The border economy

The Texas border community has historically been the state's most disadvantaged area. However, the last decade has seen dramatic improvements in unemployment and other economic factors. This series of nine articles explores issues important to the region's economy—from job growth, wages and education to infrastructure demands, maquiladoras and illegal immigration.>Texas ; Employment (Economic theory) ; North American Free Trade Agreement

Transportation infrastructure and the border economy

Trade ; Imports ; Exports ; Employment (Economic theory) ; North American Free Trade Agreement

A demonstration of high precision GPS orbit determination for geodetic applications

High precision orbit determination of Global Positioning System (GPS) satellites is a key requirement for GPS-based precise geodetic measurements and precise low-earth orbiter tracking, currently under study at JPL. Different strategies for orbit determination have been explored at JPL with data from a 1985 GPS field experiment. The most successful strategy uses multi-day arcs for orbit determination and includes fine tuning of spacecraft solar pressure coefficients and station zenith tropospheric delays using the GPS data. Average rms orbit repeatability values for 5 of the GPS satellites are 1.0, 1.2, and 1.7 m in altitude, cross-track, and down-track componenets when two independent 5-day fits are compared. Orbit predictions up to 24 hours outside the multi-day arcs agree within 4 m of independent solutions obtained with well tracked satellites in the prediction interval. Baseline repeatability improves with multi-day as compared to single-day arc orbit solutions. When tropospheric delay fluctuations are modeled with process noise, significant additional improvement in baseline repeatability is achieved. For a 246-km baseline, with 6-day arc solutions for GPS orbits, baseline repeatability is 2 parts in 100 million (0.4-0.6 cm) for east, north, and length components and 8 parts in 100 million for the vertical component. For 1314 and 1509 km baselines with the same orbits, baseline repeatability is 2 parts in 100 million for the north components (2-3 cm) and 4 parts in 100 million or better for east, length, and vertical components

The Language Attitude of Border Peoples Insular Riau, West Kalimantan, East Kalimantan, North Sulawesi, and the Eastern Sunda Islands

This research aims at describing (1) the language use of border area societies (Insular Riau, West Kalimantan, East Kalimantan, North Sulawesi, and the Eastern Sunda Islands) in terms of local language (BD), Indonesian (BI), and foreign language (BA) in the domains of family, society, and occupation, (2) language activity of border area societies relating to news observation, language attention, and language constraints in mass media, (3) language attitude of border area societies towards BD, BI, and BA. The findings are as follows. First, within the family and society at large, BD is more frequently used than BI and BA. This shows that BD functions in non-formal situations. In the professional field, however, BI is more frequently used than BD. Second, people in border provinces widely observe mass media, whether printed or electronic. They also often pay attention to the language the mass media uses. Third, border societies have a positive attitude towards BD as is shown (agree/totally agree) by the answers to eight questions relating to BD. The language attitude of border societies towards BI is positive based on the answers (agree/totally agree) to seven questions concerning BI. This also means that BI is prestigious for border people, especially in formal communication. The language attitude of border societies towards BA is mixed. In as far as it is negative it implies a positive evaluation of BD and BI because people appreciate them as part of their local and national identities

Toric Border Bases

We extend the theory and the algorithms of Border Bases to systems of Laurent polynomial equations, defining "toric" roots. Instead of introducing new variables and new relations to saturate by the variable inverses, we propose a more efficient approach which works directly with the variables and their inverse. We show that the commutation relations and the inversion relations characterize toric border bases. We explicitly describe the first syzygy module associated to a toric border basis in terms of these relations. Finally, a new border basis algorithm for Laurent polynomials is described and a proof of its termination is given for zero-dimensional toric ideals

Computing Border Bases without using a Term Ordering

Border bases, a generalization of Groebner bases, have actively been researched during recent years due to their applicability to industrial problems. A. Kehrein and M. Kreuzer formulated the so called Border Basis Algorithm, an algorithm which allows the computation of border bases that relate to a degree compatible term ordering. In this paper we extend the original Border Basis Algorithm in such a way that also border bases that do not relate to any term ordering can be computed by it.Comment: 12 page

Spacecraft-spacecraft very long baseline interferometry. Part 1: Error modeling and observable accuracy

In Part 1 of this two-part article, an error budget is presented for Earth-based delta differential one-way range (delta DOR) measurements between two spacecraft. Such observations, made between a planetary orbiter (or lander) and another spacecraft approaching that planet, would provide a powerful target-relative angular tracking data type for approach navigation. Accuracies of better than 5 nrad should be possible for a pair of spacecraft with 8.4-GHz downlinks, incorporating 40-MHz DOR tone spacings, while accuracies approaching 1 nrad will be possible if the spacecraft incorporate 32-GHz downlinks with DOR tone spacing on the order of 250 MHz; these accuracies will be available for the last few weeks or months of planetary approach for typical Earth-Mars trajectories. Operational advantages of this data type are discussed, and ground system requirements needed to enable spacecraft-spacecraft delta DOR observations are outlined. This tracking technique could be demonstrated during the final approach phase of the Mars '94 mission, using Mars Observer as the in-orbit reference spacecraft, if the Russian spacecraft includes an 8.4-GHz downlink incorporating DOR tones. Part 2 of this article will present an analysis of predicted targeting accuracy for this scenario