8 resultados para Ramon

em CentAUR: Central Archive University of Reading - UK


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Calliandra calothyrsus is a tree legume native to Mexico and Central America. The species has attracted considerable attention for its capacity to produce both fuelwood and foliage for either green manure or fodder. Its high content of proanthocyanidins (condensed tannins) and associated low digestibility has, however, limited its use as a feed for ruminants, and there is also a widespread perception that wilting the leaves further reduces their nutritive value. Nevertheless, there has been increasing uptake of calliandra as fodder in certain regions, notably the Central Highlands of Kenya. The present study, conducted in Embu, Kenya, investigated effects of provenance, wilting, cutting frequency and seasonal variation both in the laboratory (in vitro digestibility, crude protein, neutral detergent fibre, extractable and bound proanthocyanidins) and in on-station animal production trials with growing lambs and lactating goats. The local Kenyan landrace of calliandra (Embu) and a closely-related Guatemalan provenance (Patulul) were found to be significantly different, and superior, to a provenance from Nicaragua (San Ramon) in most of the laboratory traits measured, as well as in animal production and feed efficiency. Cutting frequency had no important effect on quality; and although all quality traits displayed seasonal variation there was little discernible pattern to this variation. Wilting had a much less negative effect than expected, and for lambs fed calliandra as a supplement to a low quality basal feed (maize stover), wilting was actually found to give higher live-weight gain and feed efficiency. Conversely, with a high quality basal diet (Napier grass) wilting enhanced intake but not live-weight gain, so feed efficiency was greater for fresh material. The difference between fresh and wilted leaves was not great enough to justify the current widespread recommendation that calliandra should always be fed fresh.

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The syntheses, spectroscopic characterisation and in one case (X = Br) the single-crystal structure of the novel PdI–PdI dimers [Pd2(µ-X)2(PBut3)2](X = Br or I) have been determined; preliminary results on their reactions with CO, H2, CNC6H3Me2 and C2H2 have also been obtained.

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We describe herein preliminary studies on the Intramolecular Diels-Alder Furan-Mediated Synthesis of 8-Aryl-3, 4-di-hydroisoquinolin-1(2H)-ones that constitutes a new, formal synthesis of Indeno[1,2,3-ij]isoquinolines.

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Satellite data are increasingly used to provide observation-based estimates of the effects of aerosols on climate. The Aerosol-cci project, part of the European Space Agency's Climate Change Initiative (CCI), was designed to provide essential climate variables for aerosols from satellite data. Eight algorithms, developed for the retrieval of aerosol properties using data from AATSR (4), MERIS (3) and POLDER, were evaluated to determine their suitability for climate studies. The primary result from each of these algorithms is the aerosol optical depth (AOD) at several wavelengths, together with the Ångström exponent (AE) which describes the spectral variation of the AOD for a given wavelength pair. Other aerosol parameters which are possibly retrieved from satellite observations are not considered in this paper. The AOD and AE (AE only for Level 2) were evaluated against independent collocated observations from the ground-based AERONET sun photometer network and against “reference” satellite data provided by MODIS and MISR. Tools used for the evaluation were developed for daily products as produced by the retrieval with a spatial resolution of 10 × 10 km2 (Level 2) and daily or monthly aggregates (Level 3). These tools include statistics for L2 and L3 products compared with AERONET, as well as scoring based on spatial and temporal correlations. In this paper we describe their use in a round robin (RR) evaluation of four months of data, one month for each season in 2008. The amount of data was restricted to only four months because of the large effort made to improve the algorithms, and to evaluate the improvement and current status, before larger data sets will be processed. Evaluation criteria are discussed. Results presented show the current status of the European aerosol algorithms in comparison to both AERONET and MODIS and MISR data. The comparison leads to a preliminary conclusion that the scores are similar, including those for the references, but the coverage of AATSR needs to be enhanced and further improvements are possible for most algorithms. None of the algorithms, including the references, outperforms all others everywhere. AATSR data can be used for the retrieval of AOD and AE over land and ocean. PARASOL and one of the MERIS algorithms have been evaluated over ocean only and both algorithms provide good results.

