Raman Scattering and Lattice-Dynamical Calculations of Crystalline KNO\u3csub\u3e3\u3c/sub\u3e

The Raman spectrum of a KNO3 single crystal was measured at both room and liquid-nitrogen temperatures. Lattice-dynamical calculations, based on the rigid-ion approximation and empirical potentials, were performed. The possibility of a phase transition at 217 K was investigated by measuring the temperature dependence of the Raman spectrum

Mixed Linear Layouts of Planar Graphs

A $k$-stack (respectively, $k$-queue) layout of a graph consists of a total order of the vertices, and a partition of the edges into $k$ sets of non-crossing (non-nested) edges with respect to the vertex ordering. In 1992, Heath and Rosenberg conjectured that every planar graph admits a mixed $1$-stack $1$-queue layout in which every edge is assigned to a stack or to a queue that use a common vertex ordering. We disprove this conjecture by providing a planar graph that does not have such a mixed layout. In addition, we study mixed layouts of graph subdivisions, and show that every planar graph has a mixed subdivision with one division vertex per edge.Comment: Appears in the Proceedings of the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017

Monte Carlo simulation of a mammographic test phantom

A test phantom, including a wide range of mammographic tissue equivalent materials and test details, was imaged on a digital mammographic system. In order to quantify the effect of scatter on the contrast obtained for the test details, calculations of the scatter-to-primary ratio (S/P) have been made using a Monte Carlo simulation of the digital mammographic imaging chain, grid and test phantom. The results show that the S/P values corresponding to the imaging conditions used were in the range 0.084-0.126. Calculated and measured pixel values in different regions of the image were compared as a validation of the model and showed excellent agreement. The results indicate the potential of Monte Carlo methods in the image quality-patient dose process optimisation, especially in the assessment of imaging conditions not available on standard mammographic unit

The impact of sound field systems on learning and attention in elementary school classrooms

Purpose: An evaluation of the installation and use of sound field systems (SFS) was carried out to investigate their impact on teaching and learning in elementary school classrooms. Methods: The evaluation included acoustic surveys of classrooms, questionnaire surveys of students and teachers and experimental testing of students with and without the use of SFS. Students ’ perceptions of classroom environments and objective data evaluating change in performance on cognitive and academic assessments with amplification over a six month period are reported. Results: Teachers were positive about the use of SFS in improving children’s listening and attention to verbal instructions. Over time students in amplified classrooms did not differ from those in nonamplified classrooms in their reports of listening conditions, nor did their performance differ in measures of numeracy, reading or spelling. Use of SFS in the classrooms resulted in significantly larger gains in performance in the number of correct items on the nonverbal measure of speed of processing and the measure of listening comprehension. Analysis controlling for classroom acoustics indicated that students ’ listening comprehension score

Central-Peak-Soft-Mode, Coupling in Ferroelectric Gd\u3csub\u3e2\u3c/sub\u3e(MoO\u3csub\u3e4\u3c/sub\u3e)\u3csub\u3e3\u3c/sub\u3e

Transmission measurements on Gd2(MoO4)3 in the ( 5-50)-cm-1 region were performed with use of tunable backward-wave oscillator sources (5-30 cm\u3e-1) and a Fourier spectrometer (30-50 cm\u3e-1). The resulting dielectric spectra show an additional low-frequency dispersion which was fitted with a standard central-peak model. Its characteristic relaxation frequency is ~20 cm\u3e-1 and the coupling between the soft mode and central mode increases near the transition temperature. This model also accounts very well for the weak anomaly in the clamped permittivity Ec measured at 63 MHz. The same central mode was used to fit earlier Raman soft-mode spectra. All of these data were fitted with a three-coupled-mode model which revealed that the soft-mode spectrum consists of two strongly coupled bare modes: a higher-frequency mode which softens and carries the entire Raman strength and a lower-frequency mode which is hard (59 cm-1) and Raman inactive. Both of these modes are also coupled to the central mode and this coupling increases sharply near the transition. The relatively large width of the central mode indicates its intrinsic nature and suggests partial disorder near the transition

