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1.
2.
This paper gives a quantitative analysis on the non-CO2 emissions related to energy demand, energy activities and land use change of six scenarios with different development pattern in 2030 and 2050 based on IPAC emission model. The various mitigation technologies and policies are assessed to understand the corresponding non-CO2 emission reduction effect. The research shows that the future non-CO2 emissions of China will grow along with increasing energy demand, in which thermal power and transportation will be the major emission and mitigation sectors. During the cause of future social and economic development, the control and mitigation of non-CO2 emissions is a problem as challenging and pressing as that of CO2 emissions.This study indicates that the energy efficiency improvement, renewable energy, advanced nuclear power generation, fuel cell, coal-fired combined cycle, clean coal and motor vehicle emission control technologies will contribute to non-CO2 emissions control and mitigation. 相似文献
3.
A terminal alpha1-3 linked Gal or GalNAc sugar residue is the common structure found in several oligosaccharide antigens, such as blood groups A and B, the xeno-antigen, the Forssman antigen, and the isogloboside 3 (iGb3) glycolipid. The enzymes involved in the addition of this residue display strong amino acid sequence similarities, suggesting a common fold. From a recently solved crystal structure of the bovine alpha3-galactosyltransferase complexed with UDP, homology modeling methods were used to build the four other enzymes of this family in their locked conformation. Nucleotide-sugars, the Mn2+ ion, and oligosaccharide acceptors were docked in the models. Nine different amino acid regions are involved in the substrate binding sites. After geometry optimization of the complexes and analysis of the predicted structures, the basis of the specificities can be rationalized. In the nucleotide-sugar binding site, the specificity between Gal or GalNAc transferase activity is due to the relative size of two clue amino acids. In the acceptor site, the presence of up to three tryptophan residues define the complexity of the oligosaccharide that can be specifically recognized. The modeling study helps in rationalizing the crystallographic data obtained in this family and provides insights on the basis of substrate and donor recognition. 相似文献
4.
It has been argued that spatially explicit population models (SEPMs) cannot provide reliable guidance for conservation biology because of the difficulty of obtaining direct estimates for their demographic and dispersal parameters and because of error propagation. We argue that appropriate model calibration procedures can access additional sources of information, compensating the lack of direct parameter estimates. Our objective is to show how model calibration using population-level data can facilitate the construction of SEPMs that produce reliable predictions for conservation even when direct parameter estimates are inadequate. We constructed a spatially explicit and individual-based population model for the dynamics of brown bears (Ursus arctos) after a reintroduction program in Austria. To calibrate the model we developed a procedure that compared the simulated population dynamics with distinct features of the known population dynamics (=patterns). This procedure detected model parameterizations that did not reproduce the known dynamics. Global sensitivity analysis of the uncalibrated model revealed high uncertainty in most model predictions due to large parameter uncertainties (coefficients of variation CV 0.8). However, the calibrated model yielded predictions with considerably reduced uncertainty (CV 0.2). A pattern or a combination of various patterns that embed information on the entire model dynamics can reduce the uncertainty in model predictions, and the application of different patterns with high information content yields the same model predictions. In contrast, a pattern that does not embed information on the entire population dynamics (e.g., bear observations taken from sub-areas of the study area) does not reduce uncertainty in model predictions. Because population-level data for defining (multiple) patterns are often available, our approach could be applied widely. 相似文献
5.
We analyze the characteristics of front propagation in activity of 1-D neuronal cultures by numerical simulations, using only
excitatory dynamics. Experimental results in 1-D cultures of hippocampal neurons from rats have shown the spontaneous generation
of a slow, low amplitude pulse that precedes a high amplitude, fast pulse that propagates through all the system. Notably,
this transition appears both with and without the presence of functioning inhibitory synapses. In accordance with previous
work, we demonstrate that purely excitatory integrate and fire neurons with depression in the synapses suffice to produce
fast and uniform pulses but cannot explain the appearance of slow, weak pulses. We propose to explain the slow pulses by increasing
the complexity of the neuron model in a purely excitatory network with connectivity as close to the experiments as possible.
