Abstract: The application of magnetocardiography signals to detect cardiac electrical function is a new technology developed in recent years. The magnetocardiography signal is detected with Superconducting Quantum Interference Devices (SQUID) and has considerable advantages over electrocardiography (ECG). It is difficult to extract Magnetocardiography (MCG) signal which is buried in the noise, which is a critical issue to be resolved in cardiac monitoring system and MCG applications. In order to remove the severe background noise, the Total Variation (TV) regularization method is proposed to denoise MCG signal. The approach transforms the denoising problem into a minimization optimization problem and the Majorization-minimization algorithm is applied to iteratively solve the minimization problem. However, traditional TV regularization method tends to cause step effect and lacks constraint adaptability. In this paper, an improved TV regularization method for denoising MCG signal is proposed to improve the denoising precision. The improvement of this method is mainly divided into three parts. First, high-order TV is applied to reduce the step effect, and the corresponding second derivative matrix is used to substitute the first order. Then, the positions of the non-zero elements in the second order derivative matrix are determined based on the peak positions that are detected by the detection window. Finally, adaptive constraint parameters are defined to eliminate noises and preserve signal peak characteristics. Theoretical analysis and experimental results show that this algorithm can effectively improve the output signal-to-noise ratio and has superior performance.
Abstract: The efficient usage of the compensation abilities of the electrical drive synchronous motors used in production processes can essentially improve the technical and economic indices of the process. Reducing the flows of the reactive electrical energy due to the compensation of reactive power allows to significantly reduce the load losses of power in the electrical networks. As a result of analyzing the scientific works devoted to the issues of regulating the excitation of the synchronous motors, the need for comprehensive investigation and estimation of the excitation mode has been substantiated. By means of the obtained transmission functions, in the Simulink environment of the software package MATLAB, the transition processes of the excitation mode have been studied. As a result of obtaining and estimating the graph of the Nyquist plot and the transient process, the necessity of developing the Proportional-Integral-Derivative (PID) regulator has been justified. The transient processes of the system of the PID regulator have been investigated, and the amplitude–phase characteristics of the system have been estimated. The analysis of the obtained results has shown that the regulation indices of the developed system have been improved. The developed system can be successfully applied for regulating the excitation voltage of different-power synchronous motors, operating with a changing load, ensuring a value of the power coefficient close to 1.
Abstract: This research attempts to investigate the effects of heteroscedasticity and periodicity in a Panel Data Regression Model (PDRM) by extending previous works on balanced panel data estimation within the context of fitting PDRM for Banks audit fee. The estimation of such model was achieved through the derivation of Joint Lagrange Multiplier (LM) test for homoscedasticity and zero-serial correlation, a conditional LM test for zero serial correlation given heteroscedasticity of varying degrees as well as conditional LM test for homoscedasticity given first order positive serial correlation via a two-way error component model. Monte Carlo simulations were carried out for 81 different variations, of which its design assumed a uniform distribution under a linear heteroscedasticity function. Each of the variation was iterated 1000 times and the assessment of the three estimators considered are based on Variance, Absolute bias (ABIAS), Mean square error (MSE) and the Root Mean Square (RMSE) of parameters estimates. Eighteen different models at different specified conditions were fitted, and the best-fitted model is that of within estimator when heteroscedasticity is severe at either zero or positive serial correlation value. LM test results showed that the tests have good size and power as all the three tests are significant at 5% for the specified linear form of heteroscedasticity function which established the facts that Banks operations are severely heteroscedastic in nature with little or no periodicity effects.
Abstract: Magnetic graphene has received widespread attention for their capability of water and wastewater treatment, which has been attracted many researchers in this field. A bibliometric analysis based on the Web of Science database was employed to analyze the global scientific outputs of magnetic graphene for water treatment until the present time (2012 to 2017), to improve the understanding of the research trends. The publication year, place of publication, institutes, funding agencies, journals, most cited articles, distribution outputs in thematic categories and applications were analyzed. Three major aspects analyzed including type of pollutant, treatment process and composite composition have further contributed to revealing the research trends. The most relevant research aspects of the main technologies using magnetic graphene for water treatment were summarized in this paper. The results showed that research on magnetic graphene for water treatment goes through a period of decline that might be related to a saturated field and a lack of bibliometric studies. Thus, the result of the present work will lead researchers to establish future directions in further studies using magnetic graphene for water treatment.
