19672 research outputs found
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Assessment of Stochastic Operation Optimization for Reservoirs of Contrasting Scales
No full textDeriving optimal release policies for dams and corresponding reservoirs is crucial for the sustainable water resources management of a region as they directly control the distribution of water to several users. Mathematical optimization algorithms can help in finding efficient reservoir operating strategies taking into account complex system constraints and hydrologic uncertainty. The robustness of operation optimization models may be influenced by physical reservoir characteristics such as size and scale and the effectiveness of a model for a particular case study does not always guarantee the same level of success for another application. This research focused on assessing the applicability of an implicit stochastic optimization (ISO) procedure to derive rule curves for two different dams of contrasting reservoir scales in terms of physical and operational characteristics. The results demonstrated the feasibility of the proposed technique for both small- and large-scale systems in view of the lower vulnerability provided by the ISO-derived policies in contrast to operations carried out by the standard reservoir operating policy as well as the proximity of the ISO operations with those by perfect-forecast deterministic optimization. The ISO procedure also provided operating rules similar to, and even less vulnerable than, those derived by stochastic dynamic programming
DNA barcoding relates Trichuris species from a human and a man’s best friend to non-human primate sources
No full textTrichuris trichiura, the whipworm of humans, is one of the most prevalent soil-transmitted helminths (STH) reported worldwide. According to a recent study, out of 289 STH studies in Southeast Asia, only three studies used molecular methods. Hence, the genetic assemblages of Trichuris in Southeast Asia are poorly understood. In this study, we used partial mitochondrial DNA (cytochrome c oxidase subunit 1 or COI) sequences for analysis. Trichuris grouped in a same clade with different hosts indicate the potential of cross infection between hosts. Based on COI, the adult Trichuris isolated from a Malaysian patient was most closely related to Trichuris isolated from Papio anubis (olive baboons) from the USA. The Trichuris isolated from the dog from Malaysia was genetically similar to a Trichuris species isolated from Macaca silenus (lion-tailed macaque) from Czech Republic. Both the human and dog isolated Trichuris grouped in clades with different hosts indicating the potential of cross infection between hosts. Specific PCR primers based on the partial COI of T. trichiura isolated from African green monkey and T. serrata were designed and successfully amplified using multiplex PCR of the pooled DNA samples. Our results suggest a complex parasite-host relationship, and support the theory of cross infection of Trichuris between humans and non-human primates as suggested in previous publications
Regulating human stem cell research and therapy in low- and middle-income countries: Malaysian perspectives
No full textMany “rising powers” such as India, China, Argentina, Singapore, and Brazil are investing in stem cell technology, joining the traditional leaders in the field, such as the UK, Germany, USA, and Japan. Malaysia is also entering this sector because of the potential medical and economic benefits that the use of stem cell technologies could provide. Like other countries, Malaysia faces the challenge of how to encourage scientific progress and innovation in an ethical manner while at the same time ensuring a safe and accessible market for regenerative therapies. This paper reports on the research findings of semi-structured interviews with local stakeholders to investigate how they perceived and evaluated the current regulatory framework for human stem cell research in Malaysia, and what might be at stake if the state continues with its current regulatory approach
Electronic and Magnetic Investigations of Rare-Earth Tm-doped AlGaN Ternary Alloy
No full textElectronic structure and magnetic interaction of substitutional thulium rare earth-doped wurtzite Al0.5Ga0.5N ternary alloy have been performed using density-functional theory within local spin-density approximation with Hubbard-U corrections (LSDA+U) approach. The LSDA+U method is applied to the rare earth (RE) 4f states. The calculation of formation energy shows that it is more energetically favorable for a substitutional Tm atom to replace the Al atom than the Ga atom. For AlGaN:Tm, the lattices parameters are expanded due to larger ionic radius of Tm than that of Al atoms. The energy band gap of AlGaN:Tm has direct character and its width becomes small compared with that of AlGaN. The magnetic coupling between Tm ions in the nearest neighbor sites is ferromagnetic. Magnetic interaction of rare earth ion with the host states at the valence and conduction band edges has been investigated and compared to those of GaN:Mn and has been found to be relatively small
