Bistability through triadic closure

We propose and analyse a class of evolving network models suitable for describing a dynamic topological structure. Applications include telecommunication, on-line social behaviour and information processing in neuroscience. We model the evolving network as a discrete time Markov chain, and study a very general framework where, conditioned on the current state, edges appear or disappear independently at the next timestep. We show how to exploit symmetries in the microscopic, localized rules in order to obtain conjugate classes of random graphs that simplify analysis and calibration of a model. Further, we develop a mean field theory for describing network evolution. For a simple but realistic scenario incorporating the triadic closure effect that has been empirically observed by social scientists (friends of friends tend to become friends), the mean field theory predicts bistable dynamics, and computational results confirm this prediction. We also discuss the calibration issue for a set of real cell phone data, and find support for a stratified model, where individuals are assigned to one of two distinct groups having different within-group and across-group dynamics

Radiocarbon and stable isotope evidence of dietary change from the Mesolithic to the Middle Ages in the iron gates: New results from Lepenski Vir

A previous radiocarbon dating and stable isotope study of directly associated ungulate and human bone samples from Late Mesolithic burials at Schela Cladovei in Romania established that there is a freshwater reservoir effect of approximately 500 yr in the Iron Gates reach of the Danube River valley in southeast Europe. Using the delta(15)N values as an indicator of the percentage of freshwater protein in the human diet, the C-14 data for 24 skeletons from the site of Lepenski Vir were corrected for this reservoir effect. The results of the paired C-14 and stable isotope measurements provide evidence of substantial dietary change over the period from about 9000 BP to about 300 BR The data from the Early Mesolithic to the Chalcolithic are consistent with a 2-component dietary system, where the linear plot of isotopic values reflects mixing between the 2 end-members to differing degrees. Typically, the individuals of Mesolithic age have much heavier delta(15)N signals and slightly heavier delta(13)C, while individuals of Early Neolithic and Chalcolithic age have lighter delta(15)N and delta(13)C values. Contrary to our earlier suggestion, there is no evidence of a substantial population that had a transitional diet midway between those that were characteristic of the Mesolithic and Neolithic. However, several individuals with "Final Mesolithic" C-14 ages show delta(15)N and delta(13)C values that are similar to the Neolithic dietary pattern. Provisionally, these are interpreted either as incomers who originated in early farming communities outside the Iron Gates region or as indigenous individuals representing the earliest Neolithic of the Iron Gates. The results from Roman and Medieval age burials show a deviation from the linear function, suggesting the presence of a new major dietary component containing isotopically heavier carbon. This is interpreted as a consequence of the introduction of millet into the human food chain

Review of \u3ci\u3eWith Good Intentions: Euro-Canadian and Aboriginal Relations in Colonial Canada\u3c/i\u3e Edited by Celia Haig-Brown and David A. Nock

This collection of essays focuses on a specific group of Euro-Canadians: those who recognized injustices and allied themselves with Aboriginal people who also saw the injustices and were actively resisting them, and worked in a variety of ways to address them. Yet the authors approach their subjects with a critical eye, realizing many of these efforts were concentrated on aboriginal peoples who missionaries thought adopted appropriate and/or useful aspects of Christianity, European dress, and settlement into farming villages or business ventures. Additionally, the authors realize some of the actors in the book struggle[d] to reconcile their Christian morality with their own desires to get ahead. Under this rubric of analysis, the chapters analyze such varied people as anthropologist Horatio Hale, aboriginal activist Nahnebahwequa, and the missionaries E. F. Wilson and Emma Crosby. Each chapter provides in-depth background to its specific subject, and most chapters locate the transformation of their subjects within the debates of the time period. The volume thus provides excellent background for anyone seeking to use missionary documents for ethnographic, geographic, or other analysis by helping to decode the biases and inherent holes. the book\u27s only weakness lies in its editors\u27 reticence about the importance of their work. While claiming that they hope these essays encourage others to look at missionaries as important sources, the introduction wastes time treading familiar and not very fertile ground about the history of colonialism and racism. If their audience is truly those who have dismissed missionaries, then they needed to sing the praises of their own essays instead of apologizing for doing white studies rather than Native studies. The volume\u27s strength is twofold. First, it uncovers those rare missionaries who bucked the system and fought colonial injustice, even if in limited and biased ways. These exceptions help us understand mainstream actors and their fears and motivations. Second, and perhaps most important, it helps demystify missionaries and the resources they left behind. They are no more and no less biased than other sources, yet social scientists have shied away from them. With Good Intentions provides the means to approach missionaries in a critical and balanced manner, and that is its greatest contribution to the field

