Showing papers by "University of New South Wales published in 2009"

IntCal13 and Marine13 radiocarbon age calibration curves 0-50,000 years cal BP

Abstract: Additional co-authors: TJ Heaton, AG Hogg, KA Hughen, KF Kaiser, B Kromer, SW Manning, RW Reimer, DA Richards, JR Southon, S Talamo, CSM Turney, J van der Plicht, CE Weyhenmeyer

Regulation of inflammatory responses by gut microbiota and chemoattractant receptor GPR43

Abstract: The immune system responds to pathogens by a variety of pattern recognition molecules such as the Toll-like receptors (TLRs), which promote recognition of dangerous foreign pathogens. However, recent evidence indicates that normal intestinal microbiota might also positively influence immune responses, and protect against the development of inflammatory diseases. One of these elements may be short-chain fatty acids (SCFAs), which are produced by fermentation of dietary fibre by intestinal microbiota. A feature of human ulcerative colitis and other colitic diseases is a change in 'healthy' microbiota such as Bifidobacterium and Bacteriodes, and a concurrent reduction in SCFAs. Moreover, increased intake of fermentable dietary fibre, or SCFAs, seems to be clinically beneficial in the treatment of colitis. SCFAs bind the G-protein-coupled receptor 43 (GPR43, also known as FFAR2), and here we show that SCFA-GPR43 interactions profoundly affect inflammatory responses. Stimulation of GPR43 by SCFAs was necessary for the normal resolution of certain inflammatory responses, because GPR43-deficient (Gpr43(-/-)) mice showed exacerbated or unresolving inflammation in models of colitis, arthritis and asthma. This seemed to relate to increased production of inflammatory mediators by Gpr43(-/-) immune cells, and increased immune cell recruitment. Germ-free mice, which are devoid of bacteria and express little or no SCFAs, showed a similar dysregulation of certain inflammatory responses. GPR43 binding of SCFAs potentially provides a molecular link between diet, gastrointestinal bacterial metabolism, and immune and inflammatory responses.

IL28B is associated with response to chronic hepatitis C interferon-alpha and ribavirin therapy

Abstract: Hepatitis C virus (HCV) infects 3% of the world's population. Treatment of chronic HCV consists of a combination of PEGylated interferon-alpha (PEG-IFN-alpha) and ribavirin (RBV). To identify genetic variants associated with HCV treatment response, we conducted a genome-wide association study of sustained virological response (SVR) to PEG-IFN-alpha/RBV combination therapy in 293 Australian individuals with genotype 1 chronic hepatitis C, with validation in an independent replication cohort consisting of 555 individuals. We report an association to SVR within the gene region encoding interleukin 28B (IL28B, also called IFNlambda3; rs8099917 combined P = 9.25 x 10(-9), OR = 1.98, 95% CI = 1.57-2.52). IL28B contributes to viral resistance and is known to be upregulated by interferons and by RNA virus infection. These data suggest that host genetics may be useful for the prediction of drug response, and they also support the investigation of the role of IL28B in the treatment of HCV and in other diseases treated with IFN-alpha.

Association of Torture and Other Potentially Traumatic Events With Mental Health Outcomes Among Populations Exposed to Mass Conflict and Displacement: A Systematic Review and Meta-analysis

