1,251 research outputs found

    The role of space borne imaging radars in environmental monitoring: Some shuttle imaging radar results in Asia

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    The synoptic view afforded by orbiting Earth sensors can be extremely valuable for resource evaluation, environmental monitoring and development planning. For many regions of the world, however, cloud cover has prevented the acquisition of remotely sensed data during the most environmentally stressful periods of the year. How synthetic aperture imaging radar can be used to provide valuable data about the condition of the Earth's surface during periods of bad weather is discussed. Examples are given of applications using data from the Shuttle Imaging Radars (SIR) A and B for agricultural land use and crop condition assessment, monsoon flood boundary and flood damage assessment, water resource monitoring and terrain modeling, coastal forest mapping and vegetation penetration, and coastal development monitoring. Recent SIR-B results in Bangladesh are emphasized, radar system basics are reviewed and future SAR systems are discussed

    Internal Migration and Regional Population Dynamics in Europe: Netherlands Case Study

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    This report summarises the presentations made and discussions held at the Second of the ESRC/JISC Workshops Planning for the 2001 Census. The report presents views of expert census users and summarises the recommendations to ESRC and JISC about what kinds of data from the 2001 Census should be requested from the UK Census Offices. The Workshops are supported by ESRC Award H507265031. The Census of Population is a very large exercise in data collection and processing. In 2001 some 25 million households in the United Kingdom will be contacted and asked to provide answers to a simple questionnaire of 25 to 30 questions. Such a task is likely to cost £125-150 millions to the Census Offices. Purchase of the data for academic research purposes is likely to cost ESRC and JISC some £1.5 to £2 millions directly and an equivalent amount indirectly on support over the following decade. It is therefore essential that the Population Census is very carefully planned beforehand and that the greatest possible value is extracted from the data collected. This edited collection of papers reports on presentations and discussions in the Fourth and Final Workshop in the series Workshops Planning for the 2001 Census - Determining Academic Community Needs and Strategy. The Fourth Workshop was entitled The 2001 Census: What do we really really want?. The aim was to gather together and summarise the principal recommendations of the First (Geography), Second (Interfaces) and Third (Special Data Sets) Workshops. The Workshop was twinned with another on The One Number Census: A Research Workshop, organised by Ludi Simpson. The One Number Census project is a major undertaking by the Census Offices to deal with anticipated underenumeration by estimating how many households and people are missed by the standard enumeration. Part 1 of the report on Look Up Tables and Area Statistics contains chapters by David Martin on the output geography proposals for 2001, by Seraphim Alvanides and Stan Openshaw on further developments to the methods being used to define output areas and by Bob Barr on what the Look Up Tables associated with the 2001 Census should be like. These chapters contain key recommendations on census output geography. Part 2 of the report puts forward recommendations for the preparation of Microdata - Samples of Anonymised Records and Longitudinal Data from the 2001 Census. Angela Dale summarises the conclusions of the SARs Sub-Group of the Census Offices' Output Working Group. Brian Dodgeon and Heather Joshi document the essential features of the 2001 Census Link to the Longitudinal Study and make a final plea for some new questions. Part 3 of the report reviews proposals for the improvement of Interaction Statistics from the 2001 UK Census. Paul Boyle and Phil Rees make radical proposals for revamping the provision of Migration Statistics. Martin Frost concentrates on ways of improving the accuracy of the Workplace Statistics. The fourth part of the report gathers together recommendations about information technology interfaces to census data, arguing that the tools and infrastructure are now in place to make networked and standalone access to the different types of data so much easier for the new user. Donald Morse and Alistair Towers review what interfaces to boundary data should look like. James Harris argues for the development of interfaces based on general data standards and the Web to access census statistics. Oliver Duke-Williams outlines how complex migration statistics can be presented for access in a simpler and easier to use interface. Ian Turton identifies how current software developments in Java programming will make possible delivering easy to use interfaces to microdata very simple. Finally, Paul Williamson describes a design of a data dictionary for all census data sets. In Part 5, recommendations are summarised. Phil Rees reports on the views of 140 respondents drawn from the different corners of the academic community. The final pages try to draw out some general points from the very large number of recommendations made in the Fourth Workshop

    Secondary metabolites from Calotropis procera (Aiton)

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    Three new metabolites, 5-hydroxy-3,7-dimethoxyflavone-4′-O-β-glucopyranoside (1), 2β,19-epoxy-3β,14β-dihydroxy-19-methoxy-5α-card-20(22)-enolide (4) and β-anhydroepidigitoxigenin-3β-O-glucopyranoside (5), along with two known compounds, uzarigenine (2) and β-anhydroepidigitoxigenin (3), were isolated from Calotropis procera (Asclepiadaceae). The structure elucidation was accomplished mainly by nuclear magnetic resonance (NMR) spectroscopic and mass spectrometric methods. To examine putative antimicrobial or cytotoxic activities, various bioassays were performed. Uzarigenine (2) demonstrated moderate cytotoxicity

