Significances of differences between slopes: An upgrade for replicated time series

In some ecology subjects the slope of the line fit between x and y variables is the focus of concern. Such is the case of self-thinning theory, developed for plant demography and later verified also occurring in algae and animals. Different slopes identify statistical populations subject to different conditions. Therefore, it is fundamental that a test is able to identify honestly significant differences between slopes. The most used tested for the overlap of the 95% confidence intervals of the bootstrapped slopes. However, Vieira and Creed (2013) demonstrated it to possess weak theoretical grounds having proposed a permutation methods alternative. Unfortunately, both were fallible upon small sample sizes and/or large data scatter. Data about self-thinning, as well as other subjects, often comes in replicated time series enabling upgrading the test algorithm to randomize sampling units only within the respective time frame. This was added to the previous software, increasing outstandingly the capacity of the permutation test in identifying both true and false differences between slopes

Estimating significances of differences between slopes: A new methodology and software

Determining the significance of slope differences is a common requirement in studies of self-thinning, ontogeny and sexual dimorphism, among others. This has long been carried out testing for the overlap of the bootstrapped 95% confidence intervals of the slopes. However, the numerical random re-sampling with repetition favours the occurrence of re-combinations yielding largely diverging slopes, widening the confidence intervals and thus increasing the chances of overlooking significant differences. To overcome this problem a permutation test simulating the null hypothesis of no differences between slopes is proposed. This new methodology, when applied both to artificial and factual data, showed an enhanced ability to differentiate slopes

Consideration of selflessness and self-interest in outsourcing decisions

Purpose – The paper aims to discuss the need to balance selflessness and self-interest issues in outsourcing decisions. This discussion is timely given the tensions that currently exist between those who want off-shore outsourcing to continue as a means for increasing international trade, and those who only want to conduct business on-shore. Design/methodology/approach – A conceptual approach has been taken in this paper in order to highlight key considerations for ethical decision-making with respect to off-shore outsourcing. Findings – Considerations of selflessness and self-interest are embedded in outsourcing decisions. It is recommended that a balance between making profits and fulfilling social responsibilities is required, ideally, at each stage of decision-making. Hence, managers should think critically about the reasons behind off-shore outsourcing decisions, the process of arriving at decisions, and the impact of their decisions on stakeholders. Research limitations/implications – This is a conceptual paper and further empirical data to validate the stages of decision-making framework are required. Practical implications – Failure to take into account the selflessness and self-interest outcomes of off-shore outsourcing could potentially off-set strategic gains by leading to negative media publicity for a company. Social implications – Ethical considerations as part of outsourcing decisions should result in a transparent, fair and more humane working environment for both the host and the home country representatives involved in the process. Originality/value – This paper presents an original framework of selflessness and self-interest considerations when making off-shore outsourcing decisions. Both Eastern and Western business perspectives have been incorporated as part of the decision-making framework

Evolutionary Responses of Marine Organisms to Urbanized Seascapes

Many of the world\u27s major cities are located in coastal zones, resulting in urban and industrial impacts on adjacent marine ecosystems. These pressures, which include pollutants, sewage, runoff and debris, temperature increases, hardened shorelines/structures, and light and acoustic pollution, have resulted in new evolutionary landscapes for coastal marine organisms. Marine environmental changes influenced by urbanization may create new selective regimes or may influence neutral evolution via impacts on gene flow or partitioning of genetic diversity across seascapes. While some urban selective pressures, such as hardened surfaces, are similar to those experienced by terrestrial species, others, such as oxidative stress, are specific to aquatic environments. Moreover, spatial and temporal scales of evolutionary responses may differ in the ocean due to the spatial extent of selective pressures and greater capacity for dispersal/gene flow. Here, we present a conceptual framework and synthesis of current research on evolutionary responses of marine organisms to urban pressures. We review urban impacts on genetic diversity and gene flow and examine evidence that marine species are adapting, or are predicted to adapt, to urbanization over rapid evolutionary time frames. Our findings indicate that in the majority of studies, urban stressors are correlated with reduced genetic diversity. Genetic structure is often increased in urbanized settings, but artificial structures can also act as stepping stones for some hard‐surface specialists, promoting range expansion. Most evidence for rapid adaptation to urban stressors comes from studies of heritable tolerance to pollutants in a relatively small number of species; however, the majority of marine ecotoxicology studies do not test directly for heritability. Finally, we highlight current gaps in our understanding of evolutionary processes in marine urban environments and present a framework for future research to address these gaps

