12,732 research outputs found
Integrating research with NHS clinical practice: Unwelcome intrusion or constructive triangulation?
When embarking on research into the effectiveness of psychoanalytic psychotherapy in the NHS or the application of psychoanalytic principles, researchers come up against a number of hurdles: many clinicians still see empirical research as antithetical or disruptive to the practice of psychoanalytic psychotherapy; psychoanalytic psychotherapy has previously fared poorly in evidence-based policy guidelines and this can discourage ambition, and there are technical problems of research design, measurement and standardization. Nevertheless, in a political climate which stresses service evaluation, measurable outcomes and empirical evidence, psychoanalytic psychotherapy must participate to survive. There may be gains from conducting research beyond simply meeting the requirement to provide evidence of effectiveness. Research may be viewed by some clinicians as an unwelcome intruder but it may have the potential to offer triangulation, the perspective of the 'third', and so strengthen the foundations of clinical practice and the development of psychoanalytic thought
Do trophic subsidies affect the outcome of introductions of a non-native freshwater fish?
Understanding how environmental variables and human disturbances influence the outcomes of introductions of non-native freshwater fish is integral to their risk management. This can be complex in freshwater ecosystems that receive subsidies that increase food availability, as these may influence the outcome of introductions through promoting the survival, reproduction and establishment of the introduced propagules through increasing their access to food resources. We determined how natural and/or artificial trophic subsidies affected the reproduction and establishment of the introduced topmouth gudgeon (Pseudorasbora parva) in replicated pond mesocosms. The mesocosms all started with eight mature fish and were run for 100 days during their reproductive season. The subsidies consisted of natural terrestrial prey and/or fishmeal pellets (a common trophic subsidy that can be significant in systems that are used as sport fisheries or for aquaculture). After 100 days, fish in the natural subsidy ponds showed minimal growth and very low reproductive output. Analysis of δC and δN indicated that their progeny, 0+ fish produced in the ponds, exploited the terrestrial prey. By contrast, in ponds where pellets were added, mineral nutrient availability and primary production were significantly increased, and the mature fish fed mainly on the aquatic resources. The increased productivity of the ponds significantly increased fish growth and fitness, resulting in high numbers of 0+ individuals that did feed on the pellets. Thus, subsidies that can increase both primary production and food resources (such as pelletised fishmeal) can significantly influence the ability of colonists to establish a population rapidly. Management efforts to minimise the risk of introductions should thus consider the role of these types of allochthonous subsidies. © 2013 The Authors. Freshwater Biology published by John Wiley & Sons Ltd
The Metabolic Ecology of Tropical Amphibians Across an Elevational Gradient in the Andes of Southeastern Peru
Metabolism is a fundamental biological process that determines the rate at which organisms process energy and materials, and determines the availability of resources for growth, maintenance and reproduction. Metabolic rates scale across levels of organization from cells to whole organisms and affect population, community, and ecosystem processes. Anthropogenic climate change and other environmental changes are predicted to have major impacts on the energetics of organisms that will be mediated through metabolic physiology. Tropical ectotherms, such as amphibians, may be among the most vulnerable to metabolic impacts of climate change as a result of being ectothermic, having high thermal sensitivity, and living at relatively high temperatures (close to upper thermal tolerances). However, many predictions use universal metabolic scaling relationships derived predominantly from temperate taxa in modeling efforts, and there has been little work to determine whether such relationships also characterize the metabolic rates of tropical ectotherms.
I use field-based respirometry to examine the metabolic physiology of tropical amphibians along an elevational gradient on the eastern slope of the Andes in southeastern Peru. I describe variation in metabolic physiology of tropical amphibians and how it relates to patterns of phylogeny, ecology, and environment. I demonstrate that there are consistent diel rhythms in resting metabolic rates that lead to significant differences between day and night, and that the timing of circadian rhythms differs among families. I confirm that there are strong phylogenetic signals in the patterns of resting and active metabolic rates of tropical amphibians and illustrate that accounting for phylogenetic differences is important for analyses of interspecific comparisons of metabolic physiology. I discuss how variation in metabolic physiology may relate to ecological characteristics, and how the combination of physiology and ecology may determine ecological strategies and vulnerability to metabolic impacts of climate change. Consideration of the variation in amphibian metabolism is essential to make accurate predictions of metabolic impacts of climate change, to inform conservation and management decisions, and to understand the integrative biology of tropical amphibian
A weighted configuration model and inhomogeneous epidemics
A random graph model with prescribed degree distribution and degree dependent
edge weights is introduced. Each vertex is independently equipped with a random
number of half-edges and each half-edge is assigned an integer valued weight
according to a distribution that is allowed to depend on the degree of its
vertex. Half-edges with the same weight are then paired randomly to create
edges. An expression for the threshold for the appearance of a giant component
in the resulting graph is derived using results on multi-type branching
processes. The same technique also gives an expression for the basic
reproduction number for an epidemic on the graph where the probability that a
certain edge is used for transmission is a function of the edge weight. It is
demonstrated that, if vertices with large degree tend to have large (small)
weights on their edges and if the transmission probability increases with the
edge weight, then it is easier (harder) for the epidemic to take off compared
to a randomized epidemic with the same degree and weight distribution. A recipe
for calculating the probability of a large outbreak in the epidemic and the
size of such an outbreak is also given. Finally, the model is fitted to three
empirical weighted networks of importance for the spread of contagious diseases
and it is shown that can be substantially over- or underestimated if the
correlation between degree and weight is not taken into account
The Occurrence of Fish Remains in Modern Lake Systems : A Test of the Stratified-Lake Mode
Theories regarding the taphonomy of fishes in lacustrine environments have traditionally relied on an anoxic water column to explain the excellent preservation. This concept has never been directly tested in modern lacustrine environments that are thought to be analogous to the lacustrine environments predicted by the Stratified-lake Model. This research tested that model by searching for fish remains in 38 collected bottom samples of six modern lacustrine analogues, including Fayetteville Green Lake, New York. The bottom sediments of a warm, holomictic, shallow, and saline lake (Salton Sea, California) were also examined. Although laminated sediments were found in all of the lakes studied, only the Salton Sea sediments contained fish remains. This was surprising in that one would have expected the opposite: abundant fish remains in the stratified lakes and few, if any in the non-stratified, saline lake.
In addition to the above described study, a preliminary study of the taphonomic processes effecting fish carcasses was carried out at Lake Perris, CA. Fresh fish carcasses were lowered in buckets to the bottom of the lake in both the epilimnion (water temperature \u3e15 deg. c. and oxygenated) as well as the hypolimnion (water temperatureanoxic), directly testing the effects of oxygen content, temperature, and pressure on the preservation of fishes. In the warm, oxygenated water decomposition took place, producing enough gasses in the fish bodies to cause them to float to the surface. In the cool, anoxic environment, decomposition of the fleshy parts was initiated, but not enough gasses were produced to cause the fish to float to the surface. Further study is needed to better understand the separate effects of oxygen content, temperature, and pressure on the taphonomy of fishes.
The results of this research strongly suggest that anoxia alone is not adequate to preserve fish remains and that some other physical, chemical, and/or biological condition may be necessary for the preservation of fishes. The results obtained at Salton Sea suggests that saline, alkaline lake waters may be important in the taphonomic process. Further studies in these environments should be productive
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