A diode for correction-less small field output factor measurements

Introduction Due to their high spatial resolution diodes are often used for small field relative output factor measurements. However, a field size specific correction factor [1] is required and corrects for diode detector over-response at small field sizes. A recent Monte Carlo based study has shown that it is possible to design a diode detector that produces measured relative output factors that are equivalent to those in water. This is accomplished by introducing an air gap at the upstream end of the diode [2]. The aim of this study was to physically construct this diode by placing an ‘air cap’ on the end of a commercially available diode (the PTW 60016 electron diode). The output factors subsequently measured with the new diode design were compared to current benchmark small field output factor measurements. Methods A water-tight ‘cap’ was constructed so that it could be placed over the upstream end of the diode. The cap was able to be offset from the end of the diode, thus creating an air gap. The air gap width was the same as the diode width (7 mm) and the thickness of the air gap could be varied. Output factor measurements were made using square field sizes of side length from 5 to 50 mm, using a 6 MV photon beam. The set of output factor measurements were repeated with the air gap thickness set to 0, 0.5, 1.0 and 1.5 mm. The optimal air gap thickness was found in a similar manner to that proposed by Charles et al. [2]. An IBA stereotactic field diode, corrected using Monte Carlo calculated kq,clin,kq,msr values [3] was used as the gold standard. Results The optimal air thickness required for the PTW 60016 electron diode was 1.0 mm. This was close to the Monte Carlo predicted value of 1.15 mm2. The sensitivity of the new diode design was independent of field size (kq,clin,kq,msr = 1.000 at all field sizes) to within 1 %. Discussion and conclusions The work of Charles et al. [2] has been proven experimentally. An existing commercial diode has been converted into a correction-less small field diode by the simple addition of an ‘air cap’. The method of applying a cap to create the new diode leads to the diode being dual purpose, as without the cap it is still an unmodified electron diode.

Dispositional resistance to change : measurement equivalence and the link to personal values across 17 nations

The concept of dispositional resistance to change has been introduced in a series of exploratory and confirmatory analyses through which the validity of the Resistance to Change (RTC) Scale has been established (S. Oreg, 2003). However, the vast majority of participants with whom the scale was validated were from the United States. The purpose of the present work was to examine the meaningfulness of the construct and the validity of the scale across nations. Measurement equivalence analyses of data from 17 countries, representing 13 languages and 4 continents, confirmed the cross-national validity of the scale. Equivalent patterns of relationships between personal values and RTC across samples extend the nomological net of the construct and provide further evidence that dispositional resistance to change holds equivalent meanings across nations.

Children's perspectives on values and rules in Australian early education

In recent years, issues relating to moral and conventional values have been emphasized in educational policies. This study examines young children’s (100 children aged 4–8 years) own understandings of values and rules for how to treat others and participate in school. Eleven classrooms, within seven different elementary schools in Queensland, were visited. Children were interviewed regarding their views about moral and conventional issues, rules and participation in everyday school life. According to the children, ‘doing the right thing’ in school involved both a concern for others’ wellbeing and for the social order in school, including conventions, rules and behaviour connected with discipline. The children’s responsibility seemed, however, to be to adapt to the (school) system, rather than being an active participant in constructing the system.

Identification and Validity of Accelerometer Cut-Points for Toddlers

The purpose of this study was to derive ActiGraph cut-points for sedentary (SED), light-intensity physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) in toddlers and evaluate their validity in an independent sample. The predictive validity of established preschool cut-points were also evaluated and compared. Twenty-two toddlers (mean age = 2.1 years ± 0.4 years) wore an ActiGraph accelerometer during a videotaped 20-min play period. Videos were subsequently coded for physical activity (PA) intensity using the modified Children's Activity Rating Scale (CARS). Receiver operating characteristic (ROC) curve analyses were conducted to determine cut-points. Predictive validity was assessed in an independent sample of 18 toddlers (mean age = 2.3 ± 0.4 years). From the ROC curve analyses, the 15-s count ranges corresponding to SED, LPA, and MVPA were 0–48, 49–418, and >418 counts/15 s, respectively. Classification accuracy was fair for the SED threshold (ROC-AUC = 0.74, 95% confidence interval = 0.71–0.76) and excellent for MVPA threshold (ROC-AUC = 0.90, 95% confidence interval = 0.88–0.92). In the cross-validation sample, the toddler cut-point and established preschool cut-points significantly overestimated time spent in SED and underestimated time in spent in LPA. For MVPA, mean differences between observed and predicted values for the toddler and Pate cut-points were not significantly different from zero. In summary, the ActiGraph accelerometer can provide useful group-level estimates of MVPA in toddlers. The results support the use of the Pate cut-point of 420 counts/15 s for MVPA.

