923 research outputs found
Genetic structure of the high dispersal Atlanto-Mediterreanean sea star Astropecten aranciacus revealed by mitochondrial DNA sequences and microsatellite loci
To investigate the impact of potential marine barriers on gene-flow in high dispersal marine invertebrates, we assessed the population genetic structure of the sea star Astropecten aranciacus. Samples were obtained from nine locations within the Atlantic and the Mediterranean Sea including populations east of the Siculo-Tunisian Strait. We obtained both DNA sequence data of the mitochondrial control region and genotype data at four microsatellite loci. Both markers were highly polymorphic and showed a great level of genetic diversity. Genetic differentiation between populations (F ST) was in general low, particularly for nuclear data, as is often the case in high dispersal marine invertebrates. Nevertheless, both marker sets indicated a significant genetic differentiation of the population from the island of Madeira to most other populations. Our results also demonstrate a clear pattern of isolation-by-distance supported by both mitochondrial and nuclear markers. Therefore, we conclude that larval dispersal of A. aranciacus is somewhat limited even within the basins of the Atlantic, the west Mediterranean and the east Mediterranean. Microsatellite loci further revealed genetic differentiation between the three basins; however, it is not clear whether this is truly caused by marine barriers. Genetic differentiation between basins might also be a result of isolation-by-distance allowing for any grouping to be significant as long as geographical neighbors are clustered together. Although levels of genetic differentiation were less pronounced in microsatellite data, both datasets were coherent and revealed similar patterns of genetic structure in A. aranciacu
Fundamental limitations for quantum and nano thermodynamics
The relationship between thermodynamics and statistical physics is valid in
the thermodynamic limit - when the number of particles becomes very large.
Here, we study thermodynamics in the opposite regime - at both the nano scale,
and when quantum effects become important. Applying results from quantum
information theory we construct a theory of thermodynamics in these limits. We
derive general criteria for thermodynamical state transformations, and as
special cases, find two free energies: one that quantifies the
deterministically extractable work from a small system in contact with a heat
bath, and the other that quantifies the reverse process. We find that there are
fundamental limitations on work extraction from nonequilibrium states, owing to
finite size effects and quantum coherences. This implies that thermodynamical
transitions are generically irreversible at this scale. As one application of
these methods, we analyse the efficiency of small heat engines and find that
they are irreversible during the adiabatic stages of the cycle.Comment: Final, published versio
A method for multi-hazard mapping in poorly known volcanic areas: an example from Kanlaon (Philippines)
Hazard mapping in poorly known volcanic areas is complex since much evidence of volcanic and non-volcanic hazards is often hidden by vegetation and alteration. In this paper, we propose a semi-quantitative method based on hazard event tree and multi-hazard map constructions developed in the frame of the FP7 MIAVITA project. We applied this method to the Kanlaon volcano (Philippines), which is characterized by poor geologic and historical records. We combine updated geological (long-term) and historical (short-term) data, building an event tree for the main types of hazardous events at Kanlaon and their potential frequencies. We then propose an updated multi-hazard map for Kanlaon, which may serve as a working base map in the case of future unrest. The obtained results extend the information already contained in previous volcanic hazard maps of Kanlaon, highlighting (i) an extensive, potentially active ~5 km long summit area striking north–south, (ii) new morphological features on the eastern flank of the volcano, prone to receiving volcanic products expanding from the summit, and (iii) important riverbeds that may potentially accumulate devastating mudflows. This preliminary study constitutes a basis that may help local civil defence authorities in making more informed land use planning decisions and in anticipating future risk/hazards at Kanlaon. This multi-hazard mapping method may also be applied to other poorly known active volcanoes
Study of molecular spin-crossover complex Fe(phen)2(NCS)2 thin films
We report on the growth by evaporation under high vacuum of high-quality thin
films of Fe(phen)2(NCS)2 (phen=1,10-phenanthroline) that maintain the expected
electronic structure down to a thickness of 10 nm and that exhibit a
temperature-driven spin transition. We have investigated the current-voltage
characteristics of a device based on such films. From the space charge-limited
current regime, we deduce a mobility of 6.5x10-6 cm2/V?s that is similar to the
low-range mobility measured on the widely studied
tris(8-hydroxyquinoline)aluminium organic semiconductor. This work paves the
way for multifunctional molecular devices based on spin-crossover complexes
‘Stumbling through’? Relationship-based social work practice in austere times
