7,208 research outputs found
The distance to the Galactic centre based on Population II Cepheids and RR Lyrae stars
No full textContext. The distance to the Galactic centre (GC) is important
for determining the distance scale in the Universe. The value derived by
Eisenhauer et al. (2005) of 7.62 ± 0.32 kpc based on the orbit of
one star around the central black hole is shorter than most other
distance estimates based on a variety of different methods.
Aims. To establish an independent distance to the GC with high accuracy,
Population-i
Meditation Awareness Training (MAT) for work-related wellbeing and job performance: a randomised controlled trial
No full textDue to its potential to concurrently improve work-related wellbeing (WRW) and job performance, occupational stakeholders are becoming increasingly interested in the applications of meditation. The present study conducted the first randomized controlled trial to assess the effects of meditation on outcomes relating to both WRW and job performance. Office-based middle-hierarchy managers (n = 152) received an eight-week meditation intervention (Meditation Awareness Training; MAT) or an active control intervention. MAT participants demonstrated significant and sustainable improvements (with strong effect sizes) over control-group participants in levels of work-related stress, job satisfaction, psychological distress, and employer-rated job performance. There are a number of novel implications: (i) meditation can effectuate a perceptual shift in how employees experience their work and psychological environment and may thus constitute a cost-effective WRW intervention, (ii) meditation-based (i.e., present-moment-focussed) working styles may be more effective than goal-based (i.e., future-orientated) working styles, and (iii) meditation may reduce the separation made by employees between their own interests and those of the organizations they work for
Voorlopige resultaten proeven Zinkcon mat
No full textResultaten proeven met de Zinkcon mat in de stroomgoot in Lith op ware grootte.KWP-collectio
Applying the method of fundamental solutions to harmonic problems with singular boundary conditions
No full textThe method of fundamental solutions (MFS) is known to produce highly accurate numerical results for elliptic boundary value problems (BVP) with smooth boundary conditions, posed in analytic domains. However, due to the analyticity of the shape
functions in its approximation basis, theMFS is usually disregarded when the boundary functions possess singularities. In this work we present a modification of the classical MFS which can be applied for the numerical solution of the Laplace BVP with Dirichlet boundary conditions exhibiting jump discontinuities. In particular, a set of harmonic functions with discontinuous boundary traces is added to the MFS basis. The accuracy of the proposed method is compared with the results form the classical MFS.The financial support from Center for Computational and Stochastic Mathematics (CEMAT–IST) through Fundac¸ ˜ao para a Ciˆencia e a Tecnologia (FCT) projects PEst-OE/MAT/UI0822/2014 and EXCL/MAT-NAN/0114/2012 is gratefully acknowledged
Evolution of asymptotic giant branch stars - II. Optical to far-infrared isochrones with improved TP-AGB models
No full textWe present a large set of theoretical isochrones, whose distinctive features mostly reside on the greatly-improved treatment of the thermally-pulsing asymptotic giant branch (TP-AGB) phase. Essentially, we have coupled the TP-AGB tracks described in Paper I, at their stages of pre-flash quiescent H-shell burning, with the evolutionary tracks for the previous evolutionary phases from Girardi et al. (2000, A&AS, 141, 371). Theoretical isochrones for any intermediate value of age and metallicity are then derived by interpolation in the grids. We take care that the isochrones keep, to a good level of detail, the several peculiarities present in these TP-AGB tracks - e.g., the cool tails of C-type stars owing to the use of proper molecular opacities as convective dredge-up occurs along the TP-AGB; the bell-shaped sequences in the Hertzsprung-Russell (HR) diagram for stars with hot-bottom burning; the changes of pulsation mode between fundamental and first overtone; the sudden changes of mean mass-loss rates as the surface chemistry changes from M- to C-type; etc. Theoretical isochrones are then converted to about 20 different photometric systems - including traditional ground-based systems, and those of recent major wide-field surveys such as SDSS, OGLE, DENIS, 2MASS, UKIDSS, etc., - by means of synthetic photometry applied to an updated library of stellar spectra, suitably extended to include C-type stars. Finally, we correct the predicted photometry for the effect of circumstellar dust during the mass-losing stages of the AGB evolution, which allows us to improve the results for the optical-to-infrared systems, and to simulate mid- and far-IR systems such as those of Spitzer and AKARI. We illustrate the most striking properties of these isochrones by means of basic comparisons with observational data for the Milky Way disc and the Magellanic Clouds. Access to the data is provided both via a web repository of static tables (http://stev.oapd.inaf.it/dustyAGB07 and CDS), and via an interactive web interface (http://stev.oapd.inaf.it/cmd), which provides tables for any intermediate value of age and metallicity, for several photometric systems, and for different choices of dust properties