Abstract: A bibliometric analysis in the Web of Science database was used to identify overall scientific results of graphene inks to date (2008 to 2018). The objective of this study was to evaluate the evolutionary tendency of graphene inks research and to identify its aspects, aiming to provide data that can guide future work. The contributions of different researches, languages, thematic categories, periodicals, place of publication, institutes, funding agencies, articles cited and applications were analyzed. The results revealed a growing number of annual publications, of 258 papers found, 107 were included because they met the inclusion criteria. Three main applications were identified: synthesis and characterization, electronics and surfaces. The most relevant research on graphene inks has been summarized in this article, and graphene inks for electronic devices presented the most incident theme according to the research trends during the studied period. It is estimated that this theme will remain in evidence and will contribute to the direction of future research in this area.
Abstract: This study examines whether corporate governance (CG) mechanisms in firms that have a whistle-blowing policy (WHBLP) are more effective in constraining earnings management (EM), than those without. A sample of 288 Malaysian firms for the years 2013 to 2015, amounting to 864 firm-years were grouped into firms with and without WHBLP. Results show that for firms without WHBLP, the board chairman tenure would minimize EM activities. Meanwhile, for firms with WHBLP, board chairman independence, board chairman tenure, audit committee size, audit committee meeting and women in the audit committees are found to be associated with less EM activities. Further, it is found that ownership concentration and Big 4 auditing firms help to reduce EM activities in firms with WHBLP, while not in firms without WHBLP. Hence, functional and effective governance can be achieved by having a WHBLP, which is in line with agency and resource dependent theories. Therefore, this study suggests that firms should have a WHBLP in place, and policymakers should come up with enhanced criteria to strengthen the mechanisms of WHBLP.
Abstract: Bioactive glasses (BGs) are a group of surface-reactive biomaterials used in clinical applications as implants or filler materials in the human body to repair and replace diseased or damaged bone. Sol-gel technique was employed to prepare a SiO2-CaO-P2O5 glass with nominal composition of 58S BG with the addition of Sr and Li modifiers which imparts special properties to the BG. The effect of simultaneous addition of Sr and Li on bioactivity and biocompatibility, proliferation, alkaline phosphatase (ALP) activity of osteoblast cell line MC3T3-E1 and antibacterial property against methicillin-resistant Staphylococcus aureus (MRSA) bacteria were examined. BGs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy before and after soaking the samples in the simulated body fluid (SBF) for different time intervals to characterize the formation of hydroxyapatite (HA) formed on the surface of BGs. Structural characterization indicated that the simultaneous presence of 5% Sr and 5% Li in 58S-BG composition not only did not retard HA formation because of opposite effect of Sr and Li of the dissolution of BG in the SBF but also, stimulated the differentiation and proliferation of MC3T3-E1s. Moreover, the presence of Sr and Li on dissolution of the ions resulted in an increase in the mean number of DAPI-labeled nuclei which was in good agreement with live/dead assay. The result of antibacterial tests revealed that Sr and Li-substituted 58S BG exhibited a potential antibacterial effect against MRSA bacteria. Because of optimal proliferation and ALP activity of MC3T3-E1cells, proper bioactivity and high antibacterial potential against MRSA, BG-5/5 is suggested as a multifunctional candidate for bone tissue engineering.
