Showing papers by "University of Hertfordshire published in 2006"
TL;DR: In this article, the authors present a catalog of nearby exoplanets, which contains the 172 known low-mass companions with orbits established through radial velocity and transit measurements around stars within 200 pc, including five previously unpublished ex-oplanets orbiting the stars HD 11964, HD 66428, HD 99109, HD 107148 and HD 164922.
Abstract: We present a catalog of nearby exoplanets. It contains the 172 known low-mass companions with orbits established through radial velocity and transit measurements around stars within 200 pc. We include five previously unpublished exoplanets orbiting the stars HD 11964, HD 66428, HD 99109, HD 107148, and HD 164922. We update orbits for 83 additional exoplanets, including many whose orbits have not been revised since their announcement, and include radial velocity time series from the Lick, Keck, and Anglo-Australian Observatory planet searches. Both these new and previously published velocities are more precise here due to improvements in our data reduction pipeline, which we applied to archival spectra. We present a brief summary of the global properties of the known exoplanets, including their distributions of orbital semimajor axis, minimum mass, and orbital eccentricity.
968 citations
Space Telescope Science Institute1, University of Hertfordshire2, University of Leicester3, Western Kentucky University4, European Southern Observatory5, University of California, Santa Cruz6, Liverpool John Moores University7, Norwegian Meteorological Institute8, University of Copenhagen9, Spanish National Research Council10, University of Nottingham11, California Institute of Technology12, Stockholm University13, University of Notre Dame14, Vanderbilt University15, Goddard Space Flight Center16, Marshall Space Flight Center17, Renaissance Technologies18, Lawrence Berkeley National Laboratory19, INAF20, University of Amsterdam21
TL;DR: In this article, the authors show that long-duration γ-ray bursts are associated with the most extremely massive stars and may be restricted to galaxies of limited chemical evolution. But they also show that the host galaxies of the long-drone bursts are significantly fainter and more irregular than the hosts of the core-collapse supernovae.
Abstract: When massive stars exhaust their fuel, they collapse and often produce the extraordinarily bright explosions known as core-collapse supernovae. On occasion, this stellar collapse also powers an even more brilliant relativistic explosion known as a long-duration γ-ray burst. One would then expect that these long γ-ray bursts and core-collapse supernovae should be found in similar galactic environments. Here we show that this expectation is wrong. We find that the γ-ray bursts are far more concentrated in the very brightest regions of their host galaxies than are the core-collapse supernovae. Furthermore, the host galaxies of the long γ-ray bursts are significantly fainter and more irregular than the hosts of the core-collapse supernovae. Together these results suggest that long-duration γ-ray bursts are associated with the most extremely massive stars and may be restricted to galaxies of limited chemical evolution. Our results directly imply that long γ-ray bursts are relatively rare in galaxies such as our own Milky Way.
901 citations
Kavli Institute for Theoretical Physics1, Trieste Astronomical Observatory2, Max Planck Society3, University of California, Santa Cruz4, Institute for Advanced Study5, Marshall Space Flight Center6, University of California, Berkeley7, University of Copenhagen8, University of Tokyo9, European Southern Observatory10, University of Chile11, University of Hertfordshire12, University of Leicester13, University of Amsterdam14, Lawrence Berkeley National Laboratory15, Chinese Academy of Sciences16, Spanish National Research Council17, University of Victoria18, University of Ferrara19, Space Telescope Science Institute20, Hiroshima University21, Florida State University College of Arts and Sciences22
TL;DR: The data, combined with radio and X-ray observations, suggest that XRF 060218 is an intrinsically weak and soft event, rather than a classical GRB observed off-axis, which extends the GRB–supernova connection to X-rays flashes and fainter supernovae, implying a common origin.
Abstract: Long-duration gamma-ray bursts (GRBs) are associated with type Ic supernovae(1) that are more luminous than average(2-5) and that eject material at very high velocities. Less-luminous supernovae were not hitherto known to be associated with GRBs, and therefore GRB - supernovae were thought to be rare events(6). Whether X-ray flashes - analogues of GRBs, but with lower luminosities and fewer gamma-rays - can also be associated with supernovae, and whether they are intrinsically 'weak' events or typical GRBs viewed off the axis of the burst(7), is unclear. Here we report the optical discovery and follow-up observations of the type Ic supernova SN 2006aj associated with X-ray flash XRF 060218. Supernova 2006aj is intrinsically less luminous than the GRB - supernovae, but more luminous than many supernovae not accompanied by a GRB. The ejecta velocities derived from our spectra are intermediate between these two groups, which is consistent with the weakness of both the GRB output(8) and the supernova radio flux(9). Our data, combined with radio and X-ray observations(8-10), suggest that XRF 060218 is an intrinsically weak and soft event, rather than a classical GRB observed off-axis. This extends the GRB - supernova connection to X-ray flashes and fainter supernovae, implying a common origin. Events such as XRF 060218 are probably more numerous than GRB - supernovae.
