An investigation of dose calculation accuracy in intensity-modulated radiotherapy of sites in the head & neck

Knowledge of the accuracy of dose calculations in intensity-modulated radiotherapy of the head and neck is essential for clinical confidence in these highly conformal treatments. High dose gradients are frequently placed very close to critical structures, such as the spinal cord, and good coverage of complex shaped nodal target volumes is important for long term-local control. A phantom study is presented comparing the performance of standard clinical pencil-beam and collapsed-cone dose algorithms to Monte Carlo calculation and three-dimensional gel dosimetry measurement. All calculations and measurements are normalized to the median dose in the primary planning target volume, making this a purely relative study. The phantom simulates tissue, air and bone for a typical neck section and is treated using an inverse-planned 5-field IMRT treatment, similar in character to clinically used class solutions. Results indicate that the pencil-beam algorithm fails to correctly model the relative dose distribution surrounding the air cavity, leading to an overestimate of the target coverage. The collapsed-cone and Monte Carlo results are very similar, indicating that the clinical collapsed-cone algorithm is perfectly sufficient for routine clinical use. The gel measurement shows generally good agreement with the collapsed-cone and Monte Carlo calculated dose, particularly in the spinal cord dose and nodal target coverage, thus giving greater confidence in the use of this class solution.

Incorporating weather into regionwide safety planning prediction models

Predicting safety on roadways is standard practice for road safety professionals and has a corresponding extensive literature. The majority of safety prediction models are estimated using roadway segment and intersection (microscale) data, while more recently efforts have been undertaken to predict safety at the planning level (macroscale). Safety prediction models typically include roadway, operations, and exposure variables—factors known to affect safety in fundamental ways. Environmental variables, in particular variables attempting to capture the effect of rain on road safety, are difficult to obtain and have rarely been considered. In the few cases weather variables have been included, historical averages rather than actual weather conditions during which crashes are observed have been used. Without the inclusion of weather related variables researchers have had difficulty explaining regional differences in the safety performance of various entities (e.g. intersections, road segments, highways, etc.) As part of the NCHRP 8-44 research effort, researchers developed PLANSAFE, or planning level safety prediction models. These models make use of socio-economic, demographic, and roadway variables for predicting planning level safety. Accounting for regional differences - similar to the experience for microscale safety models - has been problematic during the development of planning level safety prediction models. More specifically, without weather related variables there is an insufficient set of variables for explaining safety differences across regions and states. Furthermore, omitted variable bias resulting from excluding these important variables may adversely impact the coefficients of included variables, thus contributing to difficulty in model interpretation and accuracy. This paper summarizes the results of an effort to include weather related variables, particularly various measures of rainfall, into accident frequency prediction and the prediction of the frequency of fatal and/or injury degree of severity crash models. The purpose of the study was to determine whether these variables do in fact improve overall goodness of fit of the models, whether these variables may explain some or all of observed regional differences, and identifying the estimated effects of rainfall on safety. The models are based on Traffic Analysis Zone level datasets from Michigan, and Pima and Maricopa Counties in Arizona. Numerous rain-related variables were found to be statistically significant, selected rain related variables improved the overall goodness of fit, and inclusion of these variables reduced the portion of the model explained by the constant in the base models without weather variables. Rain tends to diminish safety, as expected, in fairly complex ways, depending on rain frequency and intensity.

Adherence to medicines in the older-aged with chronic conditions : does an intervention concerning adherence by an allied health professional help?

Adherence to medicines is a major determinant of the effectiveness of medicines. However, estimates of non-adherence in the older-aged with chronic conditions vary from 40 to 75%. The problems caused by non-adherence in the older-aged include residential care and hospital admissions, progression of the disease, and increased costs to society. The reasons for non-adherence in the older-aged include items related to the medicine (e.g. cost, number of medicines, adverse effects) and those related to person (e.g. cognition, vision, depression). It is also known that there are many ways adherence can be increased (e.g. use of blister packs, cues). It is assumed that interventions by allied health professions, including a discussion of adherence, will improve adherence to medicines in the older aged but the evidence for this has not been reviewed. There is some evidence that telephone counselling about adherence by a nurse or pharmacist does improve adherence, short- and long-term. However, face-to-face intervention counselling at the pharmacy, or during a home visit by a pharmacist, has shown variable results with some studies showing improved adherence and some not. Education programs during hospital stays have not been shown to improve adherence on discharge, but education programs for subjects with hypertension have been shown to improve adherence. In combination with an education program, both counselling and a medicine review program have been shown to improve adherence short-term in the older-aged. Thus, there are many unanswered questions about the most effective interventions to promote adherence. More studies are needed to determine the most appropriate interventions by allied health professions, and these need to consider the disease state, demographics, and socio-economic status of the older-aged subject, and the intensity and duration of intervention needed.

