1,367 research outputs found
The Effect of Interviewer Experience, Attitudes, Personality and Skills on Respondent Co-operation with Face-to-Face Surveys
This paper examines the role of interviewers' experience, attitudes, personality traits and inter-personal skills in determining survey co-operation, conditional on contact. We take the perspective that these characteristics influence interviewers' behaviour and hence influence the doorstep interaction between interviewer and sample member. Previous studies of the association between doorstep behaviour and co-operation have not directly addressed the role of personality traits and inter-personal skills and most have been based on small samples of interviewers. We use a large sample of 842 face-to-face interviewers working for a major survey institute and analyse co-operation outcomes for over 100,000 cases contacted by those interviewers over a 13-month period. We find evidence of effects of experience, attitudes, personality traits and inter-personal skills on co-operation rates. Several of the effects of attitudes and inter-personal skills are explained by differences in experience, though some independent effects remain. The role of attitudes, personality and skills seems to be greatest for the least experienced interviewers
Common-path multimodal optical microscopy
We have developed a common-path multimodal optical microscopy system that is capable of using a single optical source and a single camera to image amplitude, phase, and fluorescence features of a biological specimen. This is achieved by varying either contrast enhancement filters at the Fourier plane and/or neutral density/fluorescence filters in front of the CCD camera. The feasibility of the technique is demonstrated by obtaining brightfield, fluorescence, phase-contrast, spatially filtered, brightfield + fluorescence, phase +fluorescence, and edge-enhanced+fluorescence images of the same Drosophila embryo without the need for image registration and fusion. This comprehensive microscope has the capability of providing both structural and functional information and may be used for applications such as studying live-cell dynamics and in high throughput microscopy and automated microscopy
Ecological indicators for abandoned mines, Phase 1: Review of the literature
Mine waters have been identified as a significant issue in the majority of Environment Agency draft River Basin Management Plans. They are one of the largest drivers for chemical pollution in the draft Impact Assessment for the Water Framework Directive (WFD), with significant failures of environmental quality standards (EQS) for metals (particularly Cd, Pb, Zn, Cu, Fe) in many rivers linked to abandoned mines. Existing EQS may be overprotective of aquatic life which may have adapted over centuries of exposure. This study forms part of a larger project to investigate the ecological impact of metals in rivers, to develop water quality targets (alternative objectives for the WFD) for aquatic ecosystems impacted by long-term mining pollution. The report reviews literature on EQS failures, metal effects on aquatic biota and effects of water chemistry, and uses this information to consider further work.
A preliminary assessment of water quality and biology data for 87 sites across Gwynedd and Ceredigion (Wales) shows that existing Environment Agency water quality and biology data could be used to establish statistical relations between chemical variables and metrics of ecological quality. Visual representation and preliminary statistical analyses show that invertebrate diversity declines with increasing zinc concentration. However, the situation is more complex because the effects of other metals are not readily apparent. Furthermore, pH and aluminium also affect streamwater invertebrates, making it difficult to tease out toxicity due to individual mine-derived metals.
The most characteristic feature of the plant communities of metal-impacted systems is a reduction in diversity, compared to that found in comparable unimpacted streams. Some species thrive in the presence of heavy metals, presumably because they are able to develop metal tolerance, whilst others consistently disappear. Effects are, however, confounded by water chemistry, particularly pH. Tolerant species are spread across a number of divisions of photosynthetic organisms, though green algae, diatoms and blue-green algae are usually most abundant, often thriving in the absence of competition and/or grazing. Current UK monitoring techniques focus on community composition and, whilst these provide a sampling and analytical framework for studies of metal impacts, the metrics are not sensitive to these impacts. There is scope for developing new metrics, based on community-level analyses and for looking at morphological variations common in some taxa at elevated metal concentrations. On the whole, community-based metrics are recommended, as these are easier to relate to ecological status definitions.
