Search results for: transmission dynamics

Authors: Suchi Barua, Narottam Das, Sven Nordholm, Mohammad Razaghi

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This paper presents nonlinear pulse propagation characteristics for different input optical pulse shapes with various input pulse energy levels in semiconductor optical amplifiers. For simulation of nonlinear pulse propagation, finite-difference beam propagation method is used to solve the nonlinear Schrödinger equation. In this equation, gain spectrum dynamics, gain saturation are taken into account which depends on carrier depletion, carrier heating, spectral-hole burning, group velocity dispersion, self-phase modulation and two photon absorption. From this analysis, we obtained the output waveforms and spectra for different input pulse shapes as well as for different input energies. It shows clearly that the peak position of the output waveforms are shifted toward the leading edge which due to the gain saturation of the SOA for higher input pulse energies. We also analyzed and compared the normalized difference of full-width at half maximum for different input pulse shapes in the SOA.

Keywords: finite-difference beam propagation method, pulse shape, pulse propagation, semiconductor optical amplifier

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Authors: Aniekan James Akpan

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The use of signs and symbols to represent cardinal information is inalienable among African communities. It has been the tenable instrument of cultural transmission for decades, but in the current transposal of Western values, a good number of communicating codes and symbolic images have been gradually relegated to the background. This paper discusses the regeneration of cultural artifacts and sign languages in Nigerian films using Johnpaul Rebecca and Ayamma as models in a qualitative research based on Charles Sanders Pierce's Semiotics as well as quantitative methods of survey using questionnaire and focus group discussion as instruments to obtain data. With a population of 2,343 viewers of the movies used for the study and a sample size of 322 respondents using Philip Meyer’s guide, findings show that cultural relics can stabilise the subject matter of a film. Artifacts can stimulate curiosity and invoke nostalgia. Sign languages encode deeper information that ordinary speech may not properly convey in films. It concludes that the use of non-verbal codes in filmmaking deserves deep research into the culture portrayed and that non-verbal cues communicate deeper information about a people's cosmos in a film than dialogue. It recommends that adequate research should be made before producing a film and the idea of cultural values represented in artifacts and sign language should be ingrained in the courses for students to acquaint themselves with.

Keywords: cultural artifact, Nollywood films, non-verbal communication, sign language

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Authors: Reza Davoodi, Hamid Abbasi, Heidar Norouzi, Gholamabbas Alipourian

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A dynamic model shaping a process of knowledge management (KM) culture change is suggested. It is aimed at providing effective KM of employees for obtaining desired results in an organization. The essential requirements for obtaining KM culture change are determined. The proposed model realizes these requirements. Dynamics of the model are expressed by a change of its parameters. It is adjusted to the dynamic process of KM culture change. Building the model includes elaboration and integration of interconnected components. The “Result” is a central component of the model. This component determines a desired organizational goal and possible directions of its attainment. The “Confront” component engenders constructive confrontation in an organization. For this reason, the employees are prompted toward KM culture change with the purpose of attaining the desired result. The “Assess” component realizes complex assessments of employee proposals by management and peers. The proposals are directed towards attaining the desired result in an organization. The “Reward” component sets the order of assigning rewards to employees based on the assessments of their proposals.

Keywords: knowledge management, organizational culture change, employee, result

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Authors: Rimzhim Gupta, Bhanupriya Boruah, Jayant M. Modak, Giridhar Madras

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Microbial contamination is one of the major concerns in the field of water treatment. AOP (advanced oxidation processes) is well-established method to resolve the issue of removal of contaminants in water. A Z-scheme composite g-C₃N₄/CuWO₄ was synthesized by sol-gel method for the photocatalytic inactivation of a mixed population of Gram-positive bacteria (S. aureus) and Gram-negative bacteria (E. coli). The photoinactivation was observed for different types of bacteria in the same medium together and individually in the absence of the nutrients. The lattice structures and phase purities were determined by X-ray diffraction. For morphological and topographical features, scanning electron microscopy and transmission electron microscopy analyses were carried out. The band edges of the semiconductor (valence band and conduction band) were determined by ultraviolet photoelectron microscopy. The lifetime of the charge carriers and band gap of the semiconductors were determined by time resolved florescence spectroscopy and diffused reflectance spectroscopy, respectively. The effect of weight ratio of C₃N₄ and CuWO₄ was observed by performing photocatalytic experiments. To investigate the exact mechanism and major responsible radicals for photocatalysis, scavenger studies were performed. The rate constants and order of the inactivation reactions were obtained by power law kinetics. For E. coli and S. aureus, the order of reaction and rate constants are 1.15, 0.9 and 1.39 ± 0.03 (CFU/mL)⁻⁰.¹⁵ h⁻¹, 47.95 ± 1.2 (CFU/mL)⁰.¹ h⁻¹, respectively.