555 citations
TL;DR: Intermediate-fidelity simulation is a useful training technique that enables small groups of students to practise in a safe and controlled environment how to react adequately in a critical patient care situation and is little scientific evidence proving that such technology is better than more traditional techniques.
Abstract: The definitive version is available at www.blackwell-synergy.com.' Copyright Blackwell Publishing
534 citations
TL;DR: It is shown that weekly intravenous injections of morpholino phosphorodiamidate (morpholino) AONs induce expression of functional levels of dystrophin in body-wide skeletal muscles of the dystrophic mdx mouse, with resulting improvement in muscle function.
Abstract: For the majority of Duchenne muscular dystrophy (DMD) mutations, antisense oligonucleotide (AON)-mediated exon skipping has the potential to restore a functional protein. Here we show that weekly intravenous injections of morpholino phosphorodiamidate (morpholino) AONs induce expression of functional levels of dystrophin in body-wide skeletal muscles of the dystrophic mdx mouse, with resulting improvement in muscle function. Although the level of dystrophin expression achieved varies considerably between muscles, antisense therapy may provide a realistic hope for the treatment of a majority of individuals with DMD.
529 citations
TL;DR: The effect of various changes to the palladium catalyst during its stabilization in the course of the selective hydrogenation of ethyne-ethene mixtures (formation of hydride and carbide phases and of carbonaceous deposits) was reviewed in this paper.
Abstract: The effect of various changes to the palladium catalyst during its stabilization in the course of the selective hydrogenation of ethyne‐ethene mixtures (formation of hydride and carbide phases and of carbonaceous deposits) was reviewed. The deposits in the form of a carbonaceous overlayer on the palladium surface create sites at which selective ethyne hydrogenation to ethene can occur. The carbonaceous deposit on the support increases the selectivity to ethane formation by increasing the rate of ethene hydrogenation on support sites (spillover of hydrogen from metal to the support surface) and by decreasing the effective diffusivity of ethyne in the pores.
518 citations
TL;DR: The discovery of nonimidazole derivatives such as brain‐penetrating H3 antagonists has provided drugs that are in early‐phase clinical trials, possibly for application in obesity, and a variety of central nervous system disorders, such as memory, learning deficits and epilepsy.
Abstract: This article reviews the development of our knowledge of the actions of histamine which have taken place during the course of the 20th century. Histamine has been shown to have a key physiological role in the control of gastric acid secretion and a pathophysiological role in a range of allergic disorders. The synthesis of, and pharmacological studies on, selective agonists and antagonists has established the existence of four types of histamine receptor and histamine receptor antagonists have found very important therapeutic applications. Thus, in the 1940s, H(1)-receptor antagonists ('the antihistamines') yielded and still provide valuable treatment for allergic conditions such as hay fever and rhinitis. In the late 1970s and 1980s, H(2)-receptor antagonists (in the discovery of which the two authors were personally involved) revolutionised the treatment of peptic ulcer and other gastric acid-related diseases. The H(3)-receptor antagonists, although available since 1987, have been slower to find a therapeutic role. However, the discovery of nonimidazole derivatives such as brain-penetrating H(3) antagonists has provided drugs that are in early-phase clinical trials, possibly for application in obesity, and a variety of central nervous system disorders, such as memory, learning deficits and epilepsy. Finally, the most recently (1999) discovered H(4) receptor promises the potential to provide drugs acting on the immunological system with possible applications in asthma and inflammation.
474 citations
Stockholm University1, University of California, Berkeley2, University of Hertfordshire3, University of Copenhagen4, Space Telescope Science Institute5, Liverpool John Moores University6, University of Hawaii7, Heidelberg University8, University College Dublin9, Spanish National Research Council10, University of St Andrews11, Institut d'Astrophysique de Paris12, Institute for Advanced Study13, University of California, Santa Cruz14, European Southern Observatory15, University of Chile16, University of Amsterdam17
TL;DR: Zhang et al. as discussed by the authors reported that GRB 060614 was not accompanied by supernova emission down to limits hundreds of times fainter than the archetypal supernova SN 1998bw that accompanied GRB 980425, and faintter than any type Ic supernova ever observed.
