Limitations of a laboratory scale model in predicting optimal pilot scale conditions for dilute acid pretreatment of sugarcane bagasse

Pilot and industrial scale dilute acid pretreatment data can be difficult to obtain due to the significant infrastructure investment required. Consequently, models of dilute acid pretreatment by necessity use laboratory scale data to determine kinetic parameters and make predictions about optimal pretreatment conditions at larger scales. In order for these recommendations to be meaningful, the ability of laboratory scale models to predict pilot and industrial scale yields must be investigated. A mathematical model of the dilute acid pretreatment of sugarcane bagasse has previously been developed by the authors. This model was able to successfully reproduce the experimental yields of xylose and short chain xylooligomers obtained at the laboratory scale. In this paper, the ability of the model to reproduce pilot scale yield and composition data is examined. It was found that in general the model over predicted the pilot scale reactor yields by a significant margin. Models that appear very promising at the laboratory scale may have limitations when predicting yields on a pilot or industrial scale. It is difficult to comment whether there are any consistent trends in optimal operating conditions between reactor scale and laboratory scale hydrolysis due to the limited reactor datasets available. Further investigation is needed to determine whether the model has some efficacy when the kinetic parameters are re-evaluated by parameter fitting to reactor scale data, however, this requires the compilation of larger datasets. Alternatively, laboratory scale mathematical models may have enhanced utility for predicting larger scale reactor performance if bulk mass transport and fluid flow considerations are incorporated into the fibre scale equations. This work reinforces the need for appropriate attention to be paid to pilot scale experimental development when moving from laboratory to pilot and industrial scales for new technologies.

The relationship between stress, HPA axis functioning and brain structure in first episode psychosis over the first 12 weeks of treatment

Stress and abnormal hypothalamic-pituitary-adrenal axis functioning have been implicated in the early phase of psychosis and may partly explain reported changes in brain structure. This study used magnetic resonance imaging to investigate whether biological measures of stress were related to brain structure at baseline and to structural changes over the first 12 weeks of treatment in first episode patients (n=22) compared with matched healthy controls (n=22). At baseline, no significant group differences in biological measures of stress, cortical thickness or hippocampal volume were observed, but a significantly stronger relationship between baseline levels of cortisol and smaller white matter volumes of the cuneus and anterior cingulate was found in patients compared with controls. Over the first 12 weeks of treatment, patients showed a significant reduction in thickness of the posterior cingulate compared with controls. Patients also showed a significant positive relationship between baseline cortisol and increases in hippocampal volume over time, suggestive of brain swelling in association with psychotic exacerbation, while no such relationship was observed in controls. The current findings provide some support for the involvement of stress mechanisms in the pathophysiology of early psychosis, but the changes are subtle and warrant further investigation.

Developer charges and housing affordabilty in Brisbane, Australia

Purpose - This paper empirically examines the effect of developer charges on housing affordability in Brisbane, Australia. Developer paid fees or charges are a commonly used mechanism for local governments to pay for new urban infrastructure. Despite numerous government reports and many years of industry advocacy, there remains no empirical evidence in Australia to confirm or quantify passing on of these charges to home buyers. Design/methodology/approach - This research applies a hedonic house price model to 4,699 new and 25,053 existing house sales in Brisbane from 2005 to 2011. Findings – The findings of is research are consistent with international studies that support the proposition that developer charges are over passed. This study has provided evidence that suggest developer charges are over passed to both new and existing homes in the order of around 400%. Research limitations/implications - These findings suggest that developer charges are thus a significant contributor to increasing house prices and reduced housing affordability. Practical/Social Implications: By testing this effect on both new and existing homes, this research provides evidence in support of the proposition that not only are developer charges over passed to new home buyers but also to buyers of existing homes. Thus the price inflationary effect of these developer charges are being felt by all home buyers across the community, resulting in increased mortgage repayments of close to $1000 per month. Originality/value - This is the first study to empirically examine the impact of developer charges on house prices in Australia. These results are important as they will inform governments on the outcomes of growth management strategies on housing affordability, providing the first evidence of its kind in Australia.

