List of Titles

A data mining application of the incidence semirings

- Abawajy, Jemal, Kelarev, Andrei, Yearwood, John, Turville, Christopher

Authors: Abawajy, Jemal , Kelarev, Andrei , Yearwood, John , Turville, Christopher
Date: 2013
Type: Text , Journal article
Relation: Houston Journal of Mathematics Vol. 39, no. 4 (2013), p. 1083-1093
Relation: http://purl.org/au-research/grants/arc/LP0990908
Full Text: false
Reviewed:
Description: This paper is devoted to a combinatorial problem for incidence semirings, which can be viewed as sets of polynomials over graphs, where the edges are the unknowns and the coefficients are taken from a semiring. The construction of incidence rings is very well known and has many useful applications. The present article is devoted to a novel application of the more general incidence semirings. Recent research on data mining has motivated the investigation of the sets of centroids that have largest weights in semiring constructions. These sets are valuable for the design of centroid-based classification systems, or classifiers, as well as for the design of multiple classifiers combining several individual classifiers. Our article gives a complete description of all sets of centroids with the largest weight in incidence semirings.

Amaranthus retroflexus L (redroot pigweed) : effects of elevated CO2 and soil moisture on growth and biomass and the effect of radiant heat on seed germination

- Weller, Sandra, Florentine, Singarayer, Welgama, Amali, Chadha, Aakansha, Turville, Christopher

Authors: Weller, Sandra , Florentine, Singarayer , Welgama, Amali , Chadha, Aakansha , Turville, Christopher
Date: 2021
Type: Text , Journal article
Relation: Agronomy Vol. 11, no. 4 (2021), p.
Full Text:
Reviewed:
Description: Amaranthus retroflexus L. (Amaranthaceae), Redroot pigweed, is native to North America, but has become a weed of agriculture worldwide. Previous research into competition with food crops found it significantly reduces yields. Additionally, taxonomy, biomass allocation, physiological responses to light intensity, water stress, elevated CO2, and herbicide resistance have been inves-tigated. To extend other research findings, we investigated growth and biomass yield in response to (i) soil moisture stress, and (ii) drought and elevated CO2. Additionally, we investigated seed germination rates following exposure to three elevated temperatures for two different time periods. Overall, moisture stress reduced plant height, stem diameter, and number of leaves. Elevated CO2 (700 ppm) appeared to reduce negative impacts of drought on biomass productivity. Heating seeds at 120◦C and above for either 180 or 300 s significantly reduced germination rate. These results inform an understanding of potential responses of A. retroflexus to future climate change and will be used to predict future occurrence of this weed. The finding that exposing seeds to high temperatures retards germination suggests fire could be used to prevent seed germination from soil seed banks, particularly in no-till situations, and therefore may be used to address infestations or prevent further spread of this weed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliates “Sandra Weller, Singarayer Florentine, Amali Welgama, Aakansha Chadha, Chrisopher Turville" are provided in this record**

Quick View

An integrated approach for the restoration of Australian temperate grasslands invaded by Nassella trichotoma

- Humphries, Talia, Turville, Christopher, Sinclair, Steven, Florentine, Singarayer

Authors: Humphries, Talia , Turville, Christopher , Sinclair, Steven , Florentine, Singarayer
Date: 2022
Type: Text , Journal article
Relation: Scientific Reports Vol. 12, no. 1 (2022), p.
Full Text:
Reviewed:
Description: Invasive plants are considered to be one of the biggest threats to environmental assets, and once established, they can be immensely difficult to control. Nassella trichotoma is an aggressive, perennial grass species, and is considered to be one of the most economically damaging weeds to grazing systems due to its unpalatability, as well as being one of the leading causes of biodiversity loss in grassland communities. This species produces high density seedbanks that rapidly respond to disturbance events. Despite control programs being developing in Australia since the 1930s, this species is still widespread throughout south-east Australia, indicating that a new management approach is critical to control this Weed of National Significance at the landscape scale. The present study explored the effect of 12 different combinations of herbicide, fire, a second application of herbicide, grazing exclusion, tillage and broadcasting seeds in order to reduce the above and below-ground density of N. trichotoma. A control treatment was also included. The results were assessed using a Hierarchy analysis, whereby treatments of increasing complexity were compared for their efficacy in reducing N. trichotoma cover and seedbank density, while simultaneously increasing the establishment of the broadcast species. Whilst all integrated treatments effectively reduced N. trichotoma’s seedbank, the treatments that included fire performed significantly better at simultaneously reducing N. trichotoma and increasing the establishment of broadcasted seeds. Overall, the integration of herbicide, fire and broadcasting native seeds was observed to provide the most economically feasible management strategy for the landscape scale restoration of a degraded temperate grassland dominated by N. trichotoma. © 2022, The Author(s).

