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71.
The European Water Framework Directive requires the definition of reference conditions for each type of surface waters as a base to establish a classification system in which deviations from this high quality status must be determined. In order to reconstruct pristine conditions in the lower river Spree we investigated palaeomeanders using palaeohydrological and palaeolimnological methods. The settlement history of this region suggests low anthropogenic impact for all periods before ~700 cal AD. Three palaeomeanders representing the conditions of the late Sub‐boreal/early Sub‐atlantic were investigated. River width and depth at bankfull stage were reconstructed using cross‐sections of the meanders. Based on these data and experiments on the recent river, a parametric model was developed to calculate the bankfull palaeodischarge. Reconstructions show narrower and shallower channels for the undisturbed lower Spree (~20 m mean width and 0.8 m mean depth at bankfull stage) as compared to recent conditions (35 m and 1.6 m, respectively). Flow velocities and discharge at bankfull stage have been smaller in reconstructed sub‐fossil channels (0.5 m s?1 and 8 m3 s?1 in the pristine lower Spree as compared to 0.9 m s?1 and 52 m3 s?1 in the recent lower Spree) and flow variability was higher. The increase in bankfull discharge was mainly attributed to deforestation and drainage of the catchment as well as channelization, bank protection and river regulation measures. The organic silt at the base of the sediment cores contained well‐preserved fossil diatom assemblages. Diatom‐inferred total phosphorus (DI‐TP) concentrations of 59–73 µg L?1 (median 62 µg L?1) indicate eutrophic to hypertrophic conditions and suggest naturally slightly lower nutrient levels than today. These past nutrient conditions, morphology and large numbers of macrofossil remains indicate optimum growth conditions for submerged macrophytes growth. The combination of palaeohydrological and palaeolimnological parameters proved to be a useful approach for the determination of pristine conditions in a lowland river. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
72.
Carrots washed and packed by hand or machine and stored at 2, 10 or 20 °C in three different package types were analysed for taste, flavour and content of sugars, terpenes, 6‐methoxymellein and ethanol as well as for ethylene, CO2 and O2 concentrations in the packages. Carrots washed by machine had increased micro‐organism decay and higher sensory scores for bitter taste, aftertaste, terpene flavour and odour, green odour and earthy flavour. The ability of packages to ventilate was important to avoid anaerobic conditions that caused decreased sucrose content, increased production of ethanol and a higher intensity of ethanol flavour and sickeningly sweet taste. Increasing temperature enhanced the concentration of ethanol, CO2 and ethylene and decreased the O2 concentration as well as the content of sucrose and total sugar. High temperature also increased the intensity of ethanol flavour and odour, aftertaste, earthy flavour, terpene flavour and bitter taste. Bitter taste was positively correlated with 6‐methoxymellein level, although this level was below the sensory threshold. Bitter taste, earthy flavour and aftertaste were correlated with total terpenes and several individual terpenes. Carrots washed and packed early in the long‐term storage period (November) were more bitter and had a higher level of 6‐methoxymellein and a higher intensity of terpene flavour and odour, green flavour and earthy flavour than those handled in January or March. Copyright © 2004 Society of Chemical Industry  相似文献   
73.
The relationship between semantic–syntactic and phonological levels in speaking was investigated using a picture naming procedure with simultaneously presented visual or auditory distractor words. Previous results with auditory distractors have been used to support the independent stage model (e.g., H. Schriefers, A. S. Meyer, & W. J. M. Levelt, 1990), whereas results with visual distractors have been used to support an interactive view (e.g., P. A. Starreveld & W. La Heij, 1996). Experiment 1 demonstrated that with auditory distractors, semantic effects preceded phonological effects, whereas the reverse pattern held for visual distractors. Experiment 2 indicated that the results for visual distractors followed the auditory pattern when distractor presentation time was limited. Experiment 3 demonstrated an interaction between phonological and semantic relatedness of distractors for auditory presentation, supporting an interactive account of lexical access in speaking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
74.
In this study, a model alloy without Fe and Mn additions, is compared with a commercial AA6005 alloy to further understand how the α-Al(Fe,Mn,Cu)Si particles affect intergranular corrosion (IGC) behaviour. Both alloys were subjected to an accelerated IGC test for durations ranging from 1 to 120 h. Microstructures were studied using scanning and transmission electron microscopy, and electron backscatter diffraction. The presence of α-Al(Fe,Mn,Cu)Si particles yields significantly more uniform IGC attacks and higher corrosion rates. However, the maximum depth of IGC attacks reaches similar values after ~24 h of exposure. This is attributed to the formation of Cu-rich particles along the grain boundaries during the corrosion process, which further catalyses the cathodic reactions.  相似文献   
75.
Secondary phases and grain boundaries in LaCoO3 and La0.7Sr0.3CoO3−δ ceramics have been studied by transmission electron microscopy. Both materials contained small amounts of grains of a secondary phase; the face centered cubic spinel structure Co3O4, located at triple junctions. These grains were agglomerates of several smaller grains. High resolution electron microscopy combined with annular dark field scanning transmission electron microscopy and electron energy loss spectroscopy were used to analyze the grain boundaries. In LaCoO3, the grain boundaries were sharp with stable compositions of La, Co and O across the boundaries. In La0.7Sr0.3CoO3−δ, a 1–2 nm thick intergranular layer between the grains was observed. This layer was rich in O and Co and deficient in Sr and La, compared to the nominal composition of the material.  相似文献   
76.
