Density and temperature of energetic electrons in the Earth's magnetotail derived from high-latitude GPS observations during the declining phase of the solar cycle

Single relativistic-Maxwellian fits are made to high-latitude GPS-satellite observations of energetic electrons for the period January 2006-November 2010; a constellation of 12 GPS space vehicles provides the observations. The derived fit parameters (for energies similar to 0.1-1.0 MeV), in combination with field-line mapping on the nightside of the magnetosphere, provide a survey of the energetic electron density and temperature distribution in the magnetotail between McIlwain L-values of L = 6 and L = 22. Analysis reveals the characteristics of the density-temperature distribution of energetic electrons and its variation as a function of solar wind speed and the Kp index. The density-temperature characteristics of the magnetotail energetic electrons are very similar to those found in the outer electron radiation belt as measured at geosynchronous orbit. The energetic electron density in the magnetotail is much greater during increased geomagnetic activity and during fast solar wind. The total electron density in the magnetotail is found to be strongly correlated with solar wind speed and is at least a factor of two greater for high-speed solar wind (V-SW = 500-1000 km s(-1)) compared to low-speed solar wind (V-SW = 100-400 km s(-1)). These results have important implications for understanding (a) how the solar wind may modulate entry into the magnetosphere during fast and slow solar wind, and (b) if the magnetotail is a source or a sink for the outer electron radiation belt

Electron loss rates from the outer radiation belt caused by the filling of the outer plasmasphere: The calm before the storm

Measurements from seven spacecraft in geosynchronous orbit are analyzed to determine the decay rate of the number density of the outer electron radiation belt prior to the onset of high-speed-stream-driven geomagnetic storms. Superposed-data analysis is used with a collection of 124 storms. When there is a calm before the storm, the electron number density decays exponentially before the storm with a 3.4-day e-folding time: beginning about 4 days before storm onset, the density decreases from ∼4 × 10−4 cm−3 to ∼1 × 10−4 cm−3. When there is not a calm before the storm, the number density decay is very small. The decay in the number density of radiation belt electrons is believed to be caused by pitch angle scattering of electrons into the atmospheric loss cone as the outer plasmasphere fills during the calms. This is confirmed by separately measuring the density decay rate for times when the outer plasmasphere is present or absent. While the radiation belt electron density decreases, the temperature of the electron radiation belt holds approximately constant, indicating that the electron precipitation occurs equally at all energies. Along with the number density decay, the pressure of the outer electron radiation belt decays, and the specific entropy increases. From the measured decay rates, the electron flux to the atmosphere is calculated, and that flux is 3 orders of magnitude less than thermal fluxes in the magnetosphere, indicating that the radiation belt pitch angle scattering is 3 orders weaker than strong diffusion. Energy fluxes into the atmosphere are calculated and found to be insufficient to produce visible airglow

Children in Immigrant Families - The U.S. and 50 States: Economic Need Beyond the Official Poverty Measure

Analyzes gaps between child poverty rates in immigrant families and native-born families based on two alternative measures that take into account the costs of housing, food, other basic necessities, transportation, taxes, child care, and early education

Children in Immigrant Families -- The U.S. and 50 States: National Origins, Language, and Early Education

Draws on new results of U.S. Census 2000 data to focus on children in immigrant families, highlighting the proportion, dispersion, national origins, language, and early education of children in newcomer families nationwide and in various states

The Relationships of Selected Factors to the Personal Adjustment of a South Dakota Rural-nonfarm Community\u27s Older Population

Declining health, loss of physical vigor and the increased probability of death are conditions to which the aged of all societies must adjust. In addition, many older citizens in American society must face unique problems including the termination of gainful employment; reduced income; isolation through death or removal of family, friends, peers; increased periods of indolence; and a decreasing standard of living. Moreover, later life with its attendant complex of problems now faces more people in this country than ever before. The problems of older citizens in American society have therefore become the focus of considerable public attention in recent years. Particularly in South Dakota do growing numbers of older citizens give cause for increasing concern with their problems. Within the state the concentration of older persons is decidedly in the rural-nonfarm classification. Thus it is that the present study focuses on the problems of adjustment confronting older citizens in the rural-nonfarm community of Dell Rapids, South Dakota. The central question which the study seeks to contribute toward answering can be stated as follows: “What are the relationships between such factors as health, isolation activities, economic circumstances, etc., and the personal adjustment of older citizens?

A density-temperature description of the outer electron radiation belt during geomagnetic storms

Bi-Maxwellian fits are made to energetic-electron flux measurements from seven satellites in geosynchronous orbit, yielding a number density (n) and temperature (T) description of the outer electron radiation belt. For 54.5 spacecraft years of measurements the median value of n is 3.7 × 10−4 cm−3, and the median value of T is 148 keV. General statistical properties of n, T, and the 1.1–1.5 MeV flux F are investigated, including local-time and solar-cycle dependencies. Using superposed-epoch analysis where the zero epoch is convection onset, the evolution of the outer electron radiation belt through high-speed-stream-driven storms is investigated. The number-density decay during the calm before the storm, relativistic-electron dropouts and recoveries, and the heating of the outer electron radiation belt during storms are analyzed. Using four different “triggers” (sudden storm commencement (SSC), southward interplanetary magnetic field (IMF) portions of coronal mass ejection (CME) sheaths, southward-IMF portions of magnetic clouds, and minimum Dst) a selection of CME-driven storms are analyzed with superposed-epoch techniques. For CME-driven storms, only a very modest density decay prior to storm onset is found. In addition, the compression of the outer electron radiation belt at the time of SSC is analyzed, the number-density increase and temperature decrease during storm main phase are characterized, and the increase in density and temperature during storm recovery phase is determined. During the different phases of storms, changes in the flux are sometimes in response to changes in the temperature, sometimes to changes in the number density, and sometimes to changes in both. Differences are found between the density-temperature and flux descriptions, and it is concluded that more information is available using the density-temperature description

Electroneutrality and Phase Behavior of Colloidal Suspensions

Several statistical mechanical theories predict that colloidal suspensions of highly charged macroions and monovalent microions can exhibit unusual thermodynamic phase behavior when strongly deionized. Density-functional, extended Debye-H\"uckel, and response theories, within mean-field and linearization approximations, predict a spinodal phase instability of charged colloids below a critical salt concentration. Poisson-Boltzmann cell model studies of suspensions in Donnan equilibrium with a salt reservoir demonstrate that effective interactions and osmotic pressures predicted by such theories can be sensitive to the choice of reference system, e.g., whether the microion density profiles are expanded about the average potential of the suspension or about the reservoir potential. By unifying Poisson-Boltzmann and response theories within a common perturbative framework, it is shown here that the choice of reference system is dictated by the constraint of global electroneutrality. On this basis, bulk suspensions are best modeled by density-dependent effective interactions derived from a closed reference system in which the counterions are confined to the same volume as the macroions. Linearized theories then predict bulk phase separation of deionized suspensions only when expanded about a physically consistent (closed) reference system. Lower-dimensional systems (e.g., monolayers, small clusters), depending on the strength of macroion-counterion correlations, may be governed instead by density-independent effective interactions tied to an open reference system with counterions dispersed throughout the reservoir, possibly explaining observed structural crossover in colloidal monolayers and anomalous metastability of colloidal crystallites.Comment: 12 pages, 5 figures. Discussion clarified, references adde