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1.
Li  Ding  Li  Jiayu 《Plasmonics (Norwell, Mass.)》2019,14(1):263-270

This paper focuses on the effective dielectric constant of water-based plasmonic nanofluid containing SiO2/Ag core/shell nanoparticles (NPs). Two effective models, based on S-parameter retrieval method and Maxwell-Garnett effective medium theory, are employed. The effective dielectric constants predicted by the two effective models are compared and the applicability is evaluated by comparing the reflectance and absorptance. Three influence factors, including volume fraction, core-shell ratio, and size of NPs, are considered. Results show both of the two effective models can predict reliable effective dielectric constants when the volume fraction, size, and core-shell ratio of nanoparticles are 5%, 25 nm, and 4:1 respectively. Only small deviations appear in the resonant region under this condition. With the increase of volume fraction, shell proportion, or size, deviations in the resonant region become larger for both of the two effective models. Therefore, the predicted effective dielectric constants are not suitable for the prediction of optical properties, because the resonant region is the key region of the solar conversion for plasmonic nanofluids. Hence, the parameters of NPs need to be changed to make the effective models applicable. Moreover, the effective model based on S-parameter retrieval can predict more reliable dielectric constant than the effective model based on Maxwell-Garnett theory.

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2.
Summary Acetylene was reduced to ethylene by effective white clover nodules and by fully and partially effective intact nodules, nodule homogenates, and bacteroids of soybeans. Succinate and several amino acids markedly stimulated the reduction by effective soybean bacteroids, but the stimulation was slight with partially effective bacteroids. Acetylene metabolism by effective soybean bacteroids was also enhanced by excretions of in vitro-grown Rhizobium japonicum, excretions of bacteria derived from effective and ineffective nodules, and the soluble fraction from these nodules. Inhibitors of nitrogen fixation were not found in ineffective nodules. Ineffective soybean and white clover nodules and homogenates or isolated bacteria from ineffective soybean nodules did not reduce acetylene. Additions of succinate, amino acids, the soluble fraction of effective nodules, or excretions of effective bacteroids or of in vitro-grown cells of an effective R. japonicum strain did not promote nitrogen fixation by bacterial cells obtained from ineffective soybean nodules.  相似文献   

3.
Effective Population Sizes with Multiple Paternity   总被引:9,自引:0,他引:9       下载免费PDF全文
D. W. Sugg  R. K. Chesser 《Genetics》1994,137(4):1147-1155
While the concept of effective population size is of obvious applicability to many questions in population genetics and conservation biology, its utility has suffered due to a lack of agreement among its various formulations. Often, mathematical formulations for effective sizes apply restrictive assumptions that limit their applicability. Herein, expressions for effective sizes of populations that account for mating tactics, biases in sex ratios, and differential dispersal rates (among other parameters) are developed. Of primary interest is the influence of multiple paternity on the maintenance of genetic variation in a population. In addition to the standard inbreeding and variance effective sizes, intragroup (coancestral) and intergroup effective sizes also are developed. Expressions for effective sizes are developed for the beginning of nonrandom gene exchanges (initial effective sizes), the transition of gene correlations (instantaneous effective sizes), and the steady-state (asymptotic effective size). Results indicate that systems of mating that incorporate more than one male mate per female increase all effective sizes above those expected from polygyny and monogamy. Instantaneous and asymptotic sizes can be expressed relative to the fixation indices. The parameters presented herein can be utilized in models of effective sizes for the study of evolutionary biology and conservation genetics.  相似文献   

4.
We consider a Wright-Fisher model whose population size is an autocorrelated stochastic process. Our interest is in the effects of autocorrelated fluctuations of the population size on the effective size. We define the inbreeding effective size and the variance effective size and show that these effective sizes are the same for this model. In the literature, it is said that the effective size is equal to the harmonic mean of population size when the size fluctuates. We will show, however, that the effective size is not the same as the harmonic mean of population size unless the fluctuations of population size are uncorrelated. The effective size is larger (resp. smaller) than the harmonic mean when the fluctuations of population size are positively (resp. negatively) autocorrelated. Further, we obtain some asymptotic expressions for effective size when the population size is very large and/or the autocorrelation of the fluctuation is very strong.  相似文献   

