Evidence for extreme floods in arid subtropical northwest Australia during the Little Ice Age chronozone (CE 1400-1850)
- Authors: Rouillard, Alexandra , Skrzypek, Grzegorz , Turney, Chris , Dogramaci, Shawan , Hua, Quan , Zawadzki, Atun , Reeves, Jessica , Greenwood, Paul , O'Donnell, Alison , Grierson, Pauline
- Date: 2016
- Type: Text , Journal article
- Relation: Quaternary Science Reviews Vol. 144, no. (2016), p. 107-122
- Full Text: false
- Reviewed:
- Description: Here we report a ~2000-year sediment sequence from the Fortescue Marsh (Martuyitha) in the eastern Pilbara region, which we have used to investigate changing hydroclimatic conditions in the arid subtropics of northwest Australia. The Pilbara is located at the intersection of the tropical Indian and Pacific Oceans and its modern rainfall regime is strongly influenced by tropical cyclones, the Intertropical Convergence Zone (ITCZ) and the Indo-Pacific Warm Pool. We identified four distinct periods within the record. The most recent period (P1: CE ~1990-present) reveals hydroclimatic conditions over recent decades that are the most persistently wet of potentially the last ~2000 years. During the previous centuries (P2: ~CE 1600-1990), the Fortescue Marsh was overall drier but likely punctuated by a number of extreme floods, which are defined here as extraordinary, strongly episodic floods in drylands generated by rainfall events of high volume and intensity. The occurrence of extreme floods during this period, which encompasses the Little Ice Age (LIA; CE 1400-1850), is coherent with other southern tropical datasets along the ITCZ over the last 2000 years, suggesting synchronous hydroclimatic changes across the region. This extreme flood period was preceded by several hundred years (P3: ~CE 700-1600) of less vigorous but more regular flows. The earliest period of the sediment record (P4: ~CE 100-700) was the most arid, with sedimentary and preservation processes driven by prolonged drought. Our results highlight the importance of developing paleoclimate records from the tropical and sub-tropical arid zone, providing a long-term baseline of hydrological conditions in areas with limited historical observations. © 2016 Elsevier Ltd.
Nonsmooth DC programming approach to the minimum sum-of-squares clustering problems
- Authors: Bagirov, Adil , Taheri, Sona , Ugon, Julien
- Date: 2016
- Type: Text , Journal article
- Relation: Pattern Recognition Vol. 53, no. (2016), p. 12-24
- Relation: http://purl.org/au-research/grants/arc/DP140103213
- Full Text: false
- Reviewed:
- Description: This paper introduces an algorithm for solving the minimum sum-of-squares clustering problems using their difference of convex representations. A non-smooth non-convex optimization formulation of the clustering problem is used to design the algorithm. Characterizations of critical points, stationary points in the sense of generalized gradients and inf-stationary points of the clustering problem are given. The proposed algorithm is tested and compared with other clustering algorithms using large real world data sets. © 2015 Elsevier Ltd. All rights reserved.