Abstract: Context Uncertainties continue about the roles that methodological factors and key risk factors, particularly torture and other potentially traumatic events (PTEs), play in the variation of reported prevalence rates of posttraumatic stress disorder (PTSD) and depression across epidemiologic surveys among postconflict populations worldwide. Objective To undertake a systematic review and meta-regression of the prevalence rates of PTSD and depression in the refugee and postconflict mental health field. Data Sources An initial pool of 5904 articles, identified through MEDLINE, PsycINFO and PILOTS, of surveys involving refugee, conflict-affected populations, or both, published in English-language journals between 1980 and May 2009. Study Selection Surveys were limited to those of adult populations (n ≥ 50) reporting PTSD prevalence, depression prevalence, or both. Excluded surveys comprised patients, war veterans, and civilian populations (nonrefugees/asylum seekers) from high-income countries exposed to terrorist attacks or involved in distal conflicts (≥25 years). Data Extraction Methodological factors (response rate, sample size and design, diagnostic method) and substantive factors (sociodemographics, place of survey, torture and other PTEs, Political Terror Scale score, residency status, time since conflict). Data Synthesis A total of 161 articles reporting results of 181 surveys comprising 81 866 refugees and other conflict-affected persons from 40 countries were identified. Rates of reported PTSD and depression showed large intersurvey variability (0%-99% and 3%-85.5%, respectively). The unadjusted weighted prevalence rate reported across all surveys for PTSD was 30.6% (95% CI, 26.3%-35.2%) and for depression was 30.8% (95% CI, 26.3%-35.6%). Methodological factors accounted for 12.9% and 27.7% PTSD and depression, respectively. Nonrandom sampling, small sample sizes, and self-report questionnaires were associated with higher rates of mental disorder. Adjusting for methodological factors, reported torture (Δ total R 2 between base methodological model and base model + substantive factor [ΔR 2 ] = 23.6%; OR, 2.01; 95% CI, 1.52-2.65) emerged as the strongest factor associated with PTSD, followed by cumulative exposure to PTEs (ΔR 2 = 10.8%; OR, 1.52; 95% CI, 1.21-1.91), time since conflict (ΔR 2 = 10%; OR, 0.77; 95% CI, 0.66-0.91), and assessed level of political terror (ΔR 2 = 3.5%; OR, 1.60; 95% CI, 1.03-2.50). For depression, significant factors were number of PTEs (ΔR 2 = 22.0%; OR, 1.64; 95% CI, 1.39-1.93), time since conflict (ΔR 2 = 21.9%; OR, 0.80; 95% CI, 0.69-0.93), reported torture (ΔR 2 = 11.4%; OR, 1.48; 95% CI, 1.07-2.04), and residency status (ΔR 2 = 5.0%; OR, 1.30; 95% CI, 1.07-1.57). Conclusion Methodological factors and substantive population risk factors, such as exposure to torture and other PTEs, after adjusting for methodological factors account for higher rates of reported prevalence of PTSD and depression.

The International GNSS Service in a changing landscape of Global Navigation Satellite Systems

Abstract: The International GNSS Service (IGS) is an international activity involving more than 200 participating organisations in over 80 countries with a track record of one and a half decades of successful operations. The IGS is a service of the International Association of Geodesy (IAG). It primarily supports scientific research based on highly precise and accurate Earth observations using the technologies of Global Navigation Satellite Systems (GNSS), primarily the US Global Positioning System (GPS). The mission of the IGS is “to provide the highest-quality GNSS data and products in support of the terrestrial reference frame, Earth rotation, Earth observation and research, positioning, navigation and timing and other applications that benefit society”. The IGS will continue to support the IAG’s initiative to coordinate cross-technique global geodesy for the next decade, via the development of the Global Geodetic Observing System (GGOS), which focuses on the needs of global geodesy at the mm-level. IGS activities are fundamental to scientific disciplines related to climate, weather, sea level change, and space weather. The IGS also supports many other applications, including precise navigation, machine automation, and surveying and mapping. This article discusses the IGS Strategic Plan and future directions of the globally-coordinated ~400 station IGS network, tracking data and information products, and outlines the scope of a few of its numerous working groups and pilot projects as the world anticipates a truly multi-system GNSS in the coming decade.

Methadone maintenance therapy versus no opioid replacement therapy for opioid dependence

