The "Information Highway" and the Location of Economic Activity

This paper studies possible consequences from building an "information highway" for the location of firms and households in the context of a two-region, three-good model of economic geography. The advancements in information and communication technology are identified with a decrease in transportation costs for intermediate services on the one hand and with a decrease in the costs of teleworking for households on the other hand. The stability of three situations is investigated: all production in the city; manufacturing in the city and services in the rural region; manufacturing in the rural region and services in the city (service city). While the first situation can constitute a stable equilibrium, the second cannot and the third is only feasible if additional locational externalities exist for services in the city. Even then the service city can become a "virtual city" if costs of teleworking decrease enough to encourage households to move to the rural region and telework.cities, location of firms, telecommunications, information highway

Study of multiple cycles valves

A discussion is presented regarding valves which can be cycled repeatedly and are available from industry for application in the inlet system for the Pioneer Venus Probe mass spectrometer. Both solenoid type and latching type valves are considered. The study is divided into two principal areas: (1) preparation of a valve specification reflecting the requirements of the inlet system cyclic valves for the Pioneer Venus Probe mass spectrometer and the submittal of this specification to potential valve suppliers for their response and proposal; (2) preparation of a design layout of an optimum cyclic valve meeting all of the valve specification requirements

Food Consumption and Growth in a Two Sector Economy - A Theoretical Model and Numerical Simulations

I discuss the dynamics of growth and structural change in a two- sector dual economy characterized by a positive relationship between nutrition and productivity. A rise in agricultural production increases food consumption as well as labor productivity. The different outcomes are discussed when the level of food consumption increases productivity either in agriculture or in industry (static effect) or when it influence the productivity of learning by doing (dynamic effect).growth and development theory, nutrition, efficiency wages, numerical simulations

A Long-Lived Accretion Disk Around a Lithium-Depleted Binary T Tauri Star

We present a high dispersion optical spectrum of St 34 and identify the system as a spectroscopic binary with components of similar luminosity and temperature (both M3+/-0.5). Based on kinematics, signatures of accretion, and location on an H-R diagram, we conclude that St 34 is a classical T Tauri star belonging to the Taurus-Auriga T Association. Surprisingly, however, neither component of the binary shows LiI 6708 A, absorption, the most universally accepted criterion for establishing stellar youth. In this uniquely known instance, the accretion disk appears to have survived longer than the lithium depletion timescale. We speculate that the long-lived accretion disk is a consequence of the sub-AU separation companion tidally inhibiting, though not preventing, circumstellar accretion. Comparisons with pre-main sequence evolutionary models imply, for each component of St 34, a mass of 0.37+/-0.08 Msun and an isochronal age of 8+/-3 Myr, which is much younger than the predicted lithium depletion timescale of ~ 25 Myr. Although a distance 38% closer than that of Taurus-Auriga or a hotter temperature scale could reconcile this discrepancy at 21-25 Myr, similar discrepancies in other systems and the implications of an extremely old accreting Taurus-Auriga member suggest instead a possible problem with evolutionary models. Regardless, the older age implied by St 34's depleted lithium abundance is the first compelling evidence for a substantial age spread in this region. Additionally, since St 34's coeval co-members with early M spectral types would likewise fail the lithium test for youth, current membership lists may be incomplete.Comment: 4 pages, including 2 figures. Accepted for publication in ApJ Let

Birth, survival and death of languages by Monte Carlo simulation

Simulations of physicists for the competition between adult languages since 2003 are reviewed. How many languages are spoken by how many people? How many languages are contained in various language families? How do language similarities decay with geographical distance, and what effects do natural boundaries have? New simulations of bilinguality are given in an appendix.Comment: 24 pages review, draft for Comm.Comput.Phys., plus appendix on bilingualit