The epistemic basis of distance running injury research : A historical perspective
- Authors: Hulme, Adam , Finch, Caroline
- Date: 2016
- Type: Text , Journal article , Editorial
- Relation: Journal of Sport and Health Science Vol. 5, no. 2 (2016), p. 172-175
- Relation: http://purl.org/au-research/grants/nhmrc/1058737
- Full Text:
- Reviewed:
Effects of prescribed fire and post-fire rainfall on mercury mobilization and subsequent contamination assessment in a legacy mine site in Victoria, Australia
- Authors: Abraham, Joji , Dowling, Kim , Florentine, Singarayer
- Date: 2018
- Type: Text , Journal article
- Relation: Chemosphere Vol. 190, no. (2018), p. 144-153
- Full Text: false
- Reviewed:
- Description: Prescribed fire conducted in fire-prone areas is a cost-effective choice for forest management, but it also affects many of the physicochemical and bio-geological properties of the forest soil, in a similar manner to wild fires. The aim of this study is to investigate the nature of the mercury mobilization after a prescribed fire and the subsequent temporal changes in concentration. A prescribed fire was conducted in a legacy mine site in Central Victoria, Australia, in late August 2015 and soil sample collection and analyses were carried out two days before and two days after the fire, followed by collection at the end of each season and after an intense rainfall event in September 2016. Results revealed the occurrence of mercury volatilization (8.3–97%) during the fire, and the mercury concentration displayed a significant difference (p < 0.05) before and immediately after the fire. Integrated assessment with number of pollution indices has shown that the study site is extremely contaminated with mercury during all the sampling events, and this poses a serious ecological risk due to the health impacts of mercury on human and ecosystems. In times of climate fluctuation with concomitant increase in forest fire (including prescribed fire), and subsequent precipitation and runoff, the potential for an increased amount of mercury being mobilized is of heighted significance. Therefore, it is recommended that prescribed fire should be cautiously considered as a forest management strategy in any mercury affected landscapes. © 2017 Elsevier Ltd
Jarosite quantification in soils : An enhanced sequential extraction procedure
- Authors: Vithana, Chamindra , Sullivan, Leigh , Bush, Richard , Burton, Edward
- Date: 2014
- Type: Text , Journal article
- Relation: Applied Geochemistry Vol. 51, no. (2014), p. 130-138
- Full Text: false
- Reviewed:
- Description: A two-step sequential extraction procedure established for the quantification of acidity producing ferric and ferrous sulfate minerals such as melanterite and jarosite in acid mine wastes was evaluated for quantification of jarosite spiked in soils. The procedure involves in sequence anoxic water extraction, roasting the solid residue after anoxic water extraction at 550. °C for 1. h, and 4. M HCl extraction of the roasted solid. Soil and quartz samples were spiked with known amounts of synthetic and natural jarosite and their recovery was measured using the suggested two-step sequential extraction procedure. The recoveries of synthetic and natural jarosite were calculated on the basis of the S contents of the initially spiked jarosite in soil and quartz samples. Less than 50% of the spiked jarosite was recovered. The missing S is partially attributable to the retention of jarosite by the Teflon filter membrane used during the filtration of the anoxic water extract. Further investigations also demonstrated a lower 4. M HCl-S extractability from jarosite samples roasted at 550. °C than those roasted at 450. °C. S recovery from jarosite-spiked quartz samples increased to 45-70% by replacing the Teflon filter membrane with the Cellulose Acetate filter membrane and including this filter paper in the second step roasting. This modified method is a step forward in the development of methods to accurately and reliably quantify jarosite in soil materials. © 2014 Elsevier Ltd.
A simple and inexpensive chromium-reducible sulfur method for acid-sulfate soils
- Authors: Burton, Edward , Sullivan, Leigh , Bush, Richard , Johnston, Scott , Keene, Annabelle
- Date: 2008
- Type: Text , Journal article
- Relation: Applied Geochemistry Vol. 23, no. 9 (2008), p. 2759-2766
- Full Text: false
- Reviewed:
- Description: A new chromium-reducible sulfur (CRS) method suitable for the quantification of reduced inorganic S (RIS) in acid-sulfate soils is presented. The new method utilises the reduction of RIS by an acidic Cr(II) solution within a sealed reaction chamber and diffusion of the produced H2S(g) into an alkaline Zn solution. It offers rapid sample processing times, without the need for large volumes of high-purity N2(g) or for specialized, expensive glassware. Examination of pyrite-talc mixtures containing up to 11.8% pyrite, revealed that the method achieves 95-98% recovery of RIS. A comparison between CRS measured by the new diffusion-based method and that measured by a standard purge-and-trap method for 25 pyritic soil samples shows a very strong (r2 = 0.996) linear relationship with a slope of 0.995. The ability of the new diffusion-based CRS method to achieve accurate and precise quantification of RIS in acid-sulfate soils is demonstrated. © 2008 Elsevier Ltd. All rights reserved.
