4,888 research outputs found

    Thermal field over Tibetan Plateau and Indian summer monsson rainfall

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    The interannual variability of the temperature anomalies over the Tibetan Plateau (25-45 °N, 75-105 °E) is examined in relation to the Indian summer monsoon rainfall (ISMR: June to September total rainfall). For this purpose, the temperature anomaly data of the central-eastern Tibetan Plateau is divided into three regions using principal component analysis and the ISMR data for the period 1957-89 have been used. It is found that the January temperature anomaly of Region 2 has a significant negative relationship (r = -0.67) with the ISMR of the subsequent season. This region is located over the northeastern part of the Tibetan Plateau, mostly in Qinghai province, including the Bayan Harr Mountain range and the Qaidam Basin. This relationship is consistent and robust during the period of analysis and can be used to predict the strength of the Indian summer monsoon in the subsequent season. It was found that the January temperature anomaly in this region was associated with a persistent winter circulation pattern over the Eurasian continent during January through to March. Finally, the variation patterns of the temperature anomalies in all three regions over the central-eastern Tibetan Plateau during extreme years of the ISMR are examined. It is concluded that the January temperature anomaly over the northeastern Tibetan Plateau can be useful in forecasting the drought and flood conditions over India, especially in predicting the monsoon rainfall over the areas lying along the monsoon trough

    Agrobacterium mediated genetic transformation and regeneration in elite rice (Oryza sativa L.) cultivar BRRI dhan56

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    Agrobacterium-mediated genetic transformation of rice (Oryza sativa L.) cultivar BRRI dhan56 was  carried out in this study. Agrobacterium tumefaciens strain LBA 4404, which harbors the plasmid pIG121  that carries the genes for ß-glucuronidase gene, served as a reporter gene in the histochemical assay and  the neomycin phosphotransferase ΙΙ (NPT ΙΙ) gene for the identification of resistance to kanamycin was  used for genetic transformation. Twenty days old embryogenic calli from mature embryos of highly  regenerating rice cultivar BRRI dhan56 were used to co-cultivate with 0.8 to 0.9 OD600 Agrobacterium  for 25 min and the cultured was continued on agar medium for this study. The transformed colonies were selected by using 50 mg/L kanamycin and 50 mg/L rifampicin and confirmed by colony PCR. The PCR  positive colonies were isolated to transform by using calli of indica rice cultivar BRRI dhan56. Putative  leaf and root segments from  plantlets obtained from transformation experiment with the plasmid pIG121  were GUS positive. Integration of the introduced gene into the genome was  demonstrated by PCR. The  maximum transformation efficiency of 32% was obtained by using 500 mg/L cefotaxime as a  bacteriostatic agent to inhibit growth of Agrobacterium. In this study, 100 µM acetosyringone in  co-cultivation medium and co-cultivation for 3 days were the optimum conditions for maximum  transformation. The expression of GUS gene revealed that the calli were successfully transformed. The  results of this study would be an effective tool for crop improvement and gene-function studies on the  model monocot plant rice. Key words: Agrobacterium, Oryza sativa L., acetosyringone, β-glucuronidase, cefotaxime, plasmid, phosphotransferase, rice, transformation. Abbreviation: GUS, β-Glucuronidase; PCR, polymerase chain reaction; MS, Murashige and Skoog; 2,4-D, 2,4-dichlorophenoxyacetic acid; MCI, callus induction medium; OD, optical density; NAA, 1-naphthaleneacetic acid; BAP, 6-benzylaminopurine. 

    Ischaemic post-conditioning protects lung from ischaemia-reperfusion injury by up-regulation of haeme oxygenase-1

