A predictive model of avian natal dispersal distance provides prior information for investigating response to landscape change

1. Informative Bayesian priors can improve the precision of estimates in ecological studies or estimate parameters for which little or no information is available. While Bayesian analyses are becoming more popular in ecology, the use of strongly informative priors remains rare, perhaps because examples of informative priors are not readily available in the published literature.
2. Dispersal distance is an important ecological parameter, but is difficult to measure and estimates are scarce. General models that provide informative prior estimates of dispersal distances will therefore be valuable.
3. Using a world-wide data set on birds, we develop a predictive model of median natal dispersal distance that includes body mass, wingspan, sex and feeding guild. This model predicts median dispersal distance well when using the fitted data and an independent test data set, explaining up to 53% of the variation.
4. Using this model, we predict a priori estimates of median dispersal distance for 57 woodland-dependent bird species in northern Victoria, Australia. These estimates are then used to investigate the relationship between dispersal ability and vulnerability to landscape-scale changes in habitat cover and fragmentation.
5. We find evidence that woodland bird species with poor predicted dispersal ability are more vulnerable to habitat fragmentation than those species with longer predicted dispersal distances, thus improving the understanding of this important phenomenon.
6. The value of constructing informative priors from existing information is also demonstrated. When used as informative priors for four example species, predicted dispersal distances reduced the 95% credible intervals of posterior estimates of dispersal distance by 8-19%. Further, should we have wished to collect information on avian dispersal distances and relate it to species' responses to habitat loss and fragmentation, data from 221 individuals across 57 species would have been required to obtain estimates with the same precision as those provided by the general model.

A predictive model of avian natal dispersal distance provides prior information for investigating response to landscape change

1. Informative Bayesian priors can improve the precision of estimates in ecological studies or estimate parameters for which little or no information is available. While Bayesian analyses are becoming more popular in ecology, the use of strongly informative priors remains rare, perhaps because examples of informative priors are not readily available in the published literature.

2. Dispersal distance is an important ecological parameter, but is difficult to measure and estimates are scarce. General models that provide informative prior estimates of dispersal distances will therefore be valuable.

3. Using a world-wide data set on birds, we develop a predictive model of median natal dispersal distance that includes body mass, wingspan, sex and feeding guild. This model predicts median dispersal distance well when using the fitted data and an independent test data set, explaining up to 53% of the variation.

4. Using this model, we predict a priori estimates of median dispersal distance for 57 woodland-dependent bird species in northern Victoria, Australia. These estimates are then used to investigate the relationship between dispersal ability and vulnerability to landscape-scale changes in habitat cover and fragmentation.

5. We find evidence that woodland bird species with poor predicted dispersal ability are more vulnerable to habitat fragmentation than those species with longer predicted dispersal distances, thus improving the understanding of this important phenomenon.

6. The value of constructing informative priors from existing information is also demonstrated. When used as informative priors for four example species, predicted dispersal distances reduced the 95% credible intervals of posterior estimates of dispersal distance by 8-19%. Further, should we have wished to collect information on avian dispersal distances and relate it to species' responses to habitat loss and fragmentation, data from 221 individuals across 57 species would have been required to obtain estimates with the same precision as those provided by the general model.

Identification of surface heterogeneity effects in cyclic voltammograms derived from analysis of an individually addressable gold array electrode

Voltammetric behavior at gold electrodes in aqueous media is known to be strongly dependent on electrode polishing and history. In this study, an electrode array consisting of 100 nominally identical and individually addressable gold disks electrodes, each with a radius of 127 µm, has been fabricated. The ability to analyze both individual electrode and total array performance enables microscopic aspects of the overall voltammetric response arising from variable levels of inhomogeneity in each electrode to be identified. The array configuration was initially employed with the reversible and hence relatively surface insensitive [Ru(NH₃)₆]^3+/2+ reaction and then with the more highly surface sensitive quasi-reversible [Fe(CN)₆]^3−/4− process. In both these cases, the reactants and products are solution soluble and, at a scan rate of 50 mV s⁻¹, each electrode in the array is assumed to behave independently, since no evidence of overlapping of the diffusion layers was detected. As would be expected, the variability of the individual electrodesʼ responses was significantly larger than found for the summed electrode behavior. In the case of cytochrome c voltammetry at a 4,4′-dipyridyl disulfide modified electrode, a far greater dependence on electrode history and electrode heterogeneity was detected. In this case, voltammograms derived from individual electrodes in the gold array electrode exhibit shape variations ranging from peak to sigmoidal. However, again the total response was always found to be well-defined. This voltammetry is consistent with a microscopic model of heterogeneity where some parts of each chemically modified electrode surface are electroactive while other parts are less active. The findings are consistent with the common existence of electrode heterogeneity in cyclic voltammetric responses at gold electrodes, that are normally difficult to detect, but fundamentally important, as electrode nonuniformity can give rise to subtle forms of kinetic and other forms of dispersion.

