Computability of the Radon-Nikodym derivative

We study the computational content of the Radon-Nokodym theorem from measure theory in the framework of the representation approach to computable analysis. We define computable measurable spaces and canonical representations of the measures and the integrable functions on such spaces. For functions f,g on represented sets, f is W-reducible to g if f can be computed by applying the function g at most once. Let RN be the Radon-Nikodym operator on the space under consideration and let EC be the non-computable operator mapping every enumeration of a set of natural numbers to its characteristic function. We prove that for every computable measurable space, RN is W-reducible to EC, and we construct a computable measurable space for which EC is W-reducible to RN

Air-exposure behavior: a restricted or a common conduct among intertidal hermit crabs?

A new behavior related to shell care was recently reported for the intertidal hermit crab Clibanarius erythropus (Latreille, 1818) in the Gulf of Cádiz (southwestern Europe). It also has been observed in other species of the diogenid genera Clibanarius Dana, 1952, and Calcinus Dana, 1951, however, it has not been described as an active behavior. In the present study, intertidal hermit crabs from different species and localities were sampled to assess if air-exposure is a shell cleaning behavior restricted to some species of intertidal hermit crabs or if it is a more generalized behavior among species inhabiting intertidal habitats. The results revealed that air-exposure is an active behavior in species of Clibanarius and Calcinus, since we observed it also in Clibanarius albidigitus Nobili, 1901, and Calcinus obscurus Stimpson, 1859, from the Pacific coast of Costa Rica, although not in other intertidal species studied by us. We found interspecific differences in tolerance to physical stress of emerged hermit crabs. This air-exposure tolerance can be interpreted as a physiological adaptation to desiccation stress and is also related to the shell type they inhabit. Also, we provide additional features and details of the air-exposure behavior, combining observations of the first description in 2015 with our new field observations.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR)UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biologí

Blowfly strike and the skin-fleece microenvironment of sheep

Blowfly strike or cutaneous myiasis is currently one of the major problems confronting the sheep industry in Australia. This thesis was undertaken to study blowfly strike, especially that occurring on the body of the sheep. Emphasis was placed on examining the interaction between sheep and blowflies and the role of the skin and fleece microenvironment in predisposing sheep to body strike. Long-term field studies were conducted on four Department of Agriculture Research Stations over three years with the aim of investigating the sheep-blowfly problem under field conditions. The results, based primarily on the data collected from Mount Barker Research Station (MtBRS), demonstrated that the field incidence of body strike was sporadic and that it occurred less frequently than breech strike. An analysis of the data failed to demonstrate a significant relationship between the occurrence of body strike and breech strike. Dermatophilosis was also found to be the most important of the skin and fleece conditions predisposing sheep to body strike. Samples collected from struck sheep confirmed that Ludlia cupvina (Wiedemann), the Australian sheep blowfly, was the most important of the primary blowfly species involved in fly-strike on sheep. CalViphova albifvontalis Malloch, the Western Australian brown blowfly, was also found to be an important primary species striking sheep at MtBRS. An investigation of the sheep-blowfly interaction in the field demonstrated that the majority of blowfly strike was recorded during the autumn and spring months each year. From the relationship between the relative abundance of primary blowflies and species involved in strike it was demonstrated that the presence of L. cupvina in the blowfly traps was probably sufficient indication that blowfly strike could occur. L. cuprina was shown to be present and presumably capable of striking throughout most months of the year except when the mean daily maximum temperature in any month (Tm.max) fell below a critical level (range 15 to 17°C). However C. albifvontalis, which was detected irrespective of Tm.max , throughout the entire year was only active in strike when present in relatively high numbers. An examination of the climatic factors associated with outbreaks of body strike demonstrated that the number of body strikes was dependent on both Tmax and the occurrence of rainfall in the week preceding strike. Of the two climatic factors rainfall was the most important. As a measurement of the lifetime susceptibility of an animal to body strike, attempts were made to derive a value for the repeatability of this condition. Unfortunately the low incidence of body strike prevented the derivation of a realistic estimate. As an alternative, the repeatability of dermatophilosis and fleece rot abnormalities shown to predispose animals to body strike was investigated. Even with this approach it was possible to derive a meaningful value only for the repeatability of fleece rot (0.26). To obviate the problems encountered in studying blowfly strike in the field, investigations were undertaken to simulate field fly wave conditions in the laboratory. Techniques were developed for the exposure of sheep artificially infected with Dermatophilus congolensis, to laboratory-reared L. ouprina blowflies in a controlled environment. The results from the first laboratory experiment demonstrated that gravid L. ouprina clearly preferred wet areas to dry areas of fleece on sheep. The inability of the blowflies to differentiate between the adjoining wet dermatophilosis-affected areas and the control areas of fleece, highlighted the need to specially separate test areas on experimental sheep. In a subsequent laboratory experiment wet dermatophilosis lesions were shown to be more attractive to gravid L. cuprina than wet control areas. The wet dermatophilosis lesions were also found to provide sufficient protein for the development of L. cuprina larvae to the second instar stage. As a consequence of the laboratory studies, a field study was conducted to relate these findings back to the field situation. The subsequent field study confirmed that dermatophilosis was the most important skin and fleece condition predisposing sheep to body strike. The bacteriological examination of sites adjoining the struck areas demonstrated that it was not always possible to isolate the bacteria associated with each skin and fleece condition visually recorded at each site. The approach adopted in this thesis of combining field observations with laboratory studies has led to the refinement of a hypothesis describing the interrelation of sheep, blowflies and climate as well as the role of bacteria and protein in both oviposition and the development of strike. It has also resulted in the identification of dermatophilosis as an important condition predisposing sheep to body strike in the field and allowed the subsequent study of this association under controlled conditions

