Upfront: Economic news across the region

Articles: "Danville works: new IKEA factory hums;" "Troubled asset relief: Bank of America repays government loans;" "Apples, soybeans, poultry: Virginia's exports to Cuba grow;" "Cash economy: underground commerce grows in recession"Economic conditions ; Federal Reserve District, 5th

Bubbly Turbulent Drag Reduction Is a Boundary Layer Effect

In turbulent Taylor-Couette flow, the injection of bubbles reduces the overall drag. On the other hand, rough walls enhance the overall drag. In this work, we inject bubbles into turbulent Taylor-Couette flow with rough walls (with a Reynolds number up to 4×105), finding an enhancement of the dimensionless drag as compared to the case without bubbles. The dimensional drag is unchanged. As in the rough-wall case no smooth boundary layers can develop, the results demonstrate that bubbly drag reduction is a pure boundary layer effec

Modelling of trends in Twitter using retweet graph dynamics

In this paper we model user behaviour in Twitter to capture the emergence of trending topics. For this purpose, we first extensively analyse tweet datasets of several different events. In particular, for these datasets, we construct and investigate the retweet graphs. We find that the retweet graph for a trending topic has a relatively dense largest connected component (LCC). Next, based on the insights obtained from the analyses of the datasets, we design a mathematical model that describes the evolution of a retweet graph by three main parameters. We then quantify, analytically and by simulation, the influence of the model parameters on the basic characteristics of the retweet graph, such as the density of edges and the size and density of the LCC. Finally, we put the model in practice, estimate its parameters and compare the resulting behavior of the model to our datasets.Comment: 16 pages, 5 figures, presented at WAW 201

Optimal Control for Wind Turbine Wake Mixing on Floating Platforms

Dynamic induction control is a wind farm flow control strategy that utilises wind turbine thrust variations to accelerate breakdown of the aerodynamic wake and improve downstream turbine performance. However, when floating wind turbines are considered, additional dynamics and challenges appear that make optimal control difficult. In this work, we propose an adjoint optimisation framework for non-linear economic model-predictive control, which utilises a novel coupling of an existing aerodynamic wake model to floating platform hydrodynamics. Analysis of the frequency response for the coupled model shows that it is possible to achieve wind turbine thrust variations without inducing large motion of the rotor. Using economic model-predictive control, we find dynamic induction results that lead to an improvement of 7% over static induction control, where the dynamic controller stimulates wake breakdown with only small variations in rotor displacement. This novel model formulation provides a starting point for the adaptation of dynamic wind farm flow control strategies for floating wind turbines.Comment: 6 pages, 8 figures, accepted for publication for IFAC World Congress 202

Estimating economic and social welfare impacts of pension reform

This paper examines the impact of two effects of the pension reform package that the UK Government put forward in the May White Paper Security in retirement: the likely increase in the number of older people working due to a higher State Pension age and the likely rise in saving due to more people putting away money for retirement. The overall effect of changes to State Pension age and the introduction of personal accounts on UK incomes is likely to be in the range of 0.9 – 3.1 per cent. Although these numbers are relatively small proportions of the total economy, they represent significant sums. In terms of today’s economy, they would be worth around £11 – 38 billion. This paper also applies an innovative economic analysis to examine the scale of the increase in people’s wellbeing as a result of improved consumption smoothing. It finds that if people save for retirement through personal accounts, then generally their wellbeing will be enhanced.pension reform; consumption smoothing; social welfare

Die ontwikkelikng van 'n meetinstrument om die transiente van roterende masjiene te meet

ThesisTransducers are needed to detect defects in rotational machines . If a potential defect is detected in time , without dismantling the machine , repairs could be carried out when the maintenance facilities are available with minimum loss in production . Analysis of the speed and acceleration parameters are used to predict the existence of defects in a machine . This project in volved the development and utilisation of a comprehensive set of software in conjunction with a high resolution measuring instrument , which have the ability to measure both the speed and acceleration parameters of rotational machines . The measuring instrument hardware consists of the following : • Shaft encoder : A high resolution incremental shaft encoder is used to determine the tor_g..u e of the rotat-ing shaft . The output pulse of the shaft encoder is processed within the encoder to minimise the generation of noise . • Signal proces;.. ing unit : The speed of the machine is obtained from the signal processing unit with the aid of analogue techniques , by converting the output pulses of the shaft encoder to a corresponding voltage . By differentiation of the speed signal , the instantaneous acceleration of the machine is obtained . The output of the instrument is digitized by an analogue-to-digital converter card before the signal is processed by a computer. The software developed for the measuring instrument displays a menu, showing the options to be carried out to ensure the correct sampling of the speed and acceleration of the motor . The sampled data is shown graphically on the computer screen before it is saved for processing . Correct operation of the measuring instrument has been verified by practical evaluation . A number of tests in this regard have been carried out and satisfactory results were achieved. Particular knowledge regarding the following has been obtained: • Transient characteristics of rotational machines . • Format, construction and use of transducers

