Dust from Australia- A reappraisal

This paper reviews the meteorological events of October 1928 associated with severe duststorms in Australia and subsequent transport of dust to New Zealand. In the light of contemporary knowledge of the jet streams, and from reappraisal of the original synoptic charts, reported meteorological conditions and press reports pertaining to these duststorms, it is postulated that for dust to be deposited upon New Zealand within 24 hours, of duststorms in Australia it presumably travelled via the jet stream region of the' middle and upper troposphere

Development of the Innate Immune Response in NestlingTree Swallows (Tachycineta bicolor)

The innate immune system provides an immediate, short term, first line of defense from pathogens; its appearance early in development in vertebrates is evidence of its critical importance. Even so, few studies have investigated the development of the immune response as juveniles transition into adults. Ultimately, the ability to respond to pathogens confers fitness benefits in terms of health, survival, and reproductive success, and it follows that functions such as rapid growth cannot be fully met simultaneously since energy is a limiting resource. As a result, defense mechanisms are compromised at an early age due to energy allocation to rapid growth; therefore, immunity should increase as individuals mature. I studied the development of innate immunity in nestling Tree Swallows using microbicidal assays which were conducted in vitro to assess the ability of the immune system to kill E. coli via lysis. This research may provide insight into patterns of disease susceptibility, which in turn influence evolutionary fitness and population dynamics

Bioerosion on shore platforms developed in the Waitemata Formation, Auckland

Bioerosion - the removal of lithic substrate by the erosive activities of living organisms- has not previously been discussed for New Zealand shore platforms. This paper aims at drawing attention to bioerosion as a process active in shore platform development. Detailed reference is made to bioerosion occurring on the alternating sandstones and siltstones of the Waitemata Formation found outcropping on the coastline around Auckland. In this area several facets of shore platform morphology may be attributed to the direct effects of boring and browsing marine organisms. A classification of animals causing bioerosion, based on mechanism of erosion, is presented, and the geomorphic significance of the various groups discussed

Information criteria determine the number of active sources

With the neuroelectromagnetic inverse problem, the optimal choice of the number of sources is a difficult problem, especially in the presence of correlated noise. In this paper we present a number of information criteria that help to solve this problem. They are based on the probability density function of the measurements or their eigenvalues. Make use of the Akaike or MDL (minimum description length) correction term and all employ some sort of noise information. By extensive simulations we investigated the conditions under which these criteria yield reliable estimations. We were able to quantify two major factors of influence: (1) the precision of the noise information and (2) the signal-to-noise ratio (SNR). Here defined as the ratio of the smallest signal eigenvalues and the average of the noise eigenvalues. Furthermore, we found that the Akaike correction term tends to overestimate, due to its greater sensibility to the precision of the noise informatio

Molecular ratchets - verification of the principle of detailed balance

We argue that the recent experiments of Kelly et. al.(Angew. Chem. Int. Ed. Engl. 36, 1866 (1997)) on molecular ratchets, in addition to being in agreement with the second law of thermodynamics, is a test of the principle of detailed balance for the ratchet. We suggest new experiments, using an asymmetric ratchet, to further test the principle. We also point out methods involving a time variation of the temperature to to give it a directional motion

Coupling the PLANKTOM5.0 marine ecosystem model to the OCCAM 1º ocean general circulation model for investigation of the sensitivity of global biogeochemical cycles to variations in ecosystem complexity and physical environment

