917 research outputs found

    The influence of the spectrum of jet turbulence on the stability, NOx emissions and heat release profile of pulverised coal flames.

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    The hypothesis investigated in the current study is that, increasing the scale of, and energy contained in, the larger scales of jet turbulence can beneficially influence the stability of pulverised fuel (PF) flames, their heat release profiles, and NO[subscript]x emissions. The hypothesis is investigated using precessing jet nozzles to enlarge the largest scales of turbulence and shift the energy in the spectrum of turbulence away from the fine scales. These effects are referred to as "enhanced large scale mixing" in the text. Experiments were conducted to measure and compare the effects of a number of types of central jet, located within a co-annular stream, on the turbulent structure of the combined flow. Modelling was performed in water using a planar laser induced fluorescence visualisation technique, and limited to a region corresponding to the pre-ignition region of flames, where reasonable similarity exists. Individual fluid structures were tracked on successive video images. The effects of precession on jet half angles, convection velocities and characteristic strain rates were measured and compared with those of steady jets. In a separate experiment, glass beads with particle size distributions similar to that of pulverised coal, were visualised in non-reacting air jets at ambient temperature, using a planar laser technique. The effects of large-scale structures, generated by centrally located precessing air flows, on particle motion and preferential concentration of particles in an annular jet were measured. Only the region corresponding to the pre-combustion region of flames was investigated since combustion is known to dramatically alter particle motion. The effects of enhanced large scale mixing and particle clustering on PF flames were measured in two refractory lined kilns operated at 130 kW and 2.5 MW, respectively. A scaling parameter, which relates the effects of the dominant mechanisms on flame ignition distance was developed, and used to estimate the influence of enhanced large scale mixing at full scale. The dominant mechanisms, by which enhanced large scale mixing and particle clustering influences combustion, were assessed using sensitivity analyses. It was demonstrated that large-scale particle clustering results from the promotion of the large scales of turbulence. These changes are shown to have potential to provide a means to simultaneously control NO[subscript]x emissions, and improve heat release and stability of PF flames in rotary kiln applications.Thesis (Ph.D.) -- Adelaide University, Dept. of Mechanical Engineering, 200

    An Analysis of Public Attitudes Toward the Insanity Defense

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    Results from a public opinion survey of knowledge, attitudes, and support for the insanity defense indicate that people dislike the insanity defense for both retributive and utilitarian reasons: they want insane law-breakers punished, and they believe that insanity defense procedures fail to protect the public. However, people vastly overestimate the use and success of the insanity plea. Several attitudinal and demographic variables that other researchers have found to be associated with people\u27s support for the death penalty and perceptions of criminal sentencing are also related to support for the insanity defense. Implications for public policy are discussed

    Defining elite athletes: Issues in the study of expert performance in sport psychology

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    © 2014 Elsevier Ltd. Objectives: There has been considerable inconsistency and confusion in the definition of elite/expert athletes in sport psychology research, which has implications for studies conducted in this area and for the field as a whole. This study aimed to: (i) critically evaluate the ways in which recent research in sport psychology has defined elite/expert athletes; (ii) explore the rationale for using such athletes; and (iii) evaluate the conclusions that research in this field draws about the nature of expertise. Design: Conventional systematic review principles were employed to conduct a rigorous search and synthesise findings. Methods: A comprehensive literature search of SPORTDiscus, Academic Search Complete, PsycINFO, and PsycARTICLES was completed in September, 2013 which yielded 91 empirical studies published between 2010 and 2013. The primarily qualitative findings were analysed thematically. Results: Eight ways of defining elite/expert athletes were identified, ranging from Olympic champions to regional level competitors and those with as little as two years of experience in their sport. Three types of rationale were evident in these studies (i.e., "necessity", "exploratory" and "superior"); while findings also indicated that some elite athletes are psychologically idiosyncratic and perhaps even dysfunctional in their behaviour. Finally, only 19 of the 91 included studies provided conclusions about the nature of expertise in sport. Conclusions: This study suggests that the definitions of elite athletes vary on a continuum of validity, and the findings are translated into a taxonomy for classifying expert samples in sport psychology research in future. Recommendations are provided for researchers in this area

