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Background  

For many microbial processes, the complexity of the metabolisms and the responses to transient and realistic conditions are difficult to capture in mechanistic models. The cells seem to have an innate intelligence that enables them to respond optimally to environmental changes. Some "intelligent" models have therefore been proposed and compared with a mechanistic model for fed-batch cultures of Ralstonia eutropha.  相似文献   

3.
In this study, artificial intelligence techniques—specifically artificial neural networks (ANNs) in combination with fuzzy logic (neurofuzzy logic) or with genetic algorithms (ANNs–GA)—have been employed, as modeling tools, to get insight, to predict and to optimize the effect of several independent factors on four growth parameters during Pistacia vera micropropagation. Twenty-six media ingredients, including mineral ions (or salts), glycine, vitamins and plant growth regulators (PGRs) at different concentrations, were used as inputs and four growth parameters: proliferation rate, shoot length, total and healthy fresh weight as outputs on the models. The IF-THEN rules from neurofuzzy logic models have allowed discovering the positive (BAP, nicotinic-acid and pyridoxine-HCl) and negative (NO3 ?, Mg2+, Ag+ and gluconate?) effects on the growth parameters and the fundamental role of BAP over all of them. Also, ANNs–GA technology has permitted to estimate the best combination of media ingredients to simultaneously maximize the four parameters of growth: 4.4 new shoots per explant; 28.7 mm length; 1.1 and 0.53 g total and healthy fresh weight, respectively, minimizing physiological disorders. In our opinion, the information obtained in this study is extremely useful to improve the massive multiplication of pistachio plant, in particular, but also demonstrate the ability of artificial intelligence technology to design plant tissue culture media with predictable and tailorable characteristics.  相似文献   

4.
When conducting a statistical analysis of data from a designed experiment, an investigator is often interested in confidence intervals for contrasts of the fixed effects. If the analysis involves a mixed linear model, exact confidence intervals for contrasts of the fixed effects are not always available. In such cases, confidence intervals with approximate coverage probabilities must be used. As will be shown, this problem may be generalized to that of constructing a confidence interval for the parameter μ, where X is a normal random variable with mean μ and variance ∑ aqθq, where a1…,aQ are known constants, Uq = nqSq is a chi-squared random variable with nq degrees of freedom, for each q = 1,…, Q, and X,U1,…, UQ are mutually independent. In this paper, we consider the case where Q = 3 and a3 ≤0.  相似文献   

5.
The model considered in this article is the two-factor nested unbalanced variance component model: for p = 1, 2, …, P; q = 1, 2, …, Qp; and r = 1, 2, …, Rpq. The random variables Ypqr are observable. The constant μ is an unknown parameter, and Ap, Bpq and Cpqr are (unobservable) normal and independently distributed random variables with zero means and finite variances σ2A, σ2B, and σ2C, respectively. Approximate confidence intervals on ?A and ?B using unweighted means are derived, where The performance of these approximate confidence intervals are evaluated using computer simulation. The simulated results indicate that these proposed confidence intervals perform satisfactorily and can be used in applied problems.  相似文献   

6.
K. H. Gardner  J. Blackwell 《Biopolymers》1974,13(10):1975-2001
Native cellulose has been shown to consist of a crystalline array of parallel chains, based on the X-ray diffraction data for specimens from the sea alga Valonia ventricosa. The unit cell is monoclinic with dimensions a = 16.34 Å, b = 15.72 Å, c = 10.38 Å (fiber axis), and β = 97.0°. The space group is P21 and the cell contains disaccharide segments of eight chains. Models containing chains with the same sense (parallel) or alternating sense (antiparallel) were refined against the intensity data using rigidbody least squares procedures. The results show a preference for a parallel chain structure with specific chain polarity with respect to the c axis. The refinement places the ? CH2OH side chains approximately 20′ from the so-called tg conformation, with a result that an 02′? H…06 intramolecular bond is formed. The structure also contains an 03? H…05′ intramolecular bond and an 06? H…03 intermolecular bond along the a axis. All these bonds lie in the 020 planes, and the structure is an array of hydrogen-bonded sheets. A major consequence of this work is that regular chain folding can be ruled out and cellulose is seen as extended chain polymer single crystals.  相似文献   

