2016-03-12 13:55:57
  foundation papers in studying complexity
  foundation papers in studying complexity
  foundation papers in Complexity
  Over the past several decades, quantum information science has emerged to seek answers to the question: can we gain some advantage by storing, transmitting and processing information encoded in systems that exhibit unique quantum properties? Today it is understood that the answer is yes, and many research groups around the world are working towards the highly ambitious technological goal of building a quantum computer, which would dramatically improve computational power for particular tasks. A number of physical systems, spanning much of modern physics, are being developed for quantum computation. However, it remains unclear which technology, if any, will ultimately prove successful. Here we describe the latest developments for each of the leading approaches and explain the major challenges for the future.
  解释合作行为演化中的“公共地悲剧”一直是生物学和社会科学中重要而又未能有效解决的核心问题之一. 现有的合作演化模型中, 描述合作行为演化的模型都是基于对称的思想发展而来, 而现实的合作系统极可能是一个非对称的系统. 但遗憾的是, 合作行为的非对称性在现有的合作演化理论中被严重地忽视了. 在一个稳定的合作系统中, 合作方的个体 数目和各自的收益与合作接受方事实上是高度不对等的. 而在个体扩散难以实现的系统中,密度依赖的干扰性竞争对合作方和合作接受方的效应将会因此存在明显区别. 本研究模型及模拟表明, 合作方之间的密度依赖的约束或干扰性竞争将能维持公共资源利用的非饱和状态, 合作系统将会因此维持合作关系局部的稳定, 在公共资源很丰富的状态下, 合作双方就不会发生竞争或冲突行为. 增强合作方个体之间的密度依赖的干扰性竞争、合作方对合作接受方的贡献率、以及丰富的公共资源三因素将提高双方的合作频率. 合作方和接受方之间的合作关系将会随系统的环境或生态条件的改变而转化为冲突关系, 双方的关系并将随这些影响因素的变化而扰动(混沌). 在非对称系统中, 合作接受方对消极合作者或欺骗者的惩罚而对合作个体的奖赏将提高合作方对合作接受方的贡献率, 即提高了类似于亲缘系数或互惠系数初始关系系数. 该初始相关系数将为合作行为的演化提供一个支点, 但该系数不能决定合作行为演化的方向. 因此, 本实验模型也有效地解释了为什么几乎所有的合作系统都存在直接的冲突.
  Theories of island biogeography and of relative species abundance are of central importance in biogeography and community ecology, yet these two bodies of theory heretofore have been largely unconnected. Incorporating speciation into the theory of island biogeography unexpectedly results in unification of these two theories. The unifed theory predicts the existence of a fundamental biodiversity number h that controls not only species richness, but also relative species abundance in the source area metacommunity at equilibrium between speciation and extinction. With additional parameters for island size and migration rate, the theory also predicts relative species abundance on islands or local regions of continuous landscapes. Application of the theory to the biogeography and biodiversity of communities of tropical trees and reefbuilding corals are discussed. One important result is that only relatively modest migration rates are su¦cient to dynamically couple the regional metacommunity and stabilize community structure on large spatiotemporal scales. Thus, regional, long-term compositional stasis in tropical rain forests and coral reefs can arise just as easily from the stabilizing e¤ect of large numbers as from nicheassembly rules that limit species membership in communities. Because of the higher intrinsic vagility of corals, the theory predicts greater regional similarity in coral reef communities than in tropical tree communities.
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