Why initial conditions are important

Most simulation textbooks assume that a model can be started in an empty state and the final output will not be affected, so long as the "warm-up period" is excluded from the analysis. In this paper we test this assumption, using a discrete-event model of a existing manufacturing facility. Using a series of model runs with no initial Work in Progress (WIP) and another series of simulation runs with a realistic initial level of WIP, the results can be compared and contrasted. While the results show similar shaped profiles in terms of throughput and lead time, the differences between the curves has important practical implications.

Using bottlenecks to control production inventory

In this paper, we investigate how to best optimise the level of Production Inventory or Work In Progress (WIP) in a factory. Using a simulation model of the factory, we show that a level of inventory can be optimised by controlling the buffer levels of the key bottleneck workcenters. By firstly identifying the key bottlenecks, and then systematically reducing the maximum buffer level for each bottleneck, results show that the throughput does not drop rapidly from it's high levels until the WIP is halved. Conversely, the production lead time decreases rapidly and levels out around the point of the optimum WIP level.

Twitter tsunami early warning network : a social network analysis of Twitter information flows

In the aftermath of earthquakes, tsunamis, such as the 2011 Great East Japan Tsunami, caused enormous damage around the world. With the extreme disaster events of the past, nations improved disaster preparedness and response through sensors and tsunami early warning systems. Even with system usage, however, governments still need to warn the targeted citizens – who may be anywhere within the vulnerable areas – of predicted tsunami and ordered mass evacuations within a very limited lead time. While social media research is on the rise outside the domain of social networking, very little is written about Twitter use for tsunami early warning. In this research, therefore, we examined the utility of Twitter as a tsunami early warning network, which engages citizens and disaster management agencies in diffusing disaster information. We conducted a social network analysis of Twitter information flows among the central disaster warning agency’s Twitter followers during the 2012 Indonesia Earthquake.

Small-scale temporal variation in propagule supply of an intertidal red alga

Information on the variability in supply of algal propagules is scarce, hindered by the difficulty in identifying propagules, but this variability may affect the distribution and abundance of algal assemblages. This study examined the small-scale (½ hourly to hourly) temporal variation in propagule supply of Chondrus verrucosus (Gigartinaceae, Rhodophyta) over a dense, isolated bed in south-eastern Japan in summer and winter of 1999. Either 0.5 litre scoop samples or 5 litre pump samples were collected ½ hourly to hourly over 13, 22.5, and 30 h on three occasions in summer (June & July) and 32 h on one occasion in winter (December). Sampling was conducted around either the new moon (two occasions in summer) or full moon (one occasion in both summer and winter) and incorporated full tidal sequences including daytime (summer) and nighttime (winter) low-low (LL) tides. Chondrus verrucosus was the only red alga with spores within the size range of 15–20 μm that was fertile in the study area and surrounds at the time of sampling facilitating identification of spores. Spores in scoop samples were settled onto Petri dishes and identified on the basis of cell shape, colour and size. Pump samples were filtered onto transparent membrane filters and identified using epifluorescence microscopy: C. verrucosus spores fluoresced bright yellow and were easily distinguished from other micro-organisms of similar size, which fluoresced red or green. Results showed that while propagules could be found in the water column at most times, propagule supply of C. verrucosus was greatest during the 1–2 h period following LL tides. Variability in propagule supply was less than in previous studies examining surface or offshore waters. Spore release is thought to be stimulated by either desiccation or salinity changes associated with periods of emersion at low tide followed by re-immersion on incoming tides.

It's time to determine the cost of a healthy diet in Australia

Economic factors are important determinants of food security. In terms of food access, financial resources determine an individual’s ability to procure food; on the supply side, the cost of food is equally important. The interplay of these two factors, financial resources and cost, is perhaps the most immediate and important determinant of what people do (or do not) put into their shopping trolleys or purchase at the takeaway and ultimately eat – if you cannot afford it you cannot eat it even if you want to!

Identifying supply chain management and e-commerce opportunities at PaperCo Australia

Established supply chain management techniques such as Quick Response (QR) or Customer Relationship Management (CRM) have proven the potential benefits of reorganizing an organization’s processes to take advantage of the characteristics of electronic information exchange. As the Internet and other proprietary networks expand, however, organizations have the opportunity to use this enabling infrastructure to exchange other, more varied types of information than traditional electronic data interchange (EDI) messages. This is especially true of companies with global operations and interests, which lead to a more diverse set of trading activities. This case presents the experiences of a large Australian paper products manufacturer in implementing an electronic document exchange strategy for supply chain management, including the drivers for change which spurred their actions, and describes the issues associated with trying to support existing and future requirements for document exchange across a wide variety of trading partners. The experiences of PaperCo will be relevant to organizations with diverse trading partners, especially small to medium enterprises (SMEs).

