2,177 research outputs found

    Water management improvements for agriculture by applying efficient crop schedules in the highland forest of Vilcabamba, Peru

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    The current work is aimed to improve the water management for agriculture, by applying efficient crop schedules in Vilcabamba -and similar areas of the Andean highland forest-, which can satisfy most of the water requirements with rainfed irrigation and maximise the crops yield.  For this purpose, two field practices were carried out during the dry (September 2012) and wet season (February 2013) to measure rivers and canals flows with the velocity/area method.  Nineteen soil samples were collected on-site and analysed, presenting prevalent sandy loam and loam textures.  Cropwat programme and data on climate, crops and soil were used to estimate crop water requirements and scheme irrigation requirements, indicating that crop evapotranspiration is low due to humidity and cool temperature.  Crops did not need any water during the rainy season (December to April), although irrigation requirements occur in the dry season, with a maximum flow capacity of 1.72 L/s in May.  The flow capacity can be satisfied, since small ditches convey approximately 2 L/s to 6 L/s on the same season.  Rainfed farming can be practised, but an initial pre-irrigation that needs to be applied for crops should not be water stressed.  However, if soil is not pre-irrigated the production can be affected, with vegetables and potato crop yields reduced by 4.7% and 1.4%, respectively.  To minimise these effects, both crops are suggested to be planted one month later, adapting their growth period to the rainy season.   Keywords: Crop scheduling, crop water requirements, rainfed irrigation, water management for agriculture, Cropwa

    Multi-field representations of KP hierarchies and multi-matrix models

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    We discuss the integrable hierarchies that appear in multi--matrix models. They can be envisaged as multi--field representations of the KP hierarchy. We then study the possible reductions of this systems via the Dirac reduction method by suppressing successively one by one part of the fields. We find in this way new integrable hierarchies, of which we are able to write the Lax pair representations by means of suitable Drinfeld--Sokolov linear systems. At the bottom of each reduction procedure we find an NN--th KdV hierarchy. We discuss in detail the case which leads to the KdV hierarchy and to the Boussinesque hierarchy, as well as the general case in the dispersionless limit.Comment: 14 pages, LaTeX, SISSA 53/93/EP, ASITP 93-2

    A Boundary Meshless Method Using Chebyshev Interpolation and Trigonometric Basis Function for Solving Heat Conduction Problems

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    A boundary meshless method has been developed to solve the heat conduction equations through the use of a newly established two-stage approximation scheme and a trigonometric series expansion scheme to approximate the particular solution and fundamental solution, respectively. As a result, no fundamental solution is required and the closed form of approximate particular solution is easy to obtain. The effectiveness of the proposed computational scheme is demonstrated by several examples in 2D and 31). We also compare our proposed method with the finite-difference method and the other meshless method showed in Sarler and Vertnik (Comput. Math. Appl. 2006; 51:1269-1282). Excellent numerical results have been observed. Copyright (C) 2007 John Wiley & Sons, Ltd

    Did Information Amount Matter in Framing Effect?

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    Framing the product attribute(s) in either positive or negative way can result in different responses. This phenomenon is referred to attribute framing effect. This article reported results from a laboratory experiment which examines the influence of message framing and information amounts on Internet buyers’ judgments. The amount of information was defined in terms of the number of attribute information of the target product. The result indicated significant framing effects no matter how much attribute information was presented. Positive information leads to more favorable responses than negative information. In addition, respondents who were exposed to more amounts of positive information showed more favorable evaluations than those who were exposed to less amounts of positive information condition. However, more amounts of negative information did not result in less favorable responses

    Saturation and Wilson Line Distributions

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    We introduce a Wilson line distribution function bar{W}_tau(v) to study gluon saturation at small Feynman x_F, or large tau=ln(1/x_F). This new distribution can be obtained from the distribution W_tau(alpha) of the Color Glass Condensate model and the JIMWLK renormalization group equation. bar{W}_tau(v) is physically more relevant, and mathematically simpler to deal with because of unitarity of the Wilson line v. A JIMWLK equation is derived for bar{W}_tau(v); its properties are studied. These properties are used to complete Mueller's derivation of the JIMWLK equation, though for bar{W}_tau(v) and not W_tau(alpha). They are used to derive a generalized Balitsky-Kovchegov equation for higher multipole amplitudes. They are also used to compute the unintegrated gluon distribution at x_F=0, yielding a completely flat spectrum in transverse momentum squared k^2, with a known height. This is similar but not identical to the mean field result at small k^2.Comment: One reference and two short comments added. To appear in Physical Revies

    Quantum collisions of finite-size ultrarelativistic nuclei

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    We show that the boost variable, the conjugate to the coordinate rapidity, which is associated with the center-of-mass motion, encodes the information about the finite size of colliding nuclei in a Lorentz-invariant way. The quasi-elastic forward color-changing scattering between the quantum boost states rapidly grows with the total energy of the collision and leads to an active breakdown of the color coherence at the earliest moments of the collision. The possible physical implications of this result are discussed.Comment: 23 pages, RevTeX. New references and two figures added. Final version accepted for publication in Physical Review

    Global Incidence and mortality of oesophageal cancer and their correlation with socioeconomic indicators temporal patterns and trends in 41 countries

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    Oesophageal cancers (adenocarcinomas [AC] and squamous cell carcinomas [SCC]) are characterized by high incidence/mortality in many countries. We aimed to delineate its global incidence and mortality, and studied whether socioeconomic development and its incidence rate were correlated. The age-standardized rates (ASRs) of incidence and mortality of this medical condition in 2012 for 184 nations from the GLOBOCAN database; national databases capturing incidence rates, and the WHO mortality database were examined. Their correlations with two indicators of socioeconomic development were evaluated. Joinpoint regression analysis was used to generate trends. The ratio between the ASR of AC and SCC was strongly correlated with HDI (r = 0.535 [men]; r = 0.661 [women]) and GDP (r = 0.594 [men]; r = 0.550 [women], both p < 0.001). Countries that reported the largest reduction in incidence in male included Poland (Average Annual Percent Change [AAPC] = −7.1, 95%C.I. = −12,−1.9) and Singapore (AAPC = −5.8, 95%C.I. = −9.5,−1.9), whereas for women the greatest decline was seen in Singapore (AAPC = −12.3, 95%C.I. = −17.3,−6.9) and China (AAPC = −5.6, 95%C.I. = −7.6,−3.4). The Philippines (AAPC = 4.3, 95%C.I. = 2,6.6) and Bulgaria (AAPC = 2.8, 95%C.I. = 0.5,5.1) had a significant mortality increase in men; whilst Columbia (AAPC = −6.1, 95%C.I. = −7.5,−4.6) and Slovenia (AAPC = −4.6, 95%C.I. = −7.9,−1.3) reported mortality decline in women. These findings inform individuals at increased risk for primary prevention

    Nonlinear QCD Evolution: Saturation without Unitarization

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    We consider the perturbative description of saturation based on the nonlinear QCD evolution equation of Balitsky and Kovchegov (BK). Although the nonlinear corrections lead to saturation of the scattering amplitude locally in impact parameter space, we show that they do not unitarize the total cross section. The total cross section for the scattering of a strongly interacting probe on a hadronic target is found to grow exponentially with rapidity. The origin of this violation of unitarity is the presence of long range Coulomb fields away from the saturation region. The growth of these fields with rapidity is not tempered by the nonlinearity of the BK equation.Comment: 4 pages, RevTe
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