On the rational topological complexity of coformal elliptic spaces

We establish some upper and lower bounds of the rational topological complexity for certain classes of elliptic spaces. Our techniques permit us in particular to show that the rational topological complexity coincides with the dimension of the rational homotopy for some special families of coformal elliptic spaces.     

Local Fractal Connections to Characterize the Spatial Processes of Deforestation in the Ecuadorian Amazon

Deforestation by human activities is a common issue in Amazonian countries. This occurs at different spatial and temporal scales causing primary forest loss and land fragmentation issues. During the deforestation process as the forest loses connectivity, the deforested patches create new intricate connections, which in turn create complex networks. In this study, we analyzed the local connected fractal dimension (LCFD) of the deforestation process in the Sumaco Biosphere Reserve (SBR) with two segmentation methods, —CA-wavelet and K-means—to categorize the complexity of deforested patches’ connections and then relate these with the spatial processes. The results showed an agreement with both methods, in which LCFD values below 1 corresponded to isolated patches with simple shapes and those above 1 signified more complex and connected patches. From CA-wavelet a threshold of 1.57 was detected allowing us to identify and discern low and high land transformation, while the threshold for K-means was 1.61. Both values represent the region from which deforestation performs local aggressive expansion networks. The thresholds were used to map the LCFD in which all spatial processes were visually detected. However, the threshold of 1.6 ± 0.03 was more effective in discerning high land transformation. such as shrinkage and attrition, in the deforestation process in the SBR.     

Orthogonal Complement Based Divide-and-Conquer Algorithm for constrained multibody systems

A new algorithm, Orthogonal Complement based Divide-and-Conquer Algorithm (O-DCA), is presented in this paper for calculating the forward dynamics of constrained multi-rigid bodies including topologies involving single or coupled closed kinematic loops. The algorithm is exact and noniterative. The constraints are imposed at the acceleration level by utilizing a kinematic relation between the joint motion subspace (or partial velocities) and its orthogonal complement. Sample test cases indicate excellent constraint satisfaction and robust handling of singular configurations. Since the present algorithm does not use either a reduction or augmentation approach in the traditional sense for imposing the constraints, it does not suffer from the associated problems for systems passing through singular configurations. The computational complexity of the algorithm is expected to be O(n+m) and O(log(n+m)) for serial and parallel implementation, respectively, where n is the number of generalized coordinates and m is the number of independent algebraic constraints.     

Synthesis of novel bridged dinitrogen heterocycles and their evaluation as potential fragments for the design of biologically active compounds

A library of saturated bridged heterocycles based on 3,6-diazabicyclo[3.2.1]octane-2,4-dione and bispidine scaffolds (mean compound molecular weight is approximately 300 Da) with up to three stereocenters and four diversity points has been synthesized. Synthetic scaffold modifications leading to an increase in molecular complexity were studied. Well-defined stereochemical structures of both compound sets was confirmed by X-ray studies and halogenoaryl substituents were inserted appropriately for the design of novel non-basic serine protease inhibitors. Comprehensive molecular modeling has been performed for all synthesized compounds giving rationales of ligand–enzyme interactions with thrombin and trypsin. Biological testing confirmed moderate inhibitory activity of halogen-substituted saturated diazabicyclic small molecules towards thrombin.     

Suboptimality and complexity in evolution

A scalable model of biological evolution is presented which includes energy cost for building new elements and multiple paths for obtaining new functions. The model allows a population with a continual increase of complexity, but as time passes, detrimental mutations accumulate. This model shows the crucial importance of accounting for the energy cost of new structures in models of biological evolution. © 2014 Wiley Periodicals, Inc. Complexity 21: 322–327, 2015     

Degeneracy: Demystifying and destigmatizing a core concept in systems biology

Often relegated to the methods section of genetic research articles, the term “degeneracy” is regularly misunderstood and its theoretical significance widely understated. Degeneracy describes the ability of different structures to be conditionally interchangeable in their contribution to system functions. Frequently mislabeled redundancy, degeneracy refers to structural variation whereas redundancy refers to structural duplication. Sources of degeneracy include, but are not limited to, (1) duplicate structures that differentiate yet remain isofunctional, (2) unrelated isofunctional structures that are dispersed endogenously or exogenously, (3) variable arrangements of interacting structures that achieve the same output through multiple pathways, and (4) parcellation of a structure into subunits that can still variably perform the same initial function. The ability to perform the same function by drawing upon an array of dissimilar structures contributes advantageously to the integrity of a system. Drawing attention to the heterogeneous construction of living systems by highlighting the concept of degeneracy valuably enhances the ways scientists think about self‐organization, robustness, and complexity. Labels in science, however, can sometimes be misleading. In scientific nomenclature, the word “degeneracy” has calamitous proximity to the word “degeneration” used by pathologists and the shunned theory of degeneration once promoted by eugenicists. This article disentangles the concept of degeneracy from its close etymological siblings and offers a brief overview of the historical and contemporary understandings of degeneracy in science. Distinguishing the importance of degeneracy will hopefully allow systems theorists to more strategically operationally conceptualize the distributed intersecting networks that comprise complex living systems. © 2014 Wiley Periodicals, Inc. Complexity 20: 12–21, 2015     

质量文化传播与工程管理行为耦合演化的系统动力学模型研究

为了研究质量文化建设与工程管理行为以及工程绩效的耦合演化规律,对大型工程中的质量文化建设的动态特性进行了分析,运用系统动力学构建了包括质量文化传播、工作流程、人员调配以及进度压力这四个主要模块相互整合的大型工程耦合演化系统模型。系统仿真的结果表明一些管理行为因忽视了其引发的涟漪效应,导致了质量文化建设和工程建设的失败,而该模型考虑了大型工程存在的返工回路等多种动态反馈,能够帮助工程管理者理解质量文化建设存在的动态复杂性。     

The complexity of detecting fixed-density clusters

We study the complexity of finding a subgraph of a certain size and a certain density, where density is measured by the average degree. Let γ:N→Q₊ be any density function, i.e., γ is computable in polynomial time and satisfies γ(k)?k-1 for all k∈N. Then γ-CLUSTER is the problem of deciding, given an undirected graph G and a natural number k, whether there is a subgraph of G on k vertices that has average degree at least γ(k). For γ(k)=k-1, this problem is the same as the well-known CLIQUE problem, and thus NP-complete. In contrast to this, the problem is known to be solvable in polynomial time for γ(k)=2. We ask for the possible functions γ such that γ-CLUSTER remains NP-complete or becomes solvable in polynomial time. We show a rather sharp boundary: γ CLUSTER is NP-complete if γ=2+Ω(1/k^1-ε) for some ε>0 and has a polynomial-time algorithm for γ=2+O(1/k). The algorithm also shows that for γ=2+O(1/k^1-o(1)), γ-CLUSTER is solvable in subexponential time 2^no(1).