Portfolio optimization in the Kenyan stock market: a comparison between mean-variance optimization and threshold accepting

A Dissertation submitted in partial fulfillment of the requirements for the Master of Science in Mathematical Finance (MSc.MF) at Strathmore UniversityThe Mean-Variance Optimization (MVO) model has been used in asset allocation problems since the inception of Modern Portfolio Theory in 1952. Several improvements and alternatives to MVO have been suggested and used since then. These include adding constraints to the traditional MVO model, using alternative risk measures and use of non risk-reward models. This study seeks to compare this risk-reward model against the Threshold Accepting model, which is a general optimization model, in portfolio selection in the Kenyan stock market to establish optimal stock portfolios to be held by investors in The Nairobi Securities Exchange (NSE). A comparison is done between the two models by measuring their performance using the following performance ratios: Sharpe Ratio, Sortino Ratio and Information Ratio using 29 stocks in the NSE from 1998 - 2016. Using portfolio performance ratios, it is concluded that the Threshold Accepting (TA) model outperforms the Mean-Variance Optimization model but the latter is observed as a more consistent model. The TA model has portfolios with generally more superior returns relative to the risk taken for the full period; however, this is not consistent over varying time estimates. This observation implies that attention should be given to the TA model rather than the classical MVO approach with the aim of improving optimal portfolio selection

MOESM4 of The structural and functional contributions of β-glucosidase-producing microbial communities to cellulose degradation in composting

Additional file 4. Additional Materials and Methods

MOESM2 of The structural and functional contributions of β-glucosidase-producing microbial communities to cellulose degradation in composting

Additional file 2: Figure S2. Differences in the abundance and expression of family 1 β-glucosidase genes from bacteria (GH1) in the natural compost and the inoculated compost

A new azaphilone from the entomopathogenic fungus <i>Hypocrella</i> sp.

<p>This report describes the isolation of a new azaphilone, designated hypocrellone A (<b>2</b>), together with five known compounds (<b>1</b>, <b>3</b>–<b>6</b>) from a submerged culture of the entomopathogenic fungus <i>Hypocrella</i> sp. (isolate WYTY-21). The absolute stereostructures of the two compounds (<b>1</b> and <b>2</b>) were elucidated based on 1D and 2D NMR spectroscopic and mass spectrometric data combined with the data from various chemical transformations. Hypocrellone A (<b>2</b>) and three (<b>3</b>–<b>6</b>) of the five known compounds were cytotoxic to hepatoma cells (cell line BEL-7404); IC₅₀ values ranged from 6.2 to 17.4 μM. At 200 μM, none of the six compounds was toxic to normal human liver cells (cell line HL-7702) or to normal human kidney epithelial cells (cell line HEK-293T).</p

Extraction, identification and antimicrobial activity of a new furanone, grifolaone A, from <i>Grifola frondosa</i>

<p>A furanone (<b>1</b>), (<i>S</i>)-methyl 2-(2-hydroxy-3,4-dimethyl-5-oxo-2,5-dihydrofuran-2-yl)acetate, was isolated from the edible mushroom <i>Grifola frondosa</i>. Mass spectrometry and NMR analyses were used to elucidate the structure of this compound, and its absolute configuration was determined using circular dichroism spectroscopy. Compound <b>1</b> exhibited specific antifungal activity against the plant pathogens, <i>Fusarium oxysporum</i>, <i>Gibberella zeae</i> and <i>Piricularia oryzae</i> and the opportunistic human pathogen, <i>Pseudallescheria boydii</i>, resulting in minimum inhibitory concentration values of 2.5, 2.5, 1.25 and 0.15 μg/mL, respectively. In contrast, the furanone showed only weak activity towards <i>Aspergillus</i> spp., <i>Candida albicans</i> and several other fungal strains tested as well as no appreciable antibacterial activity.</p