Hydrogen peroxide as a natural tracer of mixing in surface layers     

Norman M. Scully  Warwick F. Vincent  David R.S. Lean  Sally MacIntyre 《Aquatic Sciences - Research Across Boundaries》1998,60(2):169-186

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Role of Helicity in the Formation of Intermediate Filaments     

Mackay  D. H.  Priest  E. R.  Gaizauskas  V.  van Ballegooijen  A. A. 《Solar physics》1998,180(1-2):299-312

In the last few years new observations have shown that solar filaments and filament channels have a surprising hemispheric pattern. To explain this pattern, a new theory for filament channel and filament formation is put forward. The theory describes the formation of a specific type of filament, namely the intermediate filament which forms either between active regions or at the boundary of an active region. It describes the formation in terms of the emergence of a sheared activity complex. The complex then interacts with remnant flux and, after convergence and flux cancellation, the filament forms in the channel. A key feature of the model is the net magnetic helicity of the complex. With the correct sign a filament channel can form, but with the opposite sign no filament channel forms after convergence. It is shown how the hemispheric pattern of helicity in emerging flux regions produces the observed hemispheric pattern for filaments.  相似文献   

Energy release in solar flares     

J. C. Brown  E. Correia  F. Fárník  H. Garcia  J. -C. Hénoux  T. N. La Rosa  M. E. Machado  H. Nakajima  E. R. Priest 《Solar physics》1994,153(1-2):19-31

Team 2 of the Ottawa FLARES 22 Workshop dealt with observational and theoretical aspects of the characteristics and processes of energy release in flares. Main results summarized in this article stress the global character of the flaring phenomenon in active regions, the importance of discontinuities in magnetic connectivity, the role of field-aligned currents in free energy storage, and the fragmentation of energy release in time and space.Report of Team 2, Flares 22 Workshop, Ottawa, May 25–28, 1993.  相似文献   

Preflare state     

D. M. Rust  T. Sakurai  V. Gaizauskas  A. Hofmann  S. M. Martin  E. R. Priest  J. Wang 《Solar physics》1994,153(1-2):1-17

Discussion on the preflare state held at the Ottawa Flares 22 Workshop focused on the interpretation of solar magnetograms and of H filament activity. Magnetograms from several observatories provided evidence of significant build up of electric currents in flaring regions. Images of X-ray emitting structures provided a clear example of magnetic relaxation in the course of a flare. Emerging and cancelling magnetic fields appear to be important for triggering flares and for the formation of filaments, which are associated with eruptive flares. Filaments may become unstable by the build up of electric current helicity. Examples of heliform eruptive filaments were presented at the Workshop. Theoretical models linking filaments and flares are briefly reviewed.Report of Team 1, Flares 22 Workshop, Ottawa, May 25–28, 1993  相似文献   

Slow-shock heating and the Kopp-Pneuman model for ‘post’-flare loops     

P. J. Cargill  E. R. Priest 《Solar physics》1982,76(2):357-375

The heating of post-flare loops in the Kopp-Pneuman (1976) model is here reconsidered. In that kinematic model the loops are heated by gas-dynamic shocks to at most 3–4 × 10⁶ K. However, in a full dynamic model they would be replaced by slow magnetohydrodynamic shocks, which may provide more heating due to the additional release of magnetic energy. It is shown from a local compressible analysis that such shock waves can account for the observed temperatures of 5 × 10⁶–10⁷ K and also for the observed upward loop speeds of 1–50 km s^-1. The above values are obtained when the ambient plasma beta is 0.01 and the shocks propagate at highly sub-Alfvénic velocities. However, if the velocity of shock propagation approaches the Alfvén speed, then temperatures of 10⁸ K are produced. This may explain the extremely high temperatures that have been observed with the Solar Maximum Mission, when it is realised that the post-flare loop phenomenon may well be occurring very early on in the flare.A full dynamic model would require a sophisticated numerical computation, and so a simple global analytic model is developed here instead. It is incompressible and includes a strong solar-wind inflow along the reconnecting field lines. As the upflow increases, the loops become more compressed and the Alfvén waves approach one another.  相似文献   