Abstract: BACKGROUND: Methadone maintenance was the first widely used opioid replacement therapy to treat heroin dependence, and it remains the best-researched treatment for this problem. Despite the widespread use of methadone in maintenance treatment for opioid dependence in many countries, it is a controversial treatment whose effectiveness has been disputed. OBJECTIVES: To evaluate the effects of methadone maintenance treatment (MMT) compared with treatments that did not involve opioid replacement therapy (i.e., detoxification, offer of drug-free rehabilitation, placebo medication, wait-list controls) for opioid dependence. SEARCH STRATEGY: We searched the following databases up to Dec 2008: the Cochrane Controlled Trials Register, EMBASE, PubMED, CINAHL, Current Contents, Psychlit, CORK [www. state.vt.su/adap/cork], Alcohol and Drug Council of Australia (ADCA) [www.adca.org.au], Australian Drug Foundation (ADF-VIC) [www.adf.org.au], Centre for Education and Information on Drugs and Alcohol (CEIDA) [www.ceida.net.au], Australian Bibliographic Network (ABN), and Library of Congress databases, available NIDA monographs and the College on Problems of Drug Dependence Inc. proceedings, the reference lists of all identified studies and published reviews; authors of identified RCTs were asked about other published or unpublished relevant RCTs. SELECTION CRITERIA: All randomised controlled clinical trials of methadone maintenance therapy compared with either placebo maintenance or other non-pharmacological therapy for the treatment of opioid dependence. DATA COLLECTION AND ANALYSIS: Reviewers evaluated the papers separately and independently, rating methodological quality of sequence generation, concealment of allocation and bias. Data were extracted independently for meta-analysis and double-entered. MAIN RESULTS: Eleven studies met the criteria for inclusion in this review, all were randomised clinical trials, two were double-blind. There were a total number of 1969 participants. The sequence generation was inadequate in one study, adequate in five studies and unclear in the remaining studies. The allocation of concealment was adequate in three studies and unclear in the remaining studies. Methadone appeared statistically significantly more effective than non-pharmacological approaches in retaining patients in treatment and in the suppression of heroin use as measured by self report and urine/hair analysis (6 RCTs, RR = 0.66 95% CI 0.56-0.78), but not statistically different in criminal activity (3 RCTs, RR=0.39; 95%CI: 0.12-1.25) or mortality (4 RCTs, RR=0.48; 95%CI: 0.10-2.39). AUTHORS' CONCLUSIONS: Methadone is an effective maintenance therapy intervention for the treatment of heroin dependence as it retains patients in treatment and decreases heroin use better than treatments that do not utilise opioid replacement therapy. It does not show a statistically significant superior effect on criminal activity or mortality.

Resting Microglia Directly Monitor the Functional State of Synapses In Vivo and Determine the Fate of Ischemic Terminals

Abstract: Recent studies have identified the important contribution of glial cells to the plasticity of neuronal circuits. Resting microglia, the primary immune effector cells in the brain, dynamically extend and retract their processes as if actively surveying the microenvironment. However, just what is being sampled by these resting microglial processes has not been demonstrated in vivo, and the nature and function of any interactions between microglia and neuronal circuits is incompletely understood. Using in vivo two-photon imaging of fluorescent-labeled neurons and microglia, we demonstrate that the resting microglial processes make brief (∼5 min) and direct contacts with neuronal synapses at a frequency of about once per hour. These contacts are activity-dependent, being reduced in frequency by reductions in neuronal activity. After transient cerebral ischemia, the duration of these microglia–synapse contacts are markedly prolonged (∼1 h) and are frequently followed by the disappearance of the presynaptic bouton. Our results demonstrate that at least part of the dynamic motility of resting microglial processes in vivo is directed toward synapses and propose that microglia vigilantly monitor and respond to the functional status of synapses. Furthermore, the striking finding that some synapses in the ischemic areas disappear after prolonged microglial contact suggests microglia contribute to the subsequent increased turnover of synaptic connections. Further understanding of the mechanisms involved in the microglial detection of the functional state of synapses, and of their role in remodeling neuronal circuits disrupted by ischemia, may lead to novel therapies for treating brain injury that target microglia.

A randomized trial of vertebroplasty for osteoporotic spinal fractures

Abstract: Background Vertebroplasty is commonly used to treat painful, osteoporotic vertebral compression fractures. Methods In this multicenter trial, we randomly assigned 131 patients who had one to three painful osteoporotic vertebral compression fractures to undergo either vertebroplasty or a simulated procedure without cement (control group). The primary outcomes were scores on the modified Roland–Morris Disability Questionnaire (RDQ) (on a scale of 0 to 23, with higher scores indicating greater disability) and patients' ratings of average pain intensity during the preceding 24 hours at 1 month (on a scale of 0 to 10, with higher scores indicating more severe pain). Patients were allowed to cross over to the other study group after 1 month. Results All patients underwent the assigned intervention (68 vertebroplasties and 63 simulated procedures). The baseline characteristics were similar in the two groups. At 1 month, there was no significant difference between the vertebroplasty group and the control group in...

Dexmedetomidine vs midazolam for sedation of critically ill patients: a randomized trial.

