Impact of long-range correlations on trend detection in total ozone

Total ozone trends are typically studied using linear regression models that assume a first-order autoregression of the residuals [so-called AR(1) models]. We consider total ozone time series over 60°S–60°N from 1979 to 2005 and show that most latitude bands exhibit long-range correlated (LRC) behavior, meaning that ozone autocorrelation functions decay by a power law rather than exponentially as in AR(1). At such latitudes the uncertainties of total ozone trends are greater than those obtained from AR(1) models and the expected time required to detect ozone recovery correspondingly longer. We find no evidence of LRC behavior in southern middle-and high-subpolar latitudes (45°–60°S), where the long-term ozone decline attributable to anthropogenic chlorine is the greatest. We thus confirm an earlier prediction based on an AR(1) analysis that this region (especially the highest latitudes, and especially the South Atlantic) is the optimal location for the detection of ozone recovery, with a statistically significant ozone increase attributable to chlorine likely to be detectable by the end of the next decade. In northern middle and high latitudes, on the other hand, there is clear evidence of LRC behavior. This increases the uncertainties on the long-term trend attributable to anthropogenic chlorine by about a factor of 1.5 and lengthens the expected time to detect ozone recovery by a similar amount (from ∼2030 to ∼2045). If the long-term changes in ozone are instead fit by a piecewise-linear trend rather than by stratospheric chlorine loading, then the strong decrease of northern middle- and high-latitude ozone during the first half of the 1990s and its subsequent increase in the second half of the 1990s projects more strongly on the trend and makes a smaller contribution to the noise. This both increases the trend and weakens the LRC behavior at these latitudes, to the extent that ozone recovery (according to this model, and in the sense of a statistically significant ozone increase) is already on the verge of being detected. The implications of this rather controversial interpretation are discussed

On the statistical modeling of persistence in total ozone anomalies

Geophysical time series sometimes exhibit serial correlations that are stronger than can be captured by the commonly used first‐order autoregressive model. In this study we demonstrate that a power law statistical model serves as a useful upper bound for the persistence of total ozone anomalies on monthly to interannual timescales. Such a model is usually characterized by the Hurst exponent. We show that the estimation of the Hurst exponent in time series of total ozone is sensitive to various choices made in the statistical analysis, especially whether and how the deterministic (including periodic) signals are filtered from the time series, and the frequency range over which the estimation is made. In particular, care must be taken to ensure that the estimate of the Hurst exponent accurately represents the low‐frequency limit of the spectrum, which is the part that is relevant to long‐term correlations and the uncertainty of estimated trends. Otherwise, spurious results can be obtained. Based on this analysis, and using an updated equivalent effective stratospheric chlorine (EESC) function, we predict that an increase in total ozone attributable to EESC should be detectable at the 95% confidence level by 2015 at the latest in southern midlatitudes, and by 2020–2025 at the latest over 30°–45°N, with the time to detection increasing rapidly with latitude north of this range