In recent times relationship-based practice has become a familiar term in social work practice and education. Despite its widespread adoption, how relationship-based practice is understood varies widely. Drawing on contemporary conceptualisations of the child and family and individuals as psychosocial subjects experiencing social suffering, this paper explores how current social work practice can be understood in the context of neoliberalism and austerity. Setting these ideas in an historical context helps to inform our understanding as to why social work seems to be the focus of sustained political discontent and scrutiny, making it difficult to retain a balanced relationship-based professional stance. Contemporary responses to the current challenges of everyday practice are outlined and the contribution of psychodynamic and systemic ideas to promoting relationship-based practice is explored. The paper concludes by considering how the concept of social systems as defences against anxiety can inform our understanding of the resistance amongst practitioners to relationship-based practice and emphasises the importance of reflective spaces and places for developing and maintaining integrated, mature relational approaches to practice which impact on practice at both the individual casework and social structural level
Recognising resilience factors among people living with HIV seeking to adopt
This article discusses the challenges faced by people living with HIV in the adoption process, looking especially at resilience factors. Resilience is framed in the context of HIV-related infertility that motivates people living with HIV to apply for adoption. The article draws on psychological definitions of resilience and presents four factors that promote and sustain it: individual strengths, good health management, social network and wider recognition in society. This is illustrated by a case study. The study emphasises that ‘the prospective adoptive child’ should always be at the centre of any assessments and encourages social workers to consider sensitive and inclusive practice when assessing prospective adopters living with HIV
The 3D Morphology of VY Canis Majoris. I The Kinematics of the Ejecta
Images of the complex circumstellar nebula associated with the famous red
supergiant VY CMa show evidence for multiple and asymmetric mass loss events
over the past 1000 yrs. Doppler velocities of the arcs and knots in the ejecta
showed that they are not only spatially distinct but also kinematically
separate from the surrounding diffuse material. In this paper we describe
second epoch HST/WFPC2 images to measure the transverse motions which when
combined with the radial motions provide a complete picture of the kinematics
of the ejecta including the total space motions and directions of the outflows.
Our results show that the arcs and clumps of knots are moving at different
velocities, in different directions, and at different angles relative to the
plane of the sky and to the star, confirming their origin from eruptions at
different times and from physically separate regions on the star. We conclude
that the morphology and kinematics of the arcs and knots are consistent with a
history of mass ejections not aligned with any presumed axis of symmetry. The
arcs and clumps represent relatively massive outflows and ejections of gas very
likely associated with large -- scale convective activity and magnetic fields.Comment: 20 pages, 10 figures, 5 table
Recommended from our members
Conceptual Soundness, Metric Development, Benchmarking, and Targeting for PATH Subprogram Evaluation
The objective of this study is to evaluate the conceptual soundness of the U.S. Department of Housing and Urban Development (HUD) Partnership for Advancing Technology in Housing (PATH) program's revised goals and establish and apply a framework to identify and recommend metrics that are the most useful for measuring PATH's progress. This report provides an evaluative review of PATH's revised goals, outlines a structured method for identifying and selecting metrics, proposes metrics and benchmarks for a sampling of individual PATH programs, and discusses other metrics that potentially could be developed that may add value to the evaluation process. The framework and individual program metrics can be used for ongoing management improvement efforts and to inform broader program-level metrics for government reporting requirements
The nature and culture of social work with children and families in long-term casework:Findings from a qualitative longitudinal study
Social work in the United Kingdom is preoccupied with what social workers cannot do due to having limited time to spend with service users. Yet remarkably little research has examined what social workers actually do, especially in long-term relationships. This paper draws from an ethnographic study of two social work departments in England that spent 15 months observing practice and organizational life. Our findings show that social work some of the time has a significant amount of involvement with some service users and the dominant view that relationship-based practice is rarely achieved is in need of some revision. However, families at one research site received a much more substantial, reliable overall service due to the additional input of family support workers and having a stable workforce who had their own desks and were co-located with managers in small team offices. This generated a much more supportive, reflective culture for social workers and service users than at the second site, a large open plan "hot-desking" office. Drawing on relational, systemic, and complexity theories, the paper shows how the nature of what social workers do and culture of practice are shaped by the interaction between available services, office designs, and practitioners', managers', and service users' experiences of relating together
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