A two-Dimensional finite volume method for variable density flow and solute transport through saturated-unsaturated media

Extensive groundwater withdrawal has resulted in a severe seawater intrusion problem in the Gooburrum aquifers at Bundaberg, Queensland, Australia. Better management strategies can be implemented by understanding the seawater intrusion processes in those aquifers. To study the seawater intrusion process in the region, a two-dimensional density-dependent, saturated and unsaturated flow and transport computational model is used. The model consists of a coupled system of two non-linear partial differential equations. The first equation describes the flow of a variable-density fluid, and the second equation describes the transport of dissolved salt. A two-dimensional control volume finite element model is developed for simulating the seawater intrusion into the heterogeneous aquifer system at Gooburrum. The simulation results provide a realistic mechanism by which to study the convoluted transport phenomena evolving in this complex heterogeneous coastal aquifer.

Civic engagement and associationalism : the impact of group membership scope versus intensity of participation

The relationship between participation in civic and political activities and membership of voluntary associations is now well established. What is less clear is the relative impacts of how much time people spend on group activities (associational intensity), and the number and type of groups that individuals are involved with (associational scope). Does it matter in terms of civic engagement, for example, whether one is a member of a quilting-circle or trade union? Does it matter whether association ‘membership’ is simply an annual payment or a major commitment of time and energy? In this article, we use a large survey to explore these questions empirically by focusing on the membership patterns and civic engagement practices of 4,001 citizens drawn from eight suburbs across Greater Melbourne, Australia. Our findings indicate that, while associational intensity is positively related to civic engagement, associational scope (the number of group memberships per person), is a more influential determinant of the level of civic and political participation. The results also suggest that while all forms of associationalism are important in terms of fostering greater levels of civic activity, not all forms have the same impact.

Internet usage, internet marketing intensity and international marketing growth

This paper examines the role of the Internet in international marketing growth. Evidence of a positive relationship between e-mail, website usage, online marketing and advertising with international market growth was found, in terms of increased sales from new customers in new countries, new customers in existing countries, and existing customers.

Models of collective cell spreading with variable cell aspect ratio : a motivation for degenerate diffusion models

Continuum diffusion models are often used to represent the collective motion of cell populations. Most previous studies have simply used linear diffusion to represent collective cell spreading, while others found that degenerate nonlinear diffusion provides a better match to experimental cell density profiles. In the cell modeling literature there is no guidance available with regard to which approach is more appropriate for representing the spreading of cell populations. Furthermore, there is no knowledge of particular experimental measurements that can be made to distinguish between situations where these two models are appropriate. Here we provide a link between individual-based and continuum models using a multi-scale approach in which we analyze the collective motion of a population of interacting agents in a generalized lattice-based exclusion process. For round agents that occupy a single lattice site, we find that the relevant continuum description of the system is a linear diffusion equation, whereas for elongated rod-shaped agents that occupy L adjacent lattice sites we find that the relevant continuum description is connected to the porous media equation (pme). The exponent in the nonlinear diffusivity function is related to the aspect ratio of the agents. Our work provides a physical connection between modeling collective cell spreading and the use of either the linear diffusion equation or the pme to represent cell density profiles. Results suggest that when using continuum models to represent cell population spreading, we should take care to account for variations in the cell aspect ratio because different aspect ratios lead to different continuum models.

Low intensity CBT by mail

Introduction: There are many low intensity (LI) cognitive behavoural therapy (CBT) solutions to the problem of limited service access. In this chapter, we aim to discuss a relatively low-technology approach to access using standard postal services-CBT by mail, or M-CBT. Bibliotherapies including M-CBT teach key concepts and self-management techniques, together with screening tools and forms to structure home practice. M-CBT differs from other bibliotherapies by segmenting interventions and mailing them at regular intervals. Most involve participants returning copies of monitoring forms or completed handouts. Therapist feedback is provided, often in personal letters that accompany the printed materials. Participants may also be given access to telephone or email support. ----- ----- M-CBT clearly fulfills criteria for an LI CBT (see Bennett-Levy et al., Chapter 1, for a definition of LI interventions). Once written, they involve little therapist time and rely heavily on self-management. However, content and overall treatment duration need not be compromised. Long-term interventions with multiple components can be delivered via this method, provided their content can be communicated in letters and engagement is maintained.