Treatment response for acute depression is not associated with number of previous episodes: lack of evidence for a clinical staging model for major depressive disorder

Mental illness has been observed to follow a neuroprogressive course, commencing with prodrome, then onset, recurrence and finally chronic illness. In bipolar disorder and schizophrenia responsiveness to treatment mirrors these stages of illness progression, with greater response to treatment in the earlier stages of illness and greater treatment resistance in chronic late stage illness.

Using data from 5627 participants in 15 controlled trials of duloxetine, comparator arm (paroxetine, venlafaxine, escitalopram) or placebo for the treatment of an acute depressive episode, the relationship between treatment response and number of previous depressive episodes was determined. Data was dichotomised for comparisons between participants who had >3 previous episodes (n=1697) or ≤3 previous episodes (n=3930), and additionally for no previous episodes (n=1381) or at least one previous episode (n=4246). Analyses were conducted by study arm for each clinical trial, and results were then pooled.

There was no significant difference between treatment response and number of previous depressive episodes. This unexpected finding suggests that treatments to reduce symptoms of depression during acute illness do not lose efficacy for patients with a longer history of illness.

A Response to Critique of the Refreeze Step in Lewin’s Model of Organizational Change from the Viewpoint of Organizational Behavior

Problem Statement
This paper responds to criticism of Kurt Lewin’s three step model of organizational change in increasingly turbulent environments. It explores whether the refreeze step of Kurt Lewin’s notable three step model is still applicable to organizational change processes in the age of globalisation and digitalisation.

Method
Literature review and critical analysis of applied examples are used to provide an overview of Kurt Lewin’s three-step change model. Authors’ observations and reflections are integrated in the discussion. The changing contemporary environment and the implications for the refreeze step of Lewin’s model are accordingly discussed.

Conclusions
The paper concludes that a balance of stability and movement; of discrete and emergent change; is the reality for today’s organizations, and forms the touchstone for Lewin’s formulation of change theories. Alignment is observed between notions of desired equilibrium in Lewin’s model and the contemporary underpinnings of sustainability. Technology and the modern pace of organizational change are also factors to consider. There has hence been an adaptation of his theoretical heritage that is current and sufficiently robust to withstand the criticisms of the refreeze stage.

Role of surface properties of titanium alloys on osteoblasts response

This thesis examined the behavior of osteoblast cells in response to material surfaces. Cell behavior at the cellular and molecular level on Ti and two Ti alloys (TiZr and TiNb) in response to their material surface properties were evaluated at different stages of cell-material interactions namely adhesion, proliferation and differentiation.

Determining the sensitivity of the Antarctic amphipod Orchomenella pinguides to metals using a joint model of survival response to exposure concentration and duration

Developing water quality guidelines for Antarctic marine environments requires understanding the sensitivity of local biota to contaminant exposure. Antarctic invertebrates have shown slower contaminant responses in previous experiments compared to temperate and tropical species in standard toxicity tests. Consequently, test methods which take into account environmental conditions and biological characteristics of cold climate species need to be developed. This study investigated the effects of five metals on the survival of a common Antarctic amphipod, Orchomenella pinguides. Multiple observations assessing mortality to metal exposure were made over the 30 days exposure period. Traditional toxicity tests with quantal data sets are analysed using methods such as maximum likelihood regression (probit analysis) and Spearman–Kärber which treat individual time period endpoints independently. A new statistical model was developed to integrate the time-series concentration–response data obtained in this study. Grouped survival data were modelled using a generalized additive mixed model (GAMM) which incorporates all the data obtained from multiple observation times to derive time integrated point estimates. The sensitivity of the amphipod, O. pinguides, to metals increased with increasing exposure time. Response times varied for different metals with amphipods responding faster to copper than to cadmium, lead or zinc. As indicated by 30 days lethal concentration (LC50) estimates, copper was the most toxic metal (31 µg/L), followed by cadmium (168 µg/L), lead (256 µg/L) and zinc (822 µg/L). Nickel exposure (up to 1.12 mg/L) did not affect amphipod survival. Using longer exposure durations and utilising the GAMM model provides an improved methodology for assessing sensitivities of slow responding Antarctic marine invertebrates to contaminants.