With respect to invertebrates and fish, metals affect individuals, population and communities but sensitivity varies among species, life stages, sexes, trophic groups and with body condition. Acclimation or adaptation may cause varying sensitivity even within species. Ecosystem-scale effects, for example on ecological function, are poorly understood. Effects vary between metals such as cadmium, copper, lead, chromium, zinc and nickel in order of decreasing toxicity. Aluminium is important in acidified headwaters. Biological effects depend on speciation, toxicity, availability, mixtures, complexation and exposure conditions, for example discharge (flow). Current water quality monitoring is unlikely to detect short-term episodic increases in metal concentrations or evaluate the bioavailability of elevated metal concentrations in sediments. These factors create uncertainty in detecting ecological impairment in metal-impacted ecosystems. Moreover, most widely used biological indicators for UK freshwaters were developed for other pressures and none distinguishes metal impacts from other causes of impairment. Key ecological needs for better regulation and management of metals in rivers include: i) models relating metal data to ecological data that better represent influences on metal toxicity; ii) biodiagnostic indices to reflect metal effects; iii) better methods to identify metal acclimation or adaptation among sensitive taxa; iv) better investigative procedures to isolate metal effects from other pressures.
Laboratory data on the effects of water chemistry on cationic metal toxicity and bioaccumulation show that a number of chemical parameters, particularly pH, dissolved organic carbon (DOC) and major cations (Na, Mg, K, Ca) exert a major influence on the toxicity and/or bioaccumulation of cationic metals. The biotic ligand model (BLM) provides a conceptual framework for understanding these water chemistry effects as a combination of the influence of chemical speciation, and metal uptake by organisms in competition with H+ and other cations. In some cases where the BLM cannot describe effects, empirical bioavailable models have been successfully used. Laboratory data on the effects of metal mixtures across different water chemistries are sparse, with implications for transferring understanding to mining-impacted sites in the field where mixture effects are likely.
The available field data, although relatively sparse, indicate that water chemistry influences metal effects on aquatic ecosystems. This occurs through complexation reactions, notably involving dissolved organic matter and metals such as Al, Cu and Pb. Secondly, because bioaccumulation and toxicity are partly governed by complexation reactions, competition effects among metals, and between metals and H+, give rise to dependences upon water chemistry. There is evidence that combinations of metals are active in the field; the main study conducted so far demonstrated the combined effects of Al and Zn, and suggested, less certainly, that Cu and H+ can also contribute. Chemical speciation is essential to interpret and predict observed effects in the field. Speciation results need to be combined with a model that relates free ion concentrations to toxic effect. Understanding the toxic effects of heavy metals derived from abandoned mines requires the simultaneous consideration of the acidity-related components Al and H+.
There are a number of reasons why organisms in waters affected by abandoned mines may experience different levels of metal toxicity than in the laboratory. This could lead to discrepancies between actual field behaviour and that predicted by EQS derived from laboratory experiments, as would be applied within the WFD. The main factors to consider are adaptation/acclimation, water chemistry, and the effects of combinations of metals. Secondary effects are metals in food, metals supplied by sediments, and variability in stream flows. Two of the most prominent factors, namely adaptation/ acclimation and bioavailability, could justify changes in EQS or the adoption of an alternative measure of toxic effects in the field. Given that abandoned mines are widespread in England and Wales, and the high cost of their remediation to meet proposed WFD EQS criteria, further research into the question is clearly justified.
Although ecological communities of mine-affected streamwaters might be over-protected by proposed WFD EQS, there are some conditions under which metals emanating from abandoned mines definitely exert toxic effects on biota. The main issue is therefore the reliable identification of chemical conditions that are unacceptable and comparison of those conditions with those predicted by WFD EQS. If significant differences can convincingly be demonstrated, the argument could be made for alternative standards for waters affected by abandoned mines. Therefore in our view, the immediate research priority is to improve the quantification of metal effects under field circumstances. Demonstration of dose-response relationships, based on metal mixtures and their chemical speciation, and the use of better biological tools to detect and diagnose community-level impairment, would provide the necessary scientific information
The effect of mode and context on survey results: analysis of data from the Health Survey for England 2006 and the Boost Survey for London.
