Search results for: functional random differential equation

Authors: Michail Milas, Aikaterini Dafni Tegiou, Nickolas Rigopoulos, Eustathios Giaouris, Zaharias Loannou

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Nanotechnology, a relatively new scientific field, addresses the manipulation of nanoscale materials and devices, which are governed by unique properties, and is applied in a wide range of industries, including food packaging. The incorporation of nanoparticles into polymer matrices used for food packaging is a field that is highly researched today. One such combination is silver nanoparticles with polypropylene. In the present study, the synthesis of the silver nanoparticles was carried out by a natural method. In particular, a ripe banana peel extract was used. This method is superior to others as it stands out for its environmental friendliness, high efficiency and low-cost requirement. In particular, a 1.75 mM AgNO₃ silver nitrate solution was used, as well as a BPE concentration of 1.7% v/v, an incubation period of 48 hours at 70°C and a pH of 4.3 and after its preparation, the polypropylene films were soaked in it. For the PP films, random PP spheres were melted at 170-190°C into molds with 0.8cm diameter. This polymer was chosen as it is suitable for plastic parts and reusable plastic containers of various types that are intended to come into contact with food without compromising its quality and safety. The antimicrobial test against Escherichia coli DFSNB1 and Staphylococcus epidermidis DFSNB4 was performed on the films. It appeared that the films with silver nanoparticles had a reduction, at least 100 times, compared to those without silver nanoparticles, in both strains. The limit of detection is the lower limit of the vertical error lines in the presence of nanoparticles, which is 3.11. The main reasons that led to the adsorption of nanoparticles are the porous nature of polypropylene and the adsorption capacity of nanoparticles on the surface of the films due to hydrophobic-hydrophilic forces. The most significant parameters that contributed to the results of the experiment include the following: the stage of ripening of the banana during the preparation of the plant extract, the temperature and residence time of the nanoparticle solution in the oven, the residence time of the polypropylene films in the nanoparticle solution, the number of nanoparticles inoculated on the films and, finally, the time these stayed in the refrigerator so that they could dry and be ready for antimicrobial treatment.

Keywords: antimicrobial control, banana peel extract, E. coli, natural synthesis, microbe, plant extract, polypropylene films, S.epidermidis, silver nano, random pp

Procedia PDF Downloads 172

Authors: Tabassum Riaz

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This study provides a complete examination of the stock prices behavior in the Karachi stock exchange. It examines that whether Karachi stock exchange can be described as mean reversion or not. For this purpose daily, weekly and monthly index data from Karachi stock exchange ranging from period July 1, 1997 to July 2, 2011 was taken. After employing the Multiple variance ratio and unit root tests it is concluded that stock market follow mean reversion behavior and hence have reverting trend which opens the door for the active invest management. Thus technical analysis may be help to identify the potential areas for value creation.

Keywords: mean reversion, random walk, technical analysis, Karachi stock exchange

Procedia PDF Downloads 422

Authors: Young Ik Suh, Tywan G. Martin

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Bundling strategy is a common marketing practice today. In the past decades, both academicians and practitioners have increasingly emphasized the strategic importance of bundling in today’s markets. The reason for increased interest in bundling strategy is that they normally believe that it can significantly increase profits on organization’s sales over time and it is convenient for the customer. However, little efforts has been made on ticket bundling and purchase considerations in hedonic and utilitarian options in sport consumer behavior context. Consumers often face choices between utilitarian and hedonic alternatives in decision making. When consumers purchase certain products, they are only interested in the functional dimensions, which are called utilitarian dimensions. On the other hand, others focus more on hedonic features such as fun, excitement, and pleasure. Thus, the current research examines how utilitarian and hedonic consumption can vary in typical ticket purchasing process. The purpose of this research is to understand the following two research themes: (1) the differential effect of discount framing on ticket bundling: utilitarian and hedonic options and (2) moderating effect of team identification on ticket bundling. In order to test the research hypotheses, an experimental study using a two-way ANOVA, 3 (team identification: low, medium, and high) X 2 (discount frame: ticket bundle sales with utilitarian product, and hedonic product), with mixed factorial design will be conducted to determine whether there is a statistical significance between purchasing intentions of two discount frames of ticket bundle sales within different team identification levels. To compare mean differences among the two different settings, we will create two conditions of ticket bundles: (1) offering a discount on a ticket ($5 off) if they would purchase it along with utilitarian product (e.g., iPhone8 case, t-shirt, cap), and (2) offering a discount on a ticket ($5 off) if they would purchase it along with hedonic product (e.g., pizza, drink, fans featured on big screen). The findings of the current ticket bundling study are expected to have many theoretical and practical contributions and implications by extending the research and literature pertaining to the relationship between team identification and sport consumer behavior. Specifically, this study can provide a reliable and valid framework to understanding the role of team identification as a moderator on behavioral intentions such as purchase intentions. From an academic perspective, the study will be the first known attempt to understand consumer reactions toward different discount frames related to ticket bundling. Even though the game ticket itself is the major commodity of sport event attendance and significantly related to teams’ revenue streams, most recent ticket pricing research has been done in terms of economic or cost-oriented pricing and not from a consumer psychological perspective. For sport practitioners, this study will also provide significant implications. The result will imply that sport marketers may need to develop two different ticketing promotions for loyal fan and non-loyal fans. Since loyal fans concern ticket price than tie-in products when they see ticket bundle sales, advertising campaign should be more focused on discounting ticket price.

Keywords: ticket bundling, hedonic, utilitarian, team identification

Procedia PDF Downloads 162

Authors: Chahid K. Ghaddar

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The spreadsheet engine is exploited via a non-conventional mechanism to enable novel worksheet solver functions for computational calculus. The solver functions bypass inherent restrictions on built-in math and user defined functions by taking variable formulas as a new type of argument while retaining purity and recursion properties. The enabling mechanism permits integration of numerical algorithms into worksheet functions for solving virtually any computational problem that can be modelled by formulas and variables. Several examples are presented for computing integrals, derivatives, and systems of deferential-algebraic equations. Incorporation of the worksheet solver functions with the ubiquitous spreadsheet extend the utility of the latter as a powerful tool for computational mathematics.

