355,618 research outputs found
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
Utilization of Palm-mat Geotextiles to Conserve Agricultural Soils.
Get PDFPreviously, most studies on the effectiveness of geotextiles on soil erosion rates and processes were conducted in laboratory experiments for <1 h. Hence, at Hilton (52o33' N, 2o19' W), East Shropshire, UK, we investigated the effectiveness of employing palm-mat geotextiles (Borassus and Buriti mats) to reduce rainsplash erosion, runoff and soil loss under field conditions. This study is a component of the European Union-funded BORASSUS Project. The effects of Borassus mats on rainsplash erosion were studied for ~2 years (2002-2004), and re-established in January 2007 on a 0o slope. There were 12 experimental plots (six plots completely-covered with mats and six bare plots; each measuring 1.0 x 1.0 m). Runoff-plot studies were also conducted on the loamy sand soil at Hilton for 2 years (2002-2004) with duplicate treatments: (i) bare soil; (ii) grassed, (iii) bare soil with 1 m Borassus-mat buffer zones at the lower end of the plots and (iv) completely-covered with Borassus-mats. Each plot was 10 x 1 m on a 15o (26.6%) slope. To confirm the results, another set of experiments have been in progress at Hilton since January 2007, with one additional treatment (bare soil with 1 m Buriti-mat buffer zones) compared with the earlier experiment. Runoff and soil erosion were collected from each plot in a concrete gutter, leading to a 0.02 m3 (20 liters) capacity receptacle placed inside a 0.14 m3 (140 liters) capacity container. Results (06/10/02-02/09/04; total precipitation = 1038.3 mm) showed Borassus mats on bare soil reduced total rainsplash erosion by ~50% compared with bare plots (9.64 kg m-2; 1.97 lb ft-2). The use of Borassus mats on bare soil (during 01/22/07-01/21/08; total precipitation = 919.2 mm) also reduced soil splash erosion by ~90%. During 03/25/02-05/10/04 (total precipitation = 1319.8 mm) complete cover of Borassus mats on bare soil reduced total runoff by ~19% and soil erosion by ~64%. Furthermore, Borassus mats as 1 m buffer strips on bare soil reduced runoff by ~36% and soil erosion by ~57%. During 01/08/07-01/14/08 (total precipitation = 923.4 mm), plots with Borassus and Buriti mats as buffer strips on bare soil reduced sediment yield by ~93 and 98%, respectively, and runoff by ~83 and 63%, respectively. Buffer strips of Borassus mats were also as effective as complete cover of the same mats. Thus, utilization of palm-mat geotextiles as buffer strips on bare plots (area coverage ~10%) is highly effective for soil and water conservation
Cathodoluminescence study of CdTe crystals doped with Bi and Bi : Yb
Get PDF© Springer Science+Business Media, LLC 2008.
This work was supported by Projects CAM (S-0505/MAT/0279) and MEC (project MAT 2006/1259).Bi doped and Bi and Yb codoped CdTe crystals grown by the Bridgman method have been characterized by cathodoluminescence (CL) in the scanning electron microscope. CL images show a dense network of highly decorated grain boundaries in the Bi doped samples and dopant striations in the codoped crystals, attributed to the presence of Yb. Bi contributes to the appearance of the A luminescence band at 1.43 eV. The influence of Yb dopant on the CL spectra is discussed.CAMMECDepto. de Física de MaterialesFac. de Ciencias FísicasTRUEpu
« MaT(i)erre(s) » : vers une architecture ?
