3,256 research outputs found

    A novel expression cassette for the efficient visual selection of transformed tissues in florists' chrysanthemum (Chrysanthemum morifolium Ramat.).

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    Constructs carrying visual reporter genes coupled with efficient promoters could facilitate the process of identification and selection of stable transformants in recalcitrant crops. Here, a novel construct utilizing a ribulose-1,5-bisphosphate carboxylase (RbcS) promoter combined with the green fluorescent protein (GFP) reporter gene to initiate very high expression of GFP in florist's chrysanthemum (Chrysanthemum morifolium Ramat.) was described. Based on this expression cassette, a new regeneration protocol using leaf discs as explants was developed for the Agrobacterium-mediated transformation of Chrysanthemum genotype ‘1581’, and a transformation efficiency of 7% was obtained. The expression of two different GFP constructs targeted to either cytosol or plastids was compared in transgenic lines. Both GFP constructs were expressed at such a high level that the green fluorescence dominated red fluorescence in the leaf tissues, allowing easy observation and microdissection of transformed tissues even without a GFP filter. Under normal light, plants with GFP targeted to plastids had a light green phenotype deriving from the high GFP expression. Quantitative reverse transcriptional PCR analysis showed that the plastid targeted construct with intron had significantly higher steady state transcript levels of GFP mRNA. This novel expression cassette may allow direct visual selection of transformed tissues independent of antibiotic selection in a wide range of plant specie

    Two-fluid oscillatory flow in a channel

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    AbstractThe validity of Navier's partial slip condition is investigated by studying the oscillatory flow in a coated channel. The two-fluid model is used to solve the unsteady viscous equations exactly. Partial slip is experienced by the core fluid. It is found that Naviers condition does not hold for an unsteady core fluid

    Semiparametric Approaches for Joint modeling of Longitudinal and Survival Data with Time Varying Coefficients

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    We study joint modeling of survival and longitudinal data. There are two regression models of interest. The primary model is for survival outcomes, which are assumed to follow a time varying coefficient proportional hazards model. The second model is for longitudinal data, which are assumed to follow a random effects model. Based on the trajectory of a subject\u27s longitudinal data, some covariates in the survival model are functions of the unobserved random effects. Estimated random effects are generally different from the unobserved random effects and hence this leads to covariate measurement error. To deal with covariate measurement error, we propose a local corrected score estimator and a local conditional score estimator. Both approaches are semiparametric methods in the sense that there is no distributional assumption needed for the underlying true covariates. The estimators are shown to be consistent and asymptotically normal. Finite sample properties are assessed via simulation. The approaches are demonstrated by an application to data from an HIV clinical trial

    Optimization and Form-finding of the Heavy Cable Suspending a Deck

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    The heavy spanning cable supporting a uniform deck is important in the design of suspension bridges. The analytic design method is presented in this paper. The problem depends on three non-dimensional parameters: the ratio of cable length to the horizontal spanning distance, the ratio of vertical to horizontal distance, and the ratio of deck density to cable density. Given these parameters, useful tables of maximum tension and sag are determined. There exists an optimum cable length for which the maximum tension is minimized. In addition, it is shown that continuous loads and discrete loads are equivalent if the number of evenly-spaced discrete loads are more than 10.   &nbsp

    Quasi-optical gyrotron with arbitrary beam injection angle

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    Amorphous Al-transition Metal Alloys as Anode Material for Lithium Ion Battery

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    Al based alloy powders (Al₈₅Ni₅Y₆Co₂Fe₂) are produced by spray atomization method. High energy ball milling is done to modify the surface topology and particle size for better electrochemical performance. X ray diffraction (XRD), differential scanning calorimeter (DSC), scanning electron microscope (SEM) and transmission electron microscope (TEM) were conducted to characterize the microstructure of the alloys after ball milling. It is found that 5 hours ball milling gives the minimum crystallization and structure change. Thin film sample is also deposited on stainless steel substrate by pulsed laser deposition (PLD) method for electrochemical test. The capacity and reversibility for different samples are compared and discussed. A capacity of 200mAh/g is obtained for the battery with thin film sample as anode and a capacity of 140mAh/g is obtained for that with electrode from powder sample. Both of the batteries give up to 94% capacity retention after 20 cycles.Singapore-MIT Alliance (SMA

