A Direct Test for Cointegration Between a Pair of Time Series

In this paper we introduce a new test of the null hypothesis of no cointegration between a pair of time series. For a very simple generating model, our test compares favourably with the Engle–Granger/Dickey–Fuller test and the Johansen trace test. Indeed, shortcomings of the former motivated the development of our test. The applicability of our test is extended to series generated by low-order vector autoregressions. Again, we find evidence that this general version of our test is more powerful than the Johansen test. The paper concludes with an empirical example in which the new test finds strong evidence of cointegration, but the Johansen test does not.     

ESCHERICHIA COLI O157 IN IRISH FEEDLOT CATTLE: A LONGITUDINAL STUDY INVOLVING PREHARVEST AND HARVEST PHASES OF THE FOOD CHAIN

The aim of this study was to investigate fecal shedding and transmission of E. coli O157 in cohorts of cattle within a feedlot, to assess subsequent contamination of carcasses with this pathogen and to identify risk factors associated with fecal shedding of E. coli O157. A cohort of 133 heifers housed infour adjacent pens was examined over a five month period, from entering the feedlot to slaughter. Individual rectal fecal samples and pen environmental samples were taken at monthly intervals. The entire outer and inner surfaces of a carcass side of each animal were swabbed immediately following slaughter.
E. coli O157 was isolated from 136 (23%) of the 600 rectal fecal samples; 96% of which contained virulent markers. One hundred and sixty environmental samples were examined and E. coli O157 was isolated from 46 (29%), all of which contained virulent markers. E. coli O157 was not isolated from any of the dressed carcasses. The prevalence of E. coli O157 fecal shedding may be related to the pen and E. coli O157 contamination of the pen floor feces, water trough and feed.
E. coli O157 should be considered as a pathogen shed in the feces of a substantial proportion of feedlot cattle. However, with good hygienic practice at harvest, a very low level of this pathogen can be achieved on dressed carcasses.     

PASTING CHARACTERISTICS OF RICE FLOUR-BASED BATTER COMPARED TO WHEAT FLOUR-BASED BATTER

Rice flour‐based batter (RFBB) formulations were developed for deep fat fried chickendrumstick application. The effects of ingredients on pasting characteristics of RFBB and wheat flour based‐batter (WFBB) were compared using the Rapid Visco‐Analyzer (RVA). Pasting properties were influenced significantly by ratios of rice to corn flour, oxidized corn starch, and methylcellulose. The peak viscosity, breakdown, and setback increased significantly as rice flour level increased, whereas increasing levels of oxidized corn starchyielded opposite results. Pasting characteristics of RFBB were significantly different from those of WFBB.     

Use of Mechanically Separated Spleen in Frankfurters

Beef and pork frankfurters were produced with 0, 5, 10, and 15% of the meat block being mechanically separated spleen (MSS). No fatting or peelability problems were experienced. Frankfurters were held at 2°C and evaluated at 2-wk intervals for 6 wk. Consumer panelists rated all products acceptable. A bi-monthly laboratory taste panel evaluated all frank furters (except the 15% product) acceptable during storage. Allo-Kramer shear values decreased with increased MSS, Frankfurters with 5, 10, and 15% MSS had 2.2, 3.9, and 4.9 times more iron than the control, respectively. Level of MSS did not influence bacterial numbers.     

Taking up the situated cognition challenge with ripple down rules

Situated cognition poses a challenge that requires a paradigm shift in the way we build symbolic knowledge-based systems. Current approaches require complex analysis and modelling and the intervention of a knowledge engineer. They rely on building knowledge-level models which often result in static models that suffer from the frame of reference problem. This approach has also resulted in an emphasis on knowledge elicitation rather than user requirements elicitation. The situated nature of knowledge necessitates a review of how we build, maintain and validate knowledge-based systems. We need systems that are flexible, intuitive and that interact directly with the end-user. We need systems that are designed with maintenance in mind, allowing incremental change and on-line validation. This will require a technique that captures knowledge in context and assists the user to distinguish between contexts. We take up this challenge with a knowledge acquisition and representation method known as Ripple-down Rules. Context in Ripple-down Rules is handled by its exception structure and the storing of the case that prompted a rule to be added. A rule is added as a refinement to an incorrect rule by assigning the correct conclusion and picking the salient features in the case that differentiate the current case from the case associated with the wrong conclusion. Thus, knowledge acquisition and maintenance are simple tasks, designed to be performed incrementally while the system is in use. Knowledge acquisition, maintenance and inferencing are offered in modes that can be performed reflexively without a knowledge engineer. We further describe the addition of modelling tools to assist the user to reflect on their knowledge for such purposes as critiquing, explanation, “what-if” analysis and tutoring. Our aim is to provide a system that lets the user choose the mode of interaction and view of the knowledge according to the situation in which they find themselves and their own personal preferences.     

Use of near infrared spectroscopy to evaluate the intensity of extrusion-cooking processing of pea flour

Twenty-five different pea extrudates were produced using a Clextral BC45 twinscrew extruder. Near infrared reflectance (NIR) spectra of the extrudates were recorded between 1100 and 2500 nm. the application of principal component analysis (PCA) on these spectral data permitted discrimination between the extrudates produced under moderate, intermediate or severe conditions of extrusion-cooking. the study of protein quality through solubility experiments, polyacrylamide gel electrophoresis, determination of available basic amino acids and brown colour measurement showed that, under moderate conditions of extrusion-cooking, protein was only slightly affected. All protein subunits could be restored after solubilization in phosphate buffer containing a detergent and a reducer of disulphide bonds. However, under severe conditions of extrusion-cooking, the extrudates exhibited a relatively intense brown colour and all protein fractions were implicated in non-disulphide covalent bonds and underwent some macromolecular degradation. Therefore, the spectral discrimination between pea extrudates which was related to the processing parameters, could also be related to the degree of transformation of these extrudates. Thus, the method may be used to classify an extrudate produced under unknown conditions by projecting its spectrum on the similarity maps obtained by PCA on a known collection of extrudates.