7.
The significance of single flower visits by pollinators on the reproductive success of the Scotch broom, Cytisus scoparius, with explosive flowers was investigated. Unexploded flowers (intact flowers) produced no fruit, implying that autonomous selfing and apomixis do not occur and that the explosion of flowers by insects is necessary for the fertilization of flowers. The fruit set in the natural condition was intermediate between that in artificial selfing or exploding and that in artificial outcrossing. Seed set and the ratio of seeds to ovules did not differ significantly between the natural condition and artificial outcrossing. The fruit set by a single flower visit from Apis mellifera was similar to natural conditions. Apis mellifera was the most frequent visitor and the number of flowers tripped open per hour was the highest among all the flower visitors. Approximately 75% of pollen on a flower disappeared in a single flower visit by A.mellifera. The small amount of pollen remaining on already-exploded flowers appears to be the reason why A.mellifera do not frequently visit already-exploded flowers. The higher seed set by outcrossing was believed to contribute to the seed set in both natural conditions and single flower visits by A.mellifera, and did not differ between them. Therefore, at least in Japan, A.mellifera appears to be the most important pollinator for C.scoparius, resulting in a high outcrossing rate with each single flower visit.  相似文献   

8.
The Normalized Difference Vegetation Index (NDVI) or greenness index, based on the Advanced Very High Resolution Radiometer (AVHRR) aboard the NOAA-7 satellite, has been widely interpreted as a measure of regional to global vegetation patterns. This study provides the first rigorous, quantitative evaluation of global relationships between the NDVI and geographically representative vegetation data-bases, including field metabolic measurements and carbon-balance results from global simulation models. Geographic reliability of the NDVI is judged by comparing NDVI values for different surface types with a general global trend and by statistical analysis of relationships to biomass amounts, net and gross primary productivity, and actual evapotranspiration. NDVI data appear to be relatively reliable predictors of primary productivity except in areas of complex terrain, for seasonal values at high latitudes, and in extreme deserts. The strength of the NDVI-productivity relationship seems comparable to that of earlier climate-based productivity models. Little consistent relationship was found, across different vegetation types, between NDVI and biomass amounts or net biospheric CO2 flux.Abbreviations AET= Actual Evapotranspiration - AVHRR= Advanced Very High Resolution Radiometer - GPP= Gross Primary Production - GVI= Global Vegetation Index - NDVI= Normalized Difference Vegetation Index - NPP= Net Primary Production  相似文献   

9.
The situation is considered where the multivariate distribution of certain variables X1, X2, …, Xp is changing with time in a population because natural selection related to the X's is taking place. It is assumed that random samples taken from the population at times t1, t2, …, ts are available and it is desirable to estimate the fitness function wt(x1, x2,…,xp) which shows how the number of individuals with Xi = xi, i = 1, 2, …, p at time t is related to the number of individuals with the same X values at time zero. Tests for population changes are discussed and indices of the selection on the population dispersion and the population mean are proposed. The situation with a multivariate normal distribution is considered as a special case. A maximum likelihood method that can be applied with any form of population distribution is proposed for estimating wt. The methods discussed in the paper are illustrated with data on four dimensions of male Egyptian skulls covering a time span from about 4500 B.C. to about 300 A.D. In this case there seems to have been very little selection on the population dispersion but considerable selection on means.  相似文献   

10.

目的 通过考察医务人员工作倦怠与特质情绪智力的相关关系,为探索改善医务人员工作倦怠状况的方法提供依据。方法 采用随机抽样的方式对552名医务人员进行工作倦怠和特质情绪智力问卷的调查。结果 (1)工作倦怠与特质情绪智力负性相关关系显著;(2)总体上,特质情绪智力对工作倦怠具有一定的负向预测作用。结论 可以通过对医务人员特质情绪智力的培养改善其工作倦怠感,培训方案的设计要注意整体性和全面性。

  相似文献   

11.
In just a few years, the Asian fly Drosophila suzukii has invaded several continents and has become a very serious pest of many fruit crops worldwide. Current control methods rely on chemical insecticides or expensive and labour‐intensive cultural practices. Classical biological control through the introduction of Asian parasitoids that have co‐evolved with the pest may provide a sustainable solution on condition that they are sufficiently specific to avoid non‐target effects on local biodiversity. Here, we present the first study on the development of three larval parasitoids from China and Japan, the Braconidae Asobara japonica and the Figitidae Leptopilina japonica and Ganaspis sp., on D. suzukii. The Asian parasitoids were compared with Leptopilina heterotoma, a common parasitoid of several Drosophilidae worldwide. The three Asian species were successfully reared on D. suzukii larvae in both, blueberry and artificial diet, in contrast to L. heterotoma whose eggs and larvae were encapsulated by the host larvae. All parasitoids were able to oviposit one day after emergence. Asobara japonica laid as many eggs in larvae feeding in blueberry as in artificial diet, whereas L. heterotoma oviposited more in larvae on the artificial diet and the Asian Figitidae oviposited more in larvae feeding on blueberry. Ganaspis sp. laid very few eggs in larvae in the artificial diet, suggesting that it may be specialized in Drosophila species living in fresh fruits. These data will be used for the development of a host range testing to assess the suitability of Asian parasitoids as biological control agents in invaded regions.  相似文献   

