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Background Variation (background + variation)
Selected AbstractsStaff Activity in Supported Housing ServicesJOURNAL OF APPLIED RESEARCH IN INTELLECTUAL DISABILITIES, Issue 4 2002David Felce Background Variation in staff performance between small community housing services indicates the need for research on the factors which predict high-quality care. Methods The associations between service sector, staffing levels, staff characteristics, internal organization or working practices, non-institutional milieu, and staff activity and the nature and extent of staff attention to residents were explored in a study of 10 statutory, 10 voluntary and nine private sector community housing schemes. Results There were few significant differences between sectors after differences in resident abilities were taken into account. Higher staff to resident ratios predicted greater resident receipt of attention and assistance but also a lower proportion of time during which each member of staff was directly concerned with residents. A greater range in resident ability predicted lower resident receipt of attention and assistance. A higher proportion of qualified staff was not shown to be a positive attribute but greater prior experience was associated with staff spending more time directly concerned with residents, less time doing ,other' activity and residents receiving more assistance. Measures of the internal organization and non-institutional milieu of the settings were not strongly related to staff activity. Conclusions The findings are consistent with previous research that there are diminishing marginal returns associated with increasing staff. Size of residence was unimportant. Links between service organization and staff performance require further research but retaining experienced staff appears to be important. As resident receipt of attention and assistance was unrelated to their adaptive behaviour level, there is a need to find ways to ensure that staff support matches the needs of residents better. [source] Productivity of American robins exposed to polychlorinated biphenyls, Housatonic River, Massachusetts, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2003Miranda H. Henning Abstract American robins (Turdus migratorius) breeding in the Housatonic River (MA, USA) watershed were studied in the field in 2001 to determine whether productivity was adversely affected by exposure to polychlorinated biphenyls (PCBs), as would be suggested by extrapolation from laboratory studies on other avian species. The study involved identifying nests within the Housatonic River floodplain (target area) and in reference areas beyond foraging distance of the floodplain, monitoring clutch size and number hatched and fledged, collecting eggs and nestlings for analysis for PCBs, and testing for differences in productivity between populations. One hundred and six active robin nests were monitored. Although concentrations of PCBs in target specimens were more than two orders of magnitude greater than in reference specimens, the only statistically significant differences in productivity were inconsistent with an exposure-related effect. First-generation productivity of exposed robins was within the range of natural background variation. Bioequivalence tests confirmed that first-generation productivity was statistically and biologically equivalent in target and reference robins. These findings contrast with extrapolations from laboratory studies of other avian species. [source] Effects of sand sedimentation on the macroinvertebrate fauna of lowland streams: are the effects consistent?FRESHWATER BIOLOGY, Issue 1 2006BARBARA J. DOWNES Summary 1. In lowland streams sand sedimentation can produce sand slugs: very slow moving, discrete volumes of sand that are created episodically. Hypothetically, such sedimentation causes losses of habitat and fauna but little is known about the effects of sand slugs. In south-eastern Australia sand slugs are widespread, especially in streams with granitic catchments. 2. This study in north-central Victoria was centred on three streams that rise in the Strathbogie Ranges and flow out onto lowland plains, where they contain sand slugs. Below the sand slugs, the streams are slow-flowing ,chains of ponds' with a clay streambed. To correct for potential upstream-downstream confounding of comparisons, two unsanded, nearby streams were included as potential controls. Habitat measurements and faunal samples were taken in Spring 1998, from three sites in the sand slug and three sites in the clay-bed, downstream sections of each impacted stream, as well as from three sites in commensurate upstream and downstream sections of the control streams. 3. The sand-slugged sections had significantly higher velocities, shallower depths and less coarse woody debris than the unsanded downstream sections. Macroinvertebrate taxon richness and abundance showed some significant differences between the sand and clay sections compared with commensurate up- and downstream locations in the control streams. Effects were not uniform, however. In Castle Creek there were no significant differences between the sand and clay sections, in Pranjip-Ninemile Creek taxon richness and abundances were higher in sand than in the clay sections, whereas in Creightons Creek the ,expected' results of lower taxon richness and abundance in the sand were found. 4. Of the 40 most common taxa, only eight provided a clear signal related to sand and, of these, one (Slavina sp.) occurred only in the sand slugs, whereas the other seven had significantly higher numbers in the clay sections. Of these taxa, three were ostracods, three were chironomids and one was a tubificid oligochaete, all taxa that live in detritus-rich environments. Overall faunal composition did not show a clear distinction though, between sandy and clay sites. The sand slug community of Creightons Creek was very different from the other communities in all of the streams. There were clear differences in community composition between the sand-affected and the control streams, even for downstream, clay sections, suggesting they cannot act as controls for the impacted sections of the sand-slugged streams. 5. Differences between streams within categories (particularly between sand-slugged streams) and between sites in the same section of stream accounted for most of the variability in species richness and the abundances of each of the 40 most common taxa. That finding was repeated when data were examined at the family level, for both numbers of families per sample and collated lists of families occurring across sites. These results strongly suggest that the effects of sedimentation by sand slugs do not overwhelm background variation in macroinvertebrate density and diversity. Overall the results suggest that many taxa may respond individually, and that there is much variation between sand-affected streams even over relatively small (approximately <10 km) spatial scales. [source] Wavelet analysis applied to removing non-constant, varying spectroscopic background in multivariate calibrationJOURNAL OF CHEMOMETRICS, Issue 5 2002Hu-Wei Tan Abstract Multiresolution, the ability to separate signals according to frequency, is one of the main advantages offered by the wavelet transform. However, the coarsening of resolution associated with this method may be problematic in some applications. The ,wavelet prism' (WP) method proposed here can split the signal into different frequency components, which retain the original resolution of the signal. In conjunction with a maximum information gain criterion developed here, this new method can be used to judge and remove the low-frequency non-constant background variation reasonably and automatically. In this paper the theory and background concerning this wavelet baseline correction method are introduced. The method is successfully applied to simulated and real near-infrared (NIR) spectral data to deal with non-constant background for multivariate calibration. Its performance compares favorably with the current signal correction methods for background removal. The new method appears to be an efficient method for removal of non-constant, varying spectroscopic background, leading to a simpler and more parsimonious multivariate linear model. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||