Modeling the transient flow of undercooled glass-forming liquids

n a recent experimental study on flow behavior of Vitreloy-1 (Zr41.25Ti13.75Cu12.5Ni10Be22.5), three distinct modes of flow are suggested: Newtonian, non-Newtonian, and localized flow. In a subsequent study, the experimental flow data is utilized in a self-consistent manner to develop a rate equation to govern local free volume production. In the present study the production-rate equation is transformed into a transport equation that can be coupled with momentum and energy transport via viscosity to formulate a model capable to govern the flow of undercooled glass forming liquids. The model is implemented to study the flow behavior of undercooled Vitreloy-1 melt. For a temperature of 700 K and shear loading of 1.0 MPa, the model predicts that the flow profile gradually stabilizes to its Newtonian limit while the liquid is maintained in structural and thermal equilibrium. For the conditions of 675 K and 100 MPa, the model predicts that the flow profile departs from its Newtonian limit and gradually stabilizes to a non-Newtonian limit. The non-Newtonian profile is evaluated independently by considering structurally quasistatic conditions, which yield the shear-rate dependency of flow. For the conditions of 650 K and 2.0 GPa, the model predicts that the flow continuously localizes and ultimately accelerates unconstrained, while the system is driven out of structural and thermal equilibration towards an unstable state associated with free volume generation, viscosity degradation, and temperature rise. The computed temperature and shear rate evolutions for the three distinct flow modes are superimposed on a temperature-shear rate diagram and appear to computationally reproduce the experimental flow map. The system's structural state that appears to dictate flow behavior is quantified by a dimensionless number, which results from a time scale analysis of the free volume production equation

The half-second delay: what follows?

There is an increasing body of evidence that only a minuscule proportion of the sensory data processed by the unconscious mind (capable of processing approximately 11 million bits per second) is referred to the conscious mind (capable of processing approximately 50 bits per second). It is also clear that conscious awareness of stimuli from the environment lags actual perception by approximately half a second, but that a backward referral of subjective experience results in a individual?s perception of the stimulus and its conscious awareness as simultaneous. These findings challenge the primacy and supremacy of conscious processing of information on which a substantial proportion of educational practice and policy is based, and suggest a re-evaluation of the nature of teacher competence and expertise

Teachers developing assessment for learning: impact on student achievement

While it is generally acknowledged that increased use of formative assessment (or assessment for learning) leads to higher quality learning, it is often claimed that the pressure in schools to improve the results achieved by students in externally-set tests and examinations precludes its use. This paper reports on the achievement of secondary school students who worked in classrooms where teachers made time to develop formative assessment strategies. A total of 24 teachers (2 science and 2 mathematics teachers, in each of six schools in two LEAs) were supported over a six-month period in exploring and planning their approach to formative assessment, and then, beginning in September 1999, the teachers put these plans into action with selected classes. In order to compute effect sizes, a measure of prior attainment and at least one comparison group was established for each class (typically either an equivalent class taught in the previous year by the same teacher, or a parallel class taught by another teacher). The mean effect size was 0.32

Induced technological change with applications to modeling of climate-change policies

This grant supported research on induced innovation in the energy sector and the implications of induced innovation for climate change and climate-change policy. The first part of the research investigated the impact of energy prices on inventive activity focusing on the energy sector. The purpose was to improve our understanding of the determinants of inventive activity and to examine a number of hypotheses and specifications of the relationship. The second part incorporated the theoretical specifications and empirical results of the first part into the DICE integrated assessment models of climate change. This resulted in a revised model, known as the ''R&DICE model,'' and the major results are forthcoming in Grubler, Nakicenovic, and Nordhaus (GNN), ''Induced Technological Change and the Environment, Resources for the Future'', Washington, D.C., 2002, in a chapter entitled, ''Modeling Induced Innovation in Climate-Change Policy.'

The use of ICT in the assessment of modern languages: the English context and European viewpoints

The ever increasing explosion of highly attractive multimedia resources on offer has boosted the use of information and communication technology (ICT) in the teaching and learning of modern languages. The use of ICT to assess languages is less frequent, however, although online testing is starting to develop. This paper examines the national context for the assessment of modern foreign language proficiency in England, outlines the kinds of assessment currently available and the development of electronic forms of assessment and compares the above with the survey results of a European Union (EU) funded project on current good practice in online assessment of languages in other European countries. The findings indicate that speaking is inadequately served by online testing as tests currently focus primarily on receptive language skills. The implications for future successful online testing include the incorporation of interactive skills and effective formative feedback

Effect of Total Dissolved Solids and Sulfates in Drinking Water for Growing Steers

A study was conducted to determine the effects of implants and transportation on the metabolic status of feedlot steers. Steers (n = 28) were sorted by body weight, allocated into light or heavy blocks, and randomly assigned to one of two treatments. Treatments included non-implanted controls (CON) and steers implanted with Synovex Plus 70 d prior to harvest (IMP). Jugular blood and muscle biopsy samples (longissimus dorsi (LD) and semimembranosis (SM)) were collected 70 d post-implant, prior to transit. Steers were transported to Schuyler, NE, where blood and biopsy sampling was repeated. After harvest, carcass data were collected and muscle samples were taken from the LD, SM, Psoas Major (PM), and Illiacus (IL) muscles. Implanting increased (P \u3c 0.05) estradiol levels and improved live animal performance. Carcass weight and rib eye area were increased (P \u3c 0.05) in implanted steers. No dark cutters were found in either treatment. Pre-transit insulin/glucagon ratio and muscle glycogen levels did not differ (P \u3e 0.10) between treatments. Non-esterified fatty acid (NEFA) levels were reduced (P \u3c 0.05) in implanted steers pre-transit. Transit increased (P \u3c 0.05) NEFA levels, but had no effect (P \u3e 0.10) on insulin/glucagon ratio or muscle glycogen levels. Implanting did not affect (P \u3e 0.10) insulin/glucagon ratio, NEFA, or LD glycogen levels post-transit. Implanted steers had lower (P \u3c 0.05) glycogen levels in the SM than did non-implanted steers post-transit. Weight block affected (P \u3c 0.05) insulin and insulin/glucagon ratio levels, with steers in the light block having greater levels of each. Muscle pH and objective color (L*, a*, b*) of the LD were not biologically different between treatments. Implanted steers had greater (P \u3c 0.05) glycolytic potential values in the LD, and tended (P \u3c 0.10) to have higher L* values in the PM. Implanting increased (P \u3c 0.05) shear force of the LD. These data indicate that although implants affect bovine metabolism, other factors are necessary to cause a sufficient reduction in muscle glycogen and to produce a dark cutting carcass