Jump conditions for pressure anisotropy and comparison with the Earth's bow shock

International audienceTaking into account the pressure anisotropy in the solar wind, we study the magnetic field and plasma parameters downstream of a fast shock, as functions of upstream parameters and downstream pressure anisotropy. In our theoretical approach, we model two cases: a) the perpendicular shock and b) the oblique shock. We use two threshold conditions of plasma instabilities as additional equations to bound the range of pressure anisotropy. The criterion of the mirror instability is used for pressure anisotropy p \perp /p\parrallel > 1. Analogously, the criterion of the fire-hose instability is taken into account for pressure anisotropy p \perp /p\parrallel < 1. We found that the variations of the parallel pressure, the parallel temperature, and the tangential component of the velocity are most sensitive to the pressure anisotropy downstream of the shock. Finally, we compare our theory with plasma and magnetic field parameters measured by the WIND spacecraft

Extreme geomagnetic disturbances due to shocks within CMEs

We report on features of solar wind-magnetosphere coupling elicited by shocks propagating through coronal mass ejections (CMEs) by analyzing the intense geomagnetic storm of 6 August 1998. During this event, the dynamic pressure enhancement at the shock combined with a simultaneous increase in the southward component of the magnetic field resulted in a large earthward retreat of Earth\u27s magnetopause, which remained close to geosynchronous orbit for more than 4 h. This occurred despite the fact that both shock and CME were weak and relatively slow. Another similar example of a weak shock inside a slow CME resulting in an intense geomagnetic storm is the 30 September 2012 event, which strongly depleted the outer radiation belt. We discuss the potential of shocks inside CMEs to cause large geomagnetic effects at Earth, including magnetopause shadowing

Die topische Therapie von Oralem Lichen Planus mit Hyaluronsäure : Eine prospektive randomisierte Placebo-kontrollierte Cross-Over-Studie

Problemstellung: Zurzeit sind die Möglichkeiten zur Behandlung von Oralem Lichen Planus (OLP) nur wenig effektiv. Die Therapieformen sind hauptsächlich symptomatisch und erzielen nicht immer eindeutig zufriedenstellende Ergebnisse. Ziel: Das Ziel dieser Studie war es, die Behandlungsmöglichkeiten von OLP zu erweitern bzw. zu verbessern. Dazu wurde Hyaluronsäure (HA) mit einem Placebo zur Therapie dieser Erkrankung verglichen. Materialien und Methoden: Bei der vorliegenden Studie handelt es sich um eine prospektive, randomisierte, Placebo-kontrollierte, doppelblinde Cross-Over-Untersuchung. Es wurde ein Vergleich zwischen HA-Gel (0,24%) und einem Placebo (Hydroxypropylcellulose-Gel) angestellt, indem an 14 Probanden Speichelproben sowie klinische Parameter nach jeweils sechswöchiger Anwendung von HA bzw. Placebo erhoben wurden. Folgende Parameter wurden untersucht: der klinische Index nach Thongprasom, die Schmerzstärke anhand einer visuellen Analogskala, der Gingivalindex nach Löe und Silness, der Plaqueindex nach Silness und Löe sowie der OHIP-G-Fragebogen. Weiters wurden Speichelproben gesammelt, womit die Speichelmenge, der pH-Wert des Speichels sowie die Konzentrationen von TNF-alpha, IL-1-alpha, IL-6 und IL-8 ermittelt wurden. Die hier vorliegende Diplomarbeit beschränkt sich auf die Auswertung der klinischen Parameter. Ergebnisse/Schlussfolgerung: Nach statistischer Auswertung der klinischen Parameter mittels t-Test für gepaarte Stichproben sowie Wilcoxon-Vorzeichen-Rang-Test bei verbundenen Stichproben konnte keine signifikante Besserung nach der Behandlung mit HA im Vergleich zur Placebo-Anwendung festgestellt werden. Dieses Ergebnis wird allerdings auch durch die geringe Fallzahl bedingt, nur 9 der 14 Probanden schlossen die Studie ab (Drop-out-Quote 36%). Demzufolge kann die Wirksamkeit der HA zur Behandlung von OLP weder bestätigt noch ausgeschlossen werden.Problem: So far, the known treatment methods for Oral Lichen Planus (OLP) are of little effectiveness. Therefore, the therapy forms in use mainly focus on symptomatic treatment and dont always lead to satisfactory results. Aim: Goal of this study was to improve the therapeutical options of this disease. In order to achieve that, hyaluronic acid (HA) was compared with a placebo. Materials and Methods: The present study is a prospective, randomized, placebo-controlled, double-blind cross-over study. A comparison was made between HA-gel (0.24%) and a placebo (hydroxypropylcellulose-gel) by collecting saliva samples and clinical parameters after six weeks of HA treatment and after six weeks of placebo treatment. The following parameters were investigated: clinical severity index according to Thongprasom, pain intensity using a visual analogue scale, gingival index according to Löe and Silness, plaque index according to Silness and Löe as well as the OHIP-G questionnaire. Additionally, saliva samples were collected to determine the amount of saliva, the pH of the saliva and the concentrations of TNF-alpha, IL-1-alpha, IL-6 and IL-8. The present paper is limited to the evaluation of the clinical parameters. Results/Conclusion: Statistical evaluation of the stated clinical parameters using t-test for paired samples as well as Wilcoxon signed-rank-test for paired samples showed no significant improvement after therapy with HA compared to the placebo treatment. Only 9 of the 14 subjects completed the study (drop-out rate 36%) which affects the reported results. To sum it up, the efficacy of HA for the treatment of OLP can neither be confirmed nor excluded.eingereicht von Marlene MühlbachlerParalleltitel laut Übersetzung der Verfasserin/des VerfassersMedizinische Universität Wien, Diplomarbeit, 201

