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Due to their extremely small luminosity compared to the stars they orbit, planets outside our own Solar System are extraordinarily difficult to detect directly in optical light. Careful photometric monitoring of distant stars, however, can reveal the presence of exoplanets via the microlensing or eclipsing effects they induce. The international PLANET collaboration is performing such monitoring using a cadre of semi-dedicated telescopes around the world. Their results constrain the number of gas giants orbiting 1–7 AU from the most typical stars in the Galaxy. Upgrades in the program are opening regions of “exoplanet discovery space” – toward smaller masses and larger orbital radii – that are inaccessible to the Doppler velocity technique.
Predictions of marine ice-sheet behaviour require models able to simulate grounding-line migration. We present results of an intercomparison experiment for plan-view marine ice-sheet models. Verification is effected by comparison with approximate analytical solutions for flux across the grounding line using simplified geometrical configurations (no lateral variations, no buttressing effects from lateral drag). Perturbation experiments specifying spatial variation in basal sliding parameters permitted the evolution of curved grounding lines, generating buttressing effects. The experiments showed regions of compression and extensional flow across the grounding line, thereby invalidating the boundary layer theory. Steady-state grounding-line positions were found to be dependent on the level of physical model approximation. Resolving grounding lines requires inclusion of membrane stresses, a sufficiently small grid size (<500 m), or subgrid interpolation of the grounding line. The latter still requires nominal grid sizes of <5 km. For larger grid spacings, appropriate parameterizations for ice flux may be imposed at the grounding line, but the short-time transient behaviour is then incorrect and different from models that do not incorporate grounding-line parameterizations. The numerical error associated with predicting grounding-line motion can be reduced significantly below the errors associated with parameter ignorance and uncertainties in future scenarios.
To determine perception v. actual intakes of energy-dense nutrient-poor ‘junk food’ (JF) and sugar-sweetened beverages (SSB) in young adults, using the mobile food record (mFR).
Before-and-after eating images using a 4 d mFR were assessed for standardised 600 kJ (143 kcal) servings of JF and SSB (excluding diet drinks). Participants reported their concern about the health aspects of their diet, perceptions and intentions regarding JF and SSB.
Perth, Western Australia.
Adults (n 246) aged 18–30 years.
The mean (sd) intake of JF+SSB was 3·7 (2·0) servings/d. Women thinking about drinking less SSB consumed more SSB servings/d (1·5 (1·2)) than men (0·7 (0·5); P<0·05) who were thinking about drinking less. Men not thinking about cutting down JF consumed more servings/d (4·6 (2·4)) than women (2·5 (0·7); P<0·01) who were not thinking about cutting down. Those who paid a lot of attention to the health aspects of their diet consumed less JF+SSB than those who took only a bit of notice (P<0·001), were not really thinking much about it (P<0·001) or who didn’t think at all about the health aspects of food (P<0·01).
Perceptions and attitudes regarding JF and SSB were associated with level of consumption. Those not thinking about cutting down their intake of these foods represent an important target group as they consume more than their peers. Further research is needed to identify how amenable young adults are to changing their intake, particularly given the lack of attention paid to the health aspects of their diet.
The Shang (c. 1500–1045 BC) and Zhou dynasties (c. 1045–771 BC) of China are famous for their sophisticated ritual bronze vessels. Sourcing the leaded tin-bronze has, however, proved to be a challenge. A new systematic approach to metal chemistry uses trace elements and isotopes to characterise the underlying circulation pattern. It reveals the complexity of the copper sources on which the late Shang capital at Anyang depended for its bronzes, suggesting the transport of copper from distant regions in the south, on the Yangtze, and from north-east China. The new interpretational system furthers our understanding of the network on which successive Chinese dynasties depended for copper, lead and tin, and attempts to give equal weight to the archaeological and chemical data.