This approach allows us to show that spike frequency adaptation is a fundamental ingredient for the initiation process of
the pulse. The introduction of a slow variable that mimics the presence of the slow K
+ channels in the soma and produces spike frequency adaptation increases strongly the persistence of the transient activity
before the emergence of the fast pulse up to temporal and spatial scales comparable with the experiments. Finally, we demonstrate
that proper levels of additive white noisy currents generate such pulses spontaneously, fully reproducing the experimental
results.
Electronic supplementary material
The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
E. Alvarez-LacalleEmail: |
6.
We analysed the molecular diversity of Pterocarpus officinalis, a tree species distributed in Caribbean islands, South and Central America to quantify the genetic variation within island,
to assess the pattern of differentiation and infer levels of gene flow; with the overall goal of defining a strategy of conservation.
Two hundred two individuals of 9 populations were analysed using three chloroplast and six nuclear microsatellite markers.
The observed heterozygosity varied markedly among the populations for nuclear (H
Onuc = 0.20–0.50) and chloroplast microsatellites (H
cp = 0.22–0.68). The continental population from French Guyana showed a higher value of H
Onuc than island populations, and the differences were significant in some cases. The fixation index F
IS ranged from −0.043 to 0.368; a significant heterozygote deficit was detected in 7 populations. The heterozygosity excess
method suggested that two populations in Guadeloupe have undergone a recent bottleneck. Global and pairwise F
ST were high for both nuclear (F
STnuc = 0.29) and chloroplast microsatellites (F
STcp = 0.58). The neighbour-joining tree based on both markers, presented a differentiation pattern that can be explained by the
seed dispersal by flotation and marine stream. The comparison of Bayesian approach and the method based on allelic frequency
demonstrate a very limited number of migrants between populations. 相似文献
7.
Xanthiakos K Simos D Angelidis AS Nychas GJ Koutsoumanis K 《Journal of applied microbiology》2006,100(6):1289-1298
AIMS: The development and validation of a dynamic model for predicting Listeria monocytogenes growth in pasteurized milk stored at both static and dynamic temperature conditions. METHODS AND RESULTS: Growth of inoculated L. monocytogenes in a commercial pasteurized whole milk product was monitored at various isothermal conditions from 1.5 to 16 degrees C. The kinetic parameters of the pathogen were modelled as a function of temperature using a square root type model, which was further validated using data from 92 published growth curves from eight different milk products. Compared to four published models for L. monocytogenes growth, the model developed in this study performed better, with a per cent discrepancy and bias of 49.1 and -1.01%, respectively. The performance of the model in predicting growth at dynamic temperature conditions was evaluated at four different fluctuating temperature scenarios with periodic temperature changes from -2 to 16 degrees C. The prediction of growth at dynamic storage temperature was based on the square root model in conjunction with the differential equations of the Baranyi and Roberts model, which were numerically integrated with respect to time. The per cent relative errors between the observed and the predicted growth of L. monocytogenes were less than 10% for all temperature scenarios tested. CONCLUSIONS: Available models from experiments conducted in laboratory media may result in significant overestimation of L. monocytogenes growth in pasteurized milk because they do not take into account factors such as milk composition (e.g. natural antimicrobial compounds present in milk) and the interactions of the pathogen with the natural microflora. The product-targeted model developed in the present study showed a high performance in predicting growth of L. monocytogenes in pasteurized milk under both static and dynamic temperature conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Temperature fluctuations often occur during the transportation and storage of pasteurized milk. A high performance, dynamic model for the growth of L. monocytogenes can be a useful tool for effective management and optimization of product safety and can lead to more realistic estimations of pasteurized-milk related safety risks. 相似文献
8.
The influence of temperature, pH and media on bacteriocin production by Bacillus sp. P34 was investigated. The effect of temperature and initial pH was evaluated by factorial design and response surface
methodology (RSM). Statistical analysis of results showed that, in the range studied, the two variables have a significant
effect on bacteriocin production. Response-surface data showed maximum antimicrobial activity production at initial pH values
between 6.0 and 8.0 and temperatures between 25 and 37 °C. No relationship between bacterial growth and bacteriocin production
was observed. RSM proved to be a powerful tool in optimizing the production of antimicrobial activity by Bacillus sp. P34. When different media were tested, maximum bacteriocin production was observed in soybean protein-based medium, but
antimicrobial activity was not achieved by cultivation on fish meal, feather meal, whey and grape waste. 相似文献
9.