BACKGROUND: Health-related data at local level could be provided by supplementing national health surveys with local boosts. Self-completion surveys are less costly than interviews, enabling larger samples to be achieved for a given cost. However, even when the same questions are asked with the same wording, responses to survey questions may vary by mode of data collection. These measurement differences need to be investigated further. METHODS: The Health Survey for England in London ('Core') and a London Boost survey ('Boost') used identical sampling strategies but different modes of data collection. Some data were collected by face-to-face interview in the Core and by self-completion in the Boost; other data were collected by self-completion questionnaire in both, but the context differed. Results were compared by mode of data collection using two approaches. The first examined differences in results that remained after adjusting the samples for differences in response. The second compared results after using propensity score matching to reduce any differences in sample composition. RESULTS: There were no significant differences between the two samples for prevalence of some variables including long-term illness, limiting long-term illness, current rates of smoking, whether participants drank alcohol, and how often they usually drank. However, there were a number of differences, some quite large, between some key measures including: general health, GHQ12 score, portions of fruit and vegetables consumed, levels of physical activity, and, to a lesser extent, smoking consumption, the number of alcohol units reported consumed on the heaviest day of drinking in the last week and perceived social support (among women only). CONCLUSION: Survey mode and context can both affect the responses given. The effect is largest for complex question modules but was also seen for identical self-completion questions. Some data collected by interview and self-completion can be safely combined
The burden and risk factors for adverse drug events in older patients - a prospective cross-sectional study
Objective: To determine the burden and risk factors for adverse drug events (ADEs) in older patients.
Design: A prospective cross-sectional study.
Methods: Patients (65 years and older) presenting to the tertiary Emergency Unit of Groote Schuur Hospital, Cape Town, between February and May 2005, were assessed for well established ADEs, as defined by the South African Medicines Formulary. Logistic regression models were fitted to determine drugs and other factors associated with the likelihood of developing ADEs.
Results: ADEs were identified in 104 of the 517 (20%) presentations. The most frequently involved drug classes were cardiovascular (34%), anticoagulant (27%), analgesic (19%) and antidiabetic (9%). Patients who developed ADEs were more likely to have five or more prescription drugs (p < 0.0001), more than three clinical problems (p = 0.001), require admission (p = 0.04), and report compliance with medication (p = 0.02) than those who did not. Drugs shown to independently confer increased risk of ADEs were angiotensin-converting enzyme inhibitors (RR = 2.6, 95% CI: 1.3 - 5.2, p = 0.009), non-steroidal anti-inflammatory drugs (RR = 4.1, 95% CI: 2.1 - 8.0, p < 0.0001) and warfarin (RR = 3.1, 95% CI: 1.6 - 6.3, p = 0.0014).
