多假设成立的多agent合作决策

对复杂环境对象进行决策时,多agent合作可以融合各agent的知识经验,提高决策结果的可靠性,针对环境对象的辩识空间中多假设同时成立的决策问题,本文提出了一种基于证据理论的多agent合作决策算法,详细描述与分析了多agent合作决策的原理。为提高系统决策的可靠性,降低了合成计算的复杂度,在多agent合作决策系统中引入正确的训练案例进行学习。本文提出的算法应用于蔬菜的病害判别,实验结果验证了本文提出的多agent合作决策算法的有效性。     

系统生物学研究及其在医学中的应用

目前,系统生物学研究已初显端倪。生物学正从分子生物学走向系统生物学,由精细的分解研究转向系统的整体研究,由还原论的研究方法过渡到系统论的研究方法。简要论述了系统生物学的产生背景、结构和内容、研究思路和方法、与医学的关系等,重点介绍系统生物学的内容和研究方法,以及在疾病治疗和药物开发中的研究进展。     

The Concept of Electroosmotically Driven Flow and Its Application to Biomimetics

1　IntroductionOneaimofthephysicsscienceresearchistodevel opfundamentalandportableconceptswhichhelpunitedifferentresearchfrontiers.Inthisrespect ,Helmholtz’selectricdoublelayer (DEL)theory ,whichwasdevel opedin 1879andrelatedtheelectricandflowparame tersforelectrokinetictransport ,isaseminal,havingprovidedaframeworkforinterpretingawiderangeofelectrokineticphenomena .DespitethesimplicityoftheEDLtheory ,whichwewilldescribeindetail,ithasprovidedachallengeformathematicianstounderstanditsimplic…     

Simulating the Conversion of Rural Settlements to Town Land Based on Multi-Agent Systems and Cellular Automata

Rapid urbanization in China has triggered the conversion of land from rural to urban use, particularly the conversion of rural settlements to town land. This conversion is the result of the joint effects of the geographic environment and agents involving the government, investors, and farmers. To understand the dynamic interaction dominated by agents and to predict the future landscape of town expansion, a small town land-planning model is proposed based on the integration of multi-agent systems (MAS) and cellular automata (CA). The MAS-CA model links the decision-making behaviors of agents with the neighbor effect of CA. The interaction rules are projected by analyzing the preference conflicts among agents. To better illustrate the effects of the geographic environment, neighborhood, and agent behavior, a comparative analysis between the CA and MAS-CA models in three different towns is presented, revealing interesting patterns in terms of quantity, spatial characteristics, and the coordinating process. The simulation of rural settlements conversion to town land through modeling agent decision and human-environment interaction is very useful for understanding the mechanisms of rural-urban land-use change in developing countries. This process can assist town planners in formulating appropriate development plans.     

Cooperative Behavior of Ganglioside Molecules in Model Systems

A concise discussion of the role of different geometrical conformational states in the process of self-assembling of gangliosides is given. The report focuses on the effects of the geometrical variations occurring in the head group region of gangliosides as reflected on the geometrical properties of the whole assembly. Collective phenomena happening at the water interfacial region are found to be coupled to the phase transition of the lipid moiety, that is, to the well-known order-disorder conformational transition involving the hydrophobic tails. The possible biological relevance of the head group bistability is envisaged.     

Modes of Continuity and Change in Action Sign Systems

ABSTRACT

This paper opens with stories of continuity and change from ethnographic accounts. It proceeds to a brief examination of the use of film as a recording device for action sign systems, then to the work of two archaeologists in the field of dance and human movement. Next, the recording of sign languages is examined, and finally a case of recent transformation of a ritual (the Dominican rite of the Catholic Mass) is explored, followed by an exposure of some of the reasons why “transformations” occur in rituals, dances, and sign languages throughout the world.