Internet use by older adults with bipolar disorder: international survey results
No full textBackground: The world population is aging and the number of older adults with bipolar disorder is increasing. Digital technologies are viewed as a framework to improve care of older adults with bipolar disorder. This analysis quantifies Internet use by older adults with bipolar disorder as part of a larger survey project about information seeking. Methods: A paper-based survey about information seeking by patients with bipolar disorder was developed and translated into 12 languages. The survey was anonymous and completed between March 2014 and January 2016 by 1222 patients in 17 countries. All patients were diagnosed by a psychiatrist. General estimating equations were used to account for correlated data. Results: Overall, 47% of older adults (age 60 years or older) used the Internet versus 87% of younger adults (less than 60 years). More education and having symptoms that interfered with regular activities increased the odds of using the Internet, while being age 60 years or older decreased the odds. Data from 187 older adults and 1021 younger adults were included in the analysis excluding missing values. Conclusions: Older adults with bipolar disorder use the Internet much less frequently than younger adults. Many older adults do not use the Internet, and technology tools are suitable for some but not all older adults. As more health services are only available online, and more digital tools are developed, there is concern about growing health disparities based on age. Mental health experts should participate in determining the appropriate role for digital tools for older adults with bipolar disorder
Experimental evaluation of model predictive current control for a modified three-level four-leg indirect matrix converter
No full textThis study presents an experimental validation and robustness evaluation of predictive current control and reactive power minimisation strategy for a three-level three-phase four-wire indirect matrix converter. The proposed topology features a unification of conventional four-leg indirect matrix converter with an additional four switches circuit resembling a back-to-back buck circuit to synthesise multi-level variable dual dc-link voltage. A systematic rectifier switching strategy is elaborated to ensure positive fictitious dc-link voltage at any instant. The proposed control and topology have been tested under various transient and steady-state conditions for comprehensive robustness evaluation. The experimental results reveal an outstanding independent load current reference tracking with low ripple current and the reactive power minimisation has been achieved by tuning the weighting factor. The load current tracking and reactive power minimisation have been achieved by properly tuning the weighting factor. The load current harmonics distortion is recorded < 5% during normal operating conditions
Enhancement of Thermoelectric Properties of Yb0.25Co4Sb12 Skutterudites through Ni Substitution
No full textIn this work, we investigate the effects of Ni doping on the thermoelectric (TE) properties of Yb0.25Co4Sb12 sample. Yb0.25Co4xNixSb12 (0 ≤ x ≤ 0.5) samples were prepared by mechanical alloying and subsequently consolidated by spark plasma sintering. The morphology of consolidated samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS). The thermoelectric properties of bulk samples were measured from room temperature to 800 K. The XRD analysis confirmed that, the successful formation of the Co4Sb12 skutterudite phase and Ni is substituted into Co site of the skutterudite crystal lattice. Moreover, the electrical resistivity decreased to 14.6 μΩm at 785 K for Yb0.25Co3.5Ni0.5Sb12 sample, due to increase of the electron concentration by Ni-addition. The absolute Seebeck coefficient reached the highest value of 223 μV/K at 592 K for Yb0.25Co3.7Ni0.3Sb12 sample, thus yielding a maximum value of power factor of 2.41 × 10-3 W/mK2 at 592 K. The highest dimensionless thermoelectric figure of merit value ZT of 0.49 at 692 K has been achieved for the Yb0.25Co3.7Ni0.3Sb12 sample, compared to ZT=0.06 for the Yb0.25Co4Sb12 sample at same temperature. This work indicates a strategy to improve the thermoelectric performance by Ni substitution of Co sites in the Yb0.25Co4Sb12 skutterudite through simultaneous improvement of its electrical conductivity, Seebeck coefficient and reduction of its thermal conductivity
In-Filled La0.5Co4Sb12 Skutterudite System with High Thermoelectric Figure of Merit