The adoption of low-cost low head drip irrigation in small-scale farms in Kenya

Population growth and development will increase the demands on water resources in Africa, and hence there is a need for agriculture to use water efficiently. Drip irrigation is widely promoted for water saving at the farm level. Moreover, it is easily adaptable to small-scale farming common in Africa. The use of low-cost drip irrigation, especially the low-cost medium head (LCMH) drip system, is growing rapidly in some Asian countries. However, the uptake of low-cost drip irrigation in general has been slow in Kenya, which has scarce water for irrigation. Using the theory of the adoption and diffusion of innovation, this research aimed to identify the factors affecting the rate of adoption and continued use of low-cost low head (LCLH) drip irrigation in Kenya. Following a review of experiences of low-cost drip irrigation from India and sub-Saharan Africa, primary information was obtained using informal interviews in a two-phase survey. A total of eighty-six respondents were interviewed in the two phases. Phase 1 examined the factors influencing the adoption of LCLH drip irrigation. The key respondents in phase 1 were irrigation farmers (drip and non-drip), government officials, irrigation industry representatives, and staff of non¬governmental organisations (NGOs). Phase 2 examined the factors affecting discontinuation of LCLH drip irrigation. In phase 2 only LCLH drip irrigation farmers and those who had discontinued using it were interviewed While the low-cost medium head drip irrigation was the dominant irrigation in India, the low-cost low head drip irrigation, gravity fed and in a kit form, was found to be the most common system on smallholder farms in Kenya. The results showed that for the rate of appropriate low-cost drip irrigation uptake to increase in Kenya, it was important to remove political and institutional inhibiting factors dominant during the implementation stages of the innovation-decision process. It was necessary for farmers to have a need to save irrigation water, reliable irrigation water resources, effective water user organisations, efficient marketing facilities, efficient technical support services, relevant cultural background, and good security for the kit. The LCLH drip irrigation kit appeared to have more maintenance problems than the alternative irrigation methods. Furthermore, government policies and extension services as well as irrigation industry efforts appeared limited. It appeared that the technology would most likely be adopted where farmers have a reliable but limited (in volume) water supply. In some situations, the LCLH drip technology, and particularly the smaller (bucket) kits, did not appear to be appropriate and should not be promoted. For other conditions, recommendations were made for helping to overcome the problems identified in the study. The Rogers innovation-decision model was shown to lack sufficient consideration of external factors. A revised model was proposed to suit the conditions of small-scale irrigation technology adoption in less developed countries.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Specialist nursing and community support for the carers of people with dementia living at home: an evidence synthesis.

Specialist nurses are one way of providing support for family carers of people with dementia, but relatively little is known about what these roles achieve, or if they are more effective than roles that do not require a clinical qualification. The aim of this review was to synthesise the literature on the scope and effectiveness of specialist nurses, known as Admiral Nurses, and set this evidence in the context of other community-based initiatives to support family carers of people with dementia. We undertook a systematic review of the literature relating to the scope and effectiveness of Admiral Nurses and a review of reviews of interventions to support the family carers of people with dementia. To identify studies, we searched electronic databases, undertook lateral searches and contacted experts. Searches were undertaken in November 2012. Results are reported narratively with key themes relating to Admiral Nurses identified using thematic synthesis. We included 33 items relating to Admiral Nurses (10 classified as research) and 11 reviews evaluating community-based support for carers of people with dementia. There has been little work to evaluate specific interventions provided by Admiral Nurses, but three overarching thematic categories were identified: (i) relational support, (ii) co-ordinating and personalising support and (iii) challenges and threats to the provision of services by Admiral Nurses. There was an absence of clearly articulated goals and service delivery was subject to needs of the host organisation and the local area. The reviews of community-based support for carers of people with dementia included 155 studies but, in general, evidence that interventions reduced caregiver depression or burden was weak, although psychosocial and educational interventions may reduce depression in carers. Community support for carers of people with dementia, such as that provided by Admiral Nurses, is valued by family carers, but the impact of such initiatives is not clearly established

Can the intake of antiparasitic secondary metabolites explain the low prevalence of hemoparasites among wild Psittaciformes?

