2,243 research outputs found
The asymptotic iteration method for the angular spheroidal eigenvalues with arbitrary complex size parameter c
The asymptotic iteration method is applied, to calculate the angular
spheroidal eigenvalues with arbitrary complex size
parameter . It is shown that, the obtained numerical results of
are all in excellent agreement with the available
published data over the full range of parameter values , , and .
Some representative values of for large real are
also given.Comment: 15 pages, 1 figur
Balloon-borne coded aperture telescope for arc-minute angular resolution at hard x-ray energies
We are working on the development of a new balloon-borne telescope, MARGIE (minute-of-arc resolution gamma ray imaging experiment). It will be a coded aperture telescope designed to image hard x-rays (in various configurations) over the 20 - 600 keV range with an angular resolution approaching one arc minute. MARGIE will use one (or both) of two different detection plane technologies, each of which is capable of providing event locations with sub-mm accuracies. One such technology involves the use of cadmium zinc telluride (CZT) strip detectors. We have successfully completed a series of laboratory measurements using a prototype CZT detector with 375 micron pitch. Spatial location accuracies of better than 375 microns have been demonstrated. A second type of detection plane would be based on CsI microfiber arrays coupled to a large area silicon CCD readout array. This approach would provide spatial resolutions comparable to that of the CZT prototype. In one possible configuration, the coded mask would be 0.5 mm thick tungsten, with 0.5 mm pixels at a distance of 1.5 m from the central detector giving an angular resolution of 1 arc-minute and a fully coded field of view of 12 degrees. We review the capabilities of the MARGIE telescope and report on the status of our development efforts and our plans for a first balloon flight
Telerobotics: A simulation facility for university research
An experimental telerobotics (TR) simulation suitable for studying human operator (H.O.) performance is described. Simple manipulator pick-and-place and tracking tasks allowed quantitative comparison of a number of calligraphic display viewing conditions. A number of control modes could be compared in this TR simulation, including displacement, rate and acceleratory control using position and force joysticks. A homeomorphic controller turned out to be no better than joysticks; the adaptive properties of the H.O. can apparently permit quite good control over a variety of controller configurations and control modes. Training by optimal control example seemed helpful in preliminary experiments. An introduced communication delay was found to produce decrease in performance. In considerable part, this difficulty could be compensated for by preview control information. That neurological control of normal human movement contains a data period of 0.2 second may relate to this robustness of H.O. control to delay. The Ames-Berkeley enhanced perspective display was utilized in conjunction with an experimental helmet mounted display system (HMD) that provided stereoscopic enhanced views
Radio Astronomical Polarimetry and the Lorentz Group
In radio astronomy the polarimetric properties of radiation are often
modified during propagation and reception. Effects such as Faraday rotation,
receiver cross-talk, and differential amplification act to change the state of
polarized radiation. A general description of such transformations is useful
for the investigation of these effects and for the interpretation and
calibration of polarimetric observations. Such a description is provided by the
Lorentz group, which is intimately related to the transformation properties of
polarized radiation. In this paper the transformations that commonly arise in
radio astronomy are analyzed in the context of this group. This analysis is
then used to construct a model for the propagation and reception of radio
waves. The implications of this model for radio astronomical polarimetry are
discussed.Comment: 10 pages, accepted for publication in Astrophysical Journa
Induced Systemic Resistance (ISR) in Arabidopsis thaliana by Bacillus amyloliquefaciens and Trichoderma harzianum used as seed treatments
The Trichoderma fungal species and the bacteria Bacillus species were described as inducers of plant systemic resistance in relation to their antagonistic activity. The objective of this study was to evaluate the effect of selected strains of Bacillus amyloliquefaciens (I3) and Trichoderma harzianum (A) on inducing systemic resistance in Arabidopsis thaliana as a model for plant molecular genetics. The microorganisms were identified and were confirmed for their antagonistic potential in vitro and in vivo in previous studies. In order to explore this mechanism, two mutants of A. thaliana carrying a PR1 promoter (a conventional marker of salicylic acid (SA) pathway) and LOX2 promoter (a marker triggering jasmonic acid (JA) pathway activation) were analyzed after inoculating antagonists. Transgenic reporter line analysis demonstrated that B. amyloliquefaciens I3 and T. harzianum A induce A. thaliana defense pathways by activating SA and JA at a high level compared to lines treated with chemical elicitors of references (acibenzolar-S-methyl (Bion 50 WG (water-dispersible granule)), SA, and methyl jasmonate). The efficacy of B. amyloliquefaciens I3 and T. harzianum A in inducing the defense mechanism in A. thaliana was demonstrated in this study
