1,299 research outputs found

    Scaling-up permafrost thermal measurements in western Alaska using an ecotype approach

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    Permafrost temperatures are increasing in Alaska due to climate change and in some cases permafrost is thawing and degrading. In areas where degradation has already occurred the effects can be dramatic, resulting in changing ecosystems, carbon release, and damage to infrastructure. However, in many areas we lack baseline data, such as subsurface temperatures, needed to assess future changes and potential risk areas. Besides climate, the physical properties of the vegetation cover and subsurface material have a major influence on the thermal state of permafrost. These properties are often directly related to the type of ecosystem overlaying permafrost. In this paper we demonstrate that classifying the landscape into general ecotypes is an effective way to scale up permafrost thermal data collected from field monitoring sites. Additionally, we find that within some ecotypes the absence of a moss layer is indicative of the absence of near-surface permafrost. As a proof of concept, we used the ground temperature data collected from the field sites to recode an ecotype land cover map into a map of mean annual ground temperature ranges at 1 m depth based on analysis and clustering of observed thermal regimes. The map should be useful for decision making with respect to land use and understanding how the landscape might change under future climate scenarios

    Concept definition study for recovery of tumbling satellites. Volume 1: Executive summary, study results

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    The first assessment is made of the design requirements and conceptual definition of a front end kit to be transported on the currently defined Orbital Maneuvering Vehicle (OMV) and the Space Transportation System Shuttle Orbiter, to conduct remote, teleoperated recovery of disabled and noncontrollable, tumbling satellites. Previous studies did not quantify the dynamic characteristics of a tumbling satellite, nor did they appear to address the full spectrum of Tumbling Satellite Recovery systems requirements. Both of these aspects are investigated with useful results

    Sex-Specific Differences in Shoaling Affect Parasite Transmission in Guppies

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    Background: Individuals have to trade-off the costs and benefits of group membership during shoaling behaviour. Shoaling can increase the risk of parasite transmission, but this cost has rarely been quantified experimentally. Guppies (Poecilia reticulata) are a model system for behavioural studies, and they are commonly infected by gyrodactylid parasites, notorious fish pathogens that are directly transmitted between guppy hosts. Methodology/Principal Findings:Parasite transmission in single sex shoals of male and female guppies were observed using an experimental infection of Gyrodactylus turnbulli. Parasite transmission was affected by sex-specific differences in host behaviour, and significantly more parasites were transmitted when fish had more frequent and more prolonged contact with each other. Females shoaled significantly more than males and had a four times higher risk to contract an infection. Conclusions/Significance: Intersexual differences in host behaviours such as shoaling are driven by differences in natural and sexual selection experienced by both sexes. Here we show that the potential benefits of an increased shoaling tendency are traded off against increased risks of contracting an infectious parasite in a group-living species

    Concept definition study for recovery of tumbling satellites. Volume 2: Supporting research and technology report

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    A number of areas of research and laboratory experiments were identified which could lead to development of a cost efficient remote, disable satellite recovery system. Estimates were planned of disabled satellite motion. A concept is defined as a Tumbling Satellite Recovery kit which includes a modular system, composed of a number of subsystem mechanisms that can be readily integrated into varying combinations. This would enable the user to quickly configure a tailored remote, disabled satellite recovery kit to meet a broad spectrum of potential scenarios. The capability was determined of U.S. Earth based satellite tracking facilities to adequately determine the orientation and motion rates of disabled satellites

    Entangled two atoms through different couplings and the thermal noise

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    The entanglement of two atoms is studied when the two atoms are coupled to a single-mode thermal field with different couplings. The different couplings of two atoms are in favor of entanglement preparation: it not only makes the case of absence entanglement with same coupling appear entanglement, but also enhances the entanglement with the increasing of the relative difference of two couplings. We also show that the diversity of coupling can improved the critical temperature. If the optical cavity is leaky during the time evolution, the dissipative thermal environment is benefit to produce the entanglement.Comment: 4 pages, 4 figure

    The beta-decay of 22Al

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    In an experiment performed at the LISE3 facility of GANIL, we studied the decay of 22Al produced by the fragmentation of a 36Ar primary beam. A beta-decay half-life of 91.1 +- 0.5 ms was measured. The beta-delayed one- and two-proton emission as well as beta-alpha and beta-delayed gamma decays were measured and allowed us to establish a partial decay scheme for this nucleus. New levels were determined in the daughter nucleus 22Mg. The comparison with model calculations strongly favours a spin-parity of 4+ for the ground state of 22Al

    The support and information needs of adolescents and young adults with cancer when active treatment ends

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    Background: The end of active treatment is a period of high stress for young people with cancer, but limited literature exists about their information and support needs during this phase. This study aimed to understand the needs of young people with cancer, how these needs are currently being met, and how best to provide information and support at the end of active treatment. Methods: This was a multi-stage, mixed methods study exploring the end of treatment experience from the perspectives of young people, and the healthcare professionals caring for them. Semi-structured interviews were undertaken with healthcare professionals, which informed a survey administered nationally. Subsequently, semi-structured interviews were conducted with young people. These combined results informed a co-design workshop to develop recommendations. Results: Telephone interviews were conducted with 12 healthcare professionals and 49 completed the online survey. A total of 11 young people aged 19–26 years (female = 8; 73%) were interviewed. The stakeholder workshop was attended by both healthcare professionals (n = 8) and young people (n = 3). At the end of treatment young people experience numerous ongoing physical issues including pain, fatigue and insomnia; in addition to a range of psychosocial and emotional issues including anxiety, fear of recurrence and isolation. The top three priorities for end of treatment care were: earlier provision and preparation around on-going impact of cancer and cancer treatment; standardised and continued follow-up of young people’s emotional well-being; and development of more information and resources specific to young people. Conclusion The access and availability of appropriate information and sources of support at the end of treatment is variable and inequitable. Young people’s needs would be more effectively met by timely, structured and accessible information, and support provision at the end of treatment to both prepare and enable adaptation across their transition to living with and beyond cancer. This will require both organisational and practical adjustments in care delivery, in addition to a renewed and updated understanding of what the ‘end of treatment’ transition process means
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