Study design synopsis: Battle in the stable: Bayesianism versus Frequentism

Frequentism dominates scientific practice although Bayesianism may provide an alternative, especially when analysing data from complex, high-dimensional models. The key differences between Bayesianism and Frequentism are highlighted in the introduction. Next, I review the different stages of Bayesian statistical reasoning in a research setting, explain the key concepts and illustrate them with toy examples taken in equine veterinary medicine. An extension to more complex models (Bayes network) is introduced and guidelines are offered as a conclusion.     

DISPERSAL PATTERN OF INJECTATE FOLLOWING CT‐GUIDED PERINEURAL INFILTRATION IN THE CANINE THORACOLUMBAR SPINE: A CADAVER STUDY

An increasing proportion of canine patients are presented with chronic thoracolumbar back pain and without compressive spinal lesions. In humans, spinal perineural infiltrations have been reported to have a favorable effect on pain control. The purpose of this prospective cadaver study was to describe the dispersal pattern of injectate following CT‐guided spinal perineural infiltration in the canine thoracolumbar region. Seven fresh canine cadavers were first scanned using multislice CT and then CT‐guided spinal perineural infiltration was performed at 42 sites from T13/L1 to L6/L7. The injectate for each site was a mixture of new methylene blue and iodinated contrast medium. Immediately following CT‐guided injection, cadavers were frozen, cut, and dissected macro‐ and mesoscopically (using a magnifying glass) to identify anatomic structures that were infiltrated. In the majority of sites (64.3%), complete epidural and hypaxial staining of spinal nerve components (including the spinal ganglion, trunk, and ventral branch) was successfully achieved. However, no (11.9%) or unpredictable staining (9.5%) of nervous tissue occurred in some sites despite careful CT guidance and the application of relatively large volumes of injectate. Optimal results were achieved when the needle tip was positioned periforaminally ventral to the cranial contour of the cranial articular process. Findings from this ex vivo study indicated that CT‐guided spinal perineural infiltration is feasible for testing in the canine thoracolumbar region and that successful nerve tissue infiltration would likely occur in the majority of sites. Future in vivo studies are needed to determine the safety and efficacy of this technique.     

The role of fire in forest dynamics in Daxinganling region

Recent fire statistics and preliminary fire history data suggest that fire has been historically responsible for maintaining the vegetative communities up to present in Daxinganling region. Forest types, and even tree species, arc dependent on the degree of fire intensity, fire size, depth of burn and fire frequency. Selected samples of larch, pine, birch and spruce forest were studied in terms of species composition as determined by fire frequency which mainly depends on topography and site conditions. Intervals between fires range between 6 and 170 years.     

Beliefs of South Africans regarding food and cardiovascular health

OBJECTIVES: To investigate the beliefs of South African metropolitan adults regarding the importance of influencing cardiovascular health by eating certain food types, and to compare these beliefs between different race, living standards, age and gender groups. DESIGN: Randomised cross-sectional study. Trained fieldworkers administered questionnaires by conducting face-to-face interviews with consumers. SUBJECTS: Two thousand South Africans (16 years and older) were randomly selected from metropolitan areas in South Africa. The data were weighted to be representative of the total South African metropolitan population (N = 10 695 000) based on gender, age and race distribution. RESULTS: The majority (94 %) of the population indicated that it is important to influence cardiovascular risk-related health issues by eating certain food types, especially the higher LSM (Living Standard Measure) groups within the different race groups. Weight loss was considered the least important (61 % indicated that it is important) compared with cholesterol lowering (80 %), blood pressure (89 %), diabetes (86 %) and healthy blood vessels (89 %). In the higher LSM groups (7-10) higher proportions of respondents agreed than in the lower LSM groups (2 and 3). No differences were seen in responses between different gender, race and age groups.Conclusions and recommendationsThis study shows that the metropolitan South African adult population considers the influence on cardiovascular health by eating certain food types to be important. However, modifying weight loss by eating certain food types was considered less important.     

