Description:
The paper continues investigations of stationarity and regularity properties of collections of sets in normed spaces. It contains a summary of different characterizations (both primal and dual) of regularity and a list of sufficient conditions for a collection of sets to be regular.
Description:
Competition in a natural system may be interspecific or intraspecific. In semiarid ecosystems, competition for resources between established neighboring grass species and newly recruited seedlings is very high. To examine the effects of grass species density, growing space and time of establishment on Eucalyptus victrix seedlings (interspecific competition), and the effect of density and growing space within E. victrix (intraspecific competition) we conducted an experiment under controlled conditions. We tested four hypotheses (i) E. victrix seedling growth is not affected by grass density; (ii) there is no difference in E. victrix survival and growth between early and later grass establishment; (iii) interspecific competition is not more intense than intraspecific competition in E. victrix ; and (iv) growth of E. victrix seedlings is not dependent on available growing space. In a monoculture of E. victrix , seedling mortality was higher (10%) in large pots. In mixed culture pots, where E. victrix seedlings and grass seedlings were planted on the same day, E. victrix seedlings survived for up to 4 weeks, but started to die after week five in the smallest pots. However, mortalities occurred in pots of all sizes when grass was established before E. victrix seedlings. Results also indicated that the resources necessary for the growth of individual E. victrix seedlings were more limiting under conditions of increased density of neighboring grass species rather than intraspecific competition. In particular, photosynthetic area of E. victrix seedlings was drastically reduced in mixed cultures. Although density, pot size and time of planting had impacts on E. victrix seedlings, the patterns of these impacts were variable.
Description:
The psychological models of panic disorder predict that people with this anxiety disorder are able to accurately estimate changes in somatic sensations. This study investigated whether nonclinical panickers, at risk for developing panic disorder, demonstrate enhanced interoceptive ability for changes in sympathetic arousal. Twenty people with nonclinical panic and 36 nonpanic controls estimated changes in overall sympathetic arousal, as measured by pulse transit time. A greater proportion of the nonclinical panickers than nonpanic controls met criterion for accurate interoceptive ability. As a group, nonclinical panickers also demonstrated more accurate perception of sympathetic arousal but only when it changed in predictable ways. Anxiety sensitivity and trait anxiety also appeared related to enhanced interoception, particularly in people who had experienced nonclinical panic. People who are at risk for the development of panic disorder may therefore demonstrate enhanced interoceptive ability for sympathetic arousal.
Description:
We consider problems of vector optimization with preferences that are not necessarily a pre-order relation. We introduce the class of functions which can serve for a scalarization of these problems and consider a scalar duality based on recently developed methods for non-linear penalization scalar problems with a single constraint.
Description:
There is little published information on the impacts of exotic fishes in the shallow slightly saline, closed catchment lakes of western Victoria. The present study assessed the diet of exotic carp (Cyprinus carpio) from two lakes of western Victoria (Lake Colac and Lake Modewarre) between November 1999-September 2001, using a numerical and volumetric method of gut contents analysis. Carp larvae <2 cm total length fed exclusively on microcrustacea (Cladocera and Copepoda). At a mean total length of >2 cm carp larvae shifted their diet to include benthic food resources, but microcrustacea still dominated the larval diet. Small carp (≤15 cm) showed a high preference for microcrustacea and tended to avoid benthic macroinvertebrate food resources. As carp size increased the proportion of macroinvertebrates in gut contents increased. Medium (15-40 cm) and large sized carp (>40 cm) displayed broad food assemblages in their guts with microcrustacea, Gastropoda, Ostracoda, Amphipoda and detritus being dominant. Carp showed a selective preference for Diptera and a balanced preference for Amphipoda. Schoener's dietary overlap was high between small and medium carp (0.55-0.65) and medium and large carp (0.72-0.74) but was low between small and large carp (0.36-0.44). When considering only benthic macroinvertebrate food resources, Hurlbert's dietary overlap between size classes of carp remained reasonably low. There were no observable seasonal patterns in the diet of carp in the two lakes but the proportion of the food items in the gut varied between sampling occasions. This study identified the potential of exotic carp in altering lake function by feeding predominantly on microcrustacea, thus causing a 'top-down' trophic cascade.
Description:
Diatoms are among the most widely used indicators of human and climate induced wetland salinity history in the world. This is particularly as a result of the development of diatom-based models for inferring past salinity. These models have primarily been developed from relationships between diatoms and salinity measured at the time of sampling or during the preceding year. Although within site variation in salinity has the potential to reduce the efficacy of such models, its influence has been rarely considered. Hence, diatom-conductivity relationships in eight seasonally monitored wetlands have been investigated. In developing a diatom-conductivity transfer function from these sites, we sought to assess the influence of conductivity variation on diatom inference model performance. Our sites were characterised by variability in conductivity that was not correlated to its range and thus were well suited to an investigation of this type. We found, contrary to expectations, that short-term (seasonal) changes in conductivity which were often dramatic did not result in unduly reduced transfer function performance. By contrast, sites that were more variable in the medium term (5-6 years) tended to have larger model errors. In addition, we identified a secondary ecological gradient in the diatom data which could not be related to any measured variable (including pH, turbidity or nutrient concentrations).
Description:
A sequential extraction procedure was used to investigate the influence of long-term phosphate fertilization on the distribution of cadmium throughout the major components of krasnozemic soils in the potato growing district located to the East of Ballarat, Victoria, Australia. The soil fractions investigated consisted of the water soluble, exchangeable, weakly bound to metal oxides, strongly bound to metal oxides, bound to organic material and residual. Other soil parameters, such as pHH2O, pHCaCl2, electrolytical conductivity and total organic material were investigated. The concentrations of Ca, Mg, Fe, Mn and Zn in each soil fraction were also measured. The total concentration of cadmium in the farmed soils had increased from the background level of 100.5