Implementing low intensity CBT in case management of clients with severe mental illness

In a previous chapter (Dean and Kavanagh, Chapter 37), the authors made a case for applying low intensity (LI) cognitive behaviour therapy (CBT) to people with serious mental illness (SMI). As in other populations, LI CBT interventions typically deal with circumscribed problems or behaviours. LI CBT retains an emphasis on self-management, has restricted content and segment length, and does not necessarily require extensive CBT training. In applying these interventions to SMI, adjustments may be needed to address cognitive and symptomatic difficulties often faced by these groups. What may take a single session in a less affected population may require several sessions or a thematic application of the strategy within case management. In some cases, the LI CBT may begin to appear more like a high-intensity (HI) intervention, albeit simple and with many LI CBT characteristics still retained. So, if goal setting were introduced in one or two sessions, it could clearly be seen as an LI intervention. When applied to several different situations and across many sessions, it may be indistinguishable from a simple HI treatment, even if it retains the same format and is effectively applied by a practitioner with limited CBT training. ----- ----- In some ways, LI CBT should be well suited to case management of patients with SMI. treating staff typically have heavy workloads, and find it difficult to apply time-consuming treatments (Singh et al. 2003). LI CBT may allow provision of support to greater numbers of service users, and allow staff to spend more time on those who need intensive and sustained support. However, the introduction of any change in practice has to address significant challenges, and LI CBT is no exception. ----- ----- Many of the issues that we face in applying LI CBT to routine case management in a mnetal health service and their potential solutions are essentially the same as in a range of other problem domains (Turner and Sanders 2006)- and, indeed, are similar to those in any adoption of innovation (Rogers 2003). Over the last 20 years, several commentators have described barriers to implementing evidence-based innovations in mental health services (Corrigan et al. 1992; Deane et al. 2006; Kavanagh et al. 1993). The aim of the current chapter is to present a cognitive behavioural conceptualisation of problems and potential solutions for dissemination of LI CBT.

Adapting low intensity CBT interventions for clients with severe mental illness

Many people with severe mental illness (SMI) such as schizophrenia, whose psychotic symptoms are effectively managed, continue to experience significant functional problems. This chapter argues that low intensity (LI) cognitive behaviour therapy (CBT; e.g. for depression, anxiety, or other issues) is applicable to these clients, and that LI CBT can be consistent with long-term case management. However, adjustments to LI CBT strategies are often necessary and boundaries between LI CBT and high intensity (HI) CBT (with more extensive practitioner contact and complexity) may become blurred. Our focus is on LI CBT's self-management emphasis, its restricted content and segment length, and potential use after limited training. In addition to exploring these issues, it draws on the authors' Collaborative Recovery (CR; Oades et al. 2005) and 'Start Over and Survive' programs (Kavanagh et al. 2004) as examples. ----- ----- Evidence for the effectiveness of LI CBT with severe mental illness is often embedded within multicomponent programs. For example, goal setting and therapeutic homework are common components of such programs, but they can also be used as discrete LI CBT interventions. A review of 40 randomised controlled trials involving recipients with schizophrenia or other sever mental illnesses has identified key components of illness management programs (Mueser et al. 2002). However, it is relatively rare for specific components of these complex interventions to be assessed in isolation. Given these constraints, the evidence for specific LI CBT interventions with severe mental ilnness is relatively limited.

Variable structure control for power systems stabilization

The application of variable structure control (VSC) for power systems stabilization is studied in this paper. It is the application, aspects and constraints of VSC which are of particular interest. A variable structure control methodology has been proposed for power systems stabilization. The method is implemented using thyristor controlled series compensators. A three machine power system is stabilized using a switching line control for large disturbances which becomes a sliding control as the disturbance becomes smaller. The results demonstrate the effectiveness of the methodology proposed as an useful tool to suppress the oscillations in power systems.

A forensic investigation of single human hair fibres using FTIR-ATR spectroscopy and chemometrics

