Effect of catalyst residues on the chain structure and properties of a Phillips type polyethylen

A large number of high‐density polyethylene (HDPE) powder samples produced by Phillips technology were taken from an industrial polymerization reactor and their catalyst residue content was determined by X‐ray fluorescence spectroscopy. The chemical structure of the powder was characterized by diffuse reflectance infrared spectroscopy (DRIFT), while the functional group content of samples processed in the presence and absence of a phenolic antioxidant was determined by Fourier transform infrared spectroscopy (FTIR). The melt flow index (MFI) of all processed samples was measured. Oxygen induction time (OIT) measurements were carried out to characterize the oxidative stability of 15 selected stabilized samples. The results indicate that the distribution of both the amount of chromium‐based catalyst residues and their composition are very heterogeneous in the produced polymer. With increasing catalyst residue content, the concentration of double bonds increases in the samples extruded with or without stabilizer. Viscosity was not influenced by catalyst residues, while discoloration increased slightly with increasing catalyst residue content. The stability of the processed polymer also depends on the concentration of double bonds and on other factors. Since other components of the catalyst, including the SiO₂ support, also take part in the reactions occurring during processing, chromium content is not the sole, and perhaps not even the decisive, factor determining the properties and especially the stability of HDPE produced by a Phillips catalyst.     

Review of the evidence base for treatment of childhood psychopathology: Internalizing disorders.

This article reviews the empirical literature on psychosocial, psychopharmacological, and adjunctive treatments for children between the ages of 6 and 12 with internalizing disorders. The aim of this review was to identify interventions that have potential to prevent substance use disorders in adolescence by treating internalizing disorders in childhood. Results suggest that a variety of behavioral, cognitive-behavioral, and pharmacological interventions are effective in reducing symptoms of childhood depression, phobias, and anxiety disorders. None of the studies reviewed included substance abuse outcomes. Thus, little can be said about the relationship between early treatment and the prevention of later substance use. The importance of evaluating the generalizability of research-supported interventions to community settings is highlighted and recommendations for future research are offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Randomised trial of one versus two doses of prostaglandin E2 for induction of labour: 2. Analysis of cost

OBJECTIVE: To compare the impact upon maternity unit resources and finances of two protocols for induction of labour using prostaglandins. DESIGN: A prospective randomised trial comparing a single dose of prostaglandin E2 (2 mg) in the evening with two doses of prostaglandin E2 (2 mg), the second being given after six hours if labour had not started or the cervix was still unripe, followed if necessary by formal induction of labour by amniotomy and oxytocin infusion 14 to 20 hours after the initial prostaglandin E2 dose. Outcome for nulliparae and multiparae were analysed separately, by treatment intention. SETTING: A maternity unit in a district general hospital delivering > 6000 women annually. PARTICIPANTS: Nine hundred and fifty-five women with viable singleton pregnancies and cephalic presentation at term without previous history of caesarean section who were advised to have labour induced with prostaglandins. MAIN OUTCOME MEASURES: Costs incurred in managing all aspects of labour, including time spent on the antenatal ward and, in the delivery unit; costs associated with formal induction, augmentation of labour and epidural analgesia; costs of intrapartum maternal morbidity, mode of delivery and immediate neonatal care. Costs of postpartum hospital stay were estimated from unit statistics. RESULTS: The overall mean cost of induction of labour was Pounds 5.00 and Pounds 7.22 less per woman for nulliparae and multiparae, respectively, if the two dose regimen was used. The main reason for the differences was due to delivery suite costs from the slightly greater rate of assisted deliveries in the single treatment groups. In contrast, costs for neonatal care were marginally lower if only one prostaglandin dose was used. CONCLUSIONS: The increased drug costs providing two prostaglandin E2 doses when required were off-set by reductions in the costs of other intrapartum interventions for both nulliparae and multiparae. The advantages of less time spent on the antenatal ward for multiparae when two prostaglandin E2 doses were used may be eliminated if amniotomy and oxytocin infusion was commenced six hours after the initial prostaglandin dose had been given if labour had not started.     

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)