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1.
The interstitial assemblages of the River Rhine were studied in the Rhinau sector (France). The studied area is located in aVegulated channel of the river, controlled by a hydroelectric dam. Twenty stations were sampled in September 1988. Ten litres of interstitial water were pumped at 50 cm depth in each station using the Bou-Rouch technique. Interstitial waters were poorly oxygenated and the hyporheic fauna had three major characteristics: (1) microcrustaceans were dominant, (2) the insects were rare and (3) the stygofauna was absent. The richest stations were well oxygenated and did not correspond to any particular geomorphological features. These findings contrast with the situation observed on other large European rivers (Rhǒne, Danube) where the interstitial assemblages appear to be locally more diversified and rich in stygofauna. 相似文献
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We consider the behaviour of a stochastic system composed of several identically distributed, but non independent, discrete-time absorbing Markov chains competing at each instant for a transition. The competition consists in determining at each instant, using a given probability distribution, the only Markov chain allowed to make a transition. We analyse the first time at which one of the Markov chains reaches its absorbing state. When the number of Markov chains goes to infinity, we analyse the asymptotic behaviour of the system for an arbitrary probability mass function governing the competition. We give conditions that ensure the existence of the asymptotic distribution and we show how these results apply to cluster-based distributed storage when the competition is handled using a geometric distribution. 相似文献
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The study examines the relationship between floodplain aquatic macroinvertebrates and sector-scale parameters such as geomorphology and history of regulation. The assemblages of six groups of invertebrates (Molluscs, Crustaceans, Ephemeroptera, Odonata, Trichoptera, and Coleoptera) were compared in various types of former channels from two contrasting but adjacent floodplain sectors: (1) the Jons sector of the Rhǒne River where successive meandering and braiding phases has left diversified fluvial forms in the landscape but where the main river is now embanked, and (2) the unregulated Ain River sector where the river is still actively meandering, although this process is being slowed by incision. The results demonstrate little difference in faunal composition between the two sectors but a significant difference in faunal structure. In the Rhǒne floodplain, there was a clear distinction between the faunal assemblages together with a high taxa richness at the scale of the sector (dominance of the beta diversity). In the Ain floodplain, the faunal assemblages were overlapping and the taxa richness was high at the sample scale (alpha diversity). Sector-scale spatial patterns of the faunal assemblages along former channels were also distinct: between-channel heterogeneity dominated in the Rhǒne, whereas within-channel heterogeneity dominated on the Ain. These results stress the influence of geomorphological and historical determinants on the floodplain communities and, conversely, the relevance of macroinvertebrate assemblages for the assessment, at the landscape scale, of aquatic systems within the floodplains. 相似文献
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Comparing the input, output, and validation maps for several models of land change 总被引:31,自引:0,他引:31
Robert Gilmore Pontius Jr Wideke Boersma Jean-Christophe Castella Keith Clarke Ton de Nijs Charles Dietzel Zengqiang Duan Eric Fotsing Noah Goldstein Kasper Kok Eric Koomen Christopher D. Lippitt William McConnell Alias Mohd Sood Bryan Pijanowski Snehal Pithadia Sean Sweeney Tran Ngoc Trung A. Tom Veldkamp Peter H. Verburg 《The Annals of Regional Science》2008,42(1):11-37
This paper applies methods of multiple resolution map comparison to quantify characteristics for 13 applications of 9 different
popular peer-reviewed land change models. Each modeling application simulates change of land categories in raster maps from
an initial time to a subsequent time. For each modeling application, the statistical methods compare: (1) a reference map
of the initial time, (2) a reference map of the subsequent time, and (3) a prediction map of the subsequent time. The three
possible two-map comparisons for each application characterize: (1) the dynamics of the landscape, (2) the behavior of the
model, and (3) the accuracy of the prediction. The three-map comparison for each application specifies the amount of the prediction’s
accuracy that is attributable to land persistence versus land change. Results show that the amount of error is larger than
the amount of correctly predicted change for 12 of the 13 applications at the resolution of the raw data. The applications
are summarized and compared using two statistics: the null resolution and the figure of merit. According to the figure of
merit, the more accurate applications are the ones where the amount of observed net change in the reference maps is larger.
This paper facilitates communication among land change modelers, because it illustrates the range of results for a variety
of models using scientifically rigorous, generally applicable, and intellectually accessible statistical techniques. 相似文献
7.
Dolors Parés M. Àngels Pèlach Mònica Toldrà Elena Saguer Quim Tarrés Carmen Carretero 《Food and Bioprocess Technology》2018,11(7):1393-1401
The objective of this work was to introduce nanofibrillated cellulose (NFC) in the formulation of cooked emulsion-type sausages with the aim of assessing its feasibility to assume the role or compensate the lack of some conventional functional ingredients, such as polyphosphates, maize starch, and sodium caseinate. For this aim, sausages based on standard commercial formula (control) including all three ingredients and sausages containing 0.5% NFC instead of phosphates and starch (NFC-1) or instead of phosphates, starch, and sodium caseinate (NFC-2) were produced and characterized. In NFC-1 samples, 0.5% nanofibrillated cellulose succeeds in replacing 0.5% polyphosphates and 1% starch without significantly altering the composition, nor negatively affecting the fat and water retention properties, neither of the raw batter or the cooked sausages. However, less stable meat batters and sausages with significantly reduced water-holding capacity were obtained when 1.5% sodium caseinate, in addition to phosphates and starch, was also removed (NFC-2). Nevertheless, results were hopeful enough to encourage further optimization studies, using several NFC concentrations and/or cellulose with different nanofibrillation degrees, in order to clarify whether it is possible to successfully replace also non-meat proteins in cooked emulsion-type sausages. 相似文献
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A Alvarez-Castells S Pedraza N Tallada E Castella L Gifre C Torrents 《Canadian Metallurgical Quarterly》1993,17(3):408-409
Two cases of bilateral primary adrenal lymphoma are presented. One case had a cystic appearance and the other a homogeneous density. 相似文献
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Anna Karla de Carvalho Freitas Bruna Maria Saorin Puton Ana Paula da Silva Peres Rogério Luis Cansian Sibele Berenice Castella Pergher Wilson Acchar 《International Journal of Applied Ceramic Technology》2020,17(1):320-326
The main objective was to increase the applicability of palygorskite by palygorskite sheets using a tape casting method. The stability of the suspension was investigated and the tapes were characterized by TGA/DTA, XRD, and SEM-FEG. The antimicrobial activity was analyzed in order to test the applicability of a newly modified drug release system that incorporates neomycin in palygorskite. Preliminary results showed that the palygorskite sheet prepared via the tape casting is promising for wound healing applications. 相似文献
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A family of frequency- and time-domain contrasts for blind separation of convolutive mixtures of temporally dependent signals 总被引:2,自引:0,他引:2
Castella M. Pesquet J.-C. Petropulu A.P. 《Signal Processing, IEEE Transactions on》2005,53(1):107-120
This paper addresses the problem of blind separation of convolutive mixtures via contrast maximization. New frequency domain contrast functions are constructed based on higher order spectra of the observations. They allow to separate mixtures of sources that are spatially independent and temporally possibly nonlinear processes. Using Parseval's formula, the former criteria yield a general class of time-domain contrasts, which extends to the convolutive case results that have been previously obtained in the context either of instantaneous mixtures or of independent and identically distributed (i.i.d.) sources. A Monte Carlo simulation study is carried out for comparison between the different contrasts, thus providing a guideline about the choice of an appropriate contrast. 相似文献