422 research outputs found
Conflict-free strides for vectors in matched memories
Address transformation schemes, such as skewing and linear transformations, have been proposed to achieve conflict-free access to one family of strides in vector processors with matched memories. The paper extends these schemes to achieve this conflict-free access for several families. The basic idea is to perform an out-of-order access to vectors of fixed length, equal to that of the vector registers of the processor. The hardware required is similar to that for the access in order.Peer ReviewedPostprint (author's final draft
Osmotically driven flows in microchannels separated by a semipermeable membrane
We perform experimental investigations of osmotically driven flows in
artificial microchannels by studying the dynamics and structure of the front of
a sugar solution traveling in 200 um wide and 50-200 um deep microchannels. We
find that the sugar front travels with constant speed, and that this speed is
proportional to the concentration of the sugar solution and inversely
proportional to the depth of the channel. We propose a theoretical model,
which, in the limit of low axial flow resistance, predicts that the sugar front
indeed should travel with a constant velocity. The model also predicts an
inverse relationship between the depth of the channel and the speed and a
linear relation between the sugar concentration and the speed. We thus find
good agreement between the experimental results and the predictions of the
model. Our motivation for studying osmotically driven flows is that they are
believed to be responsible for the translocation of sugar in plants through the
phloem sieve element cells. Also, we suggest that osmotic elements can act as
integrated pumps with no movable parts in lab-on-a-chip systems.Comment: 7 Pages, submitted to Lab-on-a-chip on October 24th, 200
La importancia del carbón marrón radica en la creciente necesidad energética que existe en la República Checa. En la actualidad es el combustible fósil del cual depende la nación, de lo contrario tendría que importar recursos energéticos. Más del 70% del
ABSTRACT
The importance of brown coal implies from the growing need of energy in the Czech Republic. It is nowadays a single signifcant fossil raw material, without which our state would become fully dependent on the import of energetic sources. More than 70 % of mined brown coal comes from the North Bohemian Basin these days. Open cast brown coal mining has lead to large damage on the landscape. That is why the reclamation work has become important on principle recently.
The diffculty of reclamation of North Bohemian localities consists in extremely unfavourable properties of rock strewn to the most of dump bodies. These rocks are mechanically unstable in the wind and water erosion and it gets undesirable, acidic characteristics as SO3 and Al ions infuence by weathering. Limitation of the infuence of weathering, amendment of chemistry and physical composition of top rocks strata, and defnition of the required amount of fertilizable rock have been successful in recent years as suitable methods have been used. The presented article includes the characteristics of the important phytotoxic areas and the methodology of their reclamation mainly based on the application of suitable fertilizable rocks. Some tentatively used non-traditional methods were evaluated e. g. the application power plant stabilizer and ash. The paper assesses the success rate of the reclamation methods.
The results are documented with the long term monitoring of physical, mineralogical, chemical and pedological parameters of rocks in the testing areas.
Keywords: non-traditional restoration methods, reclamation, application power plant stabilizer and ash.
 
Spatio-temporal patterns in arctic fox (Vulpes alopex) diets revealed by molecular analysis of scats from Northeast Greenland
The arctic fox (Vulpes lagopus) is endemic to the Arctic where it holds a central position in the trophic interactions. The diet of the species has previously been described as being highly flexible, but whether this flexibility is a constant trait through time, or merely reflects fast temporal changes in abundance among prey taxa, has so far been poorly resolved. Using molecular analyses of arctic fox scats from Northeast Greenland, we first examined the temporal dynamics of arctic fox diets during the short snow-free season, and then examined whether local food availability at different sites affected arctic fox dependence on lemmings. Arctic fox diets included most terrestrial vertebrate species found in the region, and exhibited substantial temporal changes, generally reflecting the dynamic changes in prey availability from late winter through autumn. This dietary flexibility was also reflected geographically, with arctic foxes consuming a variety of local prey (mainly waterfowl and lemmings) in summer. Moreover, the dietary response of arctic foxes to changes in lemming abundance depended on access to non-lemming prey. Based on these findings, we discuss whether varying degrees of lemming-dependency, combined with geographical differences in winter food availability, may explain previously published differences in arctic fox breeding patterns in high arctic Greenland.Peer reviewe
Detecting Areas of Potential High Prevalence of Chagas in Argentina
A map of potential prevalence of Chagas disease (ChD) with high spatial
disaggregation is presented. It aims to detect areas outside the Gran Chaco
ecoregion (hyperendemic for the ChD), characterized by high affinity with ChD
and high health vulnerability.
To quantify potential prevalence, we developed several indicators: an
Affinity Index which quantifies the degree of linkage between endemic areas of
ChD and the rest of the country. We also studied favorable habitability
conditions for Triatoma infestans, looking for areas where the predominant
materials of floors, roofs and internal ceilings favor the presence of the
disease vector.
We studied determinants of a more general nature that can be encompassed
under the concept of Health Vulnerability Index. These determinants are
associated with access to health providers and the socio-economic level of
different segments of the population.
Finally we constructed a Chagas Potential Prevalence Index (ChPPI) which
combines the affinity index, the health vulnerability index, and the population
density. We show and discuss the maps obtained. These maps are intended to
assist public health specialists, decision makers of public health policies and
public officials in the development of cost-effective strategies to improve
access to diagnosis and treatment of ChD.Comment: Proceedings of the 2019 World Wide Web Conference. May 13-17, 2019.
San Francisco, CA, US
Spatio-temporal patterns in arctic fox (Vulpes alopex) diets revealed by molecular analysis of scats from Northeast Greenland
The arctic fox (Vulpes lagopus) is endemic to the Arctic where it holds a central position in the trophic interactions. The diet of the species has previously been described as being highly flexible, but whether this flexibility is a constant trait through time, or merely reflects fast temporal changes in abundance among prey taxa, has so far been poorly resolved. Using molecular analyses of arctic fox scats from Northeast Greenland, we first examined the temporal dynamics of arctic fox diets during the short snow-free season, and then examined whether local food availability at different sites affected arctic fox dependence on lemmings. Arctic fox diets included most terrestrial vertebrate species found in the region, and exhibited substantial temporal changes, generally reflecting the dynamic changes in prey availability from late winter through autumn. This dietary flexibility was also reflected geographically, with arctic foxes consuming a variety of local prey (mainly waterfowl and lemmings) in summer. Moreover, the dietary response of arctic foxes to changes in lemming abundance depended on access to non-lemming prey. Based on these findings, we discuss whether varying degrees of lemming-dependency, combined with geographical differences in winter food availability, may explain previously published differences in arctic fox breeding patterns in high arctic Greenland.Peer reviewe
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