Modeling currents at satellite altitudes

A mathematical formalism for modeling the poloidal magnetic field and current density at satellite altitudes is presented

Does the geoid drift west?

In 1970 Hide and Malin noted a correlation of about 0.8 between the geoid and the geomagnetic potential at the Earth's surface when the latter is rotated eastward in longitude by about 160 degrees and the spherical harmonic expansions of both functions are truncated at degree 4. From a century of magnetic observatory data, Hide and Malin inferred an average magnetic westward drift rate of about 0.27 degrees/year. They attributed the magnetic-gravitational correlation to a core event at about 1350 A.D. which impressed the mantle's gravity pattern at long wavelengths onto the core motion and the resulting magnetic field. The impressed pattern was then carried westward 160 degrees by the nsuing magnetic westward drift. An alternative possibility is some sort of steady physical coupling between the magnetic and gravitational fields (perhaps migration of Hide's bumps on the core-mantle interface). This model predicts that the geoid will drift west at the magnetic rate. On a rigid earth, the resulting changes in sea level would be easily observed, but they could be masked by adjustment of the mantle if it has a shell with viscosity considerably less than 10 to the 21 poise. However, steady westward drift of the geoid also predicts secular changes in g, the local acceleration of gravity, at land stations. These changes are now ruled out by recent independent high-accuracy absolute measurements of g made by several workers at various locations in the Northern Hemisphere

Unofficial Development Assistance: A Dynamic Model of Charities' Donation Income

The empirical literature on the determinants of charities donation income, distinguishing the charitable cause, is small. We extend the literature in several ways. First, we focus on overseas development charities allowing us to give more consideration to the particular characteristics of this cause. Second, we look at the impact of macroeconomic change over a quarter century including changes in household income and in government spending on ODA, as well as 'charity level' variables that earlier authors have considered. Third, we use a general dynamic model and rigorous testing procedures to arrive at our specification. Using a newly assembled long panel of data, we find evidence of a strong, but diminishing fundraising effect. We find no evidence of crowding out by either grants made directly to charities or by changes in the public provision of development funding.overseas development, charitable giving

Gibrat’s law and legacy for non-profit organisations: a non-parametric analysis

Gibrat’s Law of proportional effect (i.e. growth is independent of initial size) has been tested for firms for several decades. In this paper I test Gibrat’s Law for charities in England and Wales through time. Using a data set based on the population of registered charities from 1998 to 2009, I am able to test the ‘ex ante’ hypothesis that Gibrat’s Law holds over the long run for a sample of charities as well as testing Gibrat’s Legacy (that Gibrat’s Law holds for large and mature organisations), the ‘ex post’ hypothesis. I use nonparametric local polynomial smoothing techniques which are more robust to the issues of autocorrelation, sample selection and truncation that make the conventional parametric approaches to testing Gibrat’s Law difficult in practice. Results suggest that the dynamic processes driving growth in the charitable sectors may differ from those driving the growth of firms. Unlike for-profit firms Gibrat’s Law is found to generally hold when controlling for selection both ‘ex ante’ and ‘ex post’. Results may be driven by the absence of a minimum efficient scale which charities must achieve to survive and the different funding profiles of charities

The scientific case for magnetic field satellites

To make full use of modern magnetic data and the paleomagnetic record, we must greatly improve our understanding of how the geodynamo system works. It is clearly nonlinear, probably chaotic, and its dimensionless parameters cannot yet be reproduced on a laboratory scale. It is accessible only to theory and to measurements made at and above the earth's surface. These measurements include essentially all geophysical types. Gravity and seismology give evidence for undulations in the core-mantle boundary (CMB) and for temperature variations in the lower mantle which can affect core convection and hence the dynamo. VLBI measurements of the variations in the Chandler wobble and length of day are affected by, among other things, the electromagnetic and mechanical transfer of angular momentum across the CMB. Finally, measurements of the vector magnetic field, its intensity, or its direction, give the most direct access to the core dynamo and the electrical conductivity of the lower mantle. The 120 gauss coefficients of degrees up to 10 probably come from the core, with only modest interference by mantle conductivity and crustal magnetization. By contrast, only three angular accelerations enter the problem of angular momentum transfer across the CMB. Satellite measurements of the vector magnetic field are uniquely able to provide the spatial coverage required for extrapolation to the CMB, and to isolate and measure certain magnetic signals which to the student of the geodynamo represent noise, but which are of great interest elsewhere in geophysics. Here, these claims are justified and the mission parameters likely to be scientifically most useful for observing the geodynamo system are described

Unofficial development assistance: A dynamic model of charities' donation income

The empirical literature on the determinants of charities donation income, distinguishing the charitable cause, is small. We extend the literature in several ways. First, we focus on overseas development charities allowing us to give more consideration to the particular characteristics of this cause. Second, we look at the impact of macroeconomic change over a quarter century including changes in household income and in government spending on ODA, as well as 'charity level' variables that earlier authors have considered. Third, we use a general dynamic model and rigorous testing procedures to arrive at our specification. Using a newly assembled long panel of data, we find evidence of a strong, but diminishing fundraising effect. We find no evidence of crowding out by either grants made directly to charities or by changes in the public provision of development funding

Is income redistribution a form of insurance, a public good or both?

This paper is an empirical study of redistributive preferences. Our interest is what motivates net contributors to support redistributive policies. Using instrumental variable estimation and exploiting a particularity of the Spanish labour market we estimate how workers’ declared preferences for unemployment benefits spending respond to changes in the local unemployment rate. We then decompose this response into the part explained by risk aversion, and thus demand for insurance, and the part explained by the public goods nature of redistribution. Our results suggest that the declared preferences of workers for unemployment benefits spending are driven by demand for insurance rather than any public goods component. We show how these results suggest that preferences for redistribution in the form of unemployment benefits are driven by Insurance considerations rather than by any public goods consideration

Report of the panel on geopotential fields: Magnetic field, section 9

The objective of the NASA Geodynamics program for magnetic field measurements is to study the physical state, processes and evolution of the Earth and its environment via interpretation of measurements of the near Earth magnetic field in conjunction with other geophysical data. The fields measured derive from sources in the core, the lithosphere, the ionosphere, and the magnetosphere. Panel recommendations include initiation of multi-decade long continuous scalar and vector measurements of the Earth's magnetic field by launching a five year satellite mission to measure the field to about 1 nT accuracy, improvement of our resolution of the lithographic component of the field by developing a low altitude satellite mission, and support of theoretical studies and continuing analysis of data to better understand the source physics and improve the modeling capabilities for different source regions