12.
《Plant Ecology & Diversity》2013,6(2-3):295-300
We reply to Webber et al. (2011 Webber, BL, Born, C, Conn, BJ, Hadiah, JT and Zalamea, P-C. 2011. What is in a name? That which we call Cecropia peltata by any other name would be as invasive?. Plant Ecology & Diversity, 3: 241245.  [Google Scholar]). Our study, Sheil and Padmanaba (2011 Sheil, D and Padmanaba, M. 2011. Innocent invaders? A preliminary assessment of Cecropia, an American tree, in Java. Plant Ecology & Diversity, 3: 231240.  [Google Scholar]), was a preliminary assessment of the alien Neotropical tree Cecropia around Bogor, West Java, Indonesia. We highlighted the need for low-cost assessment approaches for addressing alien species and considered what might be achieved by local actors with limited resources. We successfully characterised the local distribution of Cecropia and identified, addressed and illustrated various concerns. Based on these results we asked how such studies might be useful and how they could be improved. Webber et al. criticise our study but fail to engage with its goals. Certainly, low-input local approaches lack the sophistication and rigour of larger international efforts, but such comparisons are unhelpful. Aside from a number of misunderstandings, we find Webber et al.’s principal arguments overstated, and unsupported by published information. The evidence that Cecropia causes harm is unconvincing; species-level identification is overemphasised; and the insistence on completing detailed research before considering management options is problematic. We offer some positive conclusions and repeat our plea for the development of effective low-input methods for evaluating and addressing naturalised organisms.  相似文献   

13.
This is a review of Patrick Meier’s 2015 book, Digital Humanitarians: How Big Data Is Changing the Face of Humanitarian Response. The book explores the role of technologies such as high-resolution satellite imagery, online social media, drones, and artificial intelligence in humanitarian responses during disasters such as the 2010 Haiti earthquake. In this analysis, the book is examined using a humanitarian health ethics perspective.  相似文献   

14.
The IR data for the R1 CO-O-CHR2-CO-NHR3 derivatives are interpreted in terms of a H…π interaction involving the N? H bond and the π orbitals of the ester function and giving rise to a high ν(C?O) frequency and a low ν frequency. The resulting molecular conformation corresponds to the angular values ? # ?90°, ψ # 0°. The H…π interaction in MeCO-L-Lac-NHMe is highly destabilized by water and aprotic solvents but is retained in methanol. Considering the high ν(C?O) ester or amide frequency of the middle function in β-folded depsipeptide or peptide sequences, it may be supposed that the residue indexed i + 2 in β turns experiences a H…π interaction which has a stabilizing effect on β turns. Some examples concerning valinomycin and some model compounds are discussed.  相似文献   

15.
Summary Resolution of a tertiary allylic terpene alcohol (linalool) employed in flavor and fragrance applications was achieved via biocatalytic hydrolysis of its acetate ester using the carboxyl ester hydrolase activity of lyophilized bacterial cells. Several strains of the genera Rhodococcus, Nocardia, Arthrobacter and Mycobacterium were found to be active. In general, the enantioselectivity was low; only with Rhodococcus ruber SM 1792 (S)-linalool was obtained in 58% e.e. (E-value ~5).  相似文献   

