2,981 research outputs found
Southern Queensland's oyster industry
The Southern Queensland oyster industry flourished from the 1870s to around 1920; it peaked soon after the turn of the century and declined from approximately 1910. The emphasis of this paper is a broad overview of these peak years. The industry was confined mostly to southern Queensland where there occurred wide inter-tidal flats along with a suitable edible oyster species — Saccostrea
(Crassostrea) commercialis. This oyster occurs from central Queensland down to the Victorian and New South Wales border and inappropriately is often called the Sydney rock oyster
Portfolio return autocorrelation and non-synchronous trading in UK equities
Although infrequent trading in equity stocks is more prevalent in the United Kingdom (and other non-United States countries), we find that it is proportionally more important in explaining the degree of serial correlation in stock returns in the US than in the UK, in contrast to much of the existing literature.We show that infrequent trading cannot explain more than a small proportion of the serial correlation observed in monthly UK stock returns and hence, other explanations for return predictability must be sought. Many studies have shown that stock market returns in the UK and other international markets are substantially and significantly serially correlated. The success of an investment strategy that is based on the apparent predictability of returns depends on whether the serial correlation is truly random and period specific or due to time varying risk premia or to market microstructure effects. A frequently noted explanation for this serial correlation is market thinness or, more precisely, the infrequency with which a substantial number of UK stocks are traded. Non-synchronous trading results in a measurement error in the observed data for returns on individual stocks, portfolios and market indices. This measurement error generates serial correlation in the observed returns. Here, we assess the extent to which the observed serial correlation in returns can be explained by equity non-trading behaviour. This will reveal whether there is any residual serial correlation left to be explained by alternative sources. We find that, whilst a proportion of the serial correlation in the returns of portfolios of low value stocks can be explained by non-trading, much of it still remains unexplained.
The state of Florida's estuaries and future needs in estuarine research: Part 2. an academic research agenda (review draft)
As a program supporting academic research that addresses recognized societal needs, the
Florida Sea Grant Program is developing a research theme area on estuaries to provide a uniquely academic product that will augment mission-oriented research undertaken by government and by
the private sector. This report is not a call for proposals. It does not prescribe a specific research
plan. Rather, it is a concept paper designed to focus research on two broad "organizing themes":
(1) the hydrology of Florida's estuaries, and (2) the impact of cyclic environmental variability on
estuarine function. (46pp.
Premature mortality in refractory partial epilepsy: does surgical treatment make a difference?
Background: Epilepsy carries an increased risk of premature death. For some people with intractable focal epilepsy, surgery offers hope for a seizure-free life. The authors aimed to see whether epilepsy surgery influenced mortality in people with intractable epilepsy. Methods: The authors audited survival status in two cohorts (those who had surgery and those who had presurgical assessment but did not have surgery). Results: There were 40 known deaths in the non-surgical group (3365 person years of follow-up) and 19 in the surgical group (3905 person-years of follow-up). Non-operated patients were 2.4 times (95% CI 1.4 to 4.2) as likely to die as those who had surgery. They were 4.5 times (95% CI 1.9 to 10.9) as likely to die a probable epilepsy-related death. In the surgical group, those with ongoing seizures 1 year after surgery were 4.0 (95% CI 1.2 to 13.7) times as likely to die as those who were seizure-free or who had only simple partial seizures. Time-dependent Cox analysis showed that the yearly outcome group did not significantly affect mortality (HR 1.3, 95% CI 0.9 to 1.8). Conclusion: Successful epilepsy surgery was associated with a reduced risk of premature mortality, compared with those with refractory focal epilepsy who did not have surgical treatment. To some extent, the reduced mortality is likely to be conferred by inducing freedom from seizures. It is not certain whether better survival is attributable only to surgery, as treatment decisions were not randomised, and there may be inherent differences between the groups.<br/
On the Early History of Current Algebra
The history of Current Algebra is reviewed up to the appearance of the
Adler-Weisberger sum rule. Particular emphasis is given to the role current
algebra played for the historical struggle in strong interaction physics of
elementary particles between the S-matrix approach based on dispersion
relations and field theory. The question whether there are fundamental
particles or all hadrons are bound or resonant states of one another played an
important role in this struggle and is thus also regarded.Comment: 17 page
Palaeozoic petroleum systems of the Irish Sea
This report synthesises the results of the 21CXRM Palaeozoic project in the Irish Sea to
describe the Palaeozoic petroleum systems of that area.
One hydrocarbon play system dominates the basin system: Namurian organic-rich marine
shales (Bowland Shale Formation) generated oil and gas with a peak during maximum burial
of the system in late Jurassic/early Cretaceous time. These hydrocarbons passed to reservoirs
in the Triassic Ormskirk Sandstone (Sherwood Sandstone Group) by way of structures
generated during the Variscan Orogeny and Cenozoic inversion, resulting in the Morecambe,
Hamilton and other gas and oil fields
The Palaeozoic study of the wider Irish Sea area has assessed the potential for more
widespread petroleum systems situated outside the well-known play, particularly within the
Carboniferous.