5.
Effective Sizes for Subdivided Populations   总被引:3,自引:0,他引:3       下载免费PDF全文
Many derivations of effective population sizes have been suggested in the literature; however, few account for the breeding structure and none can readily be expanded to subdivided populations. Breeding structures influence gene correlations through their effects on the number of breeding individuals of each sex, the mean number of progeny per female, and the variance in the number of progeny produced by males and females. Additionally, hierarchical structuring in a population is determined by the number of breeding groups and the migration rates of males and females among such groups. This study derives analytical solutions for effective sizes that can be applied to subdivided populations. Parameters that encapsulate breeding structure and subdivision are utilized to derive the traditional inbreeding and variance effective sizes. Also, it is shown that effective sizes can be determined for any hierarchical level of population structure for which gene correlations can accrue. Derivations of effective sizes for the accumulation of gene correlations within breeding groups (coancestral effective size) and among breeding groups (intergroup effective size) are given. The results converge to traditional, single population measures when similar assumptions are applied. In particular, inbreeding and intergroup effective sizes are shown to be special cases of the coancestral effective size, and intergroup and variance effective sizes will be equal if the population census remains constant. Instantaneous solutions for effective sizes, at any time after gene correlation begins to accrue, are given in terms of traditional F statistics or transition equations. All effective sizes are shown to converge upon a common asymptotic value when breeding tactics and migration rates are constant. The asymptotic effective size can be expressed in terms of the fixation indices and the number of breeding groups; however, the rate of approach to the asymptote is dependent upon dispersal rates. For accurate assessment of effective sizes, initial, instantaneous or asymptotic, the expressions must be applied at the lowest levels at which migration among breeding groups is nonrandom. Thus, the expressions may be applicable to lineages within socially structured populations, fragmented populations (if random exchange of genes prevails within each population), or combinations of intra- and interpopulation discontinuities of gene flow. Failure to recognize internal structures of populations may lead to considerable overestimates of inbreeding effective size, while usually underestimating variance effective size.  相似文献   

6.
7.
We consider a dioecious population having numbers of males and females that vary over time in cycles of length k. It is shown that if k is small in comparison with the numbers of males and females in any generation of the cycle, the effective population number (or size), N(e), is approximately equal to the harmonic mean of the effective population sizes during any given cycle. This result holds whether the locus under consideration is autosomal or sex-linked and whether inbreeding effective population numbers or variance effective population numbers are involved in the calculation of N(e). If, however, only two successive generations in the cycle are considered and the population changes in size between these generations, the inbreeding effective population number, N(eI), differs from the variance effective population number, N(eV). The mutation effective population number turns out to be the same as the number derived using calculations involving probabilities of identity by descent. It is also shown that, at least in one special case, the eigenvalue effective population number is the same as N(eV).  相似文献   

8.
Nielsen R  Tarpy DR  Reeve HK 《Molecular ecology》2003,12(11):3157-3164
Estimating paternity and genetic relatedness is central to many empirical and theoretical studies of social insects. The two important measures of a queen's mating number are her actual number of mates and her effective number of mates. Estimating the effective number of mates is mathematically identical to the problem of estimating the effective number of alleles in population genetics, a common measure of genetic variability introduced by Kimura & Crow (1964). We derive a new bias-corrected estimator of effective number of types (mates or alleles) and compare this new method to previous methods for estimating true and effective numbers of types using Monte Carlo simulations. Our simulation results suggest that the examined estimators of the true number of types have very similar statistical properties, whereas the estimators of effective number of types have quite different statistical properties. Moreover, our new proposed estimator of effective number of types is approximately unbiased, and has considerably lower variance than the original estimator. Our new method will help researchers more accurately estimate intracolony genetic relatedness of social insects, which is an important measure in understanding their ecology and social behaviour. It should also be of use in population genetic studies in which the effective number of alleles is of interest.  相似文献   

9.
甘蓝型油菜若干农艺性状与单株产量的关系分析   总被引:12,自引:0,他引:12  
以38个甘蓝型油菜品种为材料,对单株产量、有效分枝部位高度、主轴花序长度等11个农艺性状进行了方差分析、通径分析和聚类分析.结果显示:所有调查性状在品种间存在显著的差异;主花序长度、主序有效角果数与单株产量都有显著的遗传相关性,两者都通过有效分枝部位高度对单株产量产生较大的正向间接作用;有效分枝部位高度对单株产量的影响也较显著,高产品种具有相对较高的有效分枝部位高度;总角果数对单株产量的直接遗传通径系数虽小,但它具有最大的直接表型通径系数,它通过主序有效角果数和有效分枝数对单株产量产生了两个较大的间接作用;要获得3130kg/hm~2的产量,重点应具备果多、枝多的特征,总角果数不少于657个,有效分枝数不少于18个.  相似文献   

