773 research outputs found

    Notes of Orchids from AndalucĂ­a. II

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    Notas de OrquĂ­deas de Andalucia II. Palabras clave. Orchidaceae, AndalucĂ­a, Espana.Key Words. Orchidaceae, AndalucĂ­a, Spain

    Re-identification of c. 15 700 cal yr BP tephra bed at Kaipo Bog, eastern North Island: implications for dispersal of Rotorua and Puketarata tephra beds.

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    A 10 mm thick, c. 15 700 calendar yr BP (c. 13 100 14C yr BP) rhyolitic tephra bed in the well-studied montane Kaipo Bog sequence of eastern North Island was previously correlated with Maroa-derived Puketarata Tephra. We revise this correlation to Okataina-derived Rotorua Tephra based on new compositional data from biotite phenocrysts and glass. The new correlation limits the known dispersal of Puketarata Tephra (sensu stricto, c. 16 800 cal yr BP) and eliminates requirements to either reassess its age or to invoke dual Puketarata eruptive events. Our data show that Rotorua Tephra comprises two glass-shard types: an early-erupted low-K2O type that was dispersed mostly to the northwest, and a high-K2O type dispersed mostly to the south and southeast, contemporary with late-stage lava extrusion. Late-stage Rotorua eruptives contain biotite that is enriched in FeO compared with biotite from Puketarata pyroclastics. The occurrence of Rotorua Tephra in Kaipo Bog (100 km from the source) substantially extends its known distribution to the southeast. Our analyses demonstrate that unrecognised syn-eruption compositional and dispersal changes can cause errors in fingerprinting tephra deposits. However, the compositional complexity, once recognised, provides additional fingerprinting criteria, and also documents magmatic and dispersal processes

    Practical methods of tracking of nonstationary time series applied to real-world data

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    In this paper, we discuss some practical implications for implementing adaptable network algorithms applied to non-stationary time series problems. Two real world data sets, containing electricity load demands and foreign exchange market prices, are used to test several different methods, ranging from linear models with fixed parameters, to non-linear models which adapt both parameters and model order on-line. Training with the extended Kalman filter, we demonstrate that the dynamic model-order increment procedure of the resource allocating RBF network (RAN) is highly sensitive to the parameters of the novelty criterion. We investigate the use of system noise for increasing the plasticity of the Kalman filter training algorithm, and discuss the consequences for on-line model order selection. The results of our experiments show that there are advantages to be gained in tracking real world non-stationary data through the use of more complex adaptive models

    Preliminary Sunyaev Zel'dovich Observations of Galaxy Clusters with OCRA-p

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    We present 30 GHz Sunyaev Zel'dovich (SZ) observations of a sample of four galaxy clusters with a prototype of the One Centimetre Receiver Array (OCRA-p) which is mounted on the Torun 32-m telescope. The clusters (Cl0016+16, MS0451.6-0305, MS1054.4-0321 and Abell 2218) are popular SZ targets and serve as commissioning observations. All four are detected with clear significance (4-6 sigma) and values for the central temperature decrements are in good agreement with measurements reported in the literature. We believe that systematic effects are successfully suppressed by our observing strategy. The relatively short integration times required to obtain these results demonstrate the power of OCRA-p and its successors for future SZ studies.Comment: 9 pages, 2 figures. Accepted by MNRAS, online earl

    Requirements for a global lidar system: spaceborne lidar with wall-to-wall coverage

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    Lidar is the optimum technology for measuring bare Earth elevation beneath, and the structure of, vegetation. Consequently airborne laser scanning (ALS) is widely employed for use in a wide range of applications. However, ALS is not available globally nor frequently updated due to its high cost per unit area. Spaceborne lidar can map globally, but energy requirements limit existing spaceborne lidars to sparse sampling missions unsuitable for many common ALS applications. This paper derives the equations to calculate the coverage a lidar satellite could achieve for a given set of characteristics (and released open-source), then uses a cloud map to determine the number of satellites needed to achieve continuous, global coverage within a certain time-frame. Using the characteristics of existing in-orbit technology, a single lidar satellite could have a continuous swath width of 300 m when producing a 30 m resolution map. Consequently 12 satellites would be needed to produce a continuous map every five years, increasing to 418 satellites for 5 m resolution. Building twelve of the currently in-orbit lidar systems is likely to be prohibitively expensive and so the potential of technological developments to lower the cost of a GLS are discussed. Once these technologies achieve a sufficient readiness level, a Global Lidar System could be cost-effectively realised

    Metabolic, inflammatory and haemostatic effects of a low-dose continuous combined HRT in women with type 2 diabetes: potentially safer with respect to vascular risk?