Keywords: calculus, differential algebraic equations, solvers, spreadsheet

Procedia PDF Downloads 354

Authors: Ting Lu, Ya-Ru Diao, Fei Fan, Ye Xue, Lei Shi, Xian-e Tang, Meng-jun Zhan, Zhen-hua Deng

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Accurate adult age estimation (AAE) is a significant and challenging task in forensic and archeology fields. Attempts have been made to explore optimal adult age metrics, and the rib is considered a potential age marker. The traditional way is to extract age-related features designed by experts from macroscopic or radiological images followed by classification or regression analysis. Those results still have not met the high-level requirements for practice, and the limitation of using feature design and manual extraction methods is loss of information since the features are likely not designed explicitly for extracting information relevant to age. Deep learning (DL) has recently garnered much interest in imaging learning and computer vision. It enables learning features that are important without a prior bias or hypothesis and could be supportive of AAE. This study aimed to develop DL models for AAE based on CT images and compare their performance to the manual visual scoring method. Chest CT data were reconstructed using volume rendering (VR). Retrospective data of 2500 patients aged 20.00-69.99 years were obtained between December 2019 and September 2021. Five-fold cross-validation was performed, and datasets were randomly split into training and validation sets in a 4:1 ratio for each fold. Before feeding the inputs into networks, all images were augmented with random rotation and vertical flip, normalized, and resized to 224×224 pixels. ResNeXt was chosen as the DL baseline due to its advantages of higher efficiency and accuracy in image classification. Mean absolute error (MAE) was the primary parameter. Independent data from 100 patients acquired between March and April 2022 were used as a test set. The manual method completely followed the prior study, which reported the lowest MAEs (5.31 in males and 6.72 in females) among similar studies. CT data and VR images were used. The radiation density of the first costal cartilage was recorded using CT data on the workstation. The osseous and calcified projections of the 1 to 7 costal cartilages were scored based on VR images using an eight-stage staging technique. According to the results of the prior study, the optimal models were the decision tree regression model in males and the stepwise multiple linear regression equation in females. Predicted ages of the test set were calculated separately using different models by sex. A total of 2600 patients (training and validation sets, mean age=45.19 years±14.20 [SD]; test set, mean age=46.57±9.66) were evaluated in this study. Of ResNeXt model training, MAEs were obtained with 3.95 in males and 3.65 in females. Based on the test set, DL achieved MAEs of 4.05 in males and 4.54 in females, which were far better than the MAEs of 8.90 and 6.42 respectively, for the manual method. Those results showed that the DL of the ResNeXt model outperformed the manual method in AAE based on CT reconstruction of the costal cartilage and the developed system may be a supportive tool for AAE.

Keywords: forensic anthropology, age determination by the skeleton, costal cartilage, CT, deep learning

Procedia PDF Downloads 67

Authors: Ivan Potapov

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Background: The aim of this paper is to investigate poly code texts in the communication of youth antisocial groups. Nowadays, the notion of a text has numerous interpretations. Besides all the approaches to defining a text, we must take into account semiotic and cultural-semiotic ones. Rapidly developing IT, world globalization, and new ways of coding of information increase the role of the cultural-semiotic approach. However, the development of computer technologies leads also to changes in the text itself. Polycode texts play a more and more important role in the everyday communication of the younger generation. Therefore, the research of functional and pragmatic aspects of both verbal and non-verbal content is actually quite important. Methods and Material: For this survey, we applied the combination of four methods of text investigation: not only intention and content analysis but also semantic and syntactic analysis. Using these methods provided us with information on general text properties, the content of transmitted messages, and each communicants’ intentions. Besides, during our research, we figured out the social background; therefore, we could distinguish intertextual connections between certain types of polycode texts. As the sources of the research material, we used 20 public channels in the popular messenger Telegram and data extracted from smartphones, which belonged to arrested members of antisocial groups. Findings: This investigation let us assert that polycode texts can be characterized as highly intertextual language unit. Moreover, we could outline the classification of these texts based on communicants’ intentions. The most common types of antisocial polycode texts are a call to illegal actions and agitation. What is more, each type has its own semantic core: it depends on the sphere of communication. However, syntactic structure is universal for most of the polycode texts. Conclusion: Polycode texts play important role in online communication. The results of this investigation demonstrate that in some social groups using these texts has a destructive influence on the younger generation and obviously needs further researches.

Keywords: text, polycode text, internet linguistics, text analysis, context, semiotics, sociolinguistics

Procedia PDF Downloads 129

Authors: Kwangin Kim, Taewon Yoo, Haksoo Han

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Polyimide is a superior polymer in the electronics industry, and we conducted a study to synthesize poly(amide-imide) at low temperatures. Poly(amide-imide) was synthesized at low-temperature curing to offer a thermal stable membrane with low residual stress and good processability. As a result, the low crack polymer with good processability could be used to various applications such as semiconductors, integrated circuits, coating materials, membranes, and display. The synthesis of poly(amide-imide) at low temperatures was confirmed by Fourier transform infrared spectroscopy (FT-IR). Thermal stabilities of the polymer was confirmed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).

Keywords: poly(amide-imide), residual stress, thermal stability

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Authors: Sugandha Gupta, Arun Kumar Jha

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A large number of ferroelectric materials have been intensely investigated for applications in non-volatile ferroelectric random access memories (FeRAMs), piezoelectric transducers, actuators, pyroelectric sensors, high dielectric constant capacitors, etc. Bismuth layered ferroelectric materials such as Strontium Bismuth Tantalate (SBT) has attracted a lot of attention due to low leakage current, high remnant polarization and high fatigue endurance up to 1012 switching cycles. However, pure SBT suffers from various major limitations such as high dielectric loss, low remnant polarization values, high processing temperature, bismuth volatilization, etc. Significant efforts have been made to improve the dielectric and ferroelectric properties of this compound. Firstly, it has been reported that electrical properties vary with the Sr/ Bi content ratio in the SrBi2Ta2O9 compsition i.e. non-stoichiometric compositions with Sr-deficient / Bi excess content have higher remnant polarization values than stoichiometic SBT compositions. With the objective to improve structural, dielectric, ferroelectric and piezoelectric properties of SBT compound, rare earth holmium (Ho3+) was chosen as a donor cation for substitution onto the Bi2O2 layer. Moreover, hardly any report on holmium substitution in stoichiometric SrBi2Ta2O9 and non-stoichiometric Sr0.8Bi2.2Ta2O9 compositions were available in the literature. The holmium substituted SrBi2-xHoxTa2O9 (x= 0.00-2.0) and Sr0.8Bi2.2Ta2O9 (x=0.0 and 0.01) compositions were synthesized by the solid state reaction method. The synthesized specimens were characterized for their structural and electrical properties. X-ray diffractograms reveal single phase layered perovskite structure formation for holmium content in stoichiometric SBT samples up to x ≤ 0.1. The granular morphology of the samples was investigated using scanning electron microscope (Hitachi, S-3700 N). The dielectric measurements were carried out using a precision LCR meter (Agilent 4284A) operating at oscillation amplitude of 1V. The variation of dielectric constant with temperature shows that the Curie temperature (Tc) decreases on increasing the holmium content. The specimen with x=2.0 i.e. the bismuth free specimen, has very low dielectric constant and does not show any appreciable variation with temperature. The dielectric loss reduces significantly with holmium substitution. The polarization–electric field (P–E) hysteresis loops were recorded using a P–E loop tracer based on Sawyer–Tower circuit. It is observed that the ferroelectric property improve with Ho substitution. Holmium substituted specimen exhibits enhanced value of remnant polarization (Pr= 9.22 μC/cm²) as compared to holmium free specimen (Pr= 2.55 μC/cm²). Piezoelectric co-efficient (d33 values) was measured using a piezo meter system (Piezo Test PM300). It is observed that holmium substitution enhances piezoelectric coefficient. Further, the optimized holmium content (x=0.01) in stoichiometric SrBi2-xHoxTa2O9 composition has been substituted in non-stoichiometric Sr0.8Bi2.2Ta2O9 composition to obtain further enhanced structural and electrical characteristics. It is expected that a new class of ferroelectric materials i.e. Rare Earth Layered Structured Ferroelectrics (RLSF) derived from Bismuth Layered Structured Ferroelectrics (BLSF) will generate which can be used to replace static (SRAM) and dynamic (DRAM) random access memories with ferroelectric random access memories (FeRAMS).

