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41.
In this paper we compare some of the objective quality measures with subjective, in several HDTV formats, to be able to grade the quality of the objective measures. Also, comparison of objective and subjective measures between progressive and interlaced video signal will be presented to determine which scanning emission format is better, even if it has different resolution format. Several objective quality measures will be tested, to examine the correlation with the subjective test, using various performance measures. 相似文献
42.
Claudia Guillaume Leandro Ravetti Sonja Gwyn 《Journal of the American Oil Chemists' Society》2010,87(3):247-254
Frost is one of the most important weather related hazards for the Australian olive industry and it has caused significant
economic losses during the last decade. Its impact on oil quality was significant in 2006 with more than 20% of Australian
oil of that year being affected to some degree. Early frosts will normally affect the fruit leading to significant changes
in the chemical and organoleptic characteristics of the oils. The aim of this work was to study the effect of freeze damage
on the phenolic composition and quality parameters of oils from three different varieties: Frantoio, Barnea and Picual. Quality
chemical parameters showed significant differences in oils produced from fruit that was frozen for 2 and 4 weeks. Those chemical
parameters were not significantly different in the oil produced from fruit immediately after being frosted. Nonetheless, the
sensorial profile and the polyphenols showed significant changes even with oils produced within a short time after the freezing
event. Those changes became more evident with the oils produced at increasing time from the moment of fruit freezing. 相似文献
43.
The impact of gamma-irradiation on 5′-nucleotides and on the free amino acids tyrosine and phenylalanine in fresh mushrooms was studied. After irradiation the samples were freeze-dried to avoid enzyme induced chemical changes. Three 5′-nucleotides could be detected using HPLC–UV and LC–ESI-MS: adenosine 5′-monophosphate (AMP), guanosine 5′-monophosphate (GMP) and guanosine 5′-diphosphate (GDP). Irradiation significantly reduced (p = 0.05) the GDP concentration (22%). AMP showed a marked reduction (46%) only at 5 kGy. GMP, tyrosine, and phenylalanine were not affected by gamma-irradiation. 相似文献
44.
Sonja Berg Melanie J. Leng Christopher P. Kendrick Holger Cremer Bernd Wagner 《SILICON》2013,5(1):19-34
Organic carbon occluded in diatom silica is assumed to be protected from degradation in the sediment. δ13C from diatom carbon (δ13C(diatom)) therefore potentially provides a signal of conditions during diatom growth. However, there have been few studies based on δ13C(diatom). Numerous variables can influence δ13C of organic matter in the marine environment (e.g., salinity, light, nutrient and CO2 availability). Here we compare δ13C(diatom) and δ13C(TOC) from three sediment records from individual marine inlets (Rauer Group, East Antarctica) to (i) investigate deviations between δ13C(diatom) and δ13C(TOC), to (ii) identify biological and environmental controls on δ13C(diatom) and δ13C(TOC), and to (iii) discuss δ13C(diatom) as a proxy for environmental and climate reconstructions. The records show individual δ13C(diatom) and δ13C(TOC) characteristics, which indicates that δ13C is not primarily controlled by regional climate or atmospheric CO2 concentration. Since the inlets vary in water depths offsets in δ13C are probably related to differences in water column stratification and mixing, which influences redistribution of nutrients and carbon within each inlet. In our dataset changes in δ13C(diatom) and δ13C(TOC) could not unequivocally be ascribed to changes in diatom species composition, either because the variation in δ13C(diatom) between the observed species is too small or because other environmental controls are more dominant. Records from the Southern Ocean show depleted δ13C(diatom) values (1–4 ‰) during glacial times compared to the Holocene. Although climate variability throughout the Holocene is low compared to glacial/interglacial variability, we find variability in δ13C(diatom), which is in the same order of magnitude. δ13C of organic matter produced in the costal marine environment seems to be much more sensitive to environmental changes than open ocean sites and δ13C is of strongly local nature. 相似文献
45.
Back Cover: Insight into the Interactions between Novel Coumarin Derivatives and Human A3 Adenosine Receptors (ChemMedChem 10/2014) 下载免费PDF全文
46.
