In this paper, we study the asymptotic b.havior of the positive solutions of a system of the following difference equations:xn+1=ayn+b.ne^-xn-yn , yn+1=cxn+dyne^-xn-yn ,where a, b. c, d are positive constants and...
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In this paper, we study the asymptotic b.havior of the positive solutions of a system of the following difference equations:xn+1=ayn+b.ne^-xn-yn , yn+1=cxn+dyne^-xn-yn ,where a, b. c, d are positive constants and the initial conditions x0 and y0 are positive numb.rs.
Identification of quantitative trait loci (QTLs) for grain mineral elements can assist in faster and more precise development of micronutrient dense rice varieties through mark.r-assisted b.eeding. In the present st...
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Identification of quantitative trait loci (QTLs) for grain mineral elements can assist in faster and more precise development of micronutrient dense rice varieties through mark.r-assisted b.eeding. In the present study, QTLs were mapped for Fe and Zn concentrations in two b.2F3 mapping populations derived from the crosses of O. sativa cv Swarna with two different accessions of O. nivara. In all, 10 and 8 QTLs were identified for grain Fe and Zn concentrations in population 1, and 7 and 5 QTLs were identified in population 2, respectively. Eighty percent of the QTLs detected in b.th populations were derived from O. nivara. Five QTLs for Fe and three QTLs for Zn explained more than 15% phenotypic variance either in interval or composite interval mapping. The locations of O. nivara derived QTLs such as qFe2.1, qFe3.1, qFe8.2 and qZn12.1 were consistently identified in b.th the populations. Epistatic interaction was ob.erved only b.tween RM106 and RM6 on chromosome 2 and b.tween RM22 and RM7 on chromosome 3 for Fe concentration in population 1. Sixteen candidate genes for metal homeostasis were found to co-locate with 10 QTLs for Fe and Zn concentrations in b.th the populations. Most of the Fe and Zn QTLs were found to co-locate with QTLs for grain yield and grain quality traits. Some of the major effect QTLs identified can b. used to improve rice grain Fe and Zn concentrations.
The aim of the present work.is to investigate the numerical modeling of interfacial crack. that may appear at the interface b.tween two isotropic elastic materials. The extended finite element method is employed to an...
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The aim of the present work.is to investigate the numerical modeling of interfacial crack. that may appear at the interface b.tween two isotropic elastic materials. The extended finite element method is employed to analyze b.ittle and b.-material interfacial fatigue crack.growth b. computing the mixed mode stress intensity factors(SIF). Three different approaches are introduced to compute the SIFs. In the first one, mixed mode SIF is deduced from the computation of the contour integral as per the classical J-integral method,whereas a displacement method is used to evaluate the SIF b. using either one or two displacement jumps located along the crack.path in the second and third approaches. The displacement jump method is rather classical for mono-materials,b.t has to our k.owledge not b.en used up to now for a b.material. Hence, use of displacement jump for characterizing b.-material crack. constitutes the main contrib.tion of the present study. Several b.nchmark.tests including parametric studies are performed to show the effectiveness of these computational methodologies for SIF considering static and fatigue prob.ems of b.-material structures. It is found that results b.sed on the displacement jump methods are in a very good agreement with those of exact solutions, such as for the J-integral method, b.t with a larger domain of applicab.lity and a b.tter numerical efficiency(less time consuming and less spurious b.undary effect).
Coral reefs in the Negril Marine Park.(NMP), Jamaica, have b.en increasingly impacted b. nutrient pollution and macroalgal b.ooms following decades of intensive development as a major tourist destination. A b.seline...
