Subgroups of direct products of two limit groups

If S is a subgroup of a direct product of two limit groups, and S is of type FP(2) over the rationals, then S has a subgroup of finite index that is a direct product of at most two limit groups.Comment: 18 pages, no figure

Subgroups of direct products of elementarily free groups

We exploit Zlil Sela's description of the structure of groups having the same elementary theory as free groups: they and their finitely generated subgroups form a prescribed subclass E of the hyperbolic limit groups. We prove that if $G_1,...,G_n$ are in E then a subgroup $\Gamma\subset G_1\times...\times G_n$ is of type \FP_n if and only if $\Gamma$ is itself, up to finite index, the direct product of at most $n$ groups from $\mathcal E$. This answers a question of Sela.Comment: 19 pages, no figure

Normalisers in Limit Groups

Let \G be a limit group, S\subset\G a subgroup, and $N$ the normaliser of $S$. If $H_1(S,\mathbb Q)$ has finite \Q-dimension, then $S$ is finitely generated and either $N/S$ is finite or $N$ is abelian. This result has applications to the study of subdirect products of limit groups.Comment: 10 pages, no figure

The rationality and reliability of expectations reported by British households: micro evidence from the British household panel survey

This paper assesses the accuracy of individuals' expectations of their financial circumstances, as reported in the British Household Panel Survey, as predictors of outcomes and identifies what factors influence their reliability. As the data are qualitative bivariate ordered probit models, appropriately identified, are estimated to draw out the differential effect of information on expectations and realisations. Rationality is then tested and we seek to explain deviations of realisations from expectations at a micro-economic level, possibly with reference to macroeconomic shocks. A bivariate regime-switching ordered probit model, distinguishing between states of rationality and irrationality, is then estimated to identify whether individual characteristics affect the probability of an individual using some alternative model to rationality to form their expectations. --household behaviour,expectation formation

A METHOD FOR DETERMINING RANCH PROFIT PROBABILITIES WHEN LIVESTOCK YIELDS ARE NORMALLY DISTRIBUTED

Data on net turnoff for small, medium-sized and large cow-calf and small and large size yearling ranches were tested for normality using the Shapiro - Wilk test. The yield data examined were accepted as normally distributed at the alpha = .10 level. The probability of profit for each type of ranch was assessed using normal curve techniques for nine different cost-price alternatives and weather conditions. Yearling cattle ranchers had higher profit probabilities than cow-calf ranchers. Prices received had more influence on profit probabilities than weather conditions.Livestock Production/Industries,

The challenge of integrating non-continuous processes-milk powder plant case study

The integration of non-continuous processes such as a milk powder plant present a challenge for existing process integration techniques. Current techniques are generally based on steady and continuous operation which for some industries is not the case. Milk production varies considerably during the year as dairy cows in New Zealand are grazed on pasture, which affects the scheduling and operation of plants on site. The frequency and duration of cleaning cycles and non-productive operating states can have a major affect on energy demand and the availability of heat sources and heat sinks. In this paper the potential for indirect heat transfer between the several plants using a heat recovery loop and stratified tank at a typical New Zealand dairy factory is investigated. The maximum amount of heat recovery is calculated for a range of recirculation loop temperatures. The maximum amount of heat recovery can be increased considerably if the temperature of the hot fluid in the recirculation loop is varied depending on which condition the site is operating under

Designing and managing multiple pipelines

There is now a growing recognition that supply chains should be designed from ‘the customer backwards’ rather than from ‘the company outwards’. If such a view is accepted then the implication is that since the organisation will likely be serving multiple markets or segments there will be the need to design and manage multiple ‘pipelines’ to serve those different customers. To assist decision makers in their choice of appropriate supply chain design a framework is proposed based upon multiple criteria. A case study is presented which highlights the benefits of selecting, engineering and operating multiple pipelines tailored to the needs of th

Integrating heat recovery from milk powder spray dryer exhausts in the dairy industry

Heat recovery from milk powder spray dryer exhausts has proven challenging due to both economic and thermodynamic constraints. Integrating the dryer with the rest of the process (e.g. evaporation stages) can increase the viability of exhaust recovery. Several potential integration schemes for a milk powder plant have been investigated. Indirect heat transfer via a coupled loop between the spray dryer exhaust and various heat sinks were modeled and the practical heat recovery potential determined. Hot utility use was reduced by as much as 21% if suitable heat sinks are selected. Due to high particle loading and operating temperatures in the particle sticky regime, powder deposition in the exhaust heat exchanger is perhaps the greatest obstacle for implementing heat recovery schemes on spray dryers. Adequate cleaning systems are needed to ensure continuous dyer operation

Efficient Aggregation of Panel Qualitative Survey Data

Qualitative business survey data are used widely to provide indicators of economic activity ahead of the publication of official data. Traditional indicators exploit only aggregate survey information, namely the proportions of respondents who report “up” and “down”. This paper examines disaggregate or firm-level survey responses. It considers how the responses of the individual firms should be quantified and combined if the aim is to produce an early indication of official output data. Having linked firms’ categorical responses to official data using ordered discrete choice models, the paper proposes a statistically efficient means of combining the disparate estimates of aggregate output growth which can be constructed from the responses of individual firms. An application to firm-level survey data from the Confederation of British Industry shows that the proposed indicator can provide early estimates of output growth more accurately than traditional indicators.Survey Data; Indicators; Quantification; Forecasting; Forecast Combination