| 论文/程序题目 | 作者 | 下载 | 主要内容介绍 | Hits |
| Supply–demand balance and metabolic scaling |
Jayanth R. Banavar,John Damuth |  |
It is widely accepted that metabolic rates scale across species approximately as the 34 power of mass in most if not all groups of organisms. Metabolic demand per unit mass thus decreases as body mass increases. Metabolic rates reflect both the ability of the organism’s transport system to deliver metabolites to the tissues and the rate at which the tissues use them. We show that the ubiquitous 3/4 power law for interspecific metabolic scaling arises from simple, general geometric properties of transportation networks constrained to function in biological organisms. The 3/4 exponent and other observed scaling relationships follow when mass-specific metabolic demands match the changing delivery capacities of the network at different body sizes. Deviation from the 3/4 exponent suggests either inefficiency or compensating physiological mechanisms. Our conclusions are based on general arguments incorporating the minimum of biological detail and should therefore apply to the widest range of organisms. | 604 |
| Allometric scaling in animals and plants |
Olaf Dreyer,Raymond Puzio | |
In this paper we give a derivation for the allometric scaling relation between the metabolic rate and the mass of animals and plants. We show that the characteristic scaling exponent of 3/4 occurring in this relation is a result of the distribution of sources and sinks within the living organism. We further introduce a principle of least mass and discuss the kind of flows that arise from it. | 576 |
| Allometric Scaling and Central Source Systems |
Olaf Dreyer | |
Allometric scaling relations abound in nature. Examples include the power law relating the metabolic rate of animals and plants to their masses and the power law describing the dependence of the size of the drainage basin of a river on the total amount of water contained in that river. The exponent is of the form D/D+1, where D is the dimension of the system. We show that this scaling exponent is simply a consequence of the source distribution of the systems considered and requires no further assumptions. To demonstrate the wide range of validity of the result we present a simple experiment that shows the predicted behavior in one dimension. | 570 |
| The maximum entropy formalism and the idiosyncratic theory of biodiversity |
Salvador Pueyo,Fangliang He | |
Why does the neutral theory, which is based on unrealistic assumptions, predict diversity patterns so accurately? Answering questions like this requires a radical change in the way we tackle them. The large number of degrees of freedom of ecosystems pose a fundamental obstacle to mechanistic modelling. However, there are tools of statistical physics, such as the maximum entropy formalism (MaxEnt), that allow transcending particular models to simultaneously work with immense families of models with different rules and parameters, sharing only well-established features. We applied MaxEnt allowing species to be ecologically idiosyncratic, instead of constraining them to be equivalent as the neutral theory does. The answer we found is that neutral models are just a subset of the majority of plausible models that lead to the same patterns. Small variations in these patterns naturally lead to the main classical species abundance distributions, which are thus unified in a single framework. | 630 |
| Scaling laws of marine predator search behaviour |
David W. Sims,Emily J. Southall | |
Many free-ranging predators have to make foraging decisions with little, if any, knowledge of present resource distribution and availability The optimal search strategy they should use to maximize encounter rates with prey in heterogeneous natural environments remains a largely unresolved issue in ecology1–3. Le´vy walks4 are specialized random walks giving rise to fractal movement trajectories that may represent an optimal solution for searching complex landscapes5. However, the adaptive significance of this putative strategy in response to natural prey distributions remains untested6,7. Here we analyse over a million movement displacements recorded from animal-attached electronic tags to show that diverse marine predators—sharks, bony fishes, sea turtles and penguins—exhibit Le´vy-walk-like behaviour close to a theoretical optimum2. Prey density distributions also display Le´vy-like fractal patterns, suggesting response movements by predators to prey distributions. Simulations show that predators have higher encounter rates when adopting Le´vy-type foraging in natural-like prey fields compared with purely random landscapes. This is consistent with the hypothesis that observed search patterns are adapted to observed statistical patterns of the landscape. This may explain why Le´vy-like behaviour seems to be widespread among diverse organisms3, from microbes8 to humans9, as a ‘rule’that evolved in response to patchy resource distributions. | 688 |
