Global Stability of Positive Discrete-time Time-varying Nonlinear Feedback Systems

The global stability of positive discrete-time time-varying nonlinear systems with time-varying scalar feedbacks is investigated. Sufficient conditions for the asymptotic stability of discrete-time positive time-varying linear systems are given. The new conditions are applied to discrete-time positive time-varying nonlinear systems with time-varying feedbacks. Sufficient conditions are established for the global stability of the discrete-time positive time-varying nonlinear systems with feedbacks.

Monsoon onset and reservoir build up- A case Study for Hirakud

Onset of monsoon for each year of the period from 1961 to 1986 over the Upper Mahanadi basin has been studied taking into consideration the sharp increase in water levels of the Hirakud reservoir. This study has shown that .there are positive and negative time-lags in the arrival of monsoon run off into the reservoir. It has been seen that positive time lags are due to antecedent condition of the basin before the onset of monsoon while negative time-lag appears to be due to pre-monsoon thunderstorm activity which causes reservoir levels to increase before the onset of monsoon. Attempt has been made to discuss all these cases briefly. It has been seen that on a majority of occasions monsoon runoff has reached the reservoir with a time-lag of 1 to 4 days.

Finite-Time Boundedness of Linear Uncertain Switched Positive Time-Varying Delay Systems with Finite-Time Unbounded Subsystems and Exogenous Disturbance

The problem of finite-time boundedness for a class of linear switched positive time-varying delay systems with interval uncertainties and exogenous disturbance is addressed. This characteristic research is that the studied systems include the finite-time bounded subsystems and finite-time unbounded subsystems. Both a slow mode-dependent average dwell time and a fast mode-dependent average dwell time switching techniques are utilized reasonably. And by applying a copositive Lyapunov-Krasovskii functional, novel delay-dependent sufficient criteria are derived to guarantee such systems to be finite-time bounded concerning the given parameters and designed switching signal. Furthermore, new finite-time boundedness criteria of the systems without interval uncertainties are also obtained. Finally, the efficiency of the theoretical results is presented in two illustrative examples.

Ricci flow on manifolds with boundary with arbitrary initial metric

In this paper, we study the Ricci flow on manifolds with boundary. In the paper, we substantially improve Shen’s result [Y. Shen, On Ricci deformation of a Riemannian metric on manifold with boundary, Pacific J. Math. 173 1996, 1, 203–221] to manifolds with arbitrary initial metric. We prove short-time existence and uniqueness of the solution, in which the boundary becomes instantaneously totally geodesic for positive time. Moreover, we prove that the flow we constructed preserves natural boundary conditions. More specifically, if the initial metric has a convex boundary, then the flow preserves positive curvature operator and the PIC1, PIC2 conditions. Moreover, if the initial metric has a two-convex boundary, then the flow preserves the PIC condition.

Time Perspective, Hope and Self-Regulation among Preparatory Year University Students: Exploring the Connections

This study aimed to investigate the relationship between time perspective, hope and self-regulation among foundation year students at a Malaysian public university. A survey questionnaire on the three constructs was completed by 118 Malay students aged between 18 to 21. The findings showed a significant positive correlation between the future time perspective and self-regulation (r = 0.251, p = 0.007). However, the association is a weak one. Likewise, a significant relationship was found between hope and two of the temporal orientations, i.e., the future orientation (r = 0.399, p = 0.001) and the past positive at r = 0.271, p = 0.003., which is also considered a weak relationship. However, no significant association was observed between the past positive time perspective and students’ self-regulation. On the contrary, the past negative and present-fatalistic time orientations have a significant negative relation with hope at r = - 0.308, p = 0.001 and r = - 0.207, p = 0.028, respectively. A similar result was obtained for the association between self-regulation and the PN orientation at r = - 0.290, p = 0.002. It was also found that hope and students’ self-regulation are strongly correlated (r = 0.268, p = 0.004). In essence, the results imply that students with a high future time orientation are likely to have high levels of hope and self-regulation. Therefore, time perspective, especially the future orientation, and self-regulation skills could be important intervention factors for addressing students’ academic obstacles. The findings of this study are beneficial for counselors, educators, and supervisors in designing intervention programs to help students become more positive and optimistic individuals.

Effects of a Dosed Exercise Intervention in Craving and Anhedonia: A Secondary Analysis from the STRIDE-CTN 0037 Clinical Trial

This is a secondary analysis from the project “CTN-0037-Stimulant Reduction Intervention Using Dosed Exercise (STRIDE)”. We aimed to test the effects of a Vigorous Intensity High Dose Exercise Augmentation (VIHD) when compared to a health education intervention (HEI) in stimulant drug-cravings and anhedonia. Three-hundred and two participants were randomized (VIHD = 152, DEI =150). No significant Time x Treatment interaction was found neither for craving nor anhedonia. For craving scores, a positive Time and negative Age effects were found. The results suggest that craving increases over time, and that younger individuals had higher craving scores across the trial. In the case of anhedonia scores, Gender had a positive direct effect, and the interaction Time x Gender had a negative effect. . Weighting the current evidence about exercise interventions for substance use, is possible that a particular patient profile and high adherence are required to be successful. Future research should focus on the identification of variables to identify who could benefit from systematic exercise programs.

The Construction of Positive Social Psychology During the COVID-19 Pandemic: Exploring the Relationship Between Social Support and Peace of Mind Through a Three-Wave Longitudinal Cross-Lag Study

The ongoing COVID-19 pandemic has sparked a major global crisis that has infected public social mentality. Drawing on the concept of peace of mind (PoM), a culture-specific positive emotion construct developed in the Chinese cultural context, this study explored the ways to build a positive public social mentality in the time of the pandemic. PoM is indicative of a calm and stable emotional state marked by self-control and spiritual cultivation and is believed to align with the perceptions of subjective well-being in Chinese or eastern cultures. A three-wave cross-lag study using an online questionnaire survey was conducted on 107 employees in Chinese enterprises during the pandemic. The research findings suggest that social support had a significant positive time-cross effect on later PoM, i.e., social support-T1 had a significant predictive effect on PoM-T2 (β = 0.16, SE = 0.09, p < 0.05) and social support-T2 had a significant predictive effect on PoM-T3 (β = 0.38, SE = 0.19, p < 0.05), whereas PoM failed to show a positive time-cross effect on later social support, i.e., the predictive effects of PoM-T1 on social support-T2 (β = 0.04, SE = 0.07, p > 0.05) and of PoM-T2 on social support-T3 (β = 0.13, SE = 0.09, p > 0.05) were not significant. This study provided a dynamic picture of the construction of public social mentality in the time of public health emergencies and also contributed to the research on PoM antecedents.