Bed-slope-related diffusion of an erodible hump

In certain conditions, the bed slope has a substantial influence on sediment transport rates and hence morphological evolution. Approaches to account for such influence usually suffer from a high degree of empiricism and/or mathematical complexity. We propose a bed slope related diffusivity parameter, derived from a morphodynamic model previously validated against empirical data for bedload transport on horizontal and steep sloping channels. The proposed diffusivity parameter is easy to include in a conventional morphodynamic model via the modification of a typical bedload formula originally developed for sediment transport in a nearly horizontal channel. A conventional model modified through this parameter proves to yield enhanced results in the case study of a submerged migrating sandbar, by avoiding the generation of unrealistic high-frequency oscillations in the bed profile, yet permitting the expected steepening of its downstream face with time. Other models derived for sloping channels do not satisfy the latter condition. It is also shownthat unre-alistic oscillations can be avoided through numerical means; however, their use should be interpreted carefully from a hydrodynamic and sedimentological viewpoint

The effect of age and font size on reading text on handheld computers

Though there have been many studies of computer based text reading, only a few have considered the small screens of handheld computers. This paper presents an investigation into the effect of varying font size between 2 and 16 point on reading text on a handheld computer. By using both older and younger participants the possible effects of age were examined. Reading speed and accuracy were measured and subjective views of participants recorded. Objective results showed that there was little difference in reading performance above 6 point, but subjective comments from participants showed a preference for sizes in the middle range. We therefore suggest, for reading tasks, that designers of interfaces for mobile computers provide fonts in the range of 8-12 point to maximize readability for the widest range of users

Focal cerebral ischemia in the TNFalpha-transgenic rat

<p>Abstract</p> <p>Background</p> <p>To determine if chronic elevation of the inflammatory cytokine, tumor necrosis factor-α (TNFα), will affect infarct volume or cortical perfusion after focal cerebral ischemia.</p> <p>Methods</p> <p>Transgenic (TNFα-Tg) rats overexpressing the murine TNFα gene in brain were prepared by injection of mouse DNA into rat oocytes. Brain levels of TNFα mRNA and protein were measured and compared between TNFα-Tg and non-transgenic (non-Tg) littermates. Mean infarct volume was calculated 24 hours or 7 days after one hour of reversible middle cerebral artery occlusion (MCAO). Cortical perfusion was monitored by laser-Doppler flowmetry (LDF) during MCAO. Cortical vascular density was quantified by stereology. Post-ischemic cell death was assessed by immunohistochemistry and regional measurement of caspase-3 activity or DNA fragmentation. Unpaired <it>t </it>tests or analysis of variance with post hoc tests were used for comparison of group means.</p> <p>Results</p> <p>In TNFα-Tg rat brain, the aggregate mouse and rat TNFα mRNA level was fourfold higher than in non-Tg littermates and the corresponding TNFα protein level was increased fivefold (p ≤ 0.01). Infarct volume was greater in TNFα-Tg rats than in non-Tg controls at 24 hours (p ≤ 0.05) and 7 days (p ≤ 0.01). Within the first 10 minutes of MCAO, cortical perfusion measured by LDF was reduced in TNFα-Tg rats (p ≤ 0.05). However, regional vascular density was equivalent between TNFα-Tg and non-Tg animals (p = NS). Neural cellular apoptosis was increased in transgenic animals as shown by elevated caspase-3 activity (p ≤ 0.05) and DNA fragmentation (p ≤ 0.001) at 24 hours.</p> <p>Conclusion</p> <p>Chronic elevation of TNFα protein in brain increases susceptibility to ischemic injury but has no effect on vascular density. TNFα-Tg animals are more susceptible to apoptotic cell death after MCAO than are non-Tg animals. We conclude that the TNFα-Tg rat is a valuable new tool for the study of cytokine-mediated ischemic brain injury.</p

A cost-effective method to quantify biological surface sediment reworking

We propose a simple and inexpensive method to determine the rate and pattern of surface sediment reworking by benthic organisms. Unlike many existing methods commonly used in bioturbation studies, which usually require sediment sampling, our approach is fully non-destructive and is well suited for investigating non-cohesive fine sediments in streams and rivers. Optical tracer (e.g., luminophores or coloured sand) disappearance or appearance is assessed through time based on optical quantification of surfaces occupied by tracers. Data are used to calculate surface sediment reworking (SSR) coefficients depicting bioturbation intensities. Using this method, we evaluated reworking activity of stream organisms (three benthic invertebrates and a fish) in laboratory microcosms mimicking pool habitats or directly in the field within arenas set in depositional zones. Our method was sensitive enough to measure SSR as low as 0.2 cm2.d-1, such as triggered by intermediate density (774 m-2) of Gammarus fossarum (Amphipoda) in microcosms. In contrast, complex invertebrate community in the field and a fish (Barbatula barabatula) in laboratory microcosms were found to yield to excessively high SSR (>60 cm2.d-1). Lastly, we suggest that images acquired during experiments can be used for qualitative evaluation of species-specific effects on sediment distribution