Infrared light emission from atomic point contacts

Gold atomic point contacts are prototype systems to evidence ballistic electron transport. The typical dimension of the nanojunction being smaller than the electron-phonon interaction length, even at room temperature, electrons transfer their excess energy to the lattice only far from the contact. At the contact however, favored by huge current densities, electron-electron interactions result in a nano hot electron gas acting as a source of photons. Using a home built Mechanically Controlled Break Junction, it is reported here, for the first time, that this hot electron gas also radiates in the infrared range (0.2eV to 1.2eV). Moreover, in agreement with the pioneering work of Tomchuk, we show that this radiation is compatible with a blackbody like spectrum emitted from an electron gas at temperatures of several thousands of Kelvin given by $(kB.Te)^2 = \alpha. I.V$ where $\alpha$, $I$ and $V$ are respectively a fitting parameter, the current flowing and the applied bias.Comment: 13 pages, 5 figure

Estimating single molecule conductance from spontaneous evolution of a molecular contact

We present an original method to estimate the conductivity of a single molecule anchored to nanometric-sized metallic electrodes, using a Mechanically Controlled Break Junction (MCBJ) operated at room temperature in liquid. We record the conductance through the metal / molecules / metal nanocontact while keeping the metallic electrodes at a fixed distance. Taking advantage of thermal diffusion and electromigration, we let the contact naturally explore the more stable configurations around a chosen conductance value. The conductance of a single molecule is estimated from a statistical analysis of raw conductance and conductance standard deviation data for molecular contacts containing up to 14 molecules. The single molecule conductance values are interpreted as time-averaged conductance of an ensemble of conformers at thermal equilibrium.Comment: 25 pages, 6 figure

Spending time with money: from shared values to social connectivity

This article has been made available through the Brunel Open Access Publishing Fund.There is a rapidly growing momentum driving the development of mobile payment systems for co-present interactions, using near-field communication on smartphones and contactless payment systems. The design (and marketing) imperative for this is to enable faster, simpler, effortless and secure transactions, yet our evidence shows that this focus on reducing transactional friction may ignore other important features around making payments. We draw from empirical data to consider user interactions around financial exchanges made on mobile phones. Our findings examine how the practices around making payments support people in making connections, to other people, to their communities, to the places they move through, to their environment, and to what they consume. While these social and community bonds shape the kinds of interactions that become possible, they also shape how users feel about, and act on, the values that they hold with their co-users. We draw implications for future payment systems that make use of community connections, build trust, leverage transactional latency, and generate opportunities for rich social interactions

Room temperature spin relaxation in GaAs/AlGaAs multiple quantum wells

We have explored the dependence of electron spin relaxation in undoped GaAs/AlGaAs quantum wells on well width (confinement energy) at 300 K. For wide wells, the relaxation rate tends to the intrinsic bulk value due to the D'yakonov-Perel (DP) mechanism with momentum scattering by phonons. In narrower wells, there is a strong dependence of relaxation rate on well width, as expected for the DP mechanism, but also considerable variation between samples from different sources, which we attribute to differences in sample interface morphology. (C) 1998 American Institute of Physics. [S0003-6951(98)02541-8].</p

Cost effective flat plate photovoltaic modules using light trapping

Work in optical trapping in 'thick films' is described to form a design guide for photovoltaic engineers. A thick optical film can trap light by diffusive reflection and total internal reflection. Light can be propagated reasonably long distances compared with layer thicknesses by this technique. This makes it possible to conduct light from inter-cell and intra-cell areas now not used in photovoltaic modules onto active cell areas

R23. Demographics and Outcomes of Patients Hospitalized for COVID-19

Corresponding author (University of Mississippi Medical Center): Jonathan T. Newbaker, [email protected]://egrove.olemiss.edu/pharm_annual_posters/1022/thumbnail.jp

Meta-awareness during day and night: the relationship between mindfulness and lucid dreaming.

The present study explored the relationship between lucidity in dreams (awareness of dreams while dreaming) and mindfulness during wakefulness, also considering meditation as a possible moderating variable. An online survey was completed by 528 respondents, of whom 386 (73.1%) had lucid dream experiences. The reported frequency of lucid dreams was found to be positively related to higher dispositional mindfulness in wakefulness. This relationship was only present in those participants who reported acquaintance with meditation. Regarding the dimensions of mindfulness, lucid dream frequency was more strongly associated with mindful presence rather than acceptance. The findings support the notion of an existing relationship between lucidity in dreams and mindfulness during wakefulness, yet it remains unclear whether the relationship is influenced by actual meditation practice or whether it reflects some natural predispositions. Future studies should examine the role of different meditation practices, investigate personality variables that might influence the relationship, and explore how different facets of mindfulness and lucidity interrelate. Keywords: lucid dreaming; mindfulness; meditatio

A phased array-based method for damage detection and localization in thin plates

A method for damage localization based on the phased array idea has been developed. Four arrays oftransducers are used to perform a beam-forming procedure. Each array consists of nine transducersplaced along a line, which are able to excite and register elastic waves. The A0 Lamb wave mode hasbeen chosen for the localization method. The arrays are placed in such a way that the angulardifference between them is 458 and the rotation point is the middle transducer, which is common for allthe arrays. The idea has been tested on a square aluminium plate modeled by the Spectral Element Method. Two types of damage were considered, namely distributed damage, which was modeled asstiffness reduction, and cracks, modeled as separation of nodes between selected spectral elements.The plate is excited by a wave packet. The whole array system is placed in the middle of the plate.Each linear phased array in the system acts independently and produces maps of a scanned fieldbased on the beam-forming procedure. These maps are made of time signals (transferred to spacedomain) that represent the difference between the damaged plate signals and those from the intactplate. An algorithm was developed to join all four maps. The final map is modified by proposed signal processing algorithm to indicate the damaged area of the plate more precisely. The problem fordamage localization was investigated and exemplary maps confirming the effectiveness of theproposed system were obtained. It was also shown that the response of the introduced configurationremoves the ambiguity of damage localization normally present when a linear phased array is utilized.The investigation is based exclusively on numerical data

Learning Visual Question Answering by Bootstrapping Hard Attention

Attention mechanisms in biological perception are thought to select subsets of perceptual information for more sophisticated processing which would be prohibitive to perform on all sensory inputs. In computer vision, however, there has been relatively little exploration of hard attention, where some information is selectively ignored, in spite of the success of soft attention, where information is re-weighted and aggregated, but never filtered out. Here, we introduce a new approach for hard attention and find it achieves very competitive performance on a recently-released visual question answering datasets, equalling and in some cases surpassing similar soft attention architectures while entirely ignoring some features. Even though the hard attention mechanism is thought to be non-differentiable, we found that the feature magnitudes correlate with semantic relevance, and provide a useful signal for our mechanism's attentional selection criterion. Because hard attention selects important features of the input information, it can also be more efficient than analogous soft attention mechanisms. This is especially important for recent approaches that use non-local pairwise operations, whereby computational and memory costs are quadratic in the size of the set of features.Comment: ECCV 201