Conclusion: ADEs contribute significantly to the burden of elderly care in the Emergency Unit. In a setting such as ours, increased pill burden and certain drug classes are likely to result in increased risk of ADEs in the older population group.South African Medical Journal Vol. 96 (12) 2006: pp. 1255-125
The effect of ocean acidification on organic and inorganic speciation of trace metals
Rising concentrations of atmospheric carbon dioxide are causing acidification of the oceans. 20 This results in changes to the concentrations of key chemical species such as hydroxide, 21 carbonate and bicarbonate ions. These changes will affect the distribution of different forms 22 of trace metals. Using IPCC data for pCO2 and pH under four future emissions scenarios (to 23 the year 2100) we use a chemical speciation model to predict changes in the distribution of 24 organic and inorganic forms of trace metals. Under a scenario where emissions peak after 25 the year 2100, predicted free ion Al, Fe, Cu and Pb concentrations increase by factors of up 26 to approximately 21, 2.4, 1.5 and 2.0 respectively. Concentrations of organically complexed 27 metal typically have a lower sensitivity to ocean acidification induced changes. 28 Concentrations of organically-complexed Mn, Cu, Zn and Cd fall by up to 10%, while those 29 of organically-complexed Fe, Co and Ni rise by up to 14%. Although modest, these changes 30 may have significance for the biological availability of metals given the close adaptation of 31 marine microorganisms to their environment
Recommendations for the acute and long-term medical management of low-trauma hip fractures
Hip fractures are the most serious complication of osteoporosis and are associated with high morbidity and mortality. Generally, patients who sustain osteoporotic hip fractures are older adults who have a number of comorbiddiseases which predispose them to perioperative complications, disability and death. Furthermore, patients who survive a hip fracture are at higher risk of a subsequent fracture. The morbidity and mortality of hip fractures can be substantially reduced by a structured multidisciplinary approach to pre- and postoperative management. This review will focus on the epidemiology of hip fractures, predictors of mortality and the acute and long-term management of hip fractures
An analysis of mode effects using data from the Health Survey for England 2006 and the Boost Survey for London
The effect of mode and context on survey results: Analysis of data from the Health Survey for England 2006 and the Boost Survey for London
Background: Health-related data at local level could be provided by supplementing national health surveys with local boosts. Self-completion surveys are less costly than interviews, enabling larger samples to be achieved for a given cost. However, even when the same questions are asked with the same wording, responses to survey questions may vary by mode of data collection. These measurement differences need to be investigated further.Methods: The Health Survey for England in London ('Core') and a London Boost survey ('Boost') used identical sampling strategies but different modes of data collection. Some data were collected by face-to-face interview in the Core and by self-completion in the Boost; other data were collected by self-completion questionnaire in both, but the context differed.Results were compared by mode of data collection using two approaches. The first examined differences in results that remained after adjusting the samples for differences in response. The second compared results after using propensity score matching to reduce any differences in sample composition. Results: There were no significant differences between the two samples for prevalence of some variables including long-term illness, limiting long-term illness, current rates of smoking, whether participants drank alcohol, and how often they usually drank. However, there were a number of differences, some quite large, between some key measures including: general health, GHQ12 score, portions of fruit and vegetables consumed, levels of physical activity, and, to a lesser extent, smoking consumption, the number of alcohol units reported consumed on the heaviest day of drinking in the last week and perceived social support (among women only).Conclusion: Survey mode and context can both affect the responses given. The effect is largest for complex question modules but was also seen for identical self-completion questions. Some data collected by interview and self-completion can be safely combined
Verification of the H2O Linelists with Theoretically Developed Tools
Two basic rules (i.e., the pair identity and the smooth variation rules) resulting from the properties of the energy levels and wave functions of H2O states govern how the spectroscopic parameters vary with the H2O lines within the individually defined groups of lines. With these rules, for those lines involving high j states in the same groups, variations of all their spectroscopic parameters (i.e., the transition frequency, intensity, pressure broadened half-width, pressure-induced shift, and temperature exponent) can be well monitored. Thus, the rules can serve as simple and effective tools to screen the H2O spectroscopic data listed in the HITRAN database and verify the latter's accuracies. By checking violations of the rules occurring among the data within the individual groups, possible errors can be picked up and also possible missing lines in the linelist whose intensities are above the threshold can be identified. We have used these rules to check the accuracies of the spectroscopic parameters and the completeness of the linelists for several important H2O vibrational bands. Based on our results, the accuracy of the line frequencies in HITRAN 2008 is consistent. For the line intensity, we have found that there are a substantial number of lines whose intensity values are questionable. With respect to other parameters, many mistakes have been found. The above claims are consistent with a well known fact that values of these parameters in HITRAN contain larger uncertainties. Furthermore, supplements of the missing line list consisting of line assignments and positions can be developed from the screening results
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