5,165 research outputs found

    A note on the genus Tocantinsia (Pisces, Nematognathi, Auchenipteridae)

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    It is argued that the catfish described by MEES (1974) as representing a new genus and a new species of the Auchenipteridae : Tocantinsia depressa, is conspecific with Glanidium piresi A. DE MIRANDA RIBEIRO (1920) and that consequently the former is a junior synonym of the latter. However, the species does not belong in the genus Glanidium, being sufficiently distinct from all other Auchenipteridae to be retained in the separate genus Tocantinsia. Therefore, its correct name is Tocantinsia piresi (A. DE MIRANDA RIBEIRO)

    Functional poly(2-oxazoline)s by direct amidation of methyl ester side chains

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    Poly(2-alkyl/aryl-2-oxazoline)s (PAOx) are biocompatible pseudopolypeptides that have received significant interest for biomedical applications in recent years. The growing popularity of PAOx in recent years is driven by its much higher chemical versatility compared with the gold standard in this field, poly(ethylene glycol) (PEG), while having similar beneficial properties, such as stealth behavior and biocompatibility. We further expand the PAOx chemical toolbox by demonstrating a novel straightforward and highly versatile postpolymerization modification platform for the introduction of side-chain functionalities. PAOx having side chain methyl ester functionalities is demonstrated to undergo facile uncatalyzed amidation reactions with a wide range of amines, yielding the corresponding PAOx with side-chain secondary amide groups containing short aliphatic linkers as well as a range of side-chain functionalities including acid, amine, alcohol, hydrazide, and propargyl groups. The PAOx with side-chain methyl ester groups can be prepared by either partial hydrolysis of a PAOx followed by the introduction of the methyl ester via modification of the secondary amine groups with methyl succinyl chloride or by the direct copolymerization of a nonfunctional 2-oxazoline monomer with a 2-methoxycarbonylethyl-2-oxazoline. Thus, this novel synthetic platform enables direct access to a wide range of side-chain functionalities from the same methyl-ester-functionalized poly(2-oxazoline) scaffold

    Non-Linear Markov Modelling Using Canonical Variate Analysis: Forecasting Exchange Rate Volatility

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    We report on a novel forecasting method based on nonlinear Markov modelling and canonical variate analysis, and investigate the use of a prediction algorithm to forecast conditional volatility. In particular, we assess the dynamic behaviour of the model by forecasting exchange rate volatility. It is found that the nonlinear Markov model can forecast exchange rate volatility significantly better than the GARCH(1,1) model due to its flexibility in accommodating nonlinear dynamic patterns in volatility, which are not captured by the linear GARCH(1,1) model.

    Approximating the DGP of China's Quarterly GDP

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    We demonstrate that the data generating process (DGP) of China’s cumulated quarterly Gross Domestic Product (GDP, current prices), as it is reported by the National Bureau of Statistics of China, can be (very closely) approximated by a simple rule. This rule is that annual growth in any quarter is equal to annual growth in its previous quarter plus an error term that is only nonzero in the first quarter of each year and with small variance. We show that this rule fits the data for 1992Q1 to 2005Q4 well, for total GDP as well for its three sector-specific components. It also gives accurate forecasts for 2006Q1 to 2009Q4. We also study the time series properties of GDP growth in constant prices, and show that these series behave as random walks, with much larger error variance.

    Does news on real Chinese GDP growth impact stock markets?

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    Real GDP growth in China follows a random walk. Also, it has often been suggested that China “cooks its booksâ€, that is to say that governmental officials in China manipulate economic statistics such as GDP growth rate to present the outside world a rosy picture (Foreign Policy, September 3, 2009). If such unreliability is known to stock traders, news on GDP should not impact stock market fluctuations or their volatility. We test this hypothesis for 12 series with daily stock market returns for the years 2006 to and including 2009.China;Gross Domestic Product

    Growth of German dairy farms under the EU milk quota

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    We estimate determinants of growth among German dairy farms between 1997 und 2005 under the EU milk quota system. Higher milk yield per cow, more family labour, and higher milk prices increase the growth rate of growing farms, ceteris paribus. Older growing farmers tend to grow at lower rates. In line with Weiss’ findings (1999) for Austrian farms, Gibrat’s Law of relative firm growth being independent of initial firm size does not hold for our subsample of farms growing in milk production, either: the growth rate is quite high for small farms and has a minimum for farms around 325,000 kg of initial quota. For the 16% of growing farms that have more initial quota the growth rate increases up to some out-of-sample maximum. We corrected for selection bias by means of a multinomial logit model which explains the choice among different growth regimes in more detail than the well-known Heckman procedure. In our case, e.g. age impacts the choice between growth and stagnation but not between growth and exiting from milk production; crop subsidies only influence the decision between growth and exiting from milk production but not the decision between growth and decline or stagnation.Keywords: farm growth, Gibrat’s Law, milk quota, multinomial logit, selection bias, Agricultural and Food Policy, Farm Management, Land Economics/Use,
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