19672 research outputs found
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Skeletonema costatum of mangrove ecosystem: Its dynamics across physico-chemical parameters variability
No full textAs part of a monitoring programme, twelve months total phytoplankton sampling were carried out starting from April 2009 to March 2010 in Carey Island mangrove ecosystem across measured physico-chemical and total phytoplankton diversity parameters. Across the one year sampling period, we found three major occurrences of mono-species bloom of Skeletonema costatum in the month of April, May and August 2009, in which the water body at study site displayed dark brown colour. This diatom species that displayed significant temporal variation has been found to grow rapidly when the nitrate concentration and temperature of the water column were > 0.6 mg L -1 and > 31°C, respectively. This study shows that S. costatum displayed negative correlation with dissolved oxygen in the water column. Increase in S. costatum cells abundance at the study site proved to destabilize total phytoplankton diversity by decreasing the equitability (measured by evenness) of total phytoplankton. © 2019, BIOFLUX SRL. All rights reserved
Epilepsy research output in Southeast Asian countries: A systematic review
No full textObjective: Epilepsy is understudied in Southeast Asian (SEA) countries. This systematic review aimed to determine the number of epilepsy publications performed in SEA and identify factors associated with research output in this region. Methods: Existing academic journal article searches were performed using PubMed, Scopus, Medline and Web of Science till 1st March 2018. Openness is determined by the use of English in medical school and overseas epilepsy fellowship. Results: A total of 702 epilepsy articles have been published in the last 50 years in the SEA region, with an exponential increase of publications after the year 1997, with the cumulative number doubled every 5 years. Only half (54%) were published in the journals with impact factor (IF) ≥1. Majority of the publications (48.2%) employed cross sectional design, followed by animal or laboratory studies (21.1%), with few randomized controlled trials and systematic review/meta-analysis studies (1.7% and 2.3%, respectively). Half (52.9%) of the publications were clinical studies. The number of papers with IF≥1 correlated positively with openness to international standard (R=0.720, p<0.05), and knowledge-based economy (p=0.01). Conclusion: Epilepsy research output in SEA is low in quantity and quality. The output is mainly related to the type of economy (knowledge-based or non-knowledge-based) and openness to international ideas and standard. © 2019, ASEAN Neurological Association. All rights reserved
A Quasi-periodic Propagating Wave and Extreme-ultraviolet Waves Excited Simultaneously in a Solar Eruption Event
No full textQuasi-periodic fast-propagating (QFP) magnetosonic waves and extreme-ultraviolet (EUV) waves were proposed to be driven by solar flares and coronal mass ejections (CMEs), respectively. In this Letter, we present a detailed analysis of an interesting event in which we find that both QFP magnetosonic waves and EUV waves are excited simultaneously in one solar eruption event. The co-existence of the two wave phenomena offers an excellent opportunity to explore their driving mechanisms. The QFP waves propagate in a funnel-like loop system with a speed of 682-837 km s -1 and a lifetime of 2 minutes. On the contrary, the EUV waves, which present a faster component and a slower component, propagate in a wide angular extent, experiencing reflection and refraction across a magnetic quasi-separatrix layer. The faster component of the EUV waves travels with a speed of 412-1287 km s -1 , whereas the slower component travels with a speed of 246-390 km s -1 . The lifetime of the EUV waves is ∼15 minutes. It is revealed that the faster component of the EUV waves is cospatial with the first wavefront of the QFP wave train. The QFP waves have a period of about 45±5 s, which is absent in the associated flares. All of these results imply that QFP waves can also be excited by mass ejections, including CMEs or jets. © 2019. The American Astronomical Society. All rights reserved
Clasp-Knife Model of Muscle Spasticity for Simulation of Robot-Human Interaction
No full textThe objective of this research was to replicate the muscle tone moment feedback of elbow upon passive mobilization and classify them based on modified ashworth scale criterion using a mathematical model. The proposed model enables the visualization of muscle tone pattern for robotic interaction simulation. A concurrent muscle tone model necessitates a jerk effect to fully replicate the catch and release effect, also known as, clasp-knife phenomenon of muscle tone feedback. However, the research of passive mobilization control interaction between robot and subject does not emulate such phenomenon. Thus, the model was improvised to replicate the clasp-knife phenomenon according to the robot's gross kinematics and dynamics. The model was designed based on the quantitative pattern of muscle tone feedback from subject with spasticity. The simulated model was then correlated to clinical measures using similar kinematic and dynamic input. The velocity dynamic input was splined to obtain the velocity trend without the jerk effect. The results obtained from the proposed model were relatively promising with an overall (n=9× 4) linear (Pearson) correlated average of -r=0.8348 for nine subjects with correlation significant at the 0.01 level (p< 0.01) and five of them presented a distinctive clasp-knife phenomenon with correlation average of -r=0.8631. © 2018 IEEE