Quick View

Assessing seed longevity of the Invasive Weed Navua Sedge (Cyperus aromaticus), by artificial ageing

- Chadha, Aakansha, Florentine, Singarayer, Dhileepan, Kunjithapatham, Turville, Christopher

Authors: Chadha, Aakansha , Florentine, Singarayer , Dhileepan, Kunjithapatham , Turville, Christopher
Date: 2022
Type: Text , Journal article
Relation: Plants Vol. 11, no. 24 (2022), p.
Full Text:
Reviewed:
Description: Navua sedge (Cyperus aromaticus (Ridley) Mattf. & Kukenth) is a significant agricultural and environmental weed found in tropical island countries including north Queensland, Australia. It is a prolific seed producer and consequently forms a high-density seedbank, and therefore understanding the longevity and persistence of the seeds can provide critical information required for the management of this species. A laboratory-controlled artificial ageing experiment was conducted where the seeds were exposed to a temperature of 45 °C and 60% relative humidity for 125 days. Seeds were removed at various times (1, 2, 5, 9, 20, 30, 50, 75, 100 and 125 days) and their viability determined through standard germination tests. It took 20 days in the artificial ageing environment for the seeds to decline to 50% viability which indicates that Navua sedge has relatively short-lived persistent seeds. These findings will assist in developing a better understanding of the seedbank dynamics of this invasive species, allowing managers to tactically implement control strategies and prepare budgets for ongoing treatments, and have implications for the duration and success of management programs. © 2022 by the authors.

Quick View

Changes of names, contents and attitudes to mathematical units

- Turville, Christopher, Pierce, Robyn, Barker, Ewan, Giri, Jason

Authors: Turville, Christopher , Pierce, Robyn , Barker, Ewan , Giri, Jason
Date: 2002
Type: Text , Conference paper
Relation: Paper presented at the 2nd International Conference on the Teaching of Mathematics, Crete, Greece : 1st June, 2003
Full Text:
Reviewed:
Description: Will this material be on the exam? Why do I need to know this stuff? These are the sorts of questions that have been regularly asked by our mathematics students. Pre-service mathematics teachers often suggest that they do not need to learn anything that they do not have to teach. Generally, these students appear to have very little aesthetic appreciation for mathematics and its applications. Currently, we teach five traditional mathematical content units that are provided mainly for pre-service mathematics teachers. These units have been adapted and modified over the years from units that were designed primarily for science students. They contained a heavy focus on calculus with a limited breadth of mathematical experience. After consulting widely on the best mathematical practices throughout Australia and internationally, it was decided to reform all of the mathematics units to make them more attractive to a wider audience. The units that are currently being developed are: Profit, Loss and Gambling; Upon the Shoulders of Giants; Logic and Imagination; Modelling and Change; Algorithms, Bits and Bytes; Space, Shape, and Design; and Modelling Reality. The overall goal of this redevelopment is to improve student attitudes and motivation by exposing them to a wide range of topics in mathematics that are usable and relevant. All of these units will incorporate current technology, contain realistic problems, and include visiting speakers. Student assessment in these units will consist of portfolios, projects and examinations. The introduction of these new units will result in students having a greater choice of the units they wish to study. In order to overcome potential logistical problems of a small mathematics department, innovative changes to the structure of the units will also be examined. This paper will provide the details of the establishment and content of these units.
Description: E1
Description: 2003000085

Data mining of the Australian adverse drug reactions database : A comparison of Bayesian and other statistical indicators

- Harvey, Jack, Turville, Christopher, Barty, Simon

Authors: Harvey, Jack , Turville, Christopher , Barty, Simon
Date: 2004
Type: Text , Journal article
Relation: International Transactions in Operational Research Vol. 11, no. (2004), p. 419-433
Full Text: false
Reviewed:
Description: The Australian adverse drug reactions database is derived from 140,000 reports over 30 years, including many instances of multiple drugs and multiple reactions. There are several thousand different drugs and reactions, and so the drug-reaction table is large and sparse. To aid rapid expert assessment of new reports, Bayesian approaches are being compared with other statistical methods for the re-evaluation of historical data and to provide early indications of emerging trends. Bayesian methods provide more balanced detection criteria than either descriptive statistics such as relative risks, which are subject to large sampling variation for rare co-occurrences, or statistical significance levels which are conversely weighted towards the most common co-occurrences. In this paper the various methods are reviewed and some indicative early results are presented.
Description: C1
Description: 2003000879

Detection and verification of tropical cyclones and depressions over the South Pacific Ocean basin using ERA-5 reanalysis dataset