Abstract: The major aim of this study was to evaluate the effect of CaO content on in vitro hydroxyapatite formation, MC3T3 cells cytotoxicity and proliferation as well as antibacterial efficiency of sol-gel derived SiO2–CaO–P2O5 ternary system. For this purpose, first two grades of bioactive glass (BG); BG-58s (mol%: 60%SiO2–36%CaO–4%P2O5) and BG-68s (mol%: 70%SiO2–26%CaO–4%P2O5)) were synthesized by sol-gel method. Second, the effect of CaO content in their composition on in vitro bioactivity was investigated by soaking the BG-58s and BG-68s powders in simulated body fluid (SBF) for time periods up to 14 days and followed by characterization inductively coupled plasma atomic emission spectrometry (ICP-AES), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques. Additionally, live/dead staining, 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and alkaline phosphatase (ALP) activity assays were conducted respectively, as qualitatively and quantitatively assess for cell viability, proliferation and differentiations of MC3T3 cells in presence of 58s and 68s BGs. Results showed that BG-58s with higher CaO content showed higher in vitro bioactivity with respect to BG-68s. Moreover, the dissolution rate was inversely proportional to oxygen density of the BG. Live/dead assay revealed that both 58s and 68s increased the mean number live cells which were in good accordance with MTT assay. Furthermore, BG-58s showed more potential antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) bacteria. Taken together, BG-58s with enhanced MC3T3 cells proliferation and ALP activity, acceptable bioactivity and significant high antibacterial effect against MRSA bacteria is suggested as a suitable candidate in order to further functionalizing for delivery of therapeutic ions and growth factors in bone tissue engineering.
Abstract: Yeast cells are generally used as a model system of eukaryotes due to their complex genetic structure, rapid growth ability in optimum conditions, easy replication and well-defined genetic system properties. Thus, yeast cells increased the knowledge of the principal pathways in humans. During fermentation, carbohydrates (hexoses and pentoses) degrade into some toxic by-products such as 5-hydroxymethylfurfural (5-HMF or HMF) and furfural. HMF influences the ethanol yield, and ethanol productivity; it interferes with microbial growth and is considered as a potent inhibitor of bioethanol production. In this study, yeast single cell behavior under HMF application was monitored by using a continuous flow single phase microfluidic platform. Microfluidic device in operation is fabricated by hot embossing and thermo-compression techniques from cyclo-olefin polymer (COP). COP is biocompatible, transparent and rigid material and it is suitable for observing fluorescence of cells considering its low auto-fluorescence characteristic. The response of yeast cells was recorded through Red Fluorescent Protein (RFP) tagged Nop56 gene product, which is an essential evolutionary-conserved nucleolar protein, and also a member of the box C/D snoRNP complexes. With the application of HMF, yeast cell proliferation continued but HMF slowed down the cell growth, and after HMF treatment the cell proliferation stopped. By the addition of fresh nutrient medium, the yeast cells recovered after 6 hours of HMF exposure. Thus, HMF application suppresses normal functioning of cell cycle but it does not cause cells to die. The monitoring of Nop56 expression phases of the individual cells shed light on the protein and ribosome synthesis cycles along with their link to growth. Further computational study revealed that the mechanisms underlying the inhibitory or inductive effects of HMF on growth are enriched in functional categories of protein degradation, protein processing, DNA repair and multidrug resistance. The present microfluidic device can successfully be used for studying the effects of inhibitory agents on growth by single cell tracking, thus capturing cell to cell variations. By metabolic engineering techniques, engineered strains can be developed, and the metabolic network of the microorganism can thus be manipulated such that chemical overproduction of target metabolite is achieved along with the maximum growth/biomass yield.
Abstract: This study aimed to find out chemical and structural suitability of synthesized eppawala hydroxyapatite composite as bone cement, by comparing and contrasting it with human bone as well as commercially available bone cement, which is currently used in orthopedic surgeries. Therefore, a mixture of commercially available bone cement and its liquid monomer, commercially available methyl methacrylate (MMA) and a mixture of solid state synthesized eppawala hydroxyapatite powder with commercially available MMA were prepared as the direct substitution for bone cement. Then physical and chemical properties including composition, crystallinity, presence of functional groups, thermal stability, surface morphology, and microstructural features were examined compared to human bone. Results show that there is a close similarity between synthesized product and human bone and it has exhibited high thermal stability, good crystalline and porous properties than the commercial product. Finally, the study concluded that synthesized hydroxyapatite composite can be used directly as a substitution for commercial bone cement.