Screening of the ‘Open Scaffolds’ collection from Compounds Australia identifies a new chemical entity with anthelmintic activities against different developmental stages of the barber's pole worm and other parasitic nematodes
- Authors: Preston, Sarah , Jiao, Yaqing , Baell, Jonathan , Keiser, Jennifer , Crawford, Simon , Koehler, Anson , Wang, Tao , Simpson, Moana , Kaplan, Ray , Cowley, Karla , Simpson, Kaylene , Hofmann, Andreas , Jabbar, Abdul , Gasser, Robin
- Date: 2017
- Type: Text , Journal article
- Relation: International Journal for Parasitology: Drugs and Drug Resistance Vol. 7, no. 3 (2017), p. 286-294
- Full Text:
- Reviewed:
- Description: The discovery and development of novel anthelmintic classes is essential to sustain the control of socioeconomically important parasitic worms of humans and animals. With the aim of offering novel, lead-like scaffolds for drug discovery, Compounds Australia released the ‘Open Scaffolds’ collection containing 33,999 compounds, with extensive information available on the physicochemical properties of these chemicals. In the present study, we screened 14,464 prioritised compounds from the ‘Open Scaffolds’ collection against the exsheathed third-stage larvae (xL3s) of Haemonchus contortus using recently developed whole-organism screening assays. We identified a hit compound, called SN00797439, which was shown to reproducibly reduce xL3 motility by ≥ 70%; this compound induced a characteristic, “coiled” xL3 phenotype (IC50 = 3.46–5.93 μM), inhibited motility of fourth-stage larvae (L4s; IC50 = 0.31–12.5 μM) and caused considerable cuticular damage to L4s in vitro. When tested on other parasitic nematodes in vitro, SN00797439 was shown to inhibit (IC50 = 3–50 μM) adults of Ancylostoma ceylanicum (hookworm) and first-stage larvae of Trichuris muris (whipworm) and eventually kill (>90%) these stages. Furthermore, this compound completely inhibited the motility of female and male adults of Brugia malayi (50–100 μM) as well as microfilariae of both B. malayi and Dirofilaria immitis (heartworm). Overall, these results show that SN00797439 acts against genetically (evolutionarily) distant parasitic nematodes i.e. H. contortus and A. ceylanicum [strongyloids] vs. B. malayi and D. immitis [filarioids] vs. T. muris [enoplid], and, thus, might offer a novel, lead-like scaffold for the development of a relatively broad-spectrum anthelmintic. Our future work will focus on assessing the activity of SN00797439 against other pathogens that cause neglected tropical diseases, optimising analogs with improved biological activities and characterising their targets. © 2017 The Authors
Self static interference mitigation scheme for coexisting wireless networks
- Authors: Yaqub, Muhammad , Haider, Ammar , Gondal, Iqbal , Kamruzzaman, Joarder
- Date: 2014
- Type: Text , Journal article
- Relation: Computers and Electrical Engineering Vol. 40, no. 2 (2014), p. 307-318
- Full Text: false
- Reviewed:
- Description: High density of coexisting networks in the Industrial, Scientific and Medical (ISM) band leads to static and self interferences among different communication entities. The inevitability of these interferences demands for interference avoidance schemes to ensure reliability of network operations. This paper proposes a novel Diversified Adaptive Frequency Rolling (DAFR) technique for frequency hopping in Bluetooth piconets. DAFR employs intelligent hopping procedures in order to mitigate self interferences, weeds out the static interferer efficiently and ensures sufficient frequency diversity. We compare the performance of our proposed technique with the widely used existing frequency hopping techniques, namely, Adaptive Frequency Hopping (AFH) and Adaptive Frequency Rolling (AFR). Simulation studies validate the significant improvement in goodput and hopping diversity of our scheme compared to other schemes and demonstrate its potential benefit in real world deployment.
About [q]-regularity properties of collections of sets
- Authors: Kruger, Alexander , Thao, Nguyen
- Date: 2014
- Type: Text , Journal article
- Relation: Journal of Mathematical Analysis and Applications Vol. 416, no. 2 (2014), p. 471-496
- Relation: http://purl.org/au-research/grants/arc/DP110102011
- Full Text:
- Reviewed:
- Description: We examine three primal space local Holder type regularity properties of finite collections of sets, namely, [q]-semiregularity, [q]-subregularity, and uniform [q]-regularity as well as their quantitative characterizations. Equivalent metric characterizations of the three mentioned regularity properties as well as a sufficient condition of [q]-subregularity in terms of Frechet normals are established. The relationships between [q]-regularity properties of collections of sets and the corresponding regularity properties of set-valued mappings are discussed.
