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The search for life in the Universe is a fundamental problem of astrobiology and modern science. The current progress in the detection of terrestrial-type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favourable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of global (astrospheric), and local (atmospheric and surface) environments of exoplanets in the habitable zones (HZs) around G-K-M dwarf stars including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favourable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro)physical, chemical and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the HZ to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field in light of presentations and discussions during the NASA Nexus for Exoplanetary System Science funded workshop ‘Exoplanetary Space Weather, Climate and Habitability’ and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology.
Blood samples from normal and Plasmodium berghei infected mice are being analyzed for trace elements by charged particle induced x-rays. Approximately 0.25 ml of the sample (whole blood, washed red cells, or plasma) is dry ashed. The ashes are mounted on a 0.003 inch Kapton foil. The analysis is performed by bombardment of the samples by a beam of 2.0 MeV protons and detection of the characteristic x-rays by a 175-eV-resolution lithium-drifted silicon detector. The data are analyzed by an on-line PDP-9 computer-based data acquisition system. Results indicate an increase in the K, Ca, Cu, and Zn per unit volume of the red cells of the malaria infected mice relative to the amounts measured for uninfected blood, and a decrease in the K, Ca, and Fe and an increase in the Cu per unit volume in the plasma of the infected mice.
Radio survey datasets comprise an increasing number of individual observations stored as sets of multidimensional data. In large survey projects, astronomers commonly face limitations regarding: 1) interactive visual analytics of sufficiently large subsets of data; 2) synchronous and asynchronous collaboration; and 3) documentation of the discovery workflow. To support collaborative data inquiry, we present encube, a large-scale comparative visual analytics framework. encube can utilise advanced visualization environments such as the CAVE2 (a hybrid 2D and 3D virtual reality environment powered with a 100 Tflop/s GPU-based supercomputer and 84 million pixels) for collaborative analysis of large subsets of data from radio surveys. It can also run on standard desktops, providing a capable visual analytics experience across the display ecology. encube is composed of four primary units enabling compute-intensive processing, advanced visualisation, dynamic interaction, parallel data query, along with data management. Its modularity will make it simple to incorporate astronomical analysis packages and Virtual Observatory capabilities developed within our community. We discuss how encube builds a bridge between high-end display systems (such as CAVE2) and the classical desktop, preserving all traces of the work completed on either platform – allowing the research process to continue wherever you are.
A new orbit has been derived for the binary Cepheid S Sagittae = HD 188727 = BD+16°4067, using both extant data and new radial velocities derived from radial velocity spectrometer observations at McDonald Observatory and the Dominion Astrophysical Observatory. We deconvoled both the pulsational and orbital components from the observed velocities in order to fit a truncated Fourier series to the pulsation velocities and to derive orbital elements respectively. We confirm the orbital elements given in Herbig and Moore (1952) and speculate that the secular trend evident in the orbital (O-C) diagram may be interpreted as evidence for a third component. (See Evans, Slovak and Welch, this volume, for IUE observations supporting this interpretation.)
We have applied an approximately Bayesian and a fully Bayesian analysis to the calculation of Cepheid distances, radii and absolute magnitudes using the surface brightness (Baade–Wesselink) method. Both methods successfully account for errors in the data, provide unbiased distance estimates, and provide objective model selection for the radial velocity curve. In addition, the fully Bayesian analysis objectively selects a model for the magnitude curve; averages over models of various Fourier orders, properly weighted by the posterior probabilities of the individual models; and includes a Lutz–Kelker correction.
The approximately Bayesian method is that described by Jefferys & Barnes (1999) and Barnes & Jefferys (1999). It is a maximum likelihood approach with objective selection of the order of the Fourier series model of the radial velocities.
The Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey aims to characterise the physical and chemical evolution of high-mass star-forming clumps. Exploiting the unique broad frequency range and on-the-fly mapping capabilities of the Australia Telescope National Facility Mopra 22 m single-dish telescope1, MALT90 has obtained 3′ × 3′ maps towards ~2 000 dense molecular clumps identified in the ATLASGAL 870 μm Galactic plane survey. The clumps were selected to host the early stages of high-mass star formation and to span the complete range in their evolutionary states (from prestellar, to protostellar, and on to
regions and photodissociation regions). Because MALT90 mapped 16 lines simultaneously with excellent spatial (38 arcsec) and spectral (0.11 km s−1) resolution, the data reveal a wealth of information about the clumps’ morphologies, chemistry, and kinematics. In this paper we outline the survey strategy, observing mode, data reduction procedure, and highlight some early science results. All MALT90 raw and processed data products are available to the community. With its unprecedented large sample of clumps, MALT90 is the largest survey of its type ever conducted and an excellent resource for identifying interesting candidates for high-resolution studies with ALMA.
Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.
Tomography is a standard and invaluable technique that covers a large range of length scales. It gives access to the inner morphology of specimens and to the three-dimensional (3D) distribution of physical quantities such as elemental composition, crystalline phases, oxidation state, or strain. These data are necessary to determine the effective properties of investigated heterogeneous media. However, each tomographic technique relies on severe sampling conditions and physical principles that require the sample to be adequately shaped. For that purpose, a wide range of sample preparation techniques is used, including mechanical machining, polishing, sawing, ion milling, or chemical techniques. Here, we focus on the basics of tomography that justify such advanced sample preparation, before reviewing and illustrating the main techniques. Performances and limits are highlighted, and we identify the best preparation technique for a particular tomographic scale and application. The targeted tomography techniques include hard X-ray micro- and nanotomography, electron nanotomography, and atom probe tomography. The article mainly focuses on hard condensed matter, including porous materials, alloys, and microelectronics applications, but also includes, to a lesser extent, biological considerations.
We present a framework to volume-render three-dimensional data cubes interactively using distributed ray-casting and volume-bricking over a cluster of workstations powered by one or more graphics processing units (GPUs) and a multi-core central processing unit (CPU). The main design target for this framework is to provide an in-core visualization solution able to provide three-dimensional interactive views of terabyte-sized data cubes. We tested the presented framework using a computing cluster comprising 64 nodes with a total of 128 GPUs. The framework proved to be scalable to render a 204 GB data cube with an average of 30 frames per second. Our performance analyses also compare the use of NVIDIA Tesla 1060 and 2050 GPU architectures and the effect of increasing the visualization output resolution on the rendering performance. Although our initial focus, as shown in the examples presented in this work, is volume rendering of spectral data cubes from radio astronomy, we contend that our approach has applicability to other disciplines where close to real-time volume rendering of terabyte-order three-dimensional data sets is a requirement.
General-purpose computing on graphics processing units (GPGPU) is dramatically changing the landscape of high performance computing in astronomy. In this paper, we identify and investigate several key decision areas, with a goal of simplifying the early adoption of GPGPU in astronomy. We consider the merits of OpenCL as an open standard in order to reduce risks associated with coding in a native, vendor-specific programming environment, and present a GPU programming philosophy based on using brute force solutions. We assert that effective use of new GPU-based supercomputing facilities will require a change in approach from astronomers. This will likely include improved programming training, an increased need for software development best practice through the use of profiling and related optimisation tools, and a greater reliance on third-party code libraries. As with any new technology, those willing to take the risks and make the investment of time and effort to become early adopters of GPGPU in astronomy, stand to reap great benefits.
Efficient 1.54 μm emission under 1064nm excitation of Er3+/Yb3+ codoped silica fibre is reported. The energy transfer efficiency from Yb3+ to Er3+, of at least 85%, even under high inversion, is comparable to that in multicomponent glass fibres. Fibre design parameters are discussed and results presented. Small signal gain of ˜ 45dB is also measured and a power amplifier giving 145mW output power demonstrated.
In a factory population the occurrence of reactions to tetanus toxoid was recorded after 6740 injections. The incidence of general reactions was 0·3 % and of local reactions 2·6%. The local reaction rate to the first injection of the basic immunization course was 0·9%, to the second injection 2·7%, and to the third injection 7·4%. To booster injections the rate was 1·6%. The local reaction rate was appreciably higher in women than in men – 14·4 % and 5·7 % respectively in the case of the third injection – and the incidence among women increased with age.
Tetanus vaccine containing 10 Lf of toxoid caused fewer reactions than one containing 20 Lf, but a reduction in the content of aluminium adjuvant did not affect the reaction rate.
Almost all reactors were found to have a satisfactory serum antitoxin concentration at the time of the reaction or developed a satisfactory immunity within 1–6 months.
Skin tests were made in 32 hypersensitive patients. Neither the diluent, thiomersal preservative, nor the culture medium appeared to be responsible for hypersensitivity. The degree of hypersensitivity elicited by a special highly purified toxoid was only very slightly less than that elicited by the commercially pure toxoid. It is suggested that reactions are largely due to the toxoid antigen itself rather than to impurities or other components of the vaccine.
A single intranasal dose of 107.0 EID50 recombinant WRL 105 strain live attenuated influenza vaccine was administered intranasally to 193 volunteers either as nose drops or by one of three spray devices which produced sprays of differing physical characteristics. In volunteers with homologous haemagglutinating inhibiting antibody titres of ⋜ 20 before vaccination, seroconversion rates varied widely from 80% following the administration of drops to 71%, 57% and 28% with the three spray devices.