Validity of the computer science and applications (CSA) activity monitor in children

Purpose The purpose of this study was to evaluate the validity of the CSA activity monitor as a measure of children's physical activity using energy expenditure (EE) as a criterion measure. Methods Thirty subjects aged 10 to 14 performed three 5-min treadmill bouts at 3, 4, and 6 mph, respectively. While on the treadmill, subjects wore CSA (WAM 7164) activity monitors on the right and left hips. (V) over dot O-2 was monitored continuously by an automated system. EE was determined by multiplying the average (V) over dot O-2 by the caloric equivalent of the mean respiratory exchange ratio. Results Repeated measures ANOVA indicated that both CSA monitors were sensitive to changes in treadmill speed. Mean activity counts from each CSA unit were not significantly different and the intraclass reliability coefficient for the two CSA units across all speeds was 0.87. Activity counts from both CSA units were strongly correlated with EE (r = 0.86 and 0.87, P < 0.001). An EE prediction equation was developed from 20 randomly selected subjects and cross-validated on the remaining 10. The equation predicted mean EE within 0.01 kcal.min(-1). The correlation between actual and predicted values was 0.93 (P < 0.01) and the SEE was 0.93 kcal.min(-1). Conclusion These data indicate that the CSA monitor is a valid and reliable tool for quantifying treadmill walking and running in children.

The free encyclopaedia that anyone can edit: the shifting values of Wikipedia editors

Wikipedia is often held up as an example of the potential of the internet to foster open, free and non-commercial collaboration. However such discourses often conflate these values without recognising how they play out in reality in a peer-production community. As Wikipedia is evolving, it is an ideal time to examine these discourses and the tensions that exist between its initial ideals and the reality of commercial activity in the encyclopaedia. Through an analysis of three failed proposals to ban paid advocacy editing in the English language Wikipedia, this paper highlights the shift in values from the early editorial community that forked encyclopaedic content over the threat of commercialisation, to one that today values the freedom that allows anyone to edit the encyclopaedia.

Internal oscillating current-sustained RF plasmas : Parameters, stability, and potential for surface engineering

A new source of low-frequency (0.46 MHz) inductively coupled plasmas sustained by the internal planar "unidirectional" RF current driven through a specially designed internal antenna configuration has been developed. The experimental results of the investigation of the optical and global argon plasma parameters by the optical and Langmuir probes are presented. It is shown that the spatial profiles of the electron density, the effective electron temperature and plasma potential feature a great deal of the radial and axial uniformity compared with conventional sources of inductively coupled plasmas with external at coil configurations. The measurements also reveal a weak azimuthal dependence of the global plasma parameters at low values of the input RF power, which was earlier predicted theoretically. The azimuthal dependence of the global plasma parameters vanishes at high input RF powers. Moreover, under certain conditions, the plasma becomes unstable due to spontaneous transitions between low-density (electrostatic, E) and high-density (electromagnetic, H) operating modes. Excellent uniformity of high-density plasmas makes the plasma reactor promising for various plasma processing applications and surface engineering.

Comparison of eight published static finite element models of the intact lumbar spine : predictive power of models improves when combined together

Finite element (FE) model studies have made important contributions to our understanding of functional biomechanics of the lumbar spine. However, if a model is used to answer clinical and biomechanical questions over a certain population, their inherently large inter-subject variability has to be considered. Current FE model studies, however, generally account only for a single distinct spinal geometry with one set of material properties. This raises questions concerning their predictive power, their range of results and on their agreement with in vitro and in vivo values. Eight well-established FE models of the lumbar spine (L1-5) of different research centres around the globe were subjected to pure and combined loading modes and compared to in vitro and in vivo measurements for intervertebral rotations, disc pressures and facet joint forces. Under pure moment loading, the predicted L1-5 rotations of almost all models fell within the reported in vitro ranges, and their median values differed on average by only 2° for flexion-extension, 1° for lateral bending and 5° for axial rotation. Predicted median facet joint forces and disc pressures were also in good agreement with published median in vitro values. However, the ranges of predictions were larger and exceeded those reported in vitro, especially for the facet joint forces. For all combined loading modes, except for flexion, predicted median segmental intervertebral rotations and disc pressures were in good agreement with measured in vivo values. In light of high inter-subject variability, the generalization of results of a single model to a population remains a concern. This study demonstrated that the pooled median of individual model results, similar to a probabilistic approach, can be used as an improved predictive tool in order to estimate the response of the lumbar spine.

Quantifying economic values of coastal and marine ecosystem services and assessing their use in decision-making : applications in New Caledonia and Australia

This thesis deals with the issues of quantifying economic values of coastal and marine ecosystem services and assessing their use in decision-making. The first analytical part of the thesis focuses on estimating non-market use and non-use values, with an application in New-Caledonia using Discrete Choice Experiment. The second part examines how and to what extent the economic valuation of ecosystem services is used in coastal management decision-making with an application in Australia. Using a multi-criteria analysis, the relative importance of ecological, social and economic evaluation criteria is also assessed in the context of coastal development.