Get PDFConfrontés aux évolutions environnementales et à une rupture des relations entre les architectures et les lieux, de nombreux architectes se tournent vers le redéveloppement des « MaT(i)erre(s) ». En recoupant les trajectoires de six architectes actifs sur ce sujet et en comparant leurs processus de conception, cet article s’interroge sur l’émergence d’un « mouvement environnemental » architectural et tente d’en définir les caractéristiques. Pour ce faire, il aborde les différents parcours de ces architectes et les questionnements qui les ont menés à cet intérêt pour les « MaT(i)erre(s) » et discute certaines de leurs orientations communes : repenser le rôle du matériau comme catalyseur de la conception ; réévaluer la coupure architecte/artisan ; favoriser expérimentation et recherche… Reflet des attentes des milieux, le mouvement environnemental des « MaT(i)erre(s) » fait souffler un « esprit nouveau ».Faced with environmental changes and a breakdown in the relationship between architecture and place, many architects are turning to the redevelopment of “MaT(i)erre(s)”. By intersecting the trajectories of six architects active on this subject and by comparing their design processes, this article questions the emergence of an architectural "environmental movement" and attempts to define its characteristics. To do this, it considers the various pathways and questionings of these architects which led them to their interest in “MaT(i)erre(s)”, and discusses some of their common orientations: rethinking the role of material as a catalyst for design; reassessing the architect/craftsman's estrangement; and promoting experimentation and research. Reflecting upon the milieux, the “MaT(i)erre(s)' Environmental Movement” unleashes an “Esprit Nouveau”
Meditation Awareness Training (MAT) for work-related wellbeing and job performance: a randomised controlled trial
Get PDFDue 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
Molecular dynamics simulations of proton conduction in sulfonated poly(phenyl sulfone)s
Get PDFFull molecular dynamics was used to simulate separately the diffusion of naked protons and H3O+
hydrated protons across sulfonated poly(phenyl sulfone)s. Simulations were carried out for wet membranes with
the following characteristics: ion-exchange capacity, 1.8 mequiv/g of dry membrane; water uptake, 10-30%;
temperature range, 300-360 K. The diffusion coefficient of naked protons is nearly 1 order of magnitude higher
than that of the hydrated protons for the membranes with the lower water uptake (10%). For the membranes with
higher water uptake the ratio between the diffusion coefficients of the two particles reduces to about half an
order of magnitude. The conductivity of the naked protons increases from 21.4 10-3 to 52.5 10-3 S/cm
when the water uptake increases from 10% to 30%. For hydrated protons the conductivity increases from 1.54
10-3 to 7.57 10-3 S/cm. The conductivities obtained through simulations carried out at 300 K for the hydrated
proton across membranes with water uptake 18% and 30% are roughly similar to those experimentally measured
for a membrane with ion exchange capacity ) 1.8 mequiv/g and water uptake ) 24.3%. Simulated conductivities
of both naked protons and hydrated protons follow Arrhenius behavior.This work was supported by the Comunidad
de Madrid through the grant interfaces S-0505/MAT-0227,
Fondos Europeos de Desarrollo (FEDER), and Fondo Social
Europeo (FSE). Financial support was also supplied by the
Dirección General de Investigación Científica y Técnica (DGICYT)
(grant MAT 2005-05648-C02-02)Peer reviewe
Mat lodge--Yakima
No full textPhotograph shows reed mat covered tepee in grassy field, Washington.Edward S. Curtis Collection.Curtis no. 3057-10.Published in: The North American Indian / Edward S. Curtis. [Seattle, Wash.] : Edward S. Curtis, 1907-30, v. 7, p. 4
A mat shelter--Skokomish
No full textTwo Skokomish women by mat shelter and rowboat.Edward S. Curtis Collection.Curtis no. 3464-12.Published in: The North American Indian / Edward S. Curtis. [Seattle, Wash.] : Edward S. Curtis, 1907-30, v. 9, p. 110
Semis - Sydenham 321b - Crawford 162/4
No full textThe moneyer is presumably a Matienus according to Crawford.ROMALaureate head of Saturn to right; behind, SProw to right; above, MAT (MAT ligatured); before, S; below, ROM
Low-Light Anoxygenic Photosynthesis and Fe-S-Biogeochemistry in a Microbial Mat
Get PDFWe report extremely low-light-adapted anoxygenic photosynthesis in a thick microbial mat in Magical Blue Hole, Abaco Island, The Bahamas. Sulfur cycling was reduced by iron oxides and organic carbon limitation. The mat grows below the halocline/oxycline at 30 m depth on the walls of the flooded sinkhole. In situ irradiance at the mat surface on a sunny December day was between 0.021 and 0.084 μmol photons m-2 s-1, and UV light (<400 nm) was the most abundant part of the spectrum followed by green wavelengths (475–530 nm). We measured a light-dependent carbon uptake rate of 14.5 nmol C cm-2 d-1. A 16S rRNA clone library of the green surface mat layer was dominated (74%) by a cluster (>97% sequence identity) of clones affiliated with Prosthecochloris, a genus within the green sulfur bacteria (GSB), which are obligate anoxygenic phototrophs. Typical photopigments of brown-colored GSB, bacteriochlorophyll e and (β-)isorenieratene, were abundant in mat samples and their absorption properties are well-adapted to harvest light in the available green and possibly even UV-A spectra. Sulfide from the water column (3–6 μmol L-1) was the main source of sulfide to the mat as sulfate reduction rates in the mats were very low (undetectable-99.2 nmol cm-3 d-1). The anoxic water column was oligotrophic and low in dissolved organic carbon (175–228 μmol L-1). High concentrations of pyrite (FeS2; 1–47 μmol cm-3) together with low microbial process rates (sulfate reduction, CO2 fixation) indicate that the mats function as net sulfide sinks mainly by abiotic processes. We suggest that abundant Fe(III) (4.3–22.2 μmol cm-3) is the major source of oxidizing power in the mat, and that abiotic Fe-S-reactions play the main role in pyrite formation. Limitation of sulfate reduction by low organic carbon availability along with the presence of abundant sulfide-scavenging iron oxides considerably slowed down sulfur cycling in these mats
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