Despite the growing interest among the human sciences in bodies, the notion of moving persons and their signifying acts/actions tends to remain absent from ethnographic accounts and sociocultural theory. Once it is realized that (1) people enact their selves to each other in words, movement, and other modes of action, and that (2) all human selves are culturally defined, as time/space itself is culturally defined, it then becomes possible to develop strategies for a systematic investigation of human actions.

It is argued that the adoption of movement literacy not only as a methodological resource, but as a further development in the evolution of social scientific disciplines, seems necessary. When literacy enters the picture, the understanding of continuity and change in patterned human movement across time will finally come into its own.     

Optimal Fluoridation: The Concept and Its Application to Municipal Water Fluoridation

Optimal fluoridation has been defined as that fluoride exposure which confers maximal cariostasis with minimal toxicity and its values have been previously determined to be 0.5 to 1 mg per day for infants and 1 to 1.5 mg per day for an average child.Total fluoride ingestion and urine excretion were studied in Marin County, California, children in 1973 before municipal water fluoridation. Results showed fluoride exposure to be higher than anticipated and fulfilled previously accepted criteria for optimal fluoridation. Present and future water fluoridation plans need to be reevaluated in light of total environmental fluoride exposure.     

Action of leptin on bone and its relationship to menopause

Backround: Leptin a cytokine protein secreted by adipose tissue raises considerable interest as a potential mediator of the protective effects of fat mass on bone tissue. After menopause heavier women conserve bone mass better than those with lower body weight. The protective effect of obesity on bone mass has been ascribed to a high body fat content. As Leptin levels reflect the body fat content it has emerged as a possible mediator of these protective effects. Methods: A search of the available literature focused on the role of leptin on bone tissue. Results: Both peripheral and central action of leptin on bone metabolism have been proposed. In vitro and in vivo evidence supports the hypothesis that leptin can act directly or indirectly on bone remodelling by modulating both osteoblast and osteoclast activities. However, studies in humans have not yet been able to confirm these actions possibly because of the shifting balance between stimulatory direct action and suppressive indirect action of leptin on bones via the hypothalamus. The effects of oestrogen decline and deficiency during natural or artificially induced menopause and administration of hormone replacement therapy has on leptin production remains controversial. Various studies have shown differences in leptin values in pre- and postmenopausal women. The existing clinical data on this issue are discordant. Conclusion: Larger clinical studies are necessary to clarify leptin's role in vivo and to assess the contribution of the central and peripheral role of leptin in the overall maintenance of bone turnover in human beings.     

The Action of Purifying Selection,Mutation and Drift on Fitness Epistatic Systems