Three regionalised analyses of a time-series of annual pasture production for southwest Western Australia

A thirteen year time-series (1994 to 2006) of gross annual pasture production (GAPP; representing both pasture and crop) was created for the Mediterranean-climate area in the southwest of Western Australia (SWWA) using a light-use efficiency model, incorporating NOAA-AVHRR and NASA- MODIS images in combination with climate data. Trends across the GAPP time-series were quantified by aggregating pixels to spatial regions (called a partition, unit, or spatial support) so that the effects of local spatial noise were minimized. We compared the GAPP analysis using the three spatial partitioning schemes (precipitation zones, Interim Biogeographic Regionalisation for Australia (IBRA) eco-regions, and Statistical Local Areas), and showed that the aggregation unit's size & shape impacted on the analysis. Our results demonstrate trends in GAPP that may be indicative of broader trends in climate change for the SWWA

Combining spectral information aggregated to the paddock scale with knowledge of on-farm practices will enhance remote sensing methods for intensively managed dairy pastures

No abstract availabl

Analysis of a time series of annual pasture production in south-west Western Australia

NO abstract availabl

Satellite Remote sensing feasibility of measuring pasture growth rate and pasture biomass in Southern Victorian dairy pastures: Phase III

No abstract availabl

The spectral response of pastures in an intensively managed dairy system

All grazing-based industries require information on their feed resources in order to manage them optimally. Gathering this information through traditional methods for measuring pasture biomass is time-consuming and error-prone, resulting in increased interest in remotely-sensed methods. Remote sensing used to monitor feed resources in farming systems differs from remote sensing of systems such as forestry because of how the time-scale of management practices impacts on the growth rate and accumulation patterns of biomass. Also, in operational systems, designed for near real-time delivery to end-users of quantitative pasture measurements, we are restricted to the commercially available broad-band high-resolution sensors. The goal of this paper is to understand how remotely-sensed observations of pastures in an intensively managed dairy system change in relation to intensive management practices, so that better image analysis and ground-validation methods can be developed for measuring and monitoring such systems. At two dates in the growing season we examined high-resolution (SPOT-5 and Ikonos) images of an intensively managed perennial dairy farm in Victoria (Australia). We showed that the observed spectral response in the images varied with the length of time since the paddock was grazed, consistent with the re-growth of pastures post-grazing. The operational remote sensing of pastures is often restricted by the range of spectral bands that are available on broad-band sensors. However, these results suggest that when choosing a vegetation index for intensively managed dairy pastures it should incorporate the short-wave infrared (SWIR) band to improve observations of recently grazed pastures and tune analyses based on the spectral response

The effect of grazing on the remote-sensing of pastures in a rotationally-grazed dairy system

[No abstract available

Pastures from Space™: Transforming Australian agricultural industries through satellite remote-sensing and geospatial technology

No abstract availabl