4,810 research outputs found
Generation of internal stress and its effects
Internal stresses may be generated continually in many polycrystalline materials. Their existence is manifested by changes in crystal defect concentration and arrangement, by surface observations, by macroscopic shape changes and particularly by alteration of mechanical properties when external stresses are simultaneously imposed
High pressure Ca-VI phase between 158-180 GPa: Stability, electronic structure and superconductivity
We have performed ab initio calculations for new high-pressure phase of Ca-VI
between 158-180 GPa. The study includes elastic parameters of mono- and
poly-crystalline aggregates, electronic band structure, lattice dynamics and
superconductivity. The calculations show that the orthorhombic Pnma structure
is mechanically and dynamically stable in the pressure range studied. The
structure is superconducting in the entire pressure range and the calculated Tc
(~25K) is maximum at ~172 GPa, where the transfer of charges from 4s to 3d may
be thought to be completed.Comment: 8 pages, 4 figures; PACS number(s): 74.70.Ad, 62.20.de, 71.20.-b,
74.20.Pq, 74.25.Kc, 74.62.Fj; Keywords: Calcium; High pressure; Electronic
band structure; Phonon spectrum; Elastic constants; Superconducto
Chiral Reductions in the Salam-Sezgin Model
Reductions from six to four spacetime dimensions are considered for a class
of supergravity models based on the six-dimensional Salam-Sezgin model, which
is a chiral theory with a gauged U(1) R-symmetry and a positive scalar-field
potential. Reduction on a sphere and monopole background of such models
naturally yields four-dimensional theories without a cosmological constant. The
question of chirality preservation in such a reduction has been a topic of
debate. In this article, it is shown that the possibilities of dimensional
reduction bifurcate into two separate consistent dimensional-reduction schemes.
One of these retains the massless SU(2) vector gauge triplet arising from the
sphere's isometries, but it produces a non-chiral four-dimensional theory. The
other consistent scheme sets to zero the SU(2) gauge fields, but retains the
gauged U(1) from six dimensions and preserves chirality although the U(1) is
spontaneously broken. Extensions of the Salam-Sezgin model to include larger
gauge symmetries produce genuinely chiral models with unbroken gauge
symmetries.Comment: 37 page
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Serving GODAE Data and Products to the Ocean Community
The Global Ocean Data Assimilation Experiment (GODAE [http://
www.godae.org]) has spanned a decade of rapid technological development. The ever-increasing volume and diversity of oceanographic data produced by in situ instruments, remote-sensing platforms, and computer simulations have driven
the development of a number of innovative technologies that are essential for connecting scientists with the data that they need. This paper gives an overview of the technologies that have been developed and applied in the course of GODAE, which now provide users of oceanographic data with the capability to discover, evaluate, visualize, download, and analyze data from all over the world. The key to this
capability is the ability to reduce the inherent complexity of oceanographic data by providing a consistent, harmonized view of the various data products. The challenges of data serving have been addressed over the last 10 years through the cooperative skills and energies of many individuals
Bringing the Inside Out and the Outside in: The Therapeutic Relationship in Compassion Focused Therapy Chairwork
Chairwork is a central component in Compassion Focused Therapy (CFT). Despite its importance, there has been no prior research on the relational factors underpinning the application of chairwork in CFT. There is also a general paucity of research on the role of the therapeutic relationship in chairwork across modalities. This paper analyses data from interviews with 21 clients following a CFT chairwork intervention to ascertain how relational factors influenced their experience of this method. An Interpretative Phenomenological Analysis (IPA) found three main themes: 1) direction and coaching during enactment; 2) externalisation: bringing the inside out and outside in; 3) regulation and trust: the relational requirements to âlet goâ. The implications of these findings, both for the delivery and training of chairwork, are then discussed in the context of CFT
Correction to "Long-term and recent changes in sea level in the Falkland Islands"
