A methodology to create robust job rotation schedules

This research proposes a methodology for developing robust job rotation schedules to reduce the likelihood of low back injury due to lifting. We consider settings that have uncertain task demands and different worker profiles in order to simulate real settings. We begin by considering deterministic versions of the problem and solve these using mathematical programming. Because mathematical programming cannot be readily applied to stochastic versions of the problem, heuristic solution methods are developed. The effectiveness of these methods is demonstrated by comparing the results with provably optimal solutions from the deterministic problems and with an enumerative approach that is applied to the stochastic version of the problem. Across the test problems, the proposed heuristics are effective at finding good job rotation solutions. The proposed methods could also be applied to solve other job rotation objectives such as maximizing productivity and reducing exposure to other work environmental factors such as excessive noise.     

Exogenous Spermidine Alleviates UV-Induced Growth Inhibition of Synechocystis sp. PCC 6803 via Reduction of Hydrogen Peroxide and Malonaldehyde Levels

Effects of exogenously added spermidine (Spd) to UV-treated Synechocystis sp. PCC 6803 cultures on their growth, intracellular pigments, hydrogen peroxide (H₂O₂), malonaldehyde (MDA) contents, and antioxidant enzymes were investigated. Growth inhibition of cells subjected to 1-h UV-A, UV-B, and UV-C irradiation was abolished in culture added with 0.5 mM Spd. Both chlorophyll a and carotenoid contents were decreased under UV radiations in cells grown in BG₁₁ medium. However, the contents of these two pigments were slightly increased under UV radiations in Spd-supplemented cells with the consequence of enhanced oxygen evolution. Intracellular levels of H₂O₂ and MDA generated during 1-h UV irradiation were decreased when the culture medium contained 0.5 mM Spd. The antioxidative enzymes, catalase, and superoxide dismutase had a little or no response towards Spd supplementation under UV irradiation except for some increase in superoxide dismutase activity under UV-C. Total intracellular polyamines were decreased during Spd supplementation under UV stress; however, the cells showed a drastic increase in the amount of Put under this condition. Altogether, exogenous Spd is likely a potential compound that enables Synechocystis cells to cope with UV stress.     

A Quantitative Method for Determining Proper Job Rotation Intervals

Job rotation is a useful tool that can be used in many work settings to produce task variety for workers and to reduce worker fatigue and injuries. Developing a job rotation plan requires determining the set of jobs to be included in the rotation, the rotation sequence, and the proper length of the rotation interval. Previous research has considered both the jobs to include in a rotation plan and how to sequence the rotation plan but no work has been conducted to quantitatively examine different rotation interval lengths. Using different rotation interval lengths may result in different stresses for the workers performing a particular set of tasks and therefore affect the quality of the job rotation implementation. This paper proposes a quantitative method based on mathematical programming to obtain a proper job rotation interval length. The merit of the method is determined by examining its effectiveness in reducing worker stress and the potential for injury as well as its applicability for use in real settings.     

Multiple Bioactivities of Manihot esculenta Leaves: UV Filter,Anti-Oxidation,Anti-Melanogenesis,Collagen Synthesis Enhancement,and Anti-Adipogenesis

The cassava root is an important global agro-industrial crop that yields cassava leaf as a left-over co-product of interest for further development as a sustainable resource of health and cosmeceutical active compounds. This work aimed to investigate the cosmeceutical potential and chemical composition of an ethanolic cassava leaf extract (BM). rutin, apigenin, and kaempferol were found to be major constituents via HPLC-DAD UV analysis. Interestingly, the multiple beneficial bioactivities of BM for cosmeceutical applications were manifested in a dose-dependent manner, including anti-oxidation in a 2,2-diphenyl-1-picrylhydrazyl assay, anti-melanogenesis in B16 melanoma cells, collagen synthesis enhancement in human fibroblasts, and anti-adipogenesis in 3T3-L1 adipocytes. Furthermore, the potential of the collagen synthesis enhancement of BM and rutin was significant when compared to ascorbic acid. Additionally, a UV filter property comparable to BEMT with characteristics of board spectral absorption and constant high absorptivity throughout all UV wavelength ranges was exhibited by UV-visible spectrophotometric analysis. In conclusion, the cassava leaf was found to be a potential natural cosmeceutical active agent with multiple cosmeceutical-related bioactivities with respect to a substantial composition of bioactive flavonols. These obtained data will support and encourage the further study and development of cassava leaves as potential economic and sustainable sources of bioactive agents for health and cosmeceutical applications.