Abstract: Context γ-Aminobutyric acid receptor agonist medications are the most commonly used sedatives for intensive care unit (ICU) patients, yet preliminary evidence indicates that the α 2 agonist dexmedetomidine may have distinct advantages Objective To compare the efficacy and safety of prolonged sedation with dexmedetomidine vs midazolam for mechanically ventilated patients Design, Setting, and Patients Prospective, double-blind, randomized trial conducted in 68 centers in 5 countries between March 2005 and August 2007 among 375 medical/surgical ICU patients with expected mechanical ventilation for more than 24 hours Sedation level and delirium were assessed using the Richmond Agitation-Sedation Scale (RASS) and the Confusion Assessment Method for the ICU Interventions Dexmedetomidine (02-14 μg/kg per hour [n = 244]) or midazolam (002-01 mg/kg per hour [n = 122]) titrated to achieve light sedation (RASS scores between −2 and +1) from enrollment until extubation or 30 days Main Outcome Measures Percentage of time within target RASS range Secondary end points included prevalence and duration of delirium, use of fentanyl and open-label midazolam, and nursing assessments Additional outcomes included duration of mechanical ventilation, ICU length of stay, and adverse events Results There was no difference in percentage of time within the target RASS range (773% for dexmedetomidine group vs 751% for midazolam group; difference, 22% [95% confidence interval {CI}, −32% to 75%]; P = 18) The prevalence of delirium during treatment was 54% (n = 132/244) in dexmedetomidine-treated patients vs 766% (n = 93/122) in midazolam-treated patients (difference, 226% [95% CI, 14% to 33%]; P Conclusions There was no difference between dexmedetomidine and midazolam in time at targeted sedation level in mechanically ventilated ICU patients At comparable sedation levels, dexmedetomidine-treated patients spent less time on the ventilator, experienced less delirium, and developed less tachycardia and hypertension The most notable adverse effect of dexmedetomidine was bradycardia Trial Registration clinicaltrialsgov Identifier: NCT00216190Published online February 2, 2009 (doi:101001/jama200956)

Biological determinants of endocrine resistance in breast cancer

Abstract: The efficacy of endocrine therapies (such as tamoxifen) in breast cancer is limited by intrinsic and acquired therapeutic resistance. What do we know about the genetic lesions and molecular processes that determine endocrine resistance in the clinic, and how can we use this to improve therapy? Endocrine therapies targeting oestrogen action (anti-oestrogens, such as tamoxifen, and aromatase inhibitors) decrease mortality from breast cancer, but their efficacy is limited by intrinsic and acquired therapeutic resistance. Candidate molecular biomarkers and gene expression signatures of tamoxifen response emphasize the importance of deregulation of proliferation and survival signalling in endocrine resistance. However, definition of the specific genetic lesions and molecular processes that determine clinical endocrine resistance is incomplete. The development of large-scale computational and genetic approaches offers the promise of identifying the mediators of endocrine resistance that may be exploited as potential therapeutic targets and biomarkers of response in the clinic.

Cooperative Communications for Cognitive Radio Networks

Abstract: Cognitive radio is an exciting emerging technology that has the potential of dealing with the stringent requirement and scarcity of the radio spectrum. Such revolutionary and transforming technology represents a paradigm shift in the design of wireless systems, as it will allow the agile and efficient utilization of the radio spectrum by offering distributed terminals or radio cells the ability of radio sensing, self-adaptation, and dynamic spectrum sharing. Cooperative communications and networking is another new communication technology paradigm that allows distributed terminals in a wireless network to collaborate through some distributed transmission or signal processing so as to realize a new form of space diversity to combat the detrimental effects of fading channels. In this paper, we consider the application of these technologies to spectrum sensing and spectrum sharing. One of the most important challenges for cognitive radio systems is to identify the presence of primary (licensed) users over a wide range of spectrum at a particular time and specific geographic location. We consider the use of cooperative spectrum sensing in cognitive radio systems to enhance the reliability of detecting primary users. We shall describe spectrum sensing for cognitive radios and propose robust cooperative spectrum sensing techniques for a practical framework employing cognitive radios. We also investigate cooperative communications for spectrum sharing in a cognitive wireless relay network. To exploit the maximum spectrum opportunities, we present a cognitive space-time-frequency coding technique that can opportunistically adjust its coding structure by adapting itself to the dynamic spectrum environment.

