200,805 research outputs found
Adapting strata and community title buildings for climate change
No full textAbstract This report outlines the findings of a study that has sought to inform policy making concerned with preparing strata titled communities to deal with challenges that are expected to result from climate change. The report develops and analyses 24 recommendations designed to advance the capacity of strata titled communities to cope with climate change.The report provides a description of five research phases that have informed the study. Initially a literature review was undertaken. This review focused on climate change impacts on buildings and also issues surrounding the management of strata titled complexes. Next a review of the most pertinent Australian legislation relating to insurance, property maintenance and the funding of common property capital expenditures in strata titled schemes was undertaken. The study’s first empirical phase involved a meeting with an eleven person industry reference group. This group met on two subsequent occasions and represented a valuable sounding board that informed the study’s evolution. Next, eighteen interviews were conducted with individuals representing a range of strata title stakeholder groups. The study’s final empirical phase involved the conduct of an on-line questionnaire survey. This survey was designed to investigate the current climate change preparedness of strata title communities and also to gauge the relative merit of sixteen recommendations developed during the interview phase. The survey was also used as an opportunity to generate further recommendations. Following an analysis and distillation of feedback provided by 450 questionnaire respondents, eight further recommendations were developed.Analysis of data collected during the study’s interview phase resulted in the distillation of six thematic issues that should be considered when seeking to better prepare strata titled communities for a world of climate change. These six themes are: 1) Facilitating unit owner awareness of climate change implications; 2) Facilitating information availability to key decision makers; 3) Facilitating strata and community title complex decision making; 4) Funding building adaptation work; 5) Weather event emergency management; and 6) Insurance as risk management.The 24 recommendations advanced in the report cover a wide range of facets relating to strata title building, living and management. The range of issues addressed in the recommendations include factors relating to building construction and resilience rating, improved climate change education of strata title stakeholders, insurance, emergency management, building decision making issues, and bank lending. The breadth of the recommendations is also evident from the fact that they are directed to a broad range of strata title stakeholders that include unit owners, strata managers, resident managers, state and federal governments, insurance companies, sinking fund forecasters and banks.By: Chris Guilding, Jan Warnken, Francesco Andreone and Dawne Lamminmak
The problem of a true consensual light reflex in birds
No full textThe problem of the consensual light reflex in birds has been studied with the aid of 2 techniques which have recently been introduced into ocular physiology: examination under infrared light and photocoagulation of the optic papilla. It was, therefore, concluded that in the owl a true consensual light reflex exists. There is also the possibility of a "pseudo-consensual" light reflex due to the light which crosses the interocular bony septum; but the contribution of this "pseudo-consensual-reflex," when present, is quantitatively negligible when compared with the true consensual reflex. ((c) 1997 APA/PsycINFO, all rights reserved
Structural plasticity of climbing fibers and the growth-associated protein GAP-43
No full textStructural plasticity occurs physiologically or after brain damage to adapt or re-establish proper synaptic connections. This capacity depends on several intrinsic and extrinsic determinants that differ between neuron types. We reviewed the significant endogenous regenerative potential of the neurons of the inferior olive in the adult rodent brain and the structural remodeling of the terminal arbor of their axons the climbing fiber under various experimental conditions, focusing on the growth-associated protein GAP-43. Climbing fibers undergo remarkable collateral sprouting in the presence of denervated Purkinje cells that are available for new innervation. In addition, severed olivo-cerebellar axons regenerate across the white matter through a graft of embryonic Schwann cells. In contrast, climbing fibers undergo a regressive modification when their target is deleted. In vivo knockdown of GAP-43 in olivary neurons, leads to the atrophy of their climbing fibers and a reduction in the ability to sprout toward surrounding denervated Purkinje cells. These findings demonstrate that GAP-43 is essential for promoting denervation-induced sprouting and maintaining normal climbing fiber architecture
Embryonic purkinje cells grafted on the surface of the adult uninjured rat cerebellum migrate in the host parenchyma and induce sprouting of intact climbing fibres