Human hair fibres are ubiquitous in nature and are found frequently at crime scenes often as a result of exchange between the perpetrator, victim and/or the surroundings according to Locard's Principle. Therefore, hair fibre evidence can provide important information for crime investigation. For human hair evidence, the current forensic methods of analysis rely on comparisons of either hair morphology by microscopic examination or nuclear and mitochondrial DNA analyses. Unfortunately in some instances the utilisation of microscopy and DNA analyses are difficult and often not feasible. This dissertation is arguably the first comprehensive investigation aimed to compare, classify and identify the single human scalp hair fibres with the aid of FTIR-ATR spectroscopy in a forensic context. Spectra were collected from the hair of 66 subjects of Asian, Caucasian and African (i.e. African-type). The fibres ranged from untreated to variously mildly and heavily cosmetically treated hairs. The collected spectra reflected the physical and chemical nature of a hair from the near-surface particularly, the cuticle layer. In total, 550 spectra were acquired and processed to construct a relatively large database. To assist with the interpretation of the complex spectra from various types of human hair, Derivative Spectroscopy and Chemometric methods such as Principal Component Analysis (PCA), Fuzzy Clustering (FC) and Multi-Criteria Decision Making (MCDM) program; Preference Ranking Organisation Method for Enrichment Evaluation (PROMETHEE) and Geometrical Analysis for Interactive Aid (GAIA); were utilised. FTIR-ATR spectroscopy had two important advantages over to previous methods: (i) sample throughput and spectral collection were significantly improved (no physical flattening or microscope manipulations), and (ii) given the recent advances in FTIR-ATR instrument portability, there is real potential to transfer this work.s findings seamlessly to on-field applications. The "raw" spectra, spectral subtractions and second derivative spectra were compared to demonstrate the subtle differences in human hair. SEM images were used as corroborative evidence to demonstrate the surface topography of hair. It indicated that the condition of the cuticle surface could be of three types: untreated, mildly treated and treated hair. Extensive studies of potential spectral band regions responsible for matching and discrimination of various types of hair samples suggested the 1690-1500 cm^-1 IR spectral region was to be preferred in comparison with the commonly used 1750-800 cm^-1. The principal reason was the presence of the highly variable spectral profiles of cystine oxidation products (1200-1000 cm^-1), which contributed significantly to spectral scatter and hence, poor hair sample matching. In the preferred 1690-1500 cm^-1 region, conformational changes in the keratin protein attributed to the α-helical to β-sheet transitions in the Amide I and Amide II vibrations and played a significant role in matching and discrimination of the spectra and hence, the hair fibre samples. For gender comparison, the Amide II band is significant for differentiation. The results illustrated that the male hair spectra exhibit a more intense β-sheet vibration in the Amide II band at approximately 1511 cm^-1 whilst the female hair spectra displayed more intense α-helical vibration at 1520-1515cm^-1. In terms of chemical composition, female hair spectra exhibit greater intensity of the amino acid tryptophan (1554 cm^-1), aspartic and glutamic acid (1577 cm^-1). It was also observed that for the separation of samples based on racial differences, untreated Caucasian hair was discriminated from Asian hair as a result of having higher levels of the amino acid cystine and cysteic acid. However, when mildly or chemically treated, Asian and Caucasian hair fibres are similar, whereas African-type hair fibres are different. In terms of the investigation's novel contribution to the field of forensic science, it has allowed for the development of a novel, multifaceted, methodical protocol where previously none had existed. The protocol is a systematic method to rapidly investigate unknown or questioned single human hair FTIR-ATR spectra from different genders and racial origin, including fibres of different cosmetic treatments. Unknown or questioned spectra are first separated on the basis of chemical treatment i.e. untreated, mildly treated or chemically treated, genders, and racial origin i.e. Asian, Caucasian and African-type. The methodology has the potential to complement the current forensic analysis methods of fibre evidence (i.e. Microscopy and DNA), providing information on the morphological, genetic and structural levels.

Calibration and operational analysis of variable speed limits for high flow condition

Variable Speed Limits (VSL) is a control tool of Intelligent Transportation Systems (ITS) which can enhance traffic safety and which has the potential to contribute to traffic efficiency. This study presents the results of a calibration and operational analysis of a candidate VSL algorithm for high flow conditions on an urban motorway of Queensland, Australia. The analysis was done using a framework consisting of a microscopic simulation model combined with runtime API and a proposed efficiency index. The operational analysis includes impacts on speed-flow curve, travel time, speed deviation, fuel consumption and emission.

Numerical simulation for the variable-order Galilei invariant advection diffusion equation with a nonlinear source term

In this paper, we consider the variable-order Galilei advection diffusion equation with a nonlinear source term. A numerical scheme with first order temporal accuracy and second order spatial accuracy is developed to simulate the equation. The stability and convergence of the numerical scheme are analyzed. Besides, another numerical scheme for improving temporal accuracy is also developed. Finally, some numerical examples are given and the results demonstrate the effectiveness of theoretical analysis. Keywords: The variable-order Galilei invariant advection diffusion equation with a nonlinear source term; The variable-order Riemann–Liouville fractional partial derivative; Stability; Convergence; Numerical scheme improving temporal accuracy