3,094 research outputs found
Evaluation of agricultural ecosystem services in fallowing land based on farmers' participation and model simulation
Fallowing with green fertilizer can benefit agricultural ecosystem services (AES). Farmers in Taiwan do not implement fallow practices and plant green fertilizer because the current subsidy level (46,000 NTperha)istoolowtomanagefallowingThispaperdefinestheobjectiveofgovernmentagriculturepolicyorthefarmer’sobjectiveasmaximizationoffarmproductivityapproximatedtothevalueofsocialwelfareandAESFarmswhichdonotfollowproperfallowingpracticesoftenhavepoorlymaintainedfallowlandorleftfarmlandabandonedThisresultsinnegativeenvironmentalconsequencessuchascutworminfestationsinabandonedlandwhichinturncanaffectcropsinadjacentfarmlandsTheobjectivesofthisstudyaretwofoldFirstitdeterminestheproperfallowingsubsidybasedontheconceptofpaymentforecosystemservicestoenticemorefarmerstoparticipateinfallowingSeconditsimulatesthebenefitofplantinggreenmanureinfallowlandtothesupplyofAESbasedontherateoffarmerswhoarewillingtoparticipateinfallowlandpracticesandessentialparametersthatcanaffectsoilfertilitychangeTheapproachinvolvesaseriesofinterviewsandadevelopedempiricalmodelThevalueofAESwhentherateoffarmerparticipationis100 ) over the value at the current participation rate of 14%. This study further concludes that the appropriate fallowing subsidy has a large positive impact on AES and social welfare (e.g., benefit from food and biofuel supplies) and is seen as a basis of ecological governance for sustainable agro-ecosystems
Functional Diversity of Microbial Communities in Sludge-Amended Soils
AbstractThe BIOLOG method was applied to exploration of functional diversity of soil microbial communities in sludge-amended soils sampled from the Yangtze River Delta. Results indicated that metabolic profile, functional diversity indexes and Kinetic parameters of the soil microbial communities changed following soil amendment with sewage sludge, suggesting that the changes occurred in population of the microbes capable of exploiting carbon substrates and in this capability as well. The kinetic study of the functional diversity revealed that the metabolic profile of the soil microbial communities exhibited non-linear correlation with the incubation time, showing a curse of sigmoid that fits the dynamic model of growth of the soil microbial communities. In all the treatments, except for treatments of coastal fluvo-aquic soil amended with fresh sludge and dried sludge from Hangzhou, kinetic parameters K and r of the functional diversity of the soil microbial communities decreased significantly and parameter S increased. Changes in characteristics of the functional diversity well reflected differences in C utilizing capacity and model of the soil microbial communities in the sludge-amended soils, and changes in functional diversity of the soil microbial communities in a particular eco-environment, like soil amended with sewage sludge
Consuming Information Systems: An Economic Model of User Satisfaction
This paper has two major objectives. The first objective intends to answer the following question which is of significant interest to information system (IS) researchers and practitioners: How does user satisfaction (satisfaction) respond to changes in system use and system attributes? The second and more ambitious objective is to promote the application of economic theories in user behavior research. In contrast to prior research that conceived the development of user satisfaction as an information valuation and integration process, we consider such development to be embedded in the IS consumption process, that is, users gain utility (satisfaction) from consuming (using) the system. This perspective enables us to re-conceptualize user satisfaction as a proxy of utility and apply utility research in economics to study user satisfaction. An economic model of user satisfaction was developed. Two empirical studies were conducted to examine the research model. The findings confirmed the consumptive nature of user satisfaction. Apart from enriching our understanding of user satisfaction, this research demonstrates the usefulness of economic theories in user behavior research
CRT: A numerical tool for propagating ultra-high energy cosmic rays through Galactic magnetic field models
Deflection of ultra high energy cosmic rays (UHECRs) by the Galactic magnetic
field (GMF) may be sufficiently strong to hinder identification of the UHECR
source distribution. A common method for determining the effect of GMF models
on source identification efforts is backtracking cosmic rays. We present the
public numerical tool CRT for propagating charged particles through Galactic
magnetic field models by numerically integrating the relativistic equation of
motion. It is capable of both forward- and back-tracking particles with varying
compositions through pre-defined and custom user-created magnetic fields. These
particles are injected from various types of sources specified and distributed
according to the user. Here, we present a description of some source and
magnetic field model implementations, as well as validation of the integration
routines.Comment: 12 pages, 9 figure
The Non-Gaussianity of Racetrack Inflation Models
In this paper, we use the result in [7] to calculate the non-Gaussianity of
the racetrack models in [3, 5]. The two models give different non-
Gaussianities. Both of them are reasonable.Comment: 8 pages, no figures; PACS and Keywords are added; mistake is
correcte
Petrogenesis of the early Cretaceous intra-plate basalts from the western North China Craton: Implications for the origin of the metasomatized cratonic lithospheric mantle
We present new bulk-rock 40Ar/39Ar age, major and trace elements and Sr-Nd-Hf isotopic data on the early Cretaceous intra-plate alkali basalts from the Western North China Craton (WNCC) to study the origin of the metasomatized cratonic lithosphere mantle. The age of these basalts is ~116 Ma. These basalts have elevated incompatible element abundance with high [La/Sm]N (2.80–4.56) and enriched Sr-Nd-Hf isotopic compositions (87Sr/86Sri = 0.7062–0.7075, εNd(t) = −6.0 to −13.0 and εHf(t) = −8.3 to −17.4), being similar to the contemporary analogues from the Western North China Craton and Paleozoic kimberlites and mantle xenoliths. The WNCC basalts also show good correlations between ɛNd(t) and ɛHf(t), and high [La/Sm]N. All these geochemical observations are consistent with the interpretation that these basalts originated from partial melting of the lithospheric mantle that experienced melt metasomatism. Two types metasomatism melts are required to explain the geochemical characteristics of these rocks. The obvious negative Nbsingle bondTa (compared with K)-Ti and positive Basingle bondPb anomalies observed in these basalts further constrain that one of the metasomatic melts was derived from the subducted terrigenous sediment. Furthermore, the overall higher P/Nd, Nb/La and Nb/Th and lower Lu/Hf of basalts in the WNCC suggest that there is also contribution of low-F melts from asthenosphere mantle. Collectively, we suggest that the formation of the metasomatized lithosphere mantle beneath the WNCC is the process of metasomatic reaction between mantle peridotite and the melts of different origin to generate metasomatic veins containing amphibole/phlogopite. Partial melting of the metasomatic lithospheric mantle at 106–120 Ma in the WNCC was considered to be induced by thermal perturbation that was ultimately related to the breakoff of the subducted oceanic slab following the closure of the Mongolia-Okhotsk ocean
Combined blockade of CD28/B7 and CD40/CD40L costimulatory pathways prevents the onset of chronic rejection
Current driven switching of magnetic layers
The switching of magnetic layers is studied under the action of a spin
current in a ferromagnetic metal/non-magnetic metal/ferromagnetic metal spin
valve. We find that the main contribution to the switching comes from the
non-equilibrium exchange interaction between the ferromagnetic layers. This
interaction defines the magnetic configuration of the layers with minimum
energy and establishes the threshold for a critical switching current.
Depending on the direction of the critical current, the interaction changes
sign and a given magnetic configuration becomes unstable. To model the time
dependence of the switching process, we derive a set of coupled Landau-Lifshitz
equations for the ferromagnetic layers. Higher order terms in the
non-equilibrium exchange coupling allow the system to evolve to its
steady-state configuration.Comment: 8 pages, 2 figure. Submitted to Phys. Rev.
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