27 research outputs found

    After-Hours Block Trading, Short Sales, And Information Leakage: Evidence From Korea

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    We investigate the impact of insider trading in after-hours block market on stock price and short sales volume, before and after the trading becomes public information. During pre-announcement period, positive (negative) abnormal stock return is generated when insiders buy (sell) their shares but does not when quasi-insiders trade, implying that stock price reflects long-lived private information of corporate governance structure. The impact is most prominent when ownership shares are transferred to (from) corporate insiders. In contrast, short sales volume generally does not depend on the identity of block holders. Short sales volume has a negative correlation with abnormal stock return only during the transaction date, indicating that a short-sale decision of tippees is based on their sole expectation on instantaneous stock returns. We also find evidence that insiders select the timing of their trades with respect to maximizing their realized profits or minimizing their purchasing costs.

    Can Derivative Information Predict Stock Price Jumps?

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    This study examines the predictability of jumps in stock prices using options-trading information, the futures basis spread, the cross-sectional standard deviation of returns on components in the stock index, and exchange rates. A stock price jump was defined as a large fluctuation in the stock price that deviated from the distribution thresholds of the past rates of return. This empirical analysis shows that the implied volatility spread between ATM call and put options was a significant predictor for both upward and downward jumps, whereas the volatility skew was less significant. In addition, the futures basis spread was moderately significant for downward stock price jumps. Both the cross-sectional standard deviation of the rates of return on component stocks in the KOSPI 200 and the won-dollar exchange rates were significant predictors for both upward and downward jumps

    Use of a Yeast tRNase Killer Toxin to Diagnose Kti12 Motifs Required for tRNA Modification by Elongator

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    Saccharomyces cerevisiae cells are killed by zymocin, a tRNase ribotoxin complex from Kluyveromyces lactis, which cleaves anticodons and inhibits protein synthesis. Zymocin’s action requires specific chemical modification of uridine bases in the anticodon wobble position (U34) by the Elongator complex (Elp1-Elp6). Hence, loss of anticodon modification in mutants lacking Elongator or related KTI (K. lactis Toxin Insensitive) genes protects against tRNA cleavage and confers resistance to the toxin. Here, we show that zymocin can be used as a tool to genetically analyse KTI12, a gene previously shown to code for an Elongator partner protein. From a kti12 mutant pool of zymocin survivors, we identify motifs in Kti12 that are functionally directly coupled to Elongator activity. In addition, shared requirement of U34 modifications for nonsense and missense tRNA suppression (SUP4; SOE1) strongly suggests that Kti12 and Elongator cooperate to assure proper tRNA functioning. We show that the Kti12 motifs are conserved in plant ortholog DRL1/ELO4 from Arabidopsis thaliana and seem to be involved in binding of cofactors (e.g., nucleotides, calmodulin). Elongator interaction defects triggered by mutations in these motifs correlate with phenotypes typical for loss of U34 modification. Thus, tRNA modification by Elongator appears to require physical contact with Kti12, and our preliminary data suggest that metabolic signals may affect proper communication between them

    Identification of a novel antiapoptotic protein that antagonizes ASK1 and CAD activities

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    Diverse stimuli initiate the activation of apoptotic signaling pathways that often causes nuclear DNA fragmentation. Here, we report a new antiapoptotic protein, a caspase-activated DNase (CAD) inhibitor that interacts with ASK1 (CIIA). CIIA, by binding to apoptosis signal-regulating kinase 1 (ASK1), inhibits oligomerization-induced ASK1 activation. CIIA also associates with CAD and inhibits the nuclease activity of CAD without affecting caspase-3–mediated ICAD cleavage. Overexpressed CIIA reduces H2O2- and tumor necrosis factor-α–induced apoptosis. CIIA antisense oligonucleotides, which abolish expression of endogenous CIIA in murine L929 cells, block the inhibitory effect of CIIA on ASK1 activation, deoxyribonucleic acid fragmentation, and apoptosis. These findings suggest that CIIA is an endogenous antagonist of both ASK1- and CAD-mediated signaling

    Share repurchase, executive options and wealth changes to stockholders and bondholders

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    We test the signaling and wealth transfer hypotheses around the announcement of share repurchases using a recent and larger sample of data than previously examined while employing a methodology designed to enhance the power of our tests. Disentangling the wealth transfer and signaling hypotheses is difficult; they are not mutually exclusive and can have opposite effects for bondholders. Wealth transfers decrease bondholder wealth while positive signals increase it; the combined result obscures tests of each hypothesis. By focusing on sub-samples where signaling is more and less likely to be present we increase our ability to isolate the separate effects. In addition to traditional tests of wealth effects, we feature information inherent in the correlation of wealth changes to equity and debt. Our results are generally consistent with the positive signaling effect of stock repurchases, but also provide some support for wealth transfer. Our work also emphasizes the importance of trying to disentangle the various hypotheses. In the subset of option funding repurchases, where signaling effects are less likely, the positive correlation of wealth changes between stockholders and bondholders is completely eliminated. Bond ratings are much more likely to be upgraded in samples without executive options which is precisely where the signaling effects are expected to be concentrated. Firms with weaker shareholder rights experience greater bondholder wealth losses at the announcement of stock repurchases.Share repurchase Executive options Wealth transfer Signaling Corporate governance Bond ratings

    MISFITSTRAIN AND GROWTH CHARACTERISTICS OF INAS/GAAS QUANTUM DOTS GROWN BY MOLECULAR BEAM EPITAXY

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    Modeling the combined effect of temperature and relative humidity on Escherichia coli O157:H7 on lettuce

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    Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699International audienceThe effect of relative humidity (RH) and temperature on the microbial behavior of Escherichia coli O157:H7 on lettuce was investigated. Experimental data obtained under different combined conditions of RH (60, 70, and 80%) and temperature (15, 25, and 35A degrees C) were fitted into the Logistic model with delay to estimate specific growth rate (SGR) with high coefficients of determination (R (2)s > 0.98). The estimated SGR values were used to develop a Gamma-concept model. Then, several statistic characteristics were employed to verify the performance and reliability of the developed model, which demonstrated that the predictive model was not biased and had high accuracy in prediction. Besides, the analysis of relative importance of temperature and RH indicated that temperature is much more influential on the growth of E. coli O157:H7 on lettuce than the ambient RH changes
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