Keywords: z-scheme, E. coli, S. aureus, sol-gel

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Authors: Fitri D. Jaswar, Tharek A. Rahman, Yasser A. Ahmad

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CubeSat in low earth orbit (LEO) mainly uses ultra high frequency (UHF) transmitter with fixed radio frequency (RF) output power to download the telemetry and the payload data. The transmitter consumes large amount of electrical energy during the transmission considering the limited satellite size of a CubeSat. A transmitter with power control ability is designed to achieve optimize the signal to noise ratio (SNR) and efficient power consumption. In this paper, the thermal vacuum chamber (TVAC) test is performed to validate the performance of the UHF band transmitter with power control capability. The TVAC is used to simulate the satellite condition in the outer space environment. The TVAC test was conducted at the Laboratory of Spacecraft Environment Interaction Engineering, Kyushu Institute of Technology, Japan. The TVAC test used 4 thermal cycles starting from +60°C to -20°C for the temperature setting. The pressure condition inside chamber was less than 10-5Pa. During the test, the UHF transmitter is integrated in a CubeSat configuration with other CubeSat subsystem such as on board computer (OBC), power module, and satellite structure. The system is validated and verified through its performance in terms of its frequency stability and the RF output power. The UHF band transmitter output power is tested from 0.5W to 2W according the satellite mode of operations and the satellite power limitations. The frequency stability is measured and the performance obtained is less than 2 ppm in the tested operating temperature range. The test demonstrates the RF output power is adjustable in a thermal vacuum condition.

Keywords: communication system, CubeSat, SNR, UHF transmitter

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Authors: Djamil Guettiche, Ahmed Mekki, Tighilt Fatma-Zohra, Rachid Mahmoud

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The aim of this study was to synthesize and characterize conducting polymer composites of polypyrrole and graphene, including pristine and surface-treated graphene (PPy/GO, PPy/rGO, and PPy/rGO-ArCOOH), for use as sensitive elements in a homemade chemiresistive module for on-line detection of nitrogen oxides vapors. The chemiresistive module was prepared, characterized, and evaluated for performance. Structural and morphological characterizations of the composite were carried out using FTIR, Raman spectroscopy, and XRD analyses. After exposure to NO and NO₂ gases in both static and dynamic modes, the sensitivity, selectivity, limit of detection, and response time of the sensor were determined at ambient temperature. The resulting sensor showed high sensitivity, selectivity, and reversibility, with a low limit of detection of 1 ppm. A composite of polypyrrole and graphene functionalized with aryl 4-carboxy benzene diazonium salt was synthesized and characterized using FTIR, scanning electron microscopy, transmission electron microscopy, UV-visible, and X-ray diffraction. The PPy-rGOArCOOH composite exhibited a good electrical resistance response to NO₂ at room temperature and showed enhanced NO₂-sensing properties compared to PPy-rGO thin films. The selectivity and stability of the NO₂ sensor based on the PPy/rGO-ArCOOH nanocomposite were also investigated.

Keywords: conducting polymers, surface treated graphene, diazonium salt, polypyrrole, Nitrogen oxide sensing

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Authors: Marwa M. Abu-Serie, Marwa M. Eltarahony

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The search for reliable, effective, and safe nanoparticles (NPs) as a treatment for cancer is a pressing priority. In this study, Cu-NPs were fabricated by Streptomyces cyaneofuscatus through simultaneous bioreduction strategy of copper nitrate salt. The as-prepared Cu-NPs subjected to structural analysis; energy-dispersive X-ray spectroscopy, elemental mapping, X-ray diffraction, transmission electron microscopy, and ζ-potential. These biological synthesized Cu-NPs were mixed with disulfiram (DS), forming a nanocomplex of Cu-DS with a size of ~135 nm. The prepared nanocomplex (nanoCu-DS) exhibited higher anticancer activity than that of free complex of DS-Cu, Cu-NPs, and DS alone. This was illustrated by the lowest IC50 of nanoCu-DS (< 4 µM) against human breast and liver cancer cell lines comparing with DS-Cu, Cu-NPs, and DS (~8, 22.98-33.51 and 11.95-14.86, respectively). Moreover, flow cytometric analysis confirmed that higher apoptosis percentage range of nanoCu-DS-treated in MDA-MB 231, MCF-7, Huh-7, and HepG-2 cells (51.24-65.28%) than free complex of Cu-DS ( < 4.5%). Regarding inhibition potency of liver and breast cancer cell migration, no significant difference was recorded between free and nanocomplex. Furthermore, nanoCu-DS suppressed gene expression of β-catenine, Akt, and NF-κB and upregulated p53 expression (> 3, >15, > 5 and ≥ 3 folds, respectively) more efficiently than free complex (all ~ 1 fold) in MDA-MB 231 and Huh-7 cells. Our finding proved this prepared nano complex has a powerful anticancer activity relative to free complex, thereby offering a promising cancer treatment.

Keywords: biologically prepared Cu-NPs, breast cancer cell lines, liver cancer cell lines, nanoCu- disulfiram

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Authors: Jyoti Rani, Ashima Anand, Shivendra Shivani

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In recent years, physiological signals obtained in telemedicine have been stored independently from patient information. In addition, people have increasingly turned to mobile devices for information on health-related topics. Major authentication and security issues may arise from this storing, degrading the reliability of diagnostics. This study introduces an approach to reversible watermarking, which ensures security by utilizing the electrocardiogram (ECG) signal as a carrier for embedding patient information. In the proposed work, Pan-Tompkins++ is employed to convert the 1D ECG signal into a 2D signal. The frequency subbands of a signal are extracted using RDWT(Redundant discrete wavelet transform), and then one of the subbands is subjected to MSVD (Multiresolution singular valued decomposition for masking. Finally, the encrypted watermark is embedded within the signal. The experimental results show that the watermarked signal obtained is indistinguishable from the original signals, ensuring the preservation of all diagnostic information. In addition, the DnCNN (Denoising convolutional neural network) concept is used to denoise the retrieved watermark for improved accuracy. The proposed ECG signal-based watermarking method is supported by experimental results and evaluations of its effectiveness. The results of the robustness tests demonstrate that the watermark is susceptible to the most prevalent watermarking attacks.

