1,117 research outputs found

    Microelectrode arrays and the use of PEG-functionalized diblock copolymer coatings

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    PEG-modified diblock copolymer surfaces have been examined for their compatibility with microelectrode array based analytical methods. The use of PEG-modified polymer surfaces on the arrays was initially problematic because the redox couples used in the experiments were adsorbed by the polymer. This led the current measured by cyclic voltammetry for the redox couple to be unstable and increase with time. However, two key findings allow the experiments to be successful. First, after multiple cyclic voltammograms the current associated with the redox couple does stabilize so that a good baseline current can be established. Second, the rate at which the current stabilizes is consistent every time a particular coated array is used. Hence, multiple analytical experiments can be conducted on an array coated with a PEG-modified diblock copolymer and the data obtained is comparable as long as the data for each experiment is collected at a consistent time point

    Nested turbo codes for the costa problem

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    Driven by applications in data-hiding, MIMO broadcast channel coding, precoding for interference cancellation, and transmitter cooperation in wireless networks, Costa coding has lately become a very active research area. In this paper, we first offer code design guidelines in terms of source- channel coding for algebraic binning. We then address practical code design based on nested lattice codes and propose nested turbo codes using turbo-like trellis-coded quantization (TCQ) for source coding and turbo trellis-coded modulation (TTCM) for channel coding. Compared to TCQ, turbo-like TCQ offers structural similarity between the source and channel coding components, leading to more efficient nesting with TTCM and better source coding performance. Due to the difference in effective dimensionality between turbo-like TCQ and TTCM, there is a performance tradeoff between these two components when they are nested together, meaning that the performance of turbo-like TCQ worsens as the TTCM code becomes stronger and vice versa. Optimization of this performance tradeoff leads to our code design that outperforms existing TCQ/TCM and TCQ/TTCM constructions and exhibits a gap of 0.94, 1.42 and 2.65 dB to the Costa capacity at 2.0, 1.0, and 0.5 bits/sample, respectively

    Hyperon Nonleptonic Weak Decays Revisited

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    We first review the current algebra - PCAC approach to nonleptonic octet baryon 14 weak decay B (\to) (B^{\prime})(\pi) amplitudes. The needed four parameters are independently determined by (\Omega \to \Xi \pi),(\Lambda K) and (\Xi ^{-}\to \Sigma ^{-}\gamma) weak decays in dispersion theory tree order. We also summarize the recent chiral perturbation theory (ChPT) version of the eight independent B (\to) (B^{\prime}\pi) weak (\Delta I) = 1/2 amplitudes containing considerably more than eight low-energy weak constants in one-loop order.Comment: 10 pages, RevTe

    Nonfactorization in Hadronic Two-body Cabibbo-favored decays of D^0 and D^+

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    With the inclusion of nonfactorized amplitudes in a scheme with Nc=3N_c=3, we have studied Cabibbo-favored decays of D0D^0 and D+D^+ into two-body hadronic states involving two isospins in the final state. We have shown that it is possible to understand the measured branching ratios and determined the sizes and signs of nonfactorized amplitudes required.Comment: 15 pages, Late

    Analysis of Two-Body Decays of Charmed Baryons Using the Quark-Diagram Scheme

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    We give a general formulation of the quark-diagram scheme for the nonleptonic weak decays of baryons. We apply it to all the decays of the antitriplet and sextet charmed baryons and express their decay amplitudes in terms of the quark-diagram amplitudes. We have also given parametrizations for the effects of final-state interactions. For SU(3) violation effects, we only parametrize those in the horizontal WW-loop quark diagrams whose contributions are solely due to SU(3)-violation effects. In the absence of all these effects, there are many relations among various decay modes. Some of the relations are valid even in the presence of final-state interactions when each decay amplitude in the relation contains only a single phase shift. All these relations provide useful frameworks to compare with future experiments and to find out the effects of final-state interactions and SU(3) symmetry violations.Comment: 28 pages, 20 Tables in landscape form, 4 figures. Main changes are: (i) some errors in the Tables and in the relations between the quark-diagram amplitudes of this paper and those of Ref.[10] are corrected, (ii) improvements are made in the presentation so that comparisons with previous works and what have been done to include SU(3) breaking and final-state interactions are more clearly stated; to appear in the Physical Review

    Sex differentiation in grayling (Salmonidae) goes through an all-male stage and is delayed in genetic males who instead grow faster.

