6,025 research outputs found
Prospects for Extrasolar "Earths" in Habitable Zones
We have shown that Earth-mass planets could survive in variously restricted
regions of the habitable zones (HZs) of most of a sample of nine of the 102
main-sequence exoplanetary systems confirmed by 19 November 2003. In a
preliminary extrapolation of our results to the other systems, we estimate that
roughly a half of these systems could have had an Earth-mass planet confined to
the HZ for at least the most recent 1000 Ma. The HZ migrates outwards during
the main-sequence lifetime, and so this proportion varies with stellar age.
About two thirds of the systems could have such a planet confined to the HZ for
at least 1000 Ma at sometime during the main-sequence lifetime. Clearly, these
systems should be high on the target list for exploration for terrestrial
planets. We have reached this conclusion by launching putative Earth-mass
planets in various orbits and following their fate with mixed-variable
symplectic and hybrid integrators. Whether the Earth-mass planets could form in
the HZs of the exoplanetary systems is an urgent question that needs further
study.Comment: 7 pages, 2 figure
Observing the Geometry of Warped Compactification via Cosmic Inflation
Using DBI inflation as an example, we demonstrate that the detailed geometry
of warped compactification can leave an imprint on the cosmic microwave
background (CMB). We compute CMB observables for DBI inflation in a generic
class of warped throats and find that the results (such as the sign of the tilt
of the scalar perturbations and its running) depend sensitively on the precise
shape of the warp factor. In particular, we analyze the warped deformed
conifold and find that the results can differ from those of other warped
geometries, even when these geometries approximate well the exact metric of the
warped deformed conifold.Comment: 4 pages, 3 figures. v2: References and clarifications adde
Implementing a BIM collaborative workflow in the UK construction market
BIM Level 2, as defined by the UK government, sets out processes and standards that formalise and regulate the collaborative methods for producing, sharing and exchanging information during different stages of any construction project. For overseas organisations that are looking to invest in the UK construction market, they will most certainly need to consider developing their understanding and ability related to BIM in order to enable developing their capability and competency to compete. This paper presents a case study that focuses on the implementation of collaborative based BIM workflow at a large Chinese engineering and construction organisation, which has recently established operations in the UK. The BIM implementation has been achieved under a Knowledge Exchange Partnership framework between the organisation and an academic institution in the UK. The main aim for this partnership project was to transform the organisationâs traditional workflow to achieve a BIM based collaborative workflow, and to comply with BIM Level 2 requirements. The case study has been achieved by adopting an action research methodology, whereby the project affiliate was an active part of the implementation project and was managing and coordinating the partnership project between the organisation and academic partner. Results to date from the project will be documented in this paper. This includes highlighting key challenges, adopted strategies and tactics to overcome the obstacles, pockets of improvements and potential areas for future development
ExoMol molecular line lists - XVII The rotation-vibration spectrum of hot SO
Sulphur trioxide (SO) is a trace species in the atmospheres of the Earth
and Venus, as well as well as being an industrial product and an environmental
pollutant. A variational line list for SO, named UYT2, is
presented containing 21 billion vibration-rotation transitions. UYT2 can be
used to model infrared spectra of SO at wavelengths longwards of 2 m
( cm) for temperatures up to 800 K. Infrared absorption
cross sections are also recorded at 300 and 500 C are used to validate the UYT2
line list. The intensities in UYT2 are scaled to match the measured cross
sections. The line list is made available in electronic form as supplementary
data to this article and at \url{www.exomol.com}.Comment: 15 pages, 10 figures, 9 tables MNRAS submitte
Designing Secure Ethereum Smart Contracts: A Finite State Machine Based Approach
The adoption of blockchain-based distributed computation platforms is growing
fast. Some of these platforms, such as Ethereum, provide support for
implementing smart contracts, which are envisioned to have novel applications
in a broad range of areas, including finance and Internet-of-Things. However, a
significant number of smart contracts deployed in practice suffer from security
vulnerabilities, which enable malicious users to steal assets from a contract
or to cause damage. Vulnerabilities present a serious issue since contracts may
handle financial assets of considerable value, and contract bugs are
non-fixable by design. To help developers create more secure smart contracts,
we introduce FSolidM, a framework rooted in rigorous semantics for designing
con- tracts as Finite State Machines (FSM). We present a tool for creating FSM
on an easy-to-use graphical interface and for automatically generating Ethereum
contracts. Further, we introduce a set of design patterns, which we implement
as plugins that developers can easily add to their contracts to enhance
security and functionality
Plant neighborhood effects on herbivory: Damage is both density and frequency dependent
© 2015 by the Ecological Society of America. Neighboring plants can affect the likelihood that a focal plant is attacked by herbivores. Both the density of conspecific neighbors (resource concentration or dilution effects) and the relative density of heterospecific neighbors (associational effects or effects of neighbor frequency) within the local neighborhood can affect herbivore load and plant damage. Understanding how these neighborhood effects influence processes such as plant competition or natural selection on plant resistance traits will require knowing how both plant density and frequency affect damage, but previous studies have generally confounded density and frequency effects. In this study, we independently manipulated the absolute density and frequency (i.e., relative density) of two plant species (Solanum carolinense and Solidago altissima) to characterize neighborhood composition effects on S. carolinense damage by herbivores, providing the first picture of how both density and frequency of neighbors influence damage in a single system. We found both a positive effect of S. carolinense density on S. carolinense damage (a resource concentration effect) and a nonlinear effect of S. altissima frequency on S. carolinense damage (associational susceptibility). If these types of patterns are common in nature, future studies seeking to understand neighborhood effects on damage need to incorporate both density and frequency effects and capture any nonlinear effects by selecting a range of values rather than focusing on only a pair of densities or frequencies. This type of data on neighborhood effects will allow us to understand the contribution of neighborhood effects to population-level processes such as competition, the evolution of plant resistance to herbivores, and yield gains in agricultural crop mixtures
Whole home exercise intervention for depression in older care home residents (the OPERA study) : a process evaluation
Background:
The âOlder Peopleâs Exercise intervention in Residential and nursing Accommodationâ (OPERA) cluster randomised trial evaluated the impact of training for care home staff together with twice-weekly, physiotherapist-led exercise classes on depressive symptoms in care home residents, but found no effect. We report a process evaluation exploring potential explanations for the lack of effect.
Methods:
The OPERA trial included over 1,000 residents in 78 care homes in the UK. We used a mixed methods approach including quantitative data collected from all homes. In eight case study homes, we carried out repeated periods of observation and interviews with residents, care staff and managers. At the end of the intervention, we held focus groups with OPERA research staff. We reported our first findings before the trial outcome was known.
Results:
Homes showed large variations in activity at baseline and throughout the trial. Overall attendance rate at the group exercise sessions was low (50%). We considered two issues that might explain the negative outcome: whether the intervention changed the culture of the homes, and whether the residents engaged with the intervention. We found low levels of staff training, few home champions for the intervention and a culture that prioritised protecting residents from harm over encouraging activity. The trial team delivered 3,191 exercise groups but only 36% of participants attended at least 1 group per week and depressed residents attended significantly fewer groups than those who were not depressed. Residents were very frail and therefore most groups only included seated exercises.
Conclusions:
The intervention did not change the culture of the homes and, in the case study homes, activity levels did not change outside the exercise groups. Residents did not engage in the exercise groups at a sufficient level, and this was particularly true for those with depressive symptoms at baseline. The physical and mental frailty of care home residents may make it impossible to deliver a sufficiently intense exercise intervention to impact on depressive symptoms
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