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The fair weather atmospheric electrical current (Jz) couples the ionosphere to the lower atmosphere and thus provides a route by which changes in solar activity can modify processes in the lower troposphere. This paper examines the temporal variations and spectral characteristics of continuous measurements of Jz conducted at the Wise Observatory in Mitzpe-Ramon, Israel (30°35′ N, 34°45′ E), during two large CMEs, and during periods of increased solar wind density. Evidence is presented for the effects of geomagnetic storms and sub-storms on low latitude Jz during two coronal mass ejections (CMEs), on 24–25th October 2011 and 7–8th March 2012, when the variability in Jz increased by an order of magnitude compared to normal fair weather conditions. The dynamic spectrum of the increased Jz fluctuations exhibit peaks in the Pc5 frequency range. Similar low frequency characteristics occur during periods of enhanced solar wind proton density. During the October 2011 event, the periods of increased fluctuations in Jz lasted for 7 h and coincided with fluctuations of the inter-planetary magnetic field (IMF) detected by the ACE satellite. We suggest downward mapping of ionospheric electric fields as a possible mechanism for the increased fluctuations.

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Within the ESA Climate Change Initiative (CCI) project Aerosol_cci (2010–2013), algorithms for the production of long-term total column aerosol optical depth (AOD) datasets from European Earth Observation sensors are developed. Starting with eight existing pre-cursor algorithms three analysis steps are conducted to improve and qualify the algorithms: (1) a series of experiments applied to one month of global data to understand several major sensitivities to assumptions needed due to the ill-posed nature of the underlying inversion problem, (2) a round robin exercise of "best" versions of each of these algorithms (defined using the step 1 outcome) applied to four months of global data to identify mature algorithms, and (3) a comprehensive validation exercise applied to one complete year of global data produced by the algorithms selected as mature based on the round robin exercise. The algorithms tested included four using AATSR, three using MERIS and one using PARASOL. This paper summarizes the first step. Three experiments were conducted to assess the potential impact of major assumptions in the various aerosol retrieval algorithms. In the first experiment a common set of four aerosol components was used to provide all algorithms with the same assumptions. The second experiment introduced an aerosol property climatology, derived from a combination of model and sun photometer observations, as a priori information in the retrievals on the occurrence of the common aerosol components. The third experiment assessed the impact of using a common nadir cloud mask for AATSR and MERIS algorithms in order to characterize the sensitivity to remaining cloud contamination in the retrievals against the baseline dataset versions. The impact of the algorithm changes was assessed for one month (September 2008) of data: qualitatively by inspection of monthly mean AOD maps and quantitatively by comparing daily gridded satellite data against daily averaged AERONET sun photometer observations for the different versions of each algorithm globally (land and coastal) and for three regions with different aerosol regimes. The analysis allowed for an assessment of sensitivities of all algorithms, which helped define the best algorithm versions for the subsequent round robin exercise; all algorithms (except for MERIS) showed some, in parts significant, improvement. In particular, using common aerosol components and partly also a priori aerosol-type climatology is beneficial. On the other hand the use of an AATSR-based common cloud mask meant a clear improvement (though with significant reduction of coverage) for the MERIS standard product, but not for the algorithms using AATSR. It is noted that all these observations are mostly consistent for all five analyses (global land, global coastal, three regional), which can be understood well, since the set of aerosol components defined in Sect. 3.1 was explicitly designed to cover different global aerosol regimes (with low and high absorption fine mode, sea salt and dust).

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Cosmic ray fluxes in the atmosphere were recorded during balloon flights in October 2014 in northern Murmansk region, Apatity (Russia; 67o33’N, 33o24’E), in Antarctica (observatory Mirny; 66o33’S, 93o00’E), in Moscow (Russia; 55o45’N, 37o37’E), in Reading (United King-dom; 51o27’N, 0o 58’W), in Mitzpe-Ramon (Israel; 30o36’N, 34o48’E) and in Zaragoza (Spain; 41o9’N, 0o54’W). Two type of cosmic ray detectors were used, namely, (1) the standard ra-diosonde and its modification constructed at the Lebedev Physical Institute (Moscow, Russia) and (2) the device manufactured at the Reading University (Reading, United Kingdom). We compare and analyze obtained data and focus on the estimation of the cosmic ray latitudinal effect in the atmosphere.

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Group show, curated by Invisible Exports Gallery. Featuring work by Michael Bilsborough, Lizzi Bougatsos, BREYER P-ORRIDGE, Asger Carlsen, Troels Carlsen, Walt Cassidy, Andy Coolquitt, Vaginal Davis, Carlton DeWoody, Joey Frank, Paul Gabrielli, Ludovica Gioscia, Luis Gispert, Terence Hannum, Karen Heagle, Timothy Hull, Doug Ischar, Brian Kenny, Jeremy Kost, Aaron Krach, Yeni Mao, Leigha Mason, Mark McCoy, Robert Melee, Lucas Michael, Jennifer Needleman, Brent Owens, Paul P., Paolo Di Paolo, Franklin Preston, John Russell, Xaviera Simmons, Duston Spear, Scott Treleaven, Ramon Vega, Jordan Wolfson, Dustin Yellin