5,230 research outputs found
Rhizobium as a crop enhancer and biofertilizer for increased cereal production
Greater production of cereals brings forth higher production cost and pollutes the soil environment due to excessive use of chemical fertilizers. Therefore, crop scientists are exploring an alternative source namely biofertilizers which are cost effective and environment friendly. In the biofertilizer technology, Rhizobium-legume is most common and widely used in different countries. Recently, it is also found that rhizobia can make an association with graminaceous plants such as rice, wheat, maize, barley millets and other cereals some time as endophytic without forming any nodule-like structure or causing any disease symptoms. Increasing the ability of rhizobia in biofertilizer, crop enhancing activity in nonlegumes especially cereal grains would be a useful technology for increased crop yields among resource-poor farmers. Recent findings showed both more crop enhancing and biofertilizer attributes in cereal crops due to rhizobial inoculation. In addition, plant nutrients like P, K, Ca, Mg and even Fe accumulation were also observed. Therefore, further research in this area will be able to develop a sustainable biofertilizer technology for greater and environment friendly cereal production system.Key words: Biofertilizer, cereal, crop enhancer, Rhizobium, yield
Determination of genetic variability of Asian rice (Oryza sativa L.) varieties using microsatellite markers
The microsatellite or simple sequence repeat (SSR) marker analysis was done to determine the allelic diversity and relationship among thirty-five Asian cultivars of rice including 19 aromatic, 13 nonaromaticand 3 japonica type cultivars. A total of 144 alleles were detected at the 32 SSR loci, of which 141 (98%) were polymorphic. The number of alleles generated by each marker ranged from 2 to 13 with an average of 4.5 alleles per marker. The size of smallest and largest allele ranged from 8(RM122) to as high as 71 (RM302). Polymorphism information content (PIC) values ranged between 0.157 (RM19, RM55) and 0.897 (RM70), with an average of 0.603 per marker. Basmati rice varieties amplified different alleles at 15 of the SSR loci than those in the japonica and/ or indica rice varieties. A number of SSRs were identified that could be utilized to differentiate between basmati and other non-basmati rice varieties. The RM252 and RM310 showed a clear differentiation of japonica cultivarsfrom other ones. Pair-wise Nei and Li’s similarity coefficients ranged from 0.19 to 0.90. The dendrogram based on the cluster analysis by microsatellite polymorphism, grouped 35 rice cultivars into two major groups effectively differentiating the tall, late maturing and slender aromatic cultivars from the short statured, early, short bold and long bold non-aromatic cultivars. These results could be useful for monitoring purity, genotype identification and for plant variety protection
Solving multi-scale low frequency electromagnetic problems
In this paper, we will discuss two methods to tackle the low-frequency, multi-scale electromagnetics problem. First we will discuss the augmented electric field integral equation (AEFIE), and then, we will discuss the equivalence principle algorithm (EPA). The AEFIE allows the solution of such problems without the need to perform a loop search of a complex structure. The EPA allows the separation of circuit physics from wave physics in a multiscale problem. Hybridization of these two methods will be discussed.published_or_final_versionThe 4th European Conference on Antennas and Propagation (EuCAP) 2010, Barcelona, Spain, 12-16 April 2010. In Proceedings of the 4th EuCAP, 2010, p. 1-
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Young's modulus, Poisson's ratio, and residual stress and strain in (111)-oriented scandium nitride thin films on silicon
Epitaxial scandium nitride films (225 nm thick) were grown on silicon by molecular beam epitaxy, using ammonia as a reactive nitrogen source. The main crystallographic orientation of ScN with respect to Si is (111)(ScN)parallel to(111)(Si) and [1-10](ScN)parallel to[0-11](Si); however, some twinning is also present in the films. The films displayed a columnar morphology with rough surfaces, due to low adatom mobility during growth. The strain-free lattice parameter of ScN films grown under optimized conditions was found to be 4.5047 +/- 0.0005 A, as determined using high-resolution x-ray diffraction (HRXRD). In-plane and out-of-plane strains were subsequently evaluated using HRXRD and were used to determine the Poisson ratio of ScN along the direction, which is found to be 0.188 +/- 0.005. Wafer curvature measurements were made and combined with the strain information to determine the average Young's modulus of the films, which is found to be 270 +/- 25 GPa. Residual film stresses ranged from -1 to 1 GPa (depending on film growth temperature and film thickness) due to competition between the tensile stress (induced by the differential thermal contraction between the ScN film and the Si substrate) and intrinsic compressive stresses generated during growth