A Harmonized Dataset on Global Educational Attainment between 1970 and 2060 – An Analytical Window into Recent Trends and Future Prospects in Human Capital Development
We hereby present a dataset produced at the Wittgenstein Centre (WIC) containing comprehensive time series on educational attainment and mean years of schooling (MYS). The dataset is split by 5-year age groups and sex for 171 countries and covers the period between 1970 and 2010. It also contains projections of educational attainment to 2060 based on several scenarios of demographic and educational development. The dataset is constructed around collected and harmonized empirical census and survey data sets for the projection base year. The paper presents the principles and methodology associated with the reconstruction and the projection, and how it differs from several previous exercises. It also proposes a closer look at the diffusion of education in world regions and how the existing gaps in terms of generation, gender, and geography have been evolving in the last 40 years
Molecular analysis of the TMPRSS3 gene in Moroccan families with non-syndromic hearing loss
Autosomal recessive non-syndromic hearing impairment (ARNSHI) is the most common type of inherited hearing impairment, accounting for approximately 80% of inherited prelingual hearing impairment. Hearing loss is noted to be both phenotypically and genetically heterogeneous. Mutations in the TMPRSS3 gene, which encodes a transmembrane serine protease, are known to cause autosomal recessive non-syndromic hearing impairment DFNB8/10. In order to elucidate if the TMPRSS3 gene is responsible for ARNSHI in 80 Moroccan families with non-syndromic hearing impairment, the gene was sequenced using DNA samples from these families. Nineteen TMPRSS3 variants were found, nine are located in the exons among which six are missense and three are synonymous. The 10 remaining variations are located in non-coding regions. Missense variants analysis show that they do not have a significant pathogenic effect on protein while pathogenicity of some variant remains under discussion. Thus we show that the TMPRSS3 gene is not a major contributor to non-syndromic deafness in the Moroccan population
Bihamiltonian Cohomologies and Integrable Hierarchies I: A Special Case
We present some general results on properties of the bihamiltonian
cohomologies associated to bihamiltonian structures of hydrodynamic type, and
compute the third cohomology for the bihamiltonian structure of the
dispersionless KdV hierarchy. The result of the computation enables us to prove
the existence of bihamiltonian deformations of the dispersionless KdV hierarchy
starting from any of its infinitesimal deformations.Comment: 43 pages. V2: the accepted version, to appear in Comm. Math. Phy
Efficacité de Bacillus amyloliquefaciens et Trichoderma harzianum dans le bio-contrôle de la septoriose du blé par enrobage des semences.
De notre précédente recherche d'agents de bio-contrôle de Zymoseptoria tritici agent causal de la septoriose du blé, une souche de Bacillus amyloliquefaciens et une souche de Trichoderma harzianum ont montré un haut potentiel antagoniste in vitro et in vivo, sur plants en pots sous serre, en traitement foliaire. Le présent travail avait comme objectif d'évaluer le potentiel antagoniste de ces deux souches en traitement des semences. L’enrobage des graines de deux cultivars de blé sensibles à la septoriose ("Aguilal" de blé tendre et "Karim" de blé dur), a été réalisé avec une suspension d’antagoniste qui a été préparée avec un milieu contenant 0,1% de saccharose, 1,5% de cellulose, 12% de gélatine et 10% d'argile (kaolinite et montmorillonite). Cette composition a permis la meilleure rétention de la suspension pulvérisée sur les graines.Les résultats de cet essai, ont montré que les deux antagonistes présentent un potentiel de réduction de la sévérité de la maladie sur les trois stades végétatifs (début tallage, début montaison et dernière feuille étalé) des deux cultivars de blé. La souche I3 de B. amyloliquefaciens a réduit la sévérité de la septoriose de 56% et 58% par rapport aux témoins sur Aguilal et Karim respectivement au stade dernier feuille, alors que dans le cas de T. harzianum A, ce taux était de 54% sur Aguilal et 55% sur Karim. Ces résultats suggèrent que le potentiel antagoniste serait dû à un mécanisme d’agissement à distance tel qu’une induction de la résistance systémique. Les tests de la viabilité des deux antagonistes sur les semences enrobées et stockées à 4 °C, ont montré que les deux antagonistes étaient viables après douze mois de conservation et ont préservé leurs potentiels antagonistes contre Z. tritici
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