A simple test for cointegration in dependent panels with structural breaks

This paper develops a very simple test for the null hypothesis of no cointegration in panel data. The test is general enough to allow for heteroskedastic and serially correlated errors, unit-specific time trends, cross-sectional dependence and unknown structural breaks in both the intercept and slope of the cointegrated regression, which may be located at different dates for different units. The limiting distribution of the test is derived, and is found to be normal and free of nuisance parameters under the null. A small simulation study is also conducted to investigate the small-sample properties of the test. In our empirical application, we provide new evidence concerning the purchasing power parity hypothesis. © Blackwell Publishing Ltd and the Department of Economics, University of Oxford, 2008.

New simple tests for panel cointegration

In this paper, two new simple residual-based panel data tests are proposed for the null of no cointegration. The tests are simple because they do not require any correction for the temporal dependencies of the data. Yet they are able to accommodate individual specific short-run dynamics, individual specific intercept and trend terms, and individual specific slope parameters. The limiting distributions of the tests are derived and are shown to be free of nuisance parameters. The Monte Carlo results in this paper suggest that the asymptotic results are borne out well even in very small samples. Copyright © Taylor & Francis, Inc.

Methods to prioritise adaptation options for iconic seabirds and marine mammals impacted by climate change

Climate change is already impacting a wide range of marine species around Australia. Australia has a large number of marine mammals and seabirds, particularly when Australian Antarctic and Southern Ocean species are included: 110 species of seabird and 52 species of marine mammal. These iconic species are protected throughout Australia and in some cases are recovering from previous anthropogenic impacts including harvest. The first tool we developed is a simple 'cost-benefit- risk' (CBR) screening tool to evaluate each scenario-specific adaptation option against a number of semi-quantitative attributes. Awareness and identification of potentially contested options would be useful to managers charged with implementing adaptation options. Following on from specific application, testing some of the adaptation options in limited field trials would be a useful next step, further building the experience of researchers and managers charged with securing the status of these iconic species in the future.

Can simple mobile phone applications provide reliable counts of respiratory rates in sick infants and children? An initial evaluation of three new applications

BACKGROUND: Respiratory rate is an important sign that is commonly either not recorded or recorded incorrectly. Mobile phone ownership is increasing even in resource-poor settings. Phone applications may improve the accuracy and ease of counting of respiratory rates. OBJECTIVES: The study assessed the reliability and initial users' impressions of four mobile phone respiratory timer approaches, compared to a 60-second count by the same participants. METHODS: Three mobile applications (applying four different counting approaches plus a standard 60-second count) were created using the Java Mobile Edition and tested on Nokia C1-01 phones. Apart from the 60-second timer application, the others included a counter based on the time for ten breaths, and three based on the time interval between breaths ('Once-per-Breath', in which the user presses for each breath and the application calculates the rate after 10 or 20 breaths, or after 60s). Nursing and physiotherapy students used the applications to count respiratory rates in a set of brief video recordings of children with different respiratory illnesses. Limits of agreement (compared to the same participant's standard 60-second count), intra-class correlation coefficients and standard errors of measurement were calculated to compare the reliability of the four approaches, and a usability questionnaire was completed by the participants. RESULTS: There was considerable variation in the counts, with large components of the variation related to the participants and the videos, as well as the methods. None of the methods was entirely reliable, with no limits of agreement better than -10 to +9 breaths/min. Some of the methods were superior to the others, with ICCs from 0.24 to 0.92. By ICC the Once-per-Breath 60-second count and the Once-per-Breath 20-breath count were the most consistent, better even than the 60-second count by the participants. The 10-breath approaches performed least well. Users' initial impressions were positive, with little difference between the applications found. CONCLUSIONS: This study provides evidence that applications running on simple phones can be used to count respiratory rates in children. The Once-per-Breath methods are the most reliable, outperforming the 60-second count. For children with raised respiratory rates the 20-breath version of the Once-per-Breath method is faster, so it is a more suitable option where health workers are under time pressure.

Early-life markers of atherosclerosis using aortic and carotid intima-media thickness: an assessment of methods to account for child size

Background.—Distinguishing pathological from physiological relationships between vessel size and aortic intima-media thickness (aIMT) is an important challenge, especially in growing children. We examined the relationship between childhood vessel diameter and aIMT and assessed common analytic approaches used to address this relationship.Methods.—We analyzed aIMT in two population-derived cohorts; 6-week-old infants and 19-year-olds. We simulated datasets in which we assumed a simple physiological relationship between vessel diameter and aIMT, and then superimposed possible pathological effects on aIMT; (a) intrauterine growth retardation, (b) macrosomia and (c) both intrauterine growth retardation and macrosomia. Using simulated datasets and cohorts, we evaluated analytic strategies including those in which the relationship between vessel diameter and aIMT was (a) ignored, (b) adjusted for by dividing aIMT by weight, or (c) adjusted for using varying regression techniques.Results.—aIMT was found to increase in proportion to vessel diameter in both cohorts (138 μm/mm at 6 weeks and 52 μm/mm at 19 years of age). Simply dividing aIMT by weight produced negative associations with weight across all datasets. By contrast, adjusting for vessel diameter as a covariate enabled accurate distinction of the direction of the association between aIMT and weight in all simulated datasets. These results were replicated in the cohort studies for both aIMT and carotid intima-media thickness.Conclusion.—There is a physiological relationship between vessel diameter and aIMT. Simply dividing aIMT by weight may lead to incorrect assumptions regarding the relationship between weight and aIMT. However, the physiological relationship is appropriately estimated by including vessel diameter as a covariate in regression.

Maximum power point tracking methods for PV systems

Maximum power point tracking (MPPT) is an important consideration in photovoltaic (PV) systems. These systems exhibit variable nonlinear current–voltage (I–V) and power–voltage (P–V) characteristics which vary with environmental conditions. The optimum operation of a PV system occurs when the system operates at the unique maximum power point (MPP) for the given environmental conditions. Key environmental conditions include the irradiance on the cell, temperature of the cell and any shading phenomenon. Shading can occur due to objects, dust or dirt and module mismatch arising from damage or manufacturing tolerances. These shading effects introduce further nonlinearity into the I–V and P–V characteristics of the system. An extensive variety of MPPT techniques has been proposed which vary from simple estimation techniques to advanced tracking techniques. In this chapter, the criteria for assessing the performance of MPPT methods are defined followed by a complete description and discussion of both techniques designed for uniform environmental conditions and those designed for nonuniform environmental conditions.

Simple techniques for a more inclusive curriculum

Students from low-socioeconomic status or non-English speaking backgrounds, or who have a disability, are Indigenous, or live in a remote area all generally score lower than average grades in Australian higher education. Deakin University’s Faculty of Arts & Education trialled a range of inclusive curriculum strategies in two units during 2015, with the aims of finding and embedding techniques that worked to improve learning outcomes of students in these groups, and at the same time building staff capacity in delivering inclusive curriculum. Staff from across academic and professional divisions collaborated to develop the techniques. This presentation outlines the techniques trialled, their varying impacts and critical success factors, as identified through quantitative and qualitative evaluation methods. Richly annotated readings, visual format seminar papers, and a formative peer assessment activity were found to be the most successful techniques. The presentation also describes briefly the staff capacity-building approach, based on activity systems theory.