Polarimetric Modelling for Anisotropic Stars

A theoretical description of the polarization of light, generated by an anisotropic point light source and scattered by an arbitrary shape envelope, is developed in this work, the mechanism of scattering being assumed to be either Thomson or Rayleigh scattering. The description is a development of the earlier work of J. F. L. Simmons' (1982) where he expressed the scattering function and scatterer density distribution function as a summation of multipole contributions. Whereas Simmons analysis was based on an isotropic point light source, the present analysis permits a variable flux to represent the anisotropy of the light source. Thomson or Rayleigh scattering is assumed throughout, and in all cases the scattering envelope is taken to be large compared to the light source. This allows the anisotropy to be expressed in terms of projected area. The model has applicability to rotating, pulsating, binary, and active stars with hot extended envelopes. The thesis is divided into five chapters plus four appendices. Following a review of previous work in Chapter One, together with a discussion of the motivation and interest of stellar polarimetry, in Chapter Two the theoretical analysis is established for scattering polarization with an anisotropic point light source within a spherical envelope. This analysis is then applied to an ellipsoidal black body star within a spherical envelope, for which we get explicit integral expressions for the Stokes' parameters and an analytical solution for the special case of a star with a circular equator. As examples of ellipsoidal stars the polarization from a single distorted star (due to e. g. the rotation) such as Be stars, X-ray binaries filling its Roche lobe (e. g. Cygnus X-1 and Centaurus X-3) , and pulsating stars (pulsating as a series of ellipsoids) is calculated. The latter show a very complicated pattern of qu-loci, which, in principle, fit the polarization behaviour of such types as RV Tau and Omicron Ceti. The maximum polarization of about 20% of the total light is expected from a disk like light source viewed edge on (Galaxies would be good example, since they are very distorted light sources). In Chapter Three the anisotropic light source theory is generalized to include an arbitrarily shaped envelope. In the harmonic summation which results it is found that approximation up to the second order terms is quite acceptable, when both the light source and the envelope are ellipsoidal. The maximum polarization is enhanced (due to the envelope being ellipsoidal) to about 35% when a disk of scatterers is perpendicular to the disk like star observed edge on. In general whether the polarization undergoes enhancement or cancellation is dependent on the angle between the rotation axis of the ellipsoidal star and the axis of symmetry of the ellipsoidal envelope. The effects of rotation and pulsation are also calculated. In Chapter Four the analysis is applied to the case of light source anisotropy arising from a non-uniform photosphere (e. g. hot or cool spot). Calculation of the projected area of the spot as it varies during stellar rotation is done without any of the simplifying assumptions usually made in stellar light curve modelling. Again the approximation of the second order terms of the harmonic summation is acceptable for spots of likely physical size (e. g. of angular extent < 3

Development of virtual network computing (VNC) environment for networking and enhancing user experience

Virtual Network Computing (VNC) is a thin client developed by Real VNC Ltd, Formerly of Olivetti Research Ltd/AT&T labs Cambridge and can be used as a collaborative environment, therefore it has been chosen as the basis of this research study. The purpose of this thesis is to investigate and develop a VNC based environment over the network and to improve the users’ Quality of Experience (QoE) of using VNC between networked groups by the incorporation of videoconferencing with VNC and enhancing QoE in Mobile environments where the network status is far from ideal and is prone to disconnection. This thesis investigates the operation of VNC in different environments and scenarios such as wireless environments by investigating user and device mobility and ways to sustain their seamless connection when in motion. As part of the study I also researched all groups that implement VNC like universities, research groups and laboratories and virtual laboratories. In addition to that I identified the successful features and security measures in VNC in order to create a secure environment. This was achieved by pinpointing the points of strength and weakness in VNC as opposed to popular thin clients and remote control applications and analysing VNC according to conforming to several security measures. Furthermore, it is reasonable to say that the success of any scheme that attempts to deliver desirable levels of Quality of Service (QoS) of an effective application for the future Internet must be based, not only on the progress of technology, but on usersʹ requirements. For instance, a collaborative environment has not yet reached the desired expectation of its users since it is not capable of handling any unexpected events which can result from a sudden disconnection of a nomadic user engaged in an ongoing collaborative session; this is consequently associated with breaking the social dynamics of the group collaborating in the session. Therefore, I have concluded that knowing the social dynamics of application’s users as a group and their requirements and expectations of a successful experience can lead an application designer to exploit technology to autonomously support the initiating and maintaining of social interaction. Moreover, I was able to successfully develop a VNC based environment for networked groups that facilitates the administration of different remote VNC sessions. In addition to a prototype that uses videoconferencing in parallel to VNC to provide a better user’s QoE of VNC. The last part of the thesis was concerned with designing a framework to improve and assess QoE of all users in a collaborative environment where it can be especially applied in the presence of nomadic clients with their much frequent disconnections. I have designed a conceptual algorithm called Improved Collaborative Quality of Experience (IC‐QoE), an algorithm that aims to eliminate frustration and improve QoE of users in a collaborative session in the case of disconnections and examined its use and benefits in real world scenarios such as research teams and implemented a prototype to present the concepts of this algorithm. Finally, I have designed a framework to suggest ways to evaluate this algorithm