Keywords: ECG, VMD, watermarking, PanTompkins++, RDWT, DnCNN, MSVD, chaotic encryption, attacks

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Authors: Nutthawadee Jampanil, Kattareeya Kumthip, Niwat Maneekarn, Pattara Khamrin

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Rotavirus A is one of the leading causes of acute gastroenteritis in children younger than five years of age, especially in low-income countries in Africa and South Asia. Two live-attenuated oral rotavirus vaccines, Rotarix and RotaTeq, have been introduced into routine immunization programs in many countries and have proven highly effective in reducing the burden of rotavirus-associated morbidity and mortality. In Thailand, Rotarix and RotaTeq vaccines have been included in the national childhood immunization program since 2020. The objectives of this research are to conduct a molecular epidemiological study and to characterize rotavirus genotypes circulating in pediatric patients with acute diarrhea in Chiang Mai, Thailand, from 2020-2022 after the implementation of rotavirus vaccines. Out of 858 stool specimens, 26 (3.0%) were positive for rotavirus A. G3P[8] (23.0%) was detected as the most predominant genotype, followed by G1P[8] (19.2%), G8P[8] (19.2%), G9P[8] (15.3%), G2P[4] (7.7%), G1P[6] (3.9%), G9P[4] (3.9%), and G8P[X] (3.9%). In addition, the uncommon rotavirus strain G3P[23] (3.9%) was also detected in this study, and this G3P[23] strain displayed a genetic background similar to the porcine rotavirus. In conclusion, there was a dramatic change in the prevalence of rotavirus A infection and the diversity of rotavirus A genotypes in pediatric patients in Chiang Mai, Northern Thailand, in the rotavirus post-vaccination period. The finding obtained from this research contributes to a better understanding of rotavirus epidemiology after rotavirus vaccine introduction. Furthermore, the identification of unusual G and P genotype combination strains provides significant evidence for the potential interspecies transmission between human and animal rotaviruses.

Keywords: rotavirus, infectious disease, gastroenteritis, Thailand

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Authors: Benet Reid, Nina Laurie, Matt Baillie-Smith

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Trans-national and tropical medicine, historically associated with colonial power and missionary activity, is now central to discourses of global health and development, thrust into mainstream media by events like the 2014 Ebola crisis and enshrined in the Sustainable Development Goals. Research in this area remains primarily the province of health professional disciplines, and tends to be framed within a simple North-to-South model of development. The continued role of voluntary work in this field is bound up with a rhetoric of partnering and partnership. We propose, instead, the idea of International Voluntary Health Networks (IVHNs) as a means to de-centre global-North institutions in these debates. Drawing on our empirical work with IVHNs in countries both North and South, we explore geographical and sociological theories for mapping the multiple spatial and conceptual dynamics of power manifested in these phenomena. We make a radical break from conventional views of health as a de-politicised symptom or corollary of social development. In studying health work as it crosses between cultures and contexts, we demonstrate the inextricably political nature of health and health work everywhere.

Keywords: development, global health, power, volunteering

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Authors: Zhuang Guo

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In the field of GaN-based resonant tunneling diodes (RTDs) simulations, the traditional Tsu-Esaki formalism failed to predict the values of peak currents and peak voltages in the simulated current-voltage(J-V) characteristics. The main reason is that due to the strong internal polarization fields, two-dimensional electron gas(2DEG) accumulates at emitters, resulting in 2D-2D resonant tunneling currents, which become the dominant parts of the total J-V characteristics. By comparison, based on the 3D-2D resonant tunneling mechanism, the traditional Tsu-Esaki formalism cannot predict the J-V characteristics correctly. To overcome this shortcoming, we develop a new analytical model for the 2D-2D resonant tunneling currents generated in GaN-based RTDs. Compared with Tsu-Esaki formalism, the new model has made the following modifications: Firstly, considering the Heisenberg uncertainty, the new model corrects the expression of the density of states around the 2DEG eigenenergy levels at emitters so that it could predict the half width at half-maximum(HWHM) of resonant tunneling currents; Secondly, taking into account the effect of bias on wave vectors on the collectors, the new model modifies the expression of the transmission coefficients which could help to get the values of peak currents closer to the experiment data compared with Tsu-Esaki formalism. The new analytical model successfully predicts the J-V characteristics of GaN-based RTDs, and it also reveals more detailed mechanisms of resonant tunneling happened in GaN-based RTDs, which helps to design and fabricate high-performance GaN RTDs.

Keywords: GaN-based resonant tunneling diodes, tsu-esaki formalism, 2D-2D resonant tunneling, heisenberg uncertainty

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Authors: Ruo-Qian Wang

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Open-source CFD has become increasingly popular and promising. The recent progress in multiphase flow enables new CFD applications, which provides an economic and flexible research tool for complex flow problems. Our numerical study using four-way coupling Euler-Lagrangian Large-Eddy Simulations to resolve particle cloud dynamics with OpenFOAM and CFDEM will be introduced: The fractioned Navier-Stokes equations are numerically solved for fluid phase motion, solid phase motion is addressed by Lagrangian tracking for every single particle, and total momentum is conserved by fluid-solid inter-phase coupling. The grid convergence test was performed, which proves the current resolution of the mesh is appropriate. Then, we validated the code by comparing numerical results with experiments in terms of particle cloud settlement and growth. A good comparison was obtained showing reliability of the present numerical schemes. The time and height at phase separations were defined and analyzed for a variety of initial release conditions. Empirical formulas were drawn to fit the results.

