Quantitative microbial risk assessment models for consumption of raw vegetables irrigated with reclaimed water

Quantitative microbial risk assessment models for estimating the annual risk of enteric virus infection associated with consuming raw vegetables that have been overhead irrigated with nondisinfected secondary treated reclaimed water were constructed. We ran models for several different scenarios of crop type, viral concentration in effluent, and time since last irrigation event. The mean annual risk of infection was always less for cucumber than for broccoli, cabbage, or lettuce. Across the various crops, effluent qualities, and viral decay rates considered, the annual risk of infection ranged from 10–3 to 10–1 when reclaimed-water irrigation ceased 1 day before harvest and from 10–9 to 10–3 when it ceased 2 weeks before harvest. Two previously published decay coefficients were used to describe the die-off of viruses in the environment. For all combinations of crop type and effluent quality, application of the more aggressive decay coefficient led to annual risks of infection that satisfied the commonly propounded benchmark of ≤10–4, i.e., one infection or less per 10,000 people per year, providing that 14 days had elapsed since irrigation with reclaimed water. Conversely, this benchmark was not attained for any combination of crop and water quality when this withholding period was 1 day. The lower decay rate conferred markedly less protection, with broccoli and cucumber being the only crops satisfying the 10–4 standard for all water qualities after a 14-day withholding period. Sensitivity analyses on the models revealed that in nearly all cases, variation in the amount of produce consumed had the most significant effect on the total uncertainty surrounding the estimate of annual infection risk. The models presented cover what would generally be considered to be worst-case scenarios: overhead irrigation and consumption of vegetables raw. Practices such as subsurface, furrow, or drip irrigation and postharvest washing/disinfection and food preparation could substantially lower risks and need to be considered in future models, particularly for developed nations where these extra risk reduction measures are more common.

Elastic bending of steel-polymer-steel (SPS) laminates to a constant curvature

The shear strain of the interlayer in the elastic regime for a Steel-Polymer-Steel (SPS) laminate material has been studied during bending to a constant curvature. An analytical model is developed and the influence of process parameters are analyzed. The tension in the cover sheets is also determined and, finally, a moment diagram is calculated. The results show that the moment in the SPS laminate is nonuniform along the bent strip even though the curvature is constant because of the tension and compression forces introduced in the cover sheets by the shear reaction force of the interlayer material.

Energy absorption and crushing behaviour of foam-filled aluminium tubes

The crushing behaviour and energy absorption of foam filled aluminium tubular structures were investigated using the quasi-static compressive tests. The crushing behaviour of the tubular structures changed due to foam filling. The energy absorption of the foam filled tubular structures was improved significantly. Foam filling caused an interaction effect between the tube and the foam during progressive crushing, leading to an increase in the mean crushing load compared to that of the foam or tube itself. This interaction effect might be affected by several parameters such as the density of the foam, the properties of both the foam material and tube material, and the thickness and outer diameter of the tube. In particular, the interaction effect essentially depended on the ratio of the mean crushing force of the foam to that of the tube.

Differential effects of arginine, glutamate and phosphoarginine on Ca2+-activation properties of muscle fibres from crayfish and rat

The effects of two amino acids, arginine which has a positively charged side-chain and glutamate which has a negatively charged side-chain on the Ca²⁺-activation properties of the contractile apparatus were examined in four structurally and functionally different types of skeletal muscle; long- and short-sarcomere fibres from the claw muscle of the yabby (a freshwater decapod crustacean), and fast- and slow-twitch fibres from limb muscles of the rat. Single skinned fibres were activated in carefully balanced solutions of different pCa (-log₁₀[Ca²⁺]) that either contained the test solute (“test”) or not (“control”). The effect of phosphoarginine, a phosphagen that bears a nett negative charge, was also compared to the effects of arginine. Results show that (i) arginine (33-36 mmol l^-1) significantly shifted the force–pCa curve by 0.08–0.13 pCa units in the direction of increased sensitivity to Ca²⁺-activated contraction in all fibre types; (ii) phosphoarginine (9–10 mmol l^-1) induced a significant shift of the force–pCa curve by 0.18–0.24 pCa units in the direction of increased sensitivity to Ca²⁺ in mammalian fast- and slow-twitch fibres, but had no significant effects on the force–pCa relation in either long- or short-sarcomere crustacean fibres; (iii) glutamate (36–40 mmol l^-1), like arginine affected the force–pCa relation of all fibre types investigated, but in the opposite direction, causing a significant decrease in the sensitivity to Ca²⁺-activated contraction by 0.08–0.19 pCa units; (iv) arginine, phosphoarginine and glutamate had little or no effect on the maximum Ca²⁺-activated force of crustacean and mammalian fibres. The results suggest that the opposing effects of glutamate and arginine are not related to simply their charge structure, but must involve complex interactions between these molecules, Ca²⁺ and the regulatory and other myofibrillar proteins.

