5,223 research outputs found
Statistical evidence links exceptional 1995 Atlantic hurricane season to record sea warming
Tropical cyclones rank above earthquakes as the major geophysical cause of loss of life and property (Bryant, 1991; Houghton, 1994). In the United States alone, the damage bill from mainland landfalling hurricanes over the last 50 years averages $2.0 billion per year (Hebert et al., 1996). Years with high numbers of hurricanes provide new insight on the environmental factors influencing interannual variability; hence the interest in the exceptional 1995 Atlantic season which saw 11 hurricanes and a total of 19 tropical storms, double the 50-year average. While most environmental factors in 1995 were favourable for tropical cyclone development, we show that a factor not fully explored before, the sea surface temperature (SST) was the most significant. For the 10 degrees-20 degrees N, 20 degrees-60 degrees W region where 93% of the anomalous 1995 hurricanes developed, similar to 45 year statistical regressions show that SST is the dominating influence, independent of all known other factors, behind the interannual variance in Atlantic hurricance numbers. With this SST experiencing record warm levels in 1995, 0.66 degrees C above the 1946-1995 mean, these regressions indicate that sea warming explains 61+/-34% of the anomalous hurricane activity in 1995 to 95% confidence
Implementation of analytical Hartree-Fock gradients for periodic systems
We describe the implementation of analytical Hartree-Fock gradients for
periodic systems in the code CRYSTAL, emphasizing the technical aspects of this
task. The code is now capable of calculating analytical derivatives with
respect to nuclear coordinates for systems periodic in 0, 1, 2 and 3 dimensions
(i.e. molecules, polymers, slabs and solids). Both closed-shell restricted and
unrestricted Hartree-Fock gradients have been implemented. A comparison with
numerical derivatives shows that the forces are highly accurate.Comment: accepted by Comp. Phys. Com
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Pulsatory andesite lava flow at Bagana Volcano
Using a time series of TerraSAR-X spaceborne radar images we have measured the pulsatory motion of an andesite lava flow over a 14-month period at Bagana volcano, Papua New Guinea. Between October 2010 and December 2011, lava flowed continuously down the western flank of the volcano forming a 3 km-long blocky lava flow with a channel, levees, overflows and branches. We captured four successive pulses of lava advancing down the channel system, the first such behaviour of an andesite flow to be recorded using radar. Each pulse had a volume of the order of 107 m3 emplaced over many weeks. The average extrusion rate estimated from the radar data was 0.92 ± 0.35
m3 s-1 , and varied between 0.3 and 1.8 m3 s-1, with higher rates occurring earlier in each pulse. This, together with observations of sulphur dioxide emissions, explosions and incandescence suggest a variable supply rate of magma through Bagana’s conduit as the most likely source of the pulsatory behaviour
NADPH:cytochrome c (P450) reductase activates tirapazamine (SR4233) to restore hypoxic and oxic cytotoxicity in an aerobic resistant derivative of the A549 lung cancer cell line
Tirapazamine (TPZ, SR4233, WIN 59075) is a bioreductive drug that is activated in regions of low oxygen tension to a cytotoxic radical intermediate. This labile metabolite shows high selective toxicity towards hypoxic cells, such as those found in solid tumours. Under aerobic conditions, redox cycling occurs with subsequent generation of superoxide radicals, which are also cytotoxic. NADPH:cytochrome c (P450) reductase (P450R) is a one-electron reducing enzyme that efficiently activates TPZ. Recently a derivative of the A549 non-small cell lung cancer cell line (A549c50) was generated that showed substantially reduced P450R activity compared to its parental line (Elwell et al (1997) Biochem Pharmacol54: 249–257). Here, it is demonstrated that the A549c50 cells are markedly more resistant to TPZ under both aerobic and hypoxic conditions. In addition, these cells have a dramatically impaired ability to metabolize TPZ to its two-electron reduction product, SR4317, under hypoxic conditions when compared to wild-type cells. P450R activity in the A549c50 cells was reintroduced to similar levels as that seen in the parental A549 cells by transfection of the full-length cDNA for human P450R. These P450R over-expressing cells exhibit restored sensitivity to TPZ under both aerobic and hypoxic conditions, comparable to that found in the original parental A549 cells. Further, the ability of the transfected cells to metabolize TPZ to SR4317 under hypoxic conditions is also shown to be restored. This provides further evidence that P450R can play an important role in the activation, metabolism and toxicity of this lead bioreductive drug. © 2000 Cancer Research Campaig
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Probabilistic physically-based cloud screening of satellite infra-red imagery for operational sea surface temperature retrieval
We propose and demonstrate a fully probabilistic (Bayesian) approach to the detection of cloudy pixels in thermal infrared (TIR) imagery observed from satellite over oceans. Using this approach, we show how to exploit the prior information and the fast forward modelling capability that are typically available in the operational context to obtain improved cloud detection. The probability of clear sky for each pixel is estimated by applying Bayes' theorem, and we describe how to apply Bayes' theorem to this problem in general terms. Joint probability density functions (PDFs) of the observations in the TIR channels are needed; the PDFs for clear conditions are calculable from forward modelling and those for cloudy conditions have been obtained empirically. Using analysis fields from numerical weather prediction as prior information, we apply the approach to imagery representative of imagers on polar-orbiting platforms. In comparison with the established cloud-screening scheme, the new technique decreases both the rate of failure to detect cloud contamination and the false-alarm rate by one quarter. The rate of occurrence of cloud-screening-related errors of >1 K in area-averaged SSTs is reduced by 83%. Copyright © 2005 Royal Meteorological Society
Reducing green tape or rolling back IA in Australia: What are found jurisdictions up to?
