1,849 research outputs found
Ultra-calcic Magmas Generated from Ca-depleted Mantle: an Experimental Study on the Origin of Ankaramites
Ultra-calcic ankaramitic magmas or melt inclusions are ubiquitous in arc, ocean-island and mid-ocean ridge settings. They are primitive in character (XMg > 0·65) and have high CaO contents (>14âwtâ%) and CaO/Al2O3 (>1·1). Experiments on an ankaramite from Epi, Vanuatu arc, demonstrate that its liquidus surface has only clinopyroxene at pressures of 15 and 20âkbar, with XCO2 in the volatile component from 0 to 0·86. The parental Epi ankaramite is thus not an unfractionated magma. However, forcing the ankaramite experimentally into saturation with olivine, orthopyroxene and spinel results in more magnesian, ultra-calcic melts with CaO/Al2O3 of 1·21-1·58. The experimental melts are not extremely Ca-rich but high in CaO/Al2O3 and in MgO (up to 18.5âwtâ%), and would evolve to high-CaO melts through olivine fractionation. Fractionation models show that the Epi parent magma can be derived from such ultra-calcic experimental melts through mainly olivine fractionation. We show that the experimental ultra-calcic melts could form through low-degree melting of somewhat refractory mantle. The latter would have been depleted by previous melt extraction, which increases the CaO/Al2O3 in the residue as long as some clinopyroxene remains residual. This finding corrects the common assumption that ultra-calcic magmas must come from a Ca-rich pyroxenite-type source. The temperatures necessary for the generation of ultra-calcic magmas are â„1330°C, and their presence would suggest melting regimes that are at the upper temperature end of previous interpretations made on the basis of picritic magma
A Simple Route towards High-Concentration Surfactant-Free Graphene Dispersions
A simple solvent exchange method is introduced to prepare high-concentration
and surfactant-free graphene liquid dispersion. Natural graphite flakes are
first exfoliated into graphene in dimethylformamide (DMF). DMF is then
exchanged by terpineol through distillation, relying on their large difference
in boiling points. Graphene can then be concentrated thanks to the volume
difference between DMF and terpineol. The concentrated graphene dispersions are
used to fabricate transparent conductive thin films, which possess comparable
properties to those prepared by more complex methods.Comment: 9 pages, 3 figure
Current cosmological constraints from a 10 parameter CMB analysis
We compute the constraints on a ``standard'' 10 parameter cold dark matter
(CDM) model from the most recent CMB and data and other observations, exploring
30 million discrete models and two continuous parameters. Our parameters are
the densities of CDM, baryons, neutrinos, vacuum energy and curvature, the
reionization optical depth, and the normalization and tilt for both scalar and
tensor fluctuations.
Our strongest constraints are on spatial curvature, -0.24 < Omega_k < 0.38,
and CDM density, h^2 Omega_cdm <0.3, both at 95%. Including SN 1a constraints
gives a positive cosmological constant at high significance.
We explore the robustness of our results to various assumptions. We find that
three different data subsets give qualitatively consistent constraints. Some of
the technical issues that have the largest impact are the inclusion of
calibration errors, closed models, gravity waves, reionization, nucleosynthesis
constraints and 10-dimensional likelihood interpolation.Comment: Replaced to match published ApJ version. More details added. 13 ApJ
pages. CMB movies and color figs at
http://www.hep.upenn.edu/~max/10par_frames.html or from [email protected]
Elective affinities of the Protestant ethic : Weber and the chemistry of capitalism
Peer reviewedPostprin
Tactics: Practical and Imagined
Since December 2017, a group of us (including Kim Solga, Sylvan Baker, Diana Damian Martin, Rebecca Hayes Laughton, and Katherine Low) have been convening working sessions at various schools and conferences that address the questions and problems animating this issue of RiDE. In this final article, a handful of our respondents from ASTR 2018 in San Diego ruminate upon, list, and re-member tactics they have used, or dreamed of using, to make it through the neoliberal academic day-to-day. Their thoughts are accompanied here by a handful of photos that document the documentation we produced at our first symposium
Spontaneous localization of bulk fields: the six-dimensional case
We study N=2 supersymmetric gauge theories with bulk and brane
fields charged under a U(1) gauge symmetry. Radiatively induced
Fayet-Iliopoulos terms lead to an instability of the bulk fields. We compute
the profile of the bulk zero modes and observe the phenomenon of spontaneous
localization towards the position of the branes. While this mechanism is quite
similar to the case, the mass spectrum of the excited Kaluza-Klein modes
shows a crucial difference.Comment: 23 pages, 3 figure file
Donât turn your back on the symptoms of psychosis : a proof-of-principle, quasi-experimental public health trial to reduce the duration of untreated psychosis in Birmingham, UK
Background: Reducing the duration of untreated psychosis (DUP) is an aspiration of international guidelines for first episode psychosis; however, public health initiatives have met with mixed results. Systematic reviews suggest that greater focus on the sources of delay within care pathways, (which will vary between healthcare settings) is needed to achieve sustainable reductions in DUP (BJP 198: 256-263; 2011).
Methods/Design: A quasi-experimental trial, comparing a targeted intervention area with a âdetection as usualâ area in the same city. A proof-ofâprinciple trial, no a priori assumptions are made regarding effect size; key outcome will be an estimate of the potential effect size for a definitive trial. DUP and number of new cases will be collected over an 18-month period in target and control areas and compared; historical data on DUP collected in both areas over the previous three years, will serve as a benchmark. The intervention will focus on reducing two significant DUP component delays within the overall care pathway: delays within the mental health service and help-seeking delay.
Discussion: This pragmatic trial will be the first to target known delays within the care pathway for those with a first episode of psychosis. If successful, this will provide a generalizable methodology that can be implemented in a variety of healthcare contexts with differing sources of delay.
Trial registration: http://www.controlled-trials.com/ISRCTN45058713
Keywords: Public mental health campaign, First-episode psychosis, Early detection, Duration of untreated psychosis, Youth mental healt
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