- Yeasmin, Alea, Chand, Savin, Turville, Christopher, Sultanova, Nargiz

Authors: Yeasmin, Alea , Chand, Savin , Turville, Christopher , Sultanova, Nargiz
Date: 2021
Type: Text , Journal article
Relation: International Journal of Climatology Vol. 41, no. 11 (2021), p. 5318-5330
Full Text: false
Reviewed:
Description: Tropical cyclones (TCs) are one of the most destructive synoptic systems and can cause enormous loss of life and property damages in the South Pacific island nations. The impact of tropical depressions (TDs, i.e. weaker systems that do not develop into TCs) can also be staggering in the region in terms of heavy flooding and landslides, but a lack of complete records often hinders research involving TD impacts. A methodology has been developed here to detect TDs in the ERA-5 reanalysis dataset (the fifth generation ECMWF atmospheric reanalysis of the global climate) using the Okubo–Weiss–Zeta parameter (OWZP) detection scheme. The new South Pacific Enhanced Archive for Tropical Cyclones dataset (SPEArTC), the Dvorak analysis of satellite-based cloud patterns over the South Pacific Ocean basin, and a rainfall dataset for various stations and historical archives have been utilized to validate ERA5-derived TCs and TDs for the period between 1979 and 2019. Results indicate that the OWZP method shows substantial skill in capturing the realistic climatological distribution of TDs (as well as TCs) for the South Pacific Ocean in the ERA5 reanalysis, paving a way forward for future climatological studies involving the impacts of TCs and TDs over the island nations using longer-term reanalyses products such as the 20th-century reanalysis dataset that extends back to the 1850s. © 2021 Royal Meteorological Society

Quick View

Does climate play any role in covid-19 spreading? : an Australian perspective

- Abraham, Joji, Turville, Christopher, Dowling, Kim, Florentine, Singarayer

Authors: Abraham, Joji , Turville, Christopher , Dowling, Kim , Florentine, Singarayer
Date: 2021
Type: Text , Journal article
Relation: International Journal of Environmental Research and Public Health Vol. 18, no. 17 (2021), p.
Full Text:
Reviewed:
Description: Compared to other countries, the COVID-19 pandemic did not severely affect Australia as measured by total deaths until mid-2021. Though a substantial number of daily confirmed cases (up to 698) were reported during the second wave, most of them were from the southern state of Victoria. This study examined the possible correlations between climate variables and the number of daily confirmed COVID-19 cases in Victoria, Australia, from 25 January to 31 October 2020. Appropriate regression models and cross-correlation diagnostics were used to examine the effect of temperature, rainfall, solar exposure, and ultraviolet index (UVI) with the number of daily confirmed cases. Significant positive associations were identified for solar exposure and maximum and average UVI for confirmed cases one and 19 days later. Negative associations for these variables were found for confirmed cases five days later. Minimum temperature had a significant negative correlation one day later and a positive effect 21 days later. No significant correlation was found for maximum temperature and rainfall. The most significant relationships were found for confirmed cases 19 days after changes in the meteorological variables. A 1% increase in solar exposure, maximum UVI, and average UVI was associated with a 0.31% (95% CI: 0.13 to 0.51), 0.71% (95% CI: 0.43 to 0.98), and 0.63% (95%CI: 0.20 to 1.61) increase 19 days later in the number of confirmed cases, respectively. The implications of these results can be used in the public health management of any possible future events in Australia. It also highlights the significance of considering the climatic variables and seasonality in all kinds of epidemics and pandemics. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Eastern North Pacific tropical cyclone activity in historical and future CMIP5 experiments : Assessment with a model-independent tracking scheme

- Bell, Samuel, Chand, Savin, Tory, Kevin, Turville, Christopher, Ye, Harvey

Authors: Bell, Samuel , Chand, Savin , Tory, Kevin , Turville, Christopher , Ye, Harvey
Date: 2019
Type: Text , Journal article
Relation: Climate Dynamics Vol. 53, no. 7-8 (2019), p. 4841-4855
Full Text: false
Reviewed:
Description: The sensitivity of tropical cyclone (TC) projection results to different models and the detection and tracking scheme used is well established in the literature. Here, future climate projections of TC activity in the Eastern North Pacific basin (ENP, defined from 0 degrees to 40 degrees N and 180 degrees to similar to 75 degrees W) are assessed with a model- and basin-independent detection and tracking scheme that was trained in reanalysis data. The scheme is applied to models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) experiments forced under the historical and Representative Concentration Pathway 8.5 (RCP8.5) conditions. TC tracks from the observed records and models are analysed simultaneously with a curve-clustering algorithm, allowing observed and model tracks to be projected onto the same set of clusters. The ENP is divided into three clusters, one in the Central North Pacific (CNP) and two off the Mexican coast, as in prior studies. After accounting for model biases and auto-correlation, projection results under RCP8.5 indicated TC genesis to be significantly suppressed east of 125 degrees W, and significantly enhanced west of 145 degrees W by the end of the twenty-first century. Regional TC track exposure was found to significantly increase around Hawaii (similar to 86%), as shown in earlier studies, owing to increased TC genesis, particularly to the south-east of the island nation. TC exposure to Southern Mexico was shown to decrease (similar to 4%), owing to a south-westward displacement of TCs and overall suppression of genesis near the Mexican coastline. The large-scale environmental conditions most consistent with these projected changes were vertical wind shear and relative humidity.