A Bayesian approach for parameter estimation in the extended clock gene circuit of Arabidopsis thaliana

The circadian clock is an important molecular mechanism that enables many organisms to anticipate and adapt to environmental change. Pokhilko et al. recently built a deterministic ODE mathematical model of the plant circadian clock in order to understand the behaviour, mechanisms and properties of the system. The model comprises 30 molecular species (genes, mRNAs and proteins) and over 100 parameters. The parameters have been fitted heuristically to available gene expression time series data and the calibrated model has been shown to reproduce the behaviour of the clock components. Ongoing work is extending the clock model to cover downstream effects, in particular metabolism, necessitating further parameter estimation and model selection. This work investigates the challenges facing a full Bayesian treatment of parameter estimation. Using an efficient adaptive MCMC proposed by Haario et al. and working in a high performance computing setting, we quantify the posterior distribution around the proposed parameter values and explore the basin of attraction. We investigate if Bayesian inference is feasible in this high dimensional setting and thoroughly assess convergence and mixing with different statistical diagnostics, to prevent apparent convergence in some domains masking poor mixing in others

Should I Stay or should I Go?: The Effects of Student Individual Differences on Stress and Estimated Gains from the University Experience

The aim of this thesis was to identify factors at the commencement of university study that may enable prediction of both estimate of gains and experience of stresses. This was done in order to provide information that may enable early identification of risk factors in respect to student attrition. To this end, the thesis examined individual differences amongst students that relate to perception of both estimated gains and stress early in the university experience. Initially, the individual differences studied were those relating to student demographics of age, gender, whether the student performed additional part-time work and the number of hours of work performed and the influence of finances. This first round of testing was performed by distributing questionnaires examining the aforementioned via student welcome packs at commencement of university study. The results of this first round of testing suggested particular importance of intrinsic values on estimated gains. In addition to some influence of finances, gender and hours of work. From open questions present in this first round of testing, focus group questions were formulated in order to further develop the questionnaire. From the findings of study two, this was then expanded to include the influence of perceived demands, control and support and locus of control on estimated gains and subjective perceived stress. This was again performed by distributing a questionnaire at inception, albeit personally to help response rate and answer any queries. This third round of testing, as implied by the focus group responses, found an additional influence of locus of control and the perception of demands, control and support on estimated gains and stress. Finally, the fourth round of testing included biological indicators of stress, namely salivary cortisol levels through the use of analysis of levels of salivary cortisol, collected using a salivette. This final study suggested a difference in the effects of perceived demands, control and support on both perceived and biological responses to stress The study in all found that there is a definite prediction of estimate of gains from the university environment by the work values studied. Although it was found that gains were primarily influenced by intrinsic values (achievement, advancement, autonomy, personal development), an influence of extrinsic values (economics, prestige, social interaction) was also evident. In addition to work values, demographics of gender, age and hours of work were also found to influence differences in estimated gains and stress. None of the values studied were found to predict perceived stress, however the distinction between perceived and objective biological measures of stress was highlighted. In particular, with regard to the perception of demands, control and support from the university environment. The results of the study also suggested that the extent to which students perceive demands, control and support from the university environment may also have an impact on the student experience of stress, particularly biological stress, which can result in potential harm to physical well-being

Early agriculture at the crossroads of China and Southeast Asia: Archaeobotanical evidence and radiocarbon dates from Baiyangcun, Yunnan