Keywords: four-way coupling, dredging, land reclamation, multiphase flows, oil spill

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Authors: Justine Salam

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As a federal state, Canada’s constitutional arrangements regarding the management of natural resources is unique because it gives complete ownership and control of natural resources to the provinces (subnational level). However, the province of Alberta—home to the third largest oil reserves in the world—lags behind comparable jurisdictions in levying royalties on oil corporations, especially oil sands royalties. While Albertans own the oil sands, scholars have argued that natural resource exploitation in Alberta benefits corporations and industry more than it does Albertans. This study provides a systematic understanding of the causal factors affecting royalties in Alberta to map dynamics of power and how they manifest themselves during policy-making. Mounting domestic and global public pressure led Alberta to review its oil sands royalties twice in less than a decade through public-commissioned Royalty Review Panels, first in 2007 and again in 2015. The Panels’ task was to research best practices and to provide policy recommendations to the Government through public consultations with Albertans, industry, non-governmental organizations, and First Nations peoples. Both times, the Panels recommended a relative increase to oil sands royalties. However, irrespective of the Reviews’ recommendations, neither the right-wing 2007 Progressive Conservative Party (PC) nor the left-wing 2015 New Democratic Party (NDP) government—both committed to increase oil sands royalties—increased royalty intake. Why did two consecutive political parties at opposite ends of the political spectrum fail to account for the recommendations put forward by the Panel? Through a qualitative case-study analysis, this study assesses domestic and global causal factors for Alberta’s inability to raise oil sands royalties significantly after the two Reviews through an institutions, interests, and ideas framework. Indeed, causal factors can be global (e.g. market and price fluctuation) or domestic (e.g. oil companies’ influence on the Alberta government). The institutions, interests, and ideas framework is at the intersection of public policy, comparative studies, and political economy literatures, and therefore draws multi-faceted insights into the analysis. To account for institutions, the study proposes to review international trade agreements documents such as the North American Free Trade Agreement (NAFTA) because they have embedded Alberta’s oil sands into American energy security policy and tied Canadian and Albertan oil policy in legal international nods. To account for interests, such as how the oil lobby or the environment lobby can penetrate governmental decision-making spheres, the study draws on the Oil Sands Oral History project, a database of interviews from government officials and oil industry leaders at a pivotal time in Alberta’s oil industry, 2011-2013. Finally, to account for ideas, such as how narratives of Canada as a global ‘energy superpower’ and the importance of ‘energy security’ have dominated and polarized public discourse, the study relies on content analysis of Alberta-based pro-industry newspapers to trace the prevalence of these narratives. By mapping systematically the nods and dynamics of power at play in Alberta, the study sheds light on the factors that influence royalty policy-making in one of the largest industries in Canada.

Keywords: Alberta Canada, natural resources governance, oil sands, political economy

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Authors: Sasan Chalaki, Seyed Ali Mirgholange, Touba Nadri, Saman Chalaki

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In the current world, proper poultry nutrition has garnered special attention as one of the fundamental factors for enhancing their health and performance. Concerns related to the excessive use of antibiotics in the poultry industry and their role in antibiotic resistance have transformed this issue into a global challenge in public health and the environment. On the other hand, poultry farming plays a vital role as a primary source of meat and eggs in human nutrition, and improving their health and performance is crucial. One effective approach to enhance poultry nutrition is the utilization of the antibiotic properties of plant-based ingredients. The use of plant-based alternatives as natural antibiotics in poultry nutrition not only aids in improving poultry health and performance but also plays a significant role in reducing the consumption of synthetic antibiotics and preventing antibiotic resistance-related issues. Plants contain various antibacterial compounds, such as flavonoids, tannins, and essential oils. These compounds are recognized as active agents in combating bacteria. Plant-based antibiotics are compounds extracted from plants with antibacterial properties. They are acknowledged as effective substitutes for chemical antibiotics in poultry diets. The advantages of plant-based antibiotics include reducing the risk of resistance to chemical antibiotics, increasing poultry growth performance, and lowering the risk of disease transmission.

Keywords: poultry, antibiotics, essential oils, plant-based

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Authors: Harun Gülan, Muhsin Tunay Gencoglu, Mehmet Cebeci

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The main function of the insulators used in high voltage (HV) transmission lines is to insulate the energized conductor from the pole and hence from the ground. However, when the insulators fail to perform this insulation function due to various effects, failures occur. The deterioration of the insulation results either from breakdown or surface flashover. The surface flashover is caused by the layer of pollution that forms conductivity on the surface of the insulator, such as salt, carbonaceous compounds, rain, moisture, fog, dew, industrial pollution and desert dust. The source of the majority of failures and interruptions in HV lines is surface flashover. This threatens the continuity of supply and causes significant economic losses. Pollution flashover in HV insulators is still a serious problem that has not been fully resolved. In this study, a water jet test system has been established in order to investigate the behavior of insulators under dirty conditions and to determine their flashover performance. Flashover behavior of the insulators is examined by applying impulse voltages in the test system. This study aims to investigate the insulator behaviour under high impulse voltages. For this purpose, a water jet test system was installed and experimental results were obtained over a real system and analyzed. By using the water jet test system instead of the actual insulator, the damage to the insulator as a result of the flashover that would occur under impulse voltage was prevented. The results of the test system performed an important role in determining the insulator behavior and provided predictability.