For different fitness mutational models, with epistasis introduced, we simulated the consequences of drift (D scenario) or mutation, selection, and drift (MSD scenario) in populations at the MSD balance subsequently subjected to bottlenecks of size N = 2, 10, 50 during 100 generations. No “conversion” of nonadditive into additive variance was observed, all components of the fitness genetic variance initially increasing with the inbreeding coefficient F and subsequently decreasing to zero (D) or to an equilibrium value (MSD). In the D scenario, epistasis had no appreciable effect on inbreeding depression and that on the temporal change of variance components was relevant only for high rates of strong epistatic mutation. In parallel, between-line differentiation in mean fitness accelerated with F and that in additive variance reached a maximum at F ∼ 0.6–0.7, both processes being intensified by strong epistasis. In the MSD scenario, however, the increase in additive variance was smaller, as it was used by selection to purge inbreeding depression (N ≥ 10), and selection prevented between-line differentiation. Epistasis, either synergistic or antagonistic (this leading to multiple adaptive peaks), had no appreciable effect on MSD results nor, therefore, on the evolutionary rate of fitness change.THE roles of genetic drift and natural selection in shaping the genetic variation of fitness due to segregation at epistatic loci have often been discussed since Wright''s (1931) pioneering treatment of the subject. In general, the pertinent analyses have been usually elaborated within an analytical framework where changes in the mean and the components of the genetic variance exclusively due to drift were first considered, this being followed by an examination of the conditions that may subsequently allow for a more rapid selection response and/or facilitate the movement of populations to new adaptive peaks.Theoretically, it is well known that the contribution of neutral additive loci to the additive genetic variance of metric traits in populations decreases linearly as the inbreeding coefficient F increases, until it ultimately vanishes when fixation is attained (Wright 1951). For neutral nonadditive loci, however, that contribution may initially increase until a critical F value is reached and then subsequently decline to zero. This is the case of simple dominant loci (Robertson 1952; Willis and Orr 1993), and it also applies to two-locus models showing either additive × additive epistasis (Cockerham and Tachida 1988; Goodnight 1988) or more complex epistasis involving dominance at the single-locus level (Cheverud and Routman 1996; López-Fanjul et al. 1999, 2000; Goodnight 2000). Furthermore, those models have been extended to cover multiple additive × additive epistatic systems (Barton and Turelli 2004, López-Fanjul et al. 2006).In parallel, laboratory experiments have also studied the impact of population bottlenecks on the additive variance of metric traits (see reviews by López-Fanjul et al. 2003 and Van Buskirk and Willi 2006). For morphological traits not strongly correlated with fitness, a decrease in their additive variance together with little or no inbreeding depression was often observed, both results being compatible with the corresponding additive expectations and suggesting that the standing variation of those traits is mainly controlled by quasi-neutral additive alleles. Using typical estimates of mutational parameters, Zhang et al. (2004) showed that these experimental results can be explained by assuming a model of pleiotropic and real stabilizing selection acting on the pertinent trait. On the other hand, life-history traits closely connected to fitness usually show strong inbreeding depression and a dramatic increase in additive variance after a brief period of inbreeding or bottlenecking, indicating that much of that variance should be due to deleterious recessive alleles segregating at low frequencies. However, it should be kept in mind that experimental results cannot discern between simple dominance and dominance with additional epistasis as causes of inbreeding-induced changes in the additive variance.In their discussion of the shifting-balance theory (Wright 1931), Wade and Goodnight emphasized the evolutionary importance of the “conversion” of epistatic variance into additive variance, proposing that drift-induced excesses in the additive variance for fitness available to selection could enhance the potential for local adaptation, a phenomenon that was not discussed in the original formulation of Wright''s theory (Wade and Goodnight 1998; Goodnight and Wade 2000; but see Coyne et al. 1997, 2000). However, the additive variance is inflated only under restrictive conditions that often involve low-frequency deleterious recessive alleles (Robertson 1952; López-Fanjul et al. 2002), so that a drift-induced excess in the additive variance of fitness will be associated with inbreeding depression and, therefore, it is unlikely to produce a net increase in the adaptive potential of populations. In addition, previous considerations were based on the theoretical analysis of the behavior of neutral genetic variation after bottlenecks, and the role of selection acting on epistatic systems controlling fitness has not been studied.In this article we used analytical and simulation methods to investigate the contribution of epistatic systems to the change in the mean and the genetic components of variance of fitness during bottlenecking, due to the joint action of mutation, natural selection, and genetic drift (MSD). To develop a biologically reasonable model, we assumed that mutations show a distribution of homozygous and heterozygous effects close to those experimentally observed in Drosophila melanogaster, and we imposed different types of epistasis on this basic system. The pattern and strength of epistatic effects on fitness is largely unknown, but synergism between homozygous deleterious mutations at different loci has often been reported in Drosophila mutation-accumulation experiments (Mukai 1969; Ávila et al. 2006). Therefore, we studied the consequences of synergistic epistasis in pairs of loci by increasing the deleterious effect of the double homozygote above that expected from the deleterious effects of the homozygotes at both loci involved. However, to explore the consequences of bottlenecking in a multiple-peak adaptive surface, we also considered cases of antagonistic epistasis where, at each pair of loci, the fitness of the double homozygote for the deleterious alleles was larger than expected. Of course, other epistatic models could also be considered, including those showing higher-order interaction effects, but the severe shortage of relevant empirical data makes the choice highly subjective and, consequently, we restricted our analysis to the simplest case. On the other hand, our procedure has the practical advantage of allowing the definition of epistasis by the addition of a single parameter to those describing the properties of individual loci.Our aim was to describe and analyze drift-induced changes in the components of the genetic variance of fitness, where neutral predictions will be reliable only during extreme and brief bottlenecks. For moderate bottleneck sizes or long-term inbreeding, it becomes necessary to consider the concurrent effects of natural selection both on the standing variation and on that arisen by new mutation. Moreover, the nature of the genetic variability of fitness in the base population, arisen by mutation and shaped by natural selection and drift, is critical for the assessment of the consequences of subsequent bottlenecks. For nonepistatic models, the genetic properties of the trait can be theoretically inferred from the pertinent mutational parameters and effective population sizes by assuming a balance between mutation, selection, and drift. This can be numerically achieved using diffusion theory, and reliable approximations can be easily calculated by analytical methods (García-Dorado 2007). Notwithstanding, the analytical study of the contribution of epistasis to the genetic properties of fitness at the MSD balance becomes particularly difficult and it must be complemented with computer simulation.     