The experiences of people with diabetes during covid-19 pandemic lockdown

Little is known about the theoretical foundation underling the response of people with diabetes managing their everyday routines during COVID-19 pandemic lockdown. Aim: To explore the experience of people with diabetes during COVID-19 pandemic lockdown in light of the risk perception, response and behavioral change theories. Method: A qualitative descriptive design was employed, and Braun and Clark’s six step analysis were used for thematic analysis. Semi-structured interviews were conducted online using Zoom Videos Communication. Result: Five themes were defined as follows: (1) perceived the threat and faced their fears, (2) appraised the damage, (3) identified the challenges, (4) modified their routine, and (5) identified the strengths that facilitate the efficacy of their response. There were eight sub-themes within the themes. Conclusion: The results of this study may provide an opportunity for nurses to reflect on issues highlighted by the patients regarding more effective communication, knowledge and skill development for people to support self-care during national emergencies. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Investigation on the influence of waste-based fillers on the mechanical and thermal characteristics of rigid polyurethane foams

An investigation was conducted to analyze the impact of incorporating coal powder particles at different weight ratios (5,&nbsp;10,&nbsp;15,&nbsp;25, and 35) on the mechanical properties and thermal conductivity coefficient of the polyurethane polymer. The thermal conductivity coefficient of the samples was calculated using Holmarc's Lee's Disc apparatus device. The mechanical properties like compressive, tensile, and bending strengths were measured using a universal machine. The results indicated that increasing the coal powder ratio leads to an improvement in the thermal insulation ability due to a decrease in the value of thermal conductivity. Also, the addition of these percentages led to a rise in the values of the mechanical qualities represented by the compressive strength, especially at the ratio of 25&nbsp;wt.&nbsp;%, with a value equal to 2.79&nbsp;MPa (MPa). The flexural resistance and tensile strength increase at a ratio of 35&nbsp;wt.&nbsp;%, with values equal to 20.4&nbsp;MPa and 2.86&nbsp;MPa respectively. The results indicate that the addition of coal powder enhances the ability of thermal conductivity at the ratios (5&nbsp;%, 10)&nbsp;wt.&nbsp;%, with values equal to 0.119&nbsp;W/m ºC and 0.114&nbsp;W/m ºC, respectively, by increasing the thermal conductivities of the samples. The aim of this study is, investigate the effect of filler used coal powder waste on the mechanical and thermal properties of PU. The filler materials show the advantages of recycling waste. Filler influences the morphology and strengthens the brittleness. Additionally, the technology of polyurethane materials conforms to the use of coal powder. The overall amount of energy used to produce PU composites is decreased when waste of filler is used to partially replace petrochemical component

A Rare Sequela of Constriction Band Syndrome: Case Report.

The patient in this case report is a 19-year-old man who presented with left foot cauliflower lesion. He complained of an inability to wear proper shoes, in addition to an unpleasant appearance of his foot. The lesion was present since his birth. Based on history and physical examination, the top 2 differential diagnoses at this stage were pediatric neurofibroma and constriction band syndrome (CBS). Laboratory investigations and x-ray were ordered for the patient. X-ray showed absence of most of the phalanges of the first, second, and third toes, with swelling of the overlying soft tissues of the foot. CBS was confirmed. Excision of the lesion was done along with skin graft applied on the area. Biopsy showed skin with dermal fibrosis and extensive adipose tissue infiltration without any sign of atypia or malignancy. The patient was discharged with regular follow-up appointments

Integration of transcriptome and metabolome provides unique insights to pathways associated with obese breast cancer patients