No full textThe contribution of In addition to the La0.5Co4Sb12 skutterudite structure to improve its thermoelectric properties has been demonstrated. InxLa0.5Co4Sb12 (0 ≤ x ≤ 0.3) samples were prepared through mechanical alloying followed by spark plasma sintering. Characterization of the phase structure and morphology of the sintered InxLa0.5Co4Sb12 bulk samples was carried out using x-ray diffraction (XRD) analysis, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Rietveld analysis of the XRD spectra indicated that double filling at the 2a (000) interstitial site with La and In was successfully achieved, significantly improving the thermoelectric performance of the La0.5Co4Sb12 compound through simultaneous increase in the electrical conductivity and Seebeck coefficient. A maximum power factor of 3.39 × 10−3 W/m-K2 was recorded at 644 K for the In0.3La0.5Co4Sb12 sample, more than 96% of that of the La0.5Co4Sb12 sample. Double filling also effectively reduced the lattice thermal conductivity by about 46%, thus demonstrating that the overall improvement in ZT was primarily due to the reduced thermal conductivity. A maximum ZT value of 1.15 was achieved at 692 K for In0.3La0.5Co4Sb12
Evaluation of disease resistance and tolerance to elevated temperature stress of the selected tissue-cultured Kappaphycus alvarezii Doty 1985 under optimized laboratory conditions
No full textInformation on the abiotic stress tolerance and ice–ice disease resistance properties of tissue-cultured Kappaphycus alvarezii is scarce and can pose a big hurdle to a wider use of tissue-cultured seaweed in the industry. Here, we reported on a study of seaweed-associated bacteria diversity in farmed and tissue-cultured K. alvarezii, and ice–ice disease resistance and elevated growth temperature tolerance of tissue-cultured K. alvarezii in laboratory conditions. A total of 40 endophytic seaweed-associated bacteria strains were isolated from 4 types of K. alvarezii samples based on their colony morphologies, Gram staining properties and 16S rRNA gene sequences. Bacteria strains isolated were found to belong to Alteromonas sp., Aestuariibacter sp., Idiomarina sp., Jejuia sp., Halomonas sp., Primorskyibacter sp., Pseudoalteromonas sp., Ruegeria sp., Terasakiella sp., Thalassospira sp. and Vibrio sp. Vibrio alginolyticus strain ABI-TU15 isolated in this study showed agar-degrading property when analyzed using agar depression assay. Disease resistance assay was performed by infecting healthy K. alvarezii with 105 cells/mL Vibrio sp. ABI-TU15. Severe ice–ice disease symptoms were detected in farmed seaweeds compared to the tissue-cultured K. alvarezii. Besides disease resistance, tissue-cultured K. alvarezii showed better tolerance to the elevated growth temperatures of 30 and 35 °C. In conclusion, our overall data suggests that tissue-cultured K. alvarezii exhibited better growth performance than farmed seaweeds when exposed to elevated growth temperature and ice–ice disease-causing agent
Color analysis of saffron (Crocus sativus L.) as potential natural colorant
No full textPurpose: The purpose of the paper is to study the effect of color stability on introducing chenodeoxycholic acid (CDCA) into a colored liquid extract from saffron and determine the color quality of the extract over a nine-month period. Design/methodology/approach: Six colored liquid samples with different CDCA contents ranging from 0 to 45 Wt.% have been successfully prepared. Chromaticity (C*), color saturation (s), UV-Vis spectroscopy and coloring strength studies have been assessed to determine how CDCA influences the color properties and to study the color quality over time. The color quality was analyzed using the Commission Internationale de l’Eclairage (CIE) system. Findings: All results obtained revealed that the addition of CDCA significantly influenced the overall color performance of the saffron extraction. However, the most pronounced improvement was recorded with the use of 45 Wt.% CDCA. The sample exhibited the highest color quality at the end of nine months of storage with highest absorbance: C* value = 91.38, color saturation = 0.96 and coloring strength = 687. Practical implications: This preliminary study offers significant findings for further research focused on stability of natural colorants extracted from Spanish saffron that can provide benefits for future applications especially in coating industry, food, agriculture, medicine and others. Originality/value: The values of this work can be observed from the information and evidence provided by CIE color stability in terms of chromaticity and saturation, as well as UV-Vis spectrophotometric measurement. It showed that the addition of CDCA additive can help to prolong and enhance the natural colorant properties from Spanish saffron (Crocus sativus L.) for nine month of storage. This proved that by adding additives such as CDCA the saffron colorant can be maintained. To the best of the authors’ concern, this is the first time CDCA is used to prevent color degradation of natural colorant from saffron