10.
Monitoring the rate of change in inbreeding and genetic diversity within a population is important to guide breeding programmes. Such interest stems from the impact of loss in genetic diversity on sustainable genetic gain but also the impact on performance (i.e. inbreeding depression). The objective of the present study was to evaluate trends in inbreeding and genetic diversity in 43 066 Belclare, 120 753 Charollais, 22 652 Galway, 78 925 Suffolk, 187 395 Texel, and 19 821 Vendeen purebred sheep. The effective population size for each of the six breeds was between 116.0 (Belclare population) and 314.8 (Charollais population). The Charollais population was the most genetically diverse with the greatest number of effective founders, effective ancestors, and effective founder genomes; conversely, the Belclare was the least genetically diverse population with the fewest number of effective founders, effective ancestors, and effective founder genomes for each of the six breeds investigated. Overall, the effective population sizes and the total genetic diversity within each of the six breeds were above the minimum thresholds generally considered to be required for the long-term viability of a population.  相似文献   

11.
A generalized conceptual basis for Wright's notion of effective size is presented. The concept is applied to the calculation of effective numbers based on the rate of change of genetic variability. With particular reference to the inbreeding, the eigen value, and the newly introduced "diversity" effective size, the use of the concept as a means for discrimination between and identification of various effective sizes is demonstrated.  相似文献   

12.
目的观察和评价参苓白术散加减联合酪酸梭菌活菌散治疗小儿腹泻的临床疗效。方法选取玉田县医院60例患有腹泻的儿童,随机分成观察组和对照组。对照组给予补液纠正水、电解质紊乱等常规治疗,观察组在常规治疗基础上服用参苓白术散加减联合酪酸梭菌活菌散,其中酪酸梭菌活菌散剂量为0.5g/次,3次/d,急性腹泻疗程为3~7d,慢性腹泻疗程为14~21d,观察疗效。结果观察组显效率为63.3%,有效率为33.3%,总有效率为96.6%;对照组显效率为46.7%,有效率为30.O%,总有效率为76.7%,两组比较差异有统计学意义(P〈0.05),观察组疗效明显优于对照组。结论参苓白术散加减联合酪酸梭菌活菌散治疗小儿腹泻疗效显著,能迅速恢复肠道菌群平衡和肠道生理功能,值得临床推广。  相似文献   

13.
培菲康为双歧杆菌、嗜酸乳杆菌、粪链球菌组成的人体肠道微生态活菌制剂,本文采用此制剂治疗小儿菌痢22例,有效率81.82%;小儿肠炎47例,有效率86.6%;便秘31例,有效率达87.1%。全部100例,总有效率为86%。所有病例未用抗菌药物。本文对微生态药物培菲康的药理作用及特点进行了讨论。  相似文献   

14.
小五台山亚高山草甸物种分布与温度关系研究   总被引:4,自引:2,他引:2  
通过转化糖方法、植物群落野外调查和实验室分析,分别测得生境效应温度、物种盖度和生物量,应用该数据分析小五台山亚高山草甸植物物种分布与温度的关系.结果表明,在记录到的97种维管植物中,约36%的物种分布受生境温度条件影响,约20%物种的相对盖度与温度变化呈显著相关.生物量或相对盖度与温度呈正相关的有11种植物,相对盖度与温度呈负相关的有8种植物.在物种分布与温度关系的研究中,对频度为90%~20%的物种,采用盖度指标进行分析通常可行,对频度大于90%的物种,采用生物量数据比盖度更为有效.  相似文献   

15.
Adult male and female Beagle dogs (eight total) were exposed individually, in series, to each of 23 effective temperatures for a period of 2 hours or until rectal temperature increased 1.1 degrees C. Rectal temperature was measured to the nearest 0.1 degree C by thermistor probes in the pre-test condition (basal temperature) and at each 5-minute interval during the test conditions (effective temperatures between 21.1 degrees C and 34.7 degrees C). The frequency at which dogs displayed a 1.1 degree C rise in rectal temperature was related to the magnitude of the effective temperature. At an effective temperature of 32.6 degrees C or greater, 100% of the dogs displayed a 1.1 degree C rise in rectal temperature. Between an effective temperature of 29.3 degrees C and 31.4 degrees C, some animals displayed a 1.1 degree C rise while others did not. At an effective temperature of 28.4 degrees C or below no animals displayed a 1.1 degree C rise. The mean time necessary for a 1.1 degree C rise was negatively correlated (P less than 0.01) to the magnitude of the effective temperature. The minimum effective temperature necessary to increase rectal temperature by 1.1 degree C in male Beagles (29.6 +/- 1.0 degree C) was not significantly different from females (30.8 +/- 0.4 degrees C).  相似文献   