Abstract: The tidy classification system that divided γ-ray bursts (GRBs) into long-duration busts (lasting more than two seconds) and short may have had its day. The final nail in its coffin may be GRB 060614. Discovered on 14 June 2006 by the Burst Alert Telescope on-board the Swift satellite, this burst was long, at 102 seconds, but as reported in a clutch of papers in this issue, it has a number of properties, including the absence of an accompanying supernova, that were previously considered diagnostic of a 'short' GRB. The hunt is now on for a classification system to take account of the diversity now apparent in GRBs. In the accompanying News & Views, Bing Zhang suggests that the answer may be to adopt a Type I/Type II classification similar to that used for supernovae. GRB 060505 and GRB 060614 were not accompanied by supernova emission down to limits hundreds of times fainter than the archetypal SN 1998bw that accompanied GRB 980425, and fainter than any type Ic supernova ever observed. It is now accepted that long-duration γ-ray bursts (GRBs) are produced during the collapse of a massive star1,2. The standard ‘collapsar’ model3 predicts that a broad-lined and luminous type Ic core-collapse supernova accompanies every long-duration GRB4. This association has been confirmed in observations of several nearby GRBs5–9. Here we report that GRB 060505 (ref. 10) and GRB 060614 (ref. 11) were not accompanied by supernova emission down to limits hundreds of times fainter than the archetypal supernova SN 1998bw that accompanied GRB 980425, and fainter than any type Ic supernova ever observed12. Multi-band observations of the early afterglows, as well as spectroscopy of the host galaxies, exclude the possibility of significant dust obscuration and show that the bursts originated in actively star-forming regions. The absence of a supernova to such deep limits is qualitatively different from all previous nearby long-duration GRBs and suggests a new phenomenological type of massive stellar death.
467 citations
University of British Columbia1, National Institute of Astrophysics, Optics and Electronics2, University of Kent3, University of Edinburgh4, California Institute of Technology5, Harvard University6, University of Cambridge7, University of Nottingham8, Imperial College London9, Cardiff University10, Durham University11, Cornell University12, Spanish National Research Council13, University of Sussex14, University College London15, Institute of Cosmology and Gravitation, University of Portsmouth16, University of Hertfordshire17, University of California, Irvine18, Subaru19, Liverpool John Moores University20, University of Padua21, University of Innsbruck22, Herzberg Institute of Astrophysics23
TL;DR: In this paper, the authors presented maps, source catalogue and number counts of the largest, most complete and unbiased extragalactic submillimetre survey: the 850-μm SCUBA Half-Degree Extragalactic Survey (SHADES).
Abstract: We present maps, source catalogue and number counts of the largest, most complete and unbiased extragalactic submillimetre survey: the 850-μm SCUBA Half-Degree Extragalactic Survey (SHADES). Using the Submillimetre Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT), SHADES mapped two separate regions of sky: the Subaru/XMM–Newton Deep Field (SXDF) and the Lockman Hole East (LH). Encompassing 93 per cent of the overall acquired data (i.e. data taken up to 2004 February 1), these SCUBA maps cover 720 arcmin2 with a rms noise level of about 2 mJy and have uncovered >100 submillimetre galaxies. In order to ensure the utmost robustness of the resulting source catalogue, data reduction was independently carried out by four subgroups within the SHADES team, providing an unprecedented degree of reliability with respect to other SCUBA catalogues available from the literature. Individual source lists from the four groups were combined to produce a robust 120-object SHADES catalogue; an invaluable resource for follow-up campaigns aiming to study the properties of a complete and consistent sample of submillimetre galaxies. For the first time, we present deboosted flux densities for each submillimetre galaxy found in a large survey. Extensive simulations and tests were performed separately by each group in order to confirm the robustness of the source candidates and to evaluate the effects of false detections, completeness and flux density boosting. Corrections for these effects were then applied to the data to derive the submillimetre galaxy source counts. SHADES has a high enough number of detected sources that meaningful differential counts can be estimated, unlike most submillimetre surveys which have to consider integral counts. We present differential and integral source number counts and find that the differential counts are better fit with a broken power law or a Schechter function than with a single power law; the SHADES data alone significantly show that a break is required at several mJy, although the precise position of the break is not well constrained. We also find that a 850-μm survey complete down to 2 mJy would resolve 20–30 per cent of the far-infrared background into point sources.
435 citations
TL;DR: In this article, the authors investigated the long-term changes in the bar morphology, specifically the evolution of the bar size, its vertical structure, and the exchange of angular momentum, and they showed that the prolonged growth of the stellar bar is mediated by continuous angular momentum transfer from the disk to the surrounding halo and that this angular momentum redistribution is resonant in nature.
Abstract: Evolution of stellar bars in disk galaxies is accompanied by dynamical instabilities and secular changes. Following the vertical buckling instability, the bars are known to weaken dramatically and develop a pronounced boxy/peanut shape when observed edge-on. Using high-resolution N-body simulations of stellar disks embedded in live axisymmetric dark matter halos, we have investigated the long-term changes in the bar morphology, specifically the evolution of the bar size, its vertical structure, and the exchange of angular momentum. We find that following the initial buckling, the bar resumes its growth from deep inside the corotation radius and follows the ultraharmonic resonance thereafter. We also find that this secular bar growth triggers a spectacular secondary vertical buckling instability that leads to the appearance of characteristic boxy/peanut/X-shaped bulges. The secular bar growth is crucial for the recurrent buckling to develop. Furthermore, the secondary buckling is milder, persists over a substantial period of time, ~3 Gyr, and can have observational counterparts. Overall, the stellar bars show recurrent behavior in their properties and evolve by increasing their linear and vertical extents, both dynamically and secularly. We also demonstrate explicitly that the prolonged growth of the bar is mediated by continuous angular momentum transfer from the disk to the surrounding halo and that this angular momentum redistribution is resonant in nature: a large number of lower resonances trap disk and halo particles, and this trapping is robust, in broad agreement with the earlier results in the literature.