Jump conditions for pressure anisotropy and comparison with the Earth's bow shock

Taking into account the pressure anisotropy in the solar wind, we study the magnetic field and plasma parameters downstream of a fast shock, as functions of upstream parameters and downstream pressure anisotropy. In our theoretical approach, we model two cases: a) the perpendicular shock and b) the oblique shock. We use two threshold conditions of plasma instabilities as additional equations to bound the range of pressure anisotropy. The criterion of the mirror instability is used for pressure anisotropy p perp /pparrallel > 1. Analogously, the criterion of the fire-hose instability is taken into account for pressure anisotropy p perp /pparrallel < 1. We found that the variations of the parallel pressure, the parallel temperature, and the tangential component of the velocity are most sensitive to the pressure anisotropy downstream of the shock. Finally, we compare our theory with plasma and magnetic field parameters measured by the WIND spacecraft

Tenuous solar winds: Insights on solar wind-magneto sphere interactions

During solar cycle 23 quasi-dropouts of the solar wind (density < 1 cm_3) were observed. These tenuous winds allow us to probe properties of the magnetosphere and its coupling to the solar wind which would otherwise be obscured by the effect of high density. We focus on five areas which provided new insights into the response of geospace to solar wind variations: (i) the magnetospheric magnetic cofiguration; (ii) the polar rain; (iii) dayside flux erosion; (iv) magnetosheath waves; and (v) ring current constants. We find: (i) the geostationary field had dipolar strength and was inclined by £ 5°  to the dipolar direction; (ii) The solar wind strahl, and consequently the polar rain, were intensified; (iii) The depression of the geostationary field (DBGS) due to dayside flux erosion could be measured and was related to IMF BZ by DBGS = 2:8 + 2:3 Bz (nT); (iv) Right-hand electromagnetic ion cyclotron waves were excited alone in the magnetosheath and were generated directly from the temperature anisotropy of the solar wind; (v) Ring and magnetopause currents decreased to asymptotic values of 5 nT and 3 nT, respectively, which are substantially smaller than quiet-time values obtained from statistics.Fil: Farrugia, C. J.. University of New Hampshire; Estados UnidosFil: Gratton, Fausto Tulio Livio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; ArgentinaFil: Jordanova, V. K.. Laboratorio Nacional de Los Álamos; Estados UnidosFil: Matsui, H.. University of New Hampshire; Estados UnidosFil: Muehlbachler, S.. Max-Planck Institut fuer Sonnensystemforschung; AlemaniaFil: Torbert, R.. University of New Hampshire; Estados UnidosFil: Ogilvie, K.. Goddard Space Flight Center; Estados UnidosFil: Singer, H. J.. Space Weather Prediction Center; Estados Unido