Magnetic torquing is attractive as a control principle on small satellites. The actuation principle is to use the interaction between the earth's magnetic eld and magnetic eld generated by a coil set in the satellite. This control principle is inherently nonlinear, and diicult to use because control torques can only be generated perpendicular to the geomagnetic eld vector. This has been a serio...

Dynamo theory is reviewed with particular emphasis on recent developments. There now seems to be a strong case for dynamo eeects that are driven by the magnetic eld itself. This is linked to recent interpretations of the observed stellar cycle periods which suggest that the ratio of cycle frequency to rotational frequency increases, up to some point, with stellar chromospheric activity. This ra...

Following a given classi®cation of geomagnetic activity, we obtained aa index values for the Maunder minimum (1645±1715). It is found that the recurrent and ̄uctuating activities were not appreciable and that the shock activity levels were very low. The aa index level was due almost entirely to the quiet days. Calculated average solar-wind velocities were 194.3 km s from 1657 to 1700 and 218.7 ...

We present an agglomeration of stellar polarization catalogs with results for 9286 stars. We have endeavored to eliminate errors, provide accurate (∼arcsecond) positions, sensibly weight multiple observations of the same star, and provide reasonable distances. This catalog is available by anonymous FTP as ascii file /pub/polcat/p14.out at vermi.berkeley.edu. This manuscript is also available at...

We present a semiclassical nonlinear eld equation for the connning eld in 2+1{dimensional U (1) lattice gauge theory (compact QED). The equation is derived directly from the underlying microscopic quantum Hamiltonian by means of truncation. Its nonlinearities express the dynamic creation of magnetic monopole currents leading to the connnement of the electric eld between two static electric char...

Methods of functional brain imaging have been used to identify brain structures which are active during internal simulation of movements (ISM). Between 1977 and 1993 it was consistently reported that the primary motor cortex (MI) is not active during ISM whereas other cortical areas, in particular the supplementary motor area (SMA) are active. ISM was assumed to be a situation of "internal prog...

The spectacular progress in the eld of ultracold quantum gases is intimately connected with the availability of sophisticated techniques for quantum-level control of internal states, motional states, and collisional interactions. Atom chips provide such control in compact, robust, and scalable setups, which makes them attractive for both applications and fundamental studies. In this thesis I re...

A system of three spin12 atoms allows the construction of a qubit in the subspace of total angular momentum j = 12 that is not a ected by any magnetic eld activity on the magnetic moments of the atoms, provided that all three atoms experience the same magnetic eld. If, however, there are stray elds of di erent direction or strength at the sites of the atoms, the qubit will slowly decohere. It i...

In many situations, it is diicult to measure strong currents directly, so the currents are measured by their magnetic elds (e.g., by sensors glued onto the cable surface). If we have only one cable, then it is easy to reconstruct the current from the magnetic eld. But in many real-life situations, there is a neighboring cable whose current is also unknown. Moreover, the cables are hanging freel...

We present a new model of the magnetic ­ eld at the core{mantle boundary for the interval 1590{1990. The model, called gufm1, is based on a massive new compilation of historical observations of the magnetic ­ eld. The greater part of the new dataset originates from unpublished observations taken by mariners engaged in merchant and naval shipping. Considerable attention is given to both correcti...