Keywords: dielectrics, ferroelectrics, piezoelectrics, strontium bismuth tantalate

Procedia PDF Downloads 204

Authors: Camila Lee Park, Mauro Fracarolli Nunes

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Understood as the preference for products and services that do not involve moral dilemmas, ethical consumption has been increasingly discussed by scholars, practitioners, and consumers. Among its diverse trends, the defense of animal rights and welfare seems to have gained particular momentum in past decades. Not surprisingly, companies, governments, ideologues, and virtually any institution or group interested in (re)shaping society invest in the building of narratives oriented to influence consumption behavior. The animal rights movement, for example, is devoted to the elimination of the use of animals in science, as well as of commercial animal agriculture and hunting activities. Although advances in ethical consumption may be observed in practice, it still seems more popular as rhetoric. Diverse scholars have addressed the disparities between self-professed ethical consumers and their actual purchase patterns, with differences being attributed to factors such as price sensitivity, lack of information, quality, cynicism, and limited availability. The gap is also linked to the 'consumer sovereignty myth', according to which consumers are only able to choose from a pre-determined range of choices made before products reach them. On the other hand, academics also debate ethical consumption behavior as more likely to occur when it assumes compliance with social norms. As sustainability becomes a permanent issue, customers may tend to adhere to ethical consumption, either because of an individual value or due to a social one. Regardless of these efforts, the actual value attributed to ethical businesses remains unclear. Likewise, the power of stakeholders’ initiatives to influence corporate strategies is dubious. In search to offer new perspectives on these matters, the present study concentrates on the following research questions: Do customers value products/companies that respect animal rights? If so, does such enhanced value convert into actions from the part of the companies? Broadly, we aim to understand if customers’ perception holds performative traits (i.e., are capable of either trigger or contribute to changes in organizational behaviour around the respect for animal rights). In addressing these issues, two preliminary behavioral vignette-based experiments were conducted, with the perspectives of 307 participants being assessed. Building on a case of the cosmetics industry, social, emotional, and functional values were hypothesized as directly impacting positive word-of-mouth, which, in turn, would carry direct effects on purchase intention. A first structural equation model was analyzed with the combined samples of studies I and II. Results suggest that emotional value strongly impacts both positive word-of-mouth and purchase intention. Data confirms initial expectations on customers valuing products and companies that comply with ethical postures concerning animals, especially if social-oriented practices are also present.

Keywords: animal rights, business ethics, emotional value, ethical consumption

Procedia PDF Downloads 116

Authors: Lydia Novozhilova, Vladimir Urazhdin

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An optimization problem for reinforced thin-walled vessels under uniform external pressure is considered. The conventional approaches to optimization generally start with pre-defined geometric parameters of the vessels, and then employ analytic or numeric calculations and/or experimental testing to verify functionality, such as stability under the projected conditions. The proposed approach consists of two steps. First, the feasibility domain will be identified in the multidimensional parameter space. Every point in the feasibility domain defines a design satisfying both geometric and functional constraints. Second, an objective function defined in this domain is formulated and optimized. The broader applicability of the suggested methodology is maximized by implementing the Support Vector Machines (SVM) classification algorithm of machine learning for identification of the feasible design region. Training data for SVM classifier is obtained using the Simulation package of SOLIDWORKS®. Based on the data, the SVM algorithm produces a curvilinear boundary separating admissible and not admissible sets of design parameters with maximal margins. Then optimization of the vessel parameters in the feasibility domain is performed using the standard algorithms for the constrained optimization. As an example, optimization of a ring-stiffened closed cylindrical thin-walled vessel with semi-spherical caps under high external pressure is implemented. As a functional constraint, von Mises stress criterion is used but any other stability constraint admitting mathematical formulation can be incorporated into the proposed approach. Suggested methodology has a good potential for reducing design time for finding optimal parameters of thin-walled vessels under uniform external pressure.

Keywords: design parameters, feasibility domain, von Mises stress criterion, Support Vector Machine (SVM) classifier

Procedia PDF Downloads 322

Authors: Gyo Woo Lee, Man Young Kim

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The blocked-off formulations for the analysis of radiative heat transfer are formulated and examined in order to find the solutions in a two-dimensional complex enclosure. The final discretization equations using the step scheme for spatial differencing practice are proposed with the additional source term to incorporate the blocked-off procedure. After introducing the implementation for inactive region into the general discretization equation, three different problems are examined to find the performance of the solution methods.

Keywords: radiative heat transfer, Finite Volume Method (FVM), blocked-off solution procedure, body-fitted coordinate

Procedia PDF Downloads 291

Authors: Iyai Davies, Olivier L. C. Haas

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In this paper, the problem of stability and stabilization for neutral delay-differential systems with infinite delay is investigated. Using Lyapunov method, new delay-independent sufficient condition for the stability of neutral systems with infinite delay is obtained in terms of linear matrix inequality (LMI). Memory-less state feedback controllers are then designed for the stabilization of the system using the feasible solution of the resulting LMI, which are easily solved using any optimization algorithms. Numerical examples are given to illustrate the results of the proposed methods.

