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Magnetosheath Reconnection Before Magnetopause Reconnection Driven by Interplanetary Tangential Discontinuity: A Three-Dimensional Global Hybrid Simulation With Oblique Interplanetary Magnetic Field
Get PDFTerrestrial dayside dynamics associated with a southward turning, oblique interplanetary magnetic field (IMF) carried by an interplanetary tangential discontinuity (TD) is investigated by performing a three-dimensional global-scale hybrid simulation systematically for cases in which the incoming solar wind TD possesses various magnetic field rotation angles Delta Phi = 90 degrees to 180 degrees and half widths w = 2d(i0) to w = 30d(i0) where d(i0), is the ion inertial length in the solar wind. Overall, the TD is compressed while being transmitted into the magnetosheath, with different compression processes downstream of the quasi-parallel (Q-parallel to) and quasi-perpendicular (Q-perpendicular to) shocks. It is found that magnetosheath reconnection may take place downstream of both the Q-parallel to and Q-perpendicular to shocks due to interaction of the directional TD with the bow shock and magnetopause, but the existence of magnetosheath reconnection depends on w and Delta Phi. Magnetosheath flux ropes are formed through three-dimensional patchy reconnection in the thinned current sheet, with a longer rope lengths under a larger Delta Phi. There exists a dawn-dusk asymmetry in the spatial extent of the flux ropes, which becomes more significant as Delta Phi decreases. When Delta Phi decreases to 90 degrees, no reconnection flux ropes are found. Magnetopause reconnection is initiated when the magnetic fluxes with a southward turning IMF (on the sunward side) reach the magnetopause, and the magnetopause flux ropes can be mixed with the magnetosheath ones. Our simulation demonstrates that the effects of a southward turning of the IMF may not be a simple field direction change that leads to reconnection only at the magnetopause.PublishedYe
The Impact of Drought and Vascular-Inhabiting Pathogen Invasion in Pinus taeda Health
Get PDFThe complex interaction of various biotic and abiotic factors may put the overall stand health of Pinus spp. at risk. A study was designed to determine the combined impact of drought and vascular-inhabiting fungi (Leptographium terebrantis and Grosmannia huntii) in Pinus taeda. Seedlings from two P. taeda families were planted and watering treatments, (i) normal watering, (ii) moderate drought, and (iii) severe drought, were applied. One month following the initiation of watering treatments, seedling stems were artificially inoculated with L. terebrantis and G. huntii. Drought and fungal interaction significantly affected lesion length/seedling height, occlusion length/seedling height, and seedling fine root biomass. Leptographium terebrantis was more pathogenic under moderate and severe drought than normal watering condition, whereas the pathogenicity of G. huntii remains unaltered. The susceptibility of the families to vascular-inhabiting fungi remained the same under different watering treatments. Drought and specific vascular-inhabiting fungi may negatively impact P. taeda stand health.Ye
Dependence of the multipole moments, static polarizabilities, and static hyperpolarizabilities of the hydrogen molecule on the H-H separation in the ground singlet state
Get PDFIn this work, we provide values for the quadrupole moment Theta, the hexadecapole moment Phi, the dipole polarizability alpha, the quadrupole polarizability C, the dipole-octopole polarizability E, the second dipole hyperpolarizability gamma, and the dipole-dipole-quadrupole hyperpolarizability B for the hydrogen molecule in the ground singlet state, evaluated by finite-field configuration interaction singles and doubles (CISD) and coupled-cluster singles and doubles (CCSD) methods for 26 different H-H separations r, ranging from 0.567 a.u. to 10.0 a.u. Results obtained with various large correlation-consistent basis sets are compared at the vibrationally averaged bond length r(0) in the ground state. Results over the full range of r values are presented at the CISD/d-aug-cc-pV6Z level for all of the independent components of the property tensors. In general, our values agree well with previous ab initio results of high accuracy for the ranges of H-H distances that have been treated in common. To our knowledge, for H-2 in the ground state, our results are the first to be reported in the literature for Phi for r > 7.0 a.u., gamma and B for r > 6.0 a.u., and C and E for any H-H separation outside a narrow range around the potential minimum. Quantum Monte Carlo values of Theta have been given previously for H-H distances out to 10.0 a.u., but the statistical error is relatively large for r > 7.0 a.u. At the larger r values in this work, alpha(xx) and alpha(zz) show the expected functional forms, to leading order in r(-1). As r increases further, Theta and Phi vanish, while alpha, gamma, and the components of B converge to twice the isolated-atom values. Components of C and E diverge as r increases. Vibrationally averaged values of the properties are reported for all of the bound states (vibrational quantum numbers upsilon = 0-14) with rotational quantum numbers J = 0-3. Published by AIP Publishing.PublishedYe
