Forward Exchange Market Unbiasedness: The Case of the Australian Dollar Since 1984

This paper implements a new statistical approach to robust regression with nonstationary time series. The methods are presently under theoretical development in other work, and are briefly exposited here. They allow us to perform regressions in levels with nonstationary time series data, they accommodate data distributions with heavy tails and they permit serial dependence and temporal heterogeneity of unknown form in the equation errors. With these features the methods are well suited to applications with frequently sampled exchange rate data, which generally display all of these empirical characteristics. Our application is to daily data on spot and forward exchange rates between the Australian and US dollars over the period 1984-1991 following the deregulation of the Australian foreign exchange market. We find big differences between the robust and the non-robust regression outcomes and in the associated statistical tests of the hypothesis that the forward rate is an unbiased predictor of the future spot rate. The robust regression tests reject the unbiasedness hypothesis but still give the forward rate an important role as a predictor of the future spot rate.

Neutrino Scattering in a Magnetic Field

Motivated by the evidence for a finite neutrino mass we examine anew the interaction of neutrinos in a magnetic field. We present the rate for radiative scattering for both massless and massive neutrinos in the standard model and give the corresponding numerical estimates. We also consider the effects arising from a possible neutrino magnetic moment.Comment: 10 pages, 3 figures; Acknowledgements added 05.07.200

Latitudinal patterns of amino acid cycling and plant N uptake among North American forest ecosystems

Thesis (Ph.D.) University of Alaska Fairbanks, 2008Interest in the role of organic nitrogen (N) to the N economy of forest ecosystems is gaining momentum as ecologists revise the traditional paradigm in N cycling to emphasize the importance of depolymerization of soil organic matter (SOM) in controlling the bioavailability of N in forest soils. Still, there has yet to be a coordinated effort aimed at developing general patterns for soil organic N cycling across ecosystems that vary in climate, SOM quality, plant taxa, or dominant mycorrhizal association: ectomycorrhizae (EM) vs. arbuscular mycorrhizae (AM). In this study, experimental additions of 13C15N-glycine and 15NH4+ were traced in situ through fine root and soil N pools for six North American forest ecosystems in an effort to define patterns of plant and microbial N utilization among divergent forest types. Recovery of 15N in extractable soil pools varied by N form, forest type, and sampling period. At all sites, immobilization by the soil microbial biomass represented the largest short-term (<24 h) biotic sink for NH4+ and amino acid-N, but differences in microbial turnover of the two N forms were linked to cross-ecosystem differences in SOM quality, particularly the availability of labile carbon (C). At the conclusion of the experiment, microbial N turnover had transferred the majority of immobilized 15N to non-extractable soil N pools. By comparison, fine root uptake of NH4+ and glycine-N was low (<10% total tracer recovery), but 15N enrichment of this pool was still increasing at the final sampling period. Since there was no significant loss of 15N tracer within the bulk soil after 14 days for any forest type except sugar maple, it suggests plants have the capacity to capitalize on multiple N turnover events and thus represent an important long-term sink for ecosystem N. Plants in all stands had some capacity to absorb glycine intact, but plant N preference again varied by forest type. Relative uptake of amino acid-N versus inorganic N was lowest in tulip poplar and highest in red pine and balsam poplar, while white oak, sugar maple, and white spruce stands were statistically near unity with respect to the two N forms. However, N uptake ratios were threefold higher in EM-dominated stands than in AM-dominated stands indicating mycorrhizal association in part mediated plant N preference. Thus, amino acids represent an important component of the N economies of a broad spectrum of forest ecosystems, but their relevance to plant nutrition likely varies as a function of microbial demand for C as well as N

A concept for reducing oceanic separation minima through the use of a TCAS-derived CDTI

A concept for using a cockpit display of traffic information (CDTI), as derived from a modified version of the Traffic Alert and Collision Avoidance System 2 (TCAS 2), to support reductions in air traffic separation minima for an oceanic track system is presented. The concept, and the TCAS modifications required to support it, are described. The feasibility of the concept is examined from a number of standpoints, including expected benefits, maximum alert rates, and possible transition strategies. Various implementation issues are analyzed. Pilot procedures are suggested for dealing with alert situations. Possible variations of the concept are also examined. Finally, recommendations are presented for other studies and simulation experiments which can be used to further verify the feasibility of the concept

Microwave remote sensing of soil moisture, volume 1

Multifrequency sensor data from NASA's C-130 aircraft were used to determine which of the all weather microwave sensors demonstrated the highest correlation to surface soil moisture over optimal bare soil conditions, and to develop and test techniques which use visible/infrared sensors to compensate for the vegetation effect in this sensor's response to soil moisture. The L-band passive microwave radiometer was found to be the most suitable single sensor system to estimate soil moisture over bare fields. The perpendicular vegetation index (PVI) as determined from the visible/infrared sensors was useful as a measure of the vegetation effect on the L-band radiometer response to soil moisture. A linear equation was developed to estimate percent field capacity as a function of L-band emissivity and the vegetation index. The prediction algorithm improves the estimation of moisture significantly over predictions from L-band emissivity alone

Development of visible/infrared/microwave agriculture classification and biomass estimation algorithms, volume 2

Agricultural crop classification models using two or more spectral regions (visible through microwave) were developed and tested and biomass was estimated by including microwave with visible and infrared data. The study was conducted at Guymon, Oklahoma and Dalhart, Texas utilizing aircraft multispectral data and ground truth soil moisture and biomass information. Results indicate that inclusion of C, L, and P band active microwave data from look angles greater than 35 deg from nadir with visible and infrared data improved crop discrimination and biomass estimates compared to results using only visible and infrared data. The active microwave frequencies were sensitive to different biomass levels. In addition, two indices, one using only active microwave data and the other using data from the middle and near infrared bands, were well correlated to total biomass

Absolute intensity of radiation emitted by uranium plasmas

The absolute intensity of radiation emitted by fissioning and nonfissioning uranium plasmas in the spectral range from 350 nm to 1000 nm was measured. The plasma was produced in a plasma-focus apparatus and the plasma properties are simular to those anticipated for plasma-core nuclear reactors. The results are expected to contribute to the establishment of design criteria for the development of plasma-core reactors

Multifrequency remote sensing of soil moisture

Multifrequency sensor data collected at Guymon, Oklahoma and Dalhart, Texas using NASA's C-130 aircraft were used to determine which of the all-weather microwave sensors demonstrated the highest correlation to surface soil moisture over optimal bare soil conditions, and to develop and test techniques which use visible/infrared sensors to compensate for the vegetation effect in this sensor's response to soil moisture. The L-band passive microwave radiometer was found to be the most suitable single sensor system to estimate soil moisture over bare fields. In comparison to other active and passive microwave sensors the L-band radiometer (1) was influenced least by ranges in surface roughness; (2) demonstrated the most sensitivity to soil moisture differences in terms of the range of return from the full range of soil moisture; and (3) was less sensitive to errors in measurement in relation to the range of sensor response. L-band emissivity related more strongly to soil moisture when moisture was expressed as percent of field capacity. The perpendicular vegetation index as determined from the visible/infrared sensors was useful as a measure of the vegetation effect on the L-band radiometer response to soil moisture