Dynamic Properties of Giant Muscle Fibers of the Barnacle

Giant muscle fibers of the barnacle give graded, relativelyslow contractions, A plateau level, termed the unit response,occurs with stimuli of 3 msec, but pulses longer than 10–15msec give much greater tension or shortening. Repetitive stimulationwith pulses of 3 msec leads to a tetanus. The magnitude of activestate was determined, and found to be also graded in natureand slow to develop, though early in onset. The full developmentof active state requires 80–120 msec. A high level ofeffective series-elasticity was associated with the sarcomeresthemselves.     

Gregarious flowering in a lowland tropical rainforest: A possible response to disturbance by Cyclone Winifred

Observations in tropical lowland rainforests damaged by Cyclone Winifred on 1 February 1986 suggest that the disturbance has been followed by an unusual burst of flowering. Fifty-four species of concurrently flowering shrubs and trees were recorded in early March along a 4 km road transect in a cyclone-damaged forest. Approximately 80% of the smaller tree and shrub species observed were flowering. Twelve species which had flowered and fruited prior to the cyclone flowered again. Some species which normally flower following periods of partial or complete deciduousness in the drier months of the year flowered after being defoliated by the cyclone. Widespread defoliation of the rainforests, together with the hot, dry weather which followed the cyclone, exposed the understorey layers to abrupt increases in temperature, insolation, and water stress. It is postulated that these environmental changes may have effected the synchronization of flowering of a larger number of species than would normally occur. It is suggested that longterm changes in the species composition of the damaged forests as a result of coincidences of seed availability and regenerative space may occur.     

Vision and the foraging technique of skimmers (Rynchopidae)

In birds, the position and extent of the region of binocular vision appears to be determined primarily by feeding ecology. Of prime importance is the degree to which vision is used for the precise control of bill position when foraging. Skimmers (Rynchops, Rynchopidae, Charadriiformes) exhibit a unique foraging behaviour and associated structural adaptations. When foraging they fly low and straight over water with the mouth open and the mandible partially submerged. Items that are hit by the lower mandible are grasped by a rapid reflex bill closure. It is believed that this unique ‘skimming’ foraging technique is guided by tactile rather than visual cues. It is predicted therefore that the visual fields of skimmers will have similar topography to those of other tactile feeding birds. We determined retinal visual fields in Black Skimmers Rynchops niger using an ophthalmoscopic reflex technique. Contrary to expectation the visual fields of Black Skimmers are not like those of other tactile feeders. They show high similarity with those of birds that feed by precision‐pecking. The projection of the bill tip when the mouth is closed and when open (as in skimming) falls within the frontal binocular field and there is an extensive blind area above and behind the head. We argue that this visual field topography functions to achieve accurate bill positioning with respect to the water surface when skimming and, because foraging skimmers cannot determine the identity of what they are seizing as they skim, to permit the visual identification of prey items held between the mandibles after they have been taken from the water surface. When skimming, only a small portion of the binocular field, approximately 5° wide and extending 5° above the horizontal, looks in the direction of travel. The small size of this forward‐facing region of binocularity in skimmers suggests that control of locomotion in birds does not necessarily require extensive binocularity in the direction of travel.     

Arthropod body-plan evolution in the Cambrian with an example from anomalocaridid muscle

The ancestor of the arthropods is widely thought to have possessed a hydrostatic skeleton surrounded by peripheral longitudinal and circular musculature, as exhibited by the extant onychophorans. However, the transition to a lever-style musculature system with an articulating exoskeleton poses a difficult problem in functional evolution: did the musculature or the exoskeleton evolve first, and how? Here, by reference to the musculature of the Lower Cambrian stem-group arthropod Pambdelurion, the problem is resolved in terms of preadaptation and functional degeneracy without recourse to saltational notions. Cambrian taxa lying in the stem-groups of the modern phyla may thus be shown to provide unique evidence for the functional progression involved in the assembly of the extant body plans and obviate the need for exotic genetic or developmental mechanisms to explain the evolution of integrated and complex body plans. The notion of the phylum representing a particularly significant level of organization is thereby brought into question.     

