Bayesian classification of catchments using spatial data: a first step to improved modelling of catchment effects on stream ecological condition

A major challenge facing freshwater ecologists and managers is the development of models that link stream ecological condition to catchment scale effects, such as land use. Previous attempts to make such models have followed two general approaches. The bottom-up approach employs mechanistic models, which can quickly become too complex to be useful. The top-down approach employs empirical models derived from large data sets, and has often suffered from large amounts of unexplained variation in stream condition.

We believe that the lack of success of both modelling approaches may be at least partly explained by scientists considering too wide a breadth of catchment type. Thus, we believe that by stratifying large sets of catchments into groups of similar types prior to modelling, both types of models may be improved. This paper describes preliminary work using a Bayesian classification software package, ‘Autoclass’ (Cheeseman and Stutz 1996) to create classes of catchments within the Murray Darling Basin based on physiographic data.

Autoclass uses a model-based classification method that employs finite mixture modelling and trades off model fit versus complexity, leading to a parsimonious solution. The software provides information on the posterior probability that the classification is ‘correct’ and also probabilities for alternative classifications. The importance of each attribute in defining the individual classes is calculated and presented, assisting description of the classes. Each case is ‘assigned’ to a class based on membership probability, but the probability of membership of other classes is also provided. This feature deals very well with cases that do not fit neatly into a larger class. Lastly, Autoclass requires the user to specify the measurement error of continuous variables.

Catchments were derived from the Australian digital elevation model. Physiographic data werederived from national spatial data sets. There was very little information on measurement errors for the spatial data, and so a conservative error of 5% of data range was adopted for all continuous attributes. The incorporation of uncertainty into spatial data sets remains a research challenge.

The results of the classification were very encouraging. The software found nine classes of catchments in the Murray Darling Basin. The classes grouped together geographically, and followed altitude and latitude gradients, despite the fact that these variables were not included in the classification. Descriptions of the classes reveal very different physiographic environments, ranging from dry and flat catchments (i.e. lowlands), through to wet and hilly catchments (i.e. mountainous areas). Rainfall and slope were two important discriminators between classes. These two attributes, in particular, will affect the ways in which the stream interacts with the catchment, and can thus be expected to modify the effects of land use change on ecological condition. Thus, realistic models of the effects of land use change on streams would differ between the different types of catchments, and sound management practices will differ.

A small number of catchments were assigned to their primary class with relatively low probability. These catchments lie on the boundaries of groups of catchments, with the second most likely class being an adjacent group. The locations of these ‘uncertain’ catchments show that the Bayesian classification dealt well with cases that do not fit neatly into larger classes.

Although the results are intuitive, we cannot yet assess whether the classifications described in this paper would assist the modelling of catchment scale effects on stream ecological condition. It is most likely that catchment classification and modelling will be an iterative process, where the needs of the model are used to guide classification, and the results of classifications used to suggest further refinements to models.

One-step coating of fluoro-containing silica nanoparticles for universal generation of surface superhydrophobicity

Stable superhydrophobic surfaces with water contact angles over 170 degrees and sliding angles below 7 degrees were produced by simply coating a particulate silica sol solution of co-hydrolysed TEOS/fluorinated alkyl silane with NH₃^.H₂O on various substrates, including textile fabrics (e.g. polyester, wool and cotton), electrospun nanofibre mats, filter papers, glass slides, and silicon wafers.

The effects of a simplified tai-chi exercise program (STEP) on the physical health of older adults living in long-term care facilities : a single group design with multiple time points