Selectivity of human retinotopic visual cortex to S-cone-opponent, L/M-cone-opponent and achromatic stimulation

Our aim was to make a quantitative comparison of the response of the different visual cortical areas to selective stimulation of the two different cone-opponent pathways [long- and medium-wavelength (L/M)- and short-wavelength (S)-cone-opponent] and the achromatic pathway under equivalent conditions. The appropriate stimulus-contrast metric for the comparison of colour and achromatic sensitivity is unknown, however, and so a secondary aim was to investigate whether equivalent fMRI responses of each cortical area are predicted by stimulus contrast matched in multiples of detection threshold that approximately equates for visibility, or direct (cone) contrast matches in which psychophysical sensitivity is uncorrected. We found that the fMRI response across the two colour and achromatic pathways is not well predicted by threshold-scaled stimuli (perceptual visibility) but is better predicted by cone contrast, particularly for area V1. Our results show that the early visual areas (V1, V2, V3, VP and hV4) all have robust responses to colour. No area showed an overall colour preference, however, until anterior to V4 where we found a ventral occipital region that has a significant preference for chromatic stimuli, indicating a functional distinction from earlier areas. We found that all of these areas have a surprisingly strong response to S-cone stimuli, at least as great as the L/M response, suggesting a relative enhancement of the S-cone cortical signal. We also identified two areas (V3A and hMT+) with a significant preference for achromatic over chromatic stimuli, indicating a functional grouping into a dorsal pathway with a strong magnocellular input.

Mandatory reporting laws: Their origin, nature, and development over time

Dozens of countries have enacted mandatory reporting laws in various forms to respond to child abuse and neglect. Other countries including England are currently considering whether to introduce them, and if so in what form. It is important for policymakers, practitioners and researchers to understand these laws’ background, nature and purpose. This chapter outlines the origins and provenance of the first mandatory reporting laws; discusses their nature; describes major developments over time; and identifies some major effects and their consequences. It is shown that the laws are a heterogeneous, organic, flexible mechanism enabling social intervention where otherwise such intervention is severely compromised or impossible. Their primary function is to comprise but one aspect of a multifaceted child welfare system by identifying cases of serious maltreatment which would not otherwise come to light: sexual abuse and severe physical abuse are paradigm examples. The essential role of these laws is therefore primarily a tertiary aspect of a public health model, rather than a purely preventative strategy. Mandatory reporting laws are made by each specific jurisdiction according to its preferred design and function within its socio-political system. There is a spectrum of different approaches from which a jurisdiction can choose: they can apply to a broad or a narrow range of reporter groups, a broad or a narrow range of types of maltreatment, and a broad or a narrow range of instances where abuse or neglect occurs.

The new conquistadors: Patent law and expressed sequence tags

It's akin to the old Spanish, English and Portuguese explorers. They would take their boats until they found some edge of land, then they would go up and plant the flag of their king or queen. They didn't know what they'd discovered; how big it is, where it goes to - but they would claim it anyway. David Korn of the Association of American Medical Colleges This article analyses recent litigation over patent law and expressed sequence tags (ESTs). In the case of In re Fisher, the United States Court of Appeals for the Federal Circuit engaged in judicial consideration of the revised utility guidelines of the United States Patent and Trademark Office (USPTO). In this matter, the agricultural biotechnology company Monsanto sought to patent ESTs in maize plants. A patent examiner and the Board of Patent Appeals and Interferences had doubted whether the patent application was useful. Monsanto appealed against the rulings of the USPTO. A number of amicus curiae intervened in the matter in support of the USPTO - including Genentech, Affymetrix, Dow AgroSciences, Eli Lilly, the National Academy of Sciences, and the Association of American Medical Colleges. The majority of the Court of Appeals for the Federal Circuit supported the position of the USPTO, and rejected the patent application on the grounds of utility. The split decision highlighted institutional tensions over the appropriate thresholds for patent criteria - such as novelty, non-obviousness, and utility. The litigation raised larger questions about the definition of research tools, the incremental nature of scientific progress, and the role of patent law in innovation policy. The decision of In re Fisher will have significant ramifications for gene patents, in the wake of the human genome project. Arguably, the USPTO utility guidelines need to be reinforced by a tougher application of the standards of novelty and non-obviousness in respect of gene patents.