    Grounded theory research: literature reviewing and reflexivity

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    <i>Aim</i>: This paper is a report of a discussion of the arguments surrounding the role of the initial literature review in grounded theory. <i>Background</i>: Researchers new to grounded theory may find themselves confused about the literature review, something we ourselves experienced, pointing to the need for clarity about use of the literature in grounded theory to help guide others about to embark on similar research journeys. <i>Discussion</i>: The arguments for and against the use of a substantial topic-related initial literature review in a grounded theory study are discussed, giving examples from our own studies. The use of theoretically sampled literature and the necessity for reflexivity are also discussed. Reflexivity is viewed as the explicit quest to limit researcher effects on the data by awareness of self, something seen as integral both to the process of data collection and the constant comparison method essential to grounded theory. <i>Conclusion</i>: A researcher who is close to the field may already be theoretically sensitized and familiar with the literature on the study topic. Use of literature or any other preknowledge should not prevent a grounded theory arising from the inductive–deductive interplay which is at the heart of this method. Reflexivity is needed to prevent prior knowledge distorting the researcher’s perceptions of the data

    Psychological approaches to understanding and promoting recovery in psychosis and bipolar disorder:a mixed-methods approach

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    BackgroundRecovery in mental health is a relatively new concept, but it is becoming more accepted that people can recover from psychosis. Recovery-orientated services are recommended for adult mental health, but with little evidence base to support this. ObjectivesTo facilitate understanding and promotion of recovery in psychosis and bipolar disorder (BD), in a manner that is empowering and acceptable to service users. MethodThere were six linked projects using qualitative and quantitative methodologies: (1) developing and piloting a service user-defined measure of recovery; (2) a Delphi study to determine levels of consensus around the concept of recovery; (3) examination of the psychological factors associated with recovery and how these fluctuate over time; (4) development and evaluation of cognitive–behavioural approaches to guided self-help including a patient preference trial (PPT); (5) development and evaluation of cognitive–behavioural therapy (CBT) for understanding and preventing suicide in psychosis including a randomised controlled trial (RCT); and (6) development and evaluation of a cognitive–behavioural approach to recovery in recent onset BD, including a RCT of recovery-focused cognitive–behavioural therapy (RfCBT). Service user involvement was central to the programme. ResultsMeasurement of service user-defined recovery from psychosis (using the Subjective Experience of Psychosis Scale) and BD (using the Bipolar Recovery Questionnaire) was shown to be feasible and valid. The consensus study revealed a high level of agreement among service users for defining recovery, factors that help or hinder recovery and items which demonstrate recovery. Negative emotions, self-esteem and hope predicted recovery judgements, both cross-sectionally and longitudinally, whereas positive symptoms had an indirect effect. In the PPT, 89 participants entered the study, three were randomised, 57 were retained in the trial until 15-month follow-up (64%). At follow-up there was no overall treatment effect on the primary outcome (Questionnaire about the Process of Recovery total; p = 0.82). In the suicide prevention RCT, 49 were randomised and 35 were retained at 6-month follow-up (71%). There were significant improvements in suicidal ideation [Adult Suicidal Ideation Questionnaire; treatment effect = –12.3, 95% confidence interval (CI) –24.3 to –0.14], Suicide Probability Scale (SPS; treatment effect = –7.0, 95% CI –15.5 to 0) and hopelessness (subscale of the SPS; treatment effect = –3.8, 95% CI –7.3 to –0.5) at follow-up. In the RCT for BD, 67 participants were randomised and 45 were retained at the 12-month follow-up (67%). Recovery score significantly improved in comparison with treatment as usual (TAU) at follow-up (310.87, 95% CI 75.00 to 546.74). At 15-month follow-up, 32 participants had experienced a relapse of either depression or mania (20 TAU vs. 12 RfCBT). The difference in time to recurrence was significant (estimated hazard ratio 0.38, 95% CI 0.18 to 0.78; p < 0.006). ConclusionsThis research programme has improved our understanding of recovery in psychosis and BD. Key findings indicate that measurement of recovery is feasible and valid. It would be feasible to scale up the RCTs to assess effectiveness of our therapeutic approaches in larger full trials, and two of the studies (CBT for suicide prevention in psychosis and recovery in BD) found significant benefits on their primary outcomes despite limited statistical power, suggesting definitive trials are warranted. FundingThe National Institute for Health Research Programme Grants for Applied Research programme

