Adapting the International System of Units to the twenty-first century

We review the proposal of the International Committee for Weights and Measures (Comité International des Poids et Mesures, CIPM), currently being considered by the General Conference on Weights and Measures (Conférences Générales des Poids et Mesures, CGPM), to revise the International System of Units (Le Système International d’Unitès, SI). The proposal includes new definitions for four of the seven base units of the SI, and a new form of words to present the definitions of all the units. The objective of the proposed changes is to adopt definitions referenced to constants of nature, taken in the widest sense, so that the definitions may be based on what are believed to be true invariants. In particular, whereas in the current SI the kilogram, ampere, kelvin and mole are linked to exact numerical values of the mass of the international prototype of the kilogram, the magnetic constant (permeability of vacuum), the triple-point temperature of water and the molar mass of carbon-12, respectively, in the new SI these units are linked to exact numerical values of the Planck constant, the elementary charge, the Boltzmann constant and the Avogadro constant, respectively. The new wording used expresses the definitions in a simple and unambiguous manner without the need for the distinction between base and derived units. The importance of relations among the fundamental constants to the definitions, and the importance of establishing a mise en pratique for the realization of each definition, are also discussed

The economic cost of weeds in dryland cotton production systems of Australia

Economic losses and costs associated with weeds in dryland cotton production are important, both for growers and for industry bodies when making decisions about research priorities and research and development funding. A survey was conducted to provide information on weed types, control strategies and estimated costs to growers. We used information from the survey to estimate conventional financial losses due to weeds, and as a basis for evaluating aggregate economic (society) impacts. An economic surplus model was used to estimate the aggregate societal impact of weeds for three production regions in north-eastern Australia. The annual economic costs associated with weeds were estimated to be $41 million, and the on-farm financial costs were$25 million. While these are past (sunk) costs, and based on a total removal of weeds, the approach outlined here can be used to begin evaluating likely future returns from technologies or management improvements for different agricultural problems.Weeds, Dryland Cotton, and Economics, Crop Production/Industries, Environmental Economics and Policy,

Dose–response effect of a whey protein preload on within-day energy intake in lean subjects

The effect of consuming different amounts of whey protein on appetite and energy intake was investigated in two separate studies using randomised, crossover designs. Healthy-weight men and women (range: BMI 19·0–25·0 kg/m2, age 19·4–40·4 years) consumed one of four 400 ml liquid preloads, followed by an ad libitum test meal 90 min later. In study 1, preloads were 1675 kJ with 12·5, 25 or 50 % of energy from protein, and in study 2, preloads were 1047 kJ with 10, 20 or 40 % energy from protein. Flavoured water was used as the control in both the studies. Appetite ratings were collected immediately before 30, 60 and 90 min after consuming the preloads; and immediately, 30 and 60 min after consuming the test meal. In study 1, energy intake following the control preload (4136 (sem 337) kJ) was significantly higher than each of the 12·5 % (3520 (sem 296) kJ), 25 % (3384 (sem 265) kJ) and 50 % (2853 (sem 244) kJ) protein preloads (P < 0·05). Intake after the 12·5 % preload was significantly higher than following 25 and 50 % preloads (P < 0·05). In study 2, energy intake following the control preload (4801 (sem 325) kJ) was higher than following the 10 % (4205 (sem 310) kJ), 20 % (3988 (sem 250) kJ) and 40 % (3801 (sem 245) kJ) protein preloads (P < 0·05). There were no differences in subjective appetite ratings between preloads in either study. These findings indicate a dose–response effect of protein content of the preload on energy intake at a subsequent meal