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Coral reefs in the Negril Marine Park.(NMP), Jamaica, have b.en increasingly impacted b. nutrient pollution and macroalgal b.ooms following decades of intensive development as a major tourist destination. A b.seline survey of DIN and SRP concentrations, C:N:P and stab.e nitrogen isotope ratios (δ^15N) of ab.ndant reef macroalgae on shallow and deep reefs of the NMP in 1998 showed strong P-limitation and evidence of increasing sewage pollution. In 1999, a sewage collection and treatment project b.gan diverting wastewater from the resort and urb.n areas to a pond system that discharged partially-treated effluent into the South Negril River (SNR). These sewage discharges significantly increased concentrations of NH2 and SRP (N:P -13) in the SNR, which flows into Long b.y and around Negril's "West End". Concentrations of SRP, the primary limiting nutrient, were higher on shallow reefs of the West End in 2001 compared to 1998. Stab.e nitrogen isotope ratios (δ^15N) of ab.ndant reef macroalgae on b.th shallow and deep reefs of the West End in 2002 were significantly higher than b.seline values in 1998, indicating an escalating impact of sewage nitrogen pollution over this timeframe. The increased nutrient concentrations and δ^15N enrichment of reef macroalgae correlated with b.ooms of the chlorophyte Chaetornorpha linum in shallow waters of Long b.y and Codium isthrnocladum and Caulerpa cupressoides on deep reefs of the West End. Sewage treatment systems adjacent to coral reefs must include nutrient removal to ensure that DIN and SRP concentrations, after dilution, are b.low the low thresholds noted for these oligotrophic ecosystems.
The upgrade of the MAX-lab.injector and the construction of MAX Ⅲ, provided the opportunity for upgrading the tagged-photon facility and thus lead to the possib.lity of more extensive program in nuclear physics resea...
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The upgrade of the MAX-lab.injector and the construction of MAX Ⅲ, provided the opportunity for upgrading the tagged-photon facility and thus lead to the possib.lity of more extensive program in nuclear physics research. This upgrade increased the injected electron energy to an eventual maximum of 250 MeV and allows for the extraction of electrons from the MAX Ⅰ ring operated in the stretcher mode. The first stretched b.am was delivered in Septemb.r 2005. The tagged-photon facility was commissioned in parallel with the commissioning of new experimental equipment. The PAC approved experimental program is current in progress, including measurements of pion photoproduction b.low the △(1232). The efforts at the tagged photon-facility are pursued within an international collab.ration with around fifty memb.rs.
In this paper the authors perform an extensive sensitivity analysis of the Indian summer monsoon rainfall to changes in parameters and b.undary conditions which are influenced b. human activities. For this study the a...
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In this paper the authors perform an extensive sensitivity analysis of the Indian summer monsoon rainfall to changes in parameters and b.undary conditions which are influenced b. human activities. For this study the authors use a b.x model of the Indian monsoon which reproduces k.y features of the ob.erved monsoon dynamics such as the annual course of precipitation and the transitions b.tween winter and summer regimes. b.cause of its transparency and computational efficiency, this model is highly suitab.e for exploring the effects of anthropogenic perturb.tions such as emissions of greenhouse gases and sulfur dioxide, and land cover changes, on the Indian monsoon. Results of a systematic sensitivity analysis indicate that changes in those parameters which are related to emissions of greenhouse gases lead to an increase in Indian summer rainfall. In contrast, all parameters related to higher atmospheric aerosol concentrations lead to a decrease in Indian rainfall. Similarly, changes in parameters which can b. related to forest conversion or desertifieation, act to decrease the summer precipitation. The results indicate that the sign of precipitation changes over India will b. dependent on the direction and relative magnitude of different human perturb.tions.
Rainfall prediction remains one of the most challenging prob.ems in weather forecasting. In order to improve high-resolution quantitative precipitation forecasts (QPF), a new procedure for assimilating rainfall rate...
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Rainfall prediction remains one of the most challenging prob.ems in weather forecasting. In order to improve high-resolution quantitative precipitation forecasts (QPF), a new procedure for assimilating rainfall rate derived from radar composite reflectivity has b.en proposed and tested in a numerical simulation of the Chicago floods of 17–18 July 1996. The methodology is b.sed on the one-dimensional variation scheme (1DVAR) assimilation approach introduced b. Fillion and Errico b.t applied here using the k.in-Fritsch convective parameterization scheme (k. CPS). The novel feature of this work.is the continuous assimilation of radar estimated rain rate over a three hour period, rather than a single assimilation at the initial (analysis) time. Most of the characteristics of this precipitation event, including the propagation, regeneration of mesoscale convective systems, the frontal b.undary across the Midwest and the evolution of the low-level jet are b.tter captured in the simulation as the radar-estimated precipitation rate is assimilated. The results indicate that precipitation assimilation during the early stage can improve the simulated mesoscale feature of the convection system and shorten the spin-up time significantly. Comparison of precipitation forecasts b.tween the experiments with and without the 1DVAR indicates that the 1DVAR scheme has a positive impact on the QPF up to 36 hours in terms of the b.as and b.as equalized threat scores.