Single chain fragment variables (ScFvs) have been extensively employed in studying the protein-protein interactions. ScFvs derived from phage display libraries have an additional advantage of being generated against a native antigen, circumventing loss of information on conformational epitopes. In the present study, an attempt has been made to elucidate human chorionic gonadotropin (hCG)-luteinizing hormone (LH) receptor interactions by using a neutral and two inhibitory ScFvs against hCG. The objective was to dock a computationally derived model of these ScFvs onto the crystal structure of hCG and understand the differential roles of the mapped epitopes in hCG-LH receptor interactions. An anti-hCG ScFv, whose epitope was mapped previously using biochemical tools, served as the positive control for assessing the quality of docking analysis. To evaluate the role of specific side chains at the hCG-ScFv interface, binding free energy as well as residue interaction energies of complexes in solution were calculated using molecular mechanics Poisson-Boltzmann/surface area method after performing the molecular dynamic simulations on the selected hCG-ScFv models and validated using biochemical and SPR analysis. The robustness of these calculations was demonstrated by comparing the theoretically determined binding energies with the experimentally obtained kinetic parameters for hCG-ScFv complexes. Superimposition of hCG-ScFv model onto a model of hCG complexed with the 51-266 residues of LH receptor revealed importance of the residues previously thought to be unimportant for hormone binding and response. This analysis provides an alternate tool for understanding the structure-function analysis of ligand-receptor interactions. 相似文献
10.
Jessica R. Hale Kristin L. Laidre Steven J. Jeffries Jonathan J. Scordino Deanna Lynch Ronald J. Jameson M. Tim Tinker 《The Journal of wildlife management》2022,86(4):e22215
Sea otters (Enhydra lutris kenyoni) historically occurred in Washington State, USA, until their local extinction in the early 1900s as a result of the maritime fur trade. Following their extirpation, 59 sea otters were translocated from Amchitka Island, Alaska, USA, to the coast of Washington, with 29 released at Point Grenville in 1969 and 30 released at La Push in 1970. The Washington Department of Fish and Wildlife has outlined 2 main objectives for sea otter recovery: a target population level and a target geographic distribution. Recovery criteria are based on estimates of population abundance, equilibrium abundance (K), and geographic distribution; therefore, estimates of these parameters have important management implications. We compiled available survey data for sea otters in Washington State since their translocation (1977–2019) and fit a Bayesian state-space model to estimate past and current abundance, and equilibrium abundance at multiple spatial scales. We then used forward projections of population dynamics to explore potential scenarios of range recolonization and as the basis of a sensitivity analysis to evaluate the relative influence of movement behavior, frontal wave speed, intrinsic growth, and equilibrium density on future population recovery potential. Our model improves upon previous analyses of sea otter population dynamics in Washington by partitioning and quantifying sources of estimation error to estimate population dynamics, by providing robust estimates of K, and by simulating long-term population growth and range expansion under a range of realistic parameter values. Our model resulted in predictions of population abundance that closely matched observed counts. At the range-wide scale, the population size in our model increased from an average of 21 independent sea otters (95% CI = 13–29) in 1977 to 2,336 independent sea otters (95% CI = 1,467–3,359) in 2019. The average estimated annual growth rate was 12.42% and varied at a sub-regional scale from 6.42–14.92%. The overall estimated mean K density of sea otters in Washington was 1.71 ± 0.90 (SD) independent sea otters/km2 of habitat (1.96 ± 1.04 sea otters/km2, including pups), and estimated densities within the current range correspond on average to 87% of mean sub-regional equilibrium values (range = 66–111%). The projected value of K for all of Washington was 5,287 independent sea otters (95% CI = 2,488–8,086) and 6,080 sea otters including pups (95% CI = 2,861–9,300), assuming a similar range of equilibrium densities in currently un-occupied habitats. Sensitivity analysis of simulations of sea otter population growth and range expansion suggested that mean K density estimates in currently occupied sub-regions had the largest impact on predicted future population growth (r2 = 0.52), followed by the rate of southward range expansion (r2 = 0.26) and the mean K density estimate of currently unoccupied sub-regions to the south of the current range (r2 = 0.04). Our estimates of abundance and sensitivity analysis of simulations of future population abundance and geographic range help determine population status in relation to population recovery targets and identify the most influential parameters affecting future population growth and range expansion for sea otters in Washington State. 相似文献