Omnidirectional connectivity of urban open spaces provides context for local government redevelopment plans

Governance of large cities requires local planning and administration, and most cities contain nested levels of government. There are challenges for coordinating urban planning and development among these local governments, which lead to the need to assess regional or city-wide contexts that can be used by smaller administrative units. Urban metabolism treats a city as a system within which the movement of resources can be estimated. In this study, we employed an urban metabolism approach to estimate the permeability of open space within an entire megacity, Seoul, the capital of South Korea. We provide district-level relative permeability scores for the 25 district governments to use in assessments and incentivize cooperation to improve the city’s overall open space connectivity. We analyzed the relative level of open space of 69 classes using Seoul’s land use map, and used Omniscape, a modeling tool that charts the level of suitability and resistance of every grid cell to every other grid cell using a moving window. This is an omnidirectional continuous approach that does not require open space “cores” or least-cost “paths”. We modeled two scenarios, one where open water is a barrier and contributes little to open space, and the other where open water is considered an attractive element to open space. We used the modeled outputs to define five levels of permeability and then compared the relative permeability scores for the 25 districts. Five districts had over 30% of their area in the lowest level, and eight of the 10 largest impermeable areas spanned across districts under water suitable scenario. The comparable metrics permit intra-district assessments to improve open space access, but also expect creative approaches to overcome issues including limited availability for open spaces.

     

On the identifiability of linear compartmental systems: a revisited transfer function approach based on topological properties

This work deals with the problem of the a priori identifiability of compartmental systems from input-output experiments. A new approach is presented, in which, having associated a directed graph with the matrix to be identified, a set of “forms” is defined which are functions of the elements of matrix itself. It is shown how, by exploiting the topological properties of the graph and its subgraphs, the problem can be simplified into one of smaller dimensions. Examples are provided to illustrate this new approach.     

Critical analysis of methods for analysing human calcium kinetics

A comparison has been made between several different compartmental and non-compartmental methods for analyzing human calcium kinetics. Using data from studies in six normal subjects, plus a computer-generated set of “error-free” data, the bone accretion rate and the exchangeable calcium pool size have been calculated by each method, along with their corresponding uncertainties. The effects of selective deletions of data have also been determined for the various methods.The results are highly dependent upon the model employed and the parameter investigated. In general, the non-compartmental models provide accretion rates which are less sensitive to measurement errors, and have less stringent requirements as to the necessary duration of an experimental study. Among compartmental models, a three-compartment model based on data collected from two hours to twenty days after isotopic calcium injection gives estimates of skeletal accretion rate and exchangeable pool size very similar to those resulting from a four-compartment model that includes additional earlier data.The relative advantages of various compartmental and non-compartmental methods of analysis are discussed in relation to these results, and practical recommendations offered to the clinical investigator.     

Dealing with Uncertainty in Risk Assessment

This paper is a commentary on Hattis’ three laws of risk assessment. The first law, that “application of standard statistical techniques to a single data set will nearly always reveal only a trivial proportion of the overall uncertainty in the parameter value” is illustrated both by examining the relevance of animal models to man and by a retrospective view of exposure conditions whose importance has only recently been recognized to be important. The second law, that “any estimate of the uncertainty of a parameter value will always itself be more uncertain than the estimate of the parameter value,” is examined in terms of a model addressing multiple levels of uncertainty, e.g., the “uncertainty in the uncertainty”. A argument is made that the number of terms needed for convergence of this uncertainty hierarchy depends on how far from the central tendency of the risk distribution one goes. The further out the “tail” of the distribution, the more terms in the uncertainty hierarchy are needed for convergence. The third law, that “nearly all parameter distribu tions look lognormal, as long as you don't look too closely,” is illustrated with a number of examples. Several reasons are put forward as to why risk variables appear so frequently to be lognormal. Recognition of the lognormal character of variable distributions can provide insight into the proper form for the associated uncertainty distributions.     

A model study of the role of proteins CLV1, CLV2, CLV3, and WUS in regulation of the structure of the shoot apical meristem

In order to elucidate the role of proteins CLV1, CLV2, CLV3, and WUS in the mechanism underlying the maintenance of compartmental structure (spatial arrangement of the zones of biosynthesis of marker proteins) of the shoot apical meristem, a model of such mechanism was developed. Computational experiments led to biologically plausible solutions only when synthesis of substance W in a space between the organizing center and meristem apex was limited by the mechanism based on interaction of CLV3 with membrane receptor CLV1/CLV2 and lower boundary of the zone of W synthesis was determined by isoline of the corresponding threshold level of substance Y concentration. The model of the “reaction-diffusion” type formalizing the role proteins CLV1/CLV2, CLV3, and WUS can describe the basis of the mechanism underlying regulation of the compartmental structure of the shoot apical meristem and positioning of the organizing center in a certain site of the cell ensemble of such meristem.     