Collembolan grazing affects the growth strategy of the cord-forming fungus Hypholoma fasciculare

Mycelia of cord-forming fungi show remarkable patterns of reallocation of biomass and nutrients indicating an important role of these, often extensive, organisms in the spatial translocation of energy and nutrients in forest soils. Despite the rich tradition of interaction studies between soil microarthropods and fungi, the spatial implications of these interactions, due to the potential growth responses of the fungi and to the translocation of energy and nutrients within the mycelial network, have been largely ignored. In this paper we analyse fungal growth responses in two-dimensional model systems composed of compressed soil, the cord-forming fungus Hypholoma fasciculare and three fungivorous Collembolan species. We hypothesised that (i) the highly co-ordinated nature of cord-forming fungi would lead to growth responses following collembolan grazing, and that, (ii) such changes are dependent on grazing intensity, and (iii) changes are dependent on the species grazing. Mycelial extent and hyphal cover decreased with increasing grazing density; at highest grazing density also the fractal dimension of the mycelial border decreased, indicating a less branched foraging front due to the regression of fine hyphae and the development of mycelial cords. Effects differed greatly between collembolan species although they exerted comparable grazing pressure (the smaller species were added in larger numbers according to their allometric size-metabolic rate relationships): while grazing by Folsomia candida resulted in less mycelial extension and hyphal cover, these variables were not affected when Proisotoma minuta and Hypogastrura cf. tullbergi grazed. The effects of a species mix suggested an additive effect of the component species. This shows that fungal mycelia may suffer from damage caused by few but large collembolans, affecting extension as well as coverage of the mycelium, but that fungi may compensate for the biomass loss caused by more but slightly smaller collembolans. In about 20% of the model systems H. fasciculare switched from a growth pattern with a broad contiguous foraging front and uniform growth in all directions to a pattern with fast growing sectors while other sectors stopped growth completely. The switch occurred in grazed systems exclusively; thus we interpret this observation as a fugitive response and as a strategy for quickly escaping from places where grazing pressure is experienced.     

Fox sightings in a city are related to certain land use classes and sociodemographics: results from a citizen science project

Background

Red foxes (Vulpes vulpes L.) have become successful inhabitants of urban areas in recent years. However, our knowledge about the occurrence, distribution and association with land uses of these urban foxes is poor, partly because many favoured habitats are on private properties and therefore hardly accessible to scientists. We assumed that citizen science, i.e. the involvement of the public, could enable researchers to bridge this information gap. We analysed 1179 fox sightings in the city of Vienna, Austria reported via citizen science projects to examine relationships between foxes and the surrounding land use classes as well as sociodemographic parameters.

Results

Conditional probabilities of encountering foxes were substantially higher in gardens, areas with a low building density, parks or squares as compared to agricultural areas, industrial areas or forests. Generalized linear model analyses showed that sociodemographic parameters such as education levels, district area, population density and average household income additionally improved the predictability of fox sightings.

Conclusions

Reports of fox sightings by citizen scientists might help to support the establishment of wildlife management in cities. Additionally, these data could be used to address public health issues in relation with red foxes as they can carry zoonoses that are also dangerous to humans.

     

Breeding objectives and the relative importance of traits in plant and animal breeding: a comparative review

Breeding objectives always involve consideration of multiple traits, even in situations where output of a single trait is dominant. We review literature dealing with formal definition of breeding objectives. Involvement of farmers in the process of setting up breeding objectives is also considered. In the optimal selection index, the relative importance of a trait is scaled by its economic value, derived as marginal profit related to a change in expression of defined size. Normative approaches to derive economic values use partial derivatives of a profit equation with respect to the traits involved or model the bio-economic system with various techniques. The theory is well developed and includes consideration of non-linear profit functions and traits with an intermediate optimum. It is frequently applied in animal breeding. In dairy cattle breeding, a major change of focus from traits related to output (i.e., milk yield) to traits related to cost of input (health, fertility, feed efficiency) has taken place recently. Plant breeders find the concept of deriving relative economic weights of traits difficult to apply and often replace the optimal index by restricted or desired gains indices. A change of paradigms similar to that in cattle breeding seems advisable. Participatory approaches to evaluate the relative importance of traits are more frequently applied in plant breeding than in animal breeding. We review two studies, dealing with methods of acquiring information about selection criteria of farmers planting maize in the Ethiopian highlands and of pastoralists keeping cattle in Uganda, in detail.