Politics a "Chilly" Environment for Undergraduate Women in Norway
Get PDFGender differences in academic performance and attitudes are widespread in male-stereotyped disciplines but rarely are studied in the social sciences. To assess the extent that gender influences the behavior of undergraduate women in political science, participation was analyzed in a large (N = 130) introductory comparative-politics class at the University of Bergena large public university in Norway. In the 2016 fall semester, observers documented classroom behaviors of men and women using a protocol that characterizes types of in-class participation. Findings showed that women participate less than expected given their observed numbers in the classroom. After the semester ended, we provided an opportunity for students to describe why they chose to participate and whether they felt that barriers existed in the classroom that prevented them from expressing their opinions. This article characterizes those responses and presents the first study to draw conclusions about the gendered educational experience in political science by integrating these qualitative and quantitative results.PublishedYe
Equatorial Evolution of the Fast Magnetosonic Mode in the Source Region: Observation-Simulation Comparison of the Preferential Propagation Direction
Get PDFRecent analysis of an event observed by the Van Allen Probes in the source region outside the plasmapause has shown that fast magnetosonic waves (also referred to as equatorial noise) propagate preferentially in the azimuthal direction, implying that wave amplification should occur during azimuthal propagation. To demonstrate this, we carry out 2-D particle-in-cell simulations of the fast magnetosonic mode at the dipole magnetic equator with the simulation box size, the magnetic field inhomogeneity, and the plasma parameters chosen from the same event recently analyzed. The self-consistently evolving electric and magnetic field fluctuations are characterized by spectral peaks at harmonics of the local proton cyclotron frequency. The azimuthal component of the electric field fluctuations is larger than the radial component, indicating wave propagation mainly along the azimuthal direction. Because the simulation box is within the source region, this also implies wave amplification mainly during azimuthal propagation. The excellent agreement between the wave polarization properties of the present simulations and the recently reported observations is clear evidence that the main wave amplification occurs during azimuthal propagation in the source region.Publishe
Radical Politics in the 1860s: The Writing of Felix Holt
No full textArticle from the George Eliot Review, digitized and hosted by the George Eliot Review Online.Publishe
Generation of rising-tone chorus in a two-dimensional mirror field by using the general curvilinear PIC code
Get PDFRecently, the generation of rising-tone chorus has been implemented with one-dimensional (1-D) particle-in-cell (PIC) simulations in an inhomogeneous background magnetic field, where both the propagation of waves and motion of electrons are simply forced to be parallel to the background magnetic field. In this paper, we have developed a two-dimensional (2-D) general curvilinear PIC simulation code and successfully reproduced rising-tone chorus waves excited from an anisotropic electron distribution in a 2-D mirror field. Our simulation results show that whistler waves are mainly generated around the magnetic equator and continuously gain growth during their propagation toward higher-latitude regions. The rising-tone chorus waves are observed off the magnetic equator, which propagate quasi-parallel to the background magnetic field with the wave normal angle smaller than 25 degrees. Due to the propagating effect, the wave normal angle of chorus waves is increasing during their propagation toward higher-latitude regions along an enough curved field line. The chirping rate of chorus waves is found to be larger along a field line with a smaller curvature.Publishe