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A rapid neutron activation analysis technique for determination of the concentration of selenium in biological materials using short-lived radionuclide 77mSe (half-life = 17.4 seconds) has been developed at Dalat Nuclear Research Institute (DNRI). The technique is very simple and rapid. It involves irradiation of a sample for 20 s, decay for 20 s and counting for 20 s. The accuracy of the method has been evaluated by analyzing a number of biological standard reference materials of varied selenium levels. An agreement between measured and certified values was acceptable in regarding to the deviation of the above mentioned two values within 8 percent. The result shows that the utilization of short-lived radionuclide 77mSe is more useful in comparison with long-lived radionuclide 75Se (half-life = 120 days). In addition, it is suggested that a further study for cyclic irradiations should be done in order to enhance the detection limit of the determination of the short-lived radionuclide 77mSe.

This paper examines the turn-of-the-year (TOY) effect in fifteen Asia Pacific stock indices by using an updated dataset. The analysis utilizes the daily datasets spanning from 2000 to 2018. Applying the Ordinary Least Square (OLS) and the Exponential Generalized Autoregressive Conditional Heteroskedastic (EGARCH) approach, the results of this paper suggest that the TOY effect becomes detectable again after the Global Financial Crisis (GFC) in developed markets with the tax year not ending in December. Furthermore, the magnitude of this anomaly diminishes in emerging markets after the GFC, which is consistent with the Efficient Market Hypothesis (EMH). The evidence of the leverage effect in the market volatility shows in negative shocks that it is considerably higher than that of positive shocks for all markets. This phenomenon is more evident in mature markets compared to emerging markets. The positive connection between the leverage effect and stock market volatility is seen with diminishing magnitude during the stable market condition after the GFC.

PurposeThis study explores the economic impact of the COVID-19 crisis on herding behaviour in the Australian equity market by considering liquidity, government interventions and sentiment contagion.Design/methodology/approachThis study utilizes a daily dataset of the top 500 stocks in the Australian market from January 2009 to December 2021. Both predictive regression and portfolio approaches are employed to consider the impact of COVID-19 on herding intention.FindingsThis study confirms that herding propensity is more pronounced at the beginning of the crisis and becomes less significant towards later phases when reverse herding is more visible. Investors herd more toward sectors with less available information on financial support from the government during the financial meltdown. Conditioning the stock liquidity, herding is only detectable during highly liquid periods and high-liquid stocks, which is more observable during the initial phases of the crisis. Further, the mood contagion from the United States (US) market to Australian market and asymmetric herding intention are evident during the pandemic.Originality/valueThis is the first study to shed further light on the impact of a health crisis on the trading behaviour of Australian investors, which is driven by liquidity, public information and sentiment. Notwithstanding the theoretical contributions to the prior literature, several practical implications are proposed for businesses, policymakers and investors during uncertainty periods.