Visions and values : the Children’s Book Council of Australia’s prizing of picture books in the twenty-first century

The Children’s Book Council of Australia (CBCA) administers the oldest national prize for children’s literature in Australia. Each year, the CBCA confers “Book of the Year” awards to literature for young people in five categories. In 2001, the establishment of an “Early Childhood” category opened up the venerable “Picture Book” category (first awarded in 1955) to books with an implied readership up to 18 years of age. As a result, this category has emerged in recent years as a highly visible space within which the CBCA can contest discourses of cultural marginalisation insofar as Australian (“colonial”) literature is constructed as inferior or adjunct to the major Anglophone literary traditions, and the consistent identification of children’s literature (and, indeed, of children) as lesser than its ‘adult’ counterparts. The CBCA is engaged in defining, evaluating, and legitimising a tradition of Australian children’s literature which is underpinned by a canonical impulse, and is a reflexive practice of self-definition, self-evaluation and self-legitimisation for the CBCA itself. While it is obviously problematic to identify award winners as a canon, it is equally obvious that literary prizing is a cultural practice derived from the logic of canonicity. In his discussion of the United States’s Newbery Medal, Kenneth Kidd notes that “Medal books are instant classics, the selection process an ostensible simulation of the test of time” (169) and that “the Medal is part of the canonical architecture of children's literature” (169). Thus, it is instructive to consider the visions and values of the national, of the social, and of the literary-aesthetic, in the picture books chosen by the Children’s Book Council of Australia (CBCA) as the “best” of the early twenty-first century. These books not only constitute a kind of canon for contemporary Australian children’s literature, but may well come to define what contemporary Australian children’s literature means in the wider literary field. The Book of the Year: Picture Book awards given by the CBCA since 2001 demonstrate that it is not only true of the Booker Prize that, “The choices of winning books reflect not only on the books themselves, then, but also back on the Prize, affecting its reputation and creating journalistic capital which is vital for the Prize to achieve its prominence and impact.” (81). Many of the twenty-first century CBCA award-winning picture books complicate traditional or comfortable understanding of Australianness, children’s literature, or “appropriate” modes of form and content, reminding us that “moments when texts resist or complicate recuperation into national discourses offer fruitful points for exploring the relationships between text and celebratory context” (Roberts 6). The CBCA has taken the opportunities offered by the liberation of the Picture Book category from an implied readership to challenge dominant constructions of children’s literature in Australia, and in so doing, are engaged in overt practices of canonicity with potentially long-lasting effects. Works Cited: Kidd, Kenneth. “Prizing Children’s Literature: The Case of Newbery Gold.” Children's Literature 35 (2007): 166-190. Roberts, Gillian. Prizing Literature: The Celebration and Circulation of National Culture. Toronto: U Toronto P, 2011. Squires, Claire. “Book Marketing and the Booker Prize.” Judging a Book by Its Cover: Fans, Publishers, Designers, and the Marketing of Fiction. Eds. Nicole Matthews and Nickianne Moody. Aldershot: Ashgate, 2007. 71-82.

Biological monitoring and Biological Limit Values (BLV): the strategy of the European Union

Occupational standards concerning allowable concentrations of chemical compounds in the ambient air of workplaces have been established in several countries worldwide. With the integration of the European Union (EU), there has been a need of establishing harmonised Occupational Exposure Limits (OEL). The European Commission Directive 95/320/EC of 12 July 1995 has given the tasks to a Scientific Committee for Occupational Exposure Limits (SCOEL) to propose, based on scientific data and where appropriate, occupational limit values which may include the 8-h time-weighted average (TWA), short-term limits/excursion limits (STEL) and Biological Limit Values (BLVs). In 2000, the European Union issued a list of 62 chemical substances with Occupational Exposure Limits. Of these, 25 substances received a "skin" notation, indicating that toxicologically significant amounts may be taken up via the skin. For such substances, monitoring of concentrations in ambient air may not be sufficient, and biological monitoring strategies appear of potential importance in the medical surveillance of exposed workers. Recent progress has been made with respect to formulation of a strategy related to health-based BLVs.