Breaks in the 45S rDNA Lead to Recombination-Mediated Loss of Repeats

rDNA repeats constitute the most heavily transcribed region in the human genome. Tumors frequently display elevated levels of recombination in rDNA, indicating that the repeats are a liability to the genomic integrity of a cell. However, little is known about how cells deal with DNA double-stranded breaks in rDNA. Using selective endonucleases, we show that human cells are highly sensitive to breaks in 45S but not the 5S rDNA repeats. We find that homologous recombination inhibits repair of breaks in 45S rDNA, and this results in repeat loss. We identify the structural maintenance of chromosomes protein 5 (SMC5) as contributing to recombination-mediated repair of rDNA breaks. Together, our data demonstrate that SMC5-mediated recombination can lead to error-prone repair of 45S rDNA repeats, resulting in their loss and thereby reducing cellular viability

Wake up and smell the bloody Eucalyptus!! Using pluralistic pedagogical approaches to decolonise curricula and advance botanical awareness in first-year undergraduate biology

The weaving of Aboriginal and/or Torres Strait Islander knowledges into higher education curricula is a priority of Universities Australia and remains an ethical obligation for all educators to right the wrongs of the past and make noise to fill the ‘Great Australian Silence’ (W.E.H. Stanner’s 1968 Boyer Lectures). To do so in a culturally respectful way necessitates both co-design and decolonisation of oppressive/restrictive western scientific frameworks. Alternative ways of acquiring and holding knowledge do exist! Similarly, as Biology educators, we must address the ‘Botanical silence’ in Science curricula, where animals are generally prioritised at the expense of plants. This is a symptom of Plant Blindness - a term coined to encapsulate the tendency to ignore plants in our everyday lives (Wandersee & Shussler, 1999). As educators, we have a duty to address this organismal bias. In response, we have conceived a new Practical, ‘Bulu – shadow of a tree’, whose content sits in the shadows cast by the behemoth of western science (e.g., Indigenous knowledges, plants, sensorial experiences, Indigenous Cultural and Intellectual Property (ICIP)). We highlight the constraints of western knowledge acquisition by exploring subjective, botanical, sensory experiences (smell, touch, and taste) that create deep, personalized, place-based memories for students, spawning familiarity and belonging. This outdoors Practical class requires deep observation of plant morphology as we expose the hidden beauty of plants - leaf aromas. We use native plant species, focusing on Eucalyptus spp., to instigate a series of self-reflections to explore the role of subjectivity in Science (Botany) and intellectual property of researchers and their discoveries. Can we objectively describe smells as a means of sharing knowledge? If not, should we abandon our senses and limit our own knowledge acquisition to methodologies sanctioned by colonialist frameworks; frameworks historically used to control First Nations knowledge? Who benefits from the Eucalyptus industry? We will detail how we have employed olfactory pedagogies to enhance place-based learning methodologies thereby initiating conversations, creating campus belonging and stimulating critical reflections on a range of ethical, methodological, and legal (ICIP) aspects of native plants, their products, and derived industries. REFERENCE Wandersee, J., & Schussler, E. (1999). Preventing Plant Blindness. The American Biology Teacher, 61, 82-86. https://doi.org/10.2307/4450624

Confidence Is the Bridge between Multi-stage Decisions

Demanding tasks often require a series of decisions to reach a goal. Recent progress in perceptual decision-making has served to unite decision accuracy, speed, and confidence in a common framework of bounded evidence accumulation, furnishing a platform for the study of such multi-stage decisions. In many instances, the strategy applied to each decision, such as the speed-accuracy trade-off, ought to depend on the accuracy of the previous decisions. However, as the accuracy of each decision is often unknown to the decision maker, we hypothesized that subjects may carry forward a level of confidence in previous decisions to affect subsequent decisions. Subjects made two perceptual decisions sequentially and were rewarded only if they made both correctly. The speed and accuracy of individual decisions were explained by noisy evidence accumulation to a terminating bound. We found that subjects adjusted their speed-accuracy setting by elevating the termination bound on the second decision in proportion to their confidence in the first. The findings reveal a novel role for confidence and a degree of flexibility, hitherto unknown, in the brain's ability to rapidly and precisely modify the mechanisms that control the termination of a decision.We thank the Wellcome Trust, the Human Frontier Science Program, the Royal Society (Noreen Murray Professorship in Neurobiology to D.M.W.), Howard Hughes Medical Institute, National Eye Institute grant EY11378 to M.N.S., a Sloan Research Fellowship to R.K., and Simons Collaboration on the Global Brain grant 323439 to R.K