Investigation of plasmodiophora brassicae (clubroot disease) in vegetable brassica using arabidopsis thaliana as a model system

Clubroot, caused by Plasmodiophora brassicae, is the most devastating soil-borne disease of vegetable brassicas. It occurs all over the world and is responsible for crop losses of up to 10% every year. In Australia, the disease is being managed effectively with chemicals and cultural practices, but ideally control can be improved in the long term by the introduction of resistant cultivars. The life cycle ofP. brassicae and mode of action of plant resistance has not been fully elucidated because of the technical difficulties of working with an obligate, soil-borne plant pathogen. However, Arabidopsis thaliana, which is a host ofP. brassicae, has great potential as a model system for studying the life cycle, the infection process and development of resistance. We have developed a sand-liquid-culture system for growing Arabidopsis that allows easy observation of all life stages and, most importantly, the primary plasmodial stages within the root hair. The method was first optimised for observations of the lifecycle of the pathogen in a susceptible Arabidopsis ecotype (Col-3) where all stages of the lifecycle have now been observed and characterised. Further screening of Arabidopsis ecotypes for disease resistance has utilised one of the most virulent Australian pathotypes of brassica (ECD number 16/19/31). To date, Arabidopsis ecotype Ta-0 has shown a level of tolerance to the disease even though the roots get infected. It has been reported earlier that resistance toP. brassicae in Arabidopsis is due to one or a small number of genes. To examine changes in gene expression during the early, critical stages of infection, RNA was extracted from the susceptible and resistant ecotypes at two time points, 4 days and 17 days after inoculation. Microarray analysis will be used to investigate genome wide changes in gene expression during infection but also to identify candidate genes that may confer resistance to Australian isolates of the pathogen.

Interaction of Arabidopsis Thaliana with Plasmodiophora Brassicae

Plasmodiophora brassicae is a protistan pathogen that attacks roots of brassicaceous plant species causing devastating disease. Resistance is characterised by restriction of the pathogen and susceptibility by the development of severely malformed roots (‘clubroots’) and stunting of the plant that is associated with alterations in the synthesis of cytokinin and auxin hormones. We are examining the susceptible response in Arabidopsis and whether suppression of key resistance factors by the pathogen contributes to susceptibility. The interaction is being studied using a number of approaches including microscopy of the infection process and development of the pathogen within roots and host gene expression analysis. Quantitative PCR was used to confirm the timing of infection of roots and showed that infection occurred at day four and colonisation increased thereafter to high levels by 23 days after inoculation by which time roots were showing systemic abnormalities. To investigate the basis of this compatible interaction we have conducted a time course experiment following infection of a susceptible ecotype of Arabidopsis (Col-0) to examine whole genome geneexpression changes in the host. Differential gene expression analysis of inoculated versus control roots showed that a higher number of genes had altered expression levels at day four compared to that at day seven and at day ten. At day four the expression levels of several genes known to be important for recognition and signal transduction in resistant interactions and genes involved in the biosynthesis of lignin, phenylpropanoids and ethylene were suppressed. Suppression by P. brassicae of specific plant defence responses appears to be a key component of susceptibility in this system.