Fluvial biotopes influence macroinvertebrate biodiversity in South-East Asian tropical streams
This is the final version. Available from Ecological Society of America via the DOI in this record.Given the widespread degradation of aquatic systems caused by land‐use changes associated with palm oil production in South‐East Asia, it is imperative to identify and study the remaining undisturbed rivers and streams. Stream macroinvertebrates are reliable indicators of environmental health. Linking the community structure of these organisms to natural hydraulic and geomorphic conditions (categorized as biotopes) is vital for the conservation and restoration of streams. This study characterizes the effects of biotopes on macroinvertebrate community structure in three streams within Ulu Temburong National Park in northern Borneo. Biotopes within these streams were categorized as either bedrock (waterfalls and cascades) or mixed substrate (riffles and pools). In total, 119 taxa were collected from all sampled biotopes, but not all taxa were collected from each stream. Biotopes were statistically distinct in terms of taxonomic richness, but not mean individual density or average community biomass. There were differences in community structure between waterfalls, cascades, pools, and riffles. The survey suggests that pool and riffle biotopes were more vulnerable to scouring flows and had similar community structure, while waterfalls and cascades likely experienced lower sheer stress during floods and had similar macroinvertebrate communities. This study has found that classification and mapping of macroinvertebrates with biotope theory in pristine, tropical streams is a useful framework for simplifying the many linkages between ecology, geomorphology, and hydrology. These natural patterns increase our understanding of tropical streams and can be used to assess the impacts of forest degradation.Natural Environment Research Council‐funded PhD Studentshi
A catalog of Kazarian galaxies
The entire Kazarian galaxies (KG) catalog is presented which combines
extensive new measurements of their optical parameters with a literature and
database search. The measurements were made using images extracted from the
STScI Digitized Sky Survey (DSS) of Jpg(blue), Fpg(red) and Ipg(NIR) band
photographic sky survey plates obtained by the Palomar and UK Schmidt
telescopes. We provide accurate coordinates, morphological type, spectral and
activity classes, blue apparent diameters, axial ratios, position angles, red,
blue and NIR apparent magnitudes, as well as counts of neighboring objects in a
circle of radius 50 kpc from centers of KG. Special attention was paid to the
individual descriptions of the galaxies in the original Kazarian lists, which
clarified many cases of misidentifications of the objects, particularly among
interacting systems. The total number of individual Kazarian objects in the
database is now 706. We also include the redshifts which are now available for
404 galaxies and the 2MASS infrared magnitudes for 598 KG. The database also
includes extensive notes, which summarize information about the membership of
KG in different systems of galaxies, and about revised activity classes and
redshifts. An atlas of several interesting subclasses of KG is also presented.Comment: 15 pages, 5 figures, 1 table, Accepted in Astrophysics, Vol. 53, No.
1, 2010 (English translation of Astrofizika
Current-induced magnetization dynamics in Co/Cu/Co nanopillars
Author name used in this publication: S. Q. Shi2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Micromagnetic simulations of current-induced magnetization switching in Co/Cu/Co nanopillars
Author name used in this publication: S. Q. Shi2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
GPU computing of compressible flow problems by a meshless method with space-filling curves
A graphic processing unit (GPU) implementation of a meshless method for solving compressible flow problems is presented in this paper. Least-square fit is used to discretize the spatial derivatives of Euler equations and an upwind scheme is applied to estimate the flux terms. The compute unified device architecture (CUDA) C programming model is employed to efficiently and flexibly port the meshless solver from CPU to GPU. Considering the data locality of randomly distributed points, space-filling curves are adopted to re-number the points in order to improve the memory performance. Detailed evaluations are firstly carried out to assess the accuracy and conservation property of the underlying numerical method. Then the GPU accelerated flow solver is used to solve external steady flows over aerodynamic configurations. Representative results are validated through extensive comparisons with the experimental, finite volume or other available reference solutions. Performance analysis reveals that the running time cost of simulations is significantly reduced while impressive (more than an order of magnitude) speedups are achieved
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