Introduction/Innovation Concept: Rural and remote practice of emergency medicine presents unique challenges, particularly when faced with infrequently encountered cases and procedures. Simulation-based training is a valuable tool in the acquisition and maintenance of knowledge and skills; however, simulators are often located in larger centers and they are not widely outside these centers due to geographic, cost and time constraints. Mobile tele-simulation has the potential to overcome barriers but challenges such as comfort, technical issues and ability to teach desired content via tele-simulation must be addressed. We are developing a mobile-tele-simulation unit (MTU) prototype that will enable emergency medicine practitioners and trainees to access simulation-based instruction in rural and remote settings. Methods: Through application of a mixed-methods approach with input of a multidisciplinary team we are iteratively developing an MTU prototype to assess key factors in design and function, including: technical issues, environmental features, and human factors. The Delphi method is being used to collect input from experts on key design components and feedback is also being collected from trainees after participating in trial deployments of the MTU in different educational and environmental settings. Curriculum, Tool, or Material: The effective application of the MTU in a variety of learning settings will be optimized through ongoing evaluation in the iterative design cycle. Feedback to ensure a quality learning experience in the MTU will direct features of physical design and technical performance that can be applied in deployment of the unit. In addition, challenges to the delivery of module content and instructional modality/ features of lessons to be executed will be important considerations as we move toward developing content that can effectively be taught using the MTU. Conclusion: To ensure effective use of tele-simulation in the delivery of a meaningful simulation experience to rural and remote trainees a number of important challenges must be overcome. We describe our evolving multidisciplinary mixed-methods approach to develop an effective mobile tele-simulation unit.
Eta Carinae is one of the most massive observable binaries. Yet determination of its orbital and physical parameters is hampered by obscuring winds. However the effects of the strong, colliding winds changes with phase due to the high orbital eccentricity. We wanted to improve measures of the orbital parameters and to determine the mechanisms that produce the relatively brief, phase-locked minimum as detected throughout the electromagnetic spectrum. We conducted intense monitoring of the He ii λ4686 line in η Carinae for 10 months in the year 2014, gathering ~300 high S/N spectra with ground- and space-based telescopes. We also used published spectra at the FOS4 SE polar region of the Homunculus, which views the minimum from a different direction. We used a model in which the He ii λ4686 emission is produced by two mechanisms: a) one linked to the intensity of the wind-wind collision which occurs along the whole orbit and is proportional to the inverse square of the separation between the companion stars; and b) the other produced by the ‘bore hole’ effect which occurs at phases across the periastron passage. The opacity (computed from 3D SPH simulations) as convolved with the emission reproduces the behavior of equivalent widths both for direct and reflected light. Our main results are: a) a demonstration that the He ii λ4686 light curve is exquisitely repeatable from cycle to cycle, contrary to previous claims for large changes; b) an accurate determination of the longitude of periastron, indicating that the secondary star is ‘behind’ the primary at periastron, a dispute extended over the past decade; c) a determination of the time of periastron passage, at ~4 days after the onset of the deep light curve minimum; and d) show that the minimum is simultaneous for observers at different lines of sight, indicating that it is not caused by an eclipse of the secondary star, but rather by the immersion of the wind-wind collision interior to the inner wind of the primary.
Stonehenge is a site that continues to yield surprises. Excavation in 2009 added a new and unexpected feature: a smaller, dismantled stone circle on the banks of the River Avon, connected to Stonehenge itself by the Avenue. This new structure has been labelled ‘Bluestonehenge’ from the evidence that it once held a circle of bluestones that were later removed to Stonehenge. Investigation of the Avenue closer to Stonehenge revealed deep periglacial fissures within it. Their alignment on Stonehenge's solstitial axis (midwinter sunset–midsummer sunrise) raises questions about the early origins of this ritual landscape.
A review of the properties of Type II Cepheids and RV Tauri stars in the Magellanic Clouds is presented. In the behaviour of their light and colour curves, the RV Tauri stars appear to be a direct extension of the Type II Cepheids to longer periods. A single P – L – C relationship describes both the Type II Cepheids and RV Tauri stars in the LMC. The derived high intrinsic magnitudes for the RV Tauri variables supports the proposition that these objects are luminous stars evolving off the AGB. Preliminary analysis of the long time-series MACHO photometry indicates one star (MACHO*05:37:45.0–69:54:16) has an obvious ‘period-quadrupled’ periodicity, which is supporting evidence for a period-doubling bifurcation transition to chaotic pulsations.
We review the current status and future prospects of the PLANET collaboration, an international team of astronomers performing high-precision photometric monitoring of microlensing events. Our photometric precision and sampling is characterised and the suitability of the database for variable star studies is discussed. Preliminary results on K-giant stability are presented.
Early Iron Age pastoralists of the Eurasian steppes relied heavily on copper for weapons and ornaments, and new analysis of metal composition enables long-distance networks to be identified. Primary circulation from source areas where copper was mined can be distinguished alongside the secondary circulation of alloy types with high proportions of tin-bronze or leaded tin-bronze. The relative presence of trace elements, depleted during recycling events, provides a proxy for the flow of metal between regions. The localised seasonal movements characteristic of these mobile steppe societies underlie some of these patterns, but the evidence also indicates more extensive transfers, including the direct movement of finished objects over considerable distances.
