be efficient in recognizing association patterns, as evidenced by the data for the target species Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae) clearly showing a significant association with the control plots. All the analyses indicate a comparable species assemblage between transgenic and near isogenic eggplant areas. Our results suggest that some taxa may warrant more specific study. For example, Alticinae beetles (Coleoptera: Chrysomelidae) were alternatively more abundant in either of the two treatments, and their overall abundance was significantly higher on transgenic eggplants. In light of these results and because of their taxonomic proximity to the target species, these herbivores may represent an important nontarget group to be further studied. Moreover, some sap feeders (e.g., Homoptera: Cicadellidae) were more abundant on Bt-expressing plants in some samples in all 3 yr

Enhancement of SSVEPs Classification in BCI-based Wearable Instrumentation Through Machine Learning Techniques

This work addresses the adoption of Machine Learning classifiers and Convolutional Neural Networks to improve the performance of highly wearable, single-channel instrumentation for Brain-Computer Interfaces. The proposed measurement system is based on the classification of Steady-State Visually Evoked Potentials (SSVEPs). In particular, Head-Mounted Displays for Augmented Reality are used to generate and display the flickering stimuli for the SSVEPs elicitation. Four experiments were conducted by employing, in turn, a different Head-Mounted Display. For each experiment, two different algorithms were applied and compared with the state-of-the-art-techniques. Furthermore, the impact of different Augmented Reality technologies in the elicitation and classification of SSVEPs was also explored. The experimental metrological characterization demonstrates (i) that the proposed Machine Learning-based processing strategies provide a significant enhancement of the SSVEP classification accuracy with respect to the state of the art, and (ii) that choosing an adequate Head-Mounted Display is crucial to obtain acceptable performance. Finally, it is also shown that the adoption of inter-subjective validation strategies such as the Leave-One-Subject-Out Cross Validation successfully leads to an increase in the inter-individual 1-σ reproducibility: this, in turn, anticipates an easier development of ready-to-use systems

Editorial: Advances and Challenges of RNAi Based Technologies for Plants—Volume 2

Editorial on the Research Topic: Advances and Challenges of RNAi Based Technologies for Plants—Volume