The earth and its life: Systems perspective

From the planetary point of view, the Earth can be imagined as a system comprised of interwined natural populations propagated through time via recycling. This recycling, or birth/death process, imposes age patterns on natural populations of the solid earth, hydrosphere, atmosphere and living entities. Mathematically, the concept is analogous to that of population dynamics in living systems. The populations of the Earth system form a hierarchical structure. The hierarchy of geological tectonic realms contains populations of 10²⁴–10²⁶ gr in size, with half-lives in the 10⁷–10⁹ yr time range. The approximate parameters for the oceans are 10²⁴ gr and 10²–10⁷ yr, for the atmosphere 10²¹ gr and 10^–2–10⁷ yr, and for living systems 10¹⁴–10¹⁹ gr and 10^–3–10² yr, respectively. In this perspective, and in departure from the GAIA hypothesis, the subordinate populations, such as those of living systems, are constrained to operate within limits imposed by the larger, and slower, hierarchies. They can overstep the imposed limits only on time scales shorter than the response time of the dominant populations. Isotopic record of past sea water shows that on time scales of 10⁷ yr the solid earth, hydrosphere, atmosphere and life act as a unified system controlled by tectonics, that is by the hierarchy of the solid earth.     

Application of Spin Traps to Biological Systems

Since 1971. when nitroxides were first reported to be bioreduced, several cellular enzymes, in addition to ascorbic acid. have been found to catalyze the reduction of nitroxides to their corresponding hydroxylami-nes. Numerous studies have demonstrated that cellular bioreduction of nitroxides are both dependent upon the structure of the nitroxide and cell type. For example, pyrrolidinyloxyls are considerably more resistant to bioreduction than their corresponding piperidinyloxyls. In addition, cellular levels of reductases present in freshly isolated rat hepatocytes are considerably greater than concentrations found in freshly isolated rat enterocytes. Thus, through the proper selection of a cell type and an appropriate nitroxide. one can study cellular-mediated free radical processes.

With the discovery that α-hydrogen-containing nitroxides, including 2, Z-dimethyl-S-hydroxy-l-pyrrolidinyloxyl (DMPO-OH) decompose rapidly in the presence of superoxide and thiols, the ability to determine if hydroxyl radical is generated during stimulation of human neutrophils, is in doubt. To explore the limits of spin trapping in this context. we have studied the effect of varying the rates of superoxide production. in the presence and absence of thiols, on the decomposition of DMPO-OH. In parallel studies, we have found that t-butyl α-methyl-4-pyridinyl-N-oxide nitroxide (4-POBN-CH₃) will not degrade in the presence of superoxide and a thiol. From these studies. we have determined that if hydroxyl radicals were generated as an isolated event in the presence of a continual flow of superoxide. spin trapping might not be able to detect its formation. Otherwise. spin trapping should be able to measure hydroxyl radicals. if continually generated, during activation of human neutrophils.     

