On the fairness of using relative indicators for comparing citation performance in different disciplines

Relative indicators are commonly used to remove biases due to different citation practices in various scientific fields. Here we extend our recent investigation on the viability of the use of relative indicators for comparing article impact in different disciplines. We consider citation distributions for papers published in 14 of the 172 disciplines categorized by the Journal Citation Reports. The distribution of the number of citations received by publications in a certain discipline divided by the average number for the discipline is a universal function. Based on it, we compute the relative number of citations needed to be among the q percent most-cited publications in a discipline. The effect of finite samples is also discussed. The average number of citations is shown to be strongly correlated with the impact factor, but fluctuations are quite large. A similar universal distribution is found (with exceptions) when citation distributions restricted to papers published in a single journal are considered.     

A unified and universal explanation for Lévy laws and 1/f noises

Lévy laws and 1/f noises are shown to emerge uniquely and universally from a general model of systems which superimpose the transmissions of many independent stochastic signals. The signals are considered to follow, statistically, a common—yet arbitrary—generic signal pattern which may be either stationary or dissipative. Each signal is considered to have its own random transmission amplitude and frequency. We characterize the amplitude-frequency randomizations which render the system output''s stationary law and power-spectrum universal—i.e., independent of the underlying generic signal pattern. The classes of universal stationary laws and power spectra are shown to coincide, respectively, with the classes of Lévy laws and 1/f noises—thus providing a unified and universal explanation for the ubiquity of these classes of “anomalous statistics” in various fields of science and engineering.     

试论中医文献的结构

结构的一般性质具有普遍性、客观性、可分性、包容性和层次性,中医文献的结构同样具备此5种性质。因此尊重结构是研究中医文献的前提,通过结构分析来掌握中医文献所蕴涵的知识,无疑是合理的,也是可行的。并以《备急千金要方》为例,分析中医文献结构的特点。提示：结构分析对中医文献研究具有重要意义。     

Bursts of activity in collective cell migration

Dense monolayers of living cells display intriguing relaxation dynamics, reminiscent of soft and glassy materials close to the jamming transition, and migrate collectively when space is available, as in wound healing or in cancer invasion. Here we show that collective cell migration occurs in bursts that are similar to those recorded in the propagation of cracks, fluid fronts in porous media, and ferromagnetic domain walls. In analogy with these systems, the distribution of activity bursts displays scaling laws that are universal in different cell types and for cells moving on different substrates. The main features of the invasion dynamics are quantitatively captured by a model of interacting active particles moving in a disordered landscape. Our results illustrate that collective motion of living cells is analogous to the corresponding dynamics in driven, but inanimate, systems.Collective cell movement depends on intracellular biological mechanisms as well as environmental cues due to the extracellular matrix (1–5), mainly composed of collagen which is organized in hierarchical structures, such as fibrils and fibers. The mechanical properties of collagen fibril networks are essential to offer little resistance and high sensitivity to small deformations, allowing easy local remodeling and strong strain stiffening needed to ensure cell and tissue integrity (6). Wound healing is a typical biological assay to study collective migration of cells under controlled conditions in vitro and is a prototypical experimental method to study active matter (7–10). Experiments performed on soluble collagen (11) or other gels (12), micropatterned (13, 14) and deformable substrates (1) show that cell migration is guided by the substrate structure and stiffness (5, 15, 16).It has been argued that collective migration properties arise from stresses transmitted between neighboring cells (1) giving rise to long-ranged stress waves in the monolayer (17, 18). Hence the dynamics of an invading cell sheet is ruled by a combination of long-range internal stresses and interactions with the substrate, suggesting an analogy with driven elastic systems moving in a disordered medium such as cracks lines (19, 20), imbibition fronts (21), or ferromagnetic domain walls (22). The scaling laws in these systems are usually associated with a depinning critical point that has been widely studied by simple models for interface dynamics. Thanks to a combination of numerical simulations (23, 24) and renormalization group theory (23, 25–27), we now have a detailed picture of the nonequilibrium phase transitions and universality classes in these systems. Here we substantiate the analogy between collective cell migration and depinning by revealing and characterizing widely distributed bursts of activity in the collective migration of different types of cells (human cancer cells and epithelial cells, mouse endothelial cells) over different substrates (plastic, soluble, and fibrillar collagen) and experimental conditions [vascular endothelial (VE)-cadherin knockdown] and compare the experiments with simulations of a computational model of active particles (10). We find that in all these cases the statistical properties of the bursts follow universal scaling laws that are quantitatively similar to those observed in driven disordered systems (28).     