EIA has been practiced in Australia and the rest of the world for over 40 years, but despite its successes, EIA may now be facing its biggest challenge since it came into being in 1970 with the US National Environmental Policy Act. As Morgan (2012, 11) notes:
“As governments look to stimulate economic growth and create employment in response to the current financial crisis, many are promoting a major expansion of physical infrastructure, encouraging resource development projects, and generally seeking to speed decision-making about development projects. Both EIA and SEA should be even more important in such circumstances, yet the moves taken in some countries to speed up decision-making may weaken the provisions for environmental protection, including impact assessment.”
In this political and economic environment, EIA is under scrutiny. Proposed changes to the EU directive on EIA released in October 2012 contain ten changes to the Articles of the Directive, with six of these referring to either ‘streamlining’ EIA or introducing specific timeframes for parts of the EIA process (European Commission 2012). This scrutiny has not been restricted to economies in recession, but includes those that have avoided recession because of strong resources sectors.
The same appears to be happening in Australia, and this paper reports on these and other possible ‘efficiency’ changes to EIA in Australia at both national and sub-national levels. We attempt to critically examine the nature of such changes and the risks that may be associated with their implementation. Changes to three of the sub-national EIA processes are reviewed in detail, as well as the proposed changes to the national EIA process.
There is always room for more timely assessments, but a critical examination of the potential consequences of these “reforms” on the conduct of EIAs is needed, including whether these efficiency changes will deliver sound environmental management and sustainability-oriented decision-making
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A comparative study of hummingbirds and chickens provides mechanistic insight on the histidine containing dipeptide role in skeletal muscle metabolism
Histidine containing dipeptides (HCDs) have numerous ergogenic and therapeutic properties, but their primary role in skeletal muscle remains unclear. Potential functions include pH regulation, protection against reactive oxygen/nitrogen species, or Ca2+ regulation. In recognition of the challenge of isolating physiological processes in-vivo, we employed a comparative physiology approach to investigate the primary mechanism of HCD action in skeletal muscle. We selected two avian species (i.e., hummingbirds and chickens), who represented the extremes of the physiological processes in which HCDs are likely to function. Our findings indicate that HCDs are non-essential to the development of highly oxidative and contractile muscle, given their very low content in hummingbird skeletal tissue. In contrast, their abundance in the glycolytic chicken muscle, indicate that they are important in anaerobic bioenergetics as pH regulators. This evidence provides new insights on the HCD role in skeletal muscle, which could inform widespread interventions, from health to elite performance
Size and power properties of some tests in the Birnbaum-Saunders regression model
The Birnbaum-Saunders distribution has been used quite effectively to model
times to failure for materials subject to fatigue and for modeling lifetime
data. In this paper we obtain asymptotic expansions, up to order and
under a sequence of Pitman alternatives, for the nonnull distribution functions
of the likelihood ratio, Wald, score and gradient test statistics in the
Birnbaum-Saunders regression model. The asymptotic distributions of all four
statistics are obtained for testing a subset of regression parameters and for
testing the shape parameter. Monte Carlo simulation is presented in order to
compare the finite-sample performance of these tests. We also present an
empirical application.Comment: Paper submitted for publication, with 13 pages and 1 figur
Are we asking the right questions? Working with the LGBTQ+ community to prioritise healthcare research themes.
BackgroundConversations about research priorities with members of the public are rarely designed specifically to include people who identify as Lesbian, Gay, Bisexual, Transgender and Queer (LGBTQ+) and are not researchers.MethodsGenerally, to address this gap, and specifically, to inform future research for CLS, we carried out a rapid review of published research priority sets covering LGBTQ+ topics, and an online workshop to prioritise identified themes.ResultsRapid review: results. The rapid review identified 18 LGBTQ+ research priority sets. Some focussed on specific populations such as women or men, younger or older people or people living within families. Five addressed transgender and gender non- conforming populations. All of the research priority sets originated from English-speaking, high and middle-income countries (UK, US, Canada, and Australia), and date from 2016 onwards. Prioritization approaches were wide-ranging from personal commentary to expert workshops and surveys. Participants involved in setting priorities mostly included research academics, health practitioners and advocacy organisations, two studies involved LGBTQ+ public in their process. Research priorities identified in this review were then grouped into themes which were prioritised during the workshop. Workshop: results. For the workshop, participants were recruited using local (Cambridge, UK) LGBTQ+ networks and a national advert to a public involvement in research matching website to take part in an online discussion workshop. Those that took part were offered payment for their time in preparing for the workshop and taking part. Participants personal priorities and experiences contributed to a consensus development process and a final ranked list of seven research themes and participants' experiences of healthcare, mental health advocacy, care homes, caring responsibilities, schools and family units added additional context.ConclusionsFrom the workshop the three research themes prioritised were: healthcare services delivery, prevention, and particular challenges / intersectionality of multiple challenges for people identifying as LGBTQ+. Research themes interconnected in many ways and this was demonstrated by the comments from workshop participants. This paper offers insights into why these priorities were important from participants' perspectives and detail about how to run an inclusive and respectful public involvement research exercise. On a practical level these themes will directly inform future research direction for CLS
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