Trick or treaty?: The Australian debate over the Anti-Counterfeiting Trade Agreement

The secretive 2011 Anti-Counterfeiting Trade Agreement – known in short by the catchy acronym ACTA – is a controversial trade pact designed to provide for stronger enforcement of intellectual property rights. The preamble to the treaty reads like pulp fiction – it raises moral panics about piracy, counterfeiting, organised crime, and border security. The agreement contains provisions on civil remedies and criminal offences; copyright law and trademark law; the regulation of the digital environment; and border measures. Memorably, Susan Sell called the international treaty a TRIPS Double-Plus Agreement, because its obligations far exceed those of the World Trade Organization's TRIPS Agreement 1994, and TRIPS-Plus Agreements, such as the Australia-United States Free Trade Agreement 2004. ACTA lacks the language of other international intellectual property agreements, which emphasise the need to balance the protection of intellectual property owners with the wider public interest in access to medicines, human development, and transfer of knowledge and technology. In Australia, there was much controversy both about the form and the substance of ACTA. While the Department of Foreign Affairs and Trade was a partisan supporter of the agreement, a wide range of stakeholders were openly critical. After holding hearings and taking note of the position of the European Parliament and the controversy in the United States, the Joint Standing Committee on Treaties in the Australian Parliament recommended the deferral of ratification of ACTA. This was striking as representatives of all the main parties agreed on the recommendation. The committee was concerned about the lack of transparency, due process, public participation, and substantive analysis of the treaty. There were also reservations about the ambiguity of the treaty text, and its potential implications for the digital economy, innovation and competition, plain packaging of tobacco products, and access to essential medicines. The treaty has provoked much soul-searching as to whether the Trick or Treaty reforms on the international treaty-making process in Australia have been compromised or undermined. Although ACTA stalled in the Australian Parliament, the debate over it is yet to conclude. There have been concerns in Australia and elsewhere that ACTA will be revived as a ‘zombie agreement’. Indeed, in March 2013, the Canadian government introduced a bill to ensure compliance with ACTA. Will it be also resurrected in Australia? Has it already been revived? There are three possibilities. First, the Australian government passed enhanced remedies with respect to piracy, counterfeiting and border measures in a separate piece of legislation – the Intellectual Property Laws Amendment (Raising the Bar) Act 2012 (Cth). Second, the Department of Foreign Affairs and Trade remains supportive of ACTA. It is possible, after further analysis, that the next Australian Parliament – to be elected in September 2013 – will ratify the treaty. Third, Australia is involved in the Trans-Pacific Partnership negotiations. The government has argued that ACTA should be a template for the Intellectual Property Chapter in the Trans-Pacific Partnership. The United States Trade Representative would prefer a regime even stronger than ACTA. This chapter provides a portrait of the Australian debate over ACTA. It is the account of an interested participant in the policy proceedings. This chapter will first consider the deliberations and recommendations of the Joint Standing Committee on Treaties on ACTA. Second, there was a concern that ACTA had failed to provide appropriate safeguards with respect to civil liberties, human rights, consumer protection and privacy laws. Third, there was a concern about the lack of balance in the treaty’s copyright measures; the definition of piracy is overbroad; the suite of civil remedies, criminal offences and border measures is excessive; and there is a lack of suitable protection for copyright exceptions, limitations and remedies. Fourth, there was a worry that the provisions on trademark law, intermediary liability and counterfeiting could have an adverse impact upon consumer interests, competition policy and innovation in the digital economy. Fifth, there was significant debate about the impact of ACTA on pharmaceutical drugs, access to essential medicines and health-care. Sixth, there was concern over the lobbying by tobacco industries for ACTA – particularly given Australia’s leadership on tobacco control and the plain packaging of tobacco products. Seventh, there were concerns about the operation of border measures in ACTA. Eighth, the Joint Standing Committee on Treaties was concerned about the jurisdiction of the ACTA Committee, and the treaty’s protean nature. Finally, the chapter raises fundamental issues about the relationship between the executive and the Australian Parliament with respect to treaty-making. There is a need to reconsider the efficacy of the Trick or Treaty reforms passed by the Australian Parliament in the 1990s.