418 citations
TL;DR: A two-dose regimen with an adjuvanted 30 microg inactivated H5N1 vaccine was safe and showed an immune response consistent with European regulatory requirements for licensure of seasonal influenza vaccine.
TL;DR: The aim of this paper is to describe the steps which the author followed to address issues of rigour in one qualitative research study conducted to explore the health visitor's role in identifying and working with vulnerable families in the community in relation to child protection.
Abstract: Over the last 20 years qualitative research methods have increased in popularity in the field of nursing research, yet critical issues of validity and reliability are often overlooked in published research reports. Thus, the aim of this paper is to describe the steps which the author followed to address issues of rigour in one qualitative research study. The study was conducted to explore the health visitor's role in identifying and working with vulnerable families in the community in relation to child protection. This paper will focus on how issues of validity and reliability were addressed in terms of qualitative interview data.
02 Mar 2006
TL;DR: The combined results of two studies that investigated how a robot should best approach and place itself relative to a seated human subject indicated that most subjects disliked a frontal approach, except for a small minority of females, and most subjects preferred to be approached from either the left or right side.
Abstract: This paper presents the combined results of two studies that investigated how a robot should best approach and place itself relative to a seated human subject. Two live Human Robot Interaction (HRI) trials were performed involving a robot fetching an object that the human had requested, using different approach directions. Results of the trials indicated that most subjects disliked a frontal approach, except for a small minority of females, and most subjects preferred to be approached from either the left or right side, with a small overall preference for a right approach by the robot. Handedness and occupation were not related to these preferences. We discuss the results of the user studies in the context of developing a path planning system for a mobile robot.
TL;DR: There was a modest increase in mortality in RA, mainly in the first 7 yrs, but treatment-related deaths were low, and risk factors included less favourable socio-economic status, markers of disease severity and diminished function within the first year.
Abstract: Objective. To examine the cause of death in a large UK inception cohort of rheumatoid arthritis (RA), and whether this was related to disease duration and severity, treatment effects or extra-articular features and complications of RA. Methods. Standard clinical, laboratory, radiological and socio-economic measures were recorded at baseline and yearly in an inception cohort started in nine centres in 1986. Date and the cause of death were based on death certificates and the comparisons made with age and sex matched population figures. Risk factors for mortality were identified from baseline measures of disease. Results. There were 459 deaths (32%) in 1429 patients followed for up to 18 yrs. Standard mortality ratio was 1.27. Survival was significantly lower in the first 7 yrs of RA. Excess mortality was seen in cardiovascular disease (31%), pulmonary fibrosis (4%) and lymphoma (2.3%). Baseline predictors for mortality were men, older age, poor function, lower socio-economic status, extra-articular features, comorbidity, rheumatoid factor, X-ray erosions, high-ESR and low-haemoglobin. Conclusion. There was a modest increase in mortality in RA, mainly in the first 7 yrs. Deaths from cardiovascular disease and pulmonary fibrosis were higher than expected, but treatment-related deaths were low. Risk factors included less favourable socio-economic status, markers of disease severity and diminished function within the first year.
TL;DR: There exists no alternative to the core Darwinian principles of variation, selection and inheritance to explain the evolution of complex evolving population systems.
Abstract: Complex evolving systems, consisting of populations of varied and replicating entities are found in both nature and human society. There exists no alternative to the core Darwinian principles of variation, selection and inheritance to explain the evolution of such systems. Neither the actual existence of human intentionality nor the hypothetical possibility of Lamarckian acquired character inheritance offers a barrier to the use of Darwinian principles. On the contrary, Darwinism is always required to complete the explanation. However, while Darwinian principles are always necessary to explain complex evolving population systems they are never sufficient on their own.
TL;DR: In this article, the effect of silicon (Si) on physiological attributes and nutritional status of maize (Zea mays cv. DK 647 F1) under water stress was studied in a pot experiment.
Abstract: The effect of silicon (Si) on physiological attributes and nutritional status of maize (Zea mays cv. DK 647 F1) under water stress was studied in a pot experiment. Treatments were (1) well watered (WW): 100% of FC (soil field capacity), (2) WW + Si1: 100% of FC + 1 mM Si, (3) WW + Si2: 100% of FC + 2 mM Si, (4) water stress (WS): 50% of FC, (5) WS + Si1: 50% of FC + 1 mM Si and (6) WS + Si2: 50% of FC + 2 mM Si. In the control treatment, plants were irrigated to field capacity (100% FC). Water stress was imposed by maintaining a moisture level equivalent to 50% of field capacity, whereas the well-watered pots (control) were maintained at full field capacity. Water stress was found to reduce the total dry matter (DM), chlorophyll content, and relative water content (RWC), but to increase proline accumulation and electrolyte leakage in maize plants. Both Si treatments largely improved the above physiological parameters, but levels remained significantly lower than the control (WW) values except for...