Ecology, distribution and control of the invasive weed Nassella trichotoma (Nees) Hack. ex Arechav. : a global review of current and future challenges

- Humphries, Talia, Dowling, Kim, Turville, Christopher, Sinclair, Steve, Florentine, Singarayer

Authors: Humphries, Talia , Dowling, Kim , Turville, Christopher , Sinclair, Steve , Florentine, Singarayer
Date: 2020
Type: Text , Journal article , Review
Relation: Weed Research Vol. 60, no. 6 (2020), p. 392-405
Full Text: false
Reviewed:
Description: Nassella trichotoma (serrated tussock) is a highly invasive perennial C3 weed from South America. It grows in most soil conditions, can resist fire and frost, and is unpalatable to grazing animals. Each plant can produce up to 140,000 seeds annually, and together, these characteristics make it a damaging landscape weed. It has diminished the agricultural carrying capacity of pastures in south-eastern Australia, New Zealand and South Africa, and emerging populations have now been identified in Europe and the United States, and bioclimatic models suggest its distribution could significantly expand within these regions in the near future. Research into control methods for this weed has been explored, and these include herbicides applied alone and in combination, the establishment of plant competition, the introduction of seed mitigation fencing, grazing management and exclusion zones, specific biological management and alteration of soil composition. Currently, the most effective and widely used control method is the residual herbicide flupropanate (2,2,3,3-tetrafluoropropanoic acid). This review will investigate the ecology, distribution, current control techniques and past research on this species, and make recommendations for future research and management. © 2020 European Weed Research Society

Quick View

Effect of Rhizome Fragment Length and Burial Depth on the emergence of a tropical invasive Weed Cyperus aromaticus (Navua Sedge)

- Chadha, Aakansha, Florentine, Singarayer, Dhileepan, Kunjithapatham, Turville, Christopher

Authors: Chadha, Aakansha , Florentine, Singarayer , Dhileepan, Kunjithapatham , Turville, Christopher
Date: 2022
Type: Text , Journal article
Relation: Plants Vol. 11, no. 23 (2022), p.
Full Text:
Reviewed:
Description: Cyperus aromaticus (Navua sedge) is a problematic perennial weed in pastures and crops including sugarcane, banana, rice, and fruits and vegetables in tropical climates. It reproduces both via rhizomes and seeds. As a regenerative and storage organ, these rhizomes play an important part in the invasion, establishment, and persistence of this weed. To eliminate their regenerative ability, it is important to understand the regrowth potential with respect to rhizome fragment size and burial depth. This study evaluated the emergence of C. aromaticus from rhizomes in a controlled condition. Three different sizes of rhizome fragments were buried at seven depths of up to 20 cm in two soil types. The experimental measurements included (i) the time for tillers to emerge, (ii) the cumulative emergence of tillers, recorded weekly, and (iii) the number of underground emerging tillers. The cumulative shoot emergence and the number of underground tillers produced were found to be positively correlated with the initial length of the rhizome fragments and negatively correlated with the burial depth. The time for the emergence of the tillers was negatively correlated with the burial depth, and soil type had no significant effect on any of the parameters recorded. There was no emergence recorded from rhizomes buried at 15 cm depth and deeper, irrespective of their size. Our results indicate that the combination of the fragmentation of rhizomes into small pieces and a deep burial, below 15 cm, is an important aspect to control the regeneration of C. aromaticus from rhizomes, if tillage is carried out, and can therefore form a part of an integrated weed management strategy for this troublesome weed. © 2022 by the authors.