Keywords: infinite delays, Lyapunov method, linear matrix inequality, neutral systems, stability

Procedia PDF Downloads 424

Authors: Jai Prakash, Promod Kumar, Chantel Swart, J. H. Neethling, A. Janse van Vuuren, H. C. Swart

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Ag nanoparticles (NPs) have been used as functional nanomaterials due to their optical and antibacterial properties. Similarly, TiO2 photocatalysts have also been used as suitable nanomaterials for killing cancer cells, viruses and bacteria. Here, we report on multifunctional plasmonic Ag-TiO2 nano-biocomposite synthesized by the sol-gel technique and their optical, surface enhanced Raman scattering (SERS) and antibacterial activities. The as-prepared composites of Ag–TiO2 with different silver content and TiO2 nanopowder were characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersed X-ray analysis (EDX), UV-vis and Raman spectroscopy. The Ag NPs were found to be uniformly distributed and strongly attached to the TiO2 matrix. The novel optical response of the Ag-TiO2 nanocomposites is due to the strong electric field from the surface plasmon excitation of the Ag NPs. The Raman spectrum of Ag-TiO2 nanocomposite was found to be enhanced as compared to TiO2. The enhancement of the low frequency band is evident. This indicates the SERS effect of the TiO2 NPs in close vicinity of Ag NPs. In addition, nanocomposites showed enhancement in the SERS signals of methyl orange (MO) dye molecules with increasing Ag content. The localized electromagnetic field from the surface plasmon excitation of the Ag NPs was responsible for the SERS signals of the TiO2 NPs and MO molecules. The antimicrobial effect of the Ag–TiO2 nanocomposites with different silver content and TiO2 nanopowder were carried out against the bacterium Staphylococcus aureus. The Ag–TiO2 composites showed antibacterial activity towards S. aureus with increasing Ag content as compared to the TiO2 nanopowder. These results foresee promising applications of the functional plasmonic metal−semiconductor based nanobiocomposites for both chemical and biological samples.

Keywords: metal-Semiconductor, nano-Biocomposites, anti-microbial activity, surface enhanced Raman scattering

Procedia PDF Downloads 227

Authors: Leticia Leandro Rade, Amanda Silva de Sousa, Suman Das, Wesley Generoso, Mayara Chagas Ávila, Plinio Salmazo Vieira, Antonio Bonomi, Gabriela Persinoti, Mario Tyago Murakami, Thomas Michael Makris, Leticia Maria Zanphorlin

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Alkenes have an economic appeal, especially in the biofuels field, since they are precursors for drop-in biofuels production, which have similar chemical and physical properties to the conventional fossil fuels, with no oxygen in their composition. After the discovery of the first P450 CYP152 OleTJE in 2011, reported with its unique property of decarboxylating fatty acids (FA), by using hydrogen peroxide as a cofactor and producing 1-alkenes as the main product, the scientific and technological interest in this family of enzymes vastly increased. In this context, the present work presents a new decarboxylase (OleTRN) with low similarity with OleTJE (32%), its biochemical characterization, and structure elucidation. As main results, OleTRN presented a high yield of expression and purity, optimum reaction conditions at 35 °C and pH from 6.5 to 8.0, and higher specificity for oleic acid. Besides that, structure-guided mutations were performed and according to the functional characterizations, it was observed that some mutations presented different specificity and chemoselectivity by varying the chain-length of FA substrates from 12 to 20 carbons. These results are extremely interesting from a biotechnological perspective as those characteristics could diversify the applications and contribute to designing better cytochrome P450 decarboxylases. Considering that peroxygenases have the potential activity of decarboxylating and hydroxylating fatty acids and that the elucidation of the intriguing mechanistic involved in the decarboxylation preferential from OleTJE is still a challenge, the elucidation of OleTRN structure and the functional characterizations of OleTRN and its mutants contribute to new information about CYP152. Besides that, the work also contributed to the discovery of a new decarboxylase with a different selectivity profile from OleTJE, which allows a wide range of applications.

Keywords: P450, decarboxylases, alkenes, biofuels

Procedia PDF Downloads 191

Authors: Khachen Kongpakwattana, Charungthai Dejthevaporn, Orapitchaya Krairit, Piyameth Dilokthornsakul, Devi Mohan, Nathorn Chaiyakunapruk

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Background: Although an increase in the burden of Alzheimer’s disease (AD) is evident worldwide, knowledge of costs and health-related quality of life (HR-QoL) associated with AD in Low- and Middle-Income Countries (LMICs) is still lacking. We, therefore, aimed to collect real-world cost and HR-QoL data, and investigate their associations with multiple disease-severity indicators among AD patients in Thailand. Methods: We recruited AD patients aged ≥ 60 years accompanied by their caregivers at a university-affiliated tertiary hospital. A one-time structured interview was conducted to collect disease-severity indicators, HR-QoL and caregiving information using standardized tools. The hospital’s database was used to retrieve healthcare resource utilization occurred over 6 months preceding the interview date. Costs were annualized and stratified based on cognitive status. Generalized linear models were employed to evaluate determinants of costs and HR-QoL. Results: Among 148 community-dwelling patients, average annual total societal costs of AD care were 8,014 US$ [95% Confidence Interval (95% CI): 7,295 US$ - 8,844 US$] per patient. Total costs of patients with severe stage (9,860 US$; 95% CI: 8,785 US$ - 11,328 US$) were almost twice as high as those of mild stage (5,524 US$; 95% CI: 4,649 US$ - 6,593 US$). The major cost driver was direct medical costs, particularly those incurred by AD prescriptions. Functional status was the strongest determinant for both total costs and patient’s HR-QoL (p-value < 0.001). Conclusions: Our real-world findings suggest the distinct major cost driver which results from expensive AD treatment, emphasizing the demand for country-specific cost evidence. Increases in cognitive and functional status are significantly associated with decreases in total costs of AD care and improvement on patient’s HR-QoL.

