Adaptive synchronization of chaotic Colpitts circuits against parameter mismatches and channel distortions

In this work, synchronization of chaotic Colpitts circuits, using adaptive controllers to combat circuit parameter mismatches and channel distortions, is studied by numerical simulations. Synchronization errors caused by different main circuit components are compared, and compensation for time-constant and time-varying circuit parameter mismatches is demonstrated. Different kinds of channel distortions, including time-constant and time-varying channel attenuation, Additive White Gaussian Noise (AWGN) are all investigated by numerical simulations and discussed. Simulation results indicated that the synchronization performance of chaotic Colpitts circuits can be greatly improved by applying adaptive controllers when parameter mismatches and channel attenuation are considered as time-constant or time-varying, but have no obvious enhancements regarding the effect on AWGN channel.     

Simple model for gas holdup and liquid velocity of annular photocatalytic external-loop airlift reactor under both bubble and developing slug flow

Based on the momentum conservation approach, a theoretical model was developed to predict the superficial liquid velocity, and a correlation equation was established to calculate the gas holdup of an annular external- loop airlift reactor(AELAR)in the bubble flow and developing slug flow pattern. Experiments were performed by using tap-water and silicone oil with the viscosity of 2.0 mm²/s(2cs-SiO)and 5.0 mm²/s(5cs-SiO)as liquid phases. The effects of liquid viscosity and flow pattern on the AELAR performance were investigated. The predictions of the proposed model were in good agreement with the experimental results of the AELAR. In addition, the comparison of the experimental results shows that the proposed model has good accuracy and could be used to predict the gas holdup and liquid velocity of an AELAR operating in bubble and developing flow pattern.     

Nobel Prize in Physics 2006

The discovery of the cosmic microwave background radiation in 1965 was a defining moment in the history of cosmology — the science that deals with the universe as a whole, its origin, evolution and future. This discovery was recognized with Nobel Prizes to Penzias and Wilson in 1978. The Nobel Prize in Physics for 2006 further acknowledged the importance of the study of this background radiation. The precise measurement of the spectrum of this radiation and its variation across the sky have helped our understanding of the evolution of structures in the universe. This article explains these discoveries and their importance. T Padmanabhan is a professor at IUCAA, Pune. He is interested in all aspects of theoretical physics, and especially in those in which gravity plays a role.     

Noise assisted directed motion at the molecular level — 2

The term noise is used to describe fluctuations about the mean deterministic stationary value of a physical quantity. It is now being increasingly realised that noise is an important ingredient to bring order in dynamical processes. Though it appears counterintuitive, noise seems to help in directing transport processes in biological systems at the molecular level. In Part 2 of the article, we discuss some more examples of noise assisted directed motion.     

The Journey Toward Transformational Learning in a Statewide Doctoral Program

This article describes strategies for redesigning the University of Missouri's Statewide Cooperative Ed.D. Cohort Program in educational leadership. Results had suggested a need to redesign aspects of the program in order to achieve higher levels of cognitive learning outcomes inclusive of transformational learning. To help meet this objective, the areas targeted for redesign were the curriculum as it relates to issues of diversity and ethics, instruction as it relates to group dynamics and cohort models, and increased time and a forum for students to reflect on their leadership practices. This forum also allowed faculty to monitor and assess the transformational learning outcomes of their students. This article is meant to assist others who are interested in fostering higher levels of transformational learning outcomes within their programs. Meredith L. Mountford holds a Bachelor of Science degree from Illinois State University, a Master of Science degree in educational administration from Northern Illinois University and a Philosophy of Science degree in educational administration from the University of Wisconsin—Madison. She is an Assistant Professor and has served as Director for the Statewide Cooperative Ed.D. Cohort Program in educational leadership at the University of Missouri—Columbia.     

Predictors of College Attendance Patterns of Rural Youth

This study investigated patterns of college attendance using data from a nationwide and contemporary sample of 2112 rural youth. We found that more than half of rural youth attended two-year institutions at some point during their college career and about a fourth initially enrolled in a two-year college before enrolling in a four-year college. Results also revealed that parental education, college preparatory track and preparation experiences, and teacher expectations predicted students’ college attendance patterns. Our findings point to the importance of two-year colleges and highlight the influence of family characteristics and students’ schooling experiences in the postsecondary trajectories of rural youth.     

Job Crafting and Identity in Low-Grade Work: How Hospital Porters Redefine the Value of their Work and Expertise

Over 25 years ago, Brown and Duguid (Organisation Science, 2(1), 40–57, 1991) highlighted the differences between the way organisations formally describe and delineate jobs and the actual practices of their employees. This paper combines ideas from their seminal contribution with theories of ‘job crafting’ and identity to examine the agentic behaviour of employees in low-grade, ‘dirty work’ as they utilise their expertise and practices to (re)frame their occupational identities and challenge their prescribed job boundaries. The evidence for the paper comes from a qualitative study of hospital porters in the UK’s National Health Service. It argues that this combined theoretical approach provides a potential research and employment framework to challenge the abstracted and stereotypical conceptions of the expertise related to low-grade jobs.     

Raising the bar on studying cultural evolution

Sasaki and Biro (2017, Nature Communications, 8, 15049) show that pairs of pigeons can increase the efficiency of their homing routes over several ‘generations’ in which pair members are gradually replaced by naïve birds. Their findings show that socially transmitted cumulative alterations of behavior are not unique to humans and suggest a way to examine potential mechanisms of cultural evolution.