Analytic Construction of Periodic Orbits in the Restricted Three-Body Problem

This dissertation explores the analytical solution properties surrounding a nominal periodic orbit in two different planes, the plane of motion of the two primaries and a plane perpendicular to the line joining the two primaries, in the circular restricted three-body problem. Assuming motion can be maintained in the plane and motion of the third body is circular, Jacobi\u27s integral equation can be analytically integrated, yielding a closed-form expression for the period and path expressed with elliptic integral and elliptic function theory. In this case, the third body traverses a circular path with nonuniform speed. In a strict sense, the in-plane assumption cannot be maintained naturally. However, there may be cases where the assumption is approximately maintained over a finite time period. More importantly, the nominal solution can be used as the basis for an iterative analytical solution procedure for the three dimensional periodic trajectory where corrections are computable in closed-form. In addition, the in-plane assumption can be strictly enforced with the application of modulated thrust acceleration. In this case, the required thrust control inputs are found to be nonlinear functions in time. Total velocity increment, required to maintain the nominal orbit, for one complete period of motion of the third body is expressed as a function of the orbit characteristics

Wearable Medical Devices in Use: A Study of Insulin Pump Adoption by Young Diabetic Patients In Saudi Arabia

his research belongs to the multi-disciplinary research community concerned with wearable medical technology and branches of sociology and psychology that study its impact. It addresses a real-life problem of Insulin Pump (IP) adoption by Children. This is important for Saudi Arabia, since it is among the top five countries in the world with the highest rate of diabetes. Theories of reasoned action (TRA), technology acceptance model (TAM) and health belief models (HBM) for some of the cases predict that the perception of benefits is the main motivator for the proper use of the technology. This is often not realised in practice, because the main theoretical focus is on the benefits of IP, specifically in the pre-adoption phase. In contrast, this research project is focused on the reasons why some diabetic children patients misuse the IP in spite of the initial perception of its benefits. To find answers to this research question, an empirical study of adoption of IP by children and young adults in Saudi Arabia was carried out. A novel analytical framework was developed in this study in order to unify different perspectives and expectations of the benefits of the IP for a diabetic child and young adult. The analytic framework is applied using empirical study of diabetic children struggling with the IP in the course of the adoption process, with main emphasis on the post-adoption phase. Research methods were predominantly qualitative, involving in-depth interviews and case studies. In the discovery phase, data was collected through interviews of medical personnel and case studies with children and their parents. The analysis was focused on different interactions between medical personnel, patients and their caregivers, the discourses among them in order to explicate the contradictions between them. The main findings are that contradictions show different expectations between the different actors. The medical personnel used medical reasons, whereas the caregiver focus on emotional aspects. However, the diabetic child was concerned with the life-style changes that the use of the IP caused. The different motivations create misunderstandings and result in resistance towards the IP. Age-related and culture-specific factors were also considered, but further research is needed to ensure that the findings can be generalised to other devices, age-groups, cultures and different social contexts. Such studies would also refine the analytical framework and enrich research methodology to make generalisations possible

Mechanical Properties of HPC Incorporating Fly Ash and Ground Granulated Blast Furnace Slag After Exposure to High Temperatures

The behavior of concrete structures after being exposed to elevated temperatures is considered one of the great vital concerns in Civil Engineering. Moreover, as elevated temperature have adverse effects on the mechanical properties of concrete members, it’s important to find solutions to improve these properties at elevated temperature. This study aims to investigate the effect of supplementary cementitious materials (SCM) on the high performance concrete (HPC) compressive, tensile, and flexural strengths after exposure to different temperatures of 200 °C, 400 °C, 600 °C, and 800 °C. In preparing HPC, different parameters were considered including SCM type, fly ash (FA) or ground granulated blast furnace slag (GGBFS), adding 0.5% (by volume fraction) steel fiber (SF), polypropylene fiber (PP) and hybrid fibers. The results were compared with those for high strength concrete (HSC) and normal strength concrete (NSC). The results showed that using FA and GGBFS, SF, and hybrid fibers can significantly improve the residual mechanical properties of HPC, while using PP fiber has an adverse effect on the residual mechanical properties of HPC especially residual tensile and flexural strengths. The standard code curves underestimate the residual mechanical properties of HPC after 200 °C

Hotel Employees’ Attitude and Acceptance Toward Human-Robot Co-Working Based on the Industry 5.0 Concept

Received 21 July 2022. Accepted 31 October 2022. Published online 30 December 2022.The emergence of AI-powered machines and robotics technology has strongly influenced the service industry, especially the hotel business. The effects of their introduction to the work environment on the human workforce have been a subject of much debate. However, practical studies in this regard are relatively limited. Therefore, this study investigates the employees’ attitude and acceptance toward working alongside robots in a sample of employees working in luxury hotels in Yekaterinburg, Russia. This study employed a self-administered questionnaire as the data collection instrument. Two hundred questionnaire forms were distributed. Among them, 167 forms were completed and valid for analysis. Data were analyzed descriptively using IBM SPSS (Version 28). The findings revealed that, although the employees agreed to interact with robots and indicated that robots are helpful, enjoyable, and productive, they also pointed out that robots would control jobs. Besides, the extensive introduction of robots will lead to social issues such as losing contact with humans. The study conclusion has practical implications for hotel managers and can guide further research for academics.The researcher (Khaled Ghazy) is funded by a scholarship under the joint (executive program between the Arab Republic of Egypt and Russia)

