Magnetospheric and auroral processes

Progress was made on the following two projects within the semiannual period: (1) simulations of the magnetic storm of April 1988 using the Magnetospheric Specification Model; and (2) improvement of a user-oriented electric-field model

Particle precipitaion into the thermosphere (invited review)

A review of research on particle precipitation into the thermosphere is presented. Particle precipitation plays an important role in thermospheric dynamics, often being both the most important ionization source and the most important heat source, comparable to Joule heating rates in the auroral zones and typically exceeding solar ultraviolet as an ionization mechanism in the nightside auroral zones and winter polar caps. Rees (1963) has shown that, roughly speaking, one electron-ion pair is produced by each 35 eV of incident electron energy flux; thus, over half of the incident electron energy flux goes into heating rather than into ionization. Precipitating ions also can produce ionization, also requiring roughly 35 eV per pair; however, since ion energy fluxes are typically much weaker than electron fluxes, they have often been neglected. The particle precipitation into the thermosphere is both an important ionization source and an important heat source; since the globally integrated value can vary over more than a factor of ten, and the instantaneous local rate can vary over nearly three orders of magnitude global, maps of precipitation rates are extremely important for predicting thermospheric weather

Dynamics explorer data analysis

The project has shown unambiguously that auroral acceleration is caused by electric fields aligned parallel to the Earth's magnetic field. Evidence was shown of significant ion heating as ions are accelerated upwards in auroral electric fields. This heating is most likely caused by the two-stream instability. The fate of upward ion beams associated with auroral arcs is shown; they appear in the opposite hemisphere as dispersive ion precipitation events. Magnetic merging of the Interplanetary Magnetic Field occurs with both closed dayside magnetospheric field lines and open tail lobe field lines simultaneously nearly 30 percent of the time. The sunward flow in the dawnside plasma sheet is 20 percent smaller, on average, than in the duskside. The convection throat is displaced slightly more toward dawn for B sub y greater than 0 than for B sub y less than 0

Magnetic Properties of Linear Chain Systems: Metamagnetism of Single Crystal Co(pyridine)\u3csub\u3e2\u3c/sub\u3eCl\u3csub\u3e2\u3c/sub\u3e

The metamagnetic behavior of the low temperature properties of single crystal Co(pyridine)2Cl2 is discussed. At 1.25 K oriented single crystals exhibit a two‐step metamagnetic transition at applied fields ∼0.8 and 1.6 kG along the b‐axis, a single transition at ∼0.7 kG for applied fields along the a∗ axis, and a single transition at ∼4.2 kG for an applied field along the c axis. Just above the transition fields a moment of 2μB/Co atom is measured for B0 parallel to the a∗ axis or b axis, and 0.4μB/Co atom is measured for the B0 parallel to the c axis. A large field dependent moment is observed at high fields. Many features of this compound closely mirror the behavior of CoCl2⋅2H2O. However, the Co(pyridine)2Cl2 has a much smaller interchain exchange, so that many features can be examined at lower fields. The basic features are consistent with a six‐sublattice model for the ordered antiferromagnetic system. Measurements of magnetic moment versus temperature show that Co(pyridine)2Cl2 does not obey a Curie–Weiss law even at relatively high temperatures

Educational Research and Developing Countries; facts, figures and some conceptual approaches for analysing interactions between funding, products and users

SUMMARY Educational research in the development context (ERDC) is the product of various kinds of international interactions and negotiations. These provide a typology of such research: disciplinary, instrumental, action, and policy research. All these are characterised by particular patterns of information flow and are influenced by resource availability and power structures. Suggestions for reforming ERDC are put forward. RESUMEN Investigación en educación y países en desarrollo: hechos, cifras y algunos enfoques conceptuales para analizar las interacciones existentes entre financiamiento, resultados y usuarios La investigación educacional en el contexto del desarrollo es resultado de variadas interacciones y negociaciones internacionales, las que le proporcionan una tipología; disciplina, instrumental, acción y política. Todas estas categorías están caracterizadas por determinados flujos informativos e influenciadas por la disponibilidad de recursos y las estructuras de poder. Se formulan sugerencias para reformarla. SOMMAIRE La recherche sur l'éducation et les pays en voie de développement: faits, chiffres, et quelques approches conceptuelles pour l'analyse des interactions entre le financement, les produits et les utilisateurs La recherche sur l'éducation dans le contexte du développement (RECD) est le résultat de différentes sortes d'interactions et de négotiations internationales. Elles donnent une typologie d'une telle recherche: disciplinaire, instrumentale, action, et politique de recherche. Elles sont toutes caractérisées par des formes particulières de courant d'information et sont influencées par la disponibilité des ressources et les structures de compétence Des suggestions en vue de faire des réformes dans la RECD sont énoncées

MeV magnetosheath ions energized at the bow shock

A causal relationship between midlatitude magnetosheath energetic ions and bow shock magnetic geometry was previously established for ion energy up to 200 keV e−1 for the May 4, 1998, storm event. This study demonstrates that magnetosheath ions with energies above 200 keV up to 1 MeV simply extend the ion spectrum to form a power law tail. Results of cross-correlation analysis suggest that these ions also come directly from the quasi-parallel bow shock, not the magnetosphere. This is confirmed by a comparison of energetic ion fluxes simultaneously measured in the magnetosheath and at the quasi-parallel bow shock when both regions are likely connected by the magnetic field lines. We suggest that ions are accelerated at the quasi-parallel bow shock to energies as high as 1 MeV and subsequently transported into the magnetosheath during this event

Richard P. Feynman 1918-1988

Richard Feynman, simply put, was a genius. His quick wit and uncommon grasp of physics meant that any research area he encountered, he quickly mastered. Despite the fact that his own area of research was not geophysics, his life and work influenced almost all of us. Virtually every physics graduate student who started in the mid 60s or later was exposed to his Lectures on Physics, either by having them as a text for a course or by using them (as I did) to bone up for oral qualifying exams. Feynman diagrams appear in nearly every modern quantum mechanics textbook and are featured in his official Caltech portrait, which illustrates this article