Estimating the potential impact of entry fees for marine parks on dive tourism in South East Asia

Marine reserves are increasingly being established as a mechanism to protect marine biodiversity and sensitive habitats. As well as providing conservation benefits, marine reserves provide benefits to recreational scuba divers who dive within the reserve, as well as to recreational and commercial fishers outside the reserve through spill-over effects. To ensure benefits are being realised, management of marine reserves requires ongoing monitoring and surveillance. These are not costless, and many marine reserve managers impose an entry fee. In some countries, dive tourism is major income source to coastal industries, and a concern is that high entry fees may dissuade divers. In this paper, the price elasticity of demand for dive tourism in three countries in South East Asia – Indonesia, Thailand and Malaysia – is estimated using a travel-cost model. From the model, the total non-market use value associated with diving in the area is estimated to be in the order of US$4.5 billion a year. The price elasticity of demand in the region is highly inelastic, such that increasing the cost of diving through a management levy would have little impact on total diver numbers.

Introduction to "Business innovation and disruption in the music industry"

Similar to most other creative industries, the evolution of the music industry is heavily shaped by media technologies. This was equally true in 1999, when the global recorded music industry had experienced two decades of continuous growth largely driven by the rapid transition from vinyl records to Compact Discs. The transition encouraged avid music listeners to purchase much of their music collections all over again in order to listen to their favourite music with ‘digital sound’. As a consequence of this successful product innovation, recorded music sales (unit measure) more than doubled between the early 1980s and the end of the 1990s. It was with this backdrop that the first peer-to-peer file sharing service was developed and released to the mainstream music market in 1999 by the college student Shawn Fanning. The service was named Napster and it marks the beginning of an era that is now a classic example of how an innovation is able to disrupt an entire industry and make large swathes of existing industry competences obsolete. File sharing services such as Napster, followed by a range of similar services in its path, reduced physical unit sales in the music industry to levels that had not been seen since the 1970s. The severe impact of the internet on physical sales shocked many music industry executives who spent much of the 2000s vigorously trying to reverse the decline and make the disruptive technologies go away. At the end, they learned that their efforts were to no avail and the impact on the music industry proved to be transformative, irreversible and, to many music industry professionals, also devastating. Thousands of people lost their livelihood, large and small music companies have folded or been forced into mergers or acquisitions. But as always during periods of disruption, the past 15 years have also been very innovative, spurring a plethora of new music business models. These new business models have mainly emerged outside the music industry and the innovators have been often been required to be both persuasive and persistent in order to get acceptance from the risk-averse and cash-poor music industry establishment. Apple was one such change agent that in 2003 was the first company to open up a functioning and legal market for online music. iTunes Music Store was the first online retail outlet that was able to offer the music catalogues from all the major music companies; it used an entirely novel pricing model, and it allowed consumers to de-bundle the music album and only buy the songs that they actually liked. Songs had previously been bundled by physical necessity as discs or cassettes, but with iTunes Music Store, the institutionalized album bundle slowly started to fall apart. The consequences had an immediate impact on music retailing and within just a few years, many brick and mortar record stores were forced out of business in markets across the world. The transformation also had disruptive consequences beyond music retailing and redefined music companies’ organizational structures, work processes and routines, as well as professional roles. iTunes Music Store in one sense was a disruptive innovation, but it was at the same time relatively incremental, since the major labels’ positions and power structures remained largely unscathed. The rights holders still controlled their intellectual properties and the structures that guided the royalties paid per song that was sold were predictable, transparent and in line with established music industry practices.

