Examination of the Nonlinear Dynamics and Possible Chaos Encryption in a Zeroth-Order Acousto-Optic Bragg Modulator with Feedback

Zeroth-order chaos modulation in a Bragg cell is examined such that tracking problems due to spatial deflections of the first-order AO beam at the receiver may be avoided by switching to the undeviated zeroth-order beam

A Mixed-Methods Study to Investigate the Awareness by Pilgrims and the Saudi Authorities of Health Risks Arising From the Hajj Pilgrimage in Saudi Arabia

One of the most important factors in developing preventative measures is awareness of health risks among public authorities and the public themselves. The coronavirus pandemic of 2020-2023 has exposed significant weaknesses in public health systems that need to be addressed, although research has so far been limited with respect to studies that have explored the perceptions of both the public and authorities about the uptake of preventative health measures. As it is the host of the annual Hajj pilgrimage, Saudi Arabia offers a good case study of the health management of one of the biggest mass gatherings in the world. Although the health strategy here usually involves an array of preventative measures, the uptake among pilgrims is extremely low. As a case study exploring the factors that determine uptake, the Hajj pilgrimage is approached in this dissertation using a mixed methodology for the collection of data from the officials of the Hajj and the individuals who participate in it. Some 280 participants were canvassed in the quantitative study. The findings are that 94% considered the Hajj to be safe and limited themselves to taking pre-travel advice on health, while 70% of the respondents reported the diversity of the pilgrims to be the main factor threatening health outcomes. Overall, the study reported a significant shortfall in pilgrims’ perception of the health risks associated with the Hajj pilgrimage. Qualitative research was then utilised to collect data from 17 Hajj officials, using semi-structured interviews followed by thematic analysis. The key themes that emerged in the analysis include, first, the safety of the Hajj as perceived by Saudi officials; secondly, in the face of health risks, how the safety of pilgrims is maintained by Saudi officials; thirdly, avoiding the health risks of the Hajj pilgrimage; fourthly holding training sessions for the Hajj workers; fifthly, the pilgrims’ awareness of health risks; sixthly, the education of pilgrims about health risk in their individual countries; and finally, the use of new technologies to raise the pilgrims’ awareness about health instructions and measure their satisfaction regarding the outcomes

Interaction with information in work and everyday life contexts: a qualitative study of the information behaviour of Saudi female academics

This study aims to investigate Saudi female academics’ information behaviour (IB) within their work and everyday life contexts. A qualitative research approach was adopted to investigate the range of information behaviour that the research participants engaged in. The data for this study were collected via in-depth semi-structured interviews and diaries. Participants’ accounts were then subject to a rigorous thematic data analysis process. The research findings indicated that female academics who participated in this study engaged in three main categories of information behaviour: information acquisition, information avoidance, and information sharing. The motivations and the strategies associated with each category have been depicted in a taxonomy of information behaviour. In addition, a detailed analysis of participants’ IB as an action-oriented process has been presented visually, leading to the development of a model that depicts IB as a contextual process. [Continues.

Nonlinear Dynamics of Bragg-domain Acousto-optic Hybrid Feedback for First-order Scattering of Profiled Optical Beams

A series of recent studies involving hybrid acousto-optic (AO) scattering in the Bragg domain under first-order feedback have shown the ability of the AO feedback system to encrypt, transmit and decrypt RF information applied via the sound driver. The basic premise of this operation is founded on the chaotic nature of the hybrid Bragg cell under feedback

Prevalence and predictors of irritable bowel syndrome among medical students and interns in King Abdulaziz University, Jeddah

Background: Irritable bowel syndrome (IBS) is a frequent, costly, and potentially disabling gastrointestinal disorder. Medical education is among the most challenging and the most stressful education, and this may predispose to high rates of IBS.Objective: To determine the prevalence and predictors of IBS among medical students and interns in King Abdulaziz University, Jeddah, Saudi Arabia.Methods: A cross-sectional study was conducted among 597 medical students and interns selected by multistage stratified random sample method in 2012. A confidential, anonymous, and self-administered questionnaire was used to collect personal and sociodemographic data, level of emotional stress, and food hypersensitivity during the past 6 months. Rome III Criteria and the Standardized Hospital Anxiety and Depression Scale were also used.Results: The prevalence of IBS was 31.8%. Multiple logistic regression analysis revealed that the first predictor of IBS was female gender (aOR2.89; 95.0% CI: 1.655.05). The second predictor was presence of morbid anxiety (aOR2.44; 95.0% CI: 1.304.55). Living in a school dormitory, emotional stress during 6 months preceding the study, and the academic year were the next predictors.Conclusions: High prevalence of IBS prevailed among medical students and interns. Female gender, morbid anxiety, living in school dormitory, emotional stress, and higher educational level (grade) were the predictors of IBS. Screening of medical students for IBS, psychological problems, and reducing stress by stress management are recommended.Keywords: epidemiology; irritable bowel syndrome; medical students; Jedda

Information Encryption, Transmission, and Retrieval via Chaotic Modulation in a Hybrid Acousto-optic Bragg Cell under Profiled Beam Illumination

In recent work, the propagation of a profiled optical beam through an open-loop acousto-optic Bragg cell was examined using a transfer function formalism. The device was also studied under closed-loop via intensity feedback, and shown to exhibit more extended chaotic band responses, thereby potentially increasing the dynamic range and parameter sensitivities of any applied signal and the device operation respectively. In this paper, simple low- to mid-RF signals (periodic waveforms and low BW audio) are transmitted through the closed-loop system and the resulting encryption and recovery at the receiver are examined especially from the perspective of overall robustness of the system

Numerical Examination of the Nonlinear Dynamics of a Hybrid Acousto-Optic Bragg Cell with Positive Feedback under Profiled Beam Propagation

In standard weak interaction theory, acousto-optic Bragg analysis typically assumes that the incident light and sound beams are uniform plane waves. Acousto-optic Bragg diffraction with nonuniform profiled input beams is numerically examined under open loop via a transfer function formalism. Unexpected deviations in the first-order diffracted beam from the standard theory are observed for high �� values. These deviations are significant because the corresponding closed-loop system is sensitive to input amplitudes and initial conditions, and the overall impact on the dynamical behavior has not been studied previously in standard analyses. To explore the effect of such nonuniform output profiles on the feedback system, the numerically generated scattered output is fed back to the acoustic driver, and the resulting nonlinear dynamics are manipulated to create novel monostable, bistable, multistable, and chaotic regimes. The effects of the nonuniform input on these regimes are examined using the techniques of Lyapunov exponents and bifurcation maps. The orbital behavior is characterized with quadratic maps, which are an intuitive method of predicting the parametric behavior of the system. The latter trajectory-based approach offers yet a third arm in the process of developing a fuller understanding of the profiled output beam under feedback. The results of this work indicate that the nonlinear dynamical thresholds of the hybrid cell are significantly different for the profiled propagation problem than for the uniform case. The mono and bistable regimes do not coincide with the well-known uniform plane wave results, and the chaotic thresholds, which are critical to understanding encryption applications, are altered noticeably

Secure Transmission and Retrieval of Images in Conjunction with Steganography using Chaos in Nonlinear Acousto-optic Feedback

Digital images are encrypted onto a chaotic carrier in a Bragg cell under hybrid nonlinear feedback and secure data is embedded into the system via steganography. System robustness (with and without channel noise) is analyzed vis-a-vis information security