Efficacy of halosulfuron-methyl in the management of Navua sedge (Cyperus aromaticus) : differential responses of plants with and without established rhizomes

- Chadha, Aakansha, Florentine, Singarayer, Dhileepan, Kunjithapatham, Turville, Christopher, Dowling, Kim

Authors: Chadha, Aakansha , Florentine, Singarayer , Dhileepan, Kunjithapatham , Turville, Christopher , Dowling, Kim
Date: 2022
Type: Text , Journal article
Relation: Weed Technology Vol. 36, no. 3 (2022), p. 397-402
Full Text: false
Reviewed:
Description: Navua sedge is a creeping perennial sedge commonly found in tropical environments and is currently threatening many agroecosystems and ecosystems in Pacific Island countries and northern Queensland, Australia. Pasture and crop productions have been significantly impacted by this weed. The efficacy of halosulfuron-methyl on Navua sedge plants with and without well-established rhizomes was evaluated under glasshouse conditions. Halosulfuron-methyl was applied to plants with established rhizomes at three stages; mowed, pre-flowering, and flowering growth stages, whereas plants without established rhizomes were treated at seedling, pre-flowering and flowering growth stages. At each application time, halosulfuron-methyl was applied at four dose rates of 0, 38, 75, and 150 g ai ha-1. Mortality of 27.5%, 0%, and 5% was recorded in rhizomatous Navua sedge when treated with 75 g ai ha-1 of halosulfuron-methyl at the mowed, pre-flowering stage and flowering stages, respectively. At 10 wk after treatment (WAT), there were no tillers in surviving plants treated at any of the application times. By 16 WAT, the number of tillers increased to 15, 24, and 26 in mowed, pre-flowering, and flowering stages, respectively. Although halosulfuron-methyl is effective in controlling aboveground growth, subsequent emergence of new growth from the rhizome confirms the failure of the herbicide to kill the rhizome. Application of 75 g ai ha-1 of halosulfuron-methyl provided 100% mortality in plants treated at seedling and pre-flowering stages, and 98% mortality when treated at flowering stage in non-rhizomatous plants. A single application of halosulfuron-methyl is highly effective at controlling Navua sedge seedlings but not effective at controlling plants with established rhizomes. © 2022 Cambridge University Press. All rights reserved.

Environmental factors affecting the germination and seedling emergence of two populations of an emerging agricultural weed : Wild lettuce (Lactuca serriola)

- Chadha, Aakansha, Florentine, Singarayer, Chauhan, Bhagirath, Long, Benjamin, Jayasundera, Mithila, Javaid, Muhammad, Turville, Christopher

Authors: Chadha, Aakansha , Florentine, Singarayer , Chauhan, Bhagirath , Long, Benjamin , Jayasundera, Mithila , Javaid, Muhammad , Turville, Christopher
Date: 2019
Type: Text , Journal article
Relation: Crop and Pasture Science Vol. 70, no. 8 (2019), p. 709-717
Full Text: false
Reviewed:
Description: Wild lettuce (Lactuca serriola L.) is a significant emerging agricultural and environmental weed in many countries. This invasive species is now naturalised in Australia and is claimed to cause significant losses within the agricultural industry. Sustainable management of wild lettuce has been hampered by a lack of detailed knowledge of its seed ecology. Laboratory-based studies were performed to examine the potential influence of environmental factors including temperature and light conditions, salinity, pH, moisture availability and burial depth on the germination and emergence of two spatially distant populations of wild lettuce. Results suggested that the germination of wild lettuce seeds occurred across a broad range of temperature conditions (12-h cycle: 30°C/20°C, 25°C/15°C and 17°C/7°C) for both populations. We also found that these seeds are non-photoblastic germination was not affected by darkness, with >80% germination in darkness for both populations at all tested temperature ranges. Germination significantly declined as salinity and osmotic stress increased for both populations, with seeds from the Tempy population were more affected by NaCl >100 mM than seeds from Werribee, but in neither population was there any observed effect of pH on germination (>80% germination in both populations at all tested pH ranges). For both populations, germination significantly decreased as burial depth increased however, the two populations differed with regard to response to burial depth treatment, whereby seeds from the Tempy population had higher emergence than those from Werribee at 0.5 cm burial depth. These results suggest that light-reducing management techniques such as mulching or use of crop residues will be unsuccessful for preventing germination of wild lettuce. By contrast, burial of seeds at a depth of at least 4 cm will significantly reduce their emergence.