Keywords: insulator, pollution flashover, high impulse voltage, water jet model

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Authors: Melissa C. Monney

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Employee morale is an area in which many companies invest millions of dollars, time and effort. Whether these are attributed in benefits or additional monetary compensation, each year, such companies understand that human capital is one of their greatest assets to driving production and revenue. However, with the ever-changing economy, such emphasis on work and production may be counterproductive to employee morale as employees attempt to achieve a healthy work-life balance. A flexible work schedule may be the solution to both companies’ attempt at increasing employee morale and productivity, while affording employees the opportunity to maintain a healthy work-life balance. The information presented in this review derives mostly from research articles, in which the research conducted by means of direct employee feedback through surveys, telephone or face-to-face interviews, or a collection of both, attempted to corroborate (in one way or another) previous research on the largely debated topic of schedule flexibility as the dynamics of economies and families have over the years. This review endeavors to provide a holistic view of schedule flexibility policies, implementation, and perceptions from research in various industries in different countries.

Keywords: flexible scheduling, perceived flexibility, employee morale, productivity

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Authors: D. Makuteniene

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Agriculture, as one of the human activities, emits a significant amount of greenhouse gas emission and undoubtedly has an impact on climate change. The main gaseous products of agricultural greenhouse gases are carbon dioxide, methane, and nitroxadoxide. The sources and emission of these gases depend on land use, soil, crops, manure, livestock, and energy consumption. One of the indicators showing the agricultural impact on climate change is an intensity of GHG emission and its dynamics. This study analyzed the determinants of an intensity of greenhouse gas emission in Lithuanian agriculture using data decomposition. The research revealed that, although greenhouse gas emission increased during the research period, however, agricultural net value added grew more rapidly, which contributed to a reduction of intensity of greenhouse gas emission in Lithuania between 2000 and 2015. It was identified that during the research period intensity of greenhouse gas emission was mostly increased by the change of the use of nitrogen in agriculture, as compared to the change of the area of agricultural land, and by the change of the number of full-time employees, as compared to the change of net value added. Conversely, the change of energy consumption in agriculture, as compared to the change of the use of nitrogen in agriculture, had a bigger impact in decreasing intensity of greenhouse gas emission.

Keywords: agriculture, determinants of intensity, greenhouse gas emission, intensity

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Authors: Jayanti Gyawali, Deepak Adhikari, Mukesh Mallik, Sanjay Sah

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Radiation is defined as an emission or transmission of energy in form of waves or particles through space or material medium. The major imaging tools used in diagnostic radiology is based on the use of ionizing radiation. A cross-sectional study was carried out during July- August, 2015 among technicians in 15 different hospitals of Bharatpur, Chitwan, Nepal to assess awareness regarding radiation protection and their current practice. The researcher was directly engaged for data collection using self-administered semi-structured questionnaire. The findings of the study are presented in socio-demographic characteristics of respondents, current practice of respondents and knowledge regarding radiation protection. The result of this study demonstrated that despite the importance of radiation and its consequent hazards, the level of knowledge among technicians is only 60.23% and their current practice is 76.84%. The difference in the mean score of knowledge and practice might have resulted due to technicians’s regular work and lack of updates. The study also revealed that there is no significant (p>0.05) difference in knowledge level of technicians practicing in different hospitals. But the mean difference in practice scores of different hospital is significant (p<0.05) i.e. i.e. the cancer hospital with large volumes of regular radiological cases and radiation therapies for cancer treatment has better practice in comparison to other hospitals. The deficiency in knowledge of technicians might alter the expected benefits, compared to the risk involved, and can cause erroneous medical diagnosis and radiation hazard. Therefore, this study emphasizes the need for all technicians to update themselves with the appropriate knowledge and current practice about ionizing and non-ionizing radiation.

Keywords: technicians, knowledge, Nepal, radiation

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Authors: Cai J. T. Ladd, Mollie F. Duggan-Edwards, Tjeerd J. Bouma, Jordi F. Pages, Martin W. Skov