Background: Parasites can exert selection pressure on their hosts through effects on survival, on reproductive success, on sexually selected ornament, with important ecological and evolutionary consequences, such as changes in population viability. Consequently, hemoparasites have become the focus of recent avian studies. Infection varies significantly among taxa. Various factors might explain the differences in infection among taxa, including habitat, climate, host density, the presence of vectors, life history and immune defence. Feeding behaviour can also be relevant both through increased exposure to vectors and consumption of secondary metabolites with preventative or therapeutic effects that can reduce parasite load. However, the latter has been little investigated. Psittaciformes (parrots and cockatoos) are a good model to investigate these topics, as they are known to use biological control against ectoparasites and to feed on toxic food. We investigated the presence of avian malaria parasites (Plasmodium), intracellular haemosporidians (Haemoproteus, Leucocytozoon), unicellular flagellate protozoans (Trypanosoma) and microfilariae in 19 Psittaciformes species from a range of habitats in the Indo-Malayan, Australasian and Neotropical regions. We gathered additional data on hemoparasites in wild Psittaciformes from the literature. We considered factors that may control the presence of hemoparasites in the Psittaciformes, compiling information on diet, habitat, and climate. Furthermore, we investigated the role of diet in providing antiparasitic secondary metabolites that could be used as self-medication to reduce parasite load. Results: We found hemoparasites in only two of 19 species sampled. Among them, all species that consume at least one food item known for its secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, were free from hemoparasites. In contrast, the infected parrots do not consume food items with antimalarial or even general antiparasitic properties. We found that the two infected species in this study consumed omnivorous diets. When we combined our data with data from studies previously investigating blood parasites in wild parrots, the positive relationship between omnivorous diets and hemoparasite infestation was confirmed. Individuals from open habitats were less infected than those from forests. Conclusions: The consumption of food items known for their secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, as well as the higher proportion of infected species among omnivorous parrots, could explain the low prevalence of hemoparasites reported in many vertebrates

Tropospheric Ozone Assessment Report: Tropospheric ozone from 1877 to 2016, observed levels, trends and uncertainties

From the earliest observations of ozone in the lower atmosphere in the 19th century, both measurement methods and the portion of the globe observed have evolved and changed. These methods have different uncertainties and biases, and the data records differ with respect to coverage (space and time), information content, and representativeness. In this study, various ozone measurement methods and ozone datasets are reviewed and selected for inclusion in the historical record of background ozone levels, based on relationship of the measurement technique to the modern UV absorption standard, absence of interfering pollutants, representativeness of the well-mixed boundary layer and expert judgement of their credibility. There are significant uncertainties with the 19th and early 20th-century measurements related to interference of other gases. Spectroscopic methods applied before 1960 have likely underestimated ozone by as much as 11% at the surface and by about 24% in the free troposphere, due to the use of differing ozone absorption coefficients. There is no unambiguous evidence in the measurement record back to 1896 that typical mid-latitude background surface ozone values were below about 20 nmol mol–1, but there is robust evidence for increases in the temperate and polar regions of the northern hemisphere of 30–70%, with large uncertainty, between the period of historic observations, 1896–1975, and the modern period (1990–2014). Independent historical observations from balloons and aircraft indicate similar changes in the free troposphere. Changes in the southern hemisphere are much less. Regional representativeness of the available observations remains a potential source of large errors, which are difficult to quantify

An adaptive annual rhythm in the sex of first pigeon eggs

When the reproductive value of male and female offspring varies differentially, parents are predicted to adjust the sex ratio of their offspring to maximize their fitness (Trivers and Willard, Science 179:90–92, 1973). Two factors have been repeatedly linked to skews in avian offspring sex ratio. First, laying date can affect offspring sex ratio when the sexes differ in age of first reproduction, such that the more slowly maturing sex is overproduced early in the season. Second, position of the egg in the laying sequence of a clutch may affect sex ratio bias since manipulating the sex of the first eggs may be least costly to the mother. We studied both factors in two non-domesticated pigeon species. Both the Wood pigeon (Columba palumbus) and the Rock pigeon (Columba livia) have long breeding seasons and lay two-egg clutches. In the field, we determined the sex of Wood pigeon nestlings. In Rock pigeons, housed in captivity outdoors, we determined embryo sex after 3 days of incubation. On the basis of their sex-specific age of first reproduction, we predicted that males, maturing at older age than females, should be produced in majority early and females later in the year. This was confirmed for both species. The bias was restricted to first eggs. Rock pigeons produced clutches throughout the year and show that the sex of the first egg followed an annual cycle. To our knowledge, this study presents the first evidence of a full annual rhythm in adaptive sex allocation in birds. We suggest that this reflects an endogenous seasonal program in primary sex ratio controlled by a preovulatory mechanism