Perinatal ω-3 polyunsaturated fatty acid supply modifies brain zinc homeostasis during adulthood

Dietary ω-3 polyunsaturated fatty acid (PUFA) influences the expression of a number of genes in the brain. Zinc transporter (ZnT) 3 has been identified as a putative transporter of zinc into synaptic vesicles of neurons and is found in brain areas such as hippocampus and cortex. Neuronal zinc is involved in the formation of amyloid plaques, a major characteristic of Alzheimer's disease. The present study evaluated the influence of dietary ω-3 PUFA on the expression of the ZnT3 gene in the brains of adult male Sprague-Dawley rats. The rats were raised and/or maintained on a control (CON) diet that contained ω-3 PUFA or a diet deficient (DEF) in ω-3 PUFA. ZnT3 gene expression was analyzed by using real-time PCR, free zinc in brain tissue was determined by zinquin staining, and total zinc concentrations in plasma and cerebrospinal fluid were determined by atomic absorption spectrophotometry. Compared with CON-raised animals, DEF-raised animals had increased expression of ZnT3 in the brain that was associated with an increased level of free zinc in the hippocampus. In addition, compared with CON-raised animals, DEF-raised animals had decreased plasma zinc level. No difference in cerebrospinal fluid zinc level was observed. The results suggest that overexpression of ZnT3 due to a perinatal ω-3 PUFA deficiency caused abnormal zinc metabolism in the brain. Conceivably, the influence of dietary ω-3 PUFA on brain zinc metabolism could explain the observation made in population studies that the consumption of fish is associated with a reduced risk of dementia and Alzheimer's disease.

Control of lead and trail limbs during obstacle crossing following stroke

Background and Purpose. Obstacle crossing is compromised following stroke. The purpose of this study was to quantify modifications during obstacle clearance following stroke.

Subjects. Twelve subjects with stroke and 12 subjects without stroke participated in the study.

Methods. Kinematic variables were measured while participants crossed a 4-cm-high obstacle. Subjects with stroke walked at a self-selected speed; subjects without stroke walked at a comparable speed and at a self-selected speed.

Results. Several modifications were observed following stroke with both groups walking at self-selected speeds. The affected lead limb was positioned closer to the obstacle before crossing. Affected trail-limb clearance over the obstacle was reduced. Both affected and unaffected lead and trail limbs landed closer to the obstacle after clearance. Swing time was increased in the affected lead limb after obstacle clearance. Fewer modifications were detected at matched walking speed; the trail limb still landed closer to the obstacle.

Discussion and Conclusion. Modifications during obstacle crossing following stroke may be partly related to walking speed. The findings raise issues of safety because people with stroke demonstrated reduced clearance of a 4-cm obstacle and limb placement closer to the obstacle after clearance.

Academic staff take the lead : experimenting with social software at Deakin University

This paper reports on a two staged staff development exercise to help new academic staff to integrate Web 2.0 technologies including web-based communication and some digital technologies into their curricula. It involved professional development for the teaching staff in the first stage followed by these teachers providing professional development for the course participants. The teachers engaged in a blended community of inquiry with face-to-face sessions and online work while the professional development for the course participants included technical support, training and a peer group environment with formal allocation of time for the course, finally leading to an institutionally recognised qualification. Evaluations conducted through focus group interviews revealed that collegial networks and time were important for effective professional development. The paper reflects on the successes and limitations of the model and its potential for further development. It also highlights the importance of providing professional development in a safe environment for academics to adopt technologies for teaching and learning.

Multi-agent based supply chain management with dynamic reconfiguration capability

Supply chain management (SCM) has received increased attention in a globally challenging environment as companies face the necessity to improve customer service and maximize profit. Therefore, dynamic reconfiguration capability is vital for supply chain management to respond to changing customer requirements and operating environments. On the other hand, for its flexible and autonomous characteristics, multi-agent systems are a viable technology for SCM, and have been widely applied in SCM. To this end, dynamic reconfiguration in agent-based SCM systems is proposed from autonomy oriented computing point of view. The performance of agent-based SCM with dynamic reconfiguration is evaluated under a modified TAC SCM scenario. With a dynamic reconfigurable SCM system, new products and processes can be introduced with considerably less expense and ramp-up time.