| The scaling laws of human travel |
D. Brockmann,L. Hufnagel | |
The dynamic spatial redistribution of individuals is a key driving force of various spatiotemporal phenomena on geographical scales. It can synchronize populations of interacting species, stabilize them, and diversify gene pools1–3. Human travel, for example, is responsible for the geographical spread of human infectious disease4–9. In the light of increasing international trade, intensified human mobility and the imminent threat of an influenza A epidemic10, the knowledge of dynamical and statistical properties of human travel is of fundamental importance. Despite its crucial role, a quantitative assessment of these properties on geographical scales remains elusive, and the assumption that humans disperse diffusively still prevails in models. Here we report on a solid and quantitative assessment of human travelling statistics by analysing the circulation of bank notes in the United States. Using a comprehensive data set of over a million individual displacements, we find that dispersal is anomalous in two ways. First, the distribution of travelling distances decays as a power law, indicating that trajectories of bank notes are reminiscent of scalefree random walks known as Le´vy flights. Second, the probability of remaining in a small, spatially confined region for a time T is dominated by algebraically long tails that attenuate the superdiffusive spread.We show that human travelling behaviour can be described mathematically on many spatiotemporal scales by a two-parameter continuous-time random walk model to a surprising accuracy, and conclude that human travel on geographical scales is an ambivalent and effectively superdiffusive process. | 714 |
| The Product Space Conditions the Development of Nations |
C. A. Hidalgo | |
Economies grow by upgrading the products they produce and export. The technology, capital, institutions, and skills needed to make newer products are more easily adapted from some products than from others. Here, we study this network of relatedness between products, or “product space,”finding that more-sophisticated products are located in a densely connected core whereas lesssophisticated products occupy a less-connected periphery. Empirically, countries move through the product space by developing goods close to those they currently produce. Most countries can reach the core only by traversing empirically infrequent distances, which may help explain why poor countries have trouble developing more competitive exports and fail to converge to the income levels of rich countries | 729 |
| 中间过程临界现象——分数阶算子理论、方法、进展及其在现代力学中的应用 |
徐明瑜,谭文长 | |
从物理学特别是力学的观点出发，简要介绍了用以描述物理和力学中的中间过程核临界现象的分数阶算子（尤指分数阶微积分和分数阶微分方程）理论、方法的最新进展以及在现代力学各个领域中的应用，其中也包括了作者今年来在这一领域所作的工作。最后，对这一学科的发展进行了展望和评价 | 742 |
| 秩序从哪里来？（讲稿） |
Jake |  |
本文件是Jake于2008年11月28日在北京科技大学的讲座《秩序从哪里来》的讲稿。该讲座内容简介： 我们都体会到，随着时间的流逝，国家会发展，科技会进步，生物会进化。秩序和复杂性总会伴随时间而增加。达尔文将这种秩序的增长过程称之为进化，基因突变、遗传选择成为了一种标准的分析范式以解释从生物到经济再到计算机中的复杂性增长问题。 几乎与达尔文同一时代，人们还发现了自然中的另一种时间之箭，即热力学第二定律。人总会衰老和死亡，屋子不打扫就会落满尘土，香水总会倾向于从瓶子中跑出来充满整个房间。热力学第二定律告诉我们，衰退很分散是不可避免的。 表面上看，生物进化与热力学第二定律形成了鲜明的矛盾。近来，一群物理学家正在从自组织的角度试图调和这一对矛盾。甚至有些人指出，如果对大量的流动而不是粒子进行统计，我们很可能得到一种全新的热力学理论，该理论有可能不仅涵盖了达尔文的生物进化论，而且有望对生态系统中的物种多样性、生命起源等传统进化论很难解释的问题提供新的见解。 值得指出，这种理论观点目前还很新，很不成熟，本讲座的目的是为了抛砖引玉，希望更多的人能够关注热力学与进化论之间的深刻联系。 | 713 |
| Statistical mechanics of money, income, and wealth: a review |
Victor M. Yakovenko | |
This is a review article originally written for Encyclopedia of Complexity and System Science, to be published by Springer http://refworks.springer.com/complexity/, and titled Econophysics, Statistical Mechanics Approach to". The terms highlighted in bold in Sec. I refer to other articles in this Encyclopedia. This paper reviews statistical models for money, wealth, and income distributions developed in the econophysics literature since late 1990s. The paper is posted at http://arxiv.org/abs/0709.3662 | 966 |
| A Thermodynamic Theory of Economics |
John Bryant | |
An analogy between thermodynamic and economic theories and processes is developed further, following a previous paper published by the author in 1982. Economic equivalents are set out concerning the ideal gas equation, the gas constant, pressure, temperature, entropy, work done, specific heat and the 1st and 2nd Laws of Thermodynamics. The law of diminishing marginal utility was derived from thermodynamic first principles. Conditions are set out concerning the relationship of economic processes to entropic gain. A link between the Le Chatelier principle and economic processes is developed, culminating in a derivation of an equation similar in format to that of Cobb Douglas production function, but with an equilibrium constant and a disequilibrium function added to it. A trade cycle is constructed, utilising thermodynamic processes, and equations are derived for cycle efficiency, growth and entropy gain. A thermodynamic model of a money system is set out, and an attempt is made to relate interest rates, the rate of return, money demand and the velocity of circulation to entropy gain. Aspects concerning the measurement of economic value in thermodynamic terms are discussed. | 878 |