Steps,challenges and lessons in developing community mental health care

This paper summarises our own accumulated experience from developing community-orientated mental health services in England and Italy over the last 20-30 years. From this we have provisionally concluded that the following issues are central to the development of balanced mental health services: a) services need to reflect the priorities of service users and carers; b) evidence supports the need for both hospital and community services; c) services need to be provided close to home; d) some services need to be mobile rather than static; e) interventions need to address both symptoms and disabilities; and f) treatment has to be specific to individual needs. In this paper we consider ten key challenges that often face those trying to develop community-based mental health services: a) dealing with anxiety and uncertainty; b) compensating for a possible lack of structure in community services; c) learning how to initiate new developments; d) managing opposition to change within the mental health system; e) responding to opposition from neighbours; f) negotiating financial obstacles; g) avoiding system rigidities; h) bridging boundaries and barriers; i) maintaining staff morale; and j) creating locally relevant ser- vices rather than seeking “the right answer” from elsewhere.     

Testing Predictions of the Prey of Lion Derived From Modeled Prey Preferences

Abstract: Apex predators are often threatened with extinction, and reintroduction is one method conservation managers are using to secure their persistence. Yet the ability to predict what these predators will eat upon reintroduction is lacking. Here we test predictions of the diet of the lion (Panthera leo), derived from dietary electivity index and optimality theory, using independent data collected from reintroduced and resident populations. We solved the Jacobs’ index preference equation for each prey species of the lion using values calculated by Hayward and Kerley (2005) and prey abundance data from 4 reintroduction sites and one resident lion population over several years. We then compared these estimates with actual kill data gathered from each site and time period, using the log-likelihood ratio and linear regression. The model precisely predicted the observed number of kills in 9 of the 13 tests. There was a highly significant linear relationship between the number of lion kills predicted to occur at a site and the number observed for all but one site (x̄r² = 0.612; β = 1.03). Predicting predator diet will allow conservation managers to stop responding and start planning in advance for reintroductions and environmental variation. Furthermore, ensuring that sufficient food resources are available is likely to increase the success of reintroduction projects. In addition, managers responsible for threatened prey species will be able to predict the vulnerability of these species to predation in the event of predator reintroductions or changes in abundance. These methods are applicable to virtually all large predators that have been sufficiently studied.     

Genetic variation and diadromy in some native New Zealand galaxiids (Teleostei: Galaxiidae)

We examined genetic variation at 13 isozyme loci in three diadromous and two non-diadromous species of galaxiid fish from streams in South and Stewart Islands of New Zealand. Analysis of allele frequency data revealed higher F_s7 and Nei's D values among conspecific populations of the non-diadromous species. We propose that the genetic structurings of these species are affected by their migratory behaviours. We suggest that the derived condition of non-diadromous behaviour may increase scope for speciation, but also the probability of extinction. This is exacerbated by population fragmentation over the last century.     

Physiological Aspects of Time of Application of Copper to Wheat Plants

Time of application of Cu as soil dressing or foliar spray hadlarge effects on grain yield of wheat plants grown in Cu-deficientsoil in the glasshouse. Times of application of Cu (4 mg perpot in one dose) ranged from sowing to maturity in weekly intervals.The soil dressing of Cu produced excellent grain yield if appliedany time from sowing to early boot stage. Little or no grainformed on any tillers which had passed this critical early bootstage at the time of application; the pollen produced by thesetillers was non-viable, anthers were not exserted, and maturationwas delayed. These results suggest that microsporogenesis wasinterrupted by Cu deficiency at or near meiosis. Tillering wasthe optimum time for foliar application of Cu (CuSO₄ + Ca(0H)₂in suspension); early or late applications failed to producegrain. However, this form of Cu proved unsatisfactory for foliarapplication under glasshouse conditions, possibly owing to theabsence of rain or dew.