Solvent-based deuterium isotope effects on the redox thermodynamics of cytochrome<Emphasis Type="Italic"> c</Emphasis>

The reduction thermodynamics of cytochrome c (cytc), determined electrochemically, are found to be sensitive to solvent H/D isotope effects. Reduction of cytochrome c is enthalpically more favored in D₂O with respect to H₂O, but is disfavored on entropic grounds. This is consistent with a reduction-induced strengthening of the H-bonding network within the hydration sphere of the protein. No significant changes in E° occur, since the above variations are compensative. As a main result, this work shows that the oxidation-state-dependent differences in protein solvation, including electrostatics and solvent reorganization effects, play an important role in determining the individual enthalpy and entropy changes of the reduction process. It is conceivable that this is a common thermodynamic feature of all electron transport metalloproteins. The isotope effects turn out to be sensitive to buffer anions which specifically bind to cytc. Evidence is gained that the solvation thermodynamics of both redox forms of cytc are sensibly affected by strongly hydrated anions.     

Multiple comparison of entropies with application to dinosaur biodiversity

Summary. Did the biodiversity of dinosaurs decline, or did it remain more or less constant before their mass extinction 65 million years ago? Sheehan et al. (1991, Science, 835–839) reported that the biodiversity of families of dinosaur species remained more or less constant preceding their extinction, suggesting extinction due to a cataclysmic event such as an asteroid strike. But that claim was based on the incorrect interpretation that a large p value associated with a test of null hypothesis of equality supports that null hypothesis. To assess whether there is a basis for such a claim, we formulate the problem as one of practical equivalence, in analogy to bioequivalence. We then develop reliable practical equivalence confidence intervals for differences of entropies by applying the bootstrap-t technique to a nearly pivotal quantity. Confidence intervals for changes in the biodiversity of dinosaurs are then computed, allowing the reader to assess whether there is evidence of near constancy of dinosaur biodiversity before extinction.     

A new method based on entropy theory for genomic sequence analysis

We have refined entropy theory to explore the meaning of the increasing sequence data on nucleic acids and proteins more conveniently. The concept of selection constraint was not introduced, only the analyzed sequences themselves were considered. The refined theory serves as a basis for deriving a method to analyze non-coding regions (NCRs) as well as coding regions. Positions with maximal entropy might play the most important role in genome functions as opposed to positions with minimal entropy. This method was tested in the well-characterized coding regions of 12 strains of Classical Swine Fever Virus (CSFV) and non-coding regions of 20 strains of CSFV. It is suitable to analyze nucleic acid sequences of a complete genome and to detect sensitive positions for mutagenesis. As such, the method serves to formulate the basis for elucidating the functional mechanism.     

Quantifying energy dissipation by grazing animals in harsh environments

Grazing systems in harsh environments are common throughout the world, and animal production is the mainstay of the livelihoods of many resource-poor farmers. The energy cost of the various activities involved in the process of harvesting the pasture to transform it into animal product can be estimated through an energy balance. This cost would be the difference between the metabolizable energy intake (MEI) and the energy expenditures for maintenance (MEm), temperature regulation (MEtr), and the energy for production (MEp). Each of the ME has its own net energy (NE) and its associated efficiency (K). When MEI>MEm+MEtr+MEp, the difference is attributable to the energy dissipated during grazing. The efficiency of converting the energy consumed into animal products depends on the magnitude of the dissipation. The inefficiency is associated with the energy spent in locomotion and the stress produced when there is low availability of energy in the pasture. This paper presents a method to quantify the dissipation of energy by grazing animals by considering it as a function of available energy. Such an understanding is required in order to develop management strategies to increase conversion efficiency.     

Darwinian fitness and the intensity of natural selection: studies in sensitivity analysis

Darwinian fitness, the capacity of a variant type to establish itself in competition with the resident population, is determined by evolutionary entropy, a measure of the uncertainty in age of the mother of a randomly chosen newborn. This article shows that the intensity of natural selection, as measured by the sensitivity of entropy with respect to changes in the age-specific fecundity and mortality variables, is a convex function of age, decreasing at early and increasing at later ages. We exploit this result to provide quantitative evolutionary explanations of the large variation in survivorship curves observed in natural populations. Previous studies to explain variation in survivorship curves have been based on the proposition that Darwinian fitness is determined by the Malthusian parameter. Hence the intensity of natural selection will be determined by the sensitivity of the Malthusian parameter with respect to changes in the age-specific fecundity and mortality variables. This measure of the selection gradient is known to be a decreasing function of age, with implications which are inconsistent with empirical observations of survivorship curves in human and animal populations. The analysis described in this paper point to the mitigated import of sensitivity studies based on the Malthusian parameter. Our analysis provides theoretical and empirical support for the ecological and evolutionary significance of sensitivity analysis based on entropy, which is the appropriate measure of Darwinian fitness.     