Information regarding transcriptome and metabolome has significantly contributed to identifying potential therapeutic targets for the management of a variety of cancers. Obesity has profound effects on both cancer cell transcriptome and metabolome that can affect the outcome of cancer therapy. The information regarding the potential effects of obesity on breast cancer (BC) transcriptome, metabolome, and its integration to identify novel pathways related to disease progression are still elusive. We assessed the whole blood transcriptome and serum metabolome, as circulating metabolites, of obese BC patients compared them with non-obese BC patients. In these patients' samples, 186 significant differentially expressed genes (DEGs) were identified, comprising 156 upregulated and 30 downregulated. The expressions of these gene were confirmed by qRT-PCR. Furthermore, 96 deregulated metabolites were identified as untargeted metabolomics in the same group of patients. These detected DEGs and deregulated metabolites enriched in many cellular pathways. Further investigation, by integration analysis between transcriptomics and metabolomics data at the pathway levels, revealed seven unique enriched pathways in obese BC patients when compared with non-obese BC patients, which may provide resistance for BC cells to dodge the circulating immune cells in the blood. In conclusion, this study provides information on the unique pathways altered at transcriptome and metabolome levels in obese BC patients that could provide an important tool for researchers and contribute further to knowledge on the molecular interaction between obesity and BC. Further studies are needed to confirm this and to elucidate the exact underlying mechanism for the effects of obesity on the BC initiation or/and progression

Road safety status during COVID-19 pandemic: exploring public and road safety expert’s opinions

The main objective of this study is to investigate the status of traffic safety and the public perception of traffic safety during the during COVID-19 pandemic. Three different data sets are used in this study: road crash and traffic violation data from Qatar, and two separate questionnaire surveys (from general public and road safety experts). Results showed that during COVID-19 period, the total number of crashes in Qatar significantly reduced during the pandemic compared with the previous 5 years. However, the rates of serious and fatal injuries significantly increased. Regarding the general public perceptions, more than 80% reported that roads became safer while driving behaviours improved during the pandemic. On the other hand, more than 50% of the experts disagreed that roads became safer, 55% disagreed that driving behaviours improved and 70% agreed that less attention from governments was directed toward road safety during the pandemic. The findings from this study could help policy makers to understand the road safety status during the pandemic to make appropriate adjustments in the traffic laws and regulations on a temporary basis. This could help in reducing crash-related injuries and as a result reduce pressure on health and other emergency services.Open Access funding provided by the Qatar National Library. This publication was made possible by the Collaborative Grant [QUCG-CENG-21/22-2] from the Qatar University

Investigation of the Effect of Imatinib and Hydroxyurea Combination Therapy on Hematological Parameters and Gene Expression in Chronic Myeloid Leukemia (CML) Patients

(1) Background: Chronic myeloid leukemia is defined as the neoplastic development of mostly myeloid cells in the bone marrow. Several treatments, including chemotherapy, radiation, hormone treatment, and immunological therapy, can be used to control this condition. The therapeutic impact on leukemic individuals varies, and the response to therapy varies between patients due to disease heterogeneity. The primary goal of this study is to compare the effects of single and Imatinib (IM) and Hydroxyurea (HU) combined treatment on hematological parameters and gene expression in CML patients. (2) Methods: This study was conducted on 51 patients, with chronic myeloid leukemia, who were admitted to Al-Basher hospital in Amman, Jordan, for follow-up. Their hematological parameters were checked and gene expression was measured for (BCL2, PP2A, CIP2A, and WT1). (3) Results: The BCL2 gene was found to be less expressed in both IM and (HU + IM) treatments as compared to the HU group alone, while PP2A gene expression was raised. Such a thing indicates that the outcome of the combined therapy method is not ideal, since PP2A activation causes CML cells to move toward the blast crisis stage. Furthermore, CIP2A gene expression revealed that IM and (HU + IM) had the same therapeutic effect and were more successful in CML patients than HU alone. With regards to the treatment effect on hematological parameters, notably in CML patients in later stages, the combination therapy (HU + IM) raised lymphocyte count, indicating a greater response to the treatment. When compared to single medicines, the combination treatment reduced the proportion of neutrophils to normal reference ranges. Platelet counts, on the other hand, dramatically decreased in both IM and (HU + IM). (4) Conclusion: Because the studied genes (BCL2, PP2A, CIP2A, and WT1) are participating in cell proliferation and death, the findings show that the examined genes are significant to understand the efficacy of various therapies. Furthermore, it was found that there was a clear effect of the clinic-based strategic treatment on hematological indicators such as WBCs, lymphocytes, neutrophils, and platelet counts.Financial support was offered by Al-Ahliyya Amman University/Jordan. Open Access funding provided by the Qatar National Library (QNL)