On the primordial condensation and accretion environment and the remanent magnetization of meteorites

In the context of various models for the early evolution of a solar nebula, the possible roles assigned to ambient magnetic fields and the paleointensities required to establish the stable natural remanent magnetization observed in meteorites, are discussed. It is suggested that the record of paleofields present during condensation, growth, and accumulation of grains is likely to have been preserved as chemical or thermochemical remanence in unaltered meteoritic material. Fine particle theories appear adequate for treating meteoritic remanence, if models based on corresponding types of permanent magnet materials, e.g., powder ferrites for chondrites and diffusion hardened alloys for iron meteorites, are adopted

On the Eleven-Dimensional Origins of Polarized D0-branes

The worldvolume theory of a D0-brane contains a multiplet of fermions which can couple to background spacetime fields. This coupling implies that a D0-brane may possess multipole moments with respect to the various type IIA supergravity fields. Different such polarization states of the D0-brane will thus generate different long-range supergravity fields, and the corresponding semi-classical supergravity solutions will have different geometries. In this paper, we reconsider such solutions from an eleven-dimensional perspective. We thus begin by deriving the ``superpartners'' of the eleven-dimensional graviton. These superpartners are obtained by acting on the purely bosonic solution with broken supersymmetries and, in theory, one can obtain the full BPS supermultiplet of states. When we dimensionally reduce a polarized supergraviton along its direction of motion, we recover a metric which describes a polarized D0-brane. On the other hand, if we compactify along the retarded null direction we obtain the short distance, or ``near-horizon'', geometry of a polarized D0-brane, which is related to finite $N$ Matrix theory. The various dipole moments in this case can only be defined once the eleven-dimensional metric is ``regularized'' and, even then, they are formally infinite. We argue, however, that this is to be expected in such a non-asymptotically flat spacetime. Moreover, we find that the superpartners of the D0-brane, in this r \ra 0 limit, possess neither spin nor D2-brane dipole moments.Comment: 20 pages, LaTeX. More references added, and a correction made to the supercharge. Version to be published in JHE

Foreign Ownership and the Theory of Trade and Welfare

Some standard topics in the theory of international trade are reconsidered in this paper by distinguishing between national and aggregate income when fixed supplies of foreign inputs are present within the home country. Under conditions that would ensure a national welfare gain if\u27 foreign ownership were absent, international transfer, economic growth, or tariff policy might cause a national welfare loss in the presence of foreign ownership. The techniques developed could be applied to other domestic distinctions (such as those based on race, sex, age, or ethnicity) and to the theory of\u27 customs unions in a three-country world

On the covariance of the Dirac-Born-Infeld-Myers action

A covariant version of the non-abelian Dirac-Born-Infeld-Myers action is presented. The non-abelian degrees of freedom are incorporated by adjoining to the (bosonic) worldvolume of the brane a number of anticommuting fermionic directions corresponding to boundary fermions in the string picture. The proposed action treats these variables as classical but can be given a matrix interpretation if a suitable quantisation prescription is adopted. After gauge-fixing and quantisation of the fermions, the action is shown to be in agreement with the Myers action derived from T-duality. It is also shown that the requirement of covariance in the above sense leads to a modified WZ term which also agrees with the one proposed by Myers.Comment: 18 pages. Minor alterations to the text; references adde

Unemployment Effects of Trade with a Low-Wage Country: A Minimum-Wage Model with Sector-Specific Factors

Contrary to conventional wisdom, this paper shows that a high-wage economy can paradoxically reduce its level of aggregate unemployment by engaging in international trade with a low-wage country. We demonstrate this possibility after introducing a minimum wage into the basic specific-factor model (with immobile capital and mobile labor), even though the opposite result is known to arise in the longer-run framework of the standard Heckscher-Ohlin-Samuelson model (with both inputs mobile). Our result provides a cautionary note for public-policy discussions that promote trade barriers as a way to reduce unemployment

Primordial magnetic field and spectral distortion of cosmic background radiation

The role played by a primordial magnetic field during the pre-recombination epoch is analysed through the cyclotron radiation (due to the free electrons) it might produce in the primordial plasma. We discuss the constraint implied by the measurement or lack thereof COBE on this primordial field.Comment: to appear in International Journal of Mod. Phy