5,363 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
Combinatorial Voter Control in Elections
Voter control problems model situations such as an external agent trying to
affect the result of an election by adding voters, for example by convincing
some voters to vote who would otherwise not attend the election. Traditionally,
voters are added one at a time, with the goal of making a distinguished
alternative win by adding a minimum number of voters. In this paper, we
initiate the study of combinatorial variants of control by adding voters: In
our setting, when we choose to add a voter~, we also have to add a whole
bundle of voters associated with . We study the computational
complexity of this problem for two of the most basic voting rules, namely the
Plurality rule and the Condorcet rule.Comment: An extended abstract appears in MFCS 201
Using in situ technique to estimate nutrient availability of six barley varieties for ruminants
Non-Peer ReviewedBarley grains are as a main source of feed for ruminants in Canada. Although barley varieties have similar chemical composition, they exhibit different rumen degradation characteristics and nutrient availability. The objective of this study was to estimate nutrient availability of the six barley varieties using nylon bags incubated for 0, 2, 4, 8, 12, 24 and 48 h in the rumen of dairy cow and determine the rumen degradation parameters of DM, CP and starch according to the first order degradation kinetics equation. The results indicated that the barley varieties showed different degradation rate (Kd) of DM, CP and starch during incubation period. CDC Trey was the highest (P<0.05) in effective degradability of DM (498.04g/kg) while AC Metcalfe showed the highest (P<0.05) effective degradability of CP (63.06g/kg) and starch (344.82g/kg) compared with other barley varieties. CDC Helgason had the largest size of rumen undegradable fraction of DM (640.21g/kg), CP (83.85g/kg, NRC 2001 model) and starch (321.85g/kg). Feeds degradation features from this study involved nutrients utilization in ruminant digestive systems. Further study to investigate and compare the structural/chemical make-up characteristics between barley varieties may provide more information as to why barley varieties exhibit different biodegradation behaviors
Timing of closure of the Mesozoic-Tethys Ocean: Constraints from remnants of a 141-135 ocean island within the Bangong-Nujiang suture zone, Tibetan Plateau
Knowledge of the timing of the closure of the Meso-Tethys Ocean as represented by the Bangong–Nujiang Suture Zone, i.e., the timing of the Lhasa-Qiangtang collision, is critical for understanding the Mesozoic tectonics of the Tibetan Plateau. But this timing is hotly debated; existing suggestions vary from the Middle Jurassic (ca. 166 Ma) to Late Cretaceous (ca. 100 Ma). In this study, we describe the petrology of the Zhonggang igneous–sedimentary rocks in the middle segment of the Bangong–Nujiang Suture Zone and present results of zircon U–Pb geochronology, whole-rock geochemistry, and Sr–Nd isotope analysis of the Zhonggang igneous rocks. The Zhonggang igneous–sedimentary rocks have a thick basaltic basement (>2 km thick) covered by limestone with interbedded basalt and tuff, trachyandesite, chert, and poorly sorted conglomerate comprising limestone and basalt debris. There is an absence of terrigenous detritus (e.g., quartz) within the sedimentary and pyroclastic rocks. These observations, together with the typical exotic blocks-in-matrix structure between the Zhonggang igneous–sedimentary rocks and the surrounding flysch deposits, lead to the conclusion that the Zhonggang igneous–sedimentary rocks are remnants of an ocean island within the Meso-Tethys Ocean. This conclusion is consistent with the ocean island basalt-type geochemistry of the Zhonggang basalts and trachyandesites, which are enriched in light rare earth elements (LaN/YbN = 4.72–18.1 and 5.61–13.7, respectively) and have positive Nb–Ta anomalies (NbPM/ThPM > 1, TaPM/UPM > 1), low initial 87Sr/86Sr ratios (0.703992–0.705428), and positive mantle εNd(t) values (3.88–5.99). Zircon U–Pb dates indicate that the Zhonggang ocean island formed at 141–135 Ma; therefore, closure of the Meso-Tethys Ocean and collision of the Lhasa and Qiangtang terranes must have happened after ca. 135 Ma
Effects of Boundary Conditions on Single-File Pedestrian Flow
In this paper we investigate effects of boundary conditions on one
dimensional pedestrian flow which involves purely longitudinal interactions.
Qualitatively, stop-and-go waves are observed under closed boundary condition
and dissolve when the boundary is open. To get more detailed information the
fundamental diagrams of the open and closed systems are compared using
Voronoi-based measurement method. Higher maximal specific flow is observed from
the pedestrian movement at open boundary condition
Heavy flavor diffusion in weakly coupled N=4 Super Yang-Mills theory
We use perturbation theory to compute the diffusion coefficient of a heavy
quark or scalar moving in N=4 SU(N_c) Super Yang-Mills plasma to leading order
in the coupling and the ratio T/M<<1. The result is compared both to recent
strong coupling calculations in the same theory and to the corresponding weak
coupling result in QCD. Finally, we present a compact and simple formulation of
the Lagrangian of our theory, N=4 SYM coupled to a massive fundamental N=2
hypermultiplet, which is well-suited for weak coupling expansions.Comment: 22 pages, 4 figures; v3: error corrected in calculations, figures and
discussion modified accordingl
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