16.
谷丙甘氨酸胶囊治疗前列腺增生32例临床疗效观察   总被引:1,自引:0,他引:1  
目的 :观察治疗前列腺疾病药物谷丙甘氨酸胶囊 (安尿通胶囊 )的临床疗效。方法 :32例前列腺增生患者 ,口服谷丙甘氨酸胶囊 ,每次 82 0mg ,tid ,一个疗程后观察排尿症状进行疗效判定。结果 :32例患者经谷丙甘氨酸胶囊治疗一个疗程后 ,显效 9例 ,有效 14例 ,无效 9例 ,总有效率 72 %。 32例患者用药期间均未发生不良反应。结论 :谷丙甘氨酸胶囊是安全有效的治疗前列腺增生的药物。  相似文献   

17.
Genetic influx into a population often does not correspond to the real migration rate (m) of individuals, due to class structure within the population. The effective migration rate (m(e)) is a concept to measure gene flow in such a situation. The ratio of the effective migration rate to the real migration rate (m(e)/m) is called the gene flow factor, and represents the degree of gene flow modification. Prior authors proposed different definitions of the effective migration rate. These may be categorized into two groups: the neutral effective migration rate and the selective effective migration rate. In this article, we construct a general model of a class-structured population with a mainland-island structure. Using the model, we prove that the gene flow factor of the neutral effective migration rate converges to the mean reproductive value of immigrants if the limit is taken with the real migration rate converging to zero. This limit theorem provides a novel interpretation of gene flow and can be used to derive approximation formulae of the neutral effective migration rate. We illustrate this method analyzing two examples, sex ratio distortion due to extrinsic factors and hybrid zones with underdominance.  相似文献   

18.
A comparison of nicotinic acid, a non-narcotic analgesic and a series of injectable and oral ergot preparations tested by various methods in treating 40 patients with typical migraine indicate that ergot alkaloids are far superior in producing symptomatic relief.A comparison of ergotamine tartrate, dihydroergotamine (DHE-45) and dihydroergocornine (DHO-180) indicated that ergotamine tartrate is the most effective and perhaps the most toxic, DHE-45 is slightly less effective and considerably less toxic, and that DHO-180 is the least effective but also the least toxic. When given orally, these alkaloids were about half as effective as when given by injection. EC-110 (ergotamine nitrate with caffeine) was the most effective.DHO-180 in liquid form, given daily for one month, had a marked preventive effect on migraine attacks.  相似文献   

19.
A comparison of nicotinic acid, a non-narcotic analgesic and a series of injectable and oral ergot preparations tested by various methods in treating 40 patients with typical migraine indicate that ergot alkaloids are far superior in producing symptomatic relief.A comparison of ergotamine tartrate, dihydroergotamine (DHE-45) and dihydroergocornine (DHO-180) indicated that ergotamine tartrate is the most effective and perhaps the most toxic, DHE-45 is slightly less effective and considerably less toxic, and that DHO-180 is the least effective but also the least toxic. When given orally, these alkaloids were about half as effective as when given by injection. EC-110 (ergotamine nitrate with caffeine) was the most effective.DHO-180 in liquid form, given daily for one month, had a marked preventive effect on migraine attacks.  相似文献   

20.
Larsen U  Yan S 《Social biology》2000,47(1-2):34-50
This paper analyzes the age pattern of effective fecundability from populations with no evidence of deliberate fertility control using a new convolution model of fecundability. The analysis is based on a sample of Hutterite birth histories from the mid-20th century, and birth histories of French Canadians from the 17th and 18th centuries. The main findings are as follows: 1) the level of effective fecundability is higher among the French Canadians compared to the Hutterites; 2) effective fecundability peaks at age 20 for the Hutterites, and in the early to mid-20s for the French Canadians; 3) Hutterite effective fecundability declines almost linearly from age 20 to 45, and French Canadian effective fecundability declines slowly from its peak to the early 30s, and more rapidly at older ages; and 4) the duration of postpartum amenorrhea is longer for the French Canadians than for the Hutterites. Because of the shorter periods of postpartum amenorrhea the Hutterites have about the same average number of children as the French Canadians, even though the French Canadians have higher effective fecundability.  相似文献   

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