Least Squares Adjustment of Satellite Observations for Simultaneous Directions or Ranges. Part 1 - Formulation of Equations

Least squares adjustment of satellite observations for simultaneous directions or range

Gamma-ray emission associated with Cluster-scale AGN Outbursts

Recent observations have revealed the existence of enormously energetic ~10^61 erg AGN outbursts in three relatively distant galaxy clusters. These outbursts have produced bubbles in the intra-cluster medium, apparently supported by pressure from relativistic particles and/or magnetic fields. Here we argue that if > GeV particles are responsible then these particles are very likely protons and nuclei, rather than electrons, and that the gamma-ray emission from these objects, arising from the interactions of these hadrons in the intra-cluster medium, may be marginally detectable with instruments such as GLAST and HESS.Comment: 8 pages, 4 figures, accepted by MNRA

Sea surface velocities from visible and infrared multispectral atmospheric mapping sensor imagery

High resolution (100 m), sequential Multispectral Atmospheric Mapping Sensor (MAMS) images were used in a study to calculate advective surface velocities using the Maximum Cross Correlation (MCC) technique. Radiance and brightness temperature gradient magnitude images were formed from visible (0.48 microns) and infrared (11.12 microns) image pairs, respectively, of Chandeleur Sound, which is a shallow body of water northeast of the Mississippi delta, at 145546 GMT and 170701 GMT on 30 Mar. 1989. The gradient magnitude images enhanced the surface water feature boundaries, and a lower cutoff on the gradient magnitudes calculated allowed the undesirable sunglare and backscatter gradients in the visible images, and the water vapor absorption gradients in the infrared images, to be reduced in strength. Requiring high (greater than 0.4) maximum cross correlation coefficients and spatial coherence of the vector field aided in the selection of an optimal template size of 10 x 10 pixels (first image) and search limit of 20 pixels (second image) to use in the MCC technique. Use of these optimum input parameters to the MCC algorithm, and high correlation and spatial coherence filtering of the resulting velocity field from the MCC calculation yielded a clustered velocity distribution over the visible and infrared gradient images. The velocity field calculated from the visible gradient image pair agreed well with a subjective analysis of the motion, but the velocity field from the infrared gradient image pair did not. This was attributed to the changing shapes of the gradient features, their nonuniqueness, and large displacements relative to the mean distance between them. These problems implied a lower repeat time for the imagery was needed in order to improve the velocity field derived from gradient imagery. Suggestions are given for optimizing the repeat time of sequential imagery when using the MCC method for motion studies. Applying the MCC method to the infrared brightness temperature imagery yielded a velocity field which did agree with the subjective analysis of the motion and that derived from the visible gradient imagery. Differences between the visible and infrared derived velocities were 14.9 cm/s in speed and 56.7 degrees in direction. Both of these velocity fields also agreed well with the motion expected from considerations of the ocean bottom topography and wind and tidal forcing in the study area during the 2.175 hour time interval

Lost in translation: a multi-level case study of the metamorphosis of meanings and action in public sector organisational innovation

This paper explores the early implementation of an organisational innovation in the UK National Health Service (NHS) - Treatment Centres (TCs) - designed to dramatically reduce waiting lists for elective care. The paper draws on case studies of eight TCs (each at varying stages of their development) and aims to explore how meanings about TCs are created and evolve, and how these meanings impact upon the development of the organisational innovation. Research on organisational meanings needs to take greater account of the fact that modern organisations like the NHS are complex multi-level phenomena, comprising layers of interlacing networks. To understand the pace, direction and impact of organisational innovation and change we need to study the interconnections between meanings across different organisational levels. The data presented in this paper show how the apparently simple, relatively unformed, concept of a TC framed by central government, is translated and transmuted by subsequent layers in the health service administration, and by players in local health economies and, ultimately in the TCs themselves, picking up new rationales, meanings, and significance as it goes. The developmental histories of TCs reveal a range of significant re-workings of macro policy with the result that there is considerable diversity and variation between local TC schemes. The picture is of important disconnections between meanings, that in many ways mirror Weick’s (1976) ‘loosely coupled systems’. The emergent meanings and the direction of micro-level development of TCs appear more strongly determined by interactions within the local TC environment, notably between what we identify as groups of ‘idealists’, ‘pragmatists’, ‘opportunists’ and ‘sceptics’ than by the framing (Goffman 1974) provided by macro and meso organisational levels. While this illustrates the limitations of top down and policy-driven attempts at change, and highlights the crucial importance of the front-line local ‘micro-systems’ (Donaldson & Mohr, 2000) in the overall scheme of implementing organisational innovations, the space or headroom provided by frames at the macro and meso levels can enable local change, albeit at variable speed and with uncertain outcomes

Effect of excited states and applied magnetic fields on the measured hole mobility in an organic semiconductor

Copyright 2010 by the American Physical Society. Article is available at

Sub-Kolmogorov-Scale Fluctuations in Fluid Turbulence

We relate the intermittent fluctuations of velocity gradients in turbulence to a whole range of local dissipation scales generalizing the picture of a single mean dissipation length. The statistical distribution of these local dissipation scales as a function of Reynolds number is determined in numerical simulations of forced homogeneous isotropic turbulence with a spectral resolution never applied before which exceeds the standard one by at least a factor of eight. The core of the scale distribution agrees well with a theoretical prediction. Increasing Reynolds number causes the generation of ever finer local dissipation scales. This is in line with a less steep decay of the large-wavenumber energy spectra in the dissipation range. The energy spectrum for the highest accessible Taylor microscale Reynolds number R_lambda=107 does not show a bottleneck.Comment: 8 pages, 5 figures (Figs. 1 and 3 in reduced quality

The general form of supersymmetric solutions of N=(1,0) U(1) and SU(2) gauged supergravities in six dimensions

We obtain necessary and sufficient conditions for a supersymmetric field configuration in the N=(1,0) U(1) or SU(2) gauged supergravities in six dimensions, and impose the field equations on this general ansatz. It is found that any supersymmetric solution is associated to an $SU(2)\ltimes \mathbb{R}^4$ structure. The structure is characterized by a null Killing vector which induces a natural 2+4 split of the six dimensional spacetime. A suitable combination of the field equations implies that the scalar curvature of the four dimensional Riemannian part, referred to as the base, obeys a second order differential equation. Bosonic fluxes introduce torsion terms that deform the $SU(2)\ltimes\mathbb{R}^4$ structure away from a covariantly constant one. The most general structure can be classified in terms of its intrinsic torsion. For a large class of solutions the gauge field strengths admit a simple geometrical interpretation: in the U(1) theory the base is K\"{a}hler, and the gauge field strength is the Ricci form; in the SU(2) theory, the gauge field strengths are identified with the curvatures of the left hand spin bundle of the base. We employ our general ansatz to construct new supersymmetric solutions; we show that the U(1) theory admits a symmetric Cahen-Wallach$_4\times S^2$ solution together with a compactifying pp-wave. The SU(2) theory admits a black string, whose near horizon limit is $AdS_3\times S_3$. We also obtain the Yang-Mills analogue of the Salam-Sezgin solution of the U(1) theory, namely $R^{1,2}\times S^3$, where the $S^3$ is supported by a sphaleron. Finally we obtain the additional constraints implied by enhanced supersymmetry, and discuss Penrose limits in the theories.Comment: 1+29 pages, late