Background
Studies support the positive effects that Tai Chi has on the physical health of older adults. However, many older adults residing in long-term care facilities feel too weak to practice traditional Tai Chi, and a more simplified style is preferred.
Objective
To test the effects of a newly-developed, Simplified Tai-Chi Exercise Program (STEP) on the physical health of older adults who resided in long-term care facilities.
Design
A single group design with multiple time points: three pre-tests, one month apart; four post-tests at one month, two months, three months, and six months after intervention started.
Settings
Two 300–400 bed veteran homes in Taiwan.
Participants
The 51 male older adults were recruited through convenience sampling, and 41 of them completed six-month study. Inclusion criteria included: (1) aged 65 and over; (2) no previous training in Tai Chi; (3) cognitively alert and had a score of at least eight on the Short Portable Mental Status Questionnaire; (4) able to walk without assistance; and (5) had a Barthel Index score of 61 or higher. Participants who had dementia, were wheel-chair bound, or had severe or acute cardiovascular, musculoskeletal, or pulmonary illnesses were excluded.
Methods
The STEP was implemented three times a week, 50 min per session for six months. The outcome measures included cardio-respiratory function, blood pressure, balance, hand-grip strength, lower body flexibility, and physical health actualization.
Results
A drop in systolic blood pressure (p=.017) and diastolic blood pressure (p<.001) was detected six months after intervention started. Increase in hand-grip strength from pre to post intervention was found (left hand: p<.001; right hand: p=.035). Participants also had better lower body flexibility after practicing STEP (p=.038).
Conclusions
Findings suggest that the STEP be incorporated as a floor activity in long-term care facilities to promote physical health of older adults.

A step toward a common measure of organizational fairness

The paper examines dimensions of organizational justice construct in a public sector context, utilizing an organizational justice measure developed and validated by Colquitt (2001). The present study substantiates the existing claims about the independence of interactional justice and the division of interactional justice into interpersonal and informational justice. The present investigation also contributes to the justice literature by providing evidence of a new factor, which is called procedural voice justice to reflect the possible association with the concept of voice effect. Although voice has been examined extensively in the justice research as an antecedent of procedural justice, little is known about if and how voice might integrate into procedural justice construct. The study proposes that future justice research further investigate dimensionality of organisational justice and aspire to developing a common measure of the justice construct.

Variable step-size LMS algorithm with a quotient form

An improved robust variable step-size least mean square (LMS) algorithm is developed in this paper. Unlike many existing approaches, we adjust the variable step-size using a quotient form of filtered versions of the quadratic error. The filtered estimates of the error are based on exponential windows, applying different decaying factors for the estimations in the numerator and denominator. The new algorithm, called more robust variable step-size (MRVSS), is able to reduce the sensitivity to the power of the measurement noise, and improve the steady-state performance for comparable transient behavior, with negligible increase in the computational cost. The mean convergence, the steady-state performance and the mean step-size behavior of the MRVSS algorithm are studied under a slow time-varying system model, which can be served as guidelines for the design of MRVSS algorithm in practical applications. Simulation results are demonstrated to corroborate the analytic results, and to compare MRVSS with the existing representative approaches. Superior properties of the MRVSS algorithm are indicated.

A class of modified variable step-size NLMS algorithms for system identification

This paper proposes a class of modified variable step-size normalized least mean square (VS NLMS) algorithms. The class of schemes are obtained from estimating the optimum step-size of NLMS that minimizes the mean square deviation (MSD). During the estimation, we consider the properties of the additive noise and the input excitation together. The developed class of VS NLMS algorithms have simple forms and give improved tradeoff of fast convergence rate and low misadjustment in system identification.

Mathematical power of special-needs pupils : an ICT-based dynamic assessment format to reveal weak pupils' learning potential

This paper reports a study aimed at revealing special-educational-needs pupils' learning potential by means of an ICT-based assessment including a dynamic visual tool that might help pupils when solving mathematics problems. The study focused on subtraction problems up to 100, which require 'borrowing'. These problems, in which the value of the ones-digit of the subtrahend is larger than the ones-digit of the minuend, are known as a serious difficulty for weak pupils in mathematics. Seven of such problems from a standardised test were placed in the ICT environment. Data were collected from two test conditions: the standardised written test format and the ICT version of the test items including the tool that provided pupils with a set of virtual manipulatives. The 37 pupils involved in the study were 8–12 years old and from two special-education schools in the Netherlands. Comparison of the performance scores in the two formats showed that an ICT-based assessment format, including a dynamic visual tool, can reveal weak pupils' learning potential and strategy use. The study also pointed out that 'partial-tool use', ie, not carrying out the complete subtraction operation with the tool, can provide sufficient support to find the correct answer.

