Buildup of the ring current during periodic loading‐unloading cycles in the magnetotail driven by steady southward interplanetary magnetic field

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95239/1/jgra18825.pd

Plasmasphere Modeling with Ring Current Heating

Coulomb collisions between ring current ions and the thermal plasma in the plasmasphere will heat the plasmaspheric electrons and ions. During a storm such heating would lead to significant changes in the temperature and density of the thermal plasma. This was modeled using a time- dependent, one-stream hydrodynamic model for plasmaspheric flows, in which the model flux tube is connected to the ionosphere. The model simultaneously solves the coupled continuity, momentum, and energy equations of a two-ion (H(+) and O(+) quasineutral, currentless plasma. Heating rates due to collisions with ring current ions were calculated along the field line using a kinetic ring current model. First, diurnally reproducible results were found assuming only photoelectron heating of the thermal electrons. Then results were found with heating of the H(+) ions by the ring current during the recovery phase of a magnetic storm

The ionospheric outflow feedback loop

AbstractFollowing a long period of observation and investigation beginning in the early 1970s, it has been firmly established that Earth׳s magnetosphere is defined as much by the geogenic plasma within it as by the geomagnetic field. This plasma is not confined to the ionosphere proper, defined as the region within a few density scale heights of the F-region plasma density peak. Rather, it fills the flux tubes on which it is created, and circulates throughout the magnetosphere in a pattern driven by solar wind plasma that becomes magnetically connected to the ionosphere by reconnection through the dayside magnetopause. Under certain solar wind conditions, plasma and field energy is stored in the magnetotail rather than being smoothly recirculated back to the dayside. Its release into the downstream solar wind is produced by magnetotail disconnection of stored plasma and fields both continuously and in the form of discrete plasmoids, with associated generation of energetic Earthward-moving bursty bulk flows and injection fronts. A new generation of global circulation models is showing us that outflowing ionospheric plasmas, especially O+, load the system in a different way than the resistive F-region load of currents dissipating energy in the plasma and atmospheric neutral gas. The extended ionospheric load is reactive to the primary dissipation, forming a time-delayed feedback loop within the system. That sets up or intensifies bursty transient behaviors that would be weaker or absent if the ionosphere did not “strike back” when stimulated. Understanding this response appears to be a necessary, if not sufficient, condition for us to gain accurate predictive capability for space weather. However, full predictive understanding of outflow and incorporation into global simulations requires a clear observational and theoretical identification of the causal mechanisms of the outflows. This remains elusive and requires a dedicated mission effort

Local Heating of Oxygen Ions in the Presence of Magnetosonic Waves: Possible Source for the Warm Plasma Cloak?

In the energy regime between the plasmasphere (a few eV) and the ring current (greater than 1 keV), there exists another magnetospheric particle population with energies from a few eV to a few keV, the origins of which are debated. Studies explore generation mechanisms for warm plasma energies in the inner magnetosphere through two observed phenomena: the warm plasma cloak and the oxygen torus. The relations between these two populations are unclear. Recent data reveal local heating of cold H+ and He+ ions to warm plasma energies by magnetosonic waves. In this study, we report first observations of thermal O+ heating by magnetosonic waves and link the heating to a possible formation mechanism for the warm plasma cloak. The O+ heating is observed by different plasmaspheric density profiles, including density channels. We observe that O+ heating always occurs with thermal H+ and He+ heating. We investigate the harmonic structure of the observed magnetosonic waves and find intense O+ heating is accompanied by discrete heavy ion gyroharmonics. We suggest that locally heated thermal ions to 100s eV by magnetosonic waves along the plasmapause could provide a possible mechanism for warm plasma cloak generation.Key PointsThermal oxygen perpendicular heating is observed in the presence of magnetosonic waves near plasmaspheric density structuresMagnetosonic waves associated with thermal oxygen heating exhibit heavy ion gyroharmonics, implying resonant interactionsLocally heated thermal ions to 100s eV by magnetosonic waves by plasmapause provide a possible mechanism for warm plasma cloak generationPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156193/2/jgra55712_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156193/1/jgra55712.pd

The Bipolar II depression questionnaire: A self-report tool for detecting Bipolar II depression