TL;DR: The hypothesis is that compounds showing a similar field point pattern are likely to bind at the same target site regardless of structure, which is illustrated using HIV NNRTI and thrombin ligands and validated across seven other targets.
Abstract: The paper describes the generation of four types of three-dimensional molecular field descriptors or 'field points' as extrema of electrostatic, steric, and hydrophobic fields. These field points are used to define the properties necessary for a molecule to bind in a characteristic way into a specified active site. The hypothesis is that compounds showing a similar field point pattern are likely to bind at the same target site regardless of structure. The methodology to test this idea is illustrated using HIV NNRTI and thrombin ligands and validated across seven other targets. From the in silico comparisons of field point overlays, the experimentally observed binding poses of these ligands in their respective sites can be reproduced from pairwise comparisons.
TL;DR: In this paper, the authors present a carefully selected sample of Swift GRBs, intended to estimate in an unbiased way the GRB mean redshift (z(mean)), constraints on the fraction of high-redshift bursts and an upper limit on the amount of heavily obscured afterglows.
Abstract: The exceptionally high luminosities of gamma-ray bursts (GRBs), gradually emerging as extremely useful probes of star formation, make them promising tools for exploration of the high-redshift Universe. Here we present a carefully selected sample of Swift GRBs, intended to estimate in an unbiased way the GRB mean redshift (z(mean)), constraints on the fraction of high-redshift bursts and an upper limit on the fraction of heavily obscured afterglows. We find that z(mean) = 2.8 and that at least 7% of GRBs originate at z > 5. In addition, consistent with pre-Swift observations, at most 20% of afterglows can be heavily obscured. The redshift distribution of the sample is qualitatively consistent with models where the GRB rate is proportional to the star formation rate in the Universe. We also report optical, near-infrared and X-ray observations of the afterglow of GRB 050814, which was seen to exhibit very red optical colours. By modelling its spectral energy distribution we find that z = 5.3 +/- 0.3. The high mean redshift of GRBs and their wide redshift range clearly demonstrates their suitability as efficient probes of galaxies and the intergalactic medium over a significant fraction of the history of the Universe. (Less)
TL;DR: In this paper, the authors present the results of deep Westerbork Synthesis Radio Telescope observations of neutral hydrogen in 12 nearby elliptical and lenticular Galaxi es, where they detect H I -both in regular discs as well as in clouds and tails offset from the host galaxy in 70% of the galaxies.
Abstract: We present the results of deep Westerbork Synthesis Radio Telescope observations of neutral hydrogen in 12 nearby elliptical and lenticular galaxi es. The selected objects come from a representative sample of nearby galaxies earlier studied at optical wavelengths with the integral-field spectrograph SAURON. They are field galaxies, or (in two cases) located in poor group environments. We detect H I - both in regular discs as well as in clouds and tails offset from the host galaxy - in 70% of the galaxies. This detection rate is much higher than in previous, shallower single-dish surveys, and is similar to that for the ionised gas. The results suggest that at faint detection levels the presence of H I is a relatively common characteristic of field early-type galaxies, confirming what was suggested t wenty years ago by Jura based on IRAS observations. The observed total H I masses range between a few times 10 6 M⊙ to just over 10 9 M⊙. The presence of regular disc-like structures is a situatio n as common as H I in offset clouds and tails around early-type galaxies. All g alaxies where H I isdetected also contain ionised gas, whereas no H I is found around galaxies without ionised gas. Galaxies with regular H I discs tend to have strong emission from ionised gas. In these cases, the similar kinematics of the neutral hydrogen and ionised gas suggest that they form one structure. The kinematical axis of the stellar component is nearly always misaligned with respect to that of the gas. We do not find a clear trend between the presence of H I and the global age of the stellar population or the global dynamical characteristics of t he galaxies. More specifically, H I detections are uniformly spread through the (V/σ, ǫ) diagram. If fast and slow rotators - galaxies with high and low specific angular momentum - represent th e relics of different formation paths, this does not appear in the presence and characterist ics of the H I. Our observations support the idea that gas accretion is common and does not happen exclusively in peculiar early-type galaxies. The links observed between the large-scale gas and the characteristics on the nuclear scale (e.g., the presence of kinematically de coupled cores, radio continuum emission etc.), suggest that for the majority of the cases th e gas is acquired through merging, but the lack of correlation with the stellar population age s uggests that smooth, cold accretion could be an alternative scenario, at least in some galaxies. In either cases, the data suggest that early-type galaxies continue to build their mass up to the pr esent.
TL;DR: The Antikythera Mechanism as discussed by the authors is a unique Greek geared device, constructed around the end of the second century bc. It is known that it calculated and displayed celestial information, particularly cycles such as the phases of the moon and a luni-solar calendar.