Ethical values in emergency medical services: A pilot study

Background Ambulance professionals often address conflicts between ethical values. As individuals’ values represent basic convictions of what is right or good and motivate behaviour, research is needed to understand their value profiles. Objectives To translate and adapt the Managerial Values Profile to Spanish and Swedish, and measure the presence of utilitarianism, moral rights and/or social justice in ambulance professionals’ value profiles in Spain and Sweden. Methods The instrument was translated and culturally adapted. A content validity index was calculated. Pilot tests were carried out with 46 participants. Ethical considerations This study conforms to the ethical principles for research involving human subjects and adheres to national laws and regulations concerning informed consent and confidentiality. Findings Spanish professionals favoured justice and Swedish professionals’ rights in their ambulance organizations. Both countries favoured utilitarianism least. Gender differences across countries showed that males favoured rights. Spanish female professionals favoured justice most strongly of all. Discussion Swedes favour rights while Spaniards favour justice. Both contexts scored low on utilitarianism focusing on total population effect, preferring the opposite, individualized approach of the rights and justice perspectives. Organizational investment in a utilitarian perspective might jeopardize ambulance professionals’ moral right to make individual assessments based on the needs of the patient at hand. Utilitarianism and a caring ethos appear as stark opposites. However, a caring ethos in its turn might well involve unreasonable demands on the individual carer’s professional role. Since both the justice and rights perspectives portrayed in the survey mainly concern relationship to the organization and peers within the organization, this relationship might at worst be given priority over the equal treatment and moral rights of the patient. Conclusion A balanced view on ethical perspectives is needed to make professionals observant and ready to act optimally – especially if these perspectives are used in patient care. Research is needed to clarify how justice and rights are prioritized by ambulance services and whether or not these organization-related values are also implemented in patient care.

kmth price sealed-bid auctions with general independent values and equilibrium linear mark-ups

A generalised bidding model is developed to calculate a bidder’s expected profit and auctioners expected revenue/payment for both a General Independent Value and Independent Private Value (IPV) kmth price sealed-bid auction (where the mth bidder wins at the kth bid payment) using a linear (affine) mark-up function. The Common Value (CV) assumption, and highbid and lowbid symmetric and asymmetric First Price Auctions and Second Price Auctions are included as special cases. The optimal n bidder symmetric analytical results are then provided for the uniform IPV and CV models in equilibrium. Final comments concern implications, the assumptions involved and prospects for further research.

Nutritional support in chronic obstructive Pulmonary Disease (COPD) a randomised trial

Rationale Nutritional support is effective in managing malnutrition in COPD (Collins et al., 2012) leading to functional improvements (Collins et al., 2013). However, comparative trials of first line interventions are lacking. This randomised trial compared the effectiveness of individualised dietary advice by a dietitian (DA) versus oral nutritional supplements (ONS). Methods A target sample of 200 stable COPD outpatients at risk of malnutrition (‘MUST’; medium + high risk) were randomised to either a 12-week intervention of ONS (ONS: ~400 kcal/d, ~40 g/d protein) or DA with supportive written advice. The primary outcome was quality of life (QoL) measured using St George’s Respiratory Questionnaire with secondary outcomes including handgrip strength, body weight and nutritional intake. Both the change from baseline and the differences between groups was analysed using SPSS version 20. Results 84 outpatients were recruited (ONS: 41 vs. DA: 43), 72 completed the intervention (ONS: 33 vs. DA: 39). Mean BMI was 18.2 SD 1.6 kg/m2, age 72.6 SD 10 years, FEV1% predicted 36 SD 15% (severe COPD). In comparison to the DA group, the ONS group experienced significantly greater improvements in protein intakes above baseline values at both week 6 (+21.0 SEM 4.3 g/d vs. +0.52 SEM 4.3 g/d; p < 0.001) and week 12 (+19.0 SEM 5.0 g/d vs. +1.0 SEM 3.6 g/d; p = 0.033;ANOVA). QoL and secondary outcomes remained stable at 12 weeks in both groups with slight improvements in the ONS group but no differences between groups. Conclusion In outpatients at risk of malnutrition with severe COPD, nutritional support involving either ONS or DA appears to maintain in tritional status, functional capacity and QoL. However, larger trials, and earlier, multi-modal nutritional interventions for an extended duration should be explored.

Approximation of Bayesian predictive p-values with regression ABC

In the Bayesian framework a standard approach to model criticism is to compare some function of the observed data to a reference predictive distribution. The result of the comparison can be summarized in the form of a p-value, and it's well known that computation of some kinds of Bayesian predictive p-values can be challenging. The use of regression adjustment approximate Bayesian computation (ABC) methods is explored for this task. Two problems are considered. The first is the calibration of posterior predictive p-values so that they are uniformly distributed under some reference distribution for the data. Computation is difficult because the calibration process requires repeated approximation of the posterior for different data sets under the reference distribution. The second problem considered is approximation of distributions of prior predictive p-values for the purpose of choosing weakly informative priors in the case where the model checking statistic is expensive to compute. Here the computation is difficult because of the need to repeatedly sample from a prior predictive distribution for different values of a prior hyperparameter. In both these problems we argue that high accuracy in the computations is not required, which makes fast approximations such as regression adjustment ABC very useful. We illustrate our methods with several samples.