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41.
Mark Olokotum Marc Troussellier Arthur Escalas Sahima Hamlaoui William Okello Ronald Semyalo Jean-François Humbert Cécile Bernard 《Journal of Great Lakes research》2021,47(4):985-996
Eutrophication of Lake Victoria led to changes in its phytoplankton communities. However, different levels of eutrophication exist in the open lake and the bays, and between embayments. This study utilized spatial and temporal sampling of Napoleon Gulf and Murchison Bay, exhibiting different trophic conditions. Over one year, we investigated phytoplankton biomass, richness, diversity and dissimilarity, and related the dynamics of the dominant species to the limnological and climatic conditions. The results confirmed that Napoleon Gulf and Murchison Bay showed large differences in eutrophication status, with lower nutrient concentrations in Napoleon Gulf than in Murchison Bay, where a strong gradient was observed from inshore to offshore areas. These nutrient dynamics resulted in a 4 to 10 fold higher chlorophyll-a in Murchison Bay than in Napoleon Gulf. From the embayments, 135 phytoplankton taxa were recorded with no significant differences in alpha diversity. However, high dissimilarity in community structure was observed in beta diversity, mostly due to a turnover among the dominant toxigenic species. Thus, from a similar species pool, there was a shift in the dominant toxigenic cyanobacteria from Microcystis flos-aquae and M. aeruginosa in Murchison Bay, Dolichospermum circinale and Planktolyngbya circumcreta in Napoleon Gulf to D. circinale in the offshore stations. These cyanobacteria are toxigenic taxa with known health hazards. Using partial least square models, we showed that both climatic variables (e.g. wind, solar radiation) and levels of inorganic dissolved nutrients (e.g. SRP, NO3–, and NH4+) are the main drivers of differences and dominance in cyanobacteria communities in northern Lake Victoria. 相似文献
42.
We present a filter-and-refine method to speed up nearest neighbor searches with the Kullback–Leibler divergence for multivariate
Gaussians. This combination of features and similarity estimation is of special interest in the field of automatic music recommendation
as it is widely used to compute music similarity. However, the non-vectorial features and a non-metric divergence make using
it with large corpora difficult, as standard indexing algorithms can not be used. This paper proposes a method for fast nearest
neighbor retrieval in large databases which relies on the above approach. In its core the method rescales the divergence and
uses a modified FastMap implementation to speed up nearest-neighbor queries. Overall the method accelerates the search for
similar music pieces by a factor of 10–30 and yields high recall values of 95–99% compared to a standard linear search. 相似文献
43.
Ming-Hui Yang Yi-Ming Arthur Chen Shan-Chen Tu Pei-Ling Chi Kuo-Pin Chuang Chin-Chuan Chang Chiang-Hsuan Lee Yi-Ling Chen Che-Hsin Lee Cheng-Hui Yuan Yu-Chang Tyan 《International journal of molecular sciences》2021,22(6)
Glycine N-methyltransferase (GNMT) regulates S-adenosylmethionine (SAMe), a methyl donor in methylation. Over-expressed SAMe may cause neurogenic capacity reduction and memory impairment. GNMT knockout mice (GNMT-KO) was applied as an experimental model to evaluate its effect on neurons. In this study, proteins from brain tissues were studied using proteomic approaches, Haemotoxylin and Eosin staining, immunohistochemistry, Western blotting, and ingenuity pathway analysis. The expression of Receptor-interacting protein 1(RIPK1) and Caspase 3 were up-regulated and activity-dependent neuroprotective protein (ADNP) was down-regulated in GNMT-KO mice regardless of the age. Besides, proteins related to neuropathology, such as excitatory amino acid transporter 2, calcium/calmodulin-dependent protein kinase type II subunit alpha, and Cu-Zn superoxide dismutase were found only in the group of aged wild-type mice; 4-aminobutyrate amino transferase, limbic system-associated membrane protein, sodium- and chloride-dependent GABA transporter 3 and ProSAAS were found only in the group of young GNMT-KO mice and are related to function of neurons; serum albumin and Rho GDP dissociation inhibitor 1 were found only in the group of aged GNMT-KO mice and are connected to neurodegenerative disorders. With proteomic analyses, a pathway involving Gonadotropin-releasing hormone (GnRH) signal was found to be associated with aging. The GnRH pathway could provide additional information on the mechanism of aging and non-aging related neurodegeneration, and these protein markers may be served in developing future therapeutic treatments to ameliorate aging and prevent diseases. 相似文献
44.
A mathematical model was used to investigate the effects of electrical inhomogeneities introduced by the intracavitary blood mass and the lungs on the apparent location and magnitude of a current dipole source representing local activity in the myocardium. Radial and tangential current source moments were considered, and lung conductivity was taken as a variable parameter. Both the blood mass and the lungs cause a current source to appear closer to the heart center than it actually is. The effect increases as the source moves away from the endocardial surface, and maximum displacement is estimated to be of the order of 1 cm. The net effect of the inhomogeneities is to increase the magnitude of the radial component of a source dipole while diminishing its tangential component. These effects depend on source location. 相似文献
45.