Abstract: The Antikythera Mechanism is a unique Greek geared device, constructed around the end of the second century bc. It is known1, 2, 3, 4, 5, 6, 7, 8, 9 that it calculated and displayed celestial information, particularly cycles such as the phases of the moon and a luni-solar calendar. Calendars were important to ancient societies10 for timing agricultural activity and fixing religious festivals. Eclipses and planetary motions were often interpreted as omens, while the calm regularity of the astronomical cycles must have been philosophically attractive in an uncertain and violent world. Named after its place of discovery in 1901 in a Roman shipwreck, the Antikythera Mechanism is technically more complex than any known device for at least a millennium afterwards. Its specific functions have remained controversial11, 12, 13, 14 because its gears and the inscriptions upon its faces are only fragmentary. Here we report surface imaging and high-resolution X-ray tomography of the surviving fragments, enabling us to reconstruct the gear function and double the number of deciphered inscriptions. The mechanism predicted lunar and solar eclipses on the basis of Babylonian arithmetic-progression cycles. The inscriptions support suggestions of mechanical display of planetary positions9, 14, 15, now lost. In the second century bc, Hipparchos developed a theory to explain the irregularities of the Moon's motion across the sky caused by its elliptic orbit. We find a mechanical realization of this theory in the gearing of the mechanism, revealing an unexpected degree of technical sophistication for the period.
TL;DR: In this paper, the authors investigated the impact of a robot's appearance on interactions involving four children with autism and found that the response of children towards the plain/robotic robot was notably more social and pro-active.
Abstract: This article studies the impact of a robot’s appearance on interactions involving four children with autism. This work is part of the Aurora project with the overall aim to support interaction skills in children with autism, using robots as ‘interactive toys’ that can encourage and mediate interactions. We follow an approach commonly adopted in assistive robotics and work with a small group of children with autism. This article investigates which robot appearances are suitable to encourage interactions between a robot and children with autism. The children’s levels of interaction with and response to different appearances of two types of robots are compared: a small humanoid doll, and a life-sized ‘Theatrical Robot’ (a mime artist behaving like a robot). The small humanoid robot appeared either as a human-like ‘pretty doll’ or as a ‘robot’ with plain features. The Theatrical Robot was presented either as an ordinary human, or with plain clothing and a featureless, masked face. The results of these trials clearly indicate the children’s preference in their initial response for interaction with a plain, featureless robot over the interaction with a human-like robot. In the case of the life-size Theatrical Robot, the response of children towards the plain/robotic robot was notably more social and pro-active. Implications of these results for our work on using robots as assistive technology for children with autism and their possible use in autism research are discussed.
01 Jan 2006
TL;DR: In this paper, the authors describe the REML-E-BLUP method and illustrate the method with some data on soil water content that exhibit a pronounced spatial trend, which is a special case of the linear mixed model where our data are modelled as the additive combination of fixed effects (e.g. the unknown mean, coefficients of a trend model), random effects (the spatially dependent random variation in the geostatistical context) and independent random error (nugget variation in geostatsistics).
Abstract: Geostatistical estimates of a soil property by kriging are equivalent to the best linear unbiased predictions (BLUPs). Universal kriging is BLUP with a fixed-effect model that is some linear function of spatial coordinates, or more generally a linear function of some other secondary predictor variable when it is called kriging with external drift. A problem in universal kriging is to find a spatial variance model for the random variation, since empirical variograms estimated from the data by method-of-moments will be affected by both the random variation and that variation represented by the fixed effects. The geostatistical model of spatial variation is a special case of the linear mixed model where our data are modelled as the additive combination of fixed effects (e.g. the unknown mean, coefficients of a trend model), random effects (the spatially dependent random variation in the geostatistical context) and independent random error (nugget variation in geostatistics). Statisticians use residual maximum likelihood (REML) to estimate variance parameters, i.e. to obtain the variogram in a geostatistical context. REML estimates are consistent (they converge in probability to the parameters that are estimated) with less bias than both maximum likelihood estimates and method-of-moment estimates obtained from residuals of a fitted trend. If the estimate of the random effects variance model is inserted into the BLUP we have the empirical BLUP or E-BLUP. Despite representing the state of the art for prediction from a linear mixed model in statistics, the REML-E-BLUP has not been widely used in soil science, and in most studies reported in the soils literature the variogram is estimated with methods that are seriously biased if the fixed-effect structure is more complex than just an unknown constant mean (ordinary kriging). In this paper we describe the REML-E-BLUP and illustrate the method with some data on soil water content that exhibit a pronounced spatial trend.
TL;DR: In this paper, the authors describe the REML-E-BLUP method and illustrate the method with some data on soil water content that exhibit a pronounced spatial trend, which is a special case of the linear mixed model where our data are modelled as the additive combination of fixed effects (e.g. the unknown mean, coefficients of a trend model), random effects (the spatially dependent random variation in the geostatistical context) and independent random error (nugget variation in geostatsistics).