- Description: We examine three primal space local Holder type regularity properties of finite collections of sets, namely, [q]-semiregularity, [q]-subregularity, and uniform [q]-regularity as well as their quantitative characterizations. Equivalent metric characterizations of the three mentioned regularity properties as well as a sufficient condition of [q]-subregularity in terms of Frechet normals are established. The relationships between [q]-regularity properties of collections of sets and the corresponding regularity properties of set-valued mappings are discussed. (C) 2014 Elsevier Inc. All rights reserved.
Data analytics identify glycated haemoglobin co-markers for type 2 diabetes mellitus diagnosis
- Authors: Jelinek, Herbert , Stranieri, Andrew , Yatsko, Andrew , Venkatraman, Sitalakshmi
- Date: 2016
- Type: Text , Journal article
- Relation: Computers in Biology and Medicine Vol. 75, no. (2016), p. 90-97
- Full Text: false
- Reviewed:
- Description: Glycated haemoglobin (HbA1c) is being more commonly used as an alternative test for the identification of type 2 diabetes mellitus (T2DM) or to add to fasting blood glucose level and oral glucose tolerance test results, because it is easily obtained using point-of-care technology and represents long-term blood sugar levels. HbA1c cut-off values of 6.5% or above have been recommended for clinical use based on the presence of diabetic comorbidities from population studies. However, outcomes of large trials with a HbA1c of 6.5% as a cut-off have been inconsistent for a diagnosis of T2DM. This suggests that a HbA1c cut-off of 6.5% as a single marker may not be sensitive enough or be too simple and miss individuals at risk or with already overt, undiagnosed diabetes. In this study, data mining algorithms have been applied on a large clinical dataset to identify an optimal cut-off value for HbA1c and to identify whether additional biomarkers can be used together with HbA1c to enhance diagnostic accuracy of T2DM. T2DM classification accuracy increased if 8-hydroxy-2-deoxyguanosine (8-OhdG), an oxidative stress marker, was included in the algorithm from 78.71% for HbA1c at 6.5% to 86.64%. A similar result was obtained when interleukin-6 (IL-6) was included (accuracy=85.63%) but with a lower optimal HbA1c range between 5.73 and 6.22%. The application of data analytics to medical records from the Diabetes Screening programme demonstrates that data analytics, combined with large clinical datasets can be used to identify clinically appropriate cut-off values and identify novel biomarkers that when included improve the accuracy of T2DM diagnosis even when HbA1c levels are below or equal to the current cut-off of 6.5%. © 2016 Elsevier Ltd.
Iron(III) accumulations in inland saline waterways, Hunter Valley, Australia : Mineralogy, micromorphology and pore-water geochemistry
- Authors: Isaacson, Lloyd , Burton, Edward , Bush, Richard , Mitchell, David , Johnston, Scott , Macdonald, Bennett , Sullivan, Leigh , White, Ian
- Date: 2009
- Type: Text , Journal article
- Relation: Applied Geochemistry Vol. 24, no. 10 (2009), p. 1825-1834
- Full Text: false
- Reviewed:
- Description: Discharge of Fe(II)-rich groundwaters into surface-waters results in the accumulation of Fe(III)-minerals in salinized sand-bed waterways of the Hunter Valley, Australia. The objective of this study was to characterise the mineralogy, micromorphology and pore-water geochemistry of these Fe(III) accumulations. Pore-waters had a circumneutral pH (6.2-7.2), were sub-oxic to oxic (Eh 59-453 mV), and had dissolved Fe(II) concentrations up to 81.6 mg L-1. X-ray diffraction (XRD) on natural and acid-ammonium-oxalate (AAO) extracted samples indicated a dominance of 2-line ferrihydrite in most samples, with lesser amounts of goethite, lepidocrocite, quartz, and alumino-silicate clays. The majority of Fe in the samples was bound in the AAO extractable fraction (FeOx) relative to the Na-dithionite extractable fraction (FeDi), with generally high FeOx:FeDi ratios (0.52-0.92). The presence of nano-crystalline 2-line ferrihydrite (Fe5HO3·4H2O) with lesser amounts of goethite (α-FeOOH) was confirmed by scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED). In addition, it was found that lepidocrocite (γ-FeOOH), which occurred as nanoparticles as little as ∼5 lattice spacings thick perpendicular to the (0 2 0) lattice plane, was also present in the studied Fe(III) deposits. Overall, the results highlight the complex variability in the crystallinity and particle-size of Fe(III)-minerals which form via oxidation of Fe(II)-rich groundwaters in sand-bed streams. This variability may be attributed to: (1) divergent precipitation conditions influencing the Fe(II) oxidation rate and the associated supply and hydrolysis of the Fe(III) ion, (2) the effect of interfering compounds, and (3) the influence of bacteria, especially Leptothrix ochracea. © 2009 Elsevier Ltd. All rights reserved.
