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51.
Mark Moritz Eric Soma Paul Scholte Ningchuan Xiao Leah Taylor Todd Juran Saïdou Kari 《Human ecology: an interdisciplinary journal》2010,38(6):775-789
The discussion about the impact of pastoral systems on ecosystems has been profoundly shaped by Hardin’s “tragedy of the commons”
argument that held pastoralists responsible for overgrazing the range. Recent studies have shown that grazing ecosystems are
much more complex and dynamic than was previously assumed and that pastoralists adaptively manage these systems. However,
we still have little understanding how everyday herding affects ecosystems at the landscape level. We conducted a study of
daily herd movements and grazing strategies in a mobile pastoral system in the Logone floodplain, Cameroon. We integrated
GPS/GIS technology, video recordings of animal behavior, and ethnographic methods to develop a more accurate measurement of
grazing pressure that takes into account both livestock densities and grazing behavior. We used the resulting grazing pressure
data to evaluate existing conceptual models of grazing pressure at a landscape level. We found that models that predict that
grazing pressure is skewed towards the direction of water most accurately reflect the situation in the Logone floodplain in
the dry season. However, we found that the higher grazing pressure is not only the result of a higher density of cattle but
also a change in the grazing behavior of animals after watering. Finally, we caution that the models of grazing pressure in
the dry season cannot simply be extrapolated to the landscape level because mobile pastoralists do not remain in one central
place. 相似文献
52.
Myriam Declercq Merianne Alkio Thorben Sprink Lukas Schreiber Moritz Knoche 《Tree Genetics & Genomes》2014,10(6):1711-1721
The cuticular membrane (CM) of sweet cherry (Prunus avium L.) fruit is severely strained during development. Strain results from a cessation of CM deposition during early development and is possibly caused by a downregulation of genes involved in CM synthesis. The objectives of our study were to investigate the effects of ectopic expression of two sweet cherry genes, PaLACS2 (a putative long-chain acyl-CoA synthetase) and PaATT1 (a putative cytochrome P450 monooxygenase), in Arabidopsis thaliana (L.). Effects on the expression of endogenous LACS2, ATT1 and LACS1 genes, wax and cutin composition, and cuticle permeability were investigated in 13 transgenic lines. Of these, six lines are selected for presentation based on the magnitude of the response. The amount of cutin increased in the PaLACS2 overexpression line C-L-29 and in the complemented lacs2-1 knockout mutant line l-L-14, but overexpression had no effect on cutin composition or wax. Wax deposition decreased in the complemented knockout lines l-L-14 and l-L-21. Overexpressing PaATT1 in A. thaliana line C-A-6 had no significant effect on cutin and wax deposition. In the complemented knockout lines a-A-7 and a-A-12, cutin deposition increased, whereas wax deposition was unaffected. The permeability of the cuticle for water and toluidine blue decreased in the PaLACS2 and PaATT1 complemented knockout lines. The results suggest that (1) PaLACS2 and PaATT1 expressed in A. thaliana are involved in cutin biosynthesis, and (2) their functions are consistent with those of a typical long-chain acyl-CoA synthetase (PaLACS2) and of a cytochrome P450 monooxygenase (PaATT1). 相似文献
53.
Pinto José de Azevedo Cristiana Rodrigues Oliveira Rui von Stosch Moritz 《Bioprocess and biosystems engineering》2019,42(11):1853-1865
Bioprocess and Biosystems Engineering - Hybrid semi-parametric modeling, combining mechanistic and machine-learning methods, has proven to be a powerful method for process development. This paper... 相似文献
54.
Filip Logist Dries Telen Boris Houska Moritz Diehl Jan Van Impe 《Bioprocess and biosystems engineering》2013,36(2):151-164
The optimal design and operation of dynamic bioprocesses gives in practice often rise to optimisation problems with multiple and conflicting objectives. As a result typically not a single optimal solution but a set of Pareto optimal solutions exist. From this set of Pareto optimal solutions, one has to be chosen by the decision maker. Hence, efficient approaches are required for a fast and accurate generation of the Pareto set such that the decision maker can easily and systematically evaluate optimal alternatives. In the current paper the multi-objective optimisation of several dynamic bioprocess examples is performed using the freely available ACADO Multi-Objective Toolkit (http://www.acadotoolkit.org). This toolkit integrates efficient multiple objective scalarisation strategies (e.g., Normal Boundary Intersection and (Enhanced) Normalised Normal Constraint) with fast deterministic approaches for dynamic optimisation (e.g., single and multiple shooting). It has been found that the toolkit is able to efficiently and accurately produce the Pareto sets for all bioprocess examples. The resulting Pareto sets are added as supplementary material to this paper. 相似文献
55.
Testing the stages model in the adaptive radiation of cichlid fishes in East African Lake Tanganyika
Moritz Muschick Patrik Nosil Marius Roesti Marie Theres Dittmann Luke Harmon Walter Salzburger 《Proceedings. Biological sciences / The Royal Society》2014,281(1795)
Adaptive radiation (AR) is a key process in the origin of organismal diversity. However, the evolution of trait disparity in connection with ecological specialization is still poorly understood. Available models for vertebrate ARs predict that diversification occurs in the form of temporal stages driven by different selective forces. Here, we investigate the AR of cichlid fishes in East African Lake Tanganyika and use macroevolutionary model fitting to evaluate whether diversification happened in temporal stages. Six trait complexes, for which we also provide evidence of their adaptiveness, are analysed with comparative methods: body shape, pharyngeal jaw shape, gill raker traits, gut length, brain weight and body coloration. Overall, we do not find strong evidence for the ‘stages model’ of AR. However, our results suggest that trophic traits diversify earlier than traits implicated in macrohabitat adaptation and that sexual communication traits (i.e. coloration) diversify late in the radiation. 相似文献
56.
57.
Plasmacytoid dendritic cells control TLR7 sensitivity of naive B cells via type I IFN 总被引:8,自引:0,他引:8
Bekeredjian-Ding IB Berkeredjian-Ding IB Wagner M Hornung V Giese T Schnurr M Endres S Hartmann G 《Journal of immunology (Baltimore, Md. : 1950)》2005,174(7):4043-4050
Detailed information of human B cell activation via TLR may lead to a better understanding of B cell involvement in autoimmunity and malignancy. In this study we identified a fundamental difference in the regulation of TLR7- and TLR9-mediated B cell stimulation: whereas the induction of polyclonal naive B cell proliferation by the TLR7 ligands resiquimod (R848) and loxoribine required the presence of plasmacytoid dendritic cells (PDCs), activation via the TLR9 ligand CpG was independent of PDCs. We found that PDC-derived type I IFN enhanced TLR7 sensitivity of B cells by selectively up-regulating TLR7 expression. In contrast the expression levels of TLR9 and of other TLRs studied remained unchanged. In the presence of type I IFN, TLR7 ligation triggered polyclonal B cell expansion and B cell differentiation toward Ig-producing plasma cells; notably, this occurred independently of T cell help and B cell Ag. Human B cells did not respond to ligands of other TLRs including TLR2, TLR4 and TLR6 with and without type I IFN. In conclusion, our results reveal a distinct regulation of TLR7 and TLR9 function in human B cells and highlight TLR7 and TLR9 as unique targets for therapeutic intervention in B cell-mediated immunity and disease. 相似文献
58.
Active aggregation among sexes in bean flower thrips (Megalurothrips sjostedti) on cowpea (Vigna unguiculata) 总被引:1,自引:0,他引:1 下载免费PDF全文
Saliou Niassy Sunday Ekesi Nguya K. Maniania Benedict Orindi Gerald B. Moritz Willem J. de Kogel Sevgan Subramanian 《Entomologia Experimentalis et Applicata》2016,158(1):17-24
Male sexual aggregations are a common territorial, mating‐related or resource‐based, behaviour observed in diverse organisms, including insects such as thrips. The influence of factors such as plant substrate, time of day, and geographic location on aggregation of thrips is uncertain, therefore we monitored the dispersion of male and female bean flower thrips (BFT), Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae), on cowpea, Vigna unguiculata (L.) Walp. (Fabaceae), over three cowpea growth stages and across three cowpea‐growing areas of Kenya. Our results indicated that for all the crop growth stages, the density of BFTs varied over the time of day, with higher densities at 10:00, 13:00, and 16:00 hours than at 07:00 hours. Thrips densities did not differ among blocks at the budding stage, but they did at peak flowering and podding stages. Dispersion indices suggested that both male and female BFTs were aggregated. Active male aggregation occurred only on green plant parts and it varied across blocks, crop stages, and locations. Similarly, active female aggregation was observed in peak flowering and podding stages. Such active aggregation indicates a semiochemical or behaviour‐mediated aggregation. Identification of such a semiochemical may offer new opportunities for refining monitoring and management strategies for BFT on cowpea, the most important grain legume in sub‐Saharan Africa. 相似文献
59.
Jane Elith Catherine H. Graham Robert P. Anderson Miroslav Dudík Simon Ferrier Antoine Guisan Robert J. Hijmans Falk Huettmann John R. Leathwick Anthony Lehmann Jin Li Lucia G. Lohmann Bette A. Loiselle Glenn Manion Craig Moritz Miguel Nakamura Yoshinori Nakazawa Jacob McC. M. Overton A. Townsend Peterson Steven J. Phillips Karen Richardson Ricardo Scachetti-Pereira Robert E. Schapire Jorge Soberón Stephen Williams Mary S. Wisz Niklaus E. Zimmermann 《Ecography》2006,29(2):129-151
Prediction of species' distributions is central to diverse applications in ecology, evolution and conservation science. There is increasing electronic access to vast sets of occurrence records in museums and herbaria, yet little effective guidance on how best to use this information in the context of numerous approaches for modelling distributions. To meet this need, we compared 16 modelling methods over 226 species from 6 regions of the world, creating the most comprehensive set of model comparisons to date. We used presence-only data to fit models, and independent presence-absence data to evaluate the predictions. Along with well-established modelling methods such as generalised additive models and GARP and BIOCLIM, we explored methods that either have been developed recently or have rarely been applied to modelling species' distributions. These include machine-learning methods and community models, both of which have features that may make them particularly well suited to noisy or sparse information, as is typical of species' occurrence data. Presence-only data were effective for modelling species' distributions for many species and regions. The novel methods consistently outperformed more established methods. The results of our analysis are promising for the use of data from museums and herbaria, especially as methods suited to the noise inherent in such data improve. 相似文献
60.
Mi-Youn K Brusniak Sung-Tat Kwok Mark Christiansen David Campbell Lukas Reiter Paola Picotti Ulrike Kusebauch Hector Ramos Eric W Deutsch Jingchun Chen Robert L Moritz Ruedi Aebersold 《BMC bioinformatics》2011,12(1):1-15