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Salt marshes are valued for their role in coastal flood protection, carbon storage, and for supporting biodiverse ecosystems. As a biogeomorphic landscape, marshes evolve through the complex interactions between sea level rise, sediment supply and wave/current forcing, as well as and socio-economic factors. Climate change and direct human modification could lead to a global decline marsh extent if left unchecked. Whilst the processes of saltmarsh erosion and expansion are well understood, empirical evidence on the key drivers of long-term lateral marsh dynamics is lacking. In a GIS, saltmarsh areal extent in 25 estuaries across Great Britain was calculated from historical maps and aerial photographs, at intervals of approximately 30 years between 1846 and 2016. Data on the key perceived drivers of lateral marsh change (namely sea level rise rates, suspended sediment concentration, bedload sediment flux rates, and frequency of both river flood and storm events) were collated from national monitoring centres. Continuous datasets did not extend beyond 1970, therefore predictor variables that best explained rate change of marsh extent between 1970 and 2016 was calculated using a Partial Least Squares Regression model. Information about the spread of Spartina anglica (an invasive marsh plant responsible for marsh expansion around the globe) and coastal engineering works that may have impacted on marsh extent, were also recorded from historical documents and their impacts assessed on long-term, large-scale marsh extent change. Results showed that salt marshes in the northern regions of Great Britain expanded an average of 2.0 ha/yr, whilst marshes in the south eroded an average of -5.3 ha/yr. Spartina invasion and coastal engineering works could not explain these trends since a trend of either expansion or erosion preceded these events. Results from the Partial Least Squares Regression model indicated that the rate of relative sea level rise (RSLR) and availability of suspended sediment concentration (SSC) best explained the patterns of marsh change. RSLR increased from 1.6 to 2.8 mm/yr, as SSC decreased from 404.2 to 78.56 mg/l along the north-to-south gradient of Great Britain, resulting in the shift from marsh expansion to erosion. Regional differences in RSLR and SSC are due to isostatic rebound since deglaciation, and tidal amplitudes respectively. Marshes exposed to low RSLR and high SSC likely leads to sediment accumulation at the coast suitable for colonisation by marsh plants and thus lateral expansion. In contrast, high RSLR with are likely not offset deposition under low SSC, thus average water depth at the marsh edge increases, allowing larger wind-waves to trigger marsh erosion. Current global declines in sediment flux to the coast are likely to diminish the resilience of salt marshes to RSLR. Monitoring and managing suspended sediment supply is not common-place, but may be critical to mitigating coastal impacts from climate change.

Keywords: lateral saltmarsh dynamics, sea level rise, sediment supply, wave forcing

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Authors: S. Perera, T. R. Walsh, M. Solvang

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The structure-property relationships of calcium aluminosilicate (CAS) glass surfaces are of scientific and technological interest regarding dissolution phenomena. Molecular dynamics (MD) simulations can provide atomic-scale insights into the structure and properties of the CAS interfaces in vacuo as the first step to conducting computational dissolution studies on CAS surfaces. However, one limitation to date is that although the bulk properties of CAS glasses have been well studied by MD simulation, corresponding efforts on CAS surface properties are relatively few in number (both theoretical and experimental). Here, a systematic computational protocol to create CAS surfaces in vacuo is developed by evaluating the sensitivity of the resultant surface structure with respect to different factors. Factors such as the relative thickness of the surface layer, the relative thickness of the bulk region, the cooling rate, and the annealing schedule (time and temperature) are explored. Structural features such as ring size distribution, defect concentrations (five-coordinated aluminium (AlV), non-bridging oxygen (NBO), and tri-cluster oxygen (TBO)), and linkage distribution are identified as significant features in dissolution studies.

Keywords: MD simulation, CAS glasses, surface structure, structure-property, CAS interface

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Authors: Zixuan Yang

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This paper presents an analysis of the necessary consideration culture in distributed design through a thorough literature review and case study. The literature review has identified that the need for understanding cultural differences in product design and user evaluations is highlighted by analyzing cross-cultural influences; culture plays a significant role in distributed work, particularly in establishing team cohesion, trust, and credibility early in the project. By applying approaches of Geert Hofstede's dimensions and Fukuyama's trust analysis, a case study of a global design project, i.e., multicultural distributed teamwork solving the problem in terms of reducing the risk of deep vein thrombosis, showcases cultural dynamics, emphasizing trust-building and decision-making. The lessons learned emphasized the importance of cultural awareness, adaptability, and the utilization of scientific theories to enable effective cross-cultural collaborations in global design, providing valuable insights into navigating cultural diversity within design practices.

Keywords: culture, distributed design, global design, Geert Hofstede's dimensions, Fukuyama's trust analysis

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Authors: Hasnaa Benchorfi

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The Tellurite glasses exhibit interesting properties, notably their low melting point (700-900°C), high refractive index (≈2), high transparency in the infrared region (up to 5−6 μm), interesting linear and non-linear optical properties and high rare earth ions solubility. These properties give tellurite glasses a great interest in various optical applications. Transparent ceramics present advantages compared to glasses, such as improved mechanical, thermal and optical properties. But, the elaboration process of these ceramics requires complex sintering conditions. The full crystallization of glass into transparent ceramics is an alternative to circumvent the technical challenges related to the ceramics obtained by conventional processing. In this work, a crystallization study of a specific glass composition in the system TeO2-Ta2O5-Bi2O3 shows structural transitions from the glass to the stabilization of an unreported anti-glass phase to a transparent ceramic upon heating. An anti-glass is a material with a cationic long-range order and a disordered anion sublattice. Thus, the X-ray diffraction patterns show sharp peaks, while the Raman bands are broad and similar to those of the parent glass. The structure and microstructure of the anti-glass and corresponding ceramic were characterized by Powder X-Ray Diffraction, Electron Back Scattered Diffraction, Transmission Electron Microscopy and Raman spectroscopy. The optical properties of the Er3+-doped samples are also discussed.

