Secure Downlink Transmission Strategies against Active Eavesdropping in NOMA Systems:A Zero-Sum Game Approach

Non-orthogonal multiple access technology(NOMA),as a potentially promising technology in the 5G/B5G era,suffers fromubiquitous security threats due to the broadcast nature of the wirelessmedium.In this paper,we focus on artificial-signal-assisted and relay-assisted secure downlink transmission schemes against external eavesdropping in the context of physical layer security,respectively.To characterize the non-cooperative confrontation around the secrecy rate between the legitimate communication party and the eavesdropper,their interactions are modeled as a two-person zero-sum game.The existence of the Nash equilibrium of the proposed game models is proved,and the pure strategyNash equilibriumand mixed-strategyNash equilibriumprofiles in the two schemes are solved and analyzed,respectively.The numerical simulations are conducted to validate the analytical results,and showthat the two schemes improve the secrecy rate and further enhance the physical layer security performance of NOMA systems.

A survey on monocular 3D human pose estimation

Recovering human pose from RGB images and videos has drawn increasing attention in recent years owing to minimum sensor requirements and applicability in diverse fields such as human-computer interaction,robotics,video analytics,and augmented reality.Although a large amount of work has been devoted to this field,3D human pose estimation based on monocular images or videos remains a very challenging task due to a variety of difficulties such as depth ambiguities,occlusion,background clutters,and lack of training data.In this survey,we summarize recent advances in monocular 3D human pose estimation.We provide a general taxonomy to cover existing approaches and analyze their capabilities and limitations.We also present a summary of extensively used datasets and metrics,and provide a quantitative comparison of some representative methods.Finally,we conclude with a discussion on realistic challenges and open problems for future research directions.

Childhood sleep:physical,cognitive,and behavioral consequences and implications

Background Sleep problems in children have been increasingly recognized as a major public health issue.Previous research has extensively studied and presented many risk factors and potential mechanisms for children’s sleep problems.In this paper,we aimed to identify and summarize the consequences and implications of child sleep problems.Data sources A comprehensive search for relevant English language full-text,peer-reviewed publications was performed focusing on pediatric sleep studies from prenatal to childhood and adolescence in a variety of indexes in PubMed,SCOPUS,and Psych Info published in the past two decades.Both relevant data-based articles and systematic reviews are included.Results Many adverse consequences are associated with child sleep deficiency and other sleep problems,including physical outcomes(e.g.,obesity),neurocognitive outcomes(e.g.,memory and attention,intelligence,academic performance),and emotional and behavioral outcomes(e.g.,internalizing/externalizing behaviors,behavioral disorders).Current prevention and intervention approaches to address childhood sleep problems include nutrition,exercise,cognitive–behavioral therapy for insomnia,aromatherapy,acupressure,and mindfulness.These interventions may be particularly important in the context of coronavirus disease 2019.Specific research and policy strategies can target the risk factors of child sleep as well as the efficacy and accessibility of treatments.Conclusions Given the increasing prevalence of child sleep problems,which have been shown to affect children’s physical and neurobehavioral wellbeing,understanding the multi-aspect consequences and intervention programs for childhood sleep is important to inform future research direction as well as a public health practice for sleep screening and intervention,thus improving sleep-related child development and health.

Childhood sleep:assessments,risk factors,and potential mechanisms

Background Sleep problem is a highly prevalent health issue among pediatric populations across the world.In this review,we aimed to identify risk factors contributing to sleep deficiency and poor sleep hygiene in children.Potential biological,psychosocial,and environmental mechanisms as well as research gaps in the literature are also discussed.Data sources A comprehensive search for relevant English language full-text,peer-reviewed publications was performed focusing on pediatric sleep studies from prenatal to childhood and adolescence in a variety of indexes in PubMed,SCOPUS,and Psych Info.Both relevant data based and systematic reviews are included.Results This paper summarizes many risk factors for childhood sleep problems,including biological(e.g.,genetics,gender,age and puberty,prenatal factors,postnatal factors);nutritional(e.g.,macronutrients,micronutrients,omega-3 fatty acids,obesity);environmental(e.g.,heavy metals,noise,light,air pollution);interpersonal(e.g.,family,exposure to violence,screen media use,physical injury);and community/socioeconomic variables(e.g.,racial/ethnicity and cultural factors,neighborhood conditions and socioeconomic status,school factors,public health disasters/emergencies),to better understand the development of sleep problems in children.Conclusions Poor childhood sleep is a multifactorial issue affected by a wide range of prenatal and early-life biological,environmental,and psychosocial risk factors and contributors.A better understanding of these risk factors and their mechanisms is an important first step to develop future research and prevention programs focusing on pediatric sleep problems.