Periodogram Analysis of Censored Time Series from a Designed Experiment

Growth hormone plasma concentrations vary rhythmically between high and low values. Radioimmunoassay measurements of low values are often indistinguishable from low controls, and are reported as a censored value, the 'minimum detectable dose'. This paper reports such a dataset from a designed experiment with about 60% of the values censored but large distinct signals for the remainder of the data. The ordinates of the average periodogram for each treatment group are independently gamma distributed, with distribution depending on the underlying spectrum and the replication for that group. This situation can lead to an analysis for common spectral shape using a gamma generalized linear model with log link, and the hypothesis of common spectral shape is rejected here. Since such a level of censoring reduces the variance of each profile, the periodogram, which is a partition of the variance, is also reduced in overall magnitude. A simulation study shows that this reduction is not necessarily uniform over the frequency domain, but may be more pronounced at lower or higher ordinates depending on the underlying model. Therefore it is possible that the rejection of common spectral shape is an artefact of the censoring.     

Creative solutions: Innovative use of the arts in mental health settings

A recent study of occupational stress on the unit (Clare, 2004) highlighted that staff valued the importance of the socialization process in reducing their stress levels. This process incorporates the need for peer support and acceptance, and an understanding of what is expected of them (e.g., roles and responsibilities), supported by a culture of learning, problem solving, and working together. This process is similar to the approach taken by the arts project in nurturing ideas and initiatives in a safe, respectful way. It is apparent that the arts project has been more than just a creative activity; it has had wider implications for both staff and service users in reducing stress. It has: * Enabled staff retention. In fact, there is a waiting list of nurses wishing to work on the unit. * Reduced incidents of damage to property. * Reduced use of p.r.n. medication. * Enhanced the good reputation of the service, which is often commented on by visitors to the unit. The arts project promotes well-being and lifelong learning for the ward community through meaningful engagement in creative activity.     

Marital Therapy — My Style

Recipes often evolve over time and can become enshrined by chefs. I have set out my recipe on marital therapy reflecting the collected cooking wisdom of generations. My instructions and information will enable a therapist as chef to create special dishes for a variety of occasions.     

A review of inflation accounting and its economic implications

The purposes of this paper are firstly to identify the problems which inflation creates in the context of conventional accounting methods, secondly to consider the alternative forms of inflation accounting which have been proposed, thirdly to look in more detail at the particular method which is to be adopted in the UK, and finally to consider the effects which that method will have on company results and on broader economic issues.     

Rationalising knowledge: IT systems, professional identities and power

This paper explores the impact of a new IT system on the knowledge claims and occupational boundaries made by professional groups within a hospital laboratory setting. Within organizational settings professional groups enjoy considerable power and status through the specialised knowledge claims they make, deploying a variety of material and discursive resources to secure these. However, when organizations introduce new technologies to manage information needs, professional boundaries and claims to expertise may be threatened. This paper examines the strategies deployed by two key professional groups – Medical Laboratory Scientific Officers and medics – to secure their knowledge claims and statuses within the new organizational context shaped in part by an IT system. Though medics were more successful here, they had to accommodate to new demands within the organization. The professional identity and organizational space of the MLSOs were also redefined but, in contrast, by being narrowed. The different experiences and strategies of the two groups reflect their unequal holding of cultural capital and their differential capacity to define their status relative to the organization itself.     

Social Perception in Students with Learning Disabilities and Attention-Deficit/Hyperactivity Disorder

The current study investigated whether students' classification of learning disabled (LD), learning disabled with attention-deficit/hyperactivity disorder (LD/ADHD), or no classification (REG) was related to their ability to perceive nonverbal social cues. Participants in the study were 57 students between the ages of six and ten years identified as being LD, LD/ADHD, or REG. The Diagnostic Analysis of Nonverbal Accuracy test (DANVA) and the Social Perception Behavior Rating Scale (SPBRS) were used to measure social perception. A MANOVA was computed for the four subtests of the DANVA (Facial Expressions, Postures, Gestures, and Paralanguage). A separate ANOVA was computed on the SPBRS. Significant differences were found for Facial Expressions and SPBRS scores. Follow-up analysis revealed that on the Facial Expressions subtest, students with LD demonstrated significantly more difficulty in the accurate perception of cues than the REG or LD/ ADHD groups. On the SPBRS, the LD/ADHD group was rated by teachers as significantly less socially perceptive than the REG group.     

A Comparison of Methods of Benchmark-Dose Estimation for Continuous Response Data

Methods of quantitative risk assessment for toxic responses that are measured on a continuous scale are not well established. Although risk-assessment procedures that attempt to utilize the quantitative information in such data have been proposed, there is no general agreement that these procedures are appreciably more efficient than common quantal dose–response procedures that operate on dichotomized continuous data. This paper points out an equivalence between the dose–response models of the nonquantal approach of Kodell and West⁽¹⁾ and a quantal probit procedure, and provides results from a Monte Carlo simulation study to compare coverage probabilities of statistical lower confidence limits on dose corresponding to specified additional risk based on applying the two procedures to continuous data from a dose–response experiment. The nonquantal approach is shown to be superior, in terms of both statistical validity and statistical efficiency.     

Dynamic Pricing and Lead‐Time Policies for Make‐to‐Order Systems*

Make‐to‐order firms use different approaches for managing their lead‐times and pricing in the face of changing market conditions. A particular firm's approach may be largely dictated by environmental constraints. For example, it makes little sense to carefully manage lead‐time if its effect on demand is muted, as it can be in situations where leadtime is difficult for the market to gauge or requires investment to estimate. Similarly, it can be impractical to change capacity and price. However, environmental constraints are likely to become less of an issue in the future with the expanding e‐business infrastructure, and this trend raises questions into how to manage effectively the marketing mix of price and lead‐time in a more “friction‐free” setting. We study a simple model of a make‐to‐order firm, and we examine policies for adjusting price and capacity in response to periodic and unpredictable shifts in how the market values price and lead‐time. Our analysis suggests that maintaining a fixed capacity while using lead‐time and/or price to absorb changes in the market will be most attractive when stability in throughput and profit are highly valued, but in volatile markets, this stability comes at a cost of low profits. From a pure profit maximization perspective, it is best to strive for a short and consistent lead‐times by adjusting both capacity and price in response to market changes.     

The association of unresolved attachment status and cognitive processes in maltreated adolescents

This exploratory investigation sought to gain a better understanding of the mental representations of attachment in maltreated adolescents, and how, if at all, unresolved attachment representations are related to cognitive processes in this population. Measures of cognitive functioning, attachment state of mind and parent ratings on attention were obtained from 38 adolescents with a history of maltreatment. Results showed that maltreated adolescents with unresolved states of mind in regard to attachment scored significantly lower on measures of cognitive processes of attention, working memory and cognitive efficiency, even when intelligence was controlled for in the analyses. Theoretical considerations, implications for future research and clinical implications are discussed. Copyright © 2009 John Wiley & Sons, Ltd.