| Natural selection for least action |
Ville R.I. Kaila,Arto Annila | |
The second law of thermodynamics is a powerful imperative that has acquired several expressions during the past centuries. Connections between two of its most prominent forms, i.e. the evolutionary principle by natural selection and the principle of least action, are examined. Although no fundamentally new findings are provided, it is illuminating to see how the two principles rationalizing natural motions reconcile to one law. The second law, when written as a differential equation of motion, describes evolution along the steepest descents in energy and, when it is given in its integral form, the otion is pictured to take place along the shortest paths in energy. In general, evolution is a non-Euclidian energy density landscape in flattening motion. | 895 |
| A discussion on maximum entropy production and information theory |
Stijn Bruers | |
We will discuss the maximum entropy production (MaxEP) principle based on Jaynes’ information theoretical arguments, as was done by Dewar (2003,2005). With the help of a simple mathematical model of a non-equilibrium system, we will show how to derive minimum and maximum entropy production. Furthermore, the model will help us to clarify some confusing points and to see differences between some MaxEP studies in the literature. | 761 |
| Information theory and Statistical Physics |
E.T. Jaynes | |
这篇文章为统计物理的主观学派奠定了基础。文章指出，平衡态统计物理不过是观察者由于信息的丧失导致的一种最大化熵的统计推断算法。与传统统计物理不同，Jaynes主张从最大化熵出发，而不是把熵看作是需要理论解释的终点。 | 875 |
| 人类大脑皮层的结构核心 |
林枫 | |
关于大脑皮层结构的网络研究 | 880 |
| Is utility theory so different from thermodynamics? |
Eric Smith,Dunkan Foley |  |
这种通过建立热力学同效用理论的类比，从而将统计物理模型扩展到经济学之中 | 839 |
Thermodynamics of natural selection |
Eric Smith | |
这是三篇连续的论文，主要论述生命起源、达尔文自然选择的热力学起源问题。三篇文章发表在同一期Journal of Theoretical Biology杂志上，分别从熵与热力学、化学反应中的卡诺循环、可逆计算和Landuar定理的角度论述能量流、熵与生命起源的关系。生命的起源可以看作是信息流从一大堆能量和物质流的基础上涌现而出的过程，因此这系列文章就是要论述物质和信息的关系。 | 731 |
| The Turing Test |
B. JACK COPELAND | |
Turing’s test has been much misunderstood. Recently unpublished material by Turing casts fresh light on his thinking and dispels a number of philosophical myths concerning the Turing test. Properly understood, the Turing test withstands objections that are popularly believed to be fatal. | 899 |
| Scaling theory for information networks |
Melanie E. Moses,Stephanie Forrest | |
Networks distribute energy, materials and information to the components of a variety of natural and human-engineered systems, including organisms, brains, the Internet and microprocessors. Distribution networks enable the integrated and coordinated functioning of these systems, and they also constrain their design. The similar hierarchical branching networks observed in organisms and microprocessors are striking, given that the structure of organisms has evolved via natural selection, while microprocessors are designed by engineers. Metabolic scaling theory (MST) shows that the rate at which networks deliver energy to an organism is proportional to its mass raised to the 3/4 power. We show that computational systems are also characterized by nonlinear network scaling and use MST principles to characterize how information networks scale, focusing on how MST predicts properties of clock distribution networks in microprocessors. The MST equations are modified to account for variation in the size and density of transistors and terminal wires in microprocessors. Based on the scaling of the clock distribution network, we predict a set of trade-offs and performance properties that scale with chip size and the number of transistors. However, there are systematic deviations between power requirements on microprocessors and predictions derived directly from MST. These deviations are addressed by augmenting the model to account for decentralized flow in some microprocessor networks (e.g. in logic networks). More generally, we hypothesize a set of constraints between the size, power and performance of networked information systems including transistors on chips, hosts on the Internet and neurons in the brain. | 1012 |
| 电子书：点—线—网：自然、人文、经济的网络观与实践 |
林枫 | |
本书采用通俗的写作手法，深入浅出地介绍了复杂网络、分形、复杂系统、动力系统等概念，并就它们在生命科学、经济科学等领域中的应用进行了广泛的探讨。作者是一名从事康复医学工作的研究生，却能够通晓古今、旁征博引，最终独立完成这本书的写作。 | 6582 |
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