Acute-on-chronic liver failure: consensus recommendations of the Asian Pacific Association for the study of the liver (APASL)

Abstract: The Asian Pacific Association for the Study of the Liver (APASL) set up a working party on acute-on-chronic liver failure (ACLF) in 2004, with a mandate to develop consensus guidelines on various aspects of ACLF relevant to disease patterns and clinical practice in the Asia-Pacific region. Experts predominantly from the Asia–Pacific region constituted this working party and were requested to identify different issues of ACLF and develop the consensus guidelines. A 2-day meeting of the working party was held on January 22–23, 2008, at New Delhi, India, to discuss and finalize the consensus statements. Only those statements that were unanimously approved by the experts were accepted. These statements were circulated to all the experts and subsequently presented at the Annual Conference of the APASL at Seoul, Korea, in March 2008. The consensus statements along with relevant background information are presented in this review.

Modeling and Simulation of Scalable Cloud Computing Environments and the CloudSim Toolkit: Challenges and Opportunities

Abstract: Cloud computing aims to power the next generation data centers and enables application service providers to lease data center capabilities for deploying applications depending on user QoS (Quality of Service) requirements. Cloud applications have different composition, configuration, and deployment requirements. Quantifying the performance of resource allocation policies and application scheduling algorithms at finer details in Cloud computing environments for different application and service models under varying load, energy performance (power consumption, heat dissipation), and system size is a challenging problem to tackle. To simplify this process, in this paper we propose CloudSim: an extensible simulation toolkit that enables modelling and simulation of Cloud computing environments. The CloudSim toolkit supports modelling and creation of one or more virtual machines (VMs) on a simulated node of a Data Center, jobs, and their mapping to suitable VMs. It also allows simulation of multiple Data Centers to enable a study on federation and associated policies for migration of VMs for reliability and automatic scaling of applications.

Gram-scale production of graphene based on solvothermal synthesis and sonication

Abstract: Carbon nanostructures have emerged as likely candidates for a wide range of applications, driving research into novel synthetic techniques to produce nanotubes, graphene and other carbon-based materials. Single sheets of pristine graphene have been isolated from bulk graphite in small amounts by micromechanical cleavage1, and larger amounts of chemically modified graphene sheets have been produced by a number of approaches2,3,4,5,6,7. Both of these techniques make use of highly oriented pyrolitic graphite as a starting material and involve labour-intensive preparations. Here, we report the direct chemical synthesis of carbon nanosheets in gram-scale quantities in a bottom-up approach based on the common laboratory reagents ethanol and sodium, which are reacted to give an intermediate solid that is then pyrolized, yielding a fused array of graphene sheets that are dispersed by mild sonication. The ability to produce bulk graphene samples from non-graphitic precursors with a scalable, low-cost approach should take us a step closer to real-world applications of graphene. Most techniques for producing graphene use graphite as a starting material and are labour-intensive. The direct chemical synthesis of carbon nanosheets in gram-scale quantities from the common laboratory reagents ethanol and sodium has now been demonstrated. The ability to produce bulk graphene samples from non-graphitic precursors with a scalable, low-cost approach should take us a step closer to real-world applications of graphene.

Family caregivers of people with dementia

Abstract: Family caregivers of people with dementia, often called the invisible second patients, are critical to the quality of life of the care recipients. The effects of being a family caregiver, though sometimes positive, are generally negative, with high rates of burden and psychological morbidity as well as social isolation, physical ill-health, and financial hardship. Caregivers vulnerable to adverse effects can be identified, as can factors which ameliorate or exacerbate burden and strain. Psychosocial interventions have been demonstrated to reduce caregiver burden and depression and delay nursing home admission. Comprehensive management of the patient with dementia includes building a partnership between health professionals and family caregivers, referral to Alzheimer's Associations, and psychosocial interventions where indicated.

The International Committee for Monitoring Assisted Reproductive Technology (ICMART) and the World Health Organization (WHO) Revised Glossary on ART Terminology, 2009

Abstract: Background Many definitions used in medically assisted reproduction (MAR) vary in different settings, making it difficult to standardize and compare procedures in different countries and regions. With the expansion of infertility interventions worldwide, including lower resource settings, the importance and value of a common nomenclature is critical. The objective is to develop an internationally accepted and continually updated set of definitions, which would be utilized to standardize and harmonize international data collection, and to assist in monitoring the availability, efficacy, and safety of assisted reproductive technology (ART) being practiced worldwide. Method Seventy-two clinicians, basic scientists, epidemiologists and social scientists gathered together at the WHO headquarters in Geneva, Switzerland in December, 2008. Several months in advance, three working groups were established which were responsible for terminology in three specific areas: clinical conditions and procedures, laboratory procedures and outcome measures. Each group reviewed the existing ICMART glossary, made recommendations for revisions and introduced new terms to be considered for glossary expansion. Results A consensus was reached on 87 terms, expanding the original glossary by 34 terms, which included definitions for numerous clinical and laboratory procedures. Special emphasis was placed in describing outcome measures such as cumulative delivery rates and other markers of safety and efficacy in ART. Conclusions Standardized terminology should assist in analysis of worldwide trends in MAR interventions and in the comparison of ART outcomes across countries and regions. This glossary will contribute to a more standardized communication among professionals responsible for ART practice, as well as those responsible for national, regional and international registries.

