THEMIS observations and riometry: A data comparison with a view to proxy and prediction

A comparison has been made between radio absorption events observed by riometer at selected times of day and bursts of electrons observed in the midnight sector by THEMIS satellites. The correlation is found to be good for absorption in the noon and midnight sectors but poor around dawn and dusk. For noon and midnight the absorption can be estimated from the THEMIS electron flux to better than a factor of 2 in most cases. In the noon sector the absorption follows the THEMIS event by about 30 min on average (though with considerable variation from case to case), but by night the absorption precedes the electron flux by about 8 min on average. Thus, the flux at THEMIS can be predicted from the absorption in the night sector, the accuracy being better than a factor of 3 in most cases. The flux observed also depends on the location of the satellite, reducing with increasing distance down the tail. It is estimated that the source of the tail events observed in this study was at about 6Re, and comparisons are made with the established general pattern of the substorm in auroral absorption

Sequential and parallel local search for the time-constrained travelling salesman problem

Local search has proven to be an effective solution approach for the traveling salesman problem. We consider variants of the TSP in which each city is to be visited within one or more given time windows. The travel times are symmetric and satisfy the triangle inequality; therobjective is to minimize the tour duration. We develop efficient sequential and parallel algorithms for the verification of local optimality of a tour with respect to k-exchanges

Parallel local search for the time-constrained traveling salesman problem

In the time-constrained TSP, each city has to be visited within a given time interval. Such `time windows' often occur in practice. When practical vehicle routing problems are solved in an interactive setting, one needs algorithms for the time-constrained TSP that combine a low running time with a high solution quality. Local search seems a natural approach. It is not obvious, however, how local search for the TSP has to be implemented so as to handle time windows efficiently. This is particularly true when parallel computer architectures are available. We consider these questions

Resonant Enhancement of Electronic Raman Scattering

We present an exact solution for electronic Raman scattering in a single-band, strongly correlated material, including nonresonant, resonant and mixed contributions. Results are derived for the spinless Falicov-Kimball model, employing dynamical mean field theory; this system can be tuned through a Mott metal-insulator transition.Comment: 4 pages, 3 figures, contribution to the SNS'2004 conferenc

Plausibility functions and exact frequentist inference

In the frequentist program, inferential methods with exact control on error rates are a primary focus. The standard approach, however, is to rely on asymptotic approximations, which may not be suitable. This paper presents a general framework for the construction of exact frequentist procedures based on plausibility functions. It is shown that the plausibility function-based tests and confidence regions have the desired frequentist properties in finite samples---no large-sample justification needed. An extension of the proposed method is also given for problems involving nuisance parameters. Examples demonstrate that the plausibility function-based method is both exact and efficient in a wide variety of problems.Comment: 21 pages, 5 figures, 3 table

Observations by incoherent scatter radar of related D- and F-region structuring at very high latitude

Properties and associations of F- and D-region ionospheric structures during weak electron precipitation at very high latitude are investigated using the Longyearbyen incoherent scatter radar. The radio absorption deduced from the electron density observations revealed evidence of a persistent low-altitude absorption layer peaking at 80-85 km. Inversion of the electron density profile to give an estimate of the incoming energetic electron spectrum suggests that its source may be the solar wind. Strong similarities are seen between variations in the F and D regions which suggest that the electron flux reaching the D-region is being modulated in energy by the variations of electron density in the F-region

Spin Dynamics of Cavity Polaritons

We have studied polariton spin dynamics in a GaAs/AlGaAs microcavity by means of polarization- and time-resolved photoluminescence spectroscopy as a function of excitation density and normal mode splitting. The experiments reveal a novel behavior of the degree of polarization of the emission, namely the existence of a finite delay to reach its maximum value. We have also found that the stimulated emission of the lower polariton branch has a strong influence on spin dynamics: in an interval of $\sim$150 ps the polarization changes from +100% to negative values as high as -60%. This strong modulation of the polarization and its high speed may open new possibilities for spin-based devices.Comment: 4 pages, 3 eps figures, RevTeX, Physical Review B Rapid (submitted

3D seismic imaging of buried Younger Dryas mass movement flows: Lake Windermere, UK

Windermere is a glacially overdeepened lake located in the southeastern Lake District, UK. Using the threedimensional(3D) Chirp subbottom profiler, we image mass movement deposits related to the Younger Dryas(YD) within a decimetre-resolution 3D seismic volume, documenting their internal structure and interactionwith preexisting deposits in unprecedented detail. Three distinct flow events are identified and mappedthroughout the 3D survey area. Package structures and seismic attributes classify them as: a small (totalvolume of c. 1500 m3) debris flow containing deformed translated blocks; a large (inferred total volume ofc. 500,000 m3), homogeneous fine-grained mass flow deposit; and a debris flow (inferred total volume ofc. 60,000 m3) containing small (c. 8.0×2.0 m) deformed translated blocks. Geomorphological mapping oftheir distribution and interaction with preexisting sediments permit the reconstruction of a depositionalhistory for the stratigraphic units identified in the seismic volume.<br/