3,464 research outputs found

    Hybridization between wild and cultivated potato species in the Peruvian Andes and biosafety implications for deployment of GM potatoes

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    The nature and extent of past and current hybridization between cultivated potato and wild relatives in nature is of interest to crop evolutionists, taxonomists, breeders and recently to molecular biologists because of the possibilities of inverse gene flow in the deployment of genetically-modified (GM) crops. This research proves that natural hybridization occurs in areas of potato diversity in the Andes, the possibilities for survival of these new hybrids, and shows a possible way forward in case of GM potatoes should prove advantageous in such areas

    Subnanosecond spectral diffusion measurement using photon correlation

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    Spectral diffusion is a result of random spectral jumps of a narrow line as a result of a fluctuating environment. It is an important issue in spectroscopy, because the observed spectral broadening prevents access to the intrinsic line properties. However, its characteristic parameters provide local information on the environment of a light emitter embedded in a solid matrix, or moving within a fluid, leading to numerous applications in physics and biology. We present a new experimental technique for measuring spectral diffusion based on photon correlations within a spectral line. Autocorrelation on half of the line and cross-correlation between the two halves give a quantitative value of the spectral diffusion time, with a resolution only limited by the correlation set-up. We have measured spectral diffusion of the photoluminescence of a single light emitter with a time resolution of 90 ps, exceeding by four orders of magnitude the best resolution reported to date

    Bosonic excitations of the AdS4 Reissner-Nordstrom black hole

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    We study the long-lived modes of the charge density and energy density correlators in the strongly-coupled, finite density field theory dual to the AdS4 Reissner-Nordstrom black hole. For small momenta q<<\mu, these correlators contain a pole due to sound propagation, as well as a pole due to a long-lived, purely imaginary mode analogous to the \mu=0 hydrodynamic charge diffusion mode. As the temperature is raised in the range T\lesssim\mu, the sound attenuation shows no significant temperature dependence. When T\gtrsim\mu, it quickly approaches the \mu=0 hydrodynamic result where it decreases like 1/T. It does not share any of the temperature-dependent properties of the 'zero sound' of Landau Fermi liquids observed in the strongly-coupled D3/D7 field theory. For such small momenta, the energy density spectral function is dominated by the sound mode at all temperatures, whereas the charge density spectral function undergoes a crossover from being dominated by the sound mode at low temperatures to being dominated by the diffusion mode when T \mu^2/q. This crossover occurs due to the changing residue at each pole. We also compute the momentum dependence of these spectral functions and their corresponding long-lived poles at fixed, low temperatures T<<\mu.Comment: 33 pages, 21 figures, 6 animation

    THE ANTIOXIDANT AND ANTIMICROBIAL ACTIVITY OF THE LEAVES EXTRACT OF CLERODENDRUM COLEBROOKIANUM WALP, (FAM: VERBENACEAE)

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    Objective: To investigate the in-vitro antioxidant and antimicrobial potential of Clerodendrum colebrookianum leaves extract.Methods: The leaves of C. colebrookianum were collected from various parts of Aizawl, Mizoram, India. Subsequently, the leaves were extracted with solvents (chloroform, acetone, ethanol and methanol) in a Soxhlet extraction apparatus for 24hr. Further, the extracts were extensively examined for its in-vitro antioxidant (DPPH) and antimicrobial activities. The preliminary phytochemical screening was carried out using standard protocols.Results: The existence of alkaloids, flavonoids, diterpenes, saponins, glycosides, steroids and terpeinoids were revealed in the phytochemical screening. The aqueous and acetone extract had the highest total phenolic content (2.348 mg/ml), when compared to methanol, ethanol and chloroform extracts, which was 0.549 mg/ml, 0.408 mg/ml and 0.407 mg/ml, respectively. The antioxidant activity was more significant for aqueous extract, when compared to other extracts. The antimicrobial activity was more significant for acetone extract showed significant zone of inhibition of 14±0.3, 13±0.3 and 15±0.2 for E. coli, S. marcescens and S. aureus, respectively.Conclusion: The high level of antioxidant and antimicrobial potential of C. colebrookianum leaf extracts encourage its potential use for biomedical applications

    Kinetic Characterisation of a Single Chain Antibody against the Hormone Abscisic Acid: Comparison with Its Parental Monoclonal

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    A single-chain Fv fragment antibody (scFv) specific for the plant hormone abscisic acid (ABA) has been expressed in the bacterium Escherichia coli as a fusion protein. The kinetics of ABA binding have been measured using surface plasmon resonance spectrometry (BIAcore 2000) using surface and solution assays. Care was taken to calculate the concentration of active protein in each sample using initial rate measurements under conditions of partial mass transport limitation. The fusion product, parental monoclonal antibody and the free scFv all have low nanomolar affinity constants, but there is a lower dissociation rate constant for the parental monoclonal resulting in a three-fold greater affinity. Analogue specificity was tested and structure-activity binding preferences measured. The biologically-active (+)-ABA enantiomer is recognised with an affinity three orders of magnitude higher than the inactive (-)-ABA. Metabolites of ABA including phaseic acid, dihydrophaseic acid and deoxy-ABA have affinities over 100-fold lower than that for (+)-ABA. These properties of the scFv make it suitable as a sensor domain in bioreporters specific for the naturally occurring form of ABA

    Premature adult mortality in urban Zambia: a repeated population-based cross-sectional study.

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    OBJECTIVES: To measure the sex-specific and community-specific mortality rates for adults in Lusaka, Zambia, and to identify potential individual-level, household-level and community-level correlates of premature mortality. We conducted 12 survey rounds of a population-based cross-sectional study between 2004 and 2011, and collected data via a structured interview with a household head. SETTING: Households in Lusaka District, Zambia, 2004-2011. PARTICIPANTS: 43,064 household heads (88% female) who enumerated 123,807 adult household members aged between 15 and 60 years. PRIMARY OUTCOME: Premature adult mortality. RESULTS: The overall mortality rate was 16.2/1000 person-years for men and 12.3/1000 person-years for women. The conditional probability of dying between age 15 and 60 (45q15) was 0.626 for men and 0.537 for women. The top three causes of death for men and women were infectious in origin (ie, tuberculosis, HIV and malaria). We observed an over twofold variation of mortality rates between communities. The mortality rate was 1.98 times higher (95% CI 1.57 to 2.51) in households where a family member required nursing care, 1.44 times higher (95% CI 1.22 to 1.71) during the cool dry season, and 1.28 times higher (95% CI 1.06 to 1.54) in communities with low-cost housing. CONCLUSIONS: To meet Zambia's development goals, further investigation is needed into the factors associated with adult mortality. Mortality can potentially be reduced through focus on high-need households and communities, and improved infectious disease prevention and treatment services
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