The problem of matrix projective synchronization (MPS) in discrete-time chaotic systems is investigated, and a new type of discrete chaos synchronization called inverse matrix projective synchronization (IMPS) is introduced. Sufficient conditions are derived for achieving MPS and IMPS between chaotic dynamical systems in discrete-time of different and identical dimensions. Based on new control schemes, Lyapunov stability theory, and stability theory of linear dynamical systems in discrete-time, some synchronization criteria are obtained. Numerical examples and simulations are used to illustrate the use of the proposed schemes.

Introduction. Middle East respiratory syndrome coronavirus was first recognized in September 2012 in Saudi Arabia. The clinical presentations of MERS and non‐MERS SARI are often similar. Therefore, the identification of suspected cases that may have higher chances of being diagnosed as cases of MERS‐CoV is essential. However, the real challenge is to flag these patients through some demographic markers. The nature of these markers has not previously been investigated in Saudi Arabia, and hence, this study aims to identify them. Methods. It was a surveillance system‐based study, for which data from a total of 23,646 suspected patients in Riyadh and Al Qassim regions were analyzed from January 2017 until December 2017 to estimate the prevalence of MERS‐CoV among suspected cases and to determine potential demographic risk factors related to the confirmation of the diagnosis. Results. Of 23,646 suspected cases, 119 (0.5%) were confirmed by laboratory results. These confirmed cases (67.2% of which were males) had a mean age of 43.23 years (SD ± 22.8). Around 42.2% of the confirmed cases were aged between 41 and 60 years and about 47% of confirmed cases had their suspected specimen tested in the summer. The study identified three significant and independent predictors for confirmation of the disease: an age between 41 and 60 years, male gender, and summer season admission. Conclusion. The study provides evidence that the MERS‐CoV epidemic in the subject regions has specific characteristics that might help future plans for the prevention and management of such a contagious disease. Future studies should aim to confirm such findings in other regions of Saudi Arabia as well and explore potential preventable risk factors.

Psychological disorders are one of the leading causes of disability globally. Evidence suggests the positive role of physical activity on physical and mental health in various countries. However, a limited number of studies have been done in Saudi Arabia to investigate the association between physical activity and psychological health, especially among women. The objective of the study was to identify the prevalence of depression, stress, anxiety, and physical activity as well as examine the association between depression, anxiety, stress, and social support in relation to physical activity among Saudi women at Princess Nourah Bint Abdulrahman University (PNU). A total of 712 Saudi students and staff from PNU, with a mean (SD) age of 20.59(5.30), voluntarily completed an electronic-based questionnaire, which included three validated scales in the Arabic language: The Depression, Anxiety and Stress Scale - 21 Items (DASS-21), Global Physical Activity Questionnaire (GPAQ), and Medical Outcomes Study (MOS) social support. The results of this cross-sectional study showed that the prevalence of depression, anxiety, and stress were 24%, 31%, and 22.1%, respectively. Levels of physical activity were not associated with psychological disorders while sedentary time was strongly correlated with depression, anxiety, and stress (p<0.001). Emotional support, affectionate support, and positive social interaction were negatively correlated with depression (p<0.05). The findings indicate that stress, depression, and anxiety were relatively common among Saudi females, especially among young ages, and that social support was a significant protective factor of depression. Community-based psychological health prevention programs and social support groups are needed to address these issues. The second major finding was that 51% of the participants were insufficiently active and 61% were having a sedentary lifestyle. Depression, anxiety, and stress scores are strongly correlated with sedentary time, which highlights the need for establishing a national policy that encourages active living and discourages sedentary behavior.