Population dynamics and gene flow of Helicoverpa armigera (Lepidoptera : Noctuidae) on cotton and grain crops in the Murrumbidgee Valley, Australia

The population dynamics of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) in the Murrumbidgee Valley, Australia, has been characterized using five highly variable microsatellite loci. In the 2001-2002 growing season, there were very high levels of migration into the Murrumbidgee Valley with no detectable genetic structuring, consistent with previous analyses on a national scale. By contrast, there was significant genetic structuring over the 2002-2003 growing season, with three distinct genetic types detected. The first type corresponded to the first two generations and was derived from local individuals emerging from diapause and their progeny. The second genetic type corresponded to generation 3 and resulted from substantial immigration into the region. There was another genetic shift in generation 4, which accounts for the third genetic type of the season. This genetic shift occurred despite low levels of immigration. During the third generation of the 2002-2003 growing season, different population dynamics was characterized for H. armigera on maize, Zea mays L., and cotton Gossipium hirsutum L. Populations on cotton tended to cycle independently with very little immigration from outside the region or from maize within the region. Maize acted as a major sink for immigrants from cotton and from outside the region. If resistance were to develop on cotton under these circumstances, susceptible individuals from maize or from other regions would not dilute this resistance. In addition, resistance is likely to be transferred to maize and be perpetuated until diapause, from where it may reemerge next season. If low levels of immigration were to occur on transgenic cotton, this may undermine the effectiveness of refugia, especially noncotton refugia.

Burning questions, but no burning answers: collocation and idiomaticity

The attention of linguists has increasingly shifted from grammar to lexis. Collocation has emerged as a key feature of lexis. Research using large language corpora has not only helped to identify the significant collocates of individual words but also to confirm the importance of collocation in the language system. John Sinclair has suggested that language operates on two principles: open choice and idiom. If so, then collocation would appear to be the minimal level of idiomaticity. One problem with collocation is that words that habitually co-occur form less distinct, often discontinuous, idiomatic units, whereas grammar generally works with more precisely delineated and contiguous structural units. This paper uses examples from corpus evidence to look at various aspects of collocation.

Differences in β-amyloid ( β A4) deposition in human patients with Down's syndrome and sporadic Alzheimer's disease

The density of diffuse, primitive, classic and compact β-amyloid ( β A4) deposits was estimated in the hippocampus and adjacent gyri in human patients with Down's syndrome (DS) and sporadic Alzheimer's disease (AD). The objective of the study was to determine whether there were differences in β A4 deposition in DS and sporadic AD and whether these differences could be attributed to overexpression of the amyloid precursor gene (APP) in DS. Total β A4 deposit density was greater in DS than AD in all brain regions studied but the DS/AD density ratios varied between brain regions. In the majority of brain regions, the ratio of primitive to diffuse β A4 deposits was greater in DS but the ratio of classic to diffuse deposits was greater in AD. The data were consistent with the hypothesis that overexpression of the APP gene in DS may lead to increased β A4 deposition. However, local brain factors also appear to be important in β A4 deposition in DS. Overexpression of the APP gene may also be responsible for increased production of paired helical filaments (PHF) and result in enhanced formation of primitive β A4 deposits in DS. In addition, increased formation of classic deposits in AD suggests that factors necessary for the production of a compact amyloid core are enhanced in AD compared with DS. © 1994.

Characteristics of visual function in Asperger’s syndrome and the autism spectrum

Autism is a pervasive developmental disorder and Asperger’s syndrome is part of the spectrum of autism disorders. This thesis aims to: • Review and investigate current theories concerning visual function in individuals with Asperger’s syndrome and high functioning autism spectrum disorder and to translate the findings into clinical practice by developing a specific protocol for the eye examination of individuals of this population. • Investigate whether those with Asperger’s syndrome are more likely to suffer from Meares-Irlen syndrome and/or dyslexia. • Assess the integrity of the M-cell pathway in Asperger’s syndrome using perimetric tests available in optometric practice to investigate and also to describe the nature of any defects. • Evaluate eye movement strategies in Asperger’s whilst viewing both text and images. Also to evaluate the most appropriate methodology for investigating eye movements; namely optical digital eye tracking and electrophysiology methodologies. Findings of the investigations include • Eye examinations for individuals with Asperger’s syndrome should contain the same testing methods as for the general population, with special consideration for clear communication. • There is a depression of M-pathway visual field sensitivity in 57% (8/14) of people with Asperger’s syndrome, supporting previous evidence for an M-cell deficit in some individuals. • There is a raised prevalence of dyslexia in Asperger’s syndrome (26% of a sample of 31) but not necessarily of Meares-Irlen syndrome. • Gaze strategies are abnormal in Asperger’s syndrome, for both reading and viewing of images. With increased saccadic movement and decreased viewing of faces in comparison to background detail.

Spray drier simulation and air flow pattern studies

The literature pertaining to the key stages of spray drying has been reviewed in the context of the mathematical modelling of drier performance. A critical review is also presented of previous spray drying models. A new mathematical model has been developed for prediction of spray drier performance. This is applicable to slurries of rigid, porous crust-forming materials to predict trajectories and drying profiles for droplets with a distribution of sizes sprayed from a centrifugal pressure nozzle. The model has been validated by comparing model predictions to experimental data from a pilot-scale counter-current drier and from a full-scale co-current drier. For the latter, the computed product moisture content was within 2%, and the computed air exit temperature within 10oC of experimental data. Air flow patterns have been investigated in a 1.2m diameter transparent countercurrent spray tower by flow visualisation. Smoke was introduced into various zones within the tower to trace the direction, and gauge the intensity, of the air flow. By means of a set of variable-angle air inlet nozzles, a variety of air entry configurations was investigated. The existence of a core of high rotational and axial velocity channelling up the axis of the tower was confirmed. The stability of flow within the core was found to be strongly dependent upon the air entry arrangement. A probe was developed for the measurement of air temperature and humidity profiles. This was employed for studying evaporation of pure water drops in a 1.2m diameter pilot-scale counter-current drier. A rapid approach to the exit air properties was detected within a 1m distance from the air entry ports. Measured radial profiles were found to be virtually flat but, from the axial profiles, the existence of plug-flow, well-mixed-flow and some degree of air short-circuiting can be inferred. The model and conclusions should assist in the improved design and optimum operation of industrial spray driers.