We present improvement and confirmation of identified frequencies and pulsation modes for the γ Doradus star HD 189631. This work improves upon previous studies by incorporating a significant number of additional spectra and precise determination of frequencies. Four frequencies were identified for this star: 1.6774 ± 0.0002 d−1, 1.4174 ± 0.0002 d−1, 0.0714 ± 0.0002 d−1, and 1.8228 ± 0.0002 d−1 which were identified with the modes (l,m) = (1, +1), (1, +1), (2, −2), and (1, +1) respectively. These findings are in agreement with the most recent literature. The prevalence of (l,m) = (1, +1) modes in γ Doradus stars is starting to become apparent and we discuss this result.
Increased recognition of the business case for managing corporate impacts on the environment has helped drive increasingly detailed and quantified corporate environmental goals. Foremost among these are goals of no net loss (NNL) and net positive impact (NPI). We assess the scale and growth of such corporate goals. Since the first public, company-wide NNL/NPI goal in 2001, 32 companies have set similar goals, of which 18 specifically include biodiversity. Mining companies have set the most NNL/NPI goals, and the majority of those that include biodiversity, despite the generally lower total global impact of the mining industry on biodiversity compared to the agriculture or forestry industries. This could be linked to the mining industry's greater participation in best practice bodies, high-profile impacts, and higher profit margins per area of impact. The detail and quality of present goals vary widely. We examined specific NNL/NPI goals and assessed the extent to which their key components were likely to increase the effectiveness of these goals in benefiting biodiversity and managing business risk. Nonetheless, outcomes are more important than goals, and we urge conservationists to work with companies to both support and monitor their efforts to achieve increasingly ambitious environmental goals.
Excavations at the Easton Down long barrow were part of a wider programme of research into the Neolithic sequence and context of the Avebury area in north Wiltshire. The short barrow, on high chalk downland to the south-west of Avebury and the upper Kennet valley, and containing only a few inhumations according to Thurnam's 19th-century investigation, dates to the later 4th millennium BC. Test pits around the barrow produced very little struck flint, and virtually no colluvium in the adjacent dry valley to the west. The mound covered a thin calcareous turfline above a rubbly soil, probably formerly cultivated. The pre-barrow molluscan fauna, soil micromorphology and other environmental data indicate a clearance adjacent to woodland. In the secondary fill of the flanking ditches there is a succession from renewed woodland to open conditions in the Late Neolithic.
The Easton Down monument falls relatively late in the regional sequence of long barrow construction. Its setting was probably one of scattered, non-permanent clearances in woodland. Woodland was still widespread on the higher downland of the region in the middle of the Neolithic. Renewed and bigger-scale clearance towards the end of the Neolithic may be connected with the construction of very large monuments elsewhere in the region. The later prehistoric landscape became both more open and less diverse.
The gravity modes present in γ Doradus stars probe the deep stellar interiors and are thus of particular interest in asteroseismology. For the MUSICIAN programme at the University of Canterbury, we obtain extensive high-resolution echelle spectra of γ Dor stars from the Mt John University Observatory in New Zealand. We analyze these to obtain the pulsational frequencies and identify these with the multiple pulsational modes excited in the star. A summary of recent results from our spectroscopic mode-identification programme is given.
We carried out an extensive photometric and spectroscopic investigation of the SPB binary, HD 25558 (see Fig. 1 for the time and geographic distribution of the observations). The ~2000 spectra obtained at 13 observatories during 5 observing seasons, the ground-based multi-colour light curves and the photometric data from the MOST satellite revealed that this object is a double-lined spectroscopic binary with a very long orbital period of about 9 years. We determined the physical parameters of the components, and have found that both lie within the SPB instability strip. Accordingly, both components show line-profile variations consistent with stellar pulsations. Altogether, 11 independent frequencies and one harmonic frequency were identified in the data. The observational data do not allow the inference of a reliable orbital solution, thus, disentangling cannot be performed on the spectra. Since the lines of the two components are never completely separated, the analysis is very complicated. Nevertheless, pixel-by-pixel variability analysis of the cross-correlated line profiles was successful, and we were able to attribute all the frequencies to the primary or secondary component. Spectroscopic and photometric mode-identification was also performed for several of these frequencies of both binary components. The spectroscopic mode-identification results suggest that the inclination and rotation of the two components are rather different. While the primary is a slow rotator with ~6 d rotation period, seen at ~60° inclination, the secondary rotates fast with ~1.2 d rotation period, and is seen at ~20° inclination. Our spectropolarimetric measurements revealed that the secondary component has a magnetic field with at least a few hundred Gauss strength, while no magnetic field was detected in the primary.
The detailed analysis and results of this study will be published elsewhere.