Abstract: Goat dairy products are gaining popularity worldwide. In developing countries, but also in many marginal regions of the Mediterranean area, goats represent a great part of the economy and ensure food security. In fact, these small ruminants are able to convert efficiently poor weedy plants and small trees into traditional products of high nutritional quality, showing great resilience to different climatic and environmental conditions. In developed countries, goat milk is appreciated for the presence of health-promoting compounds, bioactive compounds such as conjugated linoleic acids, oligosaccharides, sphingolipids and polyammines. This paper focuses on the recent advances in literature on the nutritional properties of goat milk and on innovative techniques to improve its quality as to become a promising functional food. The environmental sustainability of different methodologies of production has also been examined. Goat milk is valued today as a food of high nutritional value and functional properties as well as small environmental footprint. It is widely consumed in many countries due to high nutritional value, lower allergenic potential, and better digestibility when compared to bovine milk, that makes this product suitable for infants, elderly or sensitive patients. The main differences in chemical composition between a cow and goat milk rely on fat globules that in goat milk are smaller and in fatty acids that present a smaller chain length, while protein, fat, and lactose concentration are comparable. Milk nutritional properties have demonstrated to be strongly influenced by animal diet, genotype, and welfare, but also by season and production systems. Furthermore, there is a growing interest in the dairy industry in goat milk for its relatively high concentration of prebiotics and a good amount of probiotics, which have recently gained importance for their therapeutic potential. Therefore, goat milk is studied as a promising matrix to develop innovative functional foods. In addition to the economic and nutritional value, goat milk is considered a sustainable product for its small environmental footprint, as they require relatively little water and land, and less medical treatments, compared to cow, these characteristics make its production naturally vocated to organic farming. Organic goat milk production has becoming more and more interesting both for farmers and consumers as it can answer to several concerns like environment protection, animal welfare and economical sustainment of rural populations living in marginal lands. These evidences make goat milk an ancient food with novel properties and advantages to be valorized and exploited.
Abstract: In a multilingual setting like Nigeria, the success of service encounters is enhanced by the use of a language that ensures the linguistic and persuasive demands of the interlocutors. This study examined motivations for code switching as a negotiation strategy in bank-hall desk service encounters in Ìbàdàn metropolis using Myers-Scotton’s exploration on markedness in language use. The data consisted of transcribed audio recording of bank-hall service encounters, and direct observation of bank interactions in two purposively sampled commercial banks in Ìbàdàn metropolis. The data was subjected to descriptive linguistic analysis using Myers Scotton’s Markedness Model. Findings reveal that code switching is frequently employed during different stages of service encounter: greeting, transaction and closing to fulfil relational, bargaining and referential functions. Bank staff and customers code switch to make unmarked, marked and explanatory choices. A strategy used to identify with customer’s cultural affiliation, close status gap, and appeal to begrudged customer; or as an explanatory choice with non-literate customers for ease of communication. Bankers select English to maintain customers’ perceptions of prestige which is retained or diverged from depending on their linguistic preference or ability. Yoruba is seen as an efficient negotiation strategy with both bankers and their customers, making choices within conversation to achieve desired conversational and functional aims.
Abstract: Simulation modeling can be used to solve real world problems. It provides an understanding of a complex system. To develop a simplified model of process simulation, a suitable experimental design is required to be able to capture surface characteristics. This paper presents the experimental design and algorithm used to model the process simulation for optimization problem. The CO2 liquefaction based on external refrigeration with two refrigeration circuits was used as a simulation case study. Latin Hypercube Sampling (LHS) was purposed to combine with existing Central Composite Design (CCD) samples to improve the performance of CCD in generating the second order model of the system. The second order model was then used as the objective function of the optimization problem. The results showed that adding LHS samples to CCD samples can help capture surface curvature characteristics. Suitable number of LHS sample points should be considered in order to get an accurate nonlinear model with minimum number of simulation experiments.