An investigation of the generation of Acoustic Emission from the flow of particulate solids in pipelines
- Authors: Hii, N. , Tan, Chee Keong , Wilcox, Steven , Chong, Zyh
- Date: 2013
- Type: Text , Journal article
- Relation: Powder Technology Vol. 243, no. (2013), p. 120-129
- Full Text: false
- Reviewed:
- Description: This paper is concerned with the generation of the Acoustic Emission (AE) from particulate flow and an investigation of the potential of implementing AE for flow parameters, namely the solid mass flow rate, particle velocity and size, monitoring. A series of experiments has been conducted to gather AE signals from a laboratory scale single flow-loop pneumatic conveying system. Initially, AE sensors were attached to two steel meshes which were placed with a fixed axial distance in the pipeline to study the generation of the AE and subsequently the possibility of using those generated AE to determine particle velocity in the pipeline. Particle velocities measured from this approach were compared with theoretical predictions. The results indicated that this approach could measure the mean particle velocity with reasonable accuracy. The generation of AE on five different sensor mounting locations was also studied. The results showed that sensors mounted on all those locations were able to respond to changes in the flow parameters. However, only two sensor locations (outer bend and Mesh) were chosen for further investigation. The final experimental results indicated that the AE features, namely Root-Mean-Square (RMS) and energy of the AE, are related to the changes in the flow parameters and good correlations were found. Good correlations between the RMS and energy of the AE with the momentum and kinetic energy of the particles, respectively, were also found. Overall, the studies indicated that features of AE have great potential in gas-solid two phase flow parameter monitoring. However, the studies also show that the applicability of the AE techniques to measure solid mass flow rates in practice would require tedious calibration. © 2013 Elsevier B.V.
Scientific evidence is just the starting point : A generalizable process for developing sports injury prevention interventions
- Authors: Donaldson, Alex , Lloyd, David , Gabbe, Belinda , Cook, Jill , Young, Warren , White, Peta , Finch, Caroline
- Date: 2016
- Type: Text , Journal article
- Relation: Journal of Sport and Health Science Vol. 5, no. 3 (2016), p. 334-341
- Relation: http://purl.org/au-research/grants/nhmrc/1058737
- Relation: http://purl.org/au-research/grants/nhmrc/565907
- Full Text:
- Reviewed:
- Description: Background: The 2 most cited sports injury prevention research frameworks incorporate intervention development, yet little guidance is available in the sports science literature on how to undertake this complex process. This paper presents a generalizable process for developing implementable sports injury prevention interventions, including a case study applying the process to develop a lower limb injury prevention exercise training program (FootyFirst) for community Australian football. Methods: The intervention development process is underpinned by 2 complementary premises: (1) that evidence-based practice integrates the best available scientific evidence with practitioner expertise and end user values and (2) that research evidence alone is insufficient to develop implementable interventions. Results: The generalizable 6-step intervention development process involves (1) compiling research evidence, clinical experience, and knowledge of the implementation context; (2) consulting with experts; (3) engaging with end users; (4) testing the intervention; (5) using theory; and (6) obtaining feedback from early implementers. Following each step, intervention content and presentation should be revised to ensure that the final intervention includes evidence-informed content that is likely to be adopted, properly implemented, and sustained over time by the targeted intervention deliverers. For FootyFirst, this process involved establishing a multidisciplinary intervention development group, conducting 2 targeted literature reviews, undertaking an online expert consensus process, conducting focus groups with program end users, testing the program multiple times in different contexts, and obtaining feedback from early implementers of the program. Conclusion: This systematic yet pragmatic and iterative intervention development process is potentially applicable to any injury prevention topic across all sports settings and levels. It will guide researchers wishing to undertake intervention development.