Analysis of nonlinear associations between prenatal methylmercury exposure from fish consumption and neurodevelopmental outcomes in the Seychelles Main Cohort at 17 years     

Li-Shan?HuangEmail authorView author&#;s OrcID profile  Deborah?A.?Cory-Slechta  Christopher?Cox  Sally?W.?Thurston  Conrad?F.?Shamlaye  Gene?E.?Watson  Edwin?van Wijngaarden  Grazyna?Zareba  J.?J.?Strain  Gary?J.?Myers  Philip?W.?Davidson 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(4):893-904

The Seychelles Child Development Study has been examining the relationship between prenatal methylmercury (MeHg) exposure from consuming fish during pregnancy and child development. This study re-analyzes seven outcomes in the 17 year Main Cohort data to determine if there are nonlinear or non-homogeneous (subgroup) associations that were not identified in the linear analysis. We adopted two statistical approaches. First, we carried out an additive nonlinear analysis assuming homogeneous prenatal MeHg-outcome relationships to explore overall associations. Second, we applied the regression tree to the Woodcock–Johnson Calculation subtest (it was significantly associated in earlier analyses) and identified 4 clusters based on covariates. Then we used additive models to assess the prenatal MeHg association in each of the four clusters for all seven outcomes. This approach assumes nonlinear associations in each cluster and non-homogeneous associations between clusters. The additive nonlinear analysis yielded prenatal MeHg curves similar to the linear analysis. For the regression tree analysis, the curves relating prenatal MeHg to outcomes between the 4 clusters differed and some crossed at higher prenatal MeHg levels, suggesting non-homogeneity in the upper range of exposure. Additionally, some of the curves suggested a possible non-linear relationship within the range of exposure we studied. This non-linear analysis supports the findings from the linear analysis. It shows little evidence to support an adverse association of prenatal MeHg exposure through maternal consumption of fish contaminated with natural background levels. However, the tree analysis suggests that the prenatal exposure/outcome relationship may not be homogeneous across all individuals and that some subpopulations may have an adverse association in the upper range of the exposures studied. More robust data in the higher levels of exposure in this cohort are needed to confirm this finding.  相似文献   

Boxgrove: A Middle Pleistocene Hominid site at Eartham Quarry,Boxgrove, West Sussex     

Sally McBrearty 《Geoarchaeology》2000,15(8):819-822

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Thermal equilibria of coronal magnetic loops with non-constant cross-sectional area     

C. D. C. Steele  E. R. Priest 《Solar physics》1991,132(2):293-306

Equations of thermal equilibrium along coronal loops are solved in the absence of gravity but where the cross-sectional area changes along the loop. The footpoint temperature is assumed to be 2 × 10⁴ K. Several fundamental types of solution are found, namely hot loops, cool loops, hot-cool loops (where the footpoints and summits are cool but the intermediate parts are hotter) and warm loops (cool along most of their lengths except the summits). On increasing the cross-sectional area the summit temperature generally increases slightly except for warm loops where no increase in temperature is recorded and hot-cool loops where a dramatic increase in summit temperature may occur. The cool and hot-cool loops may model elementary fibril structures within prominences.  相似文献   

Smithsonian Institution’s Global Volcanism Network     

Edward Venzke  Sally Kuhn Sennert  Richard Wunderman 《Bulletin of Volcanology》2008,70(5):653-654

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 32, no. 7, July 2007 (on the Internet at ). Edited by scientists at the Smithsonian, this bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.  相似文献   

Reports from the Smithsonian’s Global Volcanism Network,June 2008     

Edward Venzke  Sally Kuhn Sennert  Richard Wunderman 《Bulletin of Volcanology》2009,71(2):229-231

Information included in this summary is based on more detailed reports published in the Bulletin of the Global Volcanism Network, vol. 33, no. 6, June 2008 (on the Internet at ). Edited by scientists at the Smithsonian, this bulletin includes reports provided by a worldwide network of correspondents. The reports contain the names and contact information for all sources. Please note that these reports are preliminary and subject to change as events are studied in more detail. The Global Volcanism Program welcomes further reports of current volcanism, seismic unrest, monitoring data, and field observations.  相似文献