Saša Piskernik Anja Klančnik Charlotte Tandrup Riedel Lone Brøndsted Sonja Smole Možina 《Food Control》2011,22(5):718-724
Nowadays it is essential to test new preservation and decontamination procedures using naturally occurring chemicals against important pathogenic bacteria in meat. We tested the antimicrobial effect of rosemary extracts and the bacteriocin nisin against Campylobacter jejuni at a low storage temperature (8 °C) with or without short-term pre-freezing. The antimicrobial effect of rosemary extract was four times greater in laboratory media than in chicken meat juice. Furthermore, low temperature storage conditions prolonged the survival of C. jejuni in chicken meat juice. Nisin, with an approximately 1.0 log reduction was neither effective alone nor in combination with the extract. Pre-freezing with plant extract addition proved to be effective treatment by more than 3.0 log reduction in 48 h. The results in chicken meat food model again showed the synergistic effect of freezing and plant extract antimicrobial activity. As the combination of pre-freezing and plant extract treatment reduced the cell number by more than 2.0 log reduction, studies should be conducted to further evaluate this promising treatment for Campylobacter reduction in the poultry meat supply. 相似文献
47.
Bioaugmentation is an attractive mechanism for reducing recalcitrant pollutants in sediments, especially if this technology could be applied in situ. To examine the potential effectiveness of a bioaugmentation strategy for PCB contamination, PCB dehalorespiring populations were inoculated into Baltimore Harbor sediment microcosms. A culture containing the two most predominant indigenous PCB dehalorespiring microorganisms and a culture containing a strain with a rare ortho dechlorination activity and a non-indigenous strain that attacks double-flanked chlorines, were inoculated into sediment microcosms amended with 2,2′,3,5,5′,6-hexachlorobiphenyl (PCB 151) and Aroclor 1260. Although we observed a similar reduction in the concentration of PCB 151 in all microcosms at day 300, a reduced lag time for dechlorination activity was observed only in the bioaugmented microcosms and the pattern of dechlorination was altered depending on the initial combination of microorganisms added. Dechlorination of Aroclor 1260 was most extensive when dehalorespiring microorganisms were added to sediment. Overall numbers of dehalorespiring microorganisms in both bioaugmented and non-bioaugmented microcosms increased 100- and 1000-fold with PCB 151 and Aroclor 1260, respectively, and they were sustained for the full 300 days of the experiments. The ability of bioaugmentation to redirect dechlorination reactions in the sediment microcosms indicates that the inoculated PCB dehalorespiring microorganisms effectively competed with the indigenous microbial populations and cooperatively enhanced or altered the specific pathways of PCB dechlorination. These observations indicate that bioaugmentation with PCB dehalorespiring microorganisms is a potentially tractable approach for in situ treatment of PCB impacted sites. 相似文献
48.
Unitary events in multiple single-neuron spiking activity: I. Detection and significance. 总被引:1,自引:0,他引:1
It has been proposed that cortical neurons organize dynamically into functional groups (cell assemblies) by the temporal structure of their joint spiking activity. Here, we describe a novel method to detect conspicuous patterns of coincident joint spike activity among simultaneously recorded single neurons. The statistical significance of these unitary events of coincident joint spike activity is evaluated by the joint-surprise. The method is tested and calibrated on the basis of simulated, stationary spike trains of independently firing neurons, into which coincident joint spike events were inserted under controlled conditions. The sensitivity and specificity of the method are investigated for their dependence on physiological parameters (firing rate, coincidence precision, coincidence pattern complexity) and temporal resolution of the analysis. In the companion article in this issue, we describe an extension of the method, designed to deal with nonstationary firing rates. 相似文献
49.
We describe the hydrolysis of phosphatidylinositol 4,5-bisphosphate by a particulate rat brain preparation in the presence
of the cationic detergent, cetrimide. The optimum cetrimide concentration was in the range 0.2–0.4 mg/ml; at higher or lower
concentrations, the reaction rate diminished abruptly, suggesting that the electrical charge density of the micelle is critical
for enzymatic attack. In other respects, such as its partial requirement for Ca++ and its pH optimum of about 7.0, the particulate enzyme seems similar to soluble preparations which have been reported previously.
Interestingly, the particulate preparation could be stimulated about fourfold by a soluble brain extract in the presence of
1 mM guanosine triphosphate, confirming that the enzyme is the catalytic subunit in a membrane-bound signal-transduction system. 相似文献
50.
Categorical data occur in a wide range of statistical applications. If the data are observed in matched pairs, it is often of interest to examine the differences between the responses. The focus is on tests of axial symmetry in two-way tables. A commonly used procedure is the Bowker test which is a generalization of the McNemar test. The test decision is based on a chi-squared approximation which might not be adequate, for example if the table is sparse. Therefore, modifications of the test statistic have been discussed. A test of symmetry based on Bowker's test and Markov Chain Monte Carlo methods is proposed. A simulation study is carried out to determine and compare the performances of the simulation test, the Bowker test and two modifications. 相似文献