- Description: Background: The 2 most cited sports injury prevention research frameworks incorporate intervention development, yet little guidance is available in the sports science literature on how to undertake this complex process. This paper presents a generalizable process for developing implementable sports injury prevention interventions, including a case study applying the process to develop a lower limb injury prevention exercise training program (FootyFirst) for community Australian football. Methods: The intervention development process is underpinned by 2 complementary premises: (1) that evidence-based practice integrates the best available scientific evidence with practitioner expertise and end user values and (2) that research evidence alone is insufficient to develop implementable interventions. Results: The generalizable 6-step intervention development process involves (1) compiling research evidence, clinical experience, and knowledge of the implementation context; (2) consulting with experts; (3) engaging with end users; (4) testing the intervention; (5) using theory; and (6) obtaining feedback from early implementers. Following each step, intervention content and presentation should be revised to ensure that the final intervention includes evidence-informed content that is likely to be adopted, properly implemented, and sustained over time by the targeted intervention deliverers. For FootyFirst, this process involved establishing a multidisciplinary intervention development group, conducting 2 targeted literature reviews, undertaking an online expert consensus process, conducting focus groups with program end users, testing the program multiple times in different contexts, and obtaining feedback from early implementers of the program. Conclusion: This systematic yet pragmatic and iterative intervention development process is potentially applicable to any injury prevention topic across all sports settings and levels. It will guide researchers wishing to undertake intervention development. (C) 2016 Production and hosting by Elsevier B.V. on behalf of Shanghai University of Sport.
Schwertmannite transformation to goethite via the Fe(II) pathway : Reaction rates and implications for iron-sulfide formation
- Authors: Burton, Edward , Bush, Richard , Sullivan, Leigh , Mitchell, David
- Date: 2008
- Type: Text , Journal article
- Relation: Geochimica et Cosmochimica Acta Vol. 72, no. 18 (2008), p. 4551-4564
- Full Text: false
- Reviewed:
- Description: Schwertmannite (Fe8O8(OH)6SO4) is a common Fe(III)-oxyhydroxysulfate mineral in acid-sulfate systems, where its formation and fate strongly influence water quality. The present study examines transformation of schwertmannite to goethite (FeOOH), as catalyzed by interactions with Fe(II) in anoxic aquatic environments. This study also evaluates the role of the Fe(II) pathway in influencing the formation of iron-sulfide minerals in such environments. At pH > 5, the rates of Fe(II)-catalyzed schwertmannite transformation were several orders of magnitude faster than transformation in the absence of Fe(II). Complete transformation of schwertmannite occurred within only 3-5 h at pH > 6 and Fe(II)(aq) ≥ 5 mmol L-1. Model calculations indicate that the Fe(II)-catalyzed transformation of schwertmannite to goethite greatly decreases the reactivity of the Fe(III) pool, thereby favoring SO4-reduction and facilitating the formation of iron-sulfide minerals (particularly mackinawite, tetragonal FeS). Examination of in situ sediment geochemistry in an acid-sulfate system revealed that the rapid Fe(II)-catalyzed transformation was consistent with an abrupt shift from an acidic Fe(III)-reducing regime with abundant schwertmannite near the sediment surface, to a near-neutral mackinawite-forming regime where goethite was dominant. This study demonstrates that the Fe(II) pathway exerts a major influence on schwertmannite transformation and iron-sulfide formation in anoxic acid-sulfate systems. These findings have important implications for understanding acidity dynamics and trace element mobility in such systems. © 2008 Elsevier Ltd. All rights reserved.
Differential evolution algorithm for predicting blast induced ground vibrations
- Authors: Saadat, Mahdi , Hasanzade, Ali , Khandelwal, Manoj
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Rock Mechanics and Mining Sciences Vol. 77, no. (2015), p. 97-104
- Full Text:
- Reviewed:
- Description: 1. Introduction One of the most crucial problems in construction blasting is to predict and then mitigate the ground vibration [1]. Blast-induced ground vibration is considered as one of the most important environmental hazards of mining operations and civil engineering projects. Intense vibration can cause critical damage to structures and plants nearby the open-pit mines, dams, and mine slopes, etc [2] and [3]. Researchers who deals with this undesirable phenomenon take into account various range of parameters in order to mitigate the detrimental effects of blasting. Blast influencing parameters can be divided into two categories [2]: (a) Uncontrollable parameters, such as geological and geotechnical characteristics of the rockmass. (b) Controllable parameters, such as burden, spacing, stemming, sub-drilling, delay time, etc.