16.
目的:探讨应用人工智能系统对青光眼患者的检出率、筛查的时间成本和经济成本,总结分析其应用于青光眼筛查的优越性与可行性。方法:回顾性研究。收集2019-2020年使用腾讯觅影眼底照片辅助诊断系统进行青光眼筛查的53700例受检者,2012-2018年使用北京同仁医院眼科研究所远程眼科会诊中心的493221例患者,邯郸眼病研究中接受基础眼病筛查的6716名受检者资料。评价人工智能筛查系统对青光眼的检出率,并采用Pearson x~2检验,比较人工智能筛查系统与远程阅片平台、基础眼病筛查对于青光眼检出率的差异,并对三种筛查方式的时间成本和经济成本进行比较分析。结果:临床应用表明,其成本效益的可靠数据及主要指标:检出率、x~2值、时间成本、经济成本等效益显著。人工智能筛查系统对青光眼的检出率为6.56%,远程眼科会诊平台的检出率为2.78%,邯郸眼病研究的检出率为1.70%,人工智能筛查系统与另外两种模式对青光眼诊断检出率的差异有统计学意义(P0.05)。而且使用人工智能筛查系统的患者其医疗时间成本和经济成本花费较低。结论:可行性分析表明,相较于远程眼科会诊平台和基础眼病筛查,人工智能筛查系统对青光眼的检出率较高,同时患者的时间成本和经济成本都得到了大幅度降低,这为青光眼筛查提供了一种有效而快捷的方式,值得临床推广。  相似文献   

17.
Molecular variants of vitamin B12, siderophores, and glycans occur. To take up variant forms, bacteria may express an array of receptors. The gut microbe Bacteroides thetaiotaomicron has three different receptors to take up variants of vitamin B12 and 88 receptors to take up various glycans. The design of receptor arrays reflects key processes that shape cellular evolution. Competition may focus each species on a subset of the available nutrient diversity. Some gut bacteria can take up only a narrow range of carbohydrates, whereas species such as B. thetaiotaomicron can digest many different complex glycans. Comparison of different nutrients, habitats, and genomes provides opportunity to test hypotheses about the breadth of receptor arrays. Another important process concerns fluctuations in nutrient availability. Such fluctuations enhance the value of cellular sensors, which gain information about environmental availability and adjust receptor deployment. Bacteria often adjust receptor expression in response to fluctuations of particular carbohydrate food sources. Some species may adjust expression of uptake receptors for specific siderophores. How do cells use sensor information to control the response to fluctuations? This question about regulatory wiring relates to problems that arise in control theory and artificial intelligence. Control theory clarifies how to analyze environmental fluctuations in relation to the design of sensors and response systems. Recent advances in deep learning studies of artificial intelligence focus on the architecture of regulatory wiring and the ways in which complex control networks represent and classify environmental states. I emphasize the similar design problems that arise in cellular evolution, control theory, and artificial intelligence. I connect those broad conceptual aspects to many testable hypotheses for bacterial uptake of vitamin B12, siderophores, and glycans.  相似文献   

18.
…adaptation to bipedal locomotion decreased the size of the bony birth-canal at the same time that the exigencies of tool use selected for larger brains. This obstetrical dilemma was solved by delivery of the fetus at a much earlier stage of development. (Washburn1) …there can be no doubt that many of the obstetrical problems of Mrs. H. Sapiens are due to the combination of a narrower pelvis and a bigger head in the species. (Krogman2)  相似文献   

19.
A concept of the live unit as an automatic regulation system with a few admissible states areas in the space of states is considered. Energetic profit of oscillatory behavior consisting in the consecutive transitions of system from one admissible states area to another is shown. It is stated, that external disturbances cause the energy consumption of oscillatory system to decrease. On the basis of this concept and some neurophysiological data, the live energy-consuming nonlinear three-state neuron model is proposed and the existence of energy optimal generation frequency v opt is proved. For the realization of tendency to v opt the optimal learning rule is proposed, which provides unsupervised learning and interlinked short-term and long-term memories with forgetting. The model proposed explains the genesis of neural network, is promising in the sense of network self-organization and allows to solve the problem of internal activity in the researches on artificial intelligence.  相似文献   

20.
目的 运用知识管理的理念和方法,探讨切合实际应用的临床决策支持知识库概念模型,使医院能够通过知识管理提升其核心竞争力。方法 收集国内外相关资料,系统化研究及分析具有人工智能的临床决策支持知识库的框架。结果 实施医院知识管理的关键就是必须建立一个动态的,并具有自我学习能力的临床决策支持知识库,该知识库不仅需要通过医院信息系统收集传统的医学知识,而且需要建立用于临床指南等的标准医学知识收集的引擎和隐性知识转化模型,并嵌入智能化工具,通过知识库的自我学习功能,保证其动态更新和智能化的临床决策支持能力。结论 医院知识库创建过程实质也是医院价值的创造过程,智能化的临床决策支持知识库开发不仅涉及知识的收集和处理, 还包括知识的表达,人工智能技术的嵌入和各种规则、条件及分类方法等的应用,有待进一步研究。  相似文献   

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