119 research outputs found
Science and scientific associations in Eastern Australia, 1820-1890
This investigation is concerned with the establishment of science
and scientific associations in the four eastern colonies of Australia,
commencing with the Philosophical Society of Australasia (1821) and
ending with the movement surrounding the formation of the Australasian
Association for the Advancement of Science and other intercolonial
organisations for science in the 1880's.
With the death of Banks in 1820 there ended the first era of
scientific investigation in Australia. In the 1820's the first efforts
to institutionalise science were guided by Sir Thomas Brisbane and his
scientific circle. These first experiments are considered against the
background of reforming science in Britain, whose institutions were to
profoundly affect the course and pattern of science in Australia.
Science in Australia must be seen as part of the spread of 'western
science' into 'colonial' territories.
The first attempts to establish a local-based science in New South
Wales and Van Diemen's Land were ephemeral, affected very much by colonial
politics, faction, individualism, lack of facilities and by the seeds of
deep-seated and longstanding divisions among the principal proponents of
science with differing aspirations and backgrounds. In Van Diemen's Land
in the 1820's and 30's, actively encouraged by men of science in Europe
eager for data, a scientific circle ~merged in Hobart and Launceston which
was to provide a basis upon which Sir John Franklin could build in the
1840's. Franklin's Tasmanian Society produced Australia's first regular
scientific journal the Tasmanian Journal of Natural Science, capitalising
upon the marked growth in scientific investigation and exploration in the
Antipodes at this period and achieving for the first time in the Australian
colonies a forum for the exchange and dissemination of scientific knowledge.
It pointed the way to active intercolonial co-operation in science.
JhNew South Wales after 1830, during twenty-five years of trial and
error attempts to form viable scientific associations, the cause of science
depended heavily upon the 'individual enterprise' of the colony's men of science who remained divided among themselves even within the Australian
Museum committees. Science was bereft of effective vice-regal patronage
but there persisted a productive commitment to scientific research and
debate. In 1856 Sir William Denison, with successful scientific reforms
in Tasmania to his credit, revitalised institutional science in the parent
colony and the bases were laid in his new associations, institutions and
in the University for more professionalism in science and ultimately ror
the essential close co-operation between men of science in the BanksianMacleay
gentlemen-amateur tradition and the growing semi-professional and
professional groups in colonial science.
During the 1850's, despite Denison's reforms, the lead in colonial
science passed to Victoria whose scientific institutions were speedily
and more or less competently founded on the wealth and expertise generated
and attracted by the discovery of gold and the development of its associated
industries. The initiative remained with Victoria during the 1860's. In
Queensland, one of the first Australian territories successfully examined
and exploited by colonial-based scientific enterprise, a settled scientific
community emerged slowly and its efforts were, in the main, correspondingly
limited to those disciplines best suited to its frontier status viz. geology
and natural history. In both Victoria and Queensland where relatively rapid
urban growth followed separation men of science were much concerned with
utilitarian scientific questions such as water-supply, sewerage and transport.
It is argued that Denison's reforms led New South Wales once more to
assume the leadership in the movement 'towards a federated science' from the
late 1870's. Henceforth co-operation, formal and informal, was strengthened
in many fields including astronomy, geology, meteorology and sanitation and
other specialist disciplines as well as in the more popular naturalists'
societies and movements for exploration in the interior, Antarctica and New
Guinea. By the 1880's and 90's science and its associations in Australia
were firmly set in the matrix of the mood and movements for closer intercolonial,
federal co-operation in Australia.
Throughout science is considered in the context of Australian problems,
in the emergence from convict-dependent to self-governing colonies, where scientific efforts were very much affected by the changing dynamics of
colonial society. Science moved throughout the period from the control
of European-based scientists and vice-regal patrons into the hands of
colonial amateurs and professionals and eventually under the surveillance
of colonial legislatures. Science is also considered, where appropriate,
against the development of scientific knowledge in Europe.
