68 research outputs found
Modeling the Young Sun's Solar Wind and its Interaction with Earth's Paleomagnetosphere
We present a focused parameter study of solar wind - magnetosphere
interaction for the young Sun and Earth, Ga ago, that relies on
magnetohydrodynamic (MHD) simulations for both the solar wind and the
magnetosphere. By simulating the quiescent young Sun and its wind we are able
to propagate the MHD simulations up to Earth's magnetosphere and obtain a
physically realistic solar forcing of it. We assess how sensitive the young
solar wind is to changes in the coronal base density, sunspot placement and
magnetic field strength, dipole magnetic field strength and the Sun's rotation
period. From this analysis we obtain a range of plausible solar wind conditions
the paleomagnetosphere may have been subject to. Scaling relationships from the
literature suggest that a young Sun would have had a mass flux different from
the present Sun. We evaluate how the mass flux changes with the aforementioned
factors and determine the importance of this and several other key solar and
magnetospheric variables with respect to their impact on the
paleomagnetosphere. We vary the solar wind speed, density, interplanetary
magnetic field strength and orientation as well as Earth's dipole magnetic
field strength and tilt in a number of steady-state scenarios that are
representative of young Sun-Earth interaction. This study is done as a first
step of a more comprehensive effort towards understanding the implications of
Sun-Earth interaction for planetary atmospheric evolution.Comment: 16 pages, 7 figure
Stellar Coronal and Wind Models: Impact on Exoplanets
Surface magnetism is believed to be the main driver of coronal heating and
stellar wind acceleration. Coronae are believed to be formed by plasma confined
in closed magnetic coronal loops of the stars, with winds mainly originating in
open magnetic field line regions. In this Chapter, we review some basic
properties of stellar coronae and winds and present some existing models. In
the last part of this Chapter, we discuss the effects of coronal winds on
exoplanets.Comment: Chapter published in the "Handbook of Exoplanets", Editors in Chief:
Juan Antonio Belmonte and Hans Deeg, Section Editor: Nuccio Lanza. Springer
Reference Work
Long-lived magnetism from solidification-driven convection on the pallasite parent body.
Palaeomagnetic measurements of meteorites suggest that, shortly after the birth of the Solar System, the molten metallic cores of many small planetary bodies convected vigorously and were capable of generating magnetic fields. Convection on these bodies is currently thought to have been thermally driven, implying that magnetic activity would have been short-lived. Here we report a time-series palaeomagnetic record derived from nanomagnetic imaging of the Imilac and Esquel pallasite meteorites, a group of meteorites consisting of centimetre-sized metallic and silicate phases. We find a history of long-lived magnetic activity on the pallasite parent body, capturing the decay and eventual shutdown of the magnetic field as core solidification completed. We demonstrate that magnetic activity driven by progressive solidification of an inner core is consistent with our measured magnetic field characteristics and cooling rates. Solidification-driven convection was probably common among small body cores, and, in contrast to thermally driven convection, will have led to a relatively late (hundreds of millions of years after accretion), long-lasting, intense and widespread epoch of magnetic activity among these bodies in the early Solar System.The research leading to these
results has received funding from the European Research Council under the European Union's
Seventh Framework Programme (FP/2007-2013) / ERC Grant Agreement No. 320750, the
European Community's Seventh Framework Programme (FP7/2007-2013) under grant
agreement no. 312284, the Natural Environment Research Council, Fundación ARAID and the
Spanish MINECO MAT2011-23791.This is the accepted manuscript. The final version is available from Nature at http://www.nature.com/nature/journal/v517/n7535/full/nature14114.html
Head & neck optical diagnostics: vision of the future of surgery
Review paper and Proceedings of the Inaugural Meeting of the Head and Neck Optical Diagnostics Society (HNODS) on March 14th 2009 at University College London
The future of medical diagnostics: Review paper