半自动生化分析仪测定总蛋白试剂盒(双缩脲法)通用性研究

目的验证半自动生化分析仪测定总蛋白试剂盒结果的一致性,为制订总蛋白试剂盒的国家标准提供可行性依据。方法采用紫外分光光度法,以质控血清(或血清)测定4个厂家总蛋白试剂盒的准确性、线性范围、精密度以及不同厂家总蛋白标准品的准确度。结果 4个厂家总蛋白试剂盒的准确性均满足要求,r≥0.99,批内精密度不超过0.30%,标准品准确度的偏差不超过2.43%。结论采用半自动生化分析仪测定不同厂家的总蛋白试剂盒是通用可行的。     

World Color Survey color naming reveals universal motifs and their within-language diversity

We analyzed the color terms in the World Color Survey (WCS) (www.icsi.berkeley.edu/wcs/), a large color-naming database obtained from informants of mostly unwritten languages spoken in preindustrialized cultures that have had limited contact with modern, industrialized society. The color naming idiolects of 2,367 WCS informants fall into three to six “motifs,” where each motif is a different color-naming system based on a subset of a universal glossary of 11 color terms. These motifs are universal in that they occur worldwide, with some individual variation, in completely unrelated languages. Strikingly, these few motifs are distributed across the WCS informants in such a way that multiple motifs occur in most languages. Thus, the culture a speaker comes from does not completely determine how he or she will use color terms. An analysis of the modern patterns of motif usage in the WCS languages, based on the assumption that they reflect historical patterns of color term evolution, suggests that color lexicons have changed over time in a complex but orderly way. The worldwide distribution of the motifs and the cooccurrence of multiple motifs within languages suggest that universal processes control the naming of colors.     

Cross-cultural recognition of basic emotions through nonverbal emotional vocalizations

Emotional signals are crucial for sharing important information, with conspecifics, for example, to warn humans of danger. Humans use a range of different cues to communicate to others how they feel, including facial, vocal, and gestural signals. We examined the recognition of nonverbal emotional vocalizations, such as screams and laughs, across two dramatically different cultural groups. Western participants were compared to individuals from remote, culturally isolated Namibian villages. Vocalizations communicating the so-called “basic emotions” (anger, disgust, fear, joy, sadness, and surprise) were bidirectionally recognized. In contrast, a set of additional emotions was only recognized within, but not across, cultural boundaries. Our findings indicate that a number of primarily negative emotions have vocalizations that can be recognized across cultures, while most positive emotions are communicated with culture-specific signals.     

