Enhancing weak transient signals in SEVIRI false color imagery: application to dust source detection in southern Africa

A method is described to significantly enhance the signature of dust events using observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI). The approach involves the derivation of a composite clear-sky signal for selected channels on an individual time step and pixel basis. These composite signals are subtracted from each observation in the relevant channels to enhance weak transient signals associated with either (a) low levels of dust emission or (b) dust emissions with high salt or low quartz content. Different channel combinations, of the differenced data from the steps above, are then rendered in false color imagery for the purpose of improved identification of dust source locations and activity. We have applied this clear-sky difference (CSD) algorithm over three (globally significant) source regions in southern Africa: the Makgadikgadi Basin, Etosha Pan, and the Namibian and western South African coast. Case study analyses indicate three notable advantages associated with the CSD approach over established image rendering methods: (i) an improved ability to detect dust plumes, (ii) the observation of source activation earlier in the diurnal cycle, and (iii) an improved ability to resolve and pinpoint dust plume source locations

Soil bulk density sampling for neutron gauge calibration

The ASCE Task Committee on Neutron Gauge Calibration met in Logan, Utah in July 1992 to investigate the various methods of soil sampling, installation of access tubes, effect of various parameters on gauge readings, methods of developing field calibration curves and comparison of neutron gauge characteristics. Details of the overall objectives of the study are covered by Stone (1993, this volume). This paper discusses the soil sampling methods and presents a comparative result based on bulk density, time required for sampling and cost of sampling equipment Other papers developed from this study describe the soils, the three sites investigated and the problems related to the tube installation process

An exact solution to determination of an open orbit

We present an exact solution of the equations for orbit determination of a two body system in a hyperbolic or parabolic motion. In solving this problem, we extend the method employed by Asada, Akasaka and Kasai (AAK) for a binary system in an elliptic orbit. The solutions applicable to each of elliptic, hyperbolic and parabolic orbits are obtained by the new approach, and they are all expressed in an explicit form, remarkably, only in terms of elementary functions. We show also that the solutions for an open orbit are recovered by making a suitable transformation of the AAK solution for an elliptic case.Comment: 28 pages, text improved, references added; version accepted by Celestial Mec

Sociological variety and the transmission efficiency of Mycobacterium tuberculosis: a secondary analysis of qualitative and quantitative data from 15 communities in Zambia

Objectives: Selected Zambian communities formed part of a cluster randomised trial: the Zambia and South Africa TB and AIDS Reduction study (ZAMSTAR). There was wide variability in the prevalence of Mycobacterium tuberculosis infection and tuberculosis (TB) disease across these communities. We sought to clarify whether specific communities could have been more/less vulnerable to M. tuberculosis transmission as a result of sociological variety relevant to transmission efficiency. Design: We conducted a mixed methods secondary analysis using existing data sets. First, we analysed qualitative data to categorise and synthesise patterns of socio-spatial engagement across communities. Second, we compared emergent sociological variables with a measure of transmission efficiency: the ratio of the annual risk of infection to TB prevalence. Setting: ZAMSTAR communities in urban and peri-urban Zambia, spanning five provinces. Participants Fifteen communities, each served by a health facility offering TB treatment to a population of at least 25 000. TB notification rates were at least 400 per 100 000 per annum and HIV seroprevalence was estimated to be high. Results: Crowding, movement, livelihoods and participation in recreational activity differed across communities. Based on 12 socio-spatial indicators, communities were qualitatively classified as more/less spatially crowded and as more/less socially ‘open’ to contact with others, with implications for the presumptive risk of M. tuberculosis transmission. For example, watching video shows in poorly ventilated structures posed a presumptive risk in more socially open communities, while outdoor farming and/or fishing were particularly widespread in communities with lower transmission measures. Conclusions: A dual dynamic of ‘social permeability’ and crowding appeared relevant to disparities in M. tuberculosis transmission efficiency. To reduce transmission, certain socio-spatial aspects could be adjusted (eg, increasing ventilation on transport), while more structural aspects are less malleable (eg, reliance on public transport). We recommend integrating community level typologies with genome sequencing techniques to further explore the significance of ‘social permeability’. Trial registration number: ISRCTN36729271