GUN: An Efficient Execution Strategy for Querying the Web of Data

International audienceLocal-As-View (LAV) mediators provide a uniform interface to a federation of heterogeneous data sources, attempting to execute queries against the federation. LAV mediators rely on query rewriters to translate mediator queries into equivalent queries on the federated data sources. The query rewriting problem in LAV mediators has shown to be NP-complete, and there may be an exponential number of rewritings, making unfeasible the execution or even generation of all the rewritings for some queries. The complexity of this problem can be particularly impacted when queries and data sources are described using SPARQL conjunctive queries, for which millions of rewritings could be generated. We aim at providing an efficient solution to the problem of executing LAV SPARQL query rewritings while the gathered answer is as complete as possible. We formulate the Result-Maximal k-Execution problem (ReMakE) as the problem of maximizing the query results obtained from the execution of only k rewritings. Additionally, a novel query execution strategy called GUN is proposed to solve the ReMakE problem. Our experimental evaluation demonstrates that GUN outperforms traditional techniques in terms of answer completeness and execution time

The Third sector in France and the Labour Market Policy

In France, like in other Western European countries, the third sector has been on a steady increase during the last decade as the results of the Johns Hopkins comparative project shows it. Today nonprofit organisations play also an increasing role in labour market policies. In a country with a corporatist welfare state, the access to the labour-market represents the key for social rights

Field Micrometeorological Measurements, Process-Level Studies and Modeling of Methane and Carbon Dioxide Fluxes in a Boreal Wetland Ecosystem

The main instrumentation platform consisted of eddy correlation sensors mounted on a scaffold tower at a height of 4.2 m above the peat surface. The sensors were attached to a boom assembly which could be rotated into the prevailing winds. The boom assembly was mounted on a movable sled which, when extended, allowed sensors to be up to 2 m away from the scaffolding structure to minimize flow distortion. When retracted, the sensors could easily be installed, serviced or rotated. An electronic level with linear actuators allowed the sensors to be remotely levelled once the sled was extended. Two instrument arrays were installed. A primary (fast-response) array consisted of a three-dimensional sonic anemometer, a methane sensor (tunable diode laser spectrometer), a carbon dioxide/water vapor sensor, a fine wire thermocouple and a backup one-dimensional sonic anemometer. The secondary array consisted of a one-dimensional sonic anemometer, a fine wire thermocouple and a Krypton hygrometer. Descriptions of these sensors may be found in other reports (e.g., Verma; Suyker and Verma). Slow-response sensors provided supporting measurements including mean air temperature and humidity, mean horizontal windspeed and direction, incoming and reflected solar radiation, net radiation, incoming and reflected photosynthetically active radiation (PAR), soil heat flux, peat temperature, water-table elevation and precipitation. A data acquisition system (consisting of an IBM compatible microcomputer, amplifiers and a 16 bit analog-to-digital converter), housed in a small trailer, was used to record the fast response signals. These signals were low-pass filtered (using 8-pole Butterworth active filters with a 12.5 Hz cutoff frequency) and sampled at 25 Hz. Slow-response signals were sampled every 5 s using a network of CR21X (Campbell Scientific, Inc., Logan Utah) data loggers installed in the fen. All signals were averaged over 30-minute periods (runs)

Raman scattering and lattice-dynamical calculations of alkali-metal sulfates

Raman-scattering measurements on single crystals of K2SO4, Rb2SO4, and Cs2SO4 have been made at both room and liquid-nitrogen temperatures. Lattice-dynamical calculations, based on a rigid-ion model using the Gordon-Kim method to calculate the short-range potentials, were performed. The influence of the alkali-metal ions on the lattice-dynamical properties of the crystals is discussed