The Cochlear CRF Signaling Systems and their Mechanisms of Action in Modulating Cochlear Sensitivity and Protection Against Trauma

A key requirement for encoding the auditory environment is the ability to dynamically alter cochlear sensitivity. However, merely attaining a steady state of maximal sensitivity is not a viable solution since the sensory cells and ganglion cells of the cochlea are prone to damage following exposure to loud sound. Most often, such damage is via initial metabolic insult that can lead to cellular death. Thus, establishing the highest sensitivity must be balanced with protection against cellular metabolic damage that can lead to loss of hair cells and ganglion cells, resulting in loss of frequency representation. While feedback mechanisms are known to exist in the cochlea that alter sensitivity, they respond only after stimulus encoding, allowing potentially damaging sounds to impact the inner ear at times coincident with increased sensitivity. Thus, questions remain concerning the endogenous signaling systems involved in dynamic modulation of cochlear sensitivity and protection against metabolic stress. Understanding endogenous signaling systems involved in cochlear protection may lead to new strategies and therapies for prevention of cochlear damage and consequent hearing loss. We have recently discovered a novel cochlear signaling system that is molecularly equivalent to the classic hypothalamic–pituitary–adrenal (HPA) axis. This cochlear HPA-equivalent system functions to balance auditory sensitivity and susceptibility to noise-induced hearing loss, and also protects against cellular metabolic insults resulting from exposures to ototoxic drugs. We review the anatomy, physiology, and cellular signaling of this system, and compare it to similar signaling in other organs/tissues of the body.     

离子束对生物体的作用原理及应用

离子束是指一束具有一定能量的质量数小于或等于4的带电离子束,离子束注入技术是生物物理技术,具有生理损伤小、突变谱广和突变频率高等特点。离子束与生物体的相互作用是我国具有独立知识产权的生物物理技术,我国科学家在上世纪80年代已经发现了离子束注入的生物效应,并将这一原理应用于植物诱变育种。本文主要概述了低能离子束注入对生物体的作用原理,以及该技术在植物育种、微生物品种改良和遗传改良上的应用,最后还小结了离子束注入技术在研究领域存在的问题并对其未来发展方向提出展望。     

An Electrokinetic Interpretation of the Functioning of Biological Systems and its Application to the Study of Mineral Salts Absorption

An attempt has been made to apply an electrokinetic approachto describe the functioning of biological systems. Using anohmic expression, it is possible to construct models as effectiveas those of Michaelis-Menten kinetics to interpret experimentaldata. While retaining the notions of competitive and non-competitiveinteractions it replaces the parameters K_m and V_m by log (B/[P])and A/r which have simple biological meanings. In addition,the approach is well adapted to the analysis of problems presentedby complex systems working in series or parallel, coupled systemsand networks of reactions. By the use of a non-ohmic expressionthe electrokinetic approach attributes a semi-conductor-likecomponent to catalytic systems in the cell. The approach isconsistent with the data of quantum mechanics and it predictsthe existence of a third type of interaction, perhaps equivalentto allosteric interactions. Applied to the problem of absorptionit leads to an explanation of experimental results without thenecessity of invoking the presence of two carrier systems.     

Application of Dibenzoate Chirality Rule to Flexible Systems

The chiroptical properties of (+)-(1S,2S)-dibenzoxycycloheptane and (+)-(lS,2S)-dibenzoxycyclooctane were observed. The dibenzoate chirality rule for chiral dibenzoxycyclohexanes was successfully applicable to these medium-sized ring compounds as well. The conformation of the open chain dibenzoates was discussed on the basis of the chiroptical properties found for the dibenzoate and di-p-nitrobenzoate of (+)-(2S,3S)-butane-diol.