Pre-M Phase-promoting Factor Associates with Annulate Lamellae in Xenopus Oocytes and Egg Extracts

We have used complementary biochemical and in vivo approaches to study the compartmentalization of M phase-promoting factor (MPF) in prophase Xenopus eggs and oocytes. We first examined the distribution of MPF (Cdc2/CyclinB2) and membranous organelles in high-speed extracts of Xenopus eggs made during mitotic prophase. These extracts were found to lack mitochondria, Golgi membranes, and most endoplasmic reticulum (ER) but to contain the bulk of the pre-MPF pool. This pre-MPF could be pelleted by further centrifugation along with components necessary to activate it. On activation, Cdc2/CyclinB2 moved into the soluble fraction. Electron microscopy and Western blot analysis showed that the pre-MPF pellet contained a specific ER subdomain comprising "annulate lamellae" (AL): stacked ER membranes highly enriched in nuclear pores. Colocalization of pre-MPF with AL was demonstrated by anti-CyclinB2 immunofluorescence in prophase oocytes, in which AL are positioned close to the vegetal surface. Green fluorescent protein-CyclinB2 expressed in oocytes also localized at AL. These data suggest that inactive MPF associates with nuclear envelope components just before activation. This association may explain why nuclei and centrosomes stimulate MPF activation and provide a mechanism for targeting of MPF to some of its key substrates

Origin and Evolution of Saturn's Ring System

The origin and long-term evolution of Saturn's rings is still an unsolved problem in modern planetary science. In this chapter we review the current state of our knowledge on this long-standing question for the main rings (A, Cassini Division, B, C), the F Ring, and the diffuse rings (E and G). During the Voyager era, models of evolutionary processes affecting the rings on long time scales (erosion, viscous spreading, accretion, ballistic transport, etc.) had suggested that Saturn's rings are not older than 100 My. In addition, Saturn's large system of diffuse rings has been thought to be the result of material loss from one or more of Saturn's satellites. In the Cassini era, high spatial and spectral resolution data have allowed progress to be made on some of these questions. Discoveries such as the ''propellers'' in the A ring, the shape of ring-embedded moonlets, the clumps in the F Ring, and Enceladus' plume provide new constraints on evolutionary processes in Saturn's rings. At the same time, advances in numerical simulations over the last 20 years have opened the way to realistic models of the rings's fine scale structure, and progress in our understanding of the formation of the Solar System provides a better-defined historical context in which to understand ring formation. All these elements have important implications for the origin and long-term evolution of Saturn's rings. They strengthen the idea that Saturn's rings are very dynamical and rapidly evolving, while new arguments suggest that the rings could be older than previously believed, provided that they are regularly renewed. Key evolutionary processes, timescales and possible scenarios for the rings's origin are reviewed in the light of tComment: Chapter 17 of the book ''Saturn After Cassini-Huygens'' Saturn from Cassini-Huygens, Dougherty, M.K.; Esposito, L.W.; Krimigis, S.M. (Ed.) (2009) 537-57

Prototype ATLAS IBL Modules using the FE-I4A Front-End Readout Chip

The ATLAS Collaboration will upgrade its semiconductor pixel tracking detector with a new Insertable B-layer (IBL) between the existing pixel detector and the vacuum pipe of the Large Hadron Collider. The extreme operating conditions at this location have necessitated the development of new radiation hard pixel sensor technologies and a new front-end readout chip, called the FE-I4. Planar pixel sensors and 3D pixel sensors have been investigated to equip this new pixel layer, and prototype modules using the FE-I4A have been fabricated and characterized using 120 GeV pions at the CERN SPS and 4 GeV positrons at DESY, before and after module irradiation. Beam test results are presented, including charge collection efficiency, tracking efficiency and charge sharing.Comment: 45 pages, 30 figures, submitted to JINS