Abstract: Geostatistical estimates of a soil property by kriging are equivalent to the best linear unbiased predictions (BLUPs). Universal kriging is BLUP with a fixed-effect model that is some linear function of spatial coordinates, or more generally a linear function of some other secondary predictor variable when it is called kriging with external drift. A problem in universal kriging is to find a spatial variance model for the random variation, since empirical variograms estimated from the data by method-of-moments will be affected by both the random variation and that variation represented by the fixed effects. The geostatistical model of spatial variation is a special case of the linear mixed model where our data are modelled as the additive combination of fixed effects (e.g. the unknown mean, coefficients of a trend model), random effects (the spatially dependent random variation in the geostatistical context) and independent random error (nugget variation in geostatistics). Statisticians use residual maximum likelihood (REML) to estimate variance parameters, i.e. to obtain the variogram in a geostatistical context. REML estimates are consistent (they converge in probability to the parameters that are estimated) with less bias than both maximum likelihood estimates and method-of-moment estimates obtained from residuals of a fitted trend. If the estimate of the random effects variance model is inserted into the BLUP we have the empirical BLUP or E-BLUP. Despite representing the state of the art for prediction from a linear mixed model in statistics, the REML-E-BLUP has not been widely used in soil science, and in most studies reported in the soils literature the variogram is estimated with methods that are seriously biased if the fixed-effect structure is more complex than just an unknown constant mean (ordinary kriging). In this paper we describe the REML-E-BLUP and illustrate the method with some data on soil water content that exhibit a pronounced spatial trend.
TL;DR: The definitive version of this article is available at www3.interscience.wiley.com. Copyright John Wiley & Sons [Full text of the article is not available in the UHRA] as discussed by the authors.
Abstract: ‘The definitive version is available at www3.interscience.wiley.com '. Copyright John Wiley & Sons [Full text of this article is not available in the UHRA]
TL;DR: In this article, the authors present spectral results from Chandra and XMM-Newton observations of a sample of 22 low-redshift radio galaxies and consider whether the core emission originates from the base of a relativistic jet, or an accretion flow, or contains contributions from both.
Abstract: We present spectral results from Chandra and XMM-Newton observations of a sample of 22 low-redshift (z < 0.1) radio galaxies and consider whether the core emission originates from the base of a relativistic jet, or an accretion flow, or contains contributions from both. We find correlations between the unabsorbed X-ray, radio, and optical fluxes and luminosities of FR I-type radio-galaxy cores, implying a common origin in the form of a jet. On the other hand, we find that the X-ray spectra of FR II-type radio galaxy cores are dominated by absorbed emission, with NH 1023 atoms cm-2, which is likely to originate in an accretion flow. We discuss several models that may account for the different nuclear properties of FR I- and FR II-type cores and also demonstrate that both heavily obscured, accretion-related and unobscured, jet-related components may be present in all radio galaxy nuclei. Any absorbed, accretion-related components in FR I-type galaxies have low radiative efficiencies.
TL;DR: The UKIRT Infrared Deep Sky Survey (UKIDSS) Early Data Release (EDR) as mentioned in this paper is a set of five large near-infrared surveys being undertaken with the United Kingdom Infrared Telescope Wide Field Camera (WFCAM).
Abstract: This paper defines the UKIRT Infrared Deep Sky Survey (UKIDSS) Early Data Release (EDR). UKIDSS is a set of five large near-infrared surveys being undertaken with the United Kingdom Infrared Telescope Wide Field Camera (WFCAM). The programme began in 2005 May and has an expected duration of 7 yr. Each survey uses some or all of the broad-band filter complement ZY JHK. The EDR is the first public release of data to the European Southern Observatory (ESO) community. All worldwide releases occur after a delay of 18 months from the ESO release. The EDR provides a small sample data set, ∼50 deg(2) (about 1 per cent of the whole of UKIDSS), that is a lower limit to the expected quality of future survey data releases. In addition, an EDR+ data set contains all EDR data plus extra data of similar quality, but for areas not observed in all of the required filters (amounting to ∼220 deg(2)). The first large data release, DR1, will occur in mid-2006. We provide details of the observational implementation, the data reduction, the astrometric and photometric calibration and the quality control procedures. We summarize the data coverage and quality (seeing, ellipticity, photometricity, depth) for each survey and give a brief guide to accessing the images and catalogues from the WFCAM Science Archive.
TL;DR: In this article, high-resolution, high signal-to-noise ratio (S/N) spectroscopy for the very metal poor star HD 122563 with the Subaru Telescope High Dispersion Spectrograph was obtained.
Abstract: We obtained high-resolution, high signal-to-noise ratio (S/N) spectroscopy for the very metal poor star HD 122563 with the Subaru Telescope High Dispersion Spectrograph. Previous studies have shown that this object has excesses of light neutron-capture elements, while its abundances of heavy ones are very low. In our spectrum, which covers 3070-4780 A of this object, 19 neutron-capture elements have been detected, including seven for the first time in this star (Nb, Mo, Ru, Pd, Ag, Pr, and Sm). Upper limits are given for five other elements including Th. The abundance pattern shows a gradually decreasing trend, as a function of atomic number, from Sr to Yb, which is quite different from those in stars with excesses of r-process elements. This abundance pattern of neutron-capture elements provides new strong constraints on the models of nucleosynthesis responsible for the very metal poor stars with excesses of light neutron-capture elements but without enhancement of heavy ones.