77.
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder affecting subjects (premutation carriers) with a 55-200 CGG-trinucleotide expansion in the 5′UTR of the fragile X mental retardation 1 gene (FMR1) typically after age 50. As both the presence of white matter hyperintensities (WMHs) and atrophied gray matter on magnetic resonance imaging (MRI) are linked to age-dependent decline in cognition, here we tested whether MRI outcomes (WMH volume (WMHV) and brain volume) were correlated with mitochondrial bioenergetics from peripheral blood monocytic cells in 87 carriers with and without FXTAS. As a parameter assessing cumulative damage, WMHV was correlated to both FXTAS stages and age, and brain volume discriminated between carriers and non-carriers. Similarly, mitochondrial mass and ATP production showed an age-dependent decline across all participants, but in contrast to WMHV, only FADH2-linked ATP production was significantly reduced in carriers vs. non-carriers. In carriers, WMHV negatively correlated with ATP production sustained by glucose-glutamine and FADH2-linked substrates, whereas brain volume was positively associated with the latter and mitochondrial mass. The observed correlations between peripheral mitochondrial bioenergetics and MRI findings—and the lack of correlations with FXTAS diagnosis/stages—may stem from early brain bioenergetic deficits even before overt FXTAS symptoms and/or imaging findings.  相似文献   
78.
The presence and specificity of antiplatelet autoantibodies in 32 patients with primary and 18 patients with secondary autoimmune thrombocytopenic purpura (AITP), as well as 11 non-thrombocytopenic patients with systemic autoimmune diseases, were studied. By means of the direct and indirect monoclonal antibody immobilization of platelet antigen (MAIPA) assay, antiplatelet autoantibodies were detected using monoclonal antibodies specific for platelet glycoproteins (GPs) Ib, IIb/IIIa, Ia/IIa, and IV. Serum antiplatelet autoantibodies were found in 18 of 32 primary AITP patients (56%), 6 of 18 secondary AITP patients (33%), and 5 of 11 nonthrombocytopenic patients (45%). Platelet-associated autoantibodies were detected in five of eight patients with primary (62%) and in four of eight patients with secondary AITP (50%) and in two of four patients without thrombocytopenia (50%). Multiple antibody reactivity, mainly against GPs IIb/IIIa and Ib and, in a few patients, against Ia/IIa, was found. Using MAIPA, platelet xylene eluates from 20 patients were also studied. Antiplatelet elutable autoantibodies were related to thrombocytopenia; autoantibodies against membrane GPs Ib and IIb/IIIa were demonstrable in 84 and 63% of eluates from patients with primary and secondary AITP, respectively, but not in eluates from nonthrombocytopenic patients. The presence of antiplatelet antibodies thus appears to be a common feature of many autoimmune diseases apart from the thrombocytopenia, but the (primary or secondary) etiology of the immune thrombocytopenia cannot be differentiated on the grounds of their specificity.  相似文献   
79.
Health anxiety had been somewhat neglected for years as it by nature evades clear diagnostic boundaries, wavering between a somatoform disorder, an anxiety disorder, and in some cases, a delusional disorder. Recently, the topic of health anxiety has received increasing attention, primarily from leaders in the anxiety disorders field, as reflected in the growing literature on the topic. The book "Treating Health Anxiety: A Cognitive-Behavioral Approach" (see record 2005-04429-000), reviewed in this article, is a timely and much needed addition to this area that will appeal to both clinicians and researchers alike. The book's authors have done a fine job producing a comprehensive book on health anxiety that is well written, interesting, and provides broad coverage of the nature, assessment, and treatment of health anxiety. The use of case examples throughout and the relatively short chapters certainly make this an interesting and quick read. This book will be especially useful for clinicians treating the full range of health anxiety, including hypochondriasis, disease phobia, somatic delusion, or any disorder characterized by excessive anxiety about one's health. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
80.
目的 超分辨率技术在实际生活中具有较为广泛的应用。经典的基于卷积神经网络的超分辨率(SRCNN)方法存在重建图像纹理结构模糊以及网络模型训练收敛过慢等问题。针对这两个问题,在SRCNN的基础上,提出一种多通道卷积的图像超分辨率(MCSR)算法。方法 通过增加残差链接,选择MSRA初始化方法对网络权值进行初始化,加快模型收敛;引入多通道映射提取更加丰富的特征,使用多层3×3等小卷积核代替单层9×9等大卷积核,更加有效地利用特征,增强模型的超分辨率重构效果。结果 MCSR迭代4×106次即可收敛,在Set5与Set14数据集上边长放大3倍后的平均峰值信噪比分别是32.84 dB和29.28 dB,与SRCNN相比提升显著。结论 MCSR收敛速度更快,并且可以生成轮廓清晰的高分辨率图像,超分辨率效果更加优秀。  相似文献   
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