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    Objective: The emergence of ischaemic post-conditioning (IPO) provides a potential method for experimentally and clinically attenuating various types of organ injuries. There has been little work, however, examining its effects in the setting of lung ischaemia reperfusion (IR). The stress protein, haeme oxygenase-1 (HO-1), has been found to exert a potent, protective role in a variety of lung injury models. In this study, we hypothesised that the induction of HO-1 by IPO plays a protective role against the deleterious effects of IR in the lung. Methods: Anaesthetised and mechanically ventilated adult Sprague-Dawley rats were randomly assigned to one of the following groups (n = 8 each): the sham-operated control group, the IR group (40 min of left-lung ischaemia and 105 min of reperfusion), the IPO group (three successive cycles of 30-s reperfusion per 30-s occlusion before restoring full perfusion) and the ZnPPIX + IPO group (ZnPPIX, an inhibitor of HO-1, was injected intra-peritoneally at 20 mg kg -1 24 h prior to the experiment and the rest of the procedures were similar to that of the IPO group). Lung injury was assessed by arterial blood gas analysis, wet-to-dry lung weight ratio and tissue histological changes. The extent of lipid peroxidation was determined by measuring plasma levels of malondialdehyde (MDA) production. Expression of HO-1 was determined by immunohistochemistry. Results: Lung IR resulted in a significant reduction of PaO 2 (data in IR, P < 0.05 vs. data in sham) and increase of lung wet-to-dry weight ratio, accompanied with increased MDA production and severe lung pathological morphological changes as well as a compensatory increase in HO-1 protein expression, as compared with sham (All P < 0.05). IPO markedly attenuated all the above pathological changes seen in the IR group and further increased HO-1 expression. Treatment with ZnPPIX abolished all the protective effects of post-conditioning. Conclusion: It may be concluded that IPO protects IR-induced lung injury via induction of HO-1. © 2009 Elsevier Ltd. All rights reserved.postprin

    The design and construction of a movable image-based rendering system and its application to multiview conferencing

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    Image-based rendering (IBR) is an promising technology for rendering photo-realistic views of scenes from a collection of densely sampled images or videos. It provides a framework for developing revolutionary virtual reality and immersive viewing systems. While there has been considerable progress recently in the capturing, storage and transmission of image-based representations, most multiple camera systems are designed to be stationary and hence their ability to cope with moving objects and dynamic environment is somewhat limited. This paper studies the design and construction of a movable image-based rendering system based on a class of dynamic representations called plenoptic videos, its associated video processing algorithms and an application to multiview audio-visual conferencing. It is constructed by mounting a linear array of 8 video cameras on an electrically controllable wheel chair and its motion is controllable manually or remotely through wireless LAN by means of additional hardware circuitry. We also developed a real-time object tracking algorithm and utilize the motion information computed to adjust continuously the azimuth or rotation angle of the movable IBR system in order to cope with a given moving object in a large environment. Due to imperfection in tracking and mechanical vibration encountered in movable systems, the videos may appear very shaky and a new video stabilization technique is proposed to overcome this problem. The usefulness of the system is illustrated by means of a multiview conferencing application using a multiview TV display. Through this pilot study, we hope to disseminate useful experience for the design and construction of movable IBR systems with improved viewing freedom and ability to cope with moving object in a large environment.published_or_final_versio

    Super-resolving phase measurements with a multi-photon entangled state

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    Using a linear optical elements and post-selection, we construct an entangled polarization state of three photons in the same spatial mode. This state is analogous to a ``photon-number path entangled state'' and can be used for super-resolving interferometry. Measuring a birefringent phase shift, we demonstrate two- and three-fold improvements in phase resolution.Comment: 4 pages, 3 figure

    Photonic waveguide engineering using pulsed lasers - A novel approach for non-clean room fabrication!

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    Over the last 25 years has seen an unprecedented increase in the growth of phonic components based on semiconductor and solid-state lasers, glass and polymer based optical fibres, and organic LEDs. Emerging technology for component engineering must embed dissimilar materials based devices into an integrated form which is more efficient. In this article, we demonstrate techniques for overcoming the materials related limitations by adopting thin-film deposition techniques based on nano- and femto-second pulsed laser deposition. Three examples of thin-film fabrication for near-IR devices using Er3+-ion doped glass-on-GaAs, Er3+-ion doped glass-polydimethyl silane (PDMS) polymer, and Tm3+-doped nano-silicon thin films and gain medium waveguides are discussed. The modelling tools are used a priori for waveguide engineering for ascertaining the extent to which the structural incompatibility due to mismatch strain can be minimized. The structure and spectroscopic properties of Er3+- ion doped thin films on silica, polymer, and semiconductor GaAs substrates were examined in detail and are reported. We demonstrate the formation of glass-polymer superlattice structures for waveguide fabrication for overcoming the solubility limits of Er3+-ions in PDMS polymers. For inscribing waveguides in superlattice structures and nano silicon structures, the ablation machining using fs-pulsed Ti-sapphire laser was used, and the resulting spectroscopic properties of waveguides are discussed.The authors acknowledge the financial support from RCUK Basic Technology project (EP/D048692/1).This is the accepted manuscript. The final version is available from IEEE at http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6876466
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