Within the Main Graben system of the East Irish Sea Basin, Coal Measures strata were
partially removed following Variscan inversion and early Permian uplift. They are not rich in
coals, and not inferred to be a significant source rock. There is some potential in the
Millstone Grit and Yoredale sequences, as some shales (particularly those associated with
marine bands) are known to have high Total Organic Contents. The source rock potential of
shales within the Carboniferous Limestone sequence is poorly constrained by data. A
Devonian source rock is unproven and considered unlikely.
Potential Namurian source rocks, such as the Yoredale Group, have been largely eroded in
the Peel and North Channel basins, considerably reducing their prospectivity, although
terrestrial sequences of equivalent age in the Solway Basin may offer better potential.
The variable seismic data quality at Carboniferous levels and sparsity of deep well control
have led to challenges in interpretation, particularly of the deeper picks. The interpretation of
the surfaces contains a strong model-driven element, evidenced by the onshore relationships
and areas where seismic picks can be made with the greatest confidence. Based upon the
integration of regional seismic mapping with a limited well, source rock and reservoir
property dataset, the most prospective parts of the region, outside the Ormskirk conventional
gas play, are considered to be:
The thick Westphalian sequences preserved in the Eubonia Tilt-Block in Quadrant
109, outside the main Permian-Mesozoic graben system and unaffected by Cenozoic
inversion. The presence and quality of seals form a major risk as the Cumbrian Coast
Group seal is thin or absent and Carboniferous intraformational seals are required but
untested. Based on the limited dataset available in adjacent basins, reservoir quality is
also a significant risk.
A belt of Variscan inversion structures correlated with structures on the Formby
Platform, and Ribbledale Foldbelt onshore, from which hydrocarbons have leaked
into the overlying, Ormskirk-hosted Hamilton fields. The biggest risk here is whether
reservoirs remain unbreached at the Pre-Permian level, and retain good poroperm
characteristics at depths of about 2500 m.
A more speculative play lies in the extensive carbonate platform in Quadrant 109 and
surrounding the Isle of Man, in reefal facies with enhanced secondary porosity. Here,
source rock presence and migration pathways, reservoir properties and seal quality are
major risks
The role of insulin receptor substrate 2 in hypothalamic and β cell function
Insulin receptor substrate 2 (Irs2) plays complex roles in energy homeostasis. We generated mice lacking Irs2 in β cells and a population of hypothalamic neurons (RIPCreIrs2KO), in all neurons (NesCreIrs2KO), and in proopiomelanocortin neurons (POMCCreIrs2KO) to determine the role of Irs2 in the CNS and β cell. RIPCreIrs2KO mice displayed impaired glucose tolerance and reduced β cell mass. Overt diabetes did not ensue, because β cells escaping Cre-mediated recombination progressively populated islets. RIPCreIrs2KO and NesCreIrs2KO mice displayed hyperphagia, obesity, and increased body length, which suggests altered melanocortin action. POMCCreIrs2KO mice did not display this phenotype. RIPCreIrs2KO and NesCreIrs2KO mice retained leptin sensitivity, which suggests that CNS Irs2 pathways are not required for leptin action. NesCreIrs2KO and POMCCreIrs2KO mice did not display reduced β cell mass, but NesCreIrs2KO mice displayed mild abnormalities of glucose homeostasis. RIPCre neurons did not express POMC or neuropeptide Y. Insulin and a melanocortin agonist depolarized RIPCre neurons, whereas leptin was ineffective. Insulin hyperpolarized and leptin depolarized POMC neurons. Our findings demonstrate a critical role for IRS2 in β cell and hypothalamic function and provide insights into the role of RIPCre neurons, a distinct hypothalamic neuronal population, in growth and energy homeostasis
Universality classes in nonequilibrium lattice systems
This work is designed to overview our present knowledge about universality
classes occurring in nonequilibrium systems defined on regular lattices. In the
first section I summarize the most important critical exponents, relations and
the field theoretical formalism used in the text. In the second section I
briefly address the question of scaling behavior at first order phase
transitions. In section three I review dynamical extensions of basic static
classes, show the effect of mixing dynamics and the percolation behavior. The
main body of this work is given in section four where genuine, dynamical
universality classes specific to nonequilibrium systems are introduced. In
section five I continue overviewing such nonequilibrium classes but in coupled,
multi-component systems. Most of the known nonequilibrium transition classes
are explored in low dimensions between active and absorbing states of
reaction-diffusion type of systems. However by mapping they can be related to
universal behavior of interface growth models, which I overview in section six.
Finally in section seven I summarize families of absorbing state system
classes, mean-field classes and give an outlook for further directions of
research.Comment: Updated comprehensive review, 62 pages (two column), 29 figs
included. Scheduled for publication in Reviews of Modern Physics in April
200
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