Variations, trends and patterns of fish landings in large tropical reservoirs

Temporal variations of fish yields in four major reservoirs in Thailand (Ubolratana; Sirindhorn; Srinakarin; Vajiralongkorn) were investigated with the use of long-term fish landing data (≥20years). The long-term variations in fish yield, measured as the coefficient of variation of yearly yield, ranged mostly between 50% and 100%. For short-term variations, the means of the relative variation (85%) were larger than the absolute variation (63%). This finding indicates that short-term variations were inversely related to fish yield and that a higher uncertainty occurs when fish catches are low. The stocked exotic species exhibited higher variations than the indigenous species. The trend analyses indicated some species had sharply declined fish landings, while some species were quite stable (i.e. reservoir-adapted species). Stocked species tended to increase in relatively shallow reservoirs, compared to the deep reservoir. Fish landing data for each reservoir were patternized, using the self-organizing map, indicating temporal trends of chronological order. The differences among clusters in each reservoir were with respect to the weight of each species in the fish landings in each year, and temporal changes in species composition in the reservoirs, which would primarily be attributed to the environmental changes followed by anthropogenic pressures. The mean trophic level (τ) fluctuated, resulting from changes in species composition and weight of fish landing, as well as fish stocking programmes.

Fine-scale spatial and temporal variations in diets of the pipefish Stigmatopora nigra within seagrass patches

Diets of the pipefish Stigmatopora nigra were analysed to determine if food availability was causing S. nigra to distribute according to habitat edge effects. Gut analysis found little difference in the diets of S. nigra at the edge and interior of seagrass patches, regardless of time of day or season. Fish diets did, however, vary with seagrass density: S. nigra in denser seagrass consumed more harpacticoid copepods and fewer planktonic copepods. The lack of difference in prey eaten by S. nigra at the edge and interior of patches suggests either that food was not determining S. nigra distribution patterns within patches or that differences in fish densities across patches meant that relative fish–prey densities were similar at edge and interior positions. Alternatively, any edge effects in diet might be masked by gradients in seagrass structure.

Enterprise systems for innovation in products and processes : beyond operational efficiency

It has been widely accepted now in industry and academia that Enterprise Systems (ES) can create value for adopting organizations by enabling operational efficiency. However, given the enormous investments they warrant, the potential of such systems to deliver more than improving operations is emerging as a popular area of investigation. This paper reports a research-in-progress that proposes innovation as a means of creating business value with Enterprise Systems. The primary contribution of this paper is a process model that proposes that Enterprise Systems can enable innovation - in products and processes, and supports it with empirical evidence using three case studies. The intention is to test this model further with more case studies and a survey.

Interspecific variations in the gastrointestinal microbiota in penguins

Despite the enormous amount of data available on the importance of the gastrointestinal (GI) microbiota in vertebrate (especially mammals), information on the GI microbiota of seabirds remains incomplete. As with many seabirds, penguins have a unique digestive physiology that enables them to store large reserves of adipose tissue, protein, and lipids. This study used quantitative real-time polymerase chain reaction (qPCR) and 16S rRNA gene pyrosequencing to characterize the interspecific variations of the GI microbiota of four penguin species: the king, gentoo, macaroni, and little penguin. The qPCR results indicated that there were significant differences in the abundance of the major phyla Firmicutes, Bacteroides, Actinobacteria, and Proteobacteria. A total of 132,340, 18,336, 6324, and 4826 near full-length 16S rRNA gene sequences were amplified from fecal samples collected from king, gentoo, macaroni, and little penguins, respectively. A total of 13 phyla were identified with Firmicutes, Bacteroidetes, Proteobacteria, and Fusobacteria dominating the composition; however, there were major differences in the relative abundance of the phyla. In addition, this study documented the presence of known human pathogens, such as Campylobacter, Helicobacter, Prevotella, Veillonella, Erysipelotrichaceae, Neisseria, and Mycoplasma. However, their role in disease in penguins remains unknown. To our knowledge, this is the first study to provide an in-depth investigation of the GI microbiota of penguins.

Propensity score matching and variations on the balancing test

Balancing tests are diagnostics designed for use with propensity score methods, a widely used non-experimental approach in the evaluation literature. Such tests provide useful information on whether plausible counterfactuals have been created. Currently, multiple balancing tests exist in the literature but it is unclear which is the most useful. This article highlights the poor size properties of commonly employed balancing tests and attempts to shed some light on the link between the results of balancing tests and bias of the evaluation estimator. The simulation results suggest that in scenarios where the conditional independence assumption holds, a permutation version of the balancing test described in Dehejia and Wahba (Rev Econ Stat 84:151–161, 2002) can be useful in applied study. The proposed test has good size properties. In addition, the test appears to have good power for detecting a misspecification in the link function and some power for detecting an omission of relevant non-linear terms involving variables that are included at a lower order.

Temperature variations at nano-scale level in phase transformed nanocrystalline NiTi shape memory alloys adjacent to graphene layers

The detection and control of the temperature variation at the nano-scale level of thermo-mechanical materials during a compression process have been challenging issues. In this paper, an empirical method is proposed to predict the temperature at the nano-scale level during the solid-state phase transition phenomenon in NiTi shape memory alloys. Isothermal data was used as a reference to determine the temperature change at different loading rates. The temperature of the phase transformed zone underneath the tip increased by _3 to 40 _C as the loading rate increased. The temperature approached a constant with further increase in indentation depth. A few layers of graphene were used to enhance the cooling process at different loading rates. Due to the presence of graphene layers the temperature beneath the tip decreased by a further _3 to 10 _C depending on the loading rate. Compared with highly polished NiTi, deeper indentation depths were also observed during the solidstate phase transition, especially at the rate dependent zones. Larger superelastic deformations confirmed that the latent heat transfer through the deposited graphene layers allowed a larger phase transition volume and, therefore, more stress relaxation and penetration depth.

Neighborhood and individual socio-economic variations in the contribution of occupational physical activity to total physical activity

Background: There is an inverse relationship between individual socio-economic status (SES) and amount of occupational physical activity. The role of the socio-economic environment is, however, less clear. This study examined the independent influences of neighborhood and individual SES on absolute and relative amount of occupational physical activity. It also examined the moderating effects of neighborhood SES on the relationship between individual SES and occupational physical activity.

Methods: Employees (n = 1236) resident in high or low SES neighborhoods were assessed on socio-demographic factors, including educational attainment and household income, and physical activity.

Results: Neighborhood SES and individual SES were independently inversely related to absolute and relative amount of occupational physical activity. Significant interactions between neighborhood SES and level of educational attainment in the contribution of total and vigorous occupational physical activity to total physical activity were found.

Conclusions: Neighborhood SES can function as a moderator in the relationship between individual SES and occupational physical activity.