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    BACKGROUND Conventional hormone replacement therapy (HRT) containing conjugated equine oestrogen (CEE) and medroxyprogesterone acetate (MPA) increases triglyceride, C- reactive protein (CRP) and coagulation Factor VII concentrations, potentially explaining their increased coronary heart disease (CHD) and stroke risk. OBJECTIVE To assess the metabolic effects of a continuous combined HRT containing 1 mg oestradiol and 0.5 mg norethisterone or matching placebo. DESIGN Double-blind, randomized placebo-controlled trial. PATIENTS Fifty women with type 2 diabetes. MEASUREMENTS Classical and novel risk factors for vascular disease. RESULTS Triglyceride concentration was not altered (P = 0.31, change in active arm relative to placebo) and low-density lipoprotein (LDL) cholesterol concentration declined 13% (P = 0.018). IL-6 concentration (mean difference -1.42 pg/ml, 95% CI: -2.55 to - 0.29 IU/dl, P = 0.015), Factor VII (-32 IU/dl, -43 to -21 IU/l, P lt 0.001) and tissue plasminogen activator antigen (by 13%, P = 0.005) concentrations fell, but CRP was not significantly altered (P = 0.62). Fasting glucose (P = 0.026) also declined significantly, but there are no significant effects on HBA1c, Factor IX or APC resistance. CONCLUSIONS HRT containing 1 mg oestradiol and 0.5 mg norethisterone may avoid the adverse metabolic effects potentially implicated in the elevated CHD and stroke risk induced by conventional higher dose HRT. This type of preparation may therefore be more suitable than conventional HRT for women at elevated CHD risk such as those with type 2 diabetes. Large randomized controlled trials of such low dose preparations, powered for cardiovascular end points, are now needed

    In vitro anthelmintic effects of cysteine proteinases from plants against intestinal helminths of rodents

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    Infections with gastrointestinal (GI) nematodes are amongst the most prevalent worldwide, especially in tropical climates. Control of these infections is primarily through treatment with anthelmintic drugs, but the rapid development of resistance to all the currently available classes of anthelmintic means that alternative treatments are urgently required. Cysteine proteinases from plants such as papaya, pineapple and fig are known to be substantially effective against three rodent GI nematodes, Heligmosomoides polygyrus, Trichuris muris and Protospirura muricola, both in vitro and in vivo. Here, based on in vitro motility assays and scanning electron microscopy, we extend these earlier reports, demonstrating the potency of this anthelmintic effect of plant cysteine proteinases against two GI helminths from different taxonomic groups – the canine hookworm, Ancylostoma ceylanicum, and the rodent cestode, Rodentolepis microstoma. In the case of hookworms, a mechanism of action targeting the surface layers of the cuticle indistinguishable from that reported earlier appears to be involved, and in the case of cestodes, the surface of the tegumental layers was also the principal location of damage. Hence, plant cysteine proteinases have a broad spectrum of activity against intestinal helminths (both nematodes and cestodes), a quality that reinforces their suitability for development as a muchneeded novel treatment against GI helminths of humans and livestock

    Enzymatic radiosynthesis of a 18F-Glu-Ureido-Lys ligand for the prostate-specific membrane antigen (PSMA)

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    We thank the Engineering and Physical Sciences Research Council, UK, for a research grant (EP/M01262X/1).Peer reviewedPostprin

    On the timing of retreat of the Loch Lomond (‘Younger Dryas’) Readvance icefield in the SW Scottish Highlands and its wider significance

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    It has long been assumed that the last glacier expansion in the Scottish Highlands, the Loch Lomond Readvance (LLR), resulted from a cold reversal that was broadly coeval with the ‘Younger Dryas’ episode. This view has recently been challenged, with the suggestion that glacier ice had disappeared from Rannoch Moor, one of the main ice accumulation centres in the SW Scottish Highlands, by as early as 12.5 ka, i.e. within the first half of the ‘Younger Dryas’. Here we present new radiocarbon, tephrostratigraphical and pollen-stratigraphical evidence from one of the key sites on Rannoch Moor, the results of an experiment designed to test this hypothesis. Our results not only contradict that concept, but are fully compatible with other evidence from the SW Scottish Highlands that suggests that the LLR glaciers in this area continued to expand until towards the end of the ‘Younger Dryas’ period, and may have persisted in some places after the onset of the Holocene. We consider the possible reasons for this marked divergence in chronology, a matter that is crucial to resolve because the precise timing of the demise of the LLR glaciers has important palaeoclimatic and other implications. In the wider context, we also draw attention to problems with the general use of the term ‘Younger Dryas’ and why we regard the Greenland stratotype unit and term ‘Greenland Stadial 1’ (GS-1) a more secure stratigraphic comparator

    Detection and characterisation of Eemian marine tephra layers within the sapropel S5 sediments of the Aegean and Levantine Seas

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    The Eemian was the last interglacial period (~130 to 115 ka BP) to precede the current interglacial. In Eastern Mediterranean marine sediments, it is marked by a well-developed and organic-rich “sapropel” layer (S5), which is thought to reflect an intensification and northward migration of the African monsoon rain belt over orbital timescales. However, despite the importance of these sediments, very little proxy-independent stratigraphic information is available to enable rigorous correlation of these sediments across the region. This paper presents the first detailed study of visible and non-visible (cryptotephra) layers found within these sediments at three marine coring sites: ODP Site 967B (Levantine Basin), KL51 (South East of Crete) and LC21 (Southern Aegean Sea). Major element analyses of the glass component were used to distinguish four distinct tephra events of Santorini (e.g., Vourvoulos eruption) and possible Anatolian provenance occurring during the formation of S5. Interpolation of core chronologies provides provisional eruption ages for the uppermost tephra (unknown Santorini, 121.8 ± 2.9 ka) and lowermost tephra (Anatolia or Kos/Yali/Nisyros, 126.4 ± 2.9 ka). These newly characterised tephra deposits have also been set into the regional tephrostratigraphy to illustrate the potential to precisely synchronise marine proxy records with their terrestrial counterparts, and also contribute to the establishment of a more detailed volcanic history of the Eastern Mediterranean
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