The Geometric Spreading of Coronal Plumes and Coronal Holes

The geometric spreading in plumes and in the interplume region in coronal holes is calculated, using analytic and numerical theoretical models, between 1.0 and 5.0 solar radius. We apply a two-scale approximation that permits the rapid local spreading at the base of plumes (f(sub t)) to be evaluated separately from the global spreading (f(sub g)) imposed by coronal hole geometry. We show that f(sub t) can be computed from a potential-field model and f(sub g) can be computed from global magnetohydrodynamic simulations of coronal structure. The approximations are valid when the plasma beta is mail with respect to unity and for a plume separation small with respect to a solar radius

Probing the Edge of the Solar System: Formation of an Unstable Jet-Sheet

The Voyager spacecraft is now approaching the edge of the solar system. Near the boundary between the solar system and the interstellar medium we find that an unstable ``jet-sheet'' forms. The jet-sheet oscillates up and down due to a velocity shear instability. This result is due to a novel application of a state-of-art 3D Magnetohydrodynamic (MHD) code with a highly refined grid. We assume as a first approximation that the solar magnetic and rotation axes are aligned. The effect of a tilt of the magnetic axis with respect to the rotation axis remains to be seen. We include in the model self-consistently magnetic field effects in the interaction between the solar and interstellar winds. Previous studies of this interaction had poorer spatial resolution and did not include the solar magnetic field. This instability can affect the entry of energetic particles into the solar system and the intermixing of solar and interstellar material. The same effect found here is predicted for the interaction of rotating magnetized stars possessing supersonic winds and moving with respect to the interstellar medium, such as O stars.Comment: 9 pages, 4 figures, accepted for publication in ApJ

Validation of a synoptic solar wind model

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94963/1/jgra19149.pd

The First Quiescent Galaxies in TNG300

We identify the first quiescent galaxies in TNG300, the largest volume of the IllustrisTNG cosmological simulation suite, and explore their quenching processes and time evolution to z=0. We find that the first quiescent galaxies with stellar masses M_* > 3 x 10^{10} M_sun and specific star formation rates sSFR < 10^{-11} yr^{-1} emerge at z~4.2 in TNG300. Suppression of star formation in these galaxies begins with a thermal mode of AGN feedback at z~6, and a kinetic feedback mode acts in each galaxy by z~4.7 to complete the quenching process, which occurs on a time-scale of ~0.35 Gyr. Surprisingly, we find that the majority of these galaxies are not the main progenitors of their z=0 descendants; instead, four of the five galaxies fall into more massive galaxies in subsequent mergers at a range of redshifts 2.5 < z < 0.2. By z=0, these descendants are the centres of galaxy clusters with average stellar masses of 8 x 10^{11} M_sun. We make predictions for the first quenched galaxies to be located by the James Webb Space Telescope (JWST).Comment: 6 pages, 4 figure

Isotopes in pyrogenic carbon: a review

Pyrogenic carbon (PC; also known as biochar, charcoal, black carbon and soot) derived from natural and anthropogenic burning plays a major, but poorly quantified, role in the global carbon cycle. Isotopes provide a fundamental fingerprint of the source of PC and a powerful tracer of interactions between PC and the environment. Radiocarbon and stable carbon isotope techniques have been widely applied to studies of PC in aerosols, soils, sediments and archaeological sequences, with the use of other isotopes currently less developed. This paper reviews the current state of knowledge regarding (i) techniques for isolating PC for isotope analysis and (ii) processes controlling the carbon (&lt;sup&gt;13&lt;/sup&gt;C and &lt;sup&gt;14&lt;/sup&gt;C), nitrogen, oxygen, hydrogen and sulfur isotope composition of PC during formation and after deposition. It also reviews the current and potential future applications of isotope based studies to better understand the role of PC in the modern environment and to the development of records of past environmental change

Abundances of the elements in the solar system

A review of the abundances and condensation temperatures of the elements and their nuclides in the solar nebula and in chondritic meteorites. Abundances of the elements in some neighboring stars are also discussed.Comment: 42 pages, 11 tables, 8 figures, chapter, In Landolt- B\"ornstein, New Series, Vol. VI/4B, Chap. 4.4, J.E. Tr\"umper (ed.), Berlin, Heidelberg, New York: Springer-Verlag, p. 560-63

The European multicenter trial on the safety and efficacy of guided oblique lumbar interbody fusion (GO-LIF)

Background: Because of the implant-related problems with pedicle screw-based spinal instrumentations, other types of fixation have been tried in spinal arthrodesis. One such technique is the direct trans-pedicular, trans-discal screw fixation, pioneered by Grob for spondylolisthesis. The newly developed GO-LIF procedure expands the scope of the Grob technique in several important ways and adds security by means of robotic-assisted navigation. This is the first clinical trial on the GO-LIF procedure and it will assess safety and efficacy. Methods/Design: Multicentric prospective study with n = 40 patients to undergo single level instrumented spinal arthrodesis of the lumbar or the lumbosacral spine, based on a diagnosis of: painful disc degeneration, painful erosive osteochondrosis, segmental instability, recurrent disc herniation, spinal canal stenosis or foraminal stenosis. The primary target criteria with regards to safety are: The number, severity and cause of intra-and perioperative complications. The number of significant penetrations of the cortical layer of the vertebral body by the implant as recognized on postoperative CT. The primary target parameters with regards to feasibility are: Performance of the procedure according to the preoperative plan. The planned follow-up is 12 months and the following scores will be evaluated as secondary target parameters with regards to clinical improvement: VAS back pain, VAS leg pain, Oswestry Disability Index, short form - 12 health questionnaire and the Swiss spinal stenosis questionnaire for patients with spinal claudication. The secondary parameters with regards to construct stability are visible fusion or lack thereof and signs of implant loosening, implant migration or pseudarthrosis on plain and functional radiographs. Discussion: This trial will for the first time assess the safety and efficacy of guided oblique lumbar interbody fusion. There is no control group, but the results, the outcome and the rate of any complications will be analyzed on the background of the literature on instrumented spinal fusion. Despite its limitations, we expect that this study will serve as the key step in deciding whether a direct comparative trial with another fusion technique is warranted

Guidelines for the labelling of leucocytes with 99mTc-HMPAO

We describe here a protocol for labelling autologous white blood cells with 99mTc-HMPAO based on previously published consensus papers and guidelines. This protocol includes quality control and safety procedures and is in accordance with current European Union regulations and International Atomic Energy Agency recommendations

Origins of the Ambient Solar Wind: Implications for Space Weather

The Sun's outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal heating and the acceleration of the ambient solar wind. We also discuss where the community stands in its ability to forecast how variations in the solar wind (i.e., fast and slow wind streams) impact the Earth. Although the last few decades have seen significant progress in observations and modeling, we still do not have a complete understanding of the relevant physical processes, nor do we have a quantitatively precise census of which coronal structures contribute to specific types of solar wind. Fast streams are known to be connected to the central regions of large coronal holes. Slow streams, however, appear to come from a wide range of sources, including streamers, pseudostreamers, coronal loops, active regions, and coronal hole boundaries. Complicating our understanding even more is the fact that processes such as turbulence, stream-stream interactions, and Coulomb collisions can make it difficult to unambiguously map a parcel measured at 1 AU back down to its coronal source. We also review recent progress -- in theoretical modeling, observational data analysis, and forecasting techniques that sit at the interface between data and theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue connected with a 2016 ISSI workshop on "The Scientific Foundations of Space Weather." 44 pages, 9 figure