On “Entropy consumption in primary photosynthesis” by Jennings et al.

The preceding paper [R.C. Jennings, E. Belgio, A.P. Casazza, F.M. Garlaschi, G. Zucchelli, Entropy consumption in primary photosynthesis, Biochim. Biophys. Acta (in press)] is criticized on several grounds.     

Natural distribution

Log-normal distributions describe data from diverse disciplines of science. However, the fundamental basis of log-normal distributions is unknown. We suggest that the skewed distributions are outcomes of natural processes i.e. they result from the principle of increasing entropy. Fluctuations during the course of evolution toward more probable states yield multiplicative variations about the mean. The non-linear dispersion of thermodynamic states, i.e. matter and energy defined by chemical potentials, underlies the skew. Cumulative curves of skewed distributions without integrable analytical forms are characteristic of natural processes.     

Consensual predictions of potential distributional areas for invasive species: a case study of Argentine ants in the Iberian Peninsula

Invasive species are known to influence the structure and function of invaded ecological communities, and preventive measures appear to be the most efficient means of controlling these effects. However, management of biological invasions requires use of adequate tools to understand and predict invasion patterns in recently introduced areas. The present study: (1) estimates the potential geographic distribution and ecological requirements of the Argentine ant (Linepithema humile Mayr), one of the most conspicuous invasive species throughout the world, in the Iberian Peninsula using ecological niche modeling, and (2) provides new insights into the process of selection of consensual areas among predictions from several modeling methodologies. Ecological niche models were developed using 5 modeling techniques: generalized linear models (GLM), generalized additive models (GAM), generalized boosted models (GBM), Genetic Algorithm for Rule-Set Prediction (GARP), and Maximum Entropy (Maxent). Models for the eastern and western portions of the Iberian Peninsula were built using subsets of occurrence and environmental data to investigate the potential for ecological niche differences between the invading populations. Our results indicate geographic differences between predictions of different approaches, and the utility of ensemble predictions in identifying areas of uncertainty regarding the species’ invasive potential. More generally, our models predict coastal areas and major river corridors as highly suitable for Argentine ants, and indicate that western and eastern Iberian Peninsula populations occupy similar environmental conditions.

基于多目标的杨树速生丰产林主伐决策分析

经济效益综合评价是产业决策研究的重要内容.从系统工程观点来看,经济效益综合评价本质上是一个有限方案多目标决策问题.因此,本文采用多目标决策法对杨树速生丰产林的主伐决策进行研究,以年均净现值、内部收益率、土地期望价、效益成本比、成本利润率为指标,提出用熵技术法确定评价指标权重,结合"理想点"法、TOPSIS法和线性加权和法三种方法对决策方案进行排序择优,得到不同排序结果,最后用平均值法得到最终综合评价结果.结果表明,对所研究的密度为10×10m~2、8×8m~2、6×8m~2、5×6m~2的杨速生丰产林进行分析得到综合评价结果,其最优主伐龄分别为:13年、10年、9年、9年.随着密度的增大,经济成熟龄提前.本研究表明该方法对杨树速生丰产林的主伐决策研究是有效可行的.     

利用最大熵模型和规则集遗传算法模型预测孑遗植物裸果木的潜在地理分布及格局

利用野外调查的16个居群分布点和7个环境因子图层, 选择最大熵模型(MAXENT)和规则集遗传算法模型(GARP), 在地理和环境空间上模拟了第三纪孑遗植物裸果木(Gymnocarpos przewalskii)在中国西北地区的潜在分布。结果表明: (1)裸果木的潜在适生区全部集中在西北荒漠区, 其中最佳适生区主要集中在3个区域, 一是河西走廊中部和玉门以西、宁夏北部及内蒙古乌拉特后旗; 二是塔里木盆地西北缘; 三是柴达木盆地西北缘两片极小的高度适生区。裸果木的生态位被确定在一个较广的干旱环境空间: 适生区极端最高气温基本上在29.2-36.8 ℃之间, 极端最低气温在-18.3至-13.4 ℃之间; 年平均降水量40-200 mm; 潜在蒸发率在3-15之间。(2) MAXENT和GARP模型都较好地预测了裸果木的潜在分布, 但GARP产生了相对较大、较连续的潜在分布区, 部分过预测了破碎化生境; 而MAXENT预测到的潜在分布区, 在不同区域具有不同的环境适生性指数, 而且成功地排除了不合理的破碎化分布, 从而更直观地展示了裸果木的潜在分布格局和生态位要求。