A simulation approach to assess the minimal number of real-time PCR replicates for GM quantification

The quantification of genetically modified (GM) ingredients in food and feed typically uses real-time quantitative PCR (RT-QPCR). In recent years a multitude of new RT-QPCR assays have facilitated increased method performance. The level of sample replication within these assays is a fundamental aspect that needs to be considered to produce results with high confidence. In this paper we describe the use of a modelling approach as applied to GM and RT-QPCR data sets, to objectively assesses the effect of different levels of PCR replication in terms of the variability associated with a result, and demonstrate that it is possible to use a reduced level of replication without a subsequent reduction in the confidence of a result. Using an example data set, we show it is possible to reduce the sample level of replication from six to three PCR replicates, without a significant change in the mean value of the result. The use of such an approach can facilitate the use of the minimum number of replicates in order to produce an accurate result, thus saving on important resources involved in quantification assays.     

Feature Selection vs Theory Reformulation: A Study of Genetic Refinement of Knowledge-based Neural Networks

Expert classification systems have proven themselves effective decision makers for many types of problems. However, the accuracy of such systems is often highly dependent upon the accuracy of a human expert's domain theory. When human experts learn or create a set of rules, they are subject to a number of hindrances. Most significantly experts are, to a greater or lesser extent, restricted by the tradition of scholarship which has preceded them and by an inability to examine large amounts of data in a rigorous fashion without the effects of boredom or frustration. As a result, human theories are often erroneous or incomplete. To escape this dependency, machine learning systems have been developed to automatically refine and correct an expert's domain theory. When theory revision systems are applied to expert theories, they often concentrate on the reformulation of the knowledge provided rather than on the reformulation or selection of input features. The general assumption seems to be that the expert has already selected the set of features that will be most useful for the given task. That set may, however, be suboptimal. This paper studies theory refinement and the relative benefits of applying feature selection versus more extensive theory reformulation.     

Predicting sales performance, job satisfaction, and depression by using the Achievement Strivings and Impatience-Irritability dimensions of Type A behavior.

Recent research suggested that two dimensions of Type A behavior, namely, Achievement Strivings (AS) and Impatience-Irritability (II), differentially predict physical health and performance outcomes. The present study extends this research and examines whether AS and II differentially predict work performance (number of insurance policies sold), work attitudes (job satisfaction), and depression in a sample of 117 life insurance salespersons. As hypothesized, after statistically controlling for relevant biographical variables and II, AS predicted the number of policies sold and job satisfaction but was not related to depression. After partialing out the effect of relevant biographical variables and AS, II was associated with depression but not with the number of policies sold. In addition, controlling for the same variables, II was negatively associated with job satisfaction. Implications for the prediction of sales performance, job satisfaction, and depression, and interventions designed to decrease the negative consequences of Type A by reducing II but not AS, are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Loss mechanisms in single-mode fiber tapers

The onset of transmission loss in four single-mode tapers is shown to coincide with the taper slope exceeding the critical slope angle at which fundamental mode cutoff occurs. This implies that the primary loss mechanism in single-mode fiber tapers is cutoff of the fundamental mode from the core. A secondary loss mechanism of coupling to the modes of a coaxial outer waveguide is also observed and modeled. Implications for fused fiber couplers are discussed.     

Noise characterization of a mode-locked InGaAsP semiconductor diodelaser

Noise measurements were made on an InGaAsP semiconductor diode laser by monitoring and analyzing the mode-locked pulse train power spectrum. The noise content of the mode-locking RF source was observed to be transferred directly to the laser pulse train and, thus, careful selection of the drive oscillator is essential. Amplification of the laser pulses by an erbium-fiber amplifier did not lead to any increase in timing jitter and the additional amplitude noise present could be removed by using a more compatible pump source such as a diode laser operating at either 980 or 1490 nm     

The homeless assessment program: A service-training model for providing disability evaluations for homeless, mentally ill individuals.

Many of the nation's homeless people suffer from unrecognized mental illnesses and do not have access to the kind of disability benefits they would be entitled to when properly assessed. The current system of disability evaluations for Social Security income claims is frequently inadequate and leaves these individuals without any source of income, health insurance, and mental health treatment. This article introduces a model of providing psychological assessments for homeless, mentally ill individuals by supervised student examiners, a model that could be replicated by other psychologists and training institutions. The authors argue that there may be a large number of homeless adults who suffer from disabling mental conditions but who are not properly diagnosed and, therefore, do not qualify for benefits. The authors propose that the model presented can help to fill a gap in services and may serve as a model of socially relevant clinical training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Technical note on cold weather installation of HDPE

In order to successfully seam HDPE flexible membrane liners (FMLs) in cold weather (less than 4·5°C (40°F), FML temperature may not be the most important factor. Secondary cold weather effects such as frozen subgrade, bridging, snow and ice removal, and worker discomfort pose a much more significant risk to the integrity of the liner installation.