气候变化下千金榆在我国潜在分布区预测

气候变化严重影响植物的地理分布格局,植物分布对气候变化响应的区域差异性也将为引种和保存提供重要的指导.本研究基于ArcGIS与MaxEnt模型,利用176个千金榆地理信息和13个气候变量,对当前和未来的生态位进行重建.结果表明:模型模拟当代潜在分布区可信度极高,测试集与训练集AUC值分别为0.973和0.957.主要核心适宜区集中在秦岭、长白山及其各自的邻近区域,其他为零星的“岛屿”式分布.贵州、江西、云南、福建等地未发现千金榆的分布,但存在一定的适宜分布区.随着未来气候变暖,千金榆生态适宜区明显增加,主要表现为“向高海拔地区收缩”、“北扩”和“东扩”.但核心适宜区略有减少,具体表现为“南缩”、“中稳”和“北扩”.千金榆的分布对气候变暖的响应存在明显的区域性,在东部江苏、安徽等地,因其独特的地理位置与气候环境,该地区开始成为千金榆生态适宜区;在较低纬度的南方,原有的低海拔地区可能不再适宜千金榆生存;中部秦岭地区气候为南北的渐变区,有较强的缓冲能力,气候变暖对其分布区影响不大;较高纬度的长白山地区及其邻近区域愈发适宜千金榆生存.     

International opportunities on the way up: alternative career paths of descendants of migrants from Turkey in the field of professional business services

ABSTRACT

This qualitative study examines the career paths of descendants of labour migrants from Turkey in the field of professional business services. Through in-depth interviews with upwardly mobile professionals in leading positions, the article presents evidence from four countries (France, Germany, the Netherlands and Sweden). Respondents reflect on their professional career as a process constituted through personal interactions while displaying their perceptions of restrictive national conditions that affect their professional success in this field. There seem to be three discernible “ideal type” alternative career paths for newcomers. First, the corporate career path consists of building a widely recognized “international” profile. The second alternative is a “niche” path that emerges by making use of one’s individual background in order to climb up the corporate ladder. Finally, there is a path of self-employment for individuals who have experienced blocked opportunities and therefore want to become “independent” of corporate hierarchies.     

Geometric versus topological clustering: An insight into conformation mapping

Clustering molecular conformations into “families” is a common procedure in conformational analysis of molecular systems. An implicit assumption which often underlies this clustering approach is that the resulting geometric families reflect the energetic structure of the system's potential energy surface. In a broader context we address the question whether structural similarity is correlated with energy basins, i.e., whether conformations that belong to the same energy basin are also geometrically similar. “Topological mapping” and principal coordinate projections are used here to address this question and to assess the quality of the “family clustering” procedure. Applying the analysis to a small tetrapeptide it was found that the general correlation that exists between energy basins and structural similarity is not absolute. Clusters generated by the geometric “family clustering” procedure do not always reflect the underlying energy basins. In particular it was found that the “family tree” that is generated by the “family clustering” procedure is completely inconsistent with its real topological counterpart, the “disconnectivity” graph of this system. It is also demonstrated that principal coordinate analysis is a powerful visualization technique which, at least for this system, works better when distances are measured in dihedral angle space rather than in cartesian space. © 1997 Wiley-Liss, Inc.     

MANOVA multiple comparisons using the generalized step-down procedure

If the variables in MANOVA problem can be arranged according to the order of their importance, then J. ROY'S (1958) step-down procedure may be more appropriate than the conventional invariant inference techniques. However, it may often be possible only to identify subsets such that variables within subsets are equally important and subsets are of unequal importance. In experimental situations, it is common to have a set of variables of primary interest and another of “addon” variables. The step-down reasoning is extended to such cases and a set of simultaneous confidence bounds based upon the procedure which uses the largest root criterion at each stage are derived. The confidence bounds are on all linear functions of means only that do not involve nuisance parameters, and are therefore suitable for studying the configuration of means. This method yields shorter intervals for contrasts among the means of the variables of primary interest compared with the conventional intervals based upon the largest root. The method is illustrated using BARNARD'S data (1935) on skull characters.     

The distance between bacterial species in sequence space

Despite the revolution caused by information from macromolecular sequences, the basis of bacterial classification remains the genus and the species. How do these terms relate to the variety of bacteria that exist on earth? In this paper, the inter- and intraspecies differences in amino acid sequence of several bacterial electron transport proteins, cytochromesc, and blue copper proteins are compared. For the soil and water organisms studied, bacterial species can be classed as “tight” when there is little intraspecies variation, or “loose” when this variation is large. For this set of proteins and organisms, interspecies variation is much larger than that within a species. Examples of “tight” species arePseudomonas aeruginosa andRhodobacter sphaeroides, whilePseudomonas stutzeri andRhodopseudomonas palustris are loose species. The results are discussed in the context of the origin and age of bacterial species, and the distribution of genomes in “sequence space.” The situation is probably different for commensal or pathogenic bacteria, whose population structure and evolution are linked to the properties of another organism.     

