Design of linear and nonlinear control systems via state variable feedback, with applications in nuclear reactor control

Linear and nonlinear control systems via state variable feedback with applications in nuclear reactor contro

Eulerian spectral closures for isotropic turbulence using a time-ordered fluctuation-dissipation relation

Procedures for time-ordering the covariance function, as given in a previous paper (K. Kiyani and W.D. McComb Phys. Rev. E 70, 066303 (2004)), are extended and used to show that the response function associated at second order with the Kraichnan-Wyld perturbation series can be determined by a local (in wavenumber) energy balance. These time-ordering procedures also allow the two-time formulation to be reduced to time-independent form by means of exponential approximations and it is verified that the response equation does not have an infra-red divergence at infinite Reynolds number. Lastly, single-time Markovianised closure equations (stated in the previous paper above) are derived and shown to be compatible with the Kolmogorov distribution without the need to introduce an ad hoc constant.Comment: 12 page

Statics, Dynamics and Manipulations of Bright Matter-Wave Solitons in Optical Lattices

Motivated by recent experimental achievement in the work with Bose-Einstein condensates (BECs), we consider bright matter-wave solitons, in the presence of a parabolic magnetic trap and a spatially periodic optical lattice (OL), in the attractive BEC. We examine pinned states of the soliton and their stability by means of perturbation theory. The analytical predictions are found to be in good agreement with numerical simulations. We then explore possibilities to use a time-modulated OL as a means of stopping and trapping a moving soliton, and of transferring an initially stationary soliton to a prescribed position by a moving OL. We also study the emission of radiation from the soliton moving across the combined magnetic trap and OL. We find that the soliton moves freely (without radiation) across a weak lattice, but suffers strong loss for stronger OLs.Comment: 7 pages, 5 figs, Phys Rev A in Press (2005

Self Consistent Expansion for the Molecular Beam Epitaxy Equation

Motivated by a controversy over the correct results derived from the dynamic renormalization group (DRG) analysis of the non linear molecular beam epitaxy (MBE) equation, a self-consistent expansion (SCE) for the non linear MBE theory is considered. The scaling exponents are obtained for spatially correlated noise of the general form $D({\vec r - \vec r',t - t'}) = 2D_0 | {\vec r - \vec r'} |^{2\rho - d} \delta ({t - t'})$. I find a lower critical dimension $d_c (\rho) = 4 + 2\rho$, above, which the linear MBE solution appears. Below the lower critical dimension a r-dependent strong-coupling solution is found. These results help to resolve the controversy over the correct exponents that describe non linear MBE, using a reliable method that proved itself in the past by predicting reasonable results for the Kardar-Parisi-Zhang (KPZ) system, where DRG failed to do so.Comment: 16 page

A discourse analysis of trainee teacher identity in online discussion forums

Teacher education involves an identity transformation for trainees from being a student to being a teacher. This discourse analysis examined the online discussion board communications of a cohort of trainee teachers to better understand the situated identities of the trainees and how they were presented online. Their discussion board posts were the primary method of communication during placement periods and, as such, provided insight into how the trainees situated their identities in terms of being a student or being a teacher. During the analysis, the community boundaries, language and culture were explored along with the tutor's power and role in the identity transformation process. This involved looking at the lexis used by the students, the use of pronouns to refer to themselves and others such as teachers and pupils, the types of messages allowed in the community and the effect of the tutor's messages on their communication. The research found that the trainees felt comfortable with teaching but did not feel like teachers during the course. Tutors and school teachers need to develop an awareness of the dual nature of trainees' identities and help promote the transition from student to teacher. In the beginning of the course, trainees should be familiarised with teacher vocabulary and practical concepts in addition to pedagogical theory. Towards the end of the course, trainee identity as teachers could be promoted through the use of authentic assessments that mirror real teacher tasks and requirements

Ethanol and Anaerobic Conditions Reversibly Inhibit Commercial Cellulase Activity in Thermophilic Simultaneous Saccharification and Fermentation (tSSF)

A previously developed mathematical model of low solids thermophilic simultaneous saccharification and fermentation (tSSF) with Avicel was unable to predict performance at high solids using a commercial cellulase preparation (Spezyme CP) and the high ethanol yield Thermoanaerobacterium saccharolyticum strain ALK2. The observed hydrolysis proceeded more slowly than predicted at solids concentrations greater than 50 g/L Avicel. Factors responsible for this inaccuracy were investigated in this study

Effect of Rye-Ryegrass Stocking Rate, Breed Types, and Sex of Calf on Feedlot Performance

Last updated: 6/12/200

Declining drinking among adolescents: are we seeing a denormalisation of drinking and a normalisation of non-drinking?

Background In the early 2000s, alcohol use among young people began to decline in many western countries, especially among adolescents (aged between 12-17 years old). These declines have continued steadily over the past two decades, against the backdrop of much smaller declines among the general population. Argument Hypotheses examining individual factors fail adequately to provide the necessary ‘big picture’ thinking needed to understand declines in adolescent drinking. We use the normalisation thesis to argue that there is strong international evidence for both processes of denormalisation of drinking and normalisation of non-drinking occurring for adolescents in many western countries. Conclusions Research on declining adolescent drinking provides evidence of both denormalisation of alcohol consumption and normalisation of non-drinking. This has implications for enabling policy environments more amenable to regulation and increasing the acceptability of non-drinking in social contexts. Normalisation theory (and its various interpretations) provides a useful multi-dimensional tool for understanding declines in adolescent drinking

Response to commentaries: (de)normalization of drinking and its implications for young people, sociality, culture and epidemiology

Commentar

Examining trends in the representation of young people and alcohol in Australian newspapers over twenty years (2000-2019)

Background: The news media can reflect and influence public opinion, as well as affect individual practice. In the context of significant changes in alcohol consumption among young people over the past twenty years, we examined Australian newspaper reporting of young people (under 18 years) and alcohol to assess whether there have been changes over time in the content and slant of articles that reflect or elucidate these trends. Methods: Factiva was used to search newspaper articles from major Australian newspapers over a twenty year period (2000-2019). After screening, two researchers coded 2,415 newspaper articles across four key domains: article type, article theme, sources cited and topic slant (e.g. approving, disapproving tone). Change over time across the study period was assessed using joinpoint Poisson regression analyses. Results: There was a significant increase in articles on young people and alcohol between 2000 and 2008, before a corresponding decrease to 2019. Policy or prevention strategies were the most common theme of articles (35.8%), followed by articles reporting on risks or harms associated with alcohol use for young people (18.1%). Researchers were the most common source reported (25.1%), followed by politicians (19.0%). Three quarters of articles (75.9%) had a socially disapproving topic slant, which increased significantly up until 2011, with a corresponding decrease thereafter. Conclusion: Attention to, and problematisation of, young people and alcohol increased in the first decade of this millennium which may have acted to sustain or accelerate declining drinking trends. However, this dissipated back to baseline levels in the second decade, which may indicate a lag time in recognition of young people’s drinking becoming less of a public health ‘problem’