463 research outputs found
Deciphering orogenic evolution
International audienceDeciphering orogenic evolution requires the integration of a growing number of geological and geophysical techniques on various spatial and temporal scales. Contrasting visions of mountain building and lithospheric deformation have been proposed in recent years. These models depend on the respective roles assigned to the mantle, the crust or the sediments. This article summarizes the contents of the Special Issue dedicated to 'Geodynamics and Orogenesis' following the 'RĂ©union previous termdesnext termprevious termSciencesnext termprevious termdenext termprevious termlaprevious termTerre' 2010 conference held in Bordeaux, France. Further, based on the example of the Western Alps-Mediterranean domain we emphasize the possibility to integrate long and short term, plate- to sample-scale, datasets in order to constrain orogenic evolution
Utility of Quantitative 99mTc-MAA SPECT/CT for 90yttrium-Labelled Microsphere Treatment Planning: Calculating Vascularized Hepatic Volume and Dosimetric Approach
Objectives. The
aim of this study was to assess the
effectiveness of SPECT/CT for volume
measurements and to report a case illustrating
the major impact of SPECT/CT in calculating the
vascularized liver volume and dosimetry prior to
injecting radiolabelled yttrium-90 microspheres
(Therasphere). Materials and
Methods. This was a phantom study,
involving volume measurements carried out by two
operators using SPECT and SPECT/CT images. The
percentage of error for each method was
calculated, and interobserver reproducibility
was evaluated. A treatment using
Therasphere was planned in a patient
with three hepatic arteries, and the
quantitative analysis of SPECT/CT for this
patient is provided. Results.
SPECT/CT volume measurements proved to be
accurate (mean error <6% for volumes
â„16âcm3) and
reproductive (interobserver agreement = 0.9). In the case report, 99mTc-MAA SPECT/CT identified a large liver volume, not
previously identified with angiography, which was shown to be
vascularized after selective MAA injection into an arterial
branch, resulting in a large modification in the activity of
Therasphere used. Conclusions. MAA
SPECT/CT is accurate for vascularized liver volume measurements,
providing a valuable contribution to the therapeutic planning of
patients with complex hepatic vascularization
Influence of dissolution/reprecipitation reactions on metamorphic greenschist to amphibolite-facies mica <sup>40</sup>Ar/<sup>39</sup>Ar ages in the Longmen Shan (eastern Tibet)
Linking ages to metamorphic stages in rocks that have experienced low to mediumâgrade metamorphism can be particularly tricky due to the rarity of index minerals and the preservation of mineral or compositional relicts. The timing of metamorphism and the Mesozoic exhumation of the metasedimentary units and crystalline basement that form the internal part of the Longmen Shan (eastern Tibet, Sichuan, China), is, for these reasons, still largely unconstrained, but crucial for understanding the regional tectonic evolution of the eastern Tibet. Inâsitu coreârim 40Ar/39Ar biotite and UâTh/Pb allanite data show that amphiboliteâfacies conditions (~10â11 kbar, 530 °C to 6â7 kbar, 580 °C) were reached at 210â180 Ma and that biotite records crystallization, rather than cooling, ages. These conditions are mainly recorded in the metasedimentary cover. The 40Ar/39Ar ages obtained from matrix muscovite that partially reâequilibrated during the post peakâP metamorphic history comprise a mixture of ages between that of early prograde muscovite relicts and the timing of late muscovite recrystallization at c. 140â120 Ma. This event marks a previously poorly documented greenschist facies metamorphic overprint. This latest stage is also recorded in the crystalline basement, and defines the timing of the greenschistâoverprint (7 ± 1 kbar, 370 ± 35 °C). Numerical models of Ar diffusion show that the difference between 40Ar/39Ar biotite and muscovite ages cannot be explained by a slow and protracted cooling in an open system. The model and petrological results rather suggest that biotite and muscovite experienced different Ar retention and resetting histories. The Ar record in mica of the studied low to medium grade rocks seems to be mainly controlled by dissolutionâreprecipitation processes rather than by diffusive loss, and by different microstructural positions in the sample. Together, our data show that the metasedimentary cover was thickened and cooled independently from the basement prior to c. 140 Ma (with a relatively fast cooling at 4.5 ± 0.5 °C/Ma between 185 and 140 Ma). Since the Lower Cretaceous the metasedimentary cover and the crystalline basement experienced a coherent history during which both were partially exhumed. The Mesozoic history of the Eastern border of the Tibetan plateau is therefore complex, polyphase, and the basement was actively involved at least since the Early Cretaceous, changing our perspective on the contribution of the Cenozoic geology
Effect of mobile telephones on sperm quality: A systematic review and meta-analysis.