TL;DR: In this article, Chandra and XMM-Newtonspectral analysis of the radio galaxies and radio-loud quasars from the 3CRR sample in the redshift range 0.1 < z < 0.5 is presented.
Abstract: We present a Chandra and XMM-Newtonspectral analysis of the nuclei of the radio galaxies and radio-loud quasars from the 3CRR sample in the redshift range 0.1 < z < 0.5. In the range of radio luminosity sampled by these objects, mostly FRIIs, it has been clear for some time that a population of radio galaxies (‘low-excitation radio galaxies’) cannot easily participate in models that unify narrow-line radio galaxie s and broad-line objects. We show that low-excitation and narrow-line radio galaxies have systematically different nuclear Xray properties: while narrow-line radio galaxies universa lly show a heavily absorbed nuclear X-ray component, such a heavily absorbed component is rarely found in sources classed as low-excitation objects. Combining our data with the results of our earlier work on the z < 0.1 3CRR sources, we discuss the implications of this result for unified models, for the origins of mid-infrared emission from radio sources, and for the nature of the apparent FRI/FRII dichotomy in the X-ray. The lack of direct evidence for accretion-related X-ray emission in FRII LERGs leads us to argue that there is a strong possibility that some, or most, FRII LERGs accrete in a radiatively inefficient mode. However, our result s are also consistent with a model in which the accretion mode is the same for low- and high-excitation FRIIs, with the lower accretion luminosities in FRII LERGs attributed instead to more efficient radio luminosity production in those objects.
TL;DR: There was no additional benefit of adding specific spinal stabilization exercises to a conventional physiotherapy package for patients with recurrent low back pain and both groups showed improved physical functioning, reduced pain intensity, and an improvement in the physical component of quality of life.
Abstract: STUDY DESIGN. Pragmatic, multicentered randomized controlled trial, with 12-month follow-up. OBJECTIVE. To evaluate the effect of adding specific spinal stabilization exercises to conventional physiotherapy for patients with recurrent low back pain (LBP) in the United Kingdom. SUMMARY OF BACKGROUND DATA. Spinal stabilization exercises are a popular form of physiotherapy management for LBP, and previous small-scale studies on specific LBP subgroups have identified improvement in outcomes as a result. METHODS. A total of 97 patients (18-60 years old) with recurrent LBP were recruited. Stratified randomization was undertaken into 2 groups: "conventional," physiotherapy consisting of general active exercise and manual therapy; and conventional physiotherapy plus specific spinal stabilization exercises. Stratifying variables used were laterality of symptoms, duration of symptoms, and Roland Morris Disability Questionnaire score at baseline. Both groups received The Back Book, by Roland et al. Back-specific functional disability (Roland Morris Disability Questionnaire) at 12 months was the primary outcome. Pain, quality of life, and psychologic measures were also collected at 6 and 12 months. Analysis was by intention to treat. RESULTS. A total of 68 patients (70%) provided 12-month follow-up data. Both groups showed improved physical functioning, reduced pain intensity, and an improvement in the physical component of quality of life. Mean change in physical functioning, measured by the Roland Morris Disability Questionnaire, was -5.1 (95% confidence interval -6.3 to -3.9) for the specific spinal stabilization exercises group and -5.4 (95% confidence interval -6.5 to -4.2) for the conventional physiotherapy group. No statistically significant differences between the 2 groups were shown for any of the outcomes measured, at any time. CONCLUSIONS. Patients with LBP had improvement with both treatment packages to a similar degree. There was no additional benefit of adding specific spinal stabilization exercises to a conventional physiotherapy package for patients with recurrent LBP.
Space Telescope Science Institute1, University College London2, Kapteyn Astronomical Institute3, Louisiana State University4, University of Manchester5, University of Missouri6, University of Hertfordshire7, Monterey Institute for Research in Astronomy8, University of Arizona9, McMaster University10, University of Cambridge11
TL;DR: Observations of the Type II supernova 2003gd show that dust formation in supernova ejecta can be efficient and that massive-star supernovae could have been major dust producers throughout the history of the universe.
Abstract: We present late-time optical and mid-infrared observations of the Type II supernova 2003gd in the galaxy NGC 628. Mid-infrared excesses consistent with cooling dust in the ejecta are observed 499 to 678 days after outburst and are accompanied by increasing optical extinction and growing asymmetries in the emission-line profiles. Radiative-transfer models show that up to 0.02 solar masses of dust has formed within the ejecta, beginning as early as 250 days after outburst. These observations show that dust formation in supernova ejecta can be efficient and that massive-star supernovae could have been major dust producers throughout the history of the universe.