Keywords: Alzheimer's disease, associations, costs, disease-severity indicators, health-related quality of life

Procedia PDF Downloads 136

Authors: Sumedha Weerasekara, Morgan Miles, Mark Morrison, Branka Krivokapic-Skoko

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This paper is aimed at exploring the interrelationships among entrepreneurial ecosystem factors and entrepreneurial cognition in regional and metropolitan ecosystems. Entrepreneurial ecosystem factors examined include: culture, infrastructure, access to finance, informal networks, support services, access to universities, and the depth and breadth of the talent pool. Using a multivariate approach we explore the impact of these ecosystem factors or elements on entrepreneurial cognition. In doing so, the existing body of knowledge from the literature on entrepreneurial ecosystem and cognition have been blended to explore the relationship between entrepreneurial ecosystem factors and cognition in a way not hitherto investigated. The concept of the entrepreneurial ecosystem has received increased attention as governments, universities and communities have started to recognize the potential of integrated policies, structures, programs and processes that foster entrepreneurship activities by supporting innovation, productivity and employment growth. The notion of entrepreneurial ecosystems has evolved and grown with the advancement of theoretical research and empirical studies. Importance of incorporating external factors like culture, political environment, and the economic environment within a single framework will enhance the capacity of examining the whole systems functionality to better understand the interaction of the entrepreneurial actors and factors within a single framework. The literature on clusters underplays the role of entrepreneurs and entrepreneurial management in creating and co-creating organizations, markets, and supporting ecosystems. Entrepreneurs are only one actor following a limited set of roles and dependent upon many other factors to thrive. As a consequence, entrepreneurs and relevant authorities should be aware of the other actors and factors with which they engage and rely, and make strategic choices to achieve both self and also collective objectives. The study uses stratified random sampling method to collect survey data from 12 different regions in regional and metropolitan regions of NSW, Australia. A questionnaire was administered online among 512 Small and medium enterprise owners operating their business in selected 12 regions in NSW, Australia. Data were analyzed using descriptive analyzing techniques and partial least squares - structural equation modeling. The findings show that even though there is a significant relationship between each and every entrepreneurial ecosystem factors, there is a weak relationship between most entrepreneurial ecosystem factors and entrepreneurial cognition. In the metropolitan context, the availability of finance and informal networks have the largest impact on entrepreneurial cognition while culture, infrastructure, and support services having the smallest impact and the talent pool and universities having a moderate impact on entrepreneurial cognition. Interestingly, in a regional context, culture, availability of finance, and the talent pool have the highest impact on entrepreneurial cognition, while informal networks having the smallest impact and the remaining factors – infrastructure, universities, and support services have a moderate impact on entrepreneurial cognition. These findings suggest the need for a location-specific strategy for supporting the development of entrepreneurial cognition.

Keywords: academic achievement, colour response card, feedback

Procedia PDF Downloads 141

Authors: G. Olamiti; TK. Takalani; D. Beswa, AIO Jideani

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The study investigated the effects of malting and fermentation times on some chemical, functional properties and microstructural behaviour of Agrigreen, Babala pearl millet cultivars and sorghum flours using response surface methodology (RSM). Central Composite Rotatable Design (CCRD) was performed on two independent variables: malting and fermentation times (h), at intervals of 24, 48, and 72, respectively. The results of dependent parameters such as pH, titratable acidity (TTA), Water absorption capacity (WAC), Oil absorption capacity (OAC), bulk density (BD), dispersibility and microstructural behaviour of the flours studied showed a significant difference in p < 0.05 upon malting and fermentation time. Babala flour exhibited a higher pH value at 4.78 at 48 h malted and 81.9 fermentation times. Agrigreen flour showed a higher TTA value at 0.159% at 81.94 h malted and 48 h fermentation times. WAC content was also higher in malted and fermented Babala flour at 2.37 ml g-1 for 81.94 h malted and 48 h fermentation time. Sorghum flour exhibited the least OAC content at 1.67 ml g-1 at 14 h malted and 48 h fermentation times. Agrigreen flour recorded the least bulk density, at 0.53 g ml-1 for 72 h malted and 24 h fermentation time. Sorghum flour exhibited a higher content of dispersibility, at 56.34%, after 24 h malted and 72 h fermented time. The response surface plots showed that increased malting and fermentation time influenced the dependent parameters. The microstructure behaviour of malting and fermentation times of pearl millet varieties and sorghum flours showed isolated, oval, spherical, or polygonal to smooth surfaces. The optimal processing conditions, such as malting and fermentation time for Agrigreen, were 32.24 h and 63.32 h; 35.18 h and 34.58 h for Babala; and 36.75 h and 47.88 h for sorghum with high desirability of 1.00. The validation of the optimum processing malting and fermentation times (h) on the dependent improved the experimented values. Food processing companies can use the study's findings to improve food processing and quality.

Keywords: Pearl millet, malting, fermentation, microstructural behaviour

Procedia PDF Downloads 62

Authors: H. A. Brandão Cordeiro, M. G. Bocardo, N. C. Penteado, V. T. de Moraes, S. M. Giampietri Lebrão, G. W. Lebrão

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The present study desired to obtain a nanocomposite of epoxy resin reinforced with graphene oxide (OG), for aerospace application, produced by aqueous emulsion. It was obtained proof bodies with 0.00 wt%, 0.10 wt%, 0.25 wt% and 0.50 wt% in weight of nanoparticles, to check the influence of it in the final quality of the obtained product. The validation of the results was done by the application thermal characterization by differential scanning calorimetry (DSC). It was seen that the nanocomposite reinforced with 0.10 wt% of OG showed the best results, the average glass transition temperature, at 2 °C, compared to the pure resin.

Keywords: aqueous emulsion, graphene, nanocomposites, thermal characterization

Procedia PDF Downloads 163

Authors: Bing-Qing Lu, Hui-Tzu Min

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Recent research, supported by sociocultural theory, has shown that collaborative writing in the second language (L2) contexts afford students opportunities to interact with each other to co-construct knowledge during the co-composing process. To date, much research on pair interaction in L2 collaborative writing settings has centered on intermediate and advanced learners by using static categorization of pair interaction patterns. Little is known about the fluid nature of pair interaction during collaborative writing, especially among low-proficiency learners. This study, thus, is aimed to explore the interaction dynamics of low-proficiency L2 learners during collaborative writing via examining the interaction pattern, focus of interaction, and the language related episodes (LREs) of 5 low-proficiency L2 writers from Taiwan. Employing a micro-level functional analytical method to capture the changing nature of pair interaction dynamics, the researchers calculated the number of characters/words produced by each pair member during CW and then classified their utterances into four task related-aspects--content, organization, language use, and task management--to determine each pair member's relative contribution to different dimensions of the evolving text. The LREs were also identified and examined. The results show that, of the five pairs, three pairs changed their interaction patterns when discussing different aspects of writing. Regarding the focus of their interaction, all five pairs paid attention to content most, followed by language use, task management, and organization. They were able to successfully resolve the majority of language issues (75.2%) in LREs and use the correct forms in their writing. These findings lend support to the fluid nature of pairs’ interactions and the changing roles of L2 learners in collaborative writing and highlighted the necessity of examining learners’ interaction patterns from a micro-level perspective. These findings also support previous research that low-proficiency pairs are able to correctly revolve 2/3 of their produced LREs, suggesting that collaborative writing may also be suitable for L2 low-proficiency learners.