In the week following vaccination 16 (22%) of 74 volunteers who were found to show a fourfold or greater antibody response took analgesics to control symptoms in comparison with 4 (7%) of 58 volunteers who exhibited no sero-logical response to vaccination (P < 0.05). However, neither the occurrence of upper respiratory nor systemic symptoms were significantly different in these two groups and the degree of attenuation of the recombinant WRL 105 strain appears to be acceptable for future use.
Epidemiological investigation into an outbreak of food poisoning in 17 patients caused by Salmonella enteritidis phage-type 4 demonstrated a highly significant association with consumption of custard, retailed in custard slices and trifles from a bakery on one day. The bakery had changed their recipe for custard 2 weeks earlier to include fresh shell eggs and had not followed earlier national advice on cooking eggs for human consumption. The case-control study supports earlier work associating Salmonella enteritidis phage-type 4 infection with consumption of uncooked or lightly cooked shell eggs.
Joe Barnes, Research FellowJames A. Baker III Institute for Public Policy, Rice University,
Mark H. Hayes, Research Fellow, Program on Energy and Sustainable DevelopmentFreeman Spogli Institute for International Studies, Stanford University,
Amy M. Jaffe, Rice University,
David G. Victor, Director, Program on Energy and Sustainable DevelopmentFreeman Spogli Institute for International Studies, Stanford University
Natural gas is rapidly gaining importance in global energy markets. Prized for its relatively clean and efficient combustion, gas is becoming the fuel of choice for a wide array of uses, notably the generation of electric power. Natural gas is projected to be the fastest-growing major source of primary energy over the coming decades, with global consumption increasing nearly two-fold by 2030 (EIA 2004; IEA 2004). In the next few years, gas will surpass coal to become the world's second most important energy source; by 2050 gas could surpass oil to occupy the number one slot. Recent price increases do not fundamentally challenge the economic viability of this robust gas future.
There is plenty of gas to satisfy these visions of global gasification. The broadest measure of gas available totals about 350 trillion cubic meters (Tcm), or roughly 130 years at today's rate of consumption (USGS 2000). Even “proved reserves,” a narrower measure of just the gas that has been detected and is commercial to develop using today's technology, suggest that scarcity is unlikely to impede a global shift to gas. The widely referenced BP Statistical Review of World Energy reports 176 Tcm of proved gas worldwide, or nearly 70 years at current production levels (BP 2004).
The geographical, financial and political barriers to gas development, however, will be harder to clear.
Background. Behavioural syndromes (thought disturbance, social withdrawal, depressed behaviour and antisocial behaviour) offer a different perspective from that of symptomatic syndromes on the disability that may be associated with schizophrenia. Few studies have assessed their relationship with neuropsychological deficits. We hypothesized that these syndromes may represent behavioural manifestations of frontal-subcortical impairments, previously described in schizophrenia.
Method. Long-stay inpatients (n=54) and community patients (n=43) with enduring schizophrenia were assessed, using measures of symptoms and behaviour and tests of executive functioning. The relationship between syndromes and neuropsychological function was assessed using multiple regression and logistic regression analyses.
Results. Significant associations were found between performance on the spatial working memory task and the psychomotor poverty symptomatic syndrome, and between attentional set-shifting ability and both disorganization symptoms and the thought disturbance behavioural syndrome. These results were not explained by the effect of premorbid IQ, geographical location, length of illness or antipsychotic medication. Length of illness was an independent predictor of attentional set-shifting ability but not of working memory performance.
Conclusion. The specific relationship between negative symptoms and spatial working memory is consistent with involvement of the dorsolateral prefrontal cortex. The associations between difficulty with set-shifting ability and both disorganization symptoms and behaviours may reflect inability to generalize a rule that had been learned and impaired ability to respond flexibly. The specific relationship of illness duration to set-shifting ability may suggest progressive impairment on some executive tasks. The nature of these relationships and their neurobiological and rehabilitation implications are considered.
Improved management of mental illness and substance misuse comorbidity is a National Health Service priority, but little is known about its prevalence and current management.
To measure the prevalence of comorbidity among patients of community mental health teams (CMHTs) and substance misuse services, and to assess the potential for joint management.
Cross-sectional prevalence survey in four urban UK centres.
Of CMHT patients, 44% (95% CI 38.1-49.9) reported past-year problem drug use and/or harmful alcohol use; 75% (95% CI 68.2-80.2) of drug service and 85% of alcohol service patients (95% CI 74.2-931) had a past-year psychiatric disorder. Most comorbidity patients appear ineligible for cross-referral between services. Large proportions are not identified by services and receive no specialist intervention.
Comorbidity is highly prevalent in CMHT, drug and alcohol treatment populations, but may be difficult to manage by cross-referral psychiatric and substance misuse services as currently configured and resourced.