A strain energy criterion based on grain dislodgment at borehole wall in poorly cemented sands
- Authors: Hashemi, Sam , Melkoumian, Nouné
- Date: 2016
- Type: Text , Journal article
- Relation: International Journal of Rock Mechanics and Mining Sciences Vol. 87, no. (2016), p. 90-103
- Full Text: false
- Reviewed:
- Description: The breakage of bonding between sand particles at a borehole wall usually precedes the borehole failure and it can be considered as a sign that the onset of the borehole collapse is imminent in granular formations. Detecting the particle detachment point and introducing an appropriate failure criterion will play a key role in borehole stability analysis. To investigate the influence of different factors on the initiation of particle debonding at the borehole wall, a series of new laboratory tests was designed and performed on synthetic poorly cemented sand specimens. The tests were devised to allow visual observation of the onset of dislodgment of particles from the borehole wall under various stress paths, for two different borehole sizes and various cement contents. In order to simulate the conducted laboratory tests on TWHC a series of numerical modelling has been conducted by discrete element method to estimate the stresses and strains at the borehole wall. The total strain energy up to the point of the observed particle debonding was calculated for each stress path and a failure criterion based on the total strain energy was introduced. The results showed that the particle detachment point at the borehole wall was reached both before and after the peak strength of the TWHC specimens depending on the stress path and cement content. Also, it was concluded that the stress path has a significant effect on the onset of the particle detachment. The introduced criterion based on absorbed strain energy will help to design more effective support systems for boreholes. © 2016 Elsevier Ltd.
VFR travel : Do visits improve or reduce our quality of life?
- Authors: Backer, Elisa
- Date: 2019
- Type: Text , Journal article
- Relation: Journal of Hospitality and Tourism Management Vol. 38, no. (2019), p. 161-167
- Full Text: false
- Reviewed:
- Description: Quality of Life (QOL) has started to emerge as an important component across numerous disciplines including tourism. Whilst studies regarding QOL have been around for decades in many disciplines, the field is relatively new in tourism. The relationship between QOL and tourism is important given that there have been studies revealing that travel can increase an individual's perceived and actual QOL. Those studies that have examined the relationship between QOL and tourism have focused on pleasure/leisure travel. Thus, other types of travel, namely Visiting Friends and Relatives (VFR) travel have not been examined with respect to QOL. In terms of QOL, VFR can be derided in conversation, identifying it as an unwanted irritation that can hardly boost QOL. This is particularly relevant in terms of VFR hosting. However, the link between VFR and QOL has not been empirically tested and as such, it is unclear whether VFR can improve or reduce QOL. Accordingly, this paper examines the link between VFR travel and QOL. Based on a sample size of 552 across Australia, this research found that whilst VFR can reduce QOL in some situations, in most cases, positive QOL benefits arise from both hosting and visiting VFRs. © 2019
Feasibility and acceptability of a volunteer-mediated diversional therapy program for older patients with cognitive impairment
- Authors: Shee, Anna Wong , Phillips, Bev , Hill, Keith , Dodd, Karen
- Date: 2014
- Type: Text , Journal article
- Relation: Geriatric Nursing Vol. 35, no. 4 (2014), p. 300-305
- Full Text: false
- Reviewed:
- Description: Understanding the perceptions of stakeholders is critical for determining acceptability and feasibility of volunteer-mediated programs. This study evaluated the feasibility and acceptability for staff, volunteers, patients and their carers, of a volunteer diversional therapy program for patients with cognitive impairment undergoing inpatient rehabilitation. Post-program structured interviews were conducted with the volunteers (n = 10), patients (n = 30) and their carers (n = 3); and nursing staff (n = 6) participated in a focus group. Thematic analysis identified five themes (values, attitudes, knowledge, purpose, support) in two dimensions (personal, team culture). Overall, patients, carers, staff and volunteers were satisfied with the volunteer program and perceived benefits for quality of care. Recommendations for improvements to the program related to staff engagement with the program and the volunteers' education and training. The volunteer diversional therapy pilot program for patients with cognitive impairment on a sub-acute ward was acceptable and feasible for patients, carers, staff and volunteers. (C) 2014 Mosby, Inc. All rights reserved.