Keywords: collaborative writing, low-proficiency L2 learners, micro-level functional analysis, pair interaction pattern

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Authors: Khaled I. Nawafleh

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In this work, we apply the method of Hamilton-Jacobi to obtain solutions of Hamiltonian systems in classical mechanics with two certain structures: the first structure plays a central role in the theory of time-dependent Hamiltonians, whilst the second is used to treat classical Hamiltonians, including dissipation terms. It is proved that the generalization of problems from the calculus of variation methods in the nonstationary case can be obtained naturally in Hamilton-Jacobi formalism. Then, another expression of geometry of the Hamilton Jacobi equation is retrieved for Hamiltonians with time-dependent and frictional terms. Both approaches shall be applied to many physical examples.

Keywords: Hamilton-Jacobi, time dependent lagrangians, dissipative systems, variational principle

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Authors: Rasool Sadeghi, Sayed Mahdi Faghih Imani, Negar Najafi

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The inherent features of Named Data Networking (NDN) provides a robust solution for Internet of Thing (IoT). Therefore, NDN-IoT has emerged as a combined architecture which exploits the benefits of NDN for interconnecting of the heterogeneous objects in IoT. In NDN-IoT, caching schemes are a key role to improve the network performance. In this paper, we consider the effectiveness of cache replacement schemes in NDN-IoT scenarios. We investigate the impact of replacement schemes on average delay, average hop count, and average interest retransmission when replacement schemes are Least Frequently Used (LFU), Least Recently Used (LRU), First-In-First-Out (FIFO) and Random. The simulation results demonstrate that LFU and LRU present a stable performance when the cache size changes. Moreover, the network performance improves when the number of consumers increases.

Keywords: NDN-IoT, cache replacement, performance, ndnSIM

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Authors: Gyoomi Kim, Jiyoung Bae

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The purpose of this study was to propose a framework that verifies the structural relationships among students’ use of digital English learning strategy (DELS), affective domains, and their individual variables. The study developed a hypothetical model based on previous studies on language learning strategy use as well as digital language learning. The participants were 720 Korean high school students and 430 university students. The instrument was a self-response questionnaire that contained 70 question items based on Oxford’s SILL (Strategy Inventory for Language Learning) as well as the previous studies on language learning strategies in digital learning environment in order to measure DELS and affective domains. The collected data were analyzed through structural equation modeling (SEM). This study used quantitative data analysis procedures: Explanatory factor analysis (EFA) and confirmatory factor analysis (CFA). Firstly, the EFA was conducted in order to verify the hypothetical model; the factor analysis was conducted preferentially to identify the underlying relationships between measured variables of DELS and the affective domain in the EFA process. The hypothetical model was established with six indicators of learning strategies (memory, cognitive, compensation, metacognitive, affective, and social strategies) under the latent variable of the use of DELS. In addition, the model included four indicators (self-confidence, interests, self-regulation, and attitude toward digital learning) under the latent variable of learners’ affective domain. Secondly, the CFA was used to determine the suitability of data and research models, so all data from the present study was used to assess model fits. Lastly, the model also included individual learner factors as covariates and five constructs selected were learners’ gender, the level of English proficiency, the duration of English learning, the period of using digital devices, and previous experience of digital English learning. The results verified from SEM analysis proposed a theoretical model that showed the structural relationships between Korean students’ use of DELS and their affective domains. Therefore, the results of this study help ESL/EFL teachers understand how learners use and develop appropriate learning strategies in digital learning contexts. The pedagogical implication and suggestions for the further study will be also presented.

Keywords: Digital English Learning Strategy, DELS, individual variables, learners' affective domains, Structural Equation Modeling, SEM

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Authors: Mustafa M. Donma, Orkide Donma

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Anthropometric measurements are essential for obesity studies. Waist circumference (WC) is the most frequently used measure, and along with hip circumference (HC), it is used in most equations derived for the evaluation of obese individuals. Morbid obesity is the most severe clinical form of obesity, and such individuals may also exhibit some clinical findings leading to metabolic syndrome (MetS). Then, it becomes a requirement to discriminate morbid obese children with (MOMetS+) and without (MOMetS-) MetS. Almost all obesity indices can differentiate obese (OB) children from children with normal body mass index (N-BMI). However, not all of them are capable of making this distinction. A recently introduced anthropometric obesity index, waist circumference + hip circumference/2 ((WC+HC)/2), was confirmed to differ OB children from those with N-BMI, however it has not been tested whether it will find clinical usage for the differential diagnosis of MOMetS+ and MOMetS-. This study was designed to find out the availability of (WC+HC)/2 for the purpose and to compare the possible preponderance of it over some other anthropometric or fat-based obesity indices. Forty-five MOMetS+ and forty-five MOMetS- children were included in the study. Participants have submitted informed consent forms. The study protocol was approved by the Non-interventional Ethics Committee of Tekirdag Namik Kemal University. Anthropometric measurements were performed. Body mass index (BMI), waist-to-hip circumference (W/H), (WC+HC)/2, trunk-to-leg fat ratio (TLFR), trunk-to-appendicular fat ratio (TAFR), trunk fat+leg fat/2 ((trunk+leg fat)/2), diagnostic obesity notation model assessment index-2 (D2I) and fat mass index (FMI) were calculated for both groups. Study data was analyzed statistically, and 0.05 for p value was accepted as the statistical significance degree. Statistically higher BMI, WC, (WC+HC)/2, (trunk+leg fat)/2 values were found in MOMetS+ children than MOMetS- children. No statistically significant difference was detected for W/H, TLFR, TAFR, D2I, and FMI between two groups. The lack of difference between the groups in terms of FMI and D2I pointed out the fact that the recently developed fat-based index; (trunk+leg fat)/2 gives much more valuable information during the evaluation of MOMetS+ and MOMetS- children. Upon evaluation of the correlations, (WC+HC)/2 was strongly correlated with D2I and FMI in both MOMetS+ and MOMetS- groups. Neither D2I nor FMI was correlated with W/H. Strong correlations were calculated between (WC+HC)/2 and (trunk+leg fat)/2 in both MOMetS- (r=0.961; p<0.001) and MOMetS+ (r=0.936; p<0.001) groups. Partial correlations between (WC+HC)/2 and (trunk+leg fat)/2 after controlling the effect of basal metabolic rate were r=0.726; p<0.001 in MOMetS- group and r=0.932; p<0.001 in MOMetS+ group. The correlation in the latter group was higher than the first group. In conclusion, recently developed anthropometric obesity index (WC+HC)/2 and fat-based obesity index (trunk+leg fat)/2 were of preponderance over the previously introduced classical obesity indices such as W/H, D2I and FMI during the differential diagnosis of MOMetS+ and MOMetS- children.