Functional status after bloodstream infection : the survivors' trajectory

There is very little information about the quality of survival for patients after bacterial and fungal bloodstream infections. This study aimed to describe the functional status and level of activities of daily living for a group of survivors of these infections. A prospective exploratory design was used to track adults for 6 months after onset of infection. Survivors were assessed for reduced or full health status. Telephone interviews, using the London Handicap Scale and the Sickness Impact Profile, provided self-assessed functional status for those able to participate; 165 adults were tracked. Before infection, only 25% of adults had an active malignancy and one-tenth required a high level of assistance with activities of daily living. Six months after infection, half of survivors had reduced health and many had not returned to their normal functional activity level. There was considerable continued reduced health in survivors, demonstrating that not only do bloodstream infections result in high short-term mortality but also in considerable longer term morbidity and profound alteration in functional health status for many survivors.

The SARS (Severe Acute Respiratory Syndrome) pandemic in Hong Kong : effects on the subjective wellbeing of elderly and younger people

Objectives: This study examined the impact of the Severe Acute Respiratory Syndrome (SARS) outbreak in Hong Kong in 2003, on the subjective wellbeing (SWB) of elderly people and a younger comparative sample. The Personal Wellbeing Index (PWI), a contemporary instrument employed to measure SWB, was also examined for its psychometric performance to substantiate its use.

Method: A total of 302 older adults (age 65 + years) and 158 younger adults (age 35-46 years) were recruited from different districts. Data were collected by individual face-to-face interviews.

Result: While elderly people living in severely infected districts showed significantly lower levels of SWB, these levels and those of the younger sample were found to remain within the normative range. A major mitigating factor was an increased sense of community-connectedness. Other characteristics linked to low wellbeing levels included chronic illness, female gender, low education and unemployment. The living districts, characterized by varying extents of infection, had stronger associations with SWB than participants' age. The PWI demonstrated good psychometric performance and also more robustness with elderly people, including its sensitivity to the sense of population threat.

Conclusion: Psychological resilience was identified among both the elderly and younger age-groups in Hong Kong during the SARS pandemic. The PWI is verified as a suitable instrument for SWB measurements.

In-situ tensile properties of a ballooning staple yarn

This study investigated the tensile properties of a rotating or ballooning staple yarn. The results indicated that the effect of rotating speed on the tensile properties of a ballooning staple yarn was significant. As the yarn rotating speed increased, the tenacity of the rotating or ballooning yarn decreased, while the yarn breaking elongation increased. The effect of rotating speed on the tenacity of a ballooning staple yarn varied for different yarns. These results demonstrated that the breaking force of a ballooning yarn was much lower than the yarn breaking force obtained from normal tensile tests. These results provide new insight into the problems of yarn breakage in yarn spinning and twisting processes.

A boarding school outbreak of pertussis in adolescents : value of laboratory diagnostic methods

Culture for Bordetella pertussis (B. pertussis) is the traditional gold standard for laboratory diagnosis of pertussis but is insensitive, especially later in the course of illness and in vaccinated persons. Interpretation of serology is limited by the lack of an appropriate reference standard. An outbreak of pertussis in a crowded boarding-school dormitory allowed evaluation of laboratory correlates of infection. Questionnaires, serum samples and throat swabs were collected from members of the exposed group. Serum samples from unexposed controls of a similar age group were used for comparison. B. pertussis PCR was performed on throat swabs, and sera were tested for IgA antibodies against whole-cell (WC) B. pertussis antigen and IgG antibodies to pertussis toxin (PT). The Centers for Disease Control and Prevention definition for pertussis was used to define clinical cases. We evaluated the use of a previously published cut-off for PT IgG of 125 EIA units (EU)/ml. Completed questionnaires were obtained from 115 students, of whom 85 (74%) reported coughing symptoms, including 32 (28%) who met the clinical case definition for pertussis. B. pertussis was detected by PCR in 17 (15%) and WC IgA in 22 (19%) students; neither correlated with symptoms, but dormitory of residence strongly predicted PCR status. The mean PT IgG geometric mean concentration, in this situation of high pertussis exposure, correlated with severity of symptoms and was significantly higher in both symptomatic and asymptomatic children exposed during the outbreak (P<0·001) than in control children. A cut-off for PT IgG of 125 EU/ml was too high in an outbreak situation to be sensitive enough to identify pertussis cases. A case of pertussis in a crowded boarding-school dormitory resulted rapidly in an outbreak. Serology and PCR were useful in identifying the outbreak and commencing disease control measures. The use of serology has mostly been evaluated in community serosurveys, where it is not possible to determine if immunity reflects vaccination, asymptomatic disease or symptomatic disease. This outbreak gave us the opportunity to evaluate the value of serology and PCR in the presence of confirmed exposure to pertussis.