A comparative study of multiple attribute tree and inverted file structures for large bibliographic files

A variety of data structures such as inverted file, multi-lists, quad tree, k-d tree, range tree, polygon tree, quintary tree, multidimensional tries, segment tree, doubly chained tree, the grid file, d-fold tree. super B-tree, Multiple Attribute Tree (MAT), etc. have been studied for multidimensional searching and related problems. Physical data base organization, which is an important application of multidimensional searching, is traditionally and mostly handled by employing inverted file. This study proposes MAT data structure for bibliographic file systems, by illustrating the superiority of MAT data structure over inverted file. Both the methods are compared in terms of preprocessing, storage and query costs. Worst-case complexity analysis of both the methods, for a partial match query, is carried out in two cases: (a) when directory resides in main memory, (b) when directory resides in secondary memory. In both cases, MAT data structure is shown to be more efficient than the inverted file method. Arguments are given to illustrate the superiority of MAT data structure in an average case also. An efficient adaptation of MAT data structure, that exploits the special features of MAT structure and bibliographic files, is proposed for bibliographic file systems. In this adaptation, suitable techniques for fixing and ranking of the attributes for MAT data structure are proposed. Conclusions and proposals for future research are presented.

Environmental change and human history in the Jabal Harun area, Jordan

The research is related to the Finnish Jabal Harun Project (FJHP), which is part of the research unit directed by Professor Jaakko Frösén. The project consists of two interrelated parts: the excavation of a Byzantine monastery/pilgrimage centre on Jabal Harun, and a multiperiod archaeological survey of the surrounding landscape. It is generally held that the Near Eastern landscape has been modified by millennia of human habitation and activity. Past climatic changes and human activities could be expected to have significantly changed also the landscape of the Jabal Harun area. Therefore it was considered that a study of erosion in the Jabal Harun area could shed light on the environmental and human history of the area. It was hoped that it would be possible to connect the results of the sedimentological studies either to wider climatic changes in the Near East, or to archaeologically observable periods of human activity and land use. As evidence of some archaeological periods is completely missing from the Jabal Harun area, it was also of interest whether catastrophic erosion or unfavourable environmental change, caused either by natural forces or by human agency, could explain the gaps in the archaeological record. Changes in climate and/or land-use were expected to be reflected in the sedimentary record. The field research, carried out as part of the FJHP survey fieldwork, included the mapping of wadi terraces and cleaning of sediment profiles which were recorded and sampled for laboratory analyses of facies and lithology. To obtain a chronology for the sedimentation and erosion phases also OSL (optically stimulated luminescence) dating samples were collected. The results were compared to the record of the Near Eastern palaeoclimate, and to data from geoarchaeological studies in central and southern Jordan. The picture of the environmental development was then compared to the human history in the area, based on archaeological evidence from the FJHP survey and the published archaeological research in the Petra region, and the question of the relationship between human activity and environmental change was critically discussed. Using the palaeoclimatic data and the results from geoarchaeological studies it was possible to outline the environmental development in the Jabal Harun area from the Pleistocene to the present.It is appears that there was a phase of accumulation of sediment before the Middle Palaeolithic period, possibly related to tectonic movement. This phase was later followed by erosion, tentatively suggested to have taken place during the Upper Palaeolithic. A period of wadi aggradation probably occurred during the Late Glacial and continued until the end of the Pleistocene, followed by significant channel degradation, attributed to increased rainfall during the Early Holocene. It seems that during the later Holocene channel incision has been dominant in the Jabal Harûn area although there have been also small-scale channel aggradation phases, two of which were OSL-dated to around 4000-3000 BP and 2400-2000 BP. As there is no evidence of tectonic movements in the Jabal Harun area after the early Pleistocene, it is suggested that climate change and human activity have been the major causes of environmental change in the area. At a brief glance it seems that many of the changes in the settlement and land use in the Jabal Harun area can be explained by climatic and environmental conditions. However, the responses of human societies to environmental change are dependent on many factors. Therefore an evaluation of the significance of environmental, cultural, socio-economic and political factors is needed to decide whether certain phenomena are environmentally induced. Comparison with the wider Petra region is also needed to judge whether the phenomena are characteristic of the Jabal Harun area only, or can they be connected to social, political and economic development over a wider area.