Keywords: children, hip circumference, metabolic syndrome, morbid obesity, waist circumference

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Authors: Aritra Das, Tanmay Mahapatra, Prabir Maharana, Sridhar Srikantiah

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In the absence of adequate well-equipped neonatal-care facilities serving rural Bihar, India, the practice of essential home-based newborn-care remains critically important for reduction of neonatal and infant mortality, especially among pre-term and small-for-gestational-age (Low-birth-weight) newborns. To improve the child health parameters in Bihar, ‘Very-Low-Birth-Weight (vLBW) Tracking’ intervention is being conducted by CARE India, since 2015, targeting public facility-delivered newborns weighing ≤2000g at birth, to improve their identification and provision of immediate post-natal care. To assess the effectiveness of the intervention, 200 public health facilities were randomly selected from all functional public-sector delivery points in Bihar and various outcomes were tracked among the neonates born there. Thus far, one pre-intervention (Feb-Apr’2015-born neonates) and three post-intervention (for Sep-Oct’2015, Sep-Oct’2016 and Sep-Oct’2017-born children) follow-up studies were conducted. In each round, interviews were conducted with the mothers/caregivers of successfully-tracked children to understand outcome, service-coverage and care-seeking during the neonatal period. Data from 171 matched facilities common across all rounds were analyzed using SAS-9.4. Identification of neonates with birth-weight ≤ 2000g improved from 2% at baseline to 3.3%-4% during post-intervention. All indicators pertaining to post-natal home-visits by frontline-workers (FLWs) improved. Significant improvements between baseline and post-intervention rounds were also noted regarding mothers being informed about ‘weak’ child – at the facility (R1 = 25 to R4 = 50%) and at home by FLW (R1 = 19%, to R4 = 30%). Practice of ‘Kangaroo-Mother-Care (KMC)’– an important component of essential newborn care – showed significant improvement in postintervention period compared to baseline in both facility (R1 = 15% to R4 = 31%) and home (R1 = 10% to R4=29%). Increasing trend was noted regarding detection and birth weight-recording of the extremely low-birth-weight newborns (< 1500 g) showed an increasing trend. Moreover, there was a downward trend in mortality across rounds, in each birth-weight strata (< 1500g, 1500-1799g and >= 1800g). After adjustment for the differential distribution of birth-weights, mortality was found to decline significantly from R1 (22.11%) to R4 (11.87%). Significantly declining trend was also observed for both early and late neonatal mortality and morbidities. Multiple regression analysis identified - birth during immediate post-intervention phase as well as that during the maintenance phase, birth weight > 1500g, children of low-parity mothers, receiving visit from FLW in the first week and/or receiving advice on extra care from FLW as predictors of survival during neonatal period among vLBW newborns. vLBW tracking was found to be a successful and sustainable intervention and has already been handed over to the Government.

Keywords: weak newborn tracking, very low birth weight babies, newborn care, community response

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Authors: Tamanna Rimi

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A large body of literature has discussed the determinants of migration decision. However, the potential role of individual risk attitudes on migration decision has so far been overlooked. The research on migration literature has studied how the expected income differential influences migration flows for a risk neutral individual. However, migration takes place when there is no expected income differential or even the variability of income appears as lower than in the current location. This migration puzzle motivates a recent trend in the literature that analyzes how attitudes towards risk influence the decision to migrate. However, the significance of risk attitudes on migration decision has been addressed mostly in a theoretical perspective in the mainstream migration literature. The efficient outcome of labor market and overall economy are largely influenced by migration in many countries. Therefore, attitudes towards risk as a determinant of migration should get more attention in empirical studies. To author’s best knowledge, this is the first study that has examined the relationship between relative risk aversion and migration decision in US market. This paper considers movement across United States as a means of migration. In addition, this paper also explores the network effect due to the increasing size of one’s own ethnic group to a source location on the migration decision and how attitudes towards risk vary with network effect. Two ethnic groups (i.e. Asian and Hispanic) have been considered in this regard. For the empirical estimation, this paper uses two sources of data: 1) U.S. census data for social, economic, and health research, 2010 (IPUMPS) and 2) University of Michigan Health and Retirement Study, 2010 (HRS). In order to measure relative risk aversion, this study uses the ‘Two Sample Two-Stage Instrumental Variable (TS2SIV)’ technique. This is a similar method of Angrist (1990) and Angrist and Kruegers’ (1992) ‘Two Sample Instrumental Variable (TSIV)’ technique. Using a probit model, the empirical investigation yields the following results: (i) risk attitude has a significantly large impact on migration decision where more risk averse people are less likely to migrate; (ii) the impact of risk attitude on migration varies by other demographic characteristics such as age and sex; (iii) people with higher concentration of same ethnic households living in a particular place are expected to migrate less from their current place; (iv) the risk attitudes on migration vary with network effect. The overall findings of this paper relating risk attitude, migration decision and network effect can be a significant contribution addressing the gap between migration theory and empirical study in migration literature.

Keywords: migration, network effect, risk attitude, U.S. market

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Authors: Ajith Kumar S., Sankaran Namboothiri, Sankrish J., SarathKumar S., S. Anil Lal

