Modelling cell separation during plant organ abscission

A simple mathematical model is presented to describe the cell separation process that plants undertake in order to deliberately shed organs. The focus here is on modelling the production of the enzyme polygalacturonase, which breaks down pectin that provides natural cell-to-cell adhesion in the localised abscission zone. A coupled system of three ordinary differential equations is given for a single cell, and then extended to hold for a layer of cells in the abscission zone. Simple observations are made based on the results of this preliminary model and, furthermore, a number of opportunities for applied mathematicians to make contributions in this subject area are discussed.

Home-based activity program for older people with depressive symptoms: DeLLITE–A randomized controlled trial

PURPOSE We wanted to assess the effectiveness of a home-based physical activity program, the Depression in Late Life Intervention Trial of Exercise (DeLLITE), in improving function, quality of life, and mood in older people with depressive symptoms. METHODS We undertook a randomized controlled trial involving 193 people aged 75 years and older with depressive symptoms at enrollment who were recruited from primary health care practices in Auckland, New Zealand. Participants received either an individualized physical activity program or social visits to control for the contact time of the activity intervention delivered over 6 months. Primary outcome measures were function, a short physical performance battery comprising balance and mobility, and the Nottingham Extended Activities of Daily Living scale. Secondary outcome measures were quality of life, the Medical Outcomes Study 36-item short form, mood, Geriatric Depression Scale (GDS-15), physical activity, Auckland Heart Study Physical Activity Questionnaire, and self-report of falls. Repeated measures analyses tested the differential impact on outcomes over 12 months’ follow-up. RESULTS The mean age of the participants was 81 years, and 59% were women. All participants scored in the at–risk category on the depression screen, 53% had a Diagnostic and Statistical Manual of Mental Disorders or International Classification of Diseases, Tenth Revision diagnosis of major depression or scored more than 4 on the GDS-15 at baseline, indicating moderate or severe depression. Almost all participants, 187 (97%), completed the trial. Overall there were no differences in the impact of the 2 interventions on outcomes. Mood and mental health related quality of life improved for both groups. CONCLUSION he DeLLITE activity program improved mood and quality of life for older people with depressive symptoms as much as the effect of social visits. Future social and activity interventions should be tested against a true usual care control.

Zombies on the road: A holistic design approach to balancing gamification and safe driving

This paper explores novel driving experiences that make use of gamification and augmented reality in the car. We discuss our design considerations, which are grounded in road safety psychology and video game design theory. We aim to address the tension between safe driving practices and player engagement. Specifically, we propose a holistic, iterative thinking process inspired by game design cognition and share our insights generated through the application of this process. We present preliminary game concepts that blend digital components with physical elements from the driving environment. We further highlight how this design process helped us to iteratively evolve these concepts towards being safer while maintaining fun. These insights and game design cognition itself will be useful to the AutomotiveUI community investigating similar novel driving experiences.

Insolvency academics contributing to the review of insolvency laws: An Australian perspective

Introduction 1 It gives me great pleasure to contribute to this publication to honour Professor Ian Fletcher on his retirement as Foundation Chair of the INSOL International Academic Group. A collection of essays that include topics on domestic, cross-border and international insolvency appropriately reflects the breadth of Professor Fletcher’s impact on the scholarship of insolvency law – not only in his “home” jurisdiction of England and Wales and closer to home in Europe, but also stretching around the globe, in this case, to Australia. 2 In the early 1990s when I first began to research in the area of cross-border insolvency law, a colleague mentioned that they had recently attended the XIIIth International Congress of Comparative Law in Montreal in August 1990 and heard the Cross-border Insolvency: General Report expertly delivered by an English academic, Ian Fletcher, who was widely regarded as an authority in the area. This was my first introduction to Professor Fletcher’s work and over the intervening years I have referred often to his scholarship....

Zombies on the road: A holistic design approach to balancing gamification and safe driving [poster]

This paper explores novel driving experiences that make use of gamification and augmented reality in the car. We discuss our design considerations, which are grounded in road safety psychology and video game design theory. We aim to address the tension between safe driving practices and player engagement. Specifically, we propose a holistic, iterative thinking process inspired by game design cognition and share our insights generated through the application of this process. We present preliminary game concepts that blend digital components with physical elements from the driving environment. We further highlight how this design process helped us to iteratively evolve these concepts towards being safer while maintaining fun. These insights and game design cognition itself will be useful to the AutomotiveUI community investigating similar novel driving experiences.

Handling of Two Tropical Australian Sharks to Improve Quality and to Identify the Cause of Tough Texture

Sharks caught in tropical Australian waters occasionally exhibit tough texture. Two species of Carcharinid shark, originally known as the sorrah shark (Carcharinus sorrah) and the black spot shark (Carcharinus tilstoni), compose the majority of the catch. Experiments were conducted to identify the cause of tough texture and to improve the overall quality of the catch. The possibility that a cold shock reaction may occur was investigated by observing the contraction of fillets under a range of temperature conditions before freezing. The effect of on-board handling practices were evaluated using frozen shark fillets, which had been stored prior to freezing in refrigerated seawater at different rigor stages, temperatures and times as trunks. Fillets were analyzed for nucleotides, lactate, thaw pH, sarcomere length and raw and cooked shear force values. The existence of thaw rigor was also investigated. There was little difference in the texture between the individual strips of a fillet exposed to different temperatures but there were significant differences between individual sharks. A cold shock reaction could not be demonstrated in these species. The main influences on texture were of biological origin. The species, sex and size were found to have significant links with texture of fillets. The quality of the fillets deteriorated quicker during the warmer season and were at their worst if the trunks were kept on deck till post-rigor or held in 15 degree C refrigerated seawater before freezing