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    Fish populations can be threatened by distorted sex ratios that arise during sex differentiation. Here we describe sex differentiation in a wild grayling (Thymallus thymallus) population that suffers from distorted sex ratios. We verified that sex determination is linked to the sex determining locus (sdY) of salmonids. This allowed us to study sex-specific gene expression and gonadal development. Sex-specific gene expression could be observed during embryogenesis and was strong around hatching. About half of the fish showed immature testes around eleven weeks after fertilization. This phenotype was mostly replaced by the "testis-to-ovary" or "ovaries" phenotypes during development. The gonads of the remaining fish stayed undifferentiated until six months after fertilization. Genetic sexing revealed that fish with undifferentiated gonads were all males, who grew larger than the genetic females during the observational period. Only 12% of the genetic males showed testicular tissue six months after fertilization. We conclude that sex differentiation starts before hatching, goes through an all-male stage for both sexes (which represents a rare case of "undifferentiated" gonochoristic species that usually go through an all-female stage), and is delayed in males. During these juvenile stages males grow faster than females instead of developing their gonads

    Formulation and evaluation of transdermal delivery system of an anti-hypertensive drug

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    oai:ojs2.japtronline.com:article/1The present study was aims to formulate and evaluate transdermal drug delivery for sustained release of an anti-hypertensive drug Captopril, it is considered as drug of choice in anti hypertensive therapy and is reported for potential administration through transdermal route. The investigation was carried out to study the effect of different proportion of ethyl cellulose and PVP a hydrophobic and hydrophilic polymer respectively. Transdermal patches were prepared using different combination of the two polymers by solvent evaporation technique. Polyvinyl alcohol was used to prepare the backing membrane and dibutyl phthalate as a plasticizer. Several Physicochemical parameter like moisture content, moisture loss, thickness, film folding endurance, tensile strength, flatness were studied. For all the formulations, in vitro drug release was studied using modified diffusion cell. Formulations with highest proportion of polyvinyl pyrolidone shows faster release whereas increasing proportion of ethyl cellulose produces a prolonged regimen of sustained drug delivery through transdermal route for a period of 24 hrs

    Effect of supplementary pollination in grapes (Vitis vinifera)

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    In the variety Bharat Early, the weight of bunch and number of berries per bunch were markedly increased by supplementary pollinations with Pearl of Csaba and Pusa Seedless pollen as compared to control. However, berry weight was not altered. Shot berries were significantly reduced by all pollen including the self as compared to control. Least number of shot berries were obtained by using Pearl of Csaba and Pusa Seedless pollen.In the variety Pusa Seedless which is allied to Thompson Seedless the bunch weight was increased by Bharat Early, Beauty Seedless and Pearl of Csaba pollen. No significant increase in the number of berries per bunch resulted, but berry size was increased by these pollen

    Dynamics of coherently pumped lasers with linearly polarized pump and generated fields

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    The influence of light polarization on the dynamics of an optically pumped single-mode laser with a homogeneously broadened four-level medium is theoretically investigated in detail. Pump and laser fields with either parallel or crossed linear polarizations are considered, as are typical in far-infrared-laser experiments. Numerical simulations reveal dramatically different dynamic behaviors for these two polarization configurations. The analysis of the model equations allows us to find the physical origin of both behaviors. In particular, the crossed-polarization configuration is shown to be effective in decoupling the pump and laser fields, thus allowing for the appearance of Lorenz-type dynamics

    Price-minimizing behaviors in response to increasing tobacco price: a cross-sectional study of students

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    Background: The public health benefits of tobacco taxation are undermined when smokers engage in price-minimising behaviours other than quitting in response to rising prices. These include switching from smoking manufactured cigarettes to cheaper alternatives such as roll your-own (RYO). Young adults are particularly sensitive to tobacco prices. Methods: 314 students at the University of Nottingham, UK completed an online survey about their current smoking behaviour and their likely responses to hypothetical increases in the price of tobacco. Results: Cessation intent was linked to price, as was the likelihood of switching to cheaper products. Although only 7% said they would quit in response to a £0.50 increase in the price of their product, 68% said they would quit if it doubled. Among manufactured cigarette smokers who would switch products if the price of cigarettes doubled, 33% said they would switch to RYO. 44% stated they would switch to e-cigarettes if combustible tobacco became unaffordable. Conclusions: Large price increases could reduce prevalence among this age group, though this effect would be potentially be undermined by young adult smokers accessing cheaper alternatives to manufactured cigarettes. The apparent viability of e-cigarettes as a price minimising substitute for smoking may be encouraging from a public health perspective
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