The role of wild birds in the transmission of avian influenza for Australia : an ecological perspective

Waterbirds, particularly Anatidae, are natural reservoirs for low-pathogenic avian influenza and have been implicated as the primary source of infection in outbreaks of highly pathogenic avian influenza. An understanding of the movements of birds and the ecology of avian influenza viruses within the wild bird population is essential in assessing the risks to human health and production industries. Marked differences in the movements of Australian birds from those of the Northern Hemisphere emphasises the danger of generalising trends of disease prevalence to Australian conditions. Populations of Anatidae in Australia are not migratory, as they are in the Northern Hemisphere, but rather display typical nomadic traits, sometimes moving large distances across continental Australia in response to flooding or drought. There is little known regular interchange of anatids between Australia and Asia. In contrast, species such as shorebirds and some seabirds are annual migrants to Australia along recognised flyways from breeding grounds in the Northern Hemisphere. Movement into Australia by these species mainly occurs into the north-west and along the east coast over the Pacific Ocean. These species primarily arrive during the Australian spring and form large aggregations along the coastline and on inland wetlands. Other Australian migratory species (passerines, bee-eaters, dollar-birds, cuckoos, doves) regularly move to and from Asia through the Torres Strait Islands. The disease status of these birds is unknown. The movements of some species, particularly anatids and ardeids, which have ranges including Australia and regions where the virus is known to occur, have been poorly studied and there is potential for introduction of avian influenza subtypes via this route. Avian influenza viruses are highly unpredictable and can undergo reassortment to more pathogenic forms. There is insufficient knowledge of the epidemiology and transmission of these viruses in Australia and broad-scale surveillance of wild birds is logistically difficult. Long-term studies of anatids that co-habit with Charadriiformes are recommended. This would provide an indication of the spatial and temporal patterns of subtypes entering Australia and improve our understanding of the ecology of endemic viruses. Until such time as these data become available, Australia's preparedness for avian influenza must focus on biosecurity at the wild bird–poultry interface.

Effect of Phytophthora cinnamomi on the habitat utilization of Antechinus stuartii in a Victorian forest

Phytophthora cinnamomi (Cinnamon fungus) is a pathogenic soil fungus which infects plant communities along the south-eastern coast of Australia, and the south-western corner of Western Australia. The symptoms of this disease include chlorosis, death of branches (ie. ‘dieback’), retarded growth and the eventual death of infected plants. This leads to devastating effects upon plant communities by altering both the structural and floristic characteristics of these communities. Small mammal species are dependent on specific features of their habitat such as vegetation structure and floristics. This thesis investigated alterations to the habitat of the insectivorous marsupial mouse, Antechinus stuartii, due to the presence of P. cinnamomi. The study was undertaken in an area of an open forest in the Brisbane Ranges, Victoria. Significant changes were found in both the floristic composition and structure of the vegetation at study sites infected with P, cinnamomi, compared to uninfected sites. The habitat utilization by A. stuartii of uninfected and infected vegetation was investigated using live trapping and radio-telemetric techniques. Capture rates were higher at sites uninfected by P. cinnamomi, and both male and females selected areas free from infection. Home range areas of males were significantly larger than those of females as assessed by telemetry. Both sexes spent a high proportion of time in areas dominated by Xanthorrhoea australis (Austral grass tree). There were significant relationships between the abundance of A. stuartii and the denseness of vegetation above 1 metre in height, and in particular, the proportion of cover afforded by X. australis. There were no significant differences in the cover of Eucalyptus spp. between uninfected and infected sites, but there were significantly more nest hollows in infected areas. The abundance of invertebrates was examined using pitfall traps. There were no significant differences in the abundance of the larger invertebrate taxa at infected and uninfected sites, but higher abundances of some micro-invertebrate groups in infected areas were recorded. The most likely factors considered to be influential in the habitat selection of A. stuartii were vegetation structure, and the presence of X. australis. To assess whether these factors were important the leaves of X. australis were removed with a brushcutter, to mimic the early effects of infection with P. cinnamomi. Animals did not respond to the alteration of vegetation structure in the short term (3-4 days). Longer-term experiments are required to assess the habitat utilization of A. stuartii at different periods following habitat manipulation. The implications of the presence of P. cinnamomi on the conservation of fauna are discussed. The destructive nature of the pathogen, and the slow rate of recovery from the disease, means that P. cinnamomi can be considered a threatening process to plant communities and the fauna that reside within that habitat. Future management of this disease within natural areas must therefore be cognisant of the potential of P. cinnamomi to significantly affect faunal as well as vegetative communities.