Keywords: glass, congruent crystallization, anti-glass, glass-ceramic, optics

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Authors: Gouga Hadjer, Djerdali Sofia, Benssaci Ettayeb

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In order to estimate the evolution of the numbers of the aquatic avifauna and their seasonal variations in Sebkhet of Bazer-Sakhra (Site of the eco-complex wetlands of Setif) a monitoring realized during the period from September 2012 to August 2013 allowed to inventory 54 species are spread over 08 orders, 15 families, 34 genres. To follow the global dynamics and the seasonal distribution of species inventoried at Sebkhet Bazer, an analysis of the variation of the total workforce has been established by ecological indices. The autumn season includes the largest number of birds, it totals 3639 individuals. Accidental species are well represented at the autumn and spring seasons denote the interest of the site with respect to migration passages of aquatic birds. During the fall and spring, the Flamingo and the Belon Shelduck are the most abundant with respectively (500, 883) and (560, 1296) individuals. The ecological analysis of this stand showed us that the highest species richness is recorded in spring, (45 species) and the lowest value is obtained in summer it is 20 species.

Keywords: Sebkhet of BazerSakra, ecology, aquatic avifauna, biodiversity, seasonal evolution, wetland

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Authors: Kulwinder Singh Mann, Manmohan Singh Heer, Asha Rani

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The safe storage of radioactive materials has become an important issue. Nuclear engineering necessitates the safe handling of radioactive materials emitting high energy gamma-rays. Hazards involved in handling radioactive materials insist suitable shielded enclosures. With overgrowing use of nuclear energy for meeting the increasing demand of power, there is a need to investigate the shielding behavior of cost effective shielded enclosure (CESE) made from clay-bricks (CB) and fire-bricks (FB). In comparison to the lead-bricks (conventional-shielding), the CESE are the preferred choice in nuclear waste management. The objective behind the present investigation is to evaluate the double layered transmission exposure buildup factors (DLEBF) for gamma-rays for CESE in energy range 0.5-3MeV. For necessary computations of shielding parameters, using existing huge data regarding gamma-rays interaction parameters of all periodic table elements, two computer programs (GRIC-toolkit and BUF-toolkit) have been designed. It has been found that two-layered slabs show effective shielding for gamma-rays in orientation CB followed by FB than the reverse. It has been concluded that the arrangement, FB followed by CB reduces the leakage of scattered gamma-rays from the radioactive source.

Keywords: buildup factor, clay bricks, fire bricks, nuclear wastage management, radiation protective double layered slabs

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Authors: Fekadu L. Bayisa, Elvan Ceyhan, Todd D. Steury

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Interaction between individuals within the same species is an important component of population dynamics. An interaction can be either static (based on spatial overlap) or dynamic (based on movement interactions). Using GPS collar data, we can quantify both static and dynamic interactions between black bears. The goal of this work is to determine the level of black bear interactions using the 95% and 50% home ranges, as well as to model black bear spatial interactions, which could be attraction, avoidance/repulsion, or a lack of interaction at all, to gain new insights and improve our understanding of ecological processes. Recent methodological developments in home range estimation, inhomogeneous multitype/cross-type summary statistics, and envelope testing methods are explored to study the nature of black bear interactions. Our findings, in general, indicate that the black bears of one type in our data set tend to cluster around another type.

Keywords: autocorrelated kernel density estimator, cross-type summary function, inhomogeneous multitype Poisson process, kernel density estimator, minimum convex polygon, pointwise and global envelope tests

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Authors: Abdul Rahman Chamseddine

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The Companions of the Prophet Muhammad, the Sahaba, are regarded as the first link between him and later believers who did not know him or learn from him directly. This makes the Sahaba a link in the chain between God and the ummah (community). Apart from their role in spreading the Prophet’s teachings, they came to be regarded as role models, representing the Islamic ideal of life as prescribed by the Prophet himself. According to Hadith, the Prophet had promised some Sahaba unqualified admission to paradise. It is commonly agreed that the Sahaba have the following attributes in common: God is well pleased with them; they will surely go to paradise; they are perfectly trustworthy; and they are the authorities from whom Muslims can learn all matters related to their religion. No other generation of Muslims has received the attention received by the Companions of the Prophet. In spite of the importance of the Sahaba in Islam, we still know comparatively little about them. There are at least two reasons for this. First, there is the overall scarcity of information surviving from the early period. At the death of the Prophet, it is said, there were more than 100,000 Companions. As we shall see, this is a complex issue, involving the definition of the term Sahaba. However, only few Companions of the Prophet are known to us. Ibn Hajar al-‘Asqalani, who wrote in the fifteenth century A.D., was only able to collect facts about 11,000 of them (including those whose status as Sahaba was disputed). Ibn Sa‘d, Ibn ‘Abd al-Barr and Ibn al-Athir, all of whom lived earlier than Ibn Hajar, included in their respective works fewer lives of Sahaba than he did. If we consider Ibn Hajar’s Isaba as the most complete biographical account of the Sahaba that remains available, we have information, presumably, on approximately one tenth of them. The remaining nine tenths are apparently lost from the historical record. Second, discussion of the Sahaba tends to focus on those considered the most important among them such as ‘Uthman, ‘Ali and Mu‘awiya, while others, who together number in the thousands, are less well-known. This paper will try to study the origins of the term Sahaba that became exclusive to the Companions of the Prophet and not a synonym of the word companions in general.

