2,382 research outputs found

    Converting relational databases into object relational databases

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    This paper proposes an approach for migrating existing Relational DataBases (RDBs) into Object-Relational DataBases (ORDBs). The approach is superior to existing proposals as it can generate not only the target schema but also the data instances. The solution takes an existing RDB as input, enriches its metadata representation with required semantics, and generates an enhanced canonical data model, which captures essential characteristics of the target ORDB, and is suitable for migration. A prototype has been developed, which migrates successfully RDBs into ORDBs (Oracle 11g) based on the canonical model. The experimental results were very encouraging, demonstrating that the proposed approach is feasible, efficient and correct

    Increased regeneration efficiency of _Brassica napus_ L. cultivars Star, Westar and Cyclone from hypocotyle and cotyledonary explants

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    The comparative organogenesis of _Brassica napus_ L cultivars Cyclone, Star and Westar was studied. The cotyledonary explants gave a higher response to all the combinations of 0.5 mg/L 2,4-D and BAP (0.5, 1.0,1.5 and 2.0 mg/L} used for optimizing the conditions for callus induction. The best mean weight and mean length of callus was obtained at 0.5 mg/L 2,4-D and 1.5mg/L BAP for Star cotyledonary explants. For the complete plant regeneration the new method of exposing the explants culture to Growth regulator free medium was performed. The method was applicable to both hypocotyl and cotyledonary explants. The Shoot Induction Frequency for hypocotyl (6-34%) in the three cultivars is higher than the cotyledonary explants (3-23%). The method is speedy and almost all of the shoots and some unshooted calli (78%) form roots on the same media without prior transfer to rooting medium

    The role of basic fibroblast growth factor in the survival of rostral and caudal cells in the developing cerebral cortex of the rat: An in vitro study

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    The cerebral cortex is generated through the proliferation of the epithelium lining the lateral ventricles of the telencephalon. Although the ventricular epithelium (VE) has a uniform appearance, evidence is mounting to suggest that the VE is heterogeneous population of cells. In support of this, we have demonstrated that dissociated cell cultures prepared from rostral regions of the embryonic cortex undergo cell death whilst their caudal counterparts survive for longer periods. Furthermore, our experiments have shown that in co-cultures, caudally derived cells are able to rescue rostral sister cells. This suggests that a factor is present in caudal cortical cells that is able to promote the survival of rostral cells. Evidence from basic fibroblast growth factor (bFGF) knockout animals has shown that there is a significant reduction in the thickness of the cerebral cortex indicating that bFGF may be one such signalling molecule. In an effort to identify neurotrophic factors involved in the survival of these cortical cells, we applied a range of growth factors and neurotrophins including bFGF to rostral cultures derived from embryonic day 17 cortices. Only bFGF significantly rescued the rostral cortical cells indicating that bFGF is a candidate factor produced by caudal cells. Caudal cells treated with genistein, to block the effects of bFGF, survived for shorter period than the untreated control cultures. We have described the distribution of FGFR 1 receptor and bFGF in rostral and caudal cortical cultures using immunocytochemistry. Western blotting and in situ hybridisation. We propose that caudal cells produce bFGF which acts in an autocrine manner to maintain their survival and is also the factor likely to be affecting rostral cells in vivo

    Aspects of anther and tissue culture in Helianthus annuus L.

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    Electrocapillary Studies Of Reversible Charge Transfer V(Iii)/V(Ii) Electrode

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    Electrocapillary equation for an ideal polarized electrode based on Gibb\u27s adsorption equation is appropriately recast into experimentally measurable quantities in order to apply it to a reversible charge transfer electrode. To calculate the various parameters of the equation developed, experimental details were worked out. For the measurement of Current-time relationship of a single drop, a fast response potentiostat was built by using transistorized chopped stabilized operational amplifiers and precision components in the circuitry with proper compensation for IR-drop in the cell and the electrical double layer capacity. The analysis of I-t curves was done by taking into account the composite nature of the process involved; faradaic and non-faradaic. V(III)/V(II) reversible change transfer electrode in absence of an complexing agent was used for its complete reversibility and high cationic adsorption on the electrode. V(III) and V(II) were prepared in situ in equivalent amounts, by the electrolytic reduction of V(IV). The V(IV) concentration was controlled by photometric titration against standardized potassium permanagate solution. The drop time was taken as a measure of interfacial tension, γ , and electrocapillary curves for the pure solvent... [see PDF file for the rest of the abstract including mathematical figures and equations]
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