The role of osmiophilic bodies and Pfg377 expression in female gametocyte emergence and mosquito infectivity in the human malaria parasite plasmodium falciparum

Osmiophilic bodies are membrane-bound vesicles, found predominantly in Plasmodium female gametocytes, that become progressively more abundant as the gametocyte reaches full maturity. These vesicles lie beneath the subpellicular membrane of the gametocyte, and the release of their contents into the parasitophorous vacuole has been postulated to aid in the escape of gametocytes from the erythrocyte after ingestion by the mosquito. Currently, the only protein known to be associated with osmiophilic bodies in Plasmodium falciparum is Pfg377, a gametocyte-specific protein expressed at the onset of osmiophilic body development. Here we show by targeted gene disruption that Pfg377 plays a fundamental role in the formation of these organelles, and that female gametocytes lacking the full complement of osmiophilic bodies are significantly less efficient both in vitro and in vivo in their emergence from the erythrocytes upon induction of gametogenesis, a process whose timing is critical for fertilization with the short-lived male gamete. This reduced efficiency of emergence explains the significant defect in oocyst formation in mosquitoes fed blood meals containing Pfg377-negative gametocytes, resulting in an almost complete blockade of infection.

A randomised trial of surgical, medical and expectant management of first trimester spontaneous miscarriage

Background: Medical management and expectant care have been considered possible alternatives to surgical evacuation of the uterus for first trimester spontaneous miscarriage in recent years.

Aim: To compare the effectiveness and safety of medical and expectant management with surgical management for first trimester incomplete or inevitable miscarriage.

Methods: Forty women were recruited following diagnosis of incomplete or inevitable miscarriage, and randomised to surgical, medical or expectant care via an off-site, computerised enrolment system. The primary outcome was the effectiveness of medical (vaginal misoprostol) and expectant management relative to surgical evacuation, assessed at 10–14 days and 8 weeks post-recruitment. Infection, pain, bleeding, anxiety, depression, physical and emotional recovery were assessed also. Analysis was by intention-to-treat.

Results: Effectiveness at 8 weeks was lower for medical (80.0%) and expectant (78.6%) than for surgical management (100.0%). Two women in the medical group had confirmed infections. Bleeding lasted longer in the expectant group than in the surgical group. There were no significant differences in pain, physical recovery, anxiety or depression between the groups. 54.6%, 42.9% and 57.1% of the surgical, medical and expectant groups respectively would opt for the same treatment again.

Conclusion: Expectant care appears to be sufficiently safe and effective to be offered as an option for women. Medical management might carry a higher risk of infection than surgical or expectant care.

Fault tolerance force for redundant manipulators

Fault tolerant manipulators maintain their trajectory even if their joint/s fails. Assuming that the manipulator is fault tolerant on its trajectory, fault tolerant compliance manipulators provide required force at their end-effector even when a joint fails. To achieve this, the contributions of the faulty joints for the force of the end-effector are required to be mapped into the proper compensating joint torques of the healthy joints to maintain the force. This paper addresses the optimal mapping to minimize the force jump due to a fault, which is the maximum effort to maintain the force when a fault occurs. The paper studies the locked joint fault/s of the redundant manipulators and it relates the force jump at the end-effector to the faults within the joints. Adding on a previous study to maintain the trajectory, in here the objective is to providing fault tolerant force at the end-effector of the redundant manipulators. This optimal mapping with minimum force jump is presented using matrix perturbation model. And the force jump is calculated through this model for single and multiple joints fault. The proposed optimal mapping is used in different fault scenarios for a 5-DOF manipulator; also it is deployed to compensate the force at the end-effector for the 5-DOF manipulator through simulation study and the results are presented.