Possible indicators for low dimensional superconductivity in the quasi-1D carbide Sc3CoC4

The transition metal carbide Sc3CoC4 consists of a quasi-one-dimensional (1D) structure with [CoC4]_{\inft} polyanionic chains embedded in a scandium matrix. At ambient temperatures Sc3CoC4 displays metallic behavior. At lower temperatures, however, charge density wave formation has been observed around 143K which is followed by a structural phase transition at 72K. Below T^onset_c = 4.5K the polycrystalline sample becomes superconductive. From Hc1(0) and Hc2(0) values we could estimate the London penetration depth ({\lambda}_L ~= 9750 Angstroem) and the Ginsburg-Landau (GL) coherence length ({\xi}_GL ~= 187 Angstroem). The resulting GL-parameter ({\kappa} ~= 52) classifies Sc3CoC4 as a type II superconductor. Here we compare the puzzling superconducting features of Sc3CoC4, such as the unusual temperature dependence i) of the specific heat anomaly and ii) of the upper critical field H_c2(T) at T_c, and iii) the magnetic hysteresis curve, with various related low dimensional superconductors: e.g., the quasi-1D superconductor (SN)_x or the 2D transition-metal dichalcogenides. Our results identify Sc3CoC4 as a new candidate for a quasi-1D superconductor.Comment: 4 pages, 5 figure

Ordinal patterns in epileptic brains: Analysis of intracranial EEG and simultaneous EEG-fMRI

Epileptic seizures are associated with high behavioral stereotypy of the patients. In the EEG of epilepsy patients characteristic signal patterns can be found during and between seizures. Here we use ordinal patterns to analyze EEGs of epilepsy patients and quantify the degree of signal determinism. Besides relative signal redundancy and the fraction of forbidden patterns we introduce the fraction of under-represented patterns as a new measure. Using the logistic map, parameter scans are performed to explore the sensitivity of the measures to signal determinism. Thereafter, application is made to two types of EEGs recorded in two epilepsy patients. Intracranial EEG shows pronounced determinism peaks during seizures. Finally, we demonstrate that ordinal patterns may be useful for improving analysis of non-invasive simultaneous EEG-fMR

Two-parameter characterization of crack-tip fields during thermal transients

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994.Includes bibliographical references (leaves 121-126).by Dagmar E. Hauf.M.S

Geant4-related R&D for new particle transport methods

A R&D project has been launched in 2009 to address fundamental methods in radiation transport simulation and revisit Geant4 kernel design to cope with new experimental requirements. The project focuses on simulation at different scales in the same experimental environment: this set of problems requires new methods across the current boundaries of condensed-random-walk and discrete transport schemes. An exploration is also foreseen about exploiting and extending already existing Geant4 features to apply Monte Carlo and deterministic transport methods in the same simulation environment. An overview of this new R&D associated with Geant4 is presented, together with the first developments in progress.Comment: 4 pages, to appear in proceedings of the Nuclear Science Symposium and Medical Imaging Conference 2009, Orland

Learning tethered perching for aerial robots

Aerial robots have a wide range of applications, such as collecting data in hard-to-reach areas. This requires the longest possible operation time. However, because currently available commercial batteries have limited specific energy of roughly 300 W h kg -1 , a drone's flight time is a bottleneck for sustainable long-term data collection. Inspired by birds in nature, a possible approach to tackle this challenge is to perch drones on trees, and environmental or man-made structures, to save energy whilst in operation. In this paper, we propose an algorithm to automatically generate trajectories for a drone to perch on a tree branch, using the proposed tethered perching mechanism with a pendulum-like structure. This enables a drone to perform an energy-optimised, controlled 180° flip to safely disarm upside down. To fine-tune a set of reachable trajectories, a soft actor critic-based reinforcement algorithm is used. Our experimental results show the feasibility of the set of trajectories with successful perching. Our findings demonstrate that the proposed approach enables energy-efficient landing for long-term data collection tasks

A case study of boundary layer ventilation by convection and coastal processes

It is often assumed that ventilation of the atmospheric boundary layer is weak in the absence of fronts, but is this always true? In this paper we investigate the processes responsible for ventilation of the atmospheric boundary layer during a nonfrontal day that occurred on 9 May 2005 using the UK Met Office Unified Model. Pollution sources are represented by the constant emission of a passive tracer everywhere over land. The ventilation processes observed include shallow convection, turbulent mixing followed by large-scale ascent, a sea breeze circulation and coastal outflow. Vertical distributions of tracer are validated qualitatively with AMPEP (Aircraft Measurement of chemical Processing Export fluxes of Pollutants over the UK) CO aircraft measurements and are shown to agree impressively well. Budget calculations of tracers are performed in order to determine the relative importance of these ventilation processes. Coastal outflow and the sea breeze circulation were found to ventilate 26% of the boundary layer tracer by sunset of which 2% was above 2 km. A combination of coastal outflow, the sea breeze circulation, turbulent mixing and large-scale ascent ventilated 46% of the boundary layer tracer, of which 10% was above 2 km. Finally, coastal outflow, the sea breeze circulation, turbulent mixing, large-scale ascent and shallow convection together ventilated 52% of the tracer into the free troposphere, of which 26% was above 2 km. Hence this study shows that significant ventilation of the boundary layer can occur in the absence of fronts (and thus during high-pressure events). Turbulent mixing and convection processes can double the amount of pollution ventilated from the boundary layer

Towards a new philological edition of Vincent Ferrer’s Lenten sermons (València, 1413): a specimen

L’article presenta una nova edició fi lològica, actualment en preparació, dels cinquanta-tres sermons de quaresma predicats l’any 1413 a València per Vicent Ferrer (València, Arxiu de la Catedral, ms. 273). Després d’una breu introducció en què s’aborden les raons que justifi quen una nova edició d’aquest sermonari, s’ofereix una mostra del text crític, acompanyat d’un aparat textual i de notes explicatives.This paper showcases an ongoing new philological edition of Vincent Ferrer’s fi fty-three Lenten sermons preached in València in 1413 (València, Cathedral Archive, ms. 273). A short introduction that gives the rationale for a new edition of this sermonary is followed by a sample of the critical text, supplemented by a textual apparatus and explanatory notes