New evidence on fund performance in extreme events
No full textPurpose: The purpose of this paper is to compare the return performance and persistence of ethical and conventional mutual funds during two extreme events, the Asian and the global financial crises under Shariah constraints. Design/methodology/approach: The overall sample comprises of 129 Islamic mutual funds (IMFs) and 350 conventional mutual funds (CMFs) in Malaysia, and the average monthly data cover two periods of market cycles, before and during a financial crisis. The net of all expenses data is obtained from the Morningstar Database. This study employs various market risk-adjusted performance measures (ratios) to estimate the funds’ overall performance during the crises, and then it uses CAPM model to estimate the parameters via panel data approach. Moreover, paper employs the two persistence performance measures on IMFs and CMFs through contingency tables. It tests for the performance persistence effects for IMFs, CMFs using repeat winner and the cross-product ratio (CPR) tests proposed by Malkiel (1995) and Brown and Goetzmann (1995), respectively. Findings: The main findings of the paper are: on average, both funds IMF and the CMF outperform the market return during the entire sample period; none of the funds is better than the “others” during the financial crises and the pre-crisis periods; the ethical fund – IMF outperforms the CMF over the study period. This outcome also indicates that ethical funds are more persistent especially during and the pre-crisis AFC and the GFC periods. Research limitations/implications: The finding of this study is limited to only Malaysian data because the objective was to guideline investors and market players in Malaysia to prefer investing in Islamic ethical funds to diversify their investment portfolio. Practical implications: Cautions to use existing ratio measures and CAPM model rather persistence measures may be used with existing methodologies in light of extreme events which influenced investor decision making for better returns at lower risks. Social implications: A class of ethical funds consists of religious sustainable, socially responsible and impact-investing (SRI) funds but Shariah implications of halal investment must be observed to avoid prohibited practices within the class of SRI funds. Originality/value: The work done in this paper are original in the sense that the authors employed various ratios to measure fund performance in conjunction with CAPM model and then tested for two persistence performance measures; the repeat winner and CPR tests. © 2019, Emerald Publishing Limited
Propitious Escalation in Photocurrent Response from MnZnO3 Thin Films Using Methanol as Sacrificial Agent
No full textAbstract: The thin film of MnZnO3 was prepared from Mn-Zn complex [Mn2Zn2(TFA)8(THF)4]n(1) (where TFA = trifluroactetato and THF = tetrahydrofuran) via aerosol-assisted chemical vapour deposition. The stoichiometry and oxidation of individual elements of the films were determined by x-ray photoelectron spectroscopy. The field emission gun-scanning electron microscopic images confirmed that the film deposited at 500°C show an agglomerated flower-like structure. The photoelectrocatalytic performance of as-deposited MnZnO3 was evaluated for methanol oxidation using 1Sun illumination (100 mW cm−2). The MnZnO3 photoelectrode showed a photocurrent density of 2.5 mA cm−2 in the presence of 0.6 M methanol, which is three times of that in the absence of methanol. Furthermore, the chronoamperometric results revealed that the films are highly stable and resistive towards photo-corrosion under alkaline media. Impedance studies further elucidated the addition of minute quantity of methanol accelerates the charge transfer by its rapid photoxidation. Graphical Abstract: [Figure not available: see fulltext.] © 2019, The Minerals, Metals & Materials Society
Resistance element weld-bonding and resistance spot weld-bonding of Mg alloy/austenitic stainless steel
