Labor Productivity in Britain and America During the Nineteenth Century

A number of writers have recently questioned whether labor productivity or per capita incomes were ever higher in the United Kingdom than in the United States. We show that although the United States already had a substantial labor productivity lead in industry as early as 1840, especially in manufacturing, labor productivity was broadly equal in the two countries in agriculture, while the United Kingdom was ahead in services. Hence aggregate labor productivity was higher in the United Kingdom, particularly since the United States had a larger share of the labor force in low value-added agriculture. U.S. overtaking occurred decisively only during the 1890s, as labor productivity pulled ahead in services and the share of agricultural employment declined substantially. Labor force participation was lower in the United States, so that the United Kingdom's labor productivity advantage in the mid-nineteenth century translated into a larger per capita income lead.

Noncommutative scalar field minimally coupled to gravity

A model for noncommutative scalar fields coupled to gravity based on the generalization of the Moyal product is proposed. Solutions compatible with homogeneous and isotropic flat Robertson-Walker spaces to first non-trivial order in the perturbation of the star-product are presented. It is shown that in the context of a typical chaotic inflationary scenario, at least in the slow-roll regime, noncommutativity yields no observable effect.Comment: Talk presented at the Workshop on Quantum Gravity and Noncommutative Geometry, 20-23 July 2004, Universidade Lus\'ofona, Lisbon, Portugal. To appear at Int. J. Mod. Phys.

From integrated to expedient: an adaptive framework for river basin management in developing countries

Water resource management / River basin management / Water allocation / Case studies / Africa South of Sahara / Great Ruaha River Basin

The Physical Properties of LBGs at z>5: Outflows and the "pre-enrichment problem"

We discuss the properties of Lyman Break galaxies (LBGs) at z>5 as determined from disparate fields covering approximately 500 sq. arcmin. While the broad characteristics of the LBG population has been discussed extensively in the literature, such as luminosity functions and clustering amplitude, we focus on the detailed physical properties of the sources in this large survey (>100 with spectroscopic redshifts). Specifically, we discuss ensemble mass estimates, stellar mass surface densities, core phase space densities, star-formation intensities, characteristics of their stellar populations, etc as obtained from multi-wavelength data (rest-frame UV through optical) for a subsample of these galaxies. In particular, we focus on evidence that these galaxies drive vigorous outflows and speculate that this population may solve the so-called ``pre-enrichment problem''. The general picture that emerges from these studies is that these galaxies, observed about 1 Gyr after the Big Bang, have properties consistent with being the progenitors of the densest stellar systems in the local Universe -- the centers of old bulges and early type galaxies.Comment: 4 pages, to appear in "Pathways Through an Eclectic Universe", J. H. Knappen, T. J. Mahoney, and A. Vazedekis (Eds.), ASP Conf. Ser., 200

D-instantons probing D3-branes and the AdS/CFT correspondence

D-instantons are considered as a probe of coinciding $N$ D3-branes. They can feel an external metric via the commutator terms in their effective action. We show that when the D-instantons are separated from the D3-branes, the metric which is probed at the one loop level, {\it exactly} coincides with that of the BPS R-R 3-brane. Interesting connection of this result to the possible explanation of the AdS/CFT correspondence within IKKT M-atrix theory is discussed.Comment: 8pp., Latex. Minor changes, misprints are correcte

On the Radii of Extrasolar Giant Planets

We have computed evolutionary models for extrasolar planets which range in mass from 0.1 to 3.0 Jovian Masses, and which range in equilibrium temperature from 113 K to 2000 K. We present four sequences of models, designed to show the structural effects of a solid core and of internal heating due to the conversion of kinetic to thermal energy at pressures of tens of bars. The model planetary radii are intended for comparisons with radii derived from observations of transiting extrasolar planets. To provide such comparisons, we expect that of order 10 transiting planets with orbital periods less than 200 days can be detected around bright (V<10) main-sequence stars for which accurate, well-sampled radial velocity measurements can be readily accumulated. Through these observations, structural properties of the planets will be derivable, particularly for low-mass, high-temperature planets. Implications regarding the transiting companion to OGLE-TR-56 recently announced by Konacki et al. are discussed. With regard to the confirmed transiting planet, HD 209458b, we find, in accordance with other recent calculations, that models without internal heating predict a radius that is 35 percent smaller than the observed radius. We explore the possibility that HD 209458b owes its large size to dissipation of energy arising from ongoing tidal circularization of the orbit. We show that residual scatter in the current radial velocity data set for HD 209458b is consistent with the presence of an as-of-yet undetected second companion, and that further radial velocity monitoring of the star is indicated.Comment: 23 pages, 3 figures, accepted by Astrophysical Journa

Discovery of a 3.6-hr Eclipsing Luminous X-Ray Binary in the Galaxy NGC 4214

We report the discovery of an eclipsing X-ray binary with a 3.62-hr period within 24" of the center of the dwarf starburst galaxy NGC 4214. The orbital period places interesting constraints on the nature of the binary, and allows for a few very different interpretations. The most likely possibility is that the source lies within NGC 4214 and has an X-ray luminosity of up to 7 e38 ergs/s. In this case the binary may well be comprised of a naked He-burning donor star with a neutron-star accretor, though a stellar-mass black-hole accretor cannot be completely excluded. There is no obvious evidence for a strong stellar wind in the X-ray orbital light curve that would be expected from a massive He star; thus, the mass of the He star should be <3-4 solar masses. If correct, this would represent a new class of very luminous X-ray binary -- perhaps related to Cyg X-3. Other less likely possibilities include a conventional low-mass X-ray binary that somehow manages to produce such a high X-ray luminosity and is apparently persistent over an interval of years; or a foreground AM Her binary of much lower luminosity that fortuitously lies in the direction of NGC 4214. Any model for this system must accommodate the lack of an optical counterpart down to a limiting magnitude of 22.6 in the visible.Comment: 7 pages, ApJ accepted versio