Bipolar II (BP-II) depression is often misdiagnosed as unipolar (UP) depression, resulting in suboptimal treatment. Tools for differentiating between these two types of depression are lacking. This study aimed to develop a simple, self-report screening instrument to help distinguish BP-II depression from UP depressive disorder. A prototype BP-II depression questionnaire (BPIIDQ-P) was constructed following a literature review, panel discussions and a field trial. Consecutively assessed patients with a diagnosis of depressive disorder or BP with depressive episodes completed the BPIIDQ-P at a psychiatric outpatient clinic in Hong Kong between October and December 2013. Data were analyzed using discriminant analysis and logistic regression. Of the 298 subjects recruited, 65 (21.8%) were males and 233 (78.2%) females. There were 112 (37.6%) subjects with BP depression [BP-I = 42 (14.1%), BP-II = 70 (23.5%)] and 182 (62.4%) with UP depression. Based on family history, age at onset, postpartum depression, episodic course, attacks of anxiety, hypersomnia, social phobia and agoraphobia, the 8-item BPIIDQ-8 was constructed. The BPIIDQ-8 differentiated subjects with BP-II from those with UP depression with a sensitivity/specificity of 0.75/0.63 for the whole sample and 0.77/0.72 for a female subgroup with a history of childbirth. The BPIIDQ-8 can differentiate BP-II from UP depression at the secondary care level with satisfactory to good reliability and validity. It has good potential as a screening tool for BP-II depression in primary care settings. Recall bias, the relatively small sample size, and the high proportion of females in the BP-II sample limit the generalization of the results

First autochthonous Dirofilaria immitis (Leidy, 1856) infection in a dog in Hungary

AbstractA 4 year-old, male Hungarian Vizsla dog which had never been abroad was referred with poor general condition, decrease in body weight, haematemesis and jaundice to the Central Clinic of Veterinary Science University, Budapest. After symptomatic treatment abdominal ultrasonography and diagnostic laparatomy were carried out. The dog was humanely euthanized two days later following owner's consent because of sudden worsening of clinical conditions. Two adult heartworms (Dirofilaria immitis) were found in the right ventricle partially coiling around the tricuspid valve. PCR on blood was positive for both D. immitis and Dirofilaria repens while only D. repens microfilariae were found by modified Knott's test and the serological test was negative for D. immitis antigens. This is the first, confirmed report of autochthonous canine heartworm infection in Hungary

Effects of Different Geomagnetic Storm Drivers on the Ring Current: CRCM Results

The storm-time magnetic disturbance at the Earth\u27s equator, as commonly measured by the Dst index, is induced by currents in the near-Earth magnetosphere. The ring current is generally considered the most important contributor, but other magnetospheric currents have also been found to have significant effects. Of the two main types of solar geomagnetic storm drivers, Coronal Mass Ejections (CMEs) tend to have a much greater impact on Dst than Corotating Interaction Regions (CIRs). Ring current models have been found to underestimate Dst, particularly during storms driven by CIRs. One possible explanation is that the models neglect to handle some aspect of ring current physics that is particularly important for CIRs. This study uses the Comprehensive Ring Current Model (CRCM) to estimate the ring current contribution to Dst for a selection of storms of various strengths and different drivers (CMEs and CIRs) that have solar wind parameters that fit a typical profile. The model boundary is set to 10 RE at the equator, encompassing the entire ring current region. The magnetic field is held fixed, based on average storm parameters, which limits our model results to the effects of convection and plasma sheet density at the model boundary. Our model results generally show good agreement with the size and timing of fluctuations in Dst, which indicates that convection and boundary conditions play an important role in shaping Dst. We also find excellent agreement with the magnitude of Dst for CME-driven storms. For CIR-drivenstorms, however, the magnitude at the peak of the storm frequently deviates from actual Dst. In general, we agree with the results of previous research that CIR-driven storms are more underpredicted. However, this study includes some weaker CIR-driven stormsfor which Dst is actually overpredicted. Overall, when examining the dependence of modeled Dst* on actual Dst* at storm peak, we find that there is a statistically significant difference between CME- and CIR-driven storms. We also find that approximately half of the total ring current energy lies beyond an L-value of 6.6. However, this figure could be overestimated due to the use of a static magnetic field, which limits radial transport. Key Points Modeled vs actual Dst at storm peak is significantly different for CMEs and CIRs Convection and plasma sheet density are important for ring current energization Model shows half of total ring current energy lies beyond an L-value of 6.6

Mathematical models for vulnerable plaques

A plaque is an accumulation and swelling in the artery walls and typically consists of cells, cell debris, lipids, calcium deposits and fibrous connective tissue. A person is likely to have many plaques inside his/her body even if they are healthy. However plaques may become "vulnerable", "high-risk" or "thrombosis-prone" if the person engages in a high-fat diet and does not exercise regularly. In this study group, we proposed two mathematical models to describe plaque growth and rupture. The first model is a mechanical one that approximately treats the plaque as an inflating elastic balloon. In this model, the pressure inside the core increases and then decreases suggesting that plaque stabilization and prevention of rupture is possible. The second model is a biochemical one that focuses on the role of MMPs in degrading the fibrous plaque cap. The cap stress, MMP concentration, plaque volume and cap thickness are coupled together in a system of phenomenological equations. The equations always predict an eventual rupture since the volume, stresses and MMP concentrations generally grow without bound. The main weakness of the model is that many of the important parameters that control the behavior of the plaque are unknown. The two simple models suggested by this group could serve as a springboard for more realistic theoretical studies. But most importantly, we hope they will motivate more experimental work to quantify some of the important mechanical and biochemical properties of vulnerable plaques