    Chiral Vibrational Structures of Proteins at Interfaces Probed by Sum Frequency Generation Spectroscopy

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    We review the recent development of chiral sum frequency generation (SFG) spectroscopy and its applications to study chiral vibrational structures at interfaces. This review summarizes observations of chiral SFG signals from various molecular systems and describes the molecular origins of chiral SFG response. It focuses on the chiral vibrational structures of proteins and presents the chiral SFG spectra of proteins at interfaces in the C-H stretch, amide I, and N-H stretch regions. In particular, a combination of chiral amide I and N-H stretches of the peptide backbone provides highly characteristic vibrational signatures, unique to various secondary structures, which demonstrate the capacity of chiral SFG spectroscopy to distinguish protein secondary structures at interfaces. On the basis of these recent developments, we further discuss the advantages of chiral SFG spectroscopy and its potential application in various fields of science and technology. We conclude that chiral SFG spectroscopy can be a new approach to probe chiral vibrational structures of protein at interfaces, providing structural and dynamic information to study in situ and in real time protein structures and dynamics at interfaces

    ENVIRONMENTAL SURROUNDINGS AND PERSONAL WELL-BEING IN URBAN CHINA

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    We examine the relationship between atmospheric pollution, water pollution, traffic congestion, access to parkland and personal well-being using a survey administered across six Chinese cities in 2007. In contrast to existing studies of the determinants of well-being by economists, which have typically employed single item indicators to measure well-being, we use the Personal Well-Being Index (PWI). We also employ the Job Satisfaction Survey (JSS) to measure job satisfaction, which is one of the variables for which we control when examining the relationship between environmental surroundings and personal well-being. Previous research by psychologists has shown the PWI and JSS to have good psychometric properties in western and Chinese samples. A robust finding is that in cities with higher levels of atmospheric pollution and traffic congestion, respondents report lower levels of personal well-being ceteris paribus. We find that a one standard deviation increase in suspended particles or sulphur dioxide emissions is roughly equivalent to a 12-13 percent reduction in average monthly income in the six cities. This result suggests that the personal well-being of China's urban population can be enhanced if China were to pursue a more balanced growth path which curtailed atmospheric pollution.China, Environment, Pollution, Personal Well-Being.

    Learning and the Disappearing Association Between Governance and Returns

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    In an important and influential work, Gompers, Ishii, and Metrick (2003) show that a trading strategy based on an index of 24 governance provisions (G-Index) would have earned abnormal returns during the 1991-1999 period, and this intriguing finding has attracted much attention ever since it was reported. We show that the G-Index (as well as the E-Index based on a subset of the six provisions that matter the most) was no longer associated with abnormal returns during the period of 2000-2008, or any sub- periods within it, and we provide evidence consistent with the hypothesis that the disappearance of the governance-returns association was due to market participants’ learning to appreciate the difference between firms scoring well and poorly on the governance indices. Consistent with the learning hypothesis, we document that (i) attention to corporate governance from the media, institutional investors, and researchers has exploded in the beginning of the 2000s and remained on a high level since then, and (ii) until the beginning of the 2000s, but not subsequently, market participants were more positively surprised by the earning announcements of good-governance firms than by those of poor-governance firms. Our results are robust to excluding new economy firms or to focusing solely on firms in non- competitive industries. While the G and E indices could no longer generate abnormal returns in the 2000s, their negative association with Tobin’s Q persists and they thus remain valuable tools for researchers, policymakers, and investors.
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