No full textBy grafting solid pieces of cerebellar anlage onto the surface of the adult rat cerebellum, we have investigated the problem of the interactions between embryonic and adult neurons in an intact brain. A few days after grafting, embryonic astrocytic processes crossed the graft--host interface and radiated into the recipient molecular layer. Several grafted Purkinje cells also migrated into the host brain along such processes as well as adult Bergmann glia. Adult climbing fibres, labelled by means of Phaseolus vulgaris leucoagglutinin (PHA-L), sprouted new collateral branches which terminated on embryonic Purkinje cells at both extra- and intraparenchymal levels. No sign of activation of host astroglia or microglia was evident in the host cerebellum in relation to these processes. Embryonic Purkinje cells which migrated into the host cerebellum developed an adult-like morphology. Intraparenchymal grafts of neocortical embryonic tissue induced conspicuous growth of host olivary axons, characterized by a pattern which was different from that observed following cerebellar grafts. By contrast, when neocortical tissue was placed onto the surface of the recipient cerebellum, graft--host interactions were limited and climbing fibre sprouting was rarely seen. These results show that (i) supernumerary Purkinje cells can penetrate and settle in the adult intact cerebellar cortex, (ii) adult climbing fibres are able to innervate these new targets in the absence of any injury or activation of non-neuronal cells of the adult brain, and (iii) in the absence of damage to the adult brain, the plasticity of adult olivary axons is specifically elicited and controlled by embryonic Purkinje cells
Exposure to kainic acid mimics the effects of axotomy in cerebellar Purkinje cells of the adult rat
No full textWe have investigated the long-term structural changes which affect Purkinje cells exposed to a single dose of kainic acid. Following intraparenchymal injection of the excitotoxin in the cerebellar cortex (1 microliter of a 1 mg/ml solution), Purkinje cells which survived within the lesioned area or close to its edges showed remarkable axonal abnormalities, involving the formation of torpedoes, hypertrophy of recurrent collaterals and atrophy of the corticofugal portion of the axon. In addition, their dendritic trees were often affected by conspicuous regressive alterations. The climbing fibres contacting these Purkinje cells were characterized by thick perisomatic plexuses, whereas their peridendritic branches were atrophic. The dendrites innervated by such atrophic olivary arbours were studded with huge numbers of newly formed spines. These alterations were already present a few days after kainic acid administration and persisted for the total period of observation of 6 months after the lesion. The remarkable similarity between the abnormalities of Purkinje cells exposed to kainic acid and those observed after axotomy indicates that in these two conditions common mechanisms determine analogous long-lasting modifications in the affected neurons. It is proposed that kainic acid-induced intracellular calcium overload disrupts cytoskeletal components and impairs axonal transport, thus depriving the affected Purkinje cells of retrograde trophic influences from their target neurons. As a consequence the affected neurons undergo long-lasting regressive modifications and compensatory remodelling phenomena
Seabed foraging by Antarctic krill: Implications for stock assessment, bentho-pelagic coupling, and the vertical transfer of iron
No full textA compilation of more than 30 studies shows that adult Antarctic krill (Euphausia superba) may frequent benthic habitats year-round, in shelf as well as oceanic waters and throughout their circumpolar range. Net and acoustic data from the Scotia Sea show that in summer 2-20% of the population reside at depths between 200 and 2000 m, and that large aggregations can form above the seabed. Local differences in the vertical distribution of krill indicate that reduced feeding success in surface waters, either due to predator encounter or food shortage, might initiate such deep migrations and results in benthic feeding. Fatty acid and microscopic analyses of stomach content confirm two different foraging habitats for Antarctic krill: the upper ocean, where fresh phytoplankton is the main food source, and deeper water or the seabed, where detritus and copepods are consumed. Krill caught in upper waters retain signals of benthic feeding, suggesting frequent and dynamic exchange between surface and seabed. Krill contained up to 260 nmol iron per stomach when returning from seabed feeding. About 5% of this iron is labile, i.e., potentially available to phytoplankton. Due to their large biomass, frequent benthic feeding, and acidic digestion of particulate iron, krill might facilitate an input of new iron to Southern Ocean surface waters. Deep migrations and foraging at the seabed are significant parts of krill ecology, and the vertical fluxes involved in this behavior are important for the coupling of benthic and pelagic food webs and their elemental repositories
Embryonic Purkinje cells grafted on the surface of the cerebellar cortex integrate in the adult unlesioned cerebellum
No full textThe presence of an injury or the selective degeneration of specific neuronal populations is commonly assumed to be a necessary prerequisite for the survival and the integration of grafted neurons in the recipient brain. In the present study we have placed solid grafts of cerebellar anlage in the fourth ventricle of adult rats, in close contact with the host cerebellar cortex, to assess the capacity of embryonic Purkinje cells to interact with adult neurons and integrate in the unlesioned cerebellar cortex. Numerous grafted Purkinje cells are indeed able to leave the implant and migrate into the host molecular layer, where they develop adult structural features. In addition, such cells are able to elicit the growth of host climbing fibre sprouts which end in newly formed arborizations impinging upon their dendritic trees. Climbing fibre collateral branches also penetrate the implant to innervate Purkinje cells which have not migrated in the host cerebellum. These results show that embryonic Purkinje cells are able to survive and integrate in an adult unlesioned cerebellar cortex. In addition, adult olivary axons respond to the increased size of the target population by expanding their terminal domain to innervate grafted Purkinje cells
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