Modeling and simulation of scalable Cloud computing environments and the CloudSim toolkit: Challenges and opportunities

Abstract: Cloud computing aims to power the next generation data centers and enables application service providers to lease data center capabilities for deploying applications depending on user QoS (Quality of Service) requirements. Cloud applications have different composition, configuration, and deployment requirements. Quantifying the performance of resource allocation policies and application scheduling algorithms at finer details in Cloud computing environments for different application and service models under varying load, energy performance (power consumption, heat dissipation), and system size is a challenging problem to tackle. To simplify this process, in this paper we propose CloudSim: an extensible simulation toolkit that enables modelling and simulation of Cloud computing environments. The CloudSim toolkit supports modelling and creation of one or more virtual machines (VMs) on a simulated node of a Data Center, jobs, and their mapping to suitable VMs. It also allows simulation of multiple Data Centers to enable a study on federation and associated policies for migration of VMs for reliability and automatic scaling of applications.

Bioapplications of RAFT polymerization.

Abstract: A living radical polymerization (LRP) is a free radical polymerization that aims at displaying living character, (i.e., does not terminate or transfer and is able to continue polymerization once the initial feed is exhausted by addition of more monomer). However, termination reactions are inherent to a radical process, and modern LRP techniques seek to minimize such reactions, therefore providing control over the molecular weight and the molecular weight distribution of a polymeric material. In addition, the better LRP techniques incorporate many of the desirable features of traditional free radical polymerization, such as compatibility with a wide range of monomers, tolerance of many functionalities, and facile reaction conditions. The control of molecular weight and molecular weight distribution has enabled access to complex architectures and site specific functionality that were previously impossible to achieve via traditional free radical polymerizations. These LRPs are classified in three different subgroups: (1) stable free-radical polymerization such as nitroxide mediated polymerization (NMP),1,2 (2) degenerative transfer polymerization, such as iodine transfer polymerization (ITP and RITP),3,4 single electron transfer-degenerative transfer living radical polymerization(SET-DTLRP),5,6reversibleaddition-fragmentation chain transfer (RAFT),7,8 and macromolecular design via the interchange of xanthates (MADIX)9,10 polymerization, and (3) metal mediated catalyzed polymerization, such as atom transfer radical polymerization (ATRP),11-14 single electron transfer-living radical polymerization (SET-LRP),15 and organotellurium mediated living radical polymrization16-19 Among the existing LRP techniques, RAFT and MADIX are probably the most versatile processes, as they are tolerant * E-mail: T.P.D., T.Davis@UNSW.edu.au; S.P., S.Perrier@ chem.usyd.edu.au. † Centre for Advanced Macromolecular Design (CAMD), School of Chemical Sciences & Engineering, UNSW. ‡ Centre for Advanced Macromolecular Design (CAMD), School of Biotechnology & Biomolecular Sciences, UNSW. § The University of Sydney. Chem. Rev. 2009, 109, 5402–5436 5402

Assurance on sustainability reports: an international comparison

Abstract: Globally, companies increasingly publish separate general purpose, nonfinancial (sustainability) reports. Some of these are independently assured and assurers may or may not be from the auditing profession. We seek to understand this emerging voluntary assurance market. Using a sample of 2,113 companies (from 31 countries) that produced sustainability reports between 2002–2004, we use sequential logit analysis to identify the factors associated with the decision to voluntarily purchase assurance and the choice of assurance provider. We hypothesize that a company's need to enhance credibility through assurance and choice of assurance provider will be a function of company‐, industry‐, and country‐related factors. Our results support the argument that companies seeking to enhance the credibility of their reports and build their corporate reputation are more likely to have their sustainability reports assured, although it does not matter whether the assurance provider comes from the auditing profes...