Volatile components associated with bacterial spoilage of tropical prawns

Analysis of headspace volatiles by gas chromatography/mass spectrometry from king (Penaeus plebejus), banana (P. merguiensis), tiger (P. esculentus/semisulcatus) and greasy (Metapenaeus bennettae) prawns stored in ice or ice slurry, which is effectively an environment of low oxygen tension, indicated the presence of amines at the early stages of storage (less than 8 days) irrespective of the nature of the storage media. Esters were more prevalent in prawns stored on ice (normal oxygen conditions) at the latter stages of storage (more than 8 days) and were only produced by Pseudomonas fragi, whereas sulphides and amines occurred whether the predominant spoilage organism was Ps.fragi or Shewanella putrefaciens. The free amino acid profiles of banana and king prawns were high in arginine (12–14%) and low in cysteine (0.1–0.17%) and methionine (0.1–0.2%). Filter sterilised raw banana prawn broth inoculated with a total of 15 cultures of Ps. fragi and S. putrefaciens and incubated for two weeks at 5°C, showed the presence of 17 major compounds in the headspace volatiles analysed using gas chromatography/mass spectrometry (GC/MS). These were mainly amines, sulphides, ketones and esters. Principal Component Analysis of the results for the comparative levels of the volatiles produced by pure cultures, inoculated into sterile prawn broth, indicated three subgroupings of the organisms; I, Ps. fragi from a particular geographic location; II, S. putrefaciens from another geographic location; and III, a mixture of Ps. fragi and S. putrefaciens from different geographic locations. The sensory impression created by the cultures was strongly related to the chemical profile as determined by GC/MS. Organisms, even within the same subgrouping classified as identical by the usual tests, produced a different range of volatiles in the same uniform substrate.

Effects of Low Dose Irradiation on the K-Value and Hypoxanthine Concentration of Fish Fillets

Fillets of five fish species were irradiated at 0, 1 and 3kGy to investigate whether the K-value test of freshness can be applied to irradiated fish. Following irradiation, the fillets were stored on ice and sampled regularly for K-value analysis. Hypoxanthine (Hx) and total nucleotide content were also determined on fillets of two species. K-values of irradiated fillets were generally lower than those of unirradiated controls. Hypoxanthine levels paralleled the K-value changes. These results indicated that quality standards based on K-values or Hx levels that have been set for unirradiated species cannot be directly applied to fish that has been irradiated. Total nucleotide content did not appear to be affected by irradiation.

Nucleotide Degradation Profiles of Iced Barramundi (Lates calcarifer) and Nile Perch (Lates niloticus) Muscle

Adenine nucleotides and their related compounds were determined in muscle extracts from two species of fish that were stored in ice after thawing. The fish were the closely related species, Australian barramundi (Lates calcarifer ) and Kenyan Nile perch (Lates niloticus ) which had different process histories. For all samples, adenine nucleotides did not exceed 6% of the total nucleotide pool. Inosine monophosphate (IMP) decreased steadily with storage. Hypoxanthine (Hx) was the major product of adenosine triphosphate (ATP) degradation in both barramundi and Nile perch, showing a steady increase with days of iced storage. The Hx level did not reach a maximum during the 9d storage period. The K-value also increased regularly with time of storage and for the later stages (i.e., 7 and 9d) and was significantly different (P < 0.01) for the two species. The iced storage life of these typical samples of barramundi and Nile perch was estimated to be 3d after thawing using a K-value of < 30% to indicate excellent quality. Despite the differences in process history the nucleotide profiles were remarkably similar during storage. This precludes the use of nucleotide levels as a means of differentiating between these species.

The microbiological status of prawns from retail and wholesale outlets in the Brisbane region

Cooked prawns from retail and wholesale outlets in the Brisbane region included a large proportion with high bacterial counts (10(6)-10(8)/g) indicating a short remaining shelflife. Microbially inferior product entering the wholesale and retail trade indicated poor handling and storage practices from point of capture all along the distribution chain to the retail outlets. Current handling practices need to be upgraded and HACCP principles adopted.

Alternatives to sodium metabisulphite for blackspot prevention in prawns

In Australia, prawns are usually treated with a 1% sodium metabisulphite solution to prevent black spot. Two alternatives, Bacterol and Snow Fresh, were compared to the standard metabisulphite treatment used by industry. Bacterol gave similar protection to sodium metabisulphite, while Snow Fresh showed potential as a substitute. The concentrations most appropriate were determined from residue levels after treatment.

Maturation studies of pecan nuts grown in Queensland

Changes in chemical composition, physical and sensory characteristics were followed in two pecan cultivars Wichita and Western Schley harvested from a commercial orchard at Gatton in Queensland seven times during 1996.Testa colour of both pecan cultivars darkened and opalescence decreased as the nuts matured. Bitterness of Western Schley pecans decreased with maturity. Colour of shuck, shell and kernel of both cultivars developed as the nuts matured. Wichita pecans were larger than Western Schley at all harvest times. Both nut-in-shell and kernel moisture decreased with maturity, whereas oil and sucrose contents increased. Both pecan cultivars had reached advanced maturation by the first harvest on March 18.