We report archaeobotanical results from systematic flotation at what is presently the earliest Neolithic site with hard evidence for crop cultivation in the Southwestern Chinese province of Yunnan, at the site of Baiyangcun. Direct AMS dates on rice and millet seeds, included together in a Bayesian model, suggests that sedentary agricultural occupation began ca. 2650 BCE, with cultivation of already domesticated rice (Oryza sativa), broomcorn millet (Panicum miliaceum), and foxtail millet (Setaria italica). Soybean (Glycine cf. max) was also present and presumably cultivated, although it still resembles its wild progenitor in terms of seed size. Additional possible cultivars include melon (Cucumis melo) and an unknown Vigna pulse, while wild gathered resources include fruits and nuts, including hawthorn (Crateagus) and aquatic foxnut (Euryale ferox). Weed flora suggests at least some rice was cultivated in wet (flooded or irrigated fields), while dryland weeds may derive from millet fields. This subsistence system persisted throughout the site's occupation, up to ca. 2050 BCE. These data provide secure evidence for the spread of Chinese Neolithic crops to Yunnan, and provide new evidence for reconstructing possible sources of cereal agriculture in mainland Southeast Asia

Radiocarbon dates from the Oxford AMS system: archaeometry datelist 35

This is the 35th list of AMS radiocarbon determinations measured at the Oxford Radiocarbon Accelerator Unit (ORAU). Amongst some of the sites included here are the latest series of determinations from the key sites of Abydos, El Mirón, Ban Chiang, Grotte de Pigeons (Taforalt), Alepotrypa and Oberkassel, as well as others dating to the Palaeolithic, Mesolithic and later periods. Comments on the significance of the results are provided by the submitters of the material

A Rapid, Empirical Method for Detection and Estimation of Outlier Frames in Particle Imaging Velocimetry Data using Proper Orthogonal Decomposition

This paper develops a method for detection and removal of outlier images from digital Particle Image Velocimetry data using Proper Orthogonal De-composition (POD). The outlier is isolated in the leading POD modes, removed and a replacement value re-estimated. The method is used to estimate and replace whole images within the sequence. This is particularly useful, if a single PIV image is suddenly heavily contaminated with background noise, or to estimate a dropped frame within a sequence. The technique is tested on a synthetic dataset that permits the effective acquisition frequency to be varied systematically, before application to flow field frames obtained from a large-eddy simulation. As expected, outlier re-estimation becomes more difficult when the integral time scale for the flow is long relative to the sampling period. However, the method provides a systematic improvement in predicting frames compared to interpolating from neighbouring(1) frames

Valuing sustainable change in the built environment : using SuROI to appraise built environment projects

Purpose – The paper aims to assess the strengths and weaknesses SuROI to determine it suitability as a means through which social value can be predicted in line with public procurement directives and the Social Value Act, whilst at the same time as fitting the developer’s business model and CSR commitments. Design/methodology/approach – Using a multi case design, findings from a comprehensive evaluation of three major housing-led mixed use regeneration developments are presented. The tree case study locations were selected on the basis of the developer’s strong commitment to place-making and social sustainability. Together with a strong strategic desire to reposition their organisation away from the traditional business as usual profit led model. Findings - Whilst the Social Return on Investment methodology is applicable to the charity sector, its use in the built environment is highly questionable. When applying the model to the mixed use housing projects the authors identified a number of technical limitations to the model, inter alia a lack of suitable proxies and especially proxies relating to the built environment for the valuation of identified outcomes, the use of monetisation as a evaluating measure which did not support some of the more abstract or softer benefits identified, problems collecting, identifying and evaluating data to inform the model given the complexity and scale of the project, the significant time and expense associated with the valuation and finally the inability to benchmark the report on completion. These findings have implications for the social housing providers and local authorities looking to use SuROI to evaluate potential built environment projects. Originality/value – The paper offers unique insights into the viability of using existing social value measurement methodologies. The paper identifies the significant limitations associated with the SuROI methodology