    Justify your alpha

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    Benjamin et al. proposed changing the conventional “statistical significance” threshold (i.e.,the alpha level) from p ≤ .05 to p ≤ .005 for all novel claims with relatively low prior odds. They provided two arguments for why lowering the significance threshold would “immediately improve the reproducibility of scientific research.” First, a p-value near .05provides weak evidence for the alternative hypothesis. Second, under certain assumptions, an alpha of .05 leads to high false positive report probabilities (FPRP2 ; the probability that a significant finding is a false positive

    Synergies between the key biodiversity area and systematic conservation planning approaches

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    Systematic conservation planning and Key Biodiversity Areas (KBAs) are the two most widely used approaches for identifying important sites for biodiversity. However, there is limited advice for conservation policy makers and practitioners on when and how they should be combined. Here we provide such guidance, using insights from the recently developed Global Standard for the Identification of KBAs and the language of decision science to review and clarify their similarities and differences. We argue the two approaches are broadly similar, with both setting transparent environmental objectives and specifying actions. There is however greater contrast in the data used and actions involved, as the KBA approach uses biodiversity data alone and identifies sites for monitoring and vigilance actions at a minimum, whereas systematic conservation planning combines biodiversity and implementation‐relevant data to guide management actions. This difference means there is much scope for combining approaches, so conservation planners should use KBA data in their analyses, setting context‐specific targets for each KBA type, and planners and donors should use systematic conservation planning techniques when prioritizing between KBAs for management action. In doing so, they will benefit conservation policy, practice and research by building on the collaborations formed through the KBA Standard's development

    Abdominal aortic aneurysm is associated with a variant in low-density lipoprotein receptor-related protein 1

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    Abdominal aortic aneurysm (AAA) is a common cause of morbidity and mortality and has a significant heritability. We carried out a genome-wide association discovery study of 1866 patients with AAA and 5435 controls and replication of promising signals (lead SNP with a p value &lt; 1 × 10-5) in 2871 additional cases and 32,687 controls and performed further follow-up in 1491 AAA and 11,060 controls. In the discovery study, nine loci demonstrated association with AAA (p &lt; 1 × 10-5). In the replication sample, the lead SNP at one of these loci, rs1466535, located within intron 1 of low-density-lipoprotein receptor-related protein 1 (LRP1) demonstrated significant association (p = 0.0042). We confirmed the association of rs1466535 and AAA in our follow-up study (p = 0.035). In a combined analysis (6228 AAA and 49182 controls), rs1466535 had a consistent effect size and direction in all sample sets (combined p = 4.52 × 10-10, odds ratio 1.15 [1.10-1.21]). No associations were seen for either rs1466535 or the 12q13.3 locus in independent association studies of coronary artery disease, blood pressure, diabetes, or hyperlipidaemia, suggesting that this locus is specific to AAA. Gene-expression studies demonstrated a trend toward increased LRP1 expression for the rs1466535 CC genotype in arterial tissues; there was a significant (p = 0.029) 1.19-fold (1.04-1.36) increase in LRP1 expression in CC homozygotes compared to TT homozygotes in aortic adventitia. Functional studies demonstrated that rs1466535 might alter a SREBP-1 binding site and influence enhancer activity at the locus. In conclusion, this study has identified a biologically plausible genetic variant associated specifically with AAA, and we suggest that this variant has a possible functional role in LRP1 expression