The period ends at the commencement of a third era of colonial
scientific development in the nineties when a new and brilliant generation
of university leaders in science commenced to explore new lines of research
and organisation in Australian science aided by the boom of the base-metal
industries, agricultural research and improved facilities and heralding
the move towards federal-political initiatives in science in the following
century
Ionization of clusters in intense laser pulses through collective electron dynamics
The motion of electrons and ions in medium-sized rare gas clusters (1000
atoms) exposed to intense laser pulses is studied microscopically by means of
classical molecular dynamics using a hierarchical tree code. Pulse parameters
for optimum ionization are found to be wavelength dependent. This resonant
behavior is traced back to a collective electron oscillation inside the charged
cluster. It is shown that this dynamics can be well described by a driven and
damped harmonic oscillator allowing for a clear discrimination against other
energy absorption mechanisms.Comment: 4 pages (4 figures
Radio source calibration for the VSA and other CMB instruments at around 30 GHz
Accurate calibration of data is essential for the current generation of CMB
experiments. Using data from the Very Small Array (VSA), we describe procedures
which will lead to an accuracy of 1 percent or better for experiments such as
the VSA and CBI. Particular attention is paid to the stability of the receiver
systems, the quality of the site and frequent observations of reference
sources. At 30 GHz the careful correction for atmospheric emission and
absorption is shown to be essential for achieving 1 percent precision. The
sources for which a 1 percent relative flux density calibration was achieved
included Cas A, Cyg A, Tau A and NGC7027 and the planets Venus, Jupiter and
Saturn. A flux density, or brightness temperature in the case of the planets,
was derived at 33 GHz relative to Jupiter which was adopted as the fundamental
calibrator. A spectral index at ~30 GHz is given for each. Cas A,Tau A, NGC7027
and Venus were examined for variability. Cas A was found to be decreasing at
percent per year over the period March 2001 to August 2004.
In the same period Tau A was decreasing at percent per year. A
survey of the published data showed that the planetary nebula NGC7027 decreased
at percent per year over the period 1967 to 2003. Venus showed
an insignificant ( percent) variation with Venusian illumination.
The integrated polarization of Tau A at 33 GHz was found to be
percent at pa .}Comment: 13 pages, 15 figures, submitted to MNRA
Somatic mutations and clonal dynamics in healthy and cirrhotic human liver.
The most common causes of chronic liver disease are excess alcohol intake, viral hepatitis and non-alcoholic fatty liver disease, with the clinical spectrum ranging in severity from hepatic inflammation to cirrhosis, liver failure or hepatocellular carcinoma (HCC). The genome of HCC exhibits diverse mutational signatures, resulting in recurrent mutations across more than 30 cancer genes1-7. Stem cells from normal livers have a low mutational burden and limited diversity of signatures8, which suggests that the complexity of HCC arises during the progression to chronic liver disease and subsequent malignant transformation. Here, by sequencing whole genomes of 482 microdissections of 100-500 hepatocytes from 5 normal and 9 cirrhotic livers, we show that cirrhotic liver has a higher mutational burden than normal liver. Although rare in normal hepatocytes, structural variants, including chromothripsis, were prominent in cirrhosis. Driver mutations, such as point mutations and structural variants, affected 1-5% of clones. Clonal expansions of millimetres in diameter occurred in cirrhosis, with clones sequestered by the bands of fibrosis that surround regenerative nodules. Some mutational signatures were universal and equally active in both non-malignant hepatocytes and HCCs; some were substantially more active in HCCs than chronic liver disease; and others-arising from exogenous exposures-were present in a subset of patients. The activity of exogenous signatures between adjacent cirrhotic nodules varied by up to tenfold within each patient, as a result of clone-specific and microenvironmental forces. Synchronous HCCs exhibited the same mutational signatures as background cirrhotic liver, but with higher burden. Somatic mutations chronicle the exposures, toxicity, regeneration and clonal structure of liver tissue as it progresses from health to disease.This work was supported by a Wellcome Trust and Cancer Research UK (CRUK) Grand Challenge Award (C98/A24032). P.J.C. is a Wellcome Trust Senior Clinical Fellow (WT088340MA); S.F.B. was supported by the Swiss National Science Foundation (P2SKP3-171753 and P400PB-180790); M.A.S. is supported by a Rubicon fellowship from NWO (019.153LW.038); the Cambridge Human Research Tissue Bank is supported by the NIHR Cambridge Biomedical Research Centre; and M.H. is supported by a CRUK Clinician Scientist Fellowship (C52489/A19924)
One-loop spectroscopy of semiclassically quantized strings: bosonic sector
We make a further step in the analytically exact quantization of spinning string states in semiclassical approximation, by evaluating the exact one-loop partition function for a class of two-spin string solutions for which quadratic fluctuations form a non-trivial system of coupled modes. This is the case of a folded string in the SU(2) sector, in the limit described by a quantum Landau–Lifshitz model. The same applies to the full bosonic sector of fluctuations over the folded spinning string in AdS5 with an angular momentum J in S5. Fluctuations are governed by a special class of fourth-order differential operators, with coefficients being meromorphic functions on the torus, which we are able to solve exactly
