Action of a finishing product in the improvement of the ultraviolet protection provided by modal and modal sun fabrics: Modelisation of the effect

The ultraviolet protection factor of a fabric is a quantitative measurement of the effectiveness of the fabric to protect the human skin against ultraviolet radiation. The protection provided by uncoloured cellulosic fabrics is, in general, too low, but can be improved by the finishing treatment with UV-absorbers. In the present paper Modal and Modal Sun fabrics with different compactness, and hence with different initial Ultraviolet Protection Factor values, are treated with several concentrations of an UV-absorber, according to a predefined experimental plan. The influence of each variable as well as their interaction on the response ultraviolet protection factor is analysed and a statistical model for predictions is proposed.     

A Comparison of MER::LUX Whole Cell Biosensors And Moss, A Bioindicator, For Estimating Mercury Pollution

A sensor responsive to Hg²⁺ (pDL20) was constructed by fusing part of a narrow spectrum mer operon, including its regulatory elements, to promoterless lux genes. This was compared with another mer::lux fusion (pRB28) in order to estimate the available Hg in moss, a conventional bioindicator used for surveying Hg pollution in terrestrial environments. Hg(II) was measured as the relative luminescence unit (RLU) emitted by E. coli cells carrying either pRB28 or pDL20. The linearity ranges of standard curves were measured by spiking HgCl₂ at different nanomole levels in a phosphate buffered solution (PBS). The level of correlation between RLU and spiked HgCl₂ depended on the incubation time of E. coli cells: the correlation factors (R ²) of the regression lines were highly significant only after 150 min of incubation. pDL20 detected Hg(II) concentrations in the linear range between 0.05 nM and 0.5 nM and was approximately 27 times more sensitive than pRB28. The latter was less sensitive and showed a different range of linearity, from 20 nM to 200 nM. Measurements of bioavailable Hg were performed in buffered solutions leached from moss. Concentrations of Hg(II) were determined by external standard addition of HgCl₂. pDL20 was found to be more reliable than pRB28 in the estimation of very low concentrations of bioavailable Hg (II). Both sensors were unable to determine Hg(0) emitted by geothermal activities.     

Precipitation-dependent source–sink dynamics in a spatially-structured population of an outbreaking caterpillar

Context

Patch-based population models predominately focus on factors that affect regional processes namely, patch size and connectivity, as the primary drivers explaining patch occupancy. This trend persists despite the recognition that patch quality can strongly influence population demography at the local scale. The quality of patches is often temporally variable and influenced by abiotic conditions. However, few studies have explicitly investigated how climatic variables influence the spatial and temporal dynamics of spatially-structured populations either directly or indirectly through changes in patch quality.

Objectives

Using a 10-year census of a spatially-structured population of an outbreaking caterpillar, we determined the relative importance of patch quality (determined demographically), connectivity, precipitation, and their interactive effects on patch abundance, occupancy, colonization, and extinction.

Methods

We generated a series of statistical models and performed comparisons using Akaike’s information criterion. We subsequently used likelihood ratio tests to determine the influence of each parameter on model fit.

Results

Patch quality and precipitation were the strongest predictors of the observed dynamics. We found that the dynamics of the spatially-structured population of Arctia virginalis were strongly influenced by precipitation: all patches had a higher probability of occupancy, contained higher abundances of caterpillars, and experienced fewer extinctions following wet winters compared to years following droughts.

Conclusion

These findings suggest that precipitation may act to influence the strength of heterogeneity of patch quality. This work demonstrates that patch-based models that do not include local and climatic factors may produce poor predictions under future climatic regimes.