Abstract: Attention-Deficit/Hyperactivity Disorder (ADHD), epilepsy, and autism affect millions of children worldwide, many of which are undiagnosed despite the fact that all of these disorders are detectable in early childhood. Late diagnosis can cause severe problems due to the late treatment and to the misconceptions and lack of awareness as a whole towards these disorders. Moreover, electroencephalography (EEG) has played a vital role in the assessment of neural function in children. Therefore, quantitative EEG measurement will be utilized as a tool for use in the evaluation of patients who may have ADHD, epilepsy, and autism. We propose a screening tool that uses EEG signals and machine learning algorithms to detect these disorders at an early age in an automated manner. The proposed classifiers used with epilepsy as a step taken for the work done so far, provided an accuracy of approximately 97% using SVM, Naïve Bayes and Decision tree, while 98% using KNN, which gives hope for the work yet to be conducted.
Abstract: In many Iranian cities including Mashhad, the capital of Razavi Khorasan Province, ordinary samples of domestic architecture on a small scale is not considered as heritage. While the principals of house formation are respected in all traditional Iranian houses; from moderate to great ones. During the past decade, Mashhad has lost its identity, and has become a modern city. Identifying it as the capital of the Islamic Culture in 2017 by ISESCO and consequently looking for new developments and transfiguration caused to demolish a large number of traditional modest habitation. For this reason, the present paper aims to introduce the three undiscovered houses with the historical and monumental values located in the oldest neighborhoods of Mashhad which have been neglected in the cultural heritage field. The preliminary phase of this approach will be a measured survey to identify the significant characteristics of selected dwellings and understand the challenges through focusing on building form, orientation, room function, space proportion and ornamental elements’ details. A comparison between the case studies and the wealthy domestically buildings presents that a house belongs to inhabitants with an average income could introduce the same accurate, regular, harmonic and proportionate design which can be found in the great mansions. It reveals that an ordinary traditional house can be regarded as valuable construction not only for its historical characteristics but also for its aesthetical and architectural features that could avoid further destructions in the future.
Abstract: The supply of potable water at least is a very important index in national development. Water tariffs depend on the treatment cost which carries the highest percentage of the total operation cost in any water supply scheme. In order to keep water tariffs as low as possible, treatment costs have to be minimized. The University of Ibadan, Nigeria, water supply scheme consists of a treatment plant with three distribution stations (Amina way, Kurumi and Lander) and two raw water supply sources (Awba dam and Eleyele dam). An operational study of the scheme was carried out to ascertain the efficiency of the supply of potable water on the campus to justify the need for water supply schemes in tertiary institutions. The study involved regular collection, processing and analysis of periodic operational data. Data collected include supply reading (water production on daily basis) and consumers metered reading for a period of 22 months (October 2013 - July 2015), and also collected, were the operating hours of both plants and human beings. Applying the required mathematical equations, total loss was determined for the distribution system, which was translated into monetary terms. Adequacies of the operational functions were also determined. The study revealed that water supply scheme is justified in tertiary institutions. It was also found that approximately 10.7 million Nigerian naira (N) is lost to leakages during the 22-month study period; the system’s storage capacity is no longer adequate, especially for peak water production. The capacity of the system as a whole is insufficient for the present university population and that the existing water supply system is not being operated in an optimal manner especially due to personnel, power and system ageing constraints.
Abstract: The capacity of conventional cellular networks has
reached its upper bound and it can be well handled by introducing
femtocells with low-cost and easy-to-deploy. Spectrum interference
issue becomes more critical in peace with the value-added multimedia
services growing up increasingly in two-tier cellular networks.
Spectrum allocation is one of effective methods in interference
mitigation technology. This paper proposes a game-theory-based on
OFDMA downlink spectrum allocation aiming at reducing co-channel
interference in two-tier femtocell networks. The framework is
formulated as a non-cooperative game, wherein the femto base
stations are players and frequency channels available are strategies.
The scheme takes full account of competitive behavior and
fairness among stations. In addition, the utility function reflects
the interference from the standpoint of channels essentially. This
work focuses on co-channel interference and puts forward a negative
logarithm interference function on distance weight ratio aiming
at suppressing co-channel interference in the same layer network.