Quick View

Evaluation of Florpyrauxifen-Benzyl for the control of Cyperus aromaticus (Navua sedge)

- Chadha, Aakansha, Florentine, Singarayer, Dhileepan, Kunjithapatham, Turville, Christopher, Dowling, Kim

Authors: Chadha, Aakansha , Florentine, Singarayer , Dhileepan, Kunjithapatham , Turville, Christopher , Dowling, Kim
Date: 2022
Type: Text , Journal article
Relation: Advances in Weed Science Vol. 40, no. (2022), p.
Full Text:
Reviewed:
Description: Background: Cyperus aromaticus (Navua sedge) is a creeping perennial sedge common to tropical environments, currently threatening many agroecosystems and ecosystems in Pacific Island countries and northern Queensland in Australia. Objective: A glasshouse study was conducted to evaluate the efficacy of florpyrauxifen-benzyl on C. aromaticus plants with and without established rhizomes. Methods: The plants with established rhizomes were treated at three application times being mowed, pre-flowering and flowering growth stages and plants without established rhizomes were treated at seedling, pre-flowering and flowering growth stages. At each application time, plants were treated with four rates of florpyrauxifen-benzyl: 0, 15, 30 and 60 g a.i. ha-1 and control. Results: There was no mortality in the plants with established rhizomes. Reduction in the number of tillers was observed at four weeks after treatment (WAT) in plants treated with 30 and 60 g a.i. ha-1 of herbicide, however, there was new growth from the rhizomes and the number of tillers increased at 8 WAT. Conversely, florpyrauxifen-benzyl provided above 95% control in plants without established rhizomes. Conclusions: These results indicate florpyrauxifen-benzyl can help manage a new C. aromaticus infestation prior to the establishment of rhizomes. However, it has little to no impact on C. aromaticus plants with established rhizomes, and other management options should be employed to control them. © 2022, Sociedade Brasileira da Ciencia das Plantas Daninha. All rights reserved.

Germination biology of four climatically varied populations of the invasive species African lovegrass (Eragrostis curvula)

- Roberts, Jason, Florentine, Singarayer, Van Etten, Eddie, Turville, Christopher

Authors: Roberts, Jason , Florentine, Singarayer , Van Etten, Eddie , Turville, Christopher
Date: 2021
Type: Text , Journal article
Relation: Weed Science Vol. 69, no. 2 (2021), p. 210-218
Full Text: false
Reviewed:
Description: African lovegrass [Eragrostis curvula (Schrad.) Nees] is a highly invasive C4 perennial grass that threatens global biodiversity. Appropriate management of this species has been hampered by a lack of knowledge concerning its seed ecology, resulting in significant economic and environmental impacts within various environments. Consequently, this study explored the effects of a selection of environmental factors (photoperiod, alternating temperature, pH, and salinity) by analyzing several measures of germination on four geographically distinct populations of E. curvula to assist in its extirpation from infested sites. Seeds were collected in Australia from Maffra and Shepparton, VIC; Tenterfield, NSW; and Midvale, WA. Key results showed that seeds from Maffra (54% vs. 79%), Tenterfield (38% vs. 61%), and Shepparton (34% vs. 71%) had significantly reduced germination in complete darkness compared with an alternating 12-h light and 12-h dark photoperiod, whereas Midvale had consistent germination (91% vs. 99%). Temperatures between 17/7 C reduced germination for Maffra (42% vs. 73%), Tenterfield (34% vs. 55%), and Shepparton (33% vs. 59%) compared with the mean of all other temperature combinations, whereas Midvale had consistent germination. Furthermore, germination for all populations was consistent between pH 4 and 9. For salinity, germination was significantly reduced at ≥100 mM for Maffra (29% vs. 67%), ≥150 mM for Tenterfield (29% vs. 94%) and Shepparton (39.5% vs. 81.5%), and 250 mM for Midvale (39% vs. 82%) compared with the mean of all other concentrations. Although each trial was conducted independently, the data can be used to generate species-targeted management. Such strategies include maintaining high levels of quarantine and hygiene programs to avoid future spread; where practical, applying light-limiting strategies (mulching, tilling, or scraping) for the Maffra, Tenterfield, and Shepparton populations; and maintaining management efforts year-round, as the species can germinate under a wide range of conditions. © The Author(s), 2021. Published by Cambridge University Press on behalf of the Weed Science Society of America.

Germination biology of three populations of Navua sedge (Cyperus aromaticus)

- Chadha, Aakansha, Florentine, Singarayer, Dhileepan, Kunjithapatham, Dowling, Kim, Turville, Christopher