2007 National Survey of Mental Health and Wellbeing: Methods and key findings.

Abstract: Objective: To provide a description of the methods and key findings of the 2007 Australian National Survey of Mental Health and Wellbeing. Method: A national face-to-face household survey of 8841 (60% response rate) community residents aged between 16 and 85 years was carried out using the World Mental Health Survey Initiative version of the Composite International Diagnostic Interview. Diagnoses were made according to ICD-10. Key findings include the prevalence of mental disorder, sex and age distributions of mental disorders, severity of mental disorders, comorbidity among mental disorders, and the extent of disability and health service use associated with mental disorders. Results: The prevalence of any lifetime mental disorder was 45.5%. The prevalence of any 12 month mental disorder was 20.0%, with anxiety disorders (14.4%) the most common class of mental disorder followed by affective disorders (6.2%) and substance use disorders (5.1%). Mental disorders, particularly affective disorders, were disabling. One in four people (25.4%) with 12 month mental disorders had more than one class of mental disorder. One-third (34.9%) of people with a mental disorder used health services for mental health problems in the 12 months prior to the interview. Conclusions: Mental disorders are common in Australia. Many people have more than one class of mental disorder. Mental disorders are associated with substantial disability, yet many people with mental disorders do not seek help for their mental health problems.

Information theoretic measures for clusterings comparison: is a correction for chance necessary?

Abstract: Information theoretic based measures form a fundamental class of similarity measures for comparing clusterings, beside the class of pair-counting based and set-matching based measures. In this paper, we discuss the necessity of correction for chance for information theoretic based measures for clusterings comparison. We observe that the baseline for such measures, i.e. average value between random partitions of a data set, does not take on a constant value, and tends to have larger variation when the ratio between the number of data points and the number of clusters is small. This effect is similar in some other non-information theoretic based measures such as the well-known Rand Index. Assuming a hypergeometric model of randomness, we derive the analytical formula for the expected mutual information value between a pair of clusterings, and then propose the adjusted version for several popular information theoretic based measures. Some examples are given to demonstrate the need and usefulness of the adjusted measures.

Optimization of cooperative spectrum sensing with energy detection in cognitive radio networks

Abstract: We consider cooperative spectrum sensing in which multiple cognitive radios collaboratively detect the spectrum holes through energy detection and investigate the optimality of cooperative spectrum sensing with an aim to optimize the detection performance in an efficient and implementable way. We derive the optimal voting rule for any detector applied to cooperative spectrum sensing. We also optimize the detection threshold when energy detection is employed. Finally, we propose a fast spectrum sensing algorithm for a large network which requires fewer than the total number of cognitive radios in cooperative spectrum sensing while satisfying a given error bound.

Intralocus sexual conflict.

Abstract: Intralocus sexual conflict occurs when selection on a shared trait in one sex displaces the other sex from its phenotypic optimum. It arises because many shared traits have a common genetic basis but undergo contrasting selection in the sexes. A recent surge of interest in this evolutionary tug of war has yielded evidence of such conflicts in laboratory and natural populations. Here we highlight outstanding questions about the causes and consequences of intralocus sexual conflict at the genomic level, and its long-term implications for sexual coevolution. Whereas recent thinking has focussed on the role of intralocus sexual conflict as a brake on sexual coevolution, we urge a broader appraisal that also takes account of its potential to drive adaptive evolution and speciation.

The propositional nature of human associative learning.

Abstract: The past 50 years have seen an accumulation of evidence suggesting that associative learning depends on high-level cognitive processes that give rise to propositional knowledge. Yet, many learning theorists maintain a belief in a learning mechanism in which links between mental representations are formed automatically. We characterize and highlight the differences between the propositional and link approaches, and review the relevant empirical evidence. We conclude that learning is the consequence of propositional reasoning processes that cooperate with the unconscious processes involved in memory retrieval and perception. We argue that this new conceptual framework allows many of the important recent advances in associative learning research to be retained, but recast in a model that provides a firmer foundation for both immediate application and future research.

The path to 25% silicon solar cell efficiency: History of silicon cell evolution

Abstract: The first silicon solar cell was reported in 1941 and had less than 1% energy conversion efficiency compared to the 25% efficiency milestone reported in this paper. Standardisation of past measurements shows there has been a 57% improvement between confirmed results in 1983 and the present result. The features of the cell structure responsible for the most recent performance increase are described and the history of crystalline and multicrystalline silicon cell efficiency evolution is documented. Copyright © 2009 John Wiley & Sons, Ltd.