The performance of strawberry plugs in Queensland

Plugs or containerized plants can offer several advantages over traditional bare-rooted runner plants for strawberry (Fragaria x ananassa) production. Some of these benefits include easier planting, better establishment, fewer pests and diseases, and lower water use during plant establishment resulting in less leaching of applied fertilizers. Plugs also offer the potential for mechanical planting. In some areas of Europe and North America, plugs provide earlier production, greater productivity and larger fruit than runners. Research has also shown that the plants can be grown under short days and low temperatures to manipulate flower initiation and fruiting. Plugs are more expensive to buy compared with runner plants, and will only be adopted by industry if the extra costs are matched by convenience, resource conservation, increased fruiting and returns to producers. We investigated the productivity of 'Festival' and 'Sugarbaby' propagated as plugs (75 cm3 containers) and runners from Stanthorpe in southern Queensland (elevation of 872 m), and grown at Nambour on the Sunshine Coast (elevation 29 m). At planting, the plug plants weighed 0.8 ± 0.1 g DW compared with 53 ± 0.5 g DW for the runner plants. 'Sugarbaby' plugs were larger than 'Festival' plugs (33 ± 0.6 g versus 2.9 ± 0.6 g). The differences in growth at planting were maintained until the third week of July (day 94), with the plug plants weighing 17.8 ± 2.2 g, and the runner plants 21.4 ± 23 g. The proportion of plant dry matter allocated to the leaves increased over time from 59 to 70%, while the proportion allocated to the roots decreased from 21 to 10%. Harvest commenced after 60 days, with the plug plants yielding only 60% of the yields of the runner plants up until 8 August or day 109 (14.2 ± 1.4 g plant -1 week-1 versus 23.6 ± 1.9 g plant-1 week-1). 'Festival' (22.2 ± 2.0 g plant-1 week -1) had higher yields than 'Sugarbaby' (15.5 ± 1.5 g plant-1 week-1), even though plants of the latter were larger. Average fruit weight was 15.6 ± 0.3 g, with no effect of cultivar, plant type or harvest time. In other words, the differences in yield between the various treatments were due to differences in fruit set The lower yields of the plug plants probably reflect their small size at planting. Future research should determine whether plugs grown in larger cells (150 to 300 cm3 as in the USA and Europe) are more productive. Tips to be grown in larger containers should be harvested earlier than those for small cells to maximize root growth of the plug plant. This will probably extend the time required from harvest of the tips and potting them from the current four to five weeks, to eight to ten weeks.

Effects of environmental heat on conception rates in lactating dairy cows: Critical periods of exposure