No full textMg alloy/austenitic stainless steel (ASS) joints were produced by resistance element weld-bonding (REWB) and resistance spot weld-bonding (RSWB) techniques. Both joints consisted of two zones, namely, the adhesive zone and weld zone. The weld zone of the REWB joints was formed through a metallurgical reaction between the rivet and ASS. The microstructure of the fusion zone consisted of austenite and intercrystalline delta ferrite. The weld zone of the RSWB joints was formed via welding-brazing mechanism (involving molten Mg alloy and solid ASS), and the nugget was formed in the Mg alloy. The nugget microstructure consisted of fine columnar dendritic structure. Digital image correlation (DIC) analysis was used to study the deformation behavior and strain evolution in the loading direction during lap-shear test. The REWB and RSWB joints experienced lower degree of out-of-plane displacement, sustained higher peak load, and exhibited higher strain to failure than their conventional counterparts. However, the REWB joints exhibited superior lap-shear performance, with high energy absorption and favorable failure mode (pull out failure in the ASS sheet). Upon the failure of the adhesive zone at peak load, the load was sustained by the weld, and the final failure occurred via pullout mode in the ASS. The RSWB joints failed in a sudden manner, mainly by cohesive failure in the adhesive zone and Mg alloy nugget/ASS interface failure in the weld zone. © 2019 The Society of Manufacturing Engineer
Passively Q-switched erbium-doped fiber laser using quantum dots CdSe embedded in polymer film as saturable absorber
No full textWe demonstrate a passively Q-switched erbium doped fiber laser (EDFL) based on quantum dots (QD) CdSe as a saturable absorber (SA). The synthesized CdSe powder was embedded into a poly(methyl methacrylate) (PMMA) using emulsion polymerization process. The film is sandwiched between two fiber connector via an adapter to form a fiber-compatible SA device. By integrating the SA device into the EDFL ring cavity, the stable Q-switched operation is achieved at 1559.35 nm as the pump power is varied within 30–118 mW. The laser has a pump threshold of 20.4 mW. The pulse repetition rate shows an increasing trend from 33.2 to 68.45 kHz, whereas the pulse width exhibits a decreasing trend from 10.04 to 4.30 μs as the pump power is increased from 30 to 118 mW. The highest pulse energy of 11.83 nJ is obtained at a pump power of 118 mW. These results indicate that QD CdSe is a promising SA for Q-switching laser operation. © 2019, Springer Science+Business Media, LLC, part of Springer Nature
Investigation of fusion features for apple classification in smart manufacturing
No full textSmart manufacturing optimizes productivity with the integration of computer control and various high level adaptability technologies including the big data evolution. The evolution of big data offers optimization through data analytics as a predictive solution in future planning decision making. However, this requires accurate and reliable informative data as input for analytics. Therefore, in this paper, the fusion features for apple classification is investigated to classify between defective and non-defective apple for automatic inspection, sorting and further predictive analytics. The fusion features with Decision Tree classifier called CurveletWavelet-Gray Level Co-occurrence Matrix (CW-GLCM) is designed based on symmetrical pattern. The CW-GLCM is tested on two apple datasets namely NDDA and NDDAWwith a total of 1110 apple images. Each dataset consists of a binary class of apple which are defective and non-defective. The NDDAW consists more low-quality region images. Experimental results show that CW-GLCM successfully classify 98.15% of NDDA dataset and 89.11% of NDDAW dataset. A lower classification accuracy is observed in other five existing image recognition methods especially on NDDAW dataset. Finally, the results show that CW-GLCM is more accurate among all the methods with the difference of more than 10.54% of classification accuracy. © 2019 by the authors
Effects of lipid packing and intermolecular hydrogen bond on thermotropic phase transition of stearyl glucoside
No full textThe sugar anomeric effect on the thermotropic phase transition of stearyl glucoside was investigated. Standard analysis to study the phase transition through differential scanning calorimetry (DSC), and optical polarizing microscopy (OPM) was applied. In addition, small- and wide-angle X-ray scattering (SWAXS) and impedance spectroscopy (IS) were used to elucidate the phase structural information and the dielectric response of the glycolipid self-assembly system, respectively. A distinctive solid-to-liquid crystal phase transition of α- and β-stearyl glucoside was observed. At ambient temperature we observed semi-crystalline structure for the former and gel phase for the latter. α-Stearyl glucoside showed only one-step transition from semi-crystal to lamellar liquid crystal phase. In contrast, the gel phase of β-stearyl glucoside showed several distinct transition states prior to lamellar liquid crystal phase. Here the underlying reason for the observed β-stearyl glucoside polymorphism possibly involved strong intermolecular interaction originating from the combination of interlayer H-bonding and intralayer van der Waals forces. © 2019 Elsevier B.V