Fibonacci family of dynamical universality classes

Universality is a well-established central concept of equilibrium physics. However, in systems far away from equilibrium, a deeper understanding of its underlying principles is still lacking. Up to now, a few classes have been identified. Besides the diffusive universality class with dynamical exponent z = 2, another prominent example is the superdiffusive Kardar−Parisi−Zhang (KPZ) class with z = 3/2. It appears, e.g., in low-dimensional dynamical phenomena far from thermal equilibrium that exhibit some conservation law. Here we show that both classes are only part of an infinite discrete family of nonequilibrium universality classes. Remarkably, their dynamical exponents z_α are given by ratios of neighboring Fibonacci numbers, starting with either z₁ = 3/2 (if a KPZ mode exist) or z₁ = 2 (if a diffusive mode is present). If neither a diffusive nor a KPZ mode is present, all dynamical modes have the Golden Mean z=(1+5)/2 as dynamical exponent. The universal scaling functions of these Fibonacci modes are asymmetric Lévy distributions that are completely fixed by the macroscopic current density relation and compressibility matrix of the system and hence accessible to experimental measurement.The Golden Mean, φ=1/2+5/2≈1.61803..., also called Divine Proportion, has been an inspiring number for many centuries. It is widespread in nature; i.e., arrangements of petals of the flowers and seeds in the sunflower follow the golden rule (1). Being considered an ideal proportion, the Golden Mean appears in famous architectural ensembles such as the Parthenon in Greece, the Giza Great Pyramids in Egypt, or Notre Dame de Paris in France. Ideal proportions of the human body follow the Golden Rule.Mathematically, the beauty of the Golden Mean number is expressed in its continued fraction representation: All of the coefficients in the representation are equal to unity,φ=1+11+ 11+ 11+⋱.[1]Systematic truncation of the above continued fraction gives the so-called Kepler ratios, 1/1,2/1,3/2,5/3,8/5,..., which approximate the Golden Mean. Subsets of denominators (or numerators) of the Kepler ratios form the celebrated Fibonacci numbers, Fi=1,1,2,3,5,8,.., such that Kepler ratios are ratios of two neighboring Fibonacci numbers. As well as the Golden Mean, Fibonacci ratios and Fibonacci numbers are widespread in nature (1).The occurrence of the Golden Mean is not only interesting for aesthetic reasons but often indicates the existence of some fundamental underlying structure or symmetry. Here we demonstrate that the Divine Proportion as well as all of the truncations (Kepler ratios) of the continued fraction (Eq. 1) appear as universal numbers, namely, the dynamical exponents, in low-dimensional dynamical phenomena far from thermal equilibrium. The two well-known paradigmatic universality classes, Gaussian diffusion with dynamical exponent z = 2 (2, 3) and the Kardar−Parisi−Zhang (KPZ) universality class with z = 3/2 (4), enter the Kepler ratios hierarchy as the first two members of the family.The universal dynamical exponents in the present context characterize the self-similar space−time fluctuations of locally conserved quantities, characterizing, e.g., mass, momentum, or thermal transport in one-dimensional systems far from thermal equilibrium (5). The theory of nonlinear fluctuating hydrodynamics (NLFH) has recently emerged as a powerful and versatile tool to study space−time fluctuations, and specifically the dynamical structure function that describes the behavior of the slow relaxation modes, and from which the dynamical exponents can be extracted (6).The KPZ universality class has been shown to explain the dynamical exponent observed in interface growth processes as diverse as the propagation of flame fronts (7, 8), the growth of bacterial colonies (9), or the time evolution of droplet shapes such as coffee stains (10) where the Gaussian theory fails. For a nice introduction into the KPZ class and its relevance, we refer to ref. 11. Recent reviews (12, 13) provide a more detailed account of theoretical and experimental work on the KPZ class. The dynamical structure function originating from the one-dimensional KPZ equation has a nontrivial scaling function obtained exactly by Prähofer and Spohn from the totally asymmetric simple exclusion process (TASEP) and the polynuclear growth model (14, 15) and was beautifully observed in experiments on turbulent liquid crystals (16, 17). The theoretical treatment, both numerical and analytical, of generic model systems with Hamiltonian dynamics (18), anharmonic chains (19, 20), and lattice models for driven diffusive systems (21, 22) have demonstrated an extraordinary robust universality of fluctuations of the conserved slow modes in one-dimensional systems.Despite this apparent ubiquity, dynamical exponents different from z = 2 or z = 3/2 were observed frequently. Usually, it is not clear whether this corresponds to genuinely different dynamical critical behavior or is just a consequence of imperfections in the experimental setting. Moreover, recently, a new universality class with dynamical exponent z = 5/3 for the heat mode in Hamiltonian dynamics (18) was discovered, followed by the discovery of some more universality classes in anharmonic chains (19, 20) and lattice models for driven diffusive systems (21, 22). What is lacking, even in the conceptually simplest case of the effectively one-dimensional systems that we are considering, is the understanding of the plethora of dynamical nonequilibrium universality classes within a larger framework. Such a framework exists, e.g., for 2D critical phenomena in equilibrium systems where the spatial symmetry of conformal invariance together with internal symmetries give rise to discrete families of universality classes in which all critical exponents are simple rational numbers.It is the aim of this article to demonstrate that discrete families of universality classes with fractional critical exponents appear also far from thermal equilibrium. This turns out to be a hidden feature of the NLFH equations that we extract using mode coupling theory. It is remarkable that one finds dynamical exponents z_α, which are ratios of neighboring Fibonacci numbers {1,1,2,3,5,8,…} defined recursively as F_n = F_n?1 + F_n?2. The first two members of this family are diffusion (z = 2 = F₃/F₂) and KPZ (z = 3/2 = F₄/F₃). The corresponding universal scaling functions are computed and shown to be (in general asymmetric) z_α-stable Lévy distributions with parameters that can be computed from the macroscopic current density relation and compressibility matrix of the corresponding physical system and which thus can be obtained from experiments without detailed knowledge of the microscopic properties of the system. The theoretical predictions, obtained by mode coupling theory, are confirmed by Monte Carlo simulations of a three-lane asymmetric simple exclusion process, which is a model of driven diffusive transport of three conserved particle species.     

“矛盾精髓”问题的哲学史诠释

一般与个别、普遍性与特殊性的关系问题在哲学史上有一个从本体论到认识论进而到辩证法的发展过程。哲学思维的发展和进步都与对一般与个别、普遍性与特殊性关系的理解的逐步深刻化、辩证化紧密相联。完备的辩证法理论形态的建立依赖于对一般与个别、普遍性与特殊性关系的辩证理解。一般与个别、普遍与特殊的关系问题是矛盾学说的精髓 ,为“不懂得它就等于抛弃了辩证法”提供一个哲学史的诠释