A Complete Axiom System for Propositional Interval Temporal Logic with Infinite Time
Interval Temporal Logic (ITL) is an established temporal formalism for
reasoning about time periods. For over 25 years, it has been applied in a
number of ways and several ITL variants, axiom systems and tools have been
investigated. We solve the longstanding open problem of finding a complete
axiom system for basic quantifier-free propositional ITL (PITL) with infinite
time for analysing nonterminating computational systems. Our completeness proof
uses a reduction to completeness for PITL with finite time and conventional
propositional linear-time temporal logic. Unlike completeness proofs of equally
expressive logics with nonelementary computational complexity, our semantic
approach does not use tableaux, subformula closures or explicit deductions
involving encodings of omega automata and nontrivial techniques for
complementing them. We believe that our result also provides evidence of the
naturalness of interval-based reasoning
Cognition and bimanual performance in children with unilateral cerebral palsy: Protocol for a multicentre, cross-sectional study
© 2018 The Author(s). Background: Motor outcomes of children with unilateral cerebral palsy are clearly documented and well understood, yet few studies describe the cognitive functioning in this population, and the associations between the two is poorly understood. Using two hands together in daily life involves complex motor and cognitive processes. Impairment in either domain may contribute to difficulties with bimanual performance. Research is yet to derive whether, and how, cognition affects a child's ability to use their two hands to perform bimanual tasks. Methods/Design: This study will use a prospective, cross-sectional multi-centre observational design. Children (aged 6-12 years) with unilateral cerebral palsy will be recruited from one of five Australian treatment centres. We will examine associations between cognition, bimanual performance and brain neuropathology (lesion type and severity) in a sample of 131 children. The primary outcomes are: Motor - the Assisting Hand Assessment; Cognitive - Executive Function; and Brain - lesion location on structural MRI. Secondary data collected will include: Motor - Box and Blocks, ABILHAND- Kids, Sword Test; Cognitive - standard neuropsychological measures of intelligence. We will use generalized linear modelling and structural equation modelling techniques to investigate relationships between bimanual performance, executive function and brain lesion location. Discussion: This large multi-centre study will examine how cognition affects bimanual performance in children with unilateral cerebral palsy. First, it is anticipated that distinct relationships between bimanual performance and cognition (executive function) will be identified. Second, it is anticipated that interrelationships between bimanual performance and cognition will be associated with common underlying neuropathology. Findings have the potential to improve the specificity of existing upper limb interventions by providing more targeted treatments and influence the development of novel methods to improve both cognitive and motor outcomes in children with unilateral cerebral palsy
Roadless wilderness area determines forest elephant movements in the Congo Basin
A dramatic expansion of road building is underway in the Congo Basin fuelled by private enterprise, international aid, and government aspirations. Among the great wilderness areas on earth, the Congo Basin is outstanding for its high biodiversity, particularly mobile megafauna including forest elephants (Loxodonta africana cyclotis). The abundance of many mammal species in the Basin increases with distance from roads due to hunting pressure, but the impacts of road proliferation on the movements of individuals are unknown. We investigated the ranging behaviour of forest elephants in relation to roads and roadless wilderness by fitting GPS telemetry collars onto a sample of 28 forest elephants living in six priority conservation areas. We show that the size of roadless wilderness is a strong determinant of home range size in this species. Though our study sites included the largest wilderness areas in central African forests, none of 4 home range metrics we calculated, including core area, tended toward an asymptote with increasing wilderness size, suggesting that uninhibited ranging in forest elephants no longer exists. Furthermore we show that roads outside protected areas which are not protected from hunting are a formidable barrier to movement while roads inside protected areas are not. Only 1 elephant from our sample crossed an unprotected road. During crossings her mean speed increased 14-fold compared to normal movements. Forest elephants are increasingly confined and constrained by roads across the Congo Basin which is reducing effective habitat availability and isolating populations, significantly threatening long term conservation efforts. If the current road development trajectory continues, forest wildernesses and the forest elephants they contain will collapse
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