    A three dimensional model of the photosynthetic membranes of Ectothiorhodospira halochloris

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    The three dimensional organization of the complete photosynthetic apparatus of the extremely halophilic, bacteriochlorophyll b containing Ectothiorhodospira halochloris has been elaborated by several techniques of electron microscopy. Essentially all thylakoidal sacs are disc shaped and connected to the cytoplasmic membrane by small membraneous ldquobridgesrdquo. In sum, the lumina of all thylakoids (intrathylakoidal space) form one common periplasmic space. Thin sections confirm a paracrystalline arrangement of the photosynthetic complexes in situ. The ontogenic development of the photosynthetic apparatus is discussed based on a structural model derived from serial thin sections

    Ultraviolet and Multiwavelength Variability of the Blazar 3C 279: Evidence for Thermal Emission

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    The gamma-ray blazar 3C 279 was monitored on a nearly daily basis with IUE, ROSAT and EGRET for three weeks between December 1992 and January 1993. During this period, the blazar was at a historical minimum at all wavelengths. Here we present the UV data obtained during the above multiwavelength campaign. A maximum UV variation of ~50% is detected, while during the same period the X-ray flux varied by no more than 13%. At the lowest UV flux level the average spectrum in the 1230-2700 A interval is unusually flat for this object (~1). The flattening could represent the lowest energy tail of the inverse Compton component responsible for the X-ray emission, or could be due to the presence of a thermal component at ~20000 K possibly associated with an accretion disk. The presence of an accretion disk in this blazar object, likely observable only in very low states and otherwise hidden by the beamed, variable synchrotron component, would be consistent with the scenario in which the seed photons for the inverse Compton mechanism producing the gamma-rays are external to the relativistic jet. We further discuss the long term correlation of the UV flux with the X-ray and gamma-ray fluxes obtained at various epochs. All UV archival data are included in the analysis. Both the X- and gamma-ray fluxes are generally well correlated with the UV flux, approximately with square root and quadratic dependences, respectively.Comment: 22 pages, Latex, 7 PostScript figures, to appear in The Astrophysical Journa

    Actinomycetospora chiangmaiensis gen. nov., sp. nov., a new member of the family Pseudonocardiaceae

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    A novel actinonmycete strain, YIM 0006(T), was isolated from soil of a tropical rainforest in northern Thailand. The isolate displayed the following characteristics: aerial mycelium is absent, short spore chains are formed directly on the substrate mycelium, contains meso-diaminopimelic acid, arabinose and galactose (cell-wall chemotype IV), the diagnostic phospholipid is phosphaticlylcholine, MK-9(H-4) is the predominant menaquinone and the G + C content of the genomic DNA is 69.0 mol%. Phylogenetic analysis and phenotypic characteristics showed that strain YIM 0006(T) belongs to the family Pseudonocardiaceae but can be distinguished from representatives of all genera classified in the family. The novel genus and species Actinomycetospora chiangmaiensis gen. nov., sp. nov. are proposed, with strain YIM 0006(T) (=CCTCC AA 205017(T) =DSM 45062(T)) as the type strain of Actinomycetospora chiangmaiensis

    Sol-gel synthesis and multiferroic properties of pyrochlore-free Pb(Fe0.5Nb0.5)O3 thin films

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    Lead iron niobate (PbFe0.5Nb0.5O3 - PFN) thin films were synthesized by a modified sol-gel route, which offers the advantage of a rapid, simple and non-toxic reaction method. Polycrystalline perovskite-structured PFN thin films without pyrochlore phases were obtained on Pt/Ti/SiO2/Si substrates after sintering by rapid thermal annealing at 650 {\deg}C. TEM and AFM images confirmed the excellent quality of the sintered film, while EDS spectroscopy revealed the presence of oxygen vacancies near the film/substrate interface. Electric measurements show good dielectric properties and ferroelectric behavior, characterized by typical C-V curves and well-defined P-E ferroelectric loops at 1 kHz, with remanent polarization values of ~12 uC/cm2. The polarization, however, increases with decreasing frequency, indicating the presence of leakage currents. I-V measurements show a significant increase in DC-conduction at relatively low fields (around 100 kV/cm). The films display ferromagnetic behavior at room temperature, with magnetic remanence around 30 emu/cm3 and a coercive field of 1 kOe. These values are significantly higher than those obtained for PFN powders fabricated by the same sol-gel route, as well as the magnetization values reported in the literature for epitaxial films.Comment: 24 pages, 10 figure
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