Authors: Chadha, Aakansha , Florentine, Singarayer , Dhileepan, Kunjithapatham , Dowling, Kim , Turville, Christopher
Date: 2021
Type: Text , Journal article
Relation: Weed Science Vol. 69, no. 1 (2021), p. 69-81
Full Text: false
Reviewed:
Description: Navua sedge [Cyperus aromaticus (Ridley) Mattf. & Kük.] is an aggressive perennial sedge native to equatorial Africa that has become problematic in many Pacific islands and wet, tropical Queensland, Australia. It has had a significant impact on the livestock-grazing industry, sugarcane (Saccharum officinarum L.) and banana (Musa acuminata Colla) plantations, and various other ecosystems. A laboratory-based research investigation was conducted to understand germination and emergence requirements under various environmental conditions of three geographically varied populations sourced from South Johnstone (SJ), Mackay (M) and Nyleta Creek (NC) in Queensland. Germination was identified to be stimulated by light, with no germination recorded under darkness. Populations SJ and NC had optimal germination at alternating temperatures of 25/15, 30/20, and 35/25 C, whereas population M had optimal germination at 25/15 and 30/20 C. All populations recorded greater than 85% germination at all pH levels tested. Seeds of population SJ were more sensitive to salinity compared with populations M and NC, with SJ showing no germination at 100 mM, whereas populations M and NC had 23% and 9% germination, respectively. An inverse relationship was observed between osmotic potential and germination, with no germination recorded at osmotic potentials below -0.8 MPa in any population, indicating moisture availability is a critical requirement for germination. Exposing seeds to 120 C radiant heat completely inhibited germination in populations M and NC, whereas 3% of population SJ germinated following a 180-s exposure at 120 C. Seedling emergence decreased as planting depth increased. Emergence was greatest for seeds on the soil surface or at 0.5-cm burial depth, consistent with germination being stimulated by light. Knowledge of these biological characteristics of C. aromaticus seed germination will assist in investigation of suitable control actions for this species, particularly in the early stage of its invasion into new areas, and will contribute to significant reduction in the soil seedbank. © 2021 Cambridge University Press. All rights reserved.

Quick View

Griefers versus the Griefed - what motivates them to play Massively Multiplayer Online Role-Playing Games?

- Achterbosch, Leigh, Miller, Charlynn, Turville, Christopher, Vamplew, Peter

Authors: Achterbosch, Leigh , Miller, Charlynn , Turville, Christopher , Vamplew, Peter
Date: 2014
Type: Text , Journal article
Relation: The Computer Games Journal Vol. 3, no. 1 (2014), p. 5-18
Full Text:
Reviewed:
Description: 'Griefing' is a term used to describe when a player within a multiplayer online environment intentionally disrupts another player’s game experience for his or her own personal enjoyment or gain. Every day a certain percentage of users of Massively Multiplayer Online Role-Playing Games (MMORPG) are experiencing some form of griefing. There have been studies conducted in the past that attempted to ascertain the factors that motivate users to play MMORPGs. A limited number of studies specifically examined the motivations of users who perform griefing (who are also known as 'griefers'). However, those studies did not examine the motivations of users subjected to griefing. Therefore, the aim of this paper is to examine the factors that motivate the subjects of griefing to play MMORPGs, as well as the factors motivating the griefers. The authors conducted an online survey with the intention to discover the motivations for playing MMORPGs among those whom identified themselves as (i) those that perform griefing, and (ii) those who have been subjected to griefing. A previously devised motivational model by Nick Yee that incorporated ten factors was used to determine the respondents’ motivational trends. In general, players who identified themselves as griefers were more likely to be motivated by all three 'achievement' sub-factors (advancement, game mechanics and competition) at the detriment of all other factors. The subjects of griefing were highly motivated by 'advancement' and 'mechanics', but they ranked 'competition' significantly lower (compared to the griefers). In addition, 'immersion' factors were rated highly by the respondents who were subjected to griefing, with a significantly higher rating of the 'escapism' factor (compared with rankings by griefers). In comparison to the griefers, the respondents subjected to griefing with many years’ experience in the genre of MMORPGs, also placed a greater emphasis on the 'socializing' and 'relationship' factors. Overall, the griefers in this survey considered 'achievement' to be a prime motivating factor, whereas the griefed players tended to be motivated by all ten factors to a similar degree.

Influence of elements of climate change on the growth and fecundity of Datura stramonium

- Chadha, Aakansha, Florentine, Singarayer, Javaid, Muhammad, Welgama, Amali, Turville, Christopher

Authors: Chadha, Aakansha , Florentine, Singarayer , Javaid, Muhammad , Welgama, Amali , Turville, Christopher
Date: 2020
Type: Text , Journal article
Relation: Environmental Science and Pollution Research Vol. 27, no. 28 (2020), p. 35859-35869
Full Text: false
Reviewed:
Description: In this study, the performance of Datura stramonium, an invasive weed of soybean and solanaceous crops, was examined under different elements of climate change. Experiments conducted in CO2 chambers at ambient CO2 (400 ppm) and elevated CO2 (700 ppm) levels under both well-watered and drought conditions exhibited the fertilization effect of elevated CO2. This was, however, limited by drought. Clearly, growth of D. stramonium will be significantly enhanced by enriched atmospheric CO2 concentration under well-watered conditions, producing taller plants with greater biomass and higher seed output. Glasshouse experiments were conducted to evaluate the effect of different soil moisture regimes (100%, 75%, 50% and 25% water-holding capacity (WHC)) on the growth and fecundity of D. stramonium. Plants grown in 75% WHC had the highest plant height (15.24 cm) and shoot diameter (4.25 mm). The lowest leaf area (305.91 mm2), fresh weight (14.48 g) and dry weight (4.45 g) were observed in 25% WHC conditions. The ability of D. stramonium plants to grow and complete their life cycle with high seed output, even under limited water availability, shows the weedy nature of this species which is well adapted to survive future inhospitable climatic conditions. Radiant heat treatment on the plants indicated that temperatures of 120 °C and above for more than 180 s were enough to kill the plants, suggesting that thermal weeding or wildfires will be adequate to act as a circuit breaker on the D. stramonium invasion cycle, thus allowing other control measures to be engaged for greater control. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.

Quick View

North Indian ocean tropical cyclone activity in CMIP5 experiments : future projections using a model-independent detection and tracking scheme

- Bell, Samuel, Chand, Savin, Tory, Kevin, Ye, Hua, Turville, Christopher

Authors: Bell, Samuel , Chand, Savin , Tory, Kevin , Ye, Hua , Turville, Christopher
Date: 2020
Type: Text , Journal article
Relation: International Journal of Climatology Vol. 40, no. 15 (2020), p. 6492-6505
Full Text:
Reviewed:
Description: The sensitivity of tropical cyclone (TC) projection results to different models and the detection and tracking scheme used is well established. In this study, future climate projections of TC activity in the North Indian Ocean (NIO) are assessed with a model- and basin-independent detection and tracking scheme. The scheme is applied to selected models from the coupled model intercomparison project phase 5 (CMIP5) experiments forced under the historical and representative concentration pathway 8.5 (RCP8.5) conditions. Most models underestimated the frequency of early season (April–June) TCs and contained genesis biases equatorward of ~7.5°N in comparison to the historical records. TC tracks detected in reanalysis and model data were input to a clustering algorithm simultaneously, with two clusters in the Arabian Sea and two in the Bay of Bengal (k = 4). Projection results indicated a slight decrease of overall TC genesis frequency in the NIO, with an increase of TC genesis frequency in the Arabian Sea (30–64%) and a decrease in the Bay of Bengal (22–43%), consistent between clusters in each of these sub-regions. These changes were largely due to changes in the pre-monsoon season (April–June) where Bay of Bengal TCs significantly decreased, consistent with changes in vertical ascent. Northern Arabian Sea TCs significantly increased during the pre-monsoon season, consistent with changes in vertical wind shear and relative humidity. There was a projected increase of TC frequency in the post-monsoon season (October–December), consistent with changes in relative humidity and vertical ascent, although not all clusters followed this trend; noting a different response in the southern Bay of Bengal. In turn, these projections caused changes to the climate averaged TC track density, including a decrease (up to 2 TCs per decade) affecting the eastern coast of India and a small increase (up to 0.5 TCs per decade) affecting eastern Africa, Oman and Yemen. © 2020 Royal Meteorological Society

Quick View

Polyclonal T-Cells Express CD1a in Langerhans Cell Histiocytosis (LCH) Lesions

- West, Jennifer, Olsen, Sharon, Mitchell, Jenée, Priddle, Ross, Luke, Jennifer, Åkefeldt, Selma Olsson, Henter, Jan-Inge, Turville, Christopher, Kannourakis, George

Authors: West, Jennifer , Olsen, Sharon , Mitchell, Jenée , Priddle, Ross , Luke, Jennifer , Åkefeldt, Selma Olsson , Henter, Jan-Inge , Turville, Christopher , Kannourakis, George
Date: 2014
Type: Text , Journal article
Relation: PLoS ONE Vol. 9, no. 10 (2014), p. 1-12
Full Text:
Reviewed:
Description: Langerhans cell histiocytosis (LCH) is a complex and poorly understood disorder that has characteristics of both inflammatory and neoplastic disease. By using eight-colour flow cytometry, we have identified a previously unreported population of CD1a+/CD3+ T-cells in LCH lesions. The expression of CD1a is regarded as a hallmark of this disease; however, it has always been presumed that it was only expressed by pathogenic Langerhans cells (LCs). We have now detected CD1a expression by a range of T-cell subsets within all of the LCH lesions that were examined, establishing that CD1a expression in these lesions is no longer restricted to pathogenic LCs. The presence of CD1a+ T-cells in all of the LCH lesions that we have studied to date warrants further investigation into their biological function to determine whether these cells are important in the pathogenesis of LCH. [ABSTRACT FROM AUTHOR] Copyright of PLoS ONE is the property of Public Library of Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Showing items 1 - 20 of 32