The earliest marine ecosystem models consisted of a simple representation of the main features of marine ecosystems, including, typically, variables for phytoplankton, zooplankton, nutrient and detritus (NPZD models). These have been incorporated into ocean general circulation models to give a basic representation of ecosystem function, providing predictions of bulk quantities such as global primary production, export and biomass which can be compared with available observations. A recent trend has been to increase the number of phytoplankton and zooplankton groups modelled, as analogues of different plankton groups observed to exist in the ocean, for example diatoms and cocolithophores (the so-called plankton functional type or PFT approach). It is usually assumed that the increase in complexity of the model will result in simulated ecosystems which more faithfully reproduce observations than NPZD models, but this has not been demonstrated systematically. The robustness of the PFT models to changes in model parameters and to changes to the physical environment in which it is embedded, have not been investigated. As a first step towards these goals, we incorporate a state-of-the-art PFT model, PLANKTOM5.0 into the OCCAM ocean general circulation model. A 6 year simulation is performed, covering the years 1989-1994 with identical parameter choices to an existing run of PLANKTOM5.0 coupled to the OPA general circulation model. This document describes the development of the coupled model and the 6 year simulation. Comparison with the OPA model and sensitivity of the solution to parameter choices will be described in a forthcoming journal paper

Remote sensing of tidal networks and their relation to vegetation

The study of the morphology of tidal networks and their relation to salt marsh vegetation is currently an active area of research, and a number of theories have been developed which require validation using extensive observations. Conventional methods of measuring networks and associated vegetation can be cumbersome and subjective. Recent advances in remote sensing techniques mean that these can now often reduce measurement effort whilst at the same time increasing measurement scale. The status of remote sensing of tidal networks and their relation to vegetation is reviewed. The measurement of network planforms and their associated variables is possible to sufficient resolution using digital aerial photography and airborne scanning laser altimetry (LiDAR), with LiDAR also being able to measure channel depths. A multi-level knowledge-based technique is described to extract networks from LiDAR in a semi-automated fashion. This allows objective and detailed geomorphological information on networks to be obtained over large areas of the inter-tidal zone. It is illustrated using LIDAR data of the River Ems, Germany, the Venice lagoon, and Carnforth Marsh, Morecambe Bay, UK. Examples of geomorphological variables of networks extracted from LiDAR data are given. Associated marsh vegetation can be classified into its component species using airborne hyperspectral and satellite multispectral data. Other potential applications of remote sensing for network studies include determining spatial relationships between networks and vegetation, measuring marsh platform vegetation roughness, in-channel velocities and sediment processes, studying salt pans, and for marsh restoration schemes

Alternative hypotheses linking the immune system and mate choice for good genes

Why do males often have extravagant morphological and behavioural traits, and why do females prefer to mate with such males? The answers have been the focus of considerable debate since Darwin's 'The descent of man, and selection in relation to sex' appeared in 1871. Recently, the broadening of investigation to include fields outside evolutionary biology has shed new light on mate choice and sexual selection. Here, we focus on a specific set of hypotheses relating the biology of resisting disease-causing organisms with the production of condition-dependent sexual signals (advertisements). We present a framework that distinguishes three different hypotheses about trade-offs within the immune system that affect general condition. The original Hamilton & Zuk hypothesis suggests that hosts fight off disease via resistance to particular pathogens, which lowers resistance to other pathogens. Changes in pathogens over evolutionary time in turn favours changes in which genes confer the best resistance. Alternatively, the immunocompetence hypotheses suggest that the energetic costs of mounting a response to any pathogen compete for resources with other things, such as producing or maintaining advertisements. Finally, improving resistance to pathogens could increase the negative impacts of the immune system on the host, via immunopathologies such as allergies or autoimmune diseases. If both disease and immunopathology affect condition, then sexual advertisements could signal a balance between the two. Studies of hypothesized links between genes, condition, the immune system and advertisements will require careful consideration of which hypothesis is being considered, and may necessitate different measures of immune system responses and different experimental protocols

Prediction of fatigue life in composite materials using thermoelastic stress analysis

Thermoelastic Stress Analysis (TSA) is developed to provide a prediction of fatigue life in glass reinforced polymers. A test specimens has been designed to promote cracking and a methodology is defined that allows the measurement of the strain in the damaged region. It is shown that a TSA approach can evaluate fibre breakage, matrix cracking and delamination damage. A strain based metric is established based on calibrated data obtained from the TSA, which can be used to assess the condition of a component throughout its fatigue life