Large-Scale Fermentation of E. Coli for the Production of High-Purity Isoprene

We present a process for the production of isoprene via the fermentation of glucose. Based on our current specifications, we conclude that the use of recombinant E.coli for the fermentation of glucose is a novel yet unprofitable venture. Our current design entails the continuous production of isoprene using 3 pre-seed, 3 seed, and 5 production fermenters each with a production fermentation time of 72 hours. Our scheduling of the fermenters allowed us to produce isoprene continuously at a steady rate, and the liquid by-products of the fermentation were removed and sterilized at the end of each batch. Isoprene was mainly present in the vapor phase during the fermentation and was purified using a combination of an absorption using ISOPAR v, stripping with steam, and separation using a flash vessel. It was desired that the fermentation was operated near the minimum oxygen concentration (MOC) as such conditions allowed for the highest production rate of isoprene based on the preliminary studies done by Chotani in their patent. The fermentation was operated at 34 °C and 1.7 bar with glucose and oxygen as the reactants producing isoprene, carbon dioxide, and water as the products. The results of our design suggest that the price of isoprene is too low when compared to the costs of raw materials, making this process economically unfeasible under present market conditions. We project that $4.08 worth of glucose will be need for each pound of isoprene which currently goes for$0.79/lb. Additionally, the metabolic pathway of isoprene is highly exothermic, requiring large utility requirements in terms of chilled water to remove heat from the fermenters. We are unsure of impacts of rapidly changing the temperature of E.Coli on production as there is no data regarding the robustness of the strain. Overall, the fixed capitals costs incurred make this process even more unappealing for further consideration

Study of bluff body flow fields and aeroelastic stability using a discrete vortex method

A two dimensional discrete vortex method has been developed to simulate the unsteady, incompressible flow field and aerodynamic loading on bluff bodies. The method has been validated successfully on a range of simple bluff geometries, both stoic and oscillating, and has also been validated on a wider range of problems including static and oscillating suspension bridge deck sections. The results have been compared with experimental data and demonstrate good qualitative and quantitative agreement, and also compare favourably with other computational methods. Most notably, the method has been used to study the aeroelastic stability of a recent bridge deck, with accurate predictions of the critical flutter velocity. The basis of the method is the discretisation of the vorticity field into a series of vortex particles, which are transported in the flow field that they collectively induce. In the method presented herein, the time evolution of the system of particles is calculated by solving the vorticity transport equation in two stages: employing the Biot-Savart law to calculate particle velocities and random walks to simulate flow diffusion. The Lagrangian approach to the calculation avoids the necessity for a calculation grid, and therefore removes some of the problems associated with more traditional grid based methods. These include numerical diffusion and difficulties in resolving small scale vortical structures. In contrast, vortex methods concentrate particles in areas of vorticity, and can provide high quality representations of these small scale structures. Dispensing with a calculation mesh also eases the task of modelling a more arbitrary range of geometries. In particular, vortex methods are well suited to the analysis of moving body problems. Results of the validation exercise are firstly presented for a range of simple bluff geometries to give confidence in the results before moving on to more complex geometries. These results include the effect of incidence on the aerodynamic loading for a stationary square cylinder, and also a study of the effect on aspect ratio for rectangular cylinders. This includes the limiting case of a flat plate. Vortex lock-in is studied on a square cylinder undergoing a forced transverse oscillation, for a range of frequencies and amplitudes. The results in each of these cases are in good agreement with experimental data

Why Do Pro Forma and Street Earnings not Reflect Changes in GAAP? Evidence From SFAS 123R

This study examines how key market participants—managers and analysts—responded to SFAS 123R’s controversial requirement that firms recognize stock-based compensation expense. Despite mandated recognition of the expense, some firms’ managers exclude it from pro forma earnings and some firms’ analysts exclude it from Street earnings. We find evidence consistent with managers opportunistically excluding the expense to increase earnings, smooth earnings, and meet earnings benchmarks but no evidence that these exclusions result in an earnings measure that better predicts future firm performance. In contrast, we find that analysts exclude the expense from earnings forecasts when exclusion increases earnings’ predictive ability for future performance and that opportunism generally does not explain exclusion by analysts incremental to exclusion by managers. Thus our findings indicate that opportunism is the primary explanation for exclusion of the expense from pro forma earnings and predictive ability is the primary explanation for exclusion from Street earnings. Our findings suggest the controversy surrounding the recognition of stock-based compensation expense may be attributable to cross-sectional variation in the relevance of the expense for equity valuation, as well as to differing incentives of market participants