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A numerical analysis of flow over a heated circular cylinder is done in this paper. The governing equations, Navier-Stokes, and energy equation within the Boussinesq approximation along with continuity equation are solved using hybrid FEM-FVM technique. The density gradient created due to the heating of the cylinder will induce buoyancy force, opposite to the direction of action of acceleration due to gravity, g. In the present work, the flow direction and the direction of buoyancy force are taken as same (vertical flow configuration), so that the buoyancy force accelerates the mean flow past the cylinder. The relative dominance of the buoyancy force over the inertia force is characterized by the Richardson number (Ri), which is one of the parameter that governs the flow dynamics and heat transfer in this analysis. It is well known that above a certain value of Reynolds number, Re (ratio of inertia force over the viscous forces), the unsteady Von Karman vortices can be seen shedding behind the cylinder. The shedding wake patterns could be seriously altered by heating/cooling the cylinder. The non-dimensional shedding frequency called the Strouhal number is found to be increasing as Ri increases. The aerodynamic force coefficients CL and CD are observed to change its value. In the present vertical configuration of flow over the cylinder, as Ri increases, shedding frequency gets increased and suddenly drops down to zero at a critical value of Richardson number. The unsteady vortices turn to steady standing recirculation bubbles behind the cylinder after this critical Richardson number. This phenomenon is well known in literature as "Breakdown of the Karman Vortex Street". It is interesting to see the flow structures on further increase in the Richardson number. On further heating of the cylinder surface, the size of the recirculation bubble decreases without loosing its symmetry about the horizontal axis passing through the center of the cylinder. The separation angle is found to be decreasing with Ri. Finally, we observed a second critical Richardson number, after which the the flow will be attached to the cylinder surface without any wake behind it. The flow structures will be symmetrical not only about the horizontal axis, but also with the vertical axis passing through the center of the cylinder. At this stage, there will be a "single plume" emanating from the rear stagnation point of the cylinder. We also observed the transition of the plume is a strong function of the Richardson number.

Keywords: drag reduction, flow over circular cylinder, flow control, mixed convection flow, vortex shedding, vortex breakdown

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Authors: E. Arcos, E. Bautista, F. Méndez

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In this work, a scaling analysis of the liquefaction phenomena is presented. The characteristic scales are obtained by balancing term by term of the well-known partial dynamics governing equations, (U − P). From the above, the order of magnitude of the horizontal displacement is very smaller compared with the vertical displacement and therefore the governing equation is only a function of the dependent vertical variables. The U − P approximation is reduced and presented in its dimensionless version. This scaling analysis can be used to obtain analytical solutions of the liquefaction phenomena under the action of the water waves.

Keywords: approximation U-P, porous seabed, scaling analysis, water waves

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Authors: Svetlana V. Topolyanskaya, Tatyana A. Eliseeva, Olga N. Vakulenko, Leonid I. Dvoretski

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Introduction: Limited data are available on osteoporosis in centenarians. Therefore, we evaluated bone mineral density in long-living patients with coronary artery disease (CAD). Methods: 202 patients hospitalized with CAD were enrolled in this cross-sectional study. The patients' age ranged from 90 to 101 years. The majority of study participants (64.4%) were women. The main exclusion criteria were any disease or medication that can lead to secondary osteoporosis. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry. Results: Normal lumbar spine BMD was observed in 40.9%, osteoporosis – in 26.9%, osteopenia – in 32.2% of patients. Normal proximal femur BMD values were observed in 21.3%, osteoporosis – in 39.9%, and osteopenia – in 38.8% of patients. Normal femoral neck BMD was registered only in 10.4% of patients, osteoporosis was observed in 60.4%, osteopenia in 29.2%. Significant positive correlation was found between all BMD values and body mass index of patients (p < 0.001). Positive correlation was registered between BMD values and serum uric acid (p=0.0005). The likelihood of normal BMD values with hyperuricemia increased 3.8 times, compared to patients with normal uric acid, who often have osteoporosis (Odds Ratio=3.84; p = 0.009). Positive correlation was registered between all BMD values and body mass index (p < 0.001). Positive correlation between triglycerides levels and T-score (p=0.02), but negative correlation between BMD and HDL-cholesterol (p=0.02) were revealed. Negative correlation between frailty severity and BMD values (p=0.01) was found. Positive correlation between BMD values and functional abilities of patients assessed using Barthel index (r=0,44; p=0,000002) and IADL scale (r=0,36; p=0,00008) was registered. Fractures in history were observed in 27.6% of patients. Conclusions: The study results indicate some features of BMD in long-livers. In the study group, significant relationships were found between bone mineral density on the one hand, and patients' functional abilities on the other. It is advisable to further study the state of bone tissue in long-livers involving a large sample of patients.

Keywords: osteoporosis, bone mineral density, centenarians, coronary artery disease

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Authors: Hend Alrasheed

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Due to their different properties that have led to avoid several limitations of classic client/server systems, there has been a great interest in the development and the improvement of different peer to peer systems. Understanding the properties of complex peer to peer networks is essential for their future improvements. It was shown that the performances of peer to peer protocols are directly related to their underlying topologies. Therefore, multiple efforts have analyzed the topologies of different peer to peer systems. This study presents an overview of major findings of close experimental analyses to different topologies of three unstructured peer to peer systems: BitTorrent, Gnutella, and FreeNet.

Keywords: peer to peer networks, network topology, graph diameter, clustering coefficient, small-world property, random graph, degree distribution

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Authors: Thirupathi Thippani, Kothandaraman Ramanujam

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Current research on energy storage has been paid to metal-air batteries, because of attractive alternate energy source for the future. Metal – air batteries have the probability to significantly increase the power density, decrease the cost of energy storage and also used for a long time due to its high energy density, low-level pollution, light weight. The performance of these batteries mostly restricted by the slow kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on cathode during battery discharge and charge. The ORR and OER are conventionally carried out with precious metals (such as Pt) and metal oxides (such as RuO₂ and IrO₂) as catalysts separately. However, these metal-based catalysts are regularly undergoing some difficulties, including high cost, low selectivity, poor stability and unfavorable to environmental effects. So, in order to develop the active, stable, corrosion resistance and inexpensive bi-functional catalyst material is mandatory for the commercialization of zinc-air rechargeable battery technology. We have attempted and synthesized non-precious metal (NPM) catalysts comprising cobalt and N-doped multiwalled carbon nanotubes (N-MWCNTs-Co) were synthesized by the solid-state pyrolysis (SSP) of melamine with Co₃O₄. N-MWCNTs-Co acts as an excellent electrocatalyst for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), and hence can be used in secondary metal-air batteries and in unitized regenerative fuel cells. It is important to study the OER and ORR at high concentrations of KOH as most of the metal-air batteries employ KOH concentrations > 4M. In the first 16 cycles of the zinc-air battery while using N-MWCNTs-Co, 20 wt.% Pt/C or 20 wt.% IrO₂/C as air electrodes. In the ORR regime (the discharge profile of the zinc-air battery), the cell voltage exhibited by N-MWCNTs-Co was 44 and 83 mV higher (based on 5th cycle) in comparison to of 20 wt.% Pt/C and 20 wt.% IrO₂/C respectively. To demonstrate this promise, a zinc-air battery was assembled and tested at a current density of 0.5 Ag⁻¹ for charge-discharge 100 cycles.

Keywords: oxygen reduction reaction (ORR), oxygen evolution reaction(OER), non-platinum, zinc air battery

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