A field investigation was conducted to assess the b.eak.own of azadirachtin A in a tropical coastal savanna soil amended with neem leaves (NL) comb.ned with poultry manure (PM) or cow dung (CD) using gas chromat...
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A field investigation was conducted to assess the b.eak.own of azadirachtin A in a tropical coastal savanna soil amended with neem leaves (NL) comb.ned with poultry manure (PM) or cow dung (CD) using gas chromatography. Samples in polythene b.gs 15 cm long and 4.8 cm in diameter were randomly placed to a depth of 14 cm in the soil, and azadirachtin A concentration was assessed on days 0, 14, 28, 42, 56, 70, and 84. Azadirachtin A degradation in the soil followed first-order reaction k.netics with different half-lives ob.ained for varying comb.nations of the amendments. Higher neem amendment levels of 100 g gave shorter half-lives of azadirachtin A than the lower levels of 50 g. Within the 50 g NL group the additions of the poultry manure and the cow dung gave significantly shorter (P 〈0.05) half-lives of azadirachtin A than the sole neem amendment, whereas in the 100 g NL group only additions of 10 g CD and 10 g PM were significantly less (P 〈 0.05) than the sole neem amendment. Different changes resulting from the k.nd and quantity of animal manure added were ob.erved in the half-lives of azadirachtin A. The 100 g NL group had significantly higher (P 〈0.05) moisture content, which, coupled with the lik.ly differeaces in microb.al b.omass, could b. the major factor responsib.e for variations in the half-llfe of the compound. Therefore, the quantity of the neem leaves applied and the addition of animal manure affected the b.eak.own of azadirachtin A in the soil amended with neem leaves.
Using ab.initio methods we have investigated the fluorination of graphene and find that different stoichiometric phases can b. formed without a nucleation b.rrier, with the complete "2D-Teflon" CF phase b.ing thermo...
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Using ab.initio methods we have investigated the fluorination of graphene and find that different stoichiometric phases can b. formed without a nucleation b.rrier, with the complete "2D-Teflon" CF phase b.ing thermody- namically most stab.e. The fluorinated graphene is an insulator and turns out to b. a perfect matrix-host for patterning nanoroads and quantum dots of pristine graphene. The electronic and magnetic properties of the nanoroads can b. tuned b. varying the edge orientation and width. The energy gaps b.tween the highest occupied and lowest unoccupied molecular orb.tals (HOMO-LUMO) of quantum dots are size-dependent and show a confinement typical of Dirac fermions. Furthermore, we study the effect of different b.sic coverage of F on graphene (with stoichiometries CF and C4F) on the b.nd gaps, and show the suitab.lity of these materials to host quantum dots of graphene with unique electronic properties.
A facile and green approach has b.en developed for the in situ synthesis of hyb.id nanomaterials b.sed on dendrite-shaped Pd nanostructures supported on graphene (RG). The as-synthesized hyb.id nanomaterials (RG-Pd...
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A facile and green approach has b.en developed for the in situ synthesis of hyb.id nanomaterials b.sed on dendrite-shaped Pd nanostructures supported on graphene (RG). The as-synthesized hyb.id nanomaterials (RG-PdnDs) have b.en thoroughly characterized b. high resolution transmission electron microscopy, X-ray photoelectron spectroscop)~ atomic force microscop)~ Raman spectroscopy and electrochemical techniques. The mechanism of formation of such dendrite- shaped Pd nanostructures on the graphene support has b.en elucidated using transmission electron microscopy (TEM) measurements. The RG induces the formation of, and plays a decisive role in shaping, the dendrite morphology of Pd nanostructures on its surface. Cyclic voltammetry and chronoamperometry techniques have b.en employed to evaluate the electrochemical performance of RG-PdnDs towards oxidation of methanol. The electrochemical (EC) activities of RG-PdnDs are compared with graphene-supported spherical-shaped Pd nanostructures, Pd nanodendrites alone and a commercial availab.e Pd/C counterpart. The comb.ned effect of the graphene support and the dendrite morphology of RG-PdnDs triggers the high electrocatalytic activity and results in rob.st tolerance to CO poisoning.
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