Fotoreportage Samenstellen van de mat voor de grote legproef II
No full textFoto’s van het maken van een proefmat (gaasmat verschillende lagen met filtermateriaal), het oprollen van de mat; bij de fabriek in Kats
The proposed goodyear modular mat type scrap tire floating breakwater
No full textScrap tires are proposed as a construction material for building large floating mat type breakwater devices. The Goodyear scrap tire floating breakwater assemblies are formed by securing together modular bundles of tightly interlocked scrap tires with high strength rope/cable, or special corrosion resistant steel rods. This construction procedure yields an easily installed, readily adaptable breakwater structure which has high energy absorbing capacity for normal loading conditions but which deforms and yields when subjected to overloads. The proposed designs rely on a modular bundle concept where a relatively few tires are secured together to form a small easily assemble de portable building unit which,serves as a basic building block from which giant breakwater devices can be constructed. Flotation is provided by placing a small amount of buoyant material in the crown of each tire or by filling approximately 10%) of the tires with buoyant foam. The design possibilities using scrap tire building modules are virtually limiless. Tires may be laced together to form large flat single or multiple thickness shallow mats. They may be stacked vertically in single or multiple thickness bundles like bricks in a wall to form curtain type barriers. Variutions in breakwater draft are made possible by adding modules above or below to vary the thickness and by combining constructions such as hanging a curtain on a mat structure. Also, mats with varying buoyancy may be moored on an incline for more efficient energy absorption
Application of MAT device to characterize the adhesive bonding strength of membrane in orthotropic steel deck bridges
No full textIn order to characterize adequately the adhesive bonding strength of the various membranes with surrounding materials on orthotropic steel decks and collect the necessary parameters for FE modeling, details of the Membrane Adhesion Test (MAT) have been introduced. Analytical constitutive relations of MAT device have been derived on the basis of Williams (1997). Furthermore, on the basis of experimental data obtained from MAT, ranking of the bonding characteristics of various membrane products is demonstrated as well as the role of other influencing factors, such as the types of substrate and test temperatures.Structural EngineeringCivil Engineering and Geoscience
Tail dependence under sample failures
No full textWhen collecting samples, sometimes failures of observations occur and consequently missing data. This can have an impact on the analysis and subsequent inference, especially if the study focuses on the extreme values where the data is more scarce. In this work, we analyze the effect of different types of failures on the dependence within the tail of a stationary series. We will also present some examples.The first author was supported by Portuguese Funds through FCT — Fundação para a Ciência e a Tecnologia within the Projects UID/MAT/00013/2013 of Centre of Mathematics of the University of Minho, UID/Multi/04621/2019 of Center for Computational and Stochastic Mathematics, UID/MAT/00006/2019 of Centre of Statistics and Its Applications, and PTDC/MAT-STA/28243/2017. The second author was partially supported by the research unit UID/MAT/00212/2019 — FCT (Funda¸c˜ao para a Ciˆencia e a Tecnologia)
Neural Networks to Predict Financial Time Series in a Minority Game Context
No full textIn this paper we consider financial time series from U.S. Fixed Income Market, S&P500, Exchange Market and Oil Market. It is well known that financial time series reveal some anomalies as regards the Efficient Market Hypotesis and some scaling behavior is evident such as fat tails and clustered volatility. This suggests to consider financial time serie as "pseudo"-random time series. For this kind of time series the power of prediction of neural networks has been shown to be appreciable. We first consider the financial time serie from the Minority Game point of view and than we apply a neural network with learning algorithm in order to analyze its prediction power. We show that Fixed Income Market presents many differences from other markets in terms of predictability as a measure of market efficiency.Minority Game, Learning Algorithms, Neural Networks, Financial Time Series, Efficient Market Hypotesis
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