Microstructural characterization of a high-Al2 O3 substrate containing cofired thick-film tungsten metallization, with particular emphasis on the metal/ceramic interface, was conducted. The substrate contained tabular Al2 O3 grains surrounded by a continuous calcium magnesium aluminum silicate glass containing particles of monoclinic ZrO2 and reduced rutile (TiO2- x ). The metal/ceramic adhesion was caused by mechanical interlocking between the W and Al2 O3 grains by the glass phase which penetrated the porous W layers during sintering; there was no interfacial reaction or diffusion zone. The mechanical properties of the W metallization did not limit interfacial strength. Heat treatments of the substrate at 1400 K in air and under vacuum resulted in the devitrification of the intergranular glass. The most abundant devitrification product was anorthite (CaAl2 Si2 O8 ), accompanied by magnesium aluminate titanate, magnesium aluminate spinel, α-cristobalite (SiO2 ), and α-cordierite (Mg2 Al4 Si5 O18 ). In addition, small rutile particles precipitated within the Al2 O3 grains. 相似文献
46.
Arthur K. Doolittle 《应用聚合物科学杂志》1979,24(5):1329-1340
Our volume–entropy–energy (VSE) equation of state for liquids, first proposed in 1973 for use with low molecular weight homogeneous liquids, is here applied for the first time to a high molecular weight liquid that is heterogeneous in molecular weight, namely, a molten polymer. Four thermo-dynamic quantities, T, s, cp, and ε are calculated over the range of 600–725 K at ambient pressure and are compared with experimental values, with excellent results. The grand average of the standard percentage errors (S.P.E.) for the 24 points is 0.1100%. 相似文献
47.
Hyoun-Ee Kim Arthur J. Moorhead Doh-Hyung Riu Dong-Han Lee 《Journal of the American Ceramic Society》1995,78(6):1708-1710
Sintered α-SiC was exposed, for times up to 2 h, to a flowing wet H2 atmosphere ( P H2 O = 1 × 10-4 MPa) at temperatures of 1300°, 1400°, and 1500°C. The effect of such conditions on the reliability of the ceramic was estimated by comparing the Weibull modulus of the groups of specimens, tested in four-point flexure, before and after exposure. The Weibull modulus of as-polished specimens was 6.7, indicating a wide variation in room-temperature flexural strength. The Weibull modulus was increased to 14.2 by the heat treatment for 2 h in wet H2 at 1400°C. The average strength was also improved from 347 to 446 MPa by such exposure. Heat treatment at 1300° and 1500°C also improved the reliability of the material, as indicated by increases in the Weibull modulus, but to less a degree than did exposure at 1400°C. The increases in reliability and average strength were attributed to the blunting of surface flaws by the formation of a thin SiO2 layer on the sample surface. 相似文献
48.
Cotton ha been dyed with reactive dyes by both wet-on-wet (WOW) and wet-on-dry (WOD) cold pad-batch processes, and by conventional exhaust methods. The colour yields, in terms of the Kubelka-Munk values as a function of the amount of fixed dye, showed that the WOW method required less fixed dye to produce a given depth of shade than the other methods. It is proposed that the higher colour yields are a consequence of limited dye penetration into the cotton fibre. Compared with exhaust dyeings, WOW and WOD dyeings were clearly ring dyed but, unfortunately, no definitive difference in the degree of dye penetration into the cotton fibres was found despite their colour yield differences. Although ring dyeings often have inferior fastness properties, the WOW dyeings were of equal or slightly superior fastness to repeated washing and to normal daylight in comparison with the other dyeings 相似文献
49.
In-Ho Jung Sergei Decterov Arthur D. Pelton 《Journal of the American Ceramic Society》2005,88(7):1921-1928
A complete critical evaluation and thermodynamic modeling of the phase diagrams and thermodynamic properties of the MgO–Al2 O3 –CrO–Cr2 O3 system at 1 bar total pressure are presented. Optimized equations for the thermodynamic properties of all phases are obtained which reproduce all available thermodynamic and phase equilibrium data within experimental error limits from 25°C to above the liquidus temperatures at all compositions and oxygen partial pressures. The optimized thermodynamic properties and phase diagrams are believed to be the best estimates presently available. The database of the model parameters can be used along with software for Gibbs energy minimization in order to calculate any type of phase diagram section. 相似文献
50.
Zhou D Lagoja IM Rozenski J Busson R Van Aerschot A Herdewijn P 《Chembiochem : a European journal of chemical biology》2005,6(12):2298-2304
Oligonucleotides that contain up to three aminopropyl nucleoside analogues have been synthesized. Dimers of aminopropyl adenine and thymidine were prepared and used as building blocks by applying phosphoramidite chemistry. Both R and S isomers of the aminopropyl nucleosides were used. This incorporation led to a reduction of thermal stability of double-stranded DNA. Furthermore, the (R)-adenine analogue, which yielded (S)-APNA, can be considered as a candidate for universal base pairing. 相似文献