While histopathology of excised tissue remains the gold standard for diagnosis, several new, non-invasive diagnostic techniques are being developed. They rely on physical and biochemical changes that precede and mirror malignant change within tissue. The basic principle involves simple optical techniques of tissue interrogation. Their accuracy, expressed as sensitivity and specificity, are reported in a number of studies suggests that they have a potential for cost effective, real-time, in situ diagnosis. We review the Third Scientific Meeting of the Head and Neck Optical Diagnostics Society held in Congress Innsbruck, Innsbruck, Austria on the 11th May 2011. For the first time the HNODS Annual Scientific Meeting was held in association with the International Photodynamic Association (IPA) and the European Platform for Photodynamic Medicine (EPPM). The aim was to enhance the interdisciplinary aspects of optical diagnostics and other photodynamic applications. The meeting included 2 sections: oral communication sessions running in parallel to the IPA programme and poster presentation sessions combined with the IPA and EPPM posters sessions. © 2011 Jerjes et al; licensee BioMed Central Ltd
Multi-trait analysis characterizes the genetics of thyroid function and identifies causal associations with clinical implications
To date only a fraction of the genetic footprint of thyroid function has been clarified. We report a genome-wide association study meta-analysis of thyroid function in up to 271,040 individuals of European ancestry, including reference range thyrotropin (TSH), free thyroxine (FT4), free and total triiodothyronine (T3), proxies for metabolism (T3/FT4 ratio) as well as dichotomized high and low TSH levels. We revealed 259 independent significant associations for TSH (61% novel), 85 for FT4 (67% novel), and 62 novel signals for the T3 related traits. The loci explained 14.1%, 6.0%, 9.5% and 1.1% of the total variation in TSH, FT4, total T3 and free T3 concentrations, respectively. Genetic correlations indicate that TSH associated loci reflect the thyroid function determined by free T3, whereas the FT4 associations represent the thyroid hormone metabolism. Polygenic risk score and Mendelian randomization analyses showed the effects of genetically determined variation in thyroid function on various clinical outcomes, including cardiovascular risk factors and diseases, autoimmune diseases, and cancer. In conclusion, our results improve the understanding of thyroid hormone physiology and highlight the pleiotropic effects of thyroid function on various diseases.</p
Multi-trait analysis characterizes the genetics of thyroid function and identifies causal associations with clinical implications
To date only a fraction of the genetic footprint of thyroid function has been clarified. We report a genome-wide association study meta-analysis of thyroid function in up to 271,040 individuals of European ancestry, including reference range thyrotropin (TSH), free thyroxine (FT4), free and total triiodothyronine (T3), proxies for metabolism (T3/FT4 ratio) as well as dichotomized high and low TSH levels. We revealed 259 independent significant associations for TSH (61% novel), 85 for FT4 (67% novel), and 62 novel signals for the T3 related traits. The loci explained 14.1%, 6.0%, 9.5% and 1.1% of the total variation in TSH, FT4, total T3 and free T3 concentrations, respectively. Genetic correlations indicate that TSH associated loci reflect the thyroid function determined by free T3, whereas the FT4 associations represent the thyroid hormone metabolism. Polygenic risk score and Mendelian randomization analyses showed the effects of genetically determined variation in thyroid function on various clinical outcomes, including cardiovascular risk factors and diseases, autoimmune diseases, and cancer. In conclusion, our results improve the understanding of thyroid hormone physiology and highlight the pleiotropic effects of thyroid function on various diseases.</p
Multi-trait analysis characterizes the genetics of thyroid function and identifies causal associations with clinical implications.
To date only a fraction of the genetic footprint of thyroid function has been clarified. We report a genome-wide association study meta-analysis of thyroid function in up to 271,040 individuals of European ancestry, including reference range thyrotropin (TSH), free thyroxine (FT4), free and total triiodothyronine (T3), proxies for metabolism (T3/FT4 ratio) as well as dichotomized high and low TSH levels. We revealed 259 independent significant associations for TSH (61% novel), 85 for FT4 (67% novel), and 62 novel signals for the T3 related traits. The loci explained 14.1%, 6.0%, 9.5% and 1.1% of the total variation in TSH, FT4, total T3 and free T3 concentrations, respectively. Genetic correlations indicate that TSH associated loci reflect the thyroid function determined by free T3, whereas the FT4 associations represent the thyroid hormone metabolism. Polygenic risk score and Mendelian randomization analyses showed the effects of genetically determined variation in thyroid function on various clinical outcomes, including cardiovascular risk factors and diseases, autoimmune diseases, and cancer. In conclusion, our results improve the understanding of thyroid hormone physiology and highlight the pleiotropic effects of thyroid function on various diseases
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