Claiming space for an engaged anthropology: spatial inequality and social exclusion

I use the concept of “engaged anthropology” to frame a discussion of how “spatializing culture” uncovers systems of exclusion that are hidden or naturalized and thus rendered invisible to other methodological approaches. “Claiming Space for an Engaged Anthropology” is doubly meant: to claim more intellectual and professional space for engagement and to propose that anthropology include the dimension of space as a theoretical construct. I draw on three fieldwork examples to illustrate the value of the approach: (1) a Spanish American plaza, reclaimed from a Eurocentric past, for indigenous groups and contemporary cultural interpretation; (2) Moore Street Market, an enclosed Latino food market in Brooklyn, New York, reclaimed for a translocal set of social relations rather than a gentrified redevelopment project; (3) gated communities in Texas and New York and cooperatives in New York, reclaiming public space and confronting race and class segregation created by neoliberal enclosure and securitization.     

The Symplechosome: a Unique Cell Organelle of some Basidiomycetes*

An unusual cell organelle of some basidiomycetes, the symplechosome, is described and illustrated in detail using Saccoblastia farinacea as an example. Symplechosomes are structurally similar, but not identical to “classical” dictyosomes of green plants and animals. As is typical for dictyosomes, each symplechosome consists of a stack of platelike cisternae. The central portions of the symplechosome-cisternae are flattened, and adjacent cisternae are separated in the mid-region by an intercisternal space of constant width. In contrast to dictyosomes, the intracisternal spaces are completely obliterated in the central area, and hexagonally arranged bars extend between adjacent cisternae. Identical bars often connect the symplechosomes with mitochondria. Symplechosomes are highly complex-structured organelles which differ significantly from the simple individual Golgi cisternae or “Golgi bodies” observed in asco- and basidiomycetes.     

Abstracts: Albany 2007, The 15th Conversation

Abstract

Forty nine molecular dynamics simulations of unfolding trajectories of the segment B1 of streptococcal protein G (GB1) provide a direct demonstration of the diversity of unfolding pathway and give a statistically utmost unfolding pathway under the physical property space. Twelve physical properties of the protein were chosen to construct a 12-dimensional property space. Then the 12-dimentional property space was reduced to a 3-dimentional principle component property space. Under the property space, the multiple unfolding trajectories look like “trees”, which have some common characters. The “root of the tree” corresponds to the native state, the “bole” homologizes the partially unfolded conformations, and the “crown” is in correspondence to the unfolded state. These unfolding trajectories can be divided into three types. The first one has the characters of straight “bole” and “crown” corresponding to a fast two-state unfolding pathway of GB1. The second one has the character of “the standstill in the middle tree bole”, which may correspond to a three-state unfolding pathway. The third one has the character of “the circuitous bole” corresponding to a slow two-state unfolding pathway. The fast two-state unfolding pathway is a statistically utmost unfolding pathway or preferred pathway of GB1, which occupies 53% of 49 unfolding trajectories. In the property space all the unfolding trajectories construct a thermal unfolding pathway ensemble of GB1. The unfolding pathway ensemble resembles a funnel that is gradually emanative from the native state ensemble to the unfolded state ensemble. In the property space, the thermal unfolded state distribution looks like electronic cloud in quantum mechanics. The unfolded states of the independent unfolding simulation trajectories have substantial overlaps, indicating that the thermal unfolded states are confined by the physical property values, and the number of protein unfolded state are much less than that was believed before.     

When will evolution lead to deceptive signaling in the Sir Philip Sidney game?

Sir Philip Sidney games are a widely used model of simple signaling. Johnstone and Grafen [Johnstone, R.A., Grafen, A., 1993. Dishonesty and the handicap principle. Animal Behaviour 46, 759–764] present a version in which the Evolutionarily Stable Strategy (ESS) is for most signalers to “honestly” signal, with a small minority of signalers who “cheat”. This model is among the most frequently cited papers on the topic of “dishonest” signaling and supports the view that signals may be “dishonest” as long as they are “honest on average”. Using genetic algorithms, we demonstrate that another solution exists to the game, an evolutionarily stable set of Nash equilibria in which members of the set never signal and all donors give their resource. Payoffs to players using this set of strategies is greater those when playing the “dishonest” signaling ESS. We demonstrate that a random population is far more likely to evolve to this non-communicating strategy set than the “dishonest” signaling ESS. We also discuss the dynamics of biological game theory models and the advances of genetic algorithms as a heuristic solution method for these models.     

Eigenvalues and structure of compartmental models

The “spread” of the nonzero eigenvalues of a compartmental matrix is studied by reference to the associated directed graph. It is related to the eigenvalues of the matrices of the individual cycles for certain strongly connected directed graphs. The equilibrium solution to the entire model is also an equilibrium solution to the model consisting of the individual cycles.