types: REVIEWThis is an open access article that is freely available in ORE or from the publisher's web site. Please cite the published version.© 2014 The Authors. Published by Elsevier Ltd.Mobile phones are owned by most of the adult population worldwide. Radio-frequency electromagnetic radiation (RF-EMR) from these devices could potentially affect sperm development and function. Around 14% of couples in high- and middle-income countries have difficulty conceiving, and there are unexplained declines in semen quality reported in several countries. Given the ubiquity of mobile phone use, the potential role of this environmental exposure needs to be clarified. A systematic review was therefore conducted, followed by meta-analysis using random effects models, to determine whether exposure to RF-EMR emitted from mobile phones affects human sperm quality. Participants were from fertility clinic and research centres. The sperm quality outcome measures were motility, viability and concentration, which are the parameters most frequently used in clinical settings to assess fertility. We used ten studies in the meta-analysis, including 1492 samples. Exposure to mobile phones was associated with reduced sperm motility (mean difference -8.1% (95% CI -13.1, -3.2)) and viability (mean difference -9.1% (95% CI -18.4, 0.2)), but the effects on concentration were more equivocal. The results were consistent across experimental in vitro and observational in vivo studies. We conclude that pooled results from in vitro and in vivo studies suggest that mobile phone exposure negatively affects sperm quality. Further study is required to determine the full clinical implications for both sub-fertile men and the general population.Open Access funded by Natural Environment Research CouncilJessica
Elliott-Friend is supported by a Natural Environment Research Council
PhD scholarship NE/J500185/
Diel time-courses of leaf growth in monocot and dicot species: endogenous rhythms and temperature effects
Diel (24 h) leaf growth patterns were differently affected by temperature variations and the circadian clock in several plant species. In the monocotyledon Zea mays, leaf elongation rate closely followed changes in temperature. In the dicotyledons Nicotiana tabacum, Ricinus communis, and Flaveria bidentis, the effect of temperature regimes was less obvious and leaf growth exhibited a clear circadian oscillation.These differences were related neither to primary metabolism nor to altered carbohydrate availability for growth. The effect of endogenous rhythms on leaf growth was analysed under continuous light in Arabidopsis thaliana, Ricinus communis, Zea mays, and Oryza sativa. No rythmic growth was observed under continuous light in the two monocotyledons, while growth rhythmicity persisted in the two dicotyledons. Based on model simulations it is concluded that diel leaf growth patterns in mono- and dicotyledons result from the additive effects of both circadian-clock-controlled processes and responses to environmental changes such as temperature and evaporative demand. Apparently very distinct diel leaf growth behaviour of monocotyledons and dicotyledons can thus be explained by the different degrees to which diel temperature variations affect leaf growth in the two groups of species which, in turn, depends on the extent of the leaf growth control by internal clocks
Characterization of temperatureâsensitive mutants reveals a role for receptorâlike kinase SCRAMBLED/STRUBBELIG in coordinating cell proliferation and differentiation during Arabidopsis leaf development
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94480/1/tpj5109.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/94480/2/tpj5109_sm_FigS1-S8-TableS1.pd
Astrophysically Triggered Searches for Gravitational Waves: Status and Prospects
In gravitational-wave detection, special emphasis is put onto searches that
focus on cosmic events detected by other types of astrophysical observatories.
The astrophysical triggers, e.g. from gamma-ray and X-ray satellites, optical
telescopes and neutrino observatories, provide a trigger time for analyzing
gravitational wave data coincident with the event. In certain cases the
expected frequency range, source energetics, directional and progenitor
information is also available. Beyond allowing the recognition of gravitational
waveforms with amplitudes closer to the noise floor of the detector, these
triggered searches should also lead to rich science results even before the
onset of Advanced LIGO. In this paper we provide a broad review of LIGO's
astrophysically triggered searches and the sources they target
- âŠ