Extraction and characterization of Nanocellulose obtained from sugarcane bagasse as agro-waste

This study aimed to characterize nanocellulose extracted from sugarcane bagasse (SCB) by acid hydrolysis 60% (w/w) H2SO4 at 45 â—¦C. The effect of hydrolysis time (20, 30 and 40 min) on the structure and properties of the nanofibers was investigated. Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) results indicated that the hemicellulose and lignin were removed extensively in the cellulose whiskers. The morphology and dimensions of the fibers and acid-released cellulose nanowhisker (CNW) were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that SCB could be used as source to obtain cellulose whiskers and they had needle-like structures. Longer hydrolysis time produced a lower yield of nanofibers; whereas the degree of crystallinity increased from 38.22% to 65.37% with increasing hydrolysis time due to removal of amorphous cellulose

Ion Flotation of Copper(II) and Lead(II) from Environmental Water Samples

The present study aims to develop a simple, rapid and economic procedure for copper(II) and lead(II) removal under the optimum conditions investigated. It is based on the complex formation between Cu2+ and Pb2+ ions and diphenylcarbazone (HDPC) followed by flotation with oleic acid (HOL) surfactant. The different parameters (namely: solution pH, HDPC, HOL, copper and lead concentrations, ionic strength, temperature and the presence of foreign ions) influencing the flotation process were examined. Nearly, 100% of Cu2+ and Pb2+ ions were removed from aqueous solutions at pHs 6 and 7, respectively at room temperature (~25 \ub0C). The procedure was successfully applied to recover almost copper(II) and lead(II) spiked to some natural water samples. Due to the rapid, simple and economic nature of the procedure, a flotation mechanism is suggested for metal removal in wastewater systems

Pattern of cesarean deliveries among women in an urban and rural district in Egypt

Aim: to compare patterns of delivery at an urban and a rural district in Egypt over 3 years. Methods: This retrospective study included 500 women and 50 obstetricians from each district from January, 2013 till December, 2015. Women answered a questionnaire about their deliveries. Obstetricians answered a questionnaire about their practiceof CS. Results: CS rate in the rural district was 57.2% compared to 54.8% in the urban district in 2013. In 2014 and 2015, CS rates increased to 65.3% and 69%, respectively in the rural district compared to 56% and 57.7%, respectively in the urban district. 66% of obstetricians in the rural district performed CS for more than 50% of their patients compared to 76% of obstetricians in the urban district. 52% and 4% of obstetricians in the rural and urban districts, respectively, performed CS upon maternal request. 70.3% of women in the rural district who delivered by CS preferred to deliver vaginally. 51.4% of urban women who delivered by CS preferred to deliver vaginally. Level of education was the only factor showing statistical significance. Conclusion: CS rates increased over time with higher rates in the rural area. Level of women's education was the only factor affecting delivery choice. Keywords: Cesarean sections; CS rate; urban area; rural area; Egypt; obstetricians

An Extracted Fraction of Pseudomonas Oleovorans Can Inhibit Viral Entry and RNA Replication of Hepatitis C Virus in Cell Culture

The emergence and distribution of Hepatitis C virus (HCV) infection is still considered as an unsolved problem. Due to side effects, many synthetic drugs have been avoided and replaced by new biologically derived ones. Aim of this study was to use Pseudomonas oleovorans’ extract as HCV viral replication inhibition agent in cell culture system. Several factors were studied and the optimum growth conditions were selected for maximum production of antiviral substance. Pseudomonas oleovorans’ extract was fractionated using different concentrations of chloroform: methanol on silica gel columns. Analysis of potent fraction by GC/MS showed of tetradecanoic and hexadecanoic acid methyl esters. The selected fraction was tested against HCV in vitro using two different protocols: viral attachment entry inhibition (Pre-incubation) and viral replication inhibition (Post infection). 0.1 µg / ml of the selected antiviral fraction resulted in inhibition of viral replication in Huh 7.5 cells. However, higher concentration of 100 µg / ml did not cause any viral inhibition. The selected bacterial fraction containing tetradecanoic acid and hexadecanoic acid methyl esters could be used as a promising candidate to inhibit viral HCV entry and replication of HCV

Liposome co-incubation with cancer cells secreted exosomes (extracellular vesicles) with different proteins expressions and different uptake pathways

We recently showed that in vitro incubation of cells with liposomes of varying compositions can increase exosome secretion and increase the yield of harvested exosomes (extracellular vesicles, EVs). This might foster their potential therapeutic implementations. In the current study, we investigated the surface proteins and the uptake of the harvested exosomes (EVs) to see if the incubation of cells with liposomes would change the biological properties of these exosomes (EVs). Interestingly, exosomes (EVs) induced by solid cationic liposomes lacked some major exosome marker proteins such as CD9, flotillin-1, annexin-A2 and EGF, and subsequently had lower levels of cellular uptake upon re-incubation with donor cancer cells. However, exosomes (EVs) induced under normal condition and by fluid cationic liposomes, displayed the entire spectrum of proteins, and exhibited higher uptake by the donor cancer cells. Although endocytosis was the major uptake pathway of exosomes (EVs) by tumor cells, endocytosis could occur via more than one mechanism. Higher exosome uptake was observed in donor B16BL6 cells than in allogeneic C26 cells, indicating that donor cells might interact specifically with their exosomes (EVs) and avidly internalize them. Taken together, these results suggest a technique for controlling the characteristics of secreted exosomes (EVs) by incubating donor cancer cells with liposomes of varying physiochemical properties