Integrity of the circadian time-keeping system in chronic fatigue syndrome

Chronic Fatigue Syndrome (CFS) is a debilitating condition in which severe, ongoing fatigue is the most prominent of a complex of somatic, psychological and neuropsychological symptoms. The aetiology of CFS remains uncertain and, to date, efforts to distinguish a clear pathophysiological profile for the disorder have been unsuccessful. Current evidence suggests that, rather than being a discrete disease entity with a single cause, CFS is a clinical condition resulting from the interaction of a number of pathophysiological factors, including acute infections, stress and psychiatric disorder. Recently, there has been some interest in the proposition that disordered circadian time-keeping may contribute to the development and/or course of the illness. The rationale for the investigation of circadian factors in CFS is based on the fact that disorders known to be associated with circadian dysregulation, such as jet lag and shiftwork related syndromes have a high degree of symptomatological overlap with CFS. Also, the presence of circadian disturbance could account, in part, for other phenomenological aspects of CFS, including the high rates of comorbid affective disturbance, and the reports of low-level immune dyregulation among sufferers. While several recent studies have produced some evidence of chronobiological dysregulation in CFS patients, much work remains before conclusions can be drawn about the presence, nature and clinical significance of circadian disturbance in CFS. This thesis describes a series of studies that were designed to systematically investigate: 1. whether CFS is associated with a state of circadian dysregulation, and 2. whether circadian dysregulation contributes significantly to the symptomatology of CFS. The first of the 5 studies reported here compared the circadian patterns of sleep-activity of CFS sufferers with those of healthy controls. Results indicated that CFS patients' sleep-activity cycles were significantly phase delayed compared to controls, and that some aspects of their circadian profiles of sleep-activity were related to some measures of sleep-disturbance and well-being. Studies 2 and 3 investigated the relationship between rhythms of sleep-wake and core temperature in CFS patients and healthy controls. The major finding from these studies was that sleep-wake and core temperature rhythms appear to be less effectively synchronised. Further evidence was collected that suggested that there was a relationship between circadian parameters and symptom measures in the CFS group. While this indicated that circadian dysregulation is linked in some way to the symptoms of CFS, assessment of the actual clinical significance of circadian disturbances required the use of a prospective methodology. The final two studies, therefore, report on a placebo-controlled trial of clinical interventions that were designed to restore circadian integrity to CFS patients, in order to see whether this would lead to a reduction in symptom number or severity. Results indicated that, although patients experienced improvements across a range of measures of symptoms and functional capacity, these were small in magnitude, of unlikely clinical significance, and no greater, in general, to improvements reported by patients who underwent placebo treatment. These results, along with those of the earlier studies, are discussed with respect to their implications regarding the presence and significance of circadian dysregulation. It is concluded that, while they provide evidence that CFS is associated with a degree of both internal and external circadian desynchrony, these findings suggest that circadian dysregulation is likely to be only a peripheral, contributor to the processes that generate and maintain the symptom complex. These findings are discussed with respect to how they contribute to our overall understanding of this multi-dimensional condition, and the implications they have for the continuing effort to investigate the causes and treatment of CFS.

A prospective study of factors that lead to body dissatisfaction during pregnancy

This study examined changes in body image and predictors of body dissatisfaction during pregnancy. It was expected that higher levels of depression, social comparison tendencies, teasing, societal pressure to be thin and public self-consciousness would predict body dissatisfaction prospectively. Healthy pregnant women (n = 128) completed questionnaires on three occasions during their pregnancies reporting on a total of four time points: 3 months prior to pregnancy (retrospectively reported), in the early to mid-second trimester, the late-second/early-third trimester, and the latter part of the third trimester. For the most part women reported adapting to the changes that occurred in their body; however, women were most likely to experience higher levels of body dissatisfaction in early to mid-second trimester. Findings related to predictors of body dissatisfaction revealed that both social and psychological factors contributed to body image changes in pregnancy. Implications of the findings are discussed.

Responsible aquaculture and trophic level implications to global fish supply

Hunger and malnutrition remain among the most devastating problems facing the world’s poor and needy, and continue to dominate the health and well-being of the world’s poorest nations. Moreover, there are growing doubts as to the long-term sustainability of many existing food production systems, including capture fisheries and aquaculture, to meet the future increasing global demands.Of the different agricultural food production systems, aquaculture (the farming of aquatic animals and plants) is widely viewed as an important weapon in the global fight against malnutrition and poverty, particularly within developing countries where over 93% of global production is currently produced, providing in most instances an affordable and a much needed source of high quality animal protein, lipids, and other essential nutrients. The current article compares for the first time the development and growth of the aquaculture sector and capture fisheries by analyzing production by mean trophic level. Whereas marine capture fisheries have been feeding the world on high trophic level carnivorous fish species since mankind has been fishing the oceans, aquaculture production within developing countries has focused, by and large, on the production of lower trophic level species. However, like capture fisheries, aquaculture focus within economically developed countries has been essentially on the culture of high value-, high trophic level-carnivorous species. The long term sustainability of these production systems is questionable unless the industry can reduce its dependence upon capture fisheries for sourcing raw materials for feed formulation and seed inputs. In line with above, the article calls for the urgent need for all countries to adopt and adhere to the principles and guidelines for responsible aquaculture of the FAO Code of Conduct for Responsible Fisheries.

The role of agregate demand and supply shocks in a low-income country : evidence from Bangladesh

This paper explores the relative role of aggregate demand and supply shocks in affecting the output level and inflation rate in a low-income country vulnerable to various economic shocks. The study uses Bangladesh data, and following Cover et al (2006), employs a modification of the Blanchard-Quah (BQ) approach, in which the two shocks are allowed to be correlated. Strong evidence is found for the hypothesis that aggregate demand and supply shocks are interrelated in Bangladesh. For the case in which causality is assumed to be running from demand to supply shocks, it was found that an independent supply shock plays significant role for fluctuations in inflation, which was absent in the standard BQ model. The results suggest that a tightening of monetary policy may lead to an adverse effect on the long-run growth potential and some supply-side policies may be required to supplement contractionary monetary policy in combating inflation in Bangladesh.