Modelling diffuse instabilities in sands under drained conditions

This paper presents a criterion for detecting diffuse (homogeneous) instabilities in granular soils sheared under fully drained conditions. The criterion is based on bifurcation theory and applied to elasto-plasticity by allowing multiple incremental solutions in elasto-plastic soils, physically losing controllability of stress boundary conditions. Drained diffuse instabilities are poorly understood, and are induced by kinematic modes different from those observed in shear bands and liquefaction instabilities. Unlike shear bands, diffuse instabilities occur under fairly homogenous deformation modes and, unlike liquefaction, drained instabilities are not generated by the excess pore pressures. Recent experiments under drained constant shear report sudden homogeneous instabilities in samples of relatively dense and loose sands. The criterion presented in this paper is used in conjunction with an elasto-plasticity model for sands to predict and explain these reported drained instabilities. From a practical standpoint, these developments serve to expand the repertoire of potential instabilities that occur well before failure, and which have been reported in case studies of puzzling slope instability failures under fully drained conditions

Neutron Transfer reactions induced by 8Li on 9Be

Angular distributions for the elastic scattering of 8Li on 9Be and the neutron transfer reactions 9Be(8Li,7Li)10Be and 9Be(8Li,9Li)8Be have been measured with a 27 MeV 8Li radioactive nuclear beam. Spectroscopic factors for 8Li|n=9Li and 7Li|n=8Li bound systems were obtained from the comparison between the experimental differential cross section and finite-range DWBA calculations with the code FRESCO. The spectroscopic factors obtained are compared to shell model calculations and to other experimental values from (d,p) reactions. Using the present values for the spectroscopic factor, cross sections for the direct neutron-capture reactions 7Li(n,g)8Li and 8Li(n,g)9Li were calculated in the framework of a potential model.Comment: 24 pages, 8 Figures, submitted as regular article to PR

Modelling Gherkin Scenarios Using UML

Gherkin scenarios are examples of the behavior of the system under development. They maybe part of the requirement specification, they may be part of the test suite and they are an excellenttool for gathering information among stakeholders, testers and developers. However,little work have been done formalizing Gherkin scenarios and modelling them as part of UMLdiagrams. This paper introduces an abstract syntax and concrete syntax for modeling Gherkinscenarios in UML Use Case diagrams. This paper also introduces a tool for running Gherkinscenarios from UML Use Case diagrams as test case

Speech-to-Speech synchronization protocol to classify human participants as high or low auditory-motor synchronizers

The ability to synchronize a motor action to a rhythmic auditory stimulus is often considered an innate human skill. However, some individuals lack the ability to synchronize speech to a perceived syllabic rate. Here, we describe a simple and fast protocol to classify a single native English speaker as being or not being a speech synchronizer. This protocol consists of four parts: the pretest instructions and volume adjustment, the training procedure, the execution of the main task, and data analysis

Transfer/Breakup Modes in the 6He+209Bi Reaction Near and Below the Coulomb Barrier

Reaction products from the interaction of 6He with 209Bi have been measured at energies near the Coulomb barrier. A 4He group of remarkable intensity, which dominates the total reaction cross section, has been observed. The angular distribution of the group suggests that it results primarily from a direct nuclear process. It is likely that this transfer/breakup channel is the doorway state that accounts for the previously observed large sub-barrier fusion enhancement in this system.Comment: 4 pages; 3 figure

The LKB1-salt-inducible kinase pathway functions as a key gluconeogenic suppressor in the liver

LKB1 is a master kinase that regulates metabolism and growth through adenosine monophosphate-activated protein kinase (AMPK) and 12 other closely related kinases. Liver-specific ablation of LKB1 causes increased glucose production in hepatocytes in vitro and hyperglycaemia in fasting mice in vivo. Here we report that the salt-inducible kinases (SIK1, 2 and 3), members of the AMPK-related kinase family, play a key role as gluconeogenic suppressors downstream of LKB1 in the liver. The selective SIK inhibitor HG-9-91-01 promotes dephosphorylation of transcriptional co-activators CRTC2/3 resulting in enhanced gluconeogenic gene expression and glucose production in hepatocytes, an effect that is abolished when an HG-9-91-01-insensitive mutant SIK is introduced or LKB1 is ablated. Although SIK2 was proposed as a key regulator of insulin-mediated suppression of gluconeogenesis, we provide genetic evidence that liver-specific ablation of SIK2 alone has no effect on gluconeogenesis and insulin does not modulate SIK2 phosphorylation or activity. Collectively, we demonstrate that the LKB1-SIK pathway functions as a key gluconeogenic gatekeeper in the liver

Links between topography, wind, deflation, lakes and dust: The case of the Bodélé Depression, Chad

The Bodélé Depression, Chad is the planet's largest single source of dust. Deflation from the Bodélé could be seen as a simple coincidence of two key prerequisites: strong surface winds and a large source of suitable sediment. But here we hypothesise that long term links between topography, winds, deflation and dust ensure the maintenance of the dust source such that these two apparently coincidental key ingredients are connected by land-atmosphere processes with topography acting as the overall controlling agent. We use a variety of observational and numerical techniques, including a regional climate model, to show that: 1) contemporary deflation from the Bodélé is delineated by topography and a surface wind stress maximum; 2) the Tibesti and Ennedi mountains play a key role in the generation of the erosive winds in the form of the Bodélé Low Level Jet (LLJ); 3) enhanced deflation from a stronger Bodélé LLJ during drier phases, for example, the Last Glacial Maximum, was probably sufficient to create the shallow lake in which diatoms lived during wetter phases, such as the Holocene pluvial. Winds may therefore have helped to create the depression in which erodible diatom material accumulated. Instead of a simple coincidence of nature, dust from the world's largest source may result from the operation of long term processes on paleo timescales which have led to ideal conditions for dust generation in the world's largest dust source. Similar processes plausibly operate in other dust hotspots in topographic depressions

From Lab to Production: Lessons Learnt and Real-Life Challenges of an Early Student-Dropout Prevention System

This paper presents the work done to support student dropout risk prevention in a real online e-learning environment: A Spanish distance university with thousands of undergraduate students. The main goal is to prevent students from abandoning the university by means of retention actions focused on the most at-risk students, trying to maximize the effectiveness of institutional efforts in this direction. With this purpose, we generated predictive models based on the C5.0 algorithm using data from more than 11,000 students collected along five years. Then we developed SPA, an early warning system that uses these models to generate static early dropout-risk predictions and dynamic periodically updated ones. It also supports the recording of the resulting retention-oriented interventions for further analysis. SPA is in production since 2017 and is currently in its fourth semester of continuous use. It has calculated more than 117,000 risk scores to predict the dropout risk of more than 5,700 students. About 13,000 retention actions have been recorded. The white-box predictive models used in production provided reasonably good results, very close to those obtained in the laboratory. On the way from research to production, we faced several challenges that needed to be effectively addressed in order to be successful. In this paper, we share the challenges faced and the lessons learnt during this process. We hope this helps those who wish to cross the road from predictive modelling with potential value to the exploitation of complete dropout prevention systems that provide sustained value in real production scenarios2018-201