The origin of polarity asymmetries in the history of the geomagnetic field

The behavior of magnetohydrodynamic stationary modes in the presence of an imposed weak magnetic field originating separately from the dynamo is studied. A rare class of stationary states is found that exhibit high sensitivity to the presence of weak imposed fields. The amplitude of the difference between the total fields of opposite polarity is much larger than the amplitude of the imposed nondynamo fields. It is proposed that Earth's magnetic field operates in such a mode, highly sensitive to the presence of an ambient field. An argument is given to explain why the terrestrial dynamo should choose to operate in one of these rare states. Implications are discussed for the general mechanism of dynamo magnetic field equilibrium in planets

A Systematic Review of the Evidence for the Sustainability of Household Water Treatment Interventions

This systematic review assesses the quantity and quality of evidence for the sustainability of household water treatment (HWT) since the World Health Organization (WHO) recently endorsed HWT based on growing evidence of HWT's ability to improve microbial water quality, effectiveness at reducing diarrheal disease, cost-effectiveness, and rapid application and acceptance. A large portion of the world population still relies on unsafe sources of drinking water, but whether HWT can support scaling-up efforts and be considered sustainable, it remains to be seen. Ultimately this systematic review found limited evidence of a sustained uptake and usage of HWT interventions, and results from studies that found high levels of confirmed usage after one year must be considered alongside their methodological quality

Generation of a dynamo magnetic field in a protoplanetary accretion disk

A new computational technique is developed that allows realistic calculations of dynamo magnetic field generation in disk geometries corresponding to protoplanetary and protostellar accretion disks. The approach is of sufficient generality to allow, in the future, a wide class of accretion disk problems to be solved. Here, basic modes of a disk dynamo are calculated. Spatially localized oscillatory states are found to occur in Keplerain disks. A physical interpretation is given that argues that spatially localized fields of the type found in these calculations constitute the basic modes of a Keplerian disk dynamo

Magnetic flares in the protoplanetary nebula and the origin of meteorite chondrules

This study proposes and analyzes a model for the chondrule forming heating events based on magnetohydrodynamic flares in the corona of the protoplanetary nebula which precipitate energy in the form of energetic plasma along magnetic field lines down toward the face of the nebula. It is found that flare energy release rates sufficient to melt the prechondrular matter, leading to the formation of the chondrules, can occur in the tenuous corona of a protostellar disk. Energy release rates sufficient to achieve melting require that the ambient magnetic field strength be in the range that has been inferred separately from independent meteorite remanent magnetization studies

Judicial Incentives and Indeterminacy in Substantive Review of Administrative Decisions

In the Chevron and State Farm cases the Supreme Court announced what appeared to be controlling standards for substantive review of administrative decisions. Instead, the Chevron framework has broken down, and State Farm has been all but ignored by agencies and the courts, including the Supreme Court. This article accounts for this breakdown by analyzing the impact of judicial incentives on substantive review in administrative law

The Effect of the 1998 Master Settlement on Prenatal Smoking

The Master Settlement Agreement (MSA) between the major tobacco companies and 46 states created an abrupt 45 cent (21%) increase in cigarette prices in November, 1998. Earlier estimates of the elasticity of prenatal smoking implied that the price rise would reduce prenatal cigarette smoking by 7% to 21%. Using birth records on 10 million U.S. births between January 1996 and February 2000, we examined the change in smoking during pregnancy and conditional smoking intensity in response to the MSA. Overall, adjusting for secular trends in smoking, prenatal smoking declined much less than predicted in response to the MSA.

Development of advanced digital techniques for data acquisition processing and communication Interim scientific report

Design, video data characteristics, error control, and compression algorithms for Mars television mapping missio