In the paper âLong-term and recent changes in sea level in the Falkland Islandsâ by P. L. Woodworth et al. (Journal of Geophysical Research, 115, C09025, doi:10.1029/2010JC006113, 2010), in paragraph 47 we adopted a value of â0.52 mm/yr for the estimated rate of present-day sea level change in the Falkland Islands due to glacial isostatic adjustment (GIA). This value was used to remove the contributions of GIA to our measurements of historical and recent rates of sea level change. However, it was based on a misreading of the data file of Peltier [2004] on the Permanent Service for Mean Sea Level Web site (http://www.psmsl.org/train_and_info/geo_signals/gia/peltier). More reasonable values to apply to the observed changes since the mid-nineteenth century and in recent years would be â0.69 and â0.61 mm/yr respectively. Consequently, the long-term rate of sea level change between 1842 and the early 1980s, after correction for air pressure effects and for GIA, reported as +0.75 ± 0.35 mm/yr in paragraphs 1, 47, 55, and 61 should be +0.92 ± 0.35 mm/yr, the corresponding rate between 1842 and the midpoint of recent data of 1.06 ± 0.22 mm/yr in paragraphs 48 and 55 should be 1.23 ± 0.22 mm/yr, and the corresponding rate since 1992 reported as 2.51 ± 0.58 mm/yr in paragraphs 1 and 52 becomes 2.60 ± 0.58 mm/yr. The middle of paragraph 63 becomes âThe Stanley data suggest that the rate of change of sea level in East Falkland since 1992 has been approximately 2.6 mm/yr, a rate supported by information from satellite altimetry.â These small GIA model corrections have no bearing on the main findings of our paper on the difference in the rates of sea level change between the historical (1842 to present-day) and recent (last 2 decades) epoch
Integrating physical activity promotion into UK medical school curricula: testing the feasibility of an educational tool developed by the Faculty of Sports and Exercise Medicine.
Background: At present education on exercise medicine and physical activity (PA) promotion does not feature heavily within the medical curriculum. Objectives: The purpose of this study was to test the feasibility of a self-directed educational tool (Faculty of Sports and Exercise Medicine (FSEM) exercise prescription booklet) on medical students' understanding of PA in disease management. Methods: Students from 22 UK medical schools were invited to complete a brief online questionnaire before and after being provided access to the FSEM exercise prescription booklet. Results: A total of 205 students responded to the open invitation to participate. At baseline 59% of students agreed that PA promotion was an important part of a doctor's job with 86% agreeing that PA was important in the prevention of disease. However, confidence to prescribe PA and knowledge of chief medical officer's adult PA guidelines was low. Following use of the FSEM booklet students' (n=53) knowledge of PA guidelines and confidence to advise patients about PA significantly improved (p<0.05). Correct response answers to case scenarios covering PA in disease management (specifically osteoarthritis and cancer) also improved (32% and 44% increase, respectively, p<0.01). Conclusion: Self-guided educational tools have the potential to improve the exercise prescription skills of undergraduate medical students. Future research should compare different methods of delivering education on PA within medical schools to determine the most effective means of integrating PA into the curriculum
Theory of linear sweep voltammetry with diffuse charge: Unsupported electrolytes, thin films, and leaky membranes
Linear sweep and cyclic voltammetry techniques are important tools for electrochemists and have a variety of applications in engineering. Voltammetry has classically been treated with the Randles-Sevcik equation, which assumes an electroneutral supported electrolyte. In this paper, we provide a comprehensive mathematical theory of voltammetry in electrochemical cells with unsupported electrolytes and for other situations where diffuse charge effects play a role, and present analytical and simulated solutions of the time-dependent Poisson-Nernst-Planck equations with generalized Frumkin-Butler-Volmer boundary conditions for a 1:1 electrolyte and a simple reaction. Using these solutions, we construct theoretical and simulated current-voltage curves for liquid and solid thin films, membranes with fixed background charge, and cells with blocking electrodes. The full range of dimensionless parameters is considered, including the dimensionless Debye screening length (scaled to the electrode separation), Damkohler number (ratio of characteristic diffusion and reaction times), and dimensionless sweep rate (scaled to the thermal voltage per diffusion time). The analysis focuses on the coupling of Faradaic reactions and diffuse charge dynamics, although capacitive charging of the electrical double layers is also studied, for early time transients at reactive electrodes and for nonreactive blocking electrodes. Our work highlights cases where diffuse charge effects are important in the context of voltammetry, and illustrates which regimes can be approximated using simple analytical expressions and which require more careful consideration
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