Environmental heat can reduce conception rates (the proportion of services that result in pregnancy) in lactating dairy cows. The study objectives were to identify periods of exposure relative to the service date in which environmental heat is most closely associated with conception rates, and to assess whether the total time cows are exposed to high environmental heat within each 24-h period is more closely associated with conception rates than is the maximum environmental heat for each 24-h period. A retrospective observational study was conducted in 25 predominantly Holstein-Friesian commercial dairy herds located in Australia. Associations between weather and conception rates were assessed using 16,878 services performed over a 21-mo period. Services were classified as successful based on rectal palpation. Two measures of heat load were defined for each 24-h period: the maximum temperature-humidity index (THI) for the period, and the number of hours in the 24-h period when the THI was >72. Conception rates were reduced when cows were exposed to a high heat load from the day of service to 6 d after service, and in wk -1. Heat loads in wk -3 to -5 were also associated with reduced conception rates. Thus, management interventions to ameliorate the effects of heat load on conception rates should be implemented at least 5 wk before anticipated service and should continue until at least 1 wk after service. High autocorrelations existed between successive daily values in both measures, and associations between day of heat load relative to service day and conception rates differed substantially when ridge regression was used to account for this autocorrelation. This indicates that when assessing the effects of heat load on conception rates, the autocorrelation in heat load between days should be accounted for in analyses. The results suggest that either weekly averages or totals summarizing the daily heat load are adequate to describe heat load when assessing effects on conception rates in lactating dairy cows.

Weed eradication - an economic perspective

There has been recent interest in determining the upper limits to the feasibility of weed eradication. Although a number of disparate factors determine the success of an eradication program, ultimately eradication feasibility must be viewed in the context of the amount of investment that can be made. The latter should reflect the hazard posed by an invasion, with greater investment justified by greater threats. In simplest terms, the effort (and hence investment) to achieve weed eradication comprises the detection effort required to delimit an invasion plus the search and control effort required to prevent reproduction until extirpation occurs over the entire infested area. The difficulty of estimating the required investment at the commencement of a weed eradication program (as well as during periodic reviews) is a serious problem. Bioeconomics show promise in determining the optimal approach to managing weed invasions, notwithstanding ongoing difficulties in estimating the costs and benefits of eradication and alternative invasion management strategies. A flexible approach to the management of weed invasions is needed, allowing for the adoption of another strategy when it becomes clear that the probability of eradication is low, owing to resourcing or intractable technical issues. Whether the considerable progress that has been achieved towards eradication of the once massive witchweed invasion can be duplicated for other weeds of agricultural systems will depend to a large extent upon investment (. $250 million over 50 yr in this instance). Weeds of natural ecosystems seem destined to remain more difficult eradication targets for a variety of reasons, including higher impedance to eradication, more difficulty in valuing the benefits arising from eradication, and possibly less willingness to pay from society at large.

Estimating and influencing the duration of weed eradication programmes

1. Weed eradication efforts often must be sustained for long periods owing to the existence of persistent seed banks, among other factors. Decision makers need to consider both the amount of investment required and the period over which investment must be maintained when determining whether to commit to (or continue) an eradication programme. However, a basis for estimating eradication programme duration based on simple data has been lacking. Here, we present a stochastic dynamic model that can provide such estimates. 2. The model is based upon the rates of progression of infestations from the active to the monitoring state (i.e. no plants detected for at least 12 months), rates of reversion of infestations from monitoring to the active state and the frequency distribution of time since last detection for all infestations. Isoquants that illustrate the combinations of progression and reversion parameters corresponding to eradication within different time frames are generated. 3. The model is applied to ongoing eradication programmes targeting branched broomrape Orobanche ramosa and chromolaena Chromolaena odorata. The minimum periods in which eradication could potentially be achieved were 22 and 23 years, respectively. On the basis of programme performance until 2008, however, eradication is predicted to take considerably longer for both species (on average, 62 and 248 years, respectively). Performance of the branched broomrape programme could be best improved through reducing rates of reversion to the active state; for chromolaena, boosting rates of progression to the monitoring state is more important. 4. Synthesis and applications. Our model for estimating weed eradication programme duration, which captures critical transitions between a limited number of states, is readily applicable to any weed.Aparticular strength of the method lies in its minimal data requirements. These comprise estimates of maximum seed persistence and infested area, plus consistent annual records of the detection (or otherwise) of the weed in each infestation. This work provides a framework for identifying where improvements in management are needed and a basis for testing the effectiveness of alternative tactics. If adopted, our approach should help improve decision making with regard to eradication as a management strategy.