Determinants of diagnostic investigation sensitivities across the clinical spectrum of sporadic Creutzfeldt-Jakob disease

To validate the provisional findings of a number of smaller studies and explore additional determinants of characteristic diagnostic investigation results across the entire clinical spectrum of sporadic Creutzfeldt-Jakob disease (CJD), an international collaborative study was undertaken comprising 2451 pathologically confirmed (definite) patients. We assessed the influence of age at disease onset, illness duration, prion protein gene (PRNP) codon 129 polymorphism (either methionine or valine) and molecular sub-type on the diagnostic sensitivity of EEG, cerebral MRI and the CSF 14-3-3 immunoassay. For EEG and CSF 14-3-3 protein detection, we also assessed the influence of the time point in a patient's illness at which the investigation was performed on the likelihood of a typical or positive result. Analysis included a large subset of patients (n = 743) in whom molecular sub-typing had been performed using a combination of the PRNP codon 129 polymorphism and the form of protease resistant prion protein [type 1 or 2 according to Parchi et al. (Parchi P, Giese A, Capellari S, Brown P, Schulz-Schaeffer W, Windl O, Zerr I, Budka H, Kopp N, Piccardo P, Poser S, Rojiani A, Streichemberger N, Julien J, Vital C, Ghetti B, Gambetti P, Kretzschmar H. Classification of sporadic Creutzfeldt-Jakob disease based on molecular and phenotypic analysis of 300 subjects. Ann Neurol 1999; 46: 224-233.)] present in the brain. Findings for the whole group paralleled the subset with molecular sub-typing data available, showing that age at disease onset and disease duration were independent determinants of typical changes on EEG, while illness duration significantly influenced positive CSF 14-3-3 protein detection; changes on brain MRI were not influenced by either of these clinical parameters, but overall, imaging data were less complete and consequently conclusions are more tentative. In addition to age at disease onset and illness duration, molecular sub-type was re-affirmed as an important independent determinant of investigation results. In multivariate analyses that included molecular sub-type, time point of the investigation during a patient's illness was found not to influence the occurrence of a typical or positive EEG or CSF 14-3-3 protein result. A typical EEG was most often seen in MM1 patients and was significantly less likely in the MV1, MV2 and VV2 sub-types, whereas VV2 patients had an increased likelihood of a typical brain MRI. Overall, the CSF 14-3-3 immunoassay was the most frequently positive investigation (88.1%) but performed significantly less well in the very uncommon MV2 and MM2 sub-types. Our findings confirm a number of determinants of principal investigation results in sporadic CJD and underscore the importance of recognizing these pre-test limitations before accepting the diagnosis excluded or confirmed. Combinations of investigations offer the best chance of detection, especially for the less common molecular sub-types such as MV2 and MM2

D* Production in Deep Inelastic Scattering at HERA

This paper presents measurements of D^{*\pm} production in deep inelastic scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The data have been taken with the ZEUS detector at HERA. The decay channel $D^{*+}\to (D^0 \to K^- \pi^+) \pi^+$ (+ c.c.) has been used in the study. The $e^+p$ cross section for inclusive D^{*\pm} production with $5<Q^2<100 GeV^2$ and $y<0.7$ is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region {$1.3<p_T(D^{*\pm})<9.0$ GeV and $| \eta(D^{*\pm}) |<1.5$}. Differential cross sections as functions of p_T(D^{*\pm}), $\eta(D^{*\pm}), W$ and $Q^2$ are compared with next-to-leading order QCD calculations based on the photon-gluon fusion production mechanism. After an extrapolation of the cross section to the full kinematic region in p_T(D^{*\pm}) and $\eta$(D^{*\pm}), the charm contribution $F_2^{c\bar{c}}(x,Q^2)$ to the proton structure function is determined for Bjorken $x$ between 2 $\cdot$ 10$^{-4}$ and 5 $\cdot$ 10$^{-3}$.Comment: 17 pages including 4 figure

Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the $\gamma p$ centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil