排序方式： 共有72条查询结果，搜索用时 343 毫秒
1.
Context
Landscape graphs are widely used to model connectivity and to support decision-making in conservation planning. Compartmentalization methods applied to such graphs aim to define clusters of highly interconnected patches. Recent studies show that compartmentalization based on modularity is suitable, but it applies to non-weighted graphs whereas most landscape graphs involve weighted nodes and links.Objectives
We propose to adapt modularity computation to weighted landscape graphs and to validate the relevance of the resulting compartments using demographic or genetic data about the patches.Methods
A weighted adjacency matrix was designed to express potential fluxes, associating patch capacities and inter-patch distances. Eight weighting scenarios were compared. The statistical evaluation of each compartmentalization was based on Wilks’ Lambda. These methods were performed on a grassland network where patches are documented by annual densities of water voles in the Jura massif (France).Results
The scenarios in which patch capacity is assigned a small weight led to the more relevant results, giving high modularity values and low Wilks’ Lambda values. When considering a fixed number of compartments, we found a significant negative correlation between these two criteria. Comparison showed that compartments are ecologically more valid than graph components.Conclusions
The method proposed is suitable for designing ecologically functional areas from weighted landscape graphs. Maximum modularity values can serve as a guide for setting the parameters of the adjacency matrix.2.
Uroy Léa Alignier Audrey Mony Cendrine Foltête Jean-Christophe Ernoult Aude 《Landscape Ecology》2021,36(9):2487-2504
Landscape Ecology - Landscape connectivity plays a key role in determining the persistence of species inhabiting fragmented habitat patches. In dynamic landscapes, most studies measure connectivity... 相似文献
3.
酸化剂对杜长大商品猪生产性能的影响 总被引：3，自引：1，他引：3
为探索酸化剂对杜长大系列商品猪生产性能的影响,将40头4周龄体重相近的杜长大(或杜大长)断奶仔猪随机分为4组(即对照组、添加酸化剂BGIFEX001组、添加酸化剂BGIFEX002组、添加酸化剂BGIFEX003组),每组10头(母猪和阉公猪各半),测定4周龄至90kg体重时的生长性能,并测定达90kg屠宰体重时的胴体性能及肉质性能。结果显示,BGIFEX001和BGIFEX002组有改善日增重和料重比的趋势,4～10周龄阶段料重比分别比对照组降低9.88%和8.70%,全期料重比分别降低5.19%和4.81%;各处理组未对屠宰和胴体性能产生显著影响;肉质测定结果显示酸化剂有显著改善肉的红度(a)和拿破率的效应(P<0.05),各处理间肉质常规参数和风味前体物质(脂肪酸和氨基酸)含量无显著差异。总体数据提示酸化剂BGIFEX001和BGIFEX002可在一定程度上改善杜长大商品猪的生长性能和肉品质量。 相似文献
4.
Ammonium oxidation coupled to dissimilatory reduction of iron under anaerobic conditions in wetland soils 总被引：1，自引：0，他引：1
Jean-Christophe Clément Junu Shrestha Peter R. Jaffé 《Soil biology & biochemistry》2005,37(12):2323-2328
In exploring the dynamics of iron and nitrogen cycling in sediments from riparian forests we have observed a redox reaction that has not been previously described. During incubations of soil slurries under strictly anaerobic conditions, we repeatedly measured an unexpected production of both nitrite () and ferrous iron [Fe(II)]. Using this indirect evidence we hypothesize that, under anaerobic conditions, there is a biological process that uses ferric iron [Fe(III)] as an electron acceptor while oxidizing ammonium () to for energy production. This oxidation under iron reducing anaerobic conditions is thermodynamically feasible and is potentially a critical component of the N cycle in saturated sediments. 相似文献
5.
Outeiro TF Kontopoulos E Altmann SM Kufareva I Strathearn KE Amore AM Volk CB Maxwell MM Rochet JC McLean PJ Young AB Abagyan R Feany MB Hyman BT Kazantsev AG 《Science (New York, N.Y.)》2007,317(5837):516-519
The sirtuins are members of the histone deacetylase family of proteins that participate in a variety of cellular functions and play a role in aging. We identified a potent inhibitor of sirtuin 2 (SIRT2) and found that inhibition of SIRT2 rescued alpha-synuclein toxicity and modified inclusion morphology in a cellular model of Parkinson's disease. Genetic inhibition of SIRT2 via small interfering RNA similarly rescued alpha-synuclein toxicity. Furthermore, the inhibitors protected against dopaminergic cell death both in vitro and in a Drosophila model of Parkinson's disease. The results suggest a link between neurodegeneration and aging. 相似文献
6.
da Silva Ferreira AC Barbe JC Bertrand A 《Journal of agricultural and food chemistry》2002,50(9):2560-2564
In Port wine, isomers of glycerol and acetaldehyde acetals have been found at total contents ranging from 9.4 to 175.3 mg/L. During oxidative aging, the concentrations of the 5-hydroxy-2-methyl-1,3-dioxane and 4-hydroxymethyl-2-methyl-1,3-dioxolane isomers increased with time showing a linear correlation (r > 0.95). The flavor threshold for the mixture of the four isomers was evaluated in wine at 100 mg/L. Thus, it is expected that they contribute to "old Port wine" aroma in wines older than 30 years. Experiments with model solutions and wine clearly demonstrated that SO(2) combines with acetaldehyde and blocks the acetalization reaction. 相似文献
7.
Kar A Jacquier JC Morgan DJ Lyng JG McKenna BM 《Journal of agricultural and food chemistry》2005,53(21):8259-8264
The influence of the lipid extraction process on both macroscopic and microscopic characteristics of nonwaxy rice starch gelatinization in excess water was examined. Surface lipids extraction did not change the thermodynamics of starch gelatinization but lead to a significant reduction (33%) in the enthalpy of starch-lipid complex melting at high temperature, resulting in less viscous dispersions. Internal lipid extraction using hot aqueous alcoholic solutions resulted in an irreversible increase in starch granule diameter (50% increase in D[4,3]) and a dramatic change in cooking characteristics of the starch. Instead of the bimodal swelling observed for native nonwaxy rice starch, only one broad transition in swelling, solubility, granule size, and viscosity was observed in the case of the totally defatted starch. While the total removal of lipids resulted in a slight increase in starch swelling at intermediate temperatures, the harshness of the process caused irreparable changes leading to notably lower swelling at high temperatures. 相似文献
8.
Jean-Pierre Wigneron Jean-Christophe Calvet Yann Kerr 《Agricultural and Forest Meteorology》1996,80(2-4)
In the present work, the time variations of a wheat field microwave emission are analysed during irrigation phases. The aim of the study is to investigate the use of low-frequency microwave measurements to monitor hydrological variables over a wheat crop: surface soil moisture and water interception by the vegetation canopy. The irrigation phases were representative of rainfall or dew events. It appears that the radiometric measurements are strongly sensitive to the hydrological characteristics of the soil and of the vegetation canopy. The 1.4GHz measurements are mainly sensitive to surface soil moisture mv, whereas the 5 GHz measurements are sensitive to both mv and to the vegetation water content Wv. A simple model approach is implemented to retrieve simultaneously these two surface parameters. The results of this procedure show the high potential of the microwave remote sensing measurements to monitor the time variations of soil moisture and of the total vegetation water content. The value of the wheat water storage capacity is derived from the microwave measurements and is in good agreement with experimental data. 相似文献
9.
Domec JC Ogée J Noormets A Jouangy J Gavazzi M Treasure E Sun G McNulty SG King JS 《Tree physiology》2012,32(6):707-723
Deep root water uptake and hydraulic redistribution (HR) have been shown to play a major role in forest ecosystems during drought, but little is known about the impact of climate change, fertilization and soil characteristics on HR and its consequences on water and carbon fluxes. Using data from three mid-rotation loblolly pine plantations, and simulations with the process-based model MuSICA, this study indicated that HR can mitigate the effects of soil drying and had important implications for carbon uptake potential and net ecosystem exchange (NEE), especially when N fertilization is considered. At the coastal site (C), characterized by deep organic soil, HR increased dry season tree transpiration (T) by up to 40%, and such an increase affected NEE through major changes in gross primary productivity (GPP). Deep-rooted trees did not necessarily translate into a large volume of HR unless soil texture allowed large water potential gradients to occur, as was the case at the sandy site (S). At the Piedmont site (P) characterized by a shallow clay-loam soil, HR was low but not negligible, representing up to 10% of T. In the absence of HR, it was predicted that at the C, S and P sites, annual GPP would have been diminished by 19, 7 and 9%, respectively. Under future climate conditions HR was predicted to be reduced by up to 25% at the C site, reducing the resilience of trees to precipitation deficits. The effect of HR on T and GPP was predicted to diminish under future conditions by 12 and 6% at the C and P sites, respectively. Under future conditions, T was predicted to stay the same at the P site, but to be marginally reduced at the C site and slightly increased at the S site. Future conditions and N fertilization would decrease T by 25% at the C site, by 15% at the P site and by 8% at the S site. At the C and S sites, GPP was estimated to increase by 18% and by >70% under future conditions, respectively, with little effect of N fertilization. At the P site, future conditions would stimulate GPP by only 12%, but future conditions plus N fertilization would increase GPP by 24%. As a consequence, in all sites, water use efficiency was predicted to improve dramatically with future conditions. Modeling the effect of reduced annual precipitation indicated that limited water availability would decrease all carbon fluxes, including NEE and respiration. Our simulations highlight the interactive effects of nutrients and elevated CO(2), and showed that the effect of N fertilization would be greater under future climate conditions. 相似文献
10.
François Courbet Jean-Christophe Hervé Etienne K. Klein Francis Colin 《Annals of Forest Science》2012,69(2):125-138