    State of the climate in 2018

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    In 2018, the dominant greenhouse gases released into Earth’s atmosphere—carbon dioxide, methane, and nitrous oxide—continued their increase. The annual global average carbon dioxide concentration at Earth’s surface was 407.4 ± 0.1 ppm, the highest in the modern instrumental record and in ice core records dating back 800 000 years. Combined, greenhouse gases and several halogenated gases contribute just over 3 W m−2 to radiative forcing and represent a nearly 43% increase since 1990. Carbon dioxide is responsible for about 65% of this radiative forcing. With a weak La Niña in early 2018 transitioning to a weak El Niño by the year’s end, the global surface (land and ocean) temperature was the fourth highest on record, with only 2015 through 2017 being warmer. Several European countries reported record high annual temperatures. There were also more high, and fewer low, temperature extremes than in nearly all of the 68-year extremes record. Madagascar recorded a record daily temperature of 40.5°C in Morondava in March, while South Korea set its record high of 41.0°C in August in Hongcheon. Nawabshah, Pakistan, recorded its highest temperature of 50.2°C, which may be a new daily world record for April. Globally, the annual lower troposphere temperature was third to seventh highest, depending on the dataset analyzed. The lower stratospheric temperature was approximately fifth lowest. The 2018 Arctic land surface temperature was 1.2°C above the 1981–2010 average, tying for third highest in the 118-year record, following 2016 and 2017. June’s Arctic snow cover extent was almost half of what it was 35 years ago. Across Greenland, however, regional summer temperatures were generally below or near average. Additionally, a satellite survey of 47 glaciers in Greenland indicated a net increase in area for the first time since records began in 1999. Increasing permafrost temperatures were reported at most observation sites in the Arctic, with the overall increase of 0.1°–0.2°C between 2017 and 2018 being comparable to the highest rate of warming ever observed in the region. On 17 March, Arctic sea ice extent marked the second smallest annual maximum in the 38-year record, larger than only 2017. The minimum extent in 2018 was reached on 19 September and again on 23 September, tying 2008 and 2010 for the sixth lowest extent on record. The 23 September date tied 1997 as the latest sea ice minimum date on record. First-year ice now dominates the ice cover, comprising 77% of the March 2018 ice pack compared to 55% during the 1980s. Because thinner, younger ice is more vulnerable to melting out in summer, this shift in sea ice age has contributed to the decreasing trend in minimum ice extent. Regionally, Bering Sea ice extent was at record lows for almost the entire 2017/18 ice season. For the Antarctic continent as a whole, 2018 was warmer than average. On the highest points of the Antarctic Plateau, the automatic weather station Relay (74°S) broke or tied six monthly temperature records throughout the year, with August breaking its record by nearly 8°C. However, cool conditions in the western Bellingshausen Sea and Amundsen Sea sector contributed to a low melt season overall for 2017/18. High SSTs contributed to low summer sea ice extent in the Ross and Weddell Seas in 2018, underpinning the second lowest Antarctic summer minimum sea ice extent on record. Despite conducive conditions for its formation, the ozone hole at its maximum extent in September was near the 2000–18 mean, likely due to an ongoing slow decline in stratospheric chlorine monoxide concentration. Across the oceans, globally averaged SST decreased slightly since the record El Niño year of 2016 but was still far above the climatological mean. On average, SST is increasing at a rate of 0.10° ± 0.01°C decade−1 since 1950. The warming appeared largest in the tropical Indian Ocean and smallest in the North Pacific. The deeper ocean continues to warm year after year. For the seventh consecutive year, global annual mean sea level became the highest in the 26-year record, rising to 81 mm above the 1993 average. As anticipated in a warming climate, the hydrological cycle over the ocean is accelerating: dry regions are becoming drier and wet regions rainier. Closer to the equator, 95 named tropical storms were observed during 2018, well above the 1981–2010 average of 82. Eleven tropical cyclones reached Saffir–Simpson scale Category 5 intensity. North Atlantic Major Hurricane Michael’s landfall intensity of 140 kt was the fourth strongest for any continental U.S. hurricane landfall in the 168-year record. Michael caused more than 30 fatalities and 25billion(U.S.dollars)indamages.InthewesternNorthPacific,SuperTyphoonMangkhutledto160fatalitiesand25 billion (U.S. dollars) in damages. In the western North Pacific, Super Typhoon Mangkhut led to 160 fatalities and 6 billion (U.S. dollars) in damages across the Philippines, Hong Kong, Macau, mainland China, Guam, and the Northern Mariana Islands. Tropical Storm Son-Tinh was responsible for 170 fatalities in Vietnam and Laos. Nearly all the islands of Micronesia experienced at least moderate impacts from various tropical cyclones. Across land, many areas around the globe received copious precipitation, notable at different time scales. Rodrigues and Réunion Island near southern Africa each reported their third wettest year on record. In Hawaii, 1262 mm precipitation at Waipā Gardens (Kauai) on 14–15 April set a new U.S. record for 24-h precipitation. In Brazil, the city of Belo Horizonte received nearly 75 mm of rain in just 20 minutes, nearly half its monthly average. Globally, fire activity during 2018 was the lowest since the start of the record in 1997, with a combined burned area of about 500 million hectares. This reinforced the long-term downward trend in fire emissions driven by changes in land use in frequently burning savannas. However, wildfires burned 3.5 million hectares across the United States, well above the 2000–10 average of 2.7 million hectares. Combined, U.S. wildfire damages for the 2017 and 2018 wildfire seasons exceeded $40 billion (U.S. dollars)
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