Joint European masters awards in construction management and construction economics : a positive step for surveying education?

The Royal Institution of Chartered Surveyors (RICS) 5th European Conference in November 2004 focussed on enhancing collaboration at master's level in real estate education across Europe. In a context of increased global economic activity and increasing ties within the EU, there are benefits to business and to students in offering this type of educational provision. But is this paradigm true for construction economics (CE) and construction management (CM)? This paper examined the potential for collaboration and joint European awards in CM and CE. There is a political will for collaboration in HE based on economic drivers for the growth of the EU and changes are being implemented to enhance transparency and mobility for students. Professional bodies are expanding their European presence. Globalisation has resulted in greater opportunities for international real estate, and construction and there is growth in these sectors for practitioners. The difficulties with joint European collaboration are short course duration and the need to cover extensive subject matter. Other barriers are university structures, quality assurance procedures, costs and finances issues as well as IT, student services and support issues. The survey revealed that there are no RICS accredited CM / CE courses outside of the UK which inhibits collaboration. The sample was split in perceived demand for collaboration and the European focus within the courses is limited, as are field trips outside the UK. Student exchange on courses is rare. Generally there is a lag between the political will to greater student mobility and collaboration and the market, which is showing growth in multinational organisations and demand for pan European construction services and a professional body keen to deliver and support this growth. Within academia the barriers and current economic climate in HE preclude the widespread adoption of greater collaboration and development of joint awards, however this position may change.

Encouraging governments to enhance the happiness of their nation : Step 1: understand subjective wellbeing

This article considers the issue of facilitating policies that enhance population happiness. An impediment to such action is the failure of most policy makers to understand that subjective wellbeing can be measured and understood within the framework of science. Additionally, they fail to realize that enhancing the subjective wellbeing of populations enhances not only the functioning of individuals but that of the population as a whole. A framework for understanding calls on the Theory of Subjective Wellbeing Homeostasis and data from the Australian Unity Wellbeing Index. This Index has been used to monitor the subjective wellbeing of the Australian population over the 6-year period 2001–2006. The article begins by a description of the subjective wellbeing construct and the theory that it is homeostatically managed. The operation of homeostasis makes very determined predictions as to the kinds of relationships that should be found in association with various environmental challenges and resources. These predictions will be examined in the light of the data from our surveys and the benefits of population happiness will be discussed. Finally, consideration will be given as to and how such understanding may be conveyed to politicians, in order to assist the development of policies aimed at enhancing the level of happiness in society.

One-step purification and immobilization of his-tagged rhamnosidase for naringin hydrolysis

α-l-Rhamnosidase (EC 3.2.1.40) is an enzyme that catalyzes the cleavage of terminal rhamnoside groups from naringin to prunin and rhamnose. In this study, a His-tag was genetically attached to the rhamnosidase gene ramA from Clostridium stercorarium to facilitate its purification from Escherichia coli BL21 (DE3) cells containing the pET-21d/ramA plasmid. Immobilized metal-chelate affinity chromatography (IMAC) resulted in one-step purification of N-terminally His-tagged recombinant rhamnosidase (N-His-CsRamA) which was immobilized in Ca²⁺ alginate (3%) beads. The optimum pH levels of the free and immobilized recombinant rhamnosidase were found to be 6.0 and 7.5, and the optimum temperature 55 and 60 °C respectively. At 50 °C, the free enzyme was relatively stable and exhibited a less than 50% reduction in residual activity after 180 min of incubation. The free and immobilized enzymes achieved 76% and 67% hydrolysis of the naringin in Kinnow juice respectively. Immobilization of recombinant rhamnosidase enabled its reutilization up to 9 hydrolysis batches without an appreciable loss in activity. This result indicated that the His-tagged thermostable rhamnosidase could be prepared as described and may serve to illustrate an economical and commercially viable process for industrial application.