Keywords: companions, Hadith, Islamic history, Muhammad, Sahaba, transmission

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Authors: Oludamilare Bode Adewuyi, Yanxia Sun, Isaiah Gbadegesin Adebayo

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Voltage stability analysis is crucial to the reliable and economic operation of power systems. The power system of developing nations is more susceptible to failures due to the continuously increasing load demand, which is not matched with generation increase and efficient transmission infrastructures. Thus, most power systems are heavily stressed, and the planning of extra generation from distributed generation sources needs to be efficiently done so as to ensure the security of the power system. Some voltage stability index-based approach for DG siting has been reported in the literature. However, most of the existing voltage stability indices, though sufficient, are found to be inaccurate, especially for overloaded power systems. In this paper, the performance of a relatively different approach using a line voltage stability margin indicator, which has proven to have better accuracy, has been presented and compared with a conventional line voltage stability index for DG siting using the Nigerian 28 bus system. Critical boundary index (CBI) for voltage stability margin estimation was deployed to identify suitable locations for DG placement, and the performance was compared with DG placement using the Novel Line Stability Index (NLSI) approach. From the simulation results, both CBI and NLSI agreed greatly on suitable locations for DG on the test system; while CBI identified bus 18 as the most suitable at system overload, NLSI identified bus 8 to be the most suitable. Considering the effect of the DG placement at the selected buses on the voltage magnitude profile, the result shows that the DG placed on bus 18 identified by CBI improved the performance of the power system better.

Keywords: voltage stability analysis, voltage collapse, voltage stability index, distributed generation

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Authors: Olanrewaju Johnson Akinduntire

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This paper investigates the statistical evaluation of books, citations, articles, journals and other publications in accounting and finance on leveraging technology to mitigate the impact of COVID-19 on business. The research proffers an appraisal of the impact of computerized accounting systems in pre and post pandemic era on activities of the formal and informal sectors, it analyzes the concept of computerized accounting systems, and it seeks to determine the impact of computerized of the overall activities of the informal sector. A special focus of this ICT strategy should be to demystify and promote the diffusion of ICT as a general-purpose technology to the informal sector. It is believed that the use of new technologies can be crucial to meeting the Millennium Development Goals (MDGs) in a timely and effective fashion. Consequent to these, there is a need to prevent the further marginalization of the informal sector by availing ICT services which are mixed appropriately and also properly located. By implication, this will help them access markets and other business information, which can enable or make their economic activities more vibrant and facilitate the availability of information about new opportunities. Conclusively, for one to understand the application of ICT and their locational dynamics in informal sector clusters, there is a need to comprehend and acknowledge the drivers and pressures leading to the adoption of new technology.

Keywords: COVID-19 , (MDGs) , ICT, bibliometric

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Authors: Mohammad Tahir Yousafzai, Nighat Nisar, Rehana Khalil

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The aim of this study is to assess the practices of sharp injuries and factors leading to it among medical practitioners in slum areas of Karachi, Pakistan. A cross sectional study was conducted in slum areas of Landhi Town Karachi. All medical practitioners (317) running the private clinics in the areas were asked to participate in the study. Data was collected on self administered pre-tested structured questionnaires. The frequency with percentage and 95% confidence interval was calculated for at least one sharp injury (SI) in the last one year. The factors leading to sharp injuries were assessed using multiple logistic regressions. About 80% of private medical practitioners consented to participate. Among these 87% were males and 13% were female. The mean age was 38±11 years and mean work experience was 12±9 years. The frequency of at least one sharp injury in the last one year was 27%(95% CI: 22.2-32). Almost 47% of Sharp Injuries were caused by needle recapping, less work experience, less than 14 years of schooling, more than 20 patients per day, administering more than 30 injections per day, reuse of syringes and needle recapping after use were significantly associated with sharp injuries. Injection practices were found inadequate among private medical practitioners in slum areas of Karachi, and the frequency of Sharp Injuries was found high in these areas. There is a risk of occupational transmission of blood borne infections among medical practitioners warranting an urgent need for launching awareness and training on standard precautions for private medical practitioners in the slum areas of Karachi.

Keywords: injection practices, private practitioners, sharp injuries, blood borne infections

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Authors: Brajesh Tiwari, Yuvraj Dangi, Abhishek Jain, Ashok Jain

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The purpose of the investigation was to evaluate the potential of sphingosomes as nanoscale drug delivery units for site-specific delivery of anti-cancer agents. Doxorubicin Hydrochloride (DOX) was selected as a model anti-cancer agent. Sphingosomes were prepared and loaded with DOX and optimized for size and drug loading. The formulations were characterized by Malvern zeta-seizer and Transmission Electron Microscopy (TEM) studies. Sphingosomal formulations were further evaluated for in-vitro drug release study under various pH profiles. The in-vitro drug release study showed an initial rapid release of the drug followed by a slow controlled release. In vivo studies of optimized formulations and free drug were performed on albino rats for comparison of drug plasma concentration. The in- vivo study revealed that the prepared system enabled DOX to have had enhanced circulation time, longer half-life and lower elimination rate kinetics as compared to free drug. Further, it can be interpreted that the formulation would selectively enter highly porous mass of tumor cells and at the same time spare normal tissues. To summarize, the use of sphingosomes as carriers of anti-cancer drugs may prove to be a fascinating approach that would selectively localize in the tumor mass, increasing the therapeutic margin of safety while reducing the side effects associated with anti-cancer agents.

Keywords: sphingosomes, anti-cancer, doxorubicin, formulation

Procedia PDF Downloads 288