This scenario is more suitable for actual network deployment and
the system possesses high robustness. According to the proposed
mechanism, interference exists only when players employ the same
channel for data communication. This paper focuses on implementing
spectrum allocation in a distributed fashion. Numerical results show
that signal to interference and noise ratio can be obviously improved
through the spectrum allocation scheme and the users quality of
service in downlink can be satisfied. Besides, the average spectrum
efficiency in cellular network can be significantly promoted as
simulations results shown.
Abstract: The separation of speech signals has become a research
hotspot in the field of signal processing in recent years. It has
many applications and influences in teleconferencing, hearing aids,
speech recognition of machines and so on. The sounds received are
usually noisy. The issue of identifying the sounds of interest and
obtaining clear sounds in such an environment becomes a problem
worth exploring, that is, the problem of blind source separation.
This paper focuses on the under-determined blind source separation
(UBSS). Sparse component analysis is generally used for the problem
of under-determined blind source separation. The method is mainly
divided into two parts. Firstly, the clustering algorithm is used to
estimate the mixing matrix according to the observed signals. Then
the signal is separated based on the known mixing matrix. In this
paper, the problem of mixing matrix estimation is studied. This paper
proposes an improved algorithm to estimate the mixing matrix for
speech signals in the UBSS model. The traditional potential algorithm
is not accurate for the mixing matrix estimation, especially for low
signal-to noise ratio (SNR).In response to this problem, this paper
considers the idea of an improved potential function method to
estimate the mixing matrix. The algorithm not only avoids the inuence
of insufficient prior information in traditional clustering algorithm,
but also improves the estimation accuracy of mixing matrix. This
paper takes the mixing of four speech signals into two channels as
an example. The results of simulations show that the approach in this
paper not only improves the accuracy of estimation, but also applies
to any mixing matrix.
Abstract: This study had two main aims: firstly, to determine how the individual substitution of CaO/MgO and CaO/SrO can affect the in vitro bioactivity of sol-gel derived substituted 58S bioactive glass (BG) and secondly to introduce a composition in the 60SiO2–(36-x)CaO–4P2O5–(x)MgO and 60SiO2–(36-x)CaO–4P2O5–(x)SrO quaternary systems (where x= 0, 5, 10 mol.%) with enhanced biocompatibility, alkaline phosphatase (ALP) activity, and more efficient antibacterial activity against MRSA bacteria. Results showed that both magnesium-substituted bioactive glasses (M-BGs) and strontium- substituted bioactive glasses (S-BGs) retarded the Hydroxyapatite (HA) formation. Meanwhile, magnesium had more pronounced effect. The 3-(4, 5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and ALP assays revealed that the presence of moderate amount (5 mol%) of Mg and Sr had a stimulating effect on increasing of both proliferation and differentiation of MC3T3-E1 cells. Live dead and Dapi/actin staining revealed both substitution of CaO/MgO and CaO/SrO resulted in more biocompatibility and stimulation potential of the MC3T3 cells compared with control. Taken together, among all of the synthesized magnesium substituted (MBGs) and strontium substituted (SBGs), the sample 58- BG with 5 mol% CaO/MgO substitution (BG-5M) was considered as a multifunctional biomaterial in bone tissue regeneration field with enhanced biocompatibility, ALP activity as well as the highest antibacterial efficiency against methicillin-resistant Staphylococcus aureus (MRSA) bacteria.
Abstract: Audit is an independent inspection of the financial statement of the audited person and expresses the opinion of an auditor on the reliability of this statement. The auditor’s activity (auditor’s service) is realized by auditing organizations, individual auditors in connection to conduction of an audit and rendering of audit accompanying services. The profession of auditor means a high level of responsibility for rendered service. Results of decisions made by information users depend on the quality of the auditor’s conclusion. Owners, investors, creditors, and society rely on the opinion of the auditor under the condition that inspection was conducted with good quality. Therefore, the existence of the well-functioning audit quality control system for the administering of the audit is an important issue. An efficient audit quality control system is a substantial challenge that many countries face worldwide, especially those states where these systems are being formed within the respective reform program. The presented article reflects on the best practices of the leading countries, the assumptions and recommendations for the financial accounting, reporting and audit; current reforms in Georgia are made based on this comparative analysis.