Does financial system activity affect tax revenue in Malaysia? Bounds testing and causality approach
- Authors: Taha, Roshaiza , Colombage, Sisira , Maslyuk, Svetlana , Nanthakumar, Loganathan
- Date: 2013
- Type: Text , Journal article
- Relation: Journal of Asian Economics Vol. 24, no. (2013), p. 147-157
- Full Text: false
- Reviewed:
- Description: Highlights► We examine the nexus between the financial system and tax revenue collection in Malaysia. ► We found that unidirectional causality running from stock market to direct tax revenue. ► The impact of the financial system on direct tax revenue is more profound in the short run than in the long run. ► Banking and non-banking financial activities play a vital role in determining direct tax revenue. ► Tax incentives contributed more towards increased revenue collection from stock market than corporate debt market. We provide new empirical evidence on the relationship among direct tax revenue and banking and non-banking activities in Malaysia's financial system, utilising monthly data for the period 1997–2008. The existence of the long run equilibrium relationship between tax revenue and the financial system was investigated using the autoregressive distributive lag (ARDL) bounds testing approach to cointegration. We find a long-run equilibrium relationship between the financial system and tax revenue in Malaysia. The short-run dynamic relationship between direct tax revenue and financial system was investigated using the vector error correction model (VECM). The estimated ECTt−1 coefficient indicates a relatively fast speed of adjustment from short-run disequilibrium to long-run equilibrium. The Granger causality tests reveal unidirectional causality running from stock market towards direct tax revenue, indicating that an increase in stock market activities is likely to improve the collection of direct tax revenue. Overall, we show that the impact of the financial system on direct tax revenue is more profound in the short run than in the long run.
Abundance and fractionation of Al, Fe and trace metals following tidal inundation of a tropical acid sulfate soil
- Authors: Johnston, Scott , Burton, Edward , Bush, Richard , Keene, Annabelle , Sullivan, Leigh , Smith, Douglas , McElnea, Angus , Ahern, Col , Powell, Bernard
- Date: 2010
- Type: Text , Journal article
- Relation: Applied Geochemistry Vol. 25, no. 3 (2010), p. 323-335
- Full Text: false
- Reviewed:
- Description: Tidal inundation was restored to a severely degraded tropical acid sulfate soil landscape and subsequent changes in the abundance and fractionation of Al, Fe and selected trace metals were investigated. After 5 a of regular tidal inundation there were large decreases in water-soluble and exchangeable Al fractions within former sulfuric horizons. This was strongly associated with decreased soil acidity and increases in pH, suggesting pH-dependent immobilisation of Al via precipitation as poorly soluble phases. The water-soluble fractions of Fe, Zn, Ni and Mn also decreased. However, there was substantial enrichment (2-5×) of the reactive Fe fraction (FeR; 1 M HCl extractable) near the soil surface, plus a closely corresponding enrichment of 1 M HCl extractable Cr, Zn, Ni and Mn. Surficial accumulations of Fe(III) minerals in the inter-tidal zone were poorly crystalline (up to 38% FeR) and comprised mainly of schwertmannite (Fe8O8(OH)6SO4) with minor quantities of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH). These Fe (III) mineral accumulations provide an effective substrate for the adsorption/co-precipitation and accumulation of trace metals. Arsenic displayed contrary behaviour to trace metals with peak concentrations (∼60 μg g-1) near the redox minima. Changes in the abundance and fractionation of the various metals can be primarily explained by the shift in the geochemical regime from oxic-acidic to reducing-circumneutral conditions, combined with the enrichment of reactive Fe near the soil surface. Whilst increasing sequestration of trace metals via sulfidisation is likely to occur over the long-term, the current abundance of reactive Fe near the sediment-water interface favours a dynamic environment with respect to metals in the tidally inundated areas. © 2009 Elsevier Ltd. All rights reserved.