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The shape of the length frequency distribution (LFD) is an important input for stock assessments and one of the most important features in studies of fish population dynamics, providing estimates of growth parameters. In practice, oversampling may occur when sampling commercially important species. At times of more and more limited resources, the length sample size can be optimized at some stages of national or regional sampling programmes, without reducing the quality of stock assessments. The main objective of this study is to demonstrate a general distribution-free methodological approach for an optimization of sample size developed as an alternative to both analytical and bootstrap approaches. A novel framework to identify the reduced but still informative sample and to quantify the (dis) similarity between reduced and original samples is proposed. The identification procedure is based on the concept of reference subsample, which represents a theoretical minimal representative subsample that despite smaller sample size still preserves a reasonably precise LFD for certain species. The difference between the original sample and the reference subsample called admissible dissimilarity value (ADV) serves as the upper threshold and can be used to quantify the reliability of derived subsamples. Monte Carlo simulations were conducted to validate the approach under various LFD shapes. We illustrate in case studies how ADV can support to evaluate adequate sampling effort. The case studies focus on length samples from the German commercial vessels fishing for North Sea cod (Gadus morhua). [ABSTRACT FROM AUTHOR]

This paper determines the value of asset tradeability in an option pricing framework. In our model, tradeability is valuable since it allows investors to exploit temporary mispricings of stocks. The model delivers several novel insights on the value of tradeability: The value of tradeability is the larger, the higher the pricing efficiency of the market is. Uncertainty increases the value of tradeability, no matter whether the uncertainty results from noise trading or from new information about the fundamental value of the stock. The value of tradeability is the larger, the longer the illiquid stock cannot be traded and the more trading dates the liquid stock offers. [ABSTRACT FROM AUTHOR]

We introduce a new data set that comprises factor returns and returns of portfolios that are single- and double-sorted. We use this data set to perform asset-pricing tests for the German equity market. We test the standard CAPM, the Fama-French (1993) three-factor model, and the Carhart (1997) four-factor model. Our tests are based on a more comprehensive data set than are earlier studies. We investigate the sensitivity of our results to the choice of test assets. Our results indicate that none of the models can consistently explain the cross-section of returns, and that the results of asset-pricing tests are sensitive to the choice of test assets. [ABSTRACT FROM AUTHOR]

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To examine the treatment outcome for patients with acute bleeding from the lower gastrointestinal tract requiring transfusion and acute surgical care as a function of various risk factors Between 1999 and 2007, we collected data on 59 patients (39 male and 20 female patients) who received surgical intervention for acute lower intestinal hemorrhage requiring transfusion at our university clinic. Treatment complications and mortality were analyzed retrospectively. The average age of the patients in this study is 70.0 ± 12.2 years (range, 39 to 97 years) with an overall mortality of 15.3%. Blood transfusions >10 U ( p = 0.031), postoperative need for ventilation ( p = 0.004), necessary reoperations ( p = 0.016), and an initial hemoglobin level <80 g/L ( p = 0.043) proved to be significant risk factors for death. Blood transfusions >10 U ( p = 0.028), necessary reoperations ( p = 0.001), and an initial hemoglobin level <80 g/L ( p = 0.033) were found to be significant risk factors for postoperative complications. All other parameters have no significant impact. The decisive factors for the outcome of lower gastrointestinal hemorrhage requiring surgery are the severity of bleeding, beginning of treatment (initial hemoglobin level, need for packed red blood cells), and treatment efficiency (necessary reoperation). [ABSTRACT FROM AUTHOR]

According to standard portfolio theory, the tangency portfolio is the only efficient stock portfolio. However, empirical studies show that an investment in the global minimum variance portfolio often yields better out-of-sample results than does an investment in the tangency portfolio and suggest investing in the global minimum variance portfolio. But little is known about the distributions of the weights and return parameters of this portfolio. Our contribution is to determine these distributions. By doing so, we answer several important questions in asset management. [ABSTRACT FROM AUTHOR]

In this paper, we propose a theoretical continuous-time model to analyze the impact of liquidity on bond prices. This model prices illiquid bonds relative to liquid bonds and provides a testable theory of illiquidity induced price discounts. The model is tested using 1992-1994 data from bonds issued by the German government. These bonds define a market segment that is homogeneous in bankruptcy risk, taxes, age, and coupons, but the bonds differ with respect to their liquidity. The empirical findings suggest that bond prices not only depend on the dynamics of interest rates, but also on the liquidity of bonds. Therefore, bond liquidity should be used as an additional pricing factor. The findings of the out-of-sample test demonstrate the superiority of the model in comparison with traditional pricing models. [ABSTRACT FROM AUTHOR]

One virulent phage from soil lysed all tested strains of Faenia rectivirgula, whereas six others-three of them from lysogenic cultures-lysed only nonlysogenic strains. Restriction analysis showed that these six phages are closely related, although one of them is virulent and the others are temperate. Another member of this group is a Streptomyces erythraeus phage, which also lysed only the four nonlysogenic strains of F. rectivirgula. [ABSTRACT FROM AUTHOR]