A new class of Shariah-compliant portfolio optimization model: diversification analysis

This study proposes a novel Shariah-compliant portfolio optimization model tested on the daily historical return of 154 Shariah-compliant securities reported by the Shariah Advisory Council of Securities Commission Malaysia from 2011 to 2020. The mathematical model employs an annual rebalancing strategy subject to a Conditional Value-at-Risk (CVaR) constraint while considering practical and Islamic trading concerns, including transaction costs, holding limits, and zakat payment. To validate the model, the optimal portfolios are compared against an Islamic benchmark index, a market index, and portfolios generated by the mean-variance model, as well as a forecast accuracy test by the Mean Absolute Percentage Error and Mean Absolute Arctangent Percentage Error. Furthermore, this study examines the inter-stock relationship within the generated portfolios using correlation and Granger causality tests to identify the diversification performance. Results show an outperformance of the model in offering portfolios with higher risk-adjusted returns under a comparably short computational time and an indication of generally well-diversified portfolios by the weak correlations between securities. The study further noted that the model is adept at risk management in addition to higher forecast accuracy during financial crises by showing remarkably fewer causal relationships during bear markets in 2011, 2014, and 2020. The findings of an inversed relationship between portfolio risk and the number of causalities between securities offer new insights into the effect of dynamic relationships between securities on portfolio diversification. In conclusion, the proposed model carries higher moral and social values than the conventional models while portraying high potential in enhancing the efficiency of asset allocation, contributing to economic diversification and the scarce literature on Islamic portfolio optimization modelling. The study also supports the substantially increasing demand for Shariah-compliant strategies following globalization and the changing demographic of the real financial world with growing priorities of social and sustainability values

Expression of key ion transporters in the gill and esophageal- gastrointestinal tract of euryhaline mozambique tilapia oreochromis mossambicus acclimated to fresh water, seawater and hypersaline water

10.1371/journal.pone.0087591PLoS ONE91-POLN

Role of prolactin in osmotic and ionic regulation of the marine form (trachurus) of the threespine stickleback, gasterosteus aculeatus l. in fresh water

The role of prolactin in osmotic and ionic regulation of the marine threespine stickleback (Gasterosteus aculeatus L., form trachurus) in fresh water has been investigated in winter (or late autumn) and spring. Sticklebacks in late autumn or early winter, when transferred from sea water to fresh water, suffered a high mortality which could be reduced by prolactin treatment. The fish also displayed a greater fall in plasma osmolality and a smaller fall in urine osmolality than late-spring fish transferred to fresh water in the same way; this seasonal difference was apparently triggered by photoperiodic changes and could be eliminated by prolactin treatment of the late-autumn or early-winter fish. Similarly, a seasonal difference exists in the histological picture of the glomeruli of late-autumn and late-spring sticklebacks, and this difference could be eliminated by prolactin treatment of the former fish. The fall in plasma osmolality in late-autumn and winter fish after transfer to fresh water was paralleled by a rapid drop in plasma sodium and chloride, which could be corrected by a single injection of prolactin given 24 hr before the transfer. Plasma potassium, however, seemed unaffected by prolactin treatment. The evidence suggests that prolactin is essential for freshwater survival of sticklebacks and that prolactin undergoes seasonal changes in secretion associated with photoperiodic changes; the secretion is minimal in the autumn and winter when the fish live in sea water or brackish water, and maximal in the spring and summer when the fish migrate to (or are in) fresh water, to breed. Thus prolactin may be involved in the freshwater migration of sticklebacks. Next, the mechanism of action of prolactin was studied. Prolactin seems to exert its effects (in fresh water) on the three recognized organs of osmotic and ionic regulation in teleosts, viz. kidneys, gills and gut. In the kidneys, prolactin increased urine flow, apparently as a result of an increased GFR. Prolactin reduced the apparent increase in intracapsular space in the glomeruli of the late-autumn and winter sticklebacks, and, consequently, increased the percentage frequency of glomeruli with no evident intracapsular space. The data are interpreted to mean that prolactin rendered glomeruli more functional or more glomeruli fully functionaland, hence, increased GFR. Since the increase in urine flow and GFR was paralleled by a decrease in urine osmolality and urine concentrations of sodium and chloride, prolactin must also increase renal tubular reabsorption of sodium and chloride (A) and/or decrease water reabsorption (B); and since the total renal loss of sodium and chloride did not appear to be significantly increased despite an increase in GFR, A must occur with or without B. Prolactin, however, apparently increased the total renal loss of potassium and did not affect the tubular potassium reabsorption, although there was a suggestion that prolactin actually decreased tubular reabsorption of potassium. In the gills (or other regions around the head), prolactin reduced the net osmotic influx of water and the net loss of sodium, chloride and C¹⁴ (from injected C¹⁴ -inulin); the latter was probably because prolactin reduced the outflux. These changes were accompanied by the behaviour of the gill mucous cells, which were increased in density by prolactin treatment, suggesting a cause-or-effect relationship. In the gut, prolactin reduced water absorption and, at the same time, seemed to reduce the freshwater drinking rate. Thus, it appears that prolactin was able to reduce or prevent osmotic flooding of sticklebacks in fresh water by reducing extrarenal osmotic influx of water and increasing renal loss of water via an increase in GFR and urine flow, and also, possibly, by reducing drinking rate and water absorption by the gut; at the same time, prolactin reduced extrarenal loss of sodium and chloride but did not apparently affect renal loss of the ions, which was small compared to the extrarenal loss. By these mechanisms, prolactin maintained plasma osmolality and sodium and chloride levels after transfer of the fish to fresh water, and, consequently, was able to promote freshwater survival of the fish in the autumn and winter.Science, Faculty ofZoology, Department ofGraduat

CHIMERIC GENE CONSTRUCTS FOR GENERATION OF FLUORESCENT TRANSGENIC ORNAMENTAL FISH

WO2000049150A1Published Applicatio

Molecular cloning and sequencing of the hormone-binding domain of Oreochromis aureus estrogen receptor gene

DNA Sequence - Journal of DNA Sequencing and Mapping56359-370DNSE

Steroid metabolism in teleost gonads: purification and identification of metabolites by high-performance liquid chromatography

Steroids576276-281STED

The hormone-binding domain of Oreochromis aureus estrogen receptor gene: Homology comparison with other steroid binding receptors

DNA Sequence - Journal of DNA Sequencing and Mapping56371-379DNSE

Isolated nucleic acids encoding a secretory signal for expression and secretion of heterologous recombinant proteins

US6733997Granted Paten

Chimeric gene constructs for generation of fluorescent transgenic ornamental fish

US20040143864A1Published Applicatio