Effects of the topology of social networks on information transmission

Social behaviours cannot be fully understood without considering the network structures that underlie them. Developments in network theory provide us with relevant modelling tools. The topology of social networks may be due to selection for information transmission. To investigate this, we generated network topologies with varying proportions of random connections and degrees of preferential attachment. We simulated two social tasks on these networks: a spreading innovation model and a simple market. Results indicated that non-zero levels of random connections and low levels of preferential attachment led to more efficient information transmission. Theoretical and practical implications are discussed

Body mass index and health care utilization in diabetic and nondiabetic individuals.

BackgroundAlthough controversial, most studies examining the relationship of body mass index (BMI) with mortality in diabetes suggest a paradox: the lowest risk category is above normal weight, versus normal weight in nondiabetic persons. One proposed explanation is greater morbidity of diabetes in normal weight persons. If this were so, it would suggest a health care utilization paradox in diabetes, paralleling the mortality paradox, yet no studies have examined this issue.ObjectiveTo compare the relationship of BMI with health care utilization in diabetic versus nondiabetic persons.DesignPopulation-based cross-sectional study.SubjectsAdults in the 2000-2011 Medical Expenditures Panel Surveys (N=120,389).MeasuresTotal health care expenditures, hospital utilization (≥1 admission), and emergency department utilization (≥1 visit). BMI (kg/m) categories were: <20 (underweight); 20 to <25 (normal); 25 to <30 (overweight); 30 to <35 (obese); and ≥35 (severely obese). Adjustors were age, sex, race/ethnicity, income, health insurance, education, smoking, co-morbidity, urbanicity, region, and year.ResultsAmong diabetic persons, adjusted mean total health care expenditures were significantly lower in obese versus normal weight persons ($1314, 95$513-$2115; P=0.001). By contrast, among nondiabetic persons, total expenditures were nonsignificantly higher in obese versus normal weight persons (-$229, 95% CI, -$460 to$2; P=0.052). Findings for hospital and emergency department utilization exhibited similar patterns.ConclusionsNormal weight diabetic persons used substantially more health care than their overweight and obese counterparts, a difference not observed in nondiabetic persons. These differences support the plausibility of a BMI mortality paradox related to greater morbidity of diabetes in normal weight than in heavier persons

Social learning mechanisms compared in a simple environment

Social learning can be adaptive, but little is known about the underlying mechanisms. Many researchers have focused on imitation but this may have led to simpler mechanisms being underestimated. We demonstrate in simulation that imitative learning is not always the best strategy for a group-living animal, and that the effectiveness of any such strategy will depend on details of the environment and the animal's lifestyle. We show that observations of behavioural convergence or "traditions" might suggest effective social learning, but are meaningless considered alone

Cluster-variation approximation for a network-forming lattice-fluid model

We consider a 3-dimensional lattice model of a network-forming fluid, which has been recently investigated by Girardi and coworkers by means of Monte Carlo simulations [J. Chem. Phys. \textbf{126}, 064503 (2007)], with the aim of describing water anomalies. We develop an approximate semi-analytical calculation, based on a cluster-variation technique, which turns out to reproduce almost quantitatively different thermodynamic properties and phase transitions determined by the Monte Carlo method. Nevertheless, our calculation points out the existence of two different phases characterized by long-range orientational order, and of critical transitions between them and to a high-temperature orientationally-disordered phase. Also, the existence of such critical lines allows us to explain certain ``kinks'' in the isotherms and isobars determined by the Monte Carlo analysis. The picture of the phase diagram becomes much more complex and richer, though unfortunately less suitable to describe real water.Comment: 10 pages, 9 figures, submitted to J. Chem. Phy

Computations on Sofic S-gap Shifts

Let $S=\{s_{n}\}$ be an increasing finite or infinite subset of $\mathbb N \bigcup \{0\}$ and $X(S)$ the $S$-gap shift associated to $S$. Let $f_{S}(x)=1-\sum\frac{1}{x^{s_{n}+1}}$ be the entropy function which will be vanished at $2^{h(X(S))}$ where $h(X(S))$ is the entropy of the system. Suppose $X(S)$ is sofic with adjacency matrix $A$ and the characteristic polynomial $\chi_{A}$. Then for some rational function $Q_{S}$, $\chi_{A}(x)=Q_{S}(x)f_{S}(x)$. This $Q_{S}$ will be explicitly determined. We will show that $\zeta(t)=\frac{1}{f_{S}(t^{-1})}$ or $\zeta(t)=\frac{1}{(1-t)f_{S}(t^{-1})}$ when $|S|<\infty$ or $|S|=\infty$ respectively. Here $\zeta$ is the zeta function of $X(S)$. We will also compute the Bowen-Franks groups of a sofic $S$-gap shift.Comment: This paper has been withdrawn due to extending results about SFT shifts to sofic shifts (Theorem 2.3). This forces to apply some minor changes in the organization of the paper. This paper has been withdrawn due to a flaw in the description of the adjacency matrix (2.3

The impact of space and space-related activities on a local economy. a case study of boulder, colorado. part ii- the income-product accounts

Total impact of space and space related activities on local economy of Boulder, Colorado - income-product account

Thermodynamic anomalies in a lattice model of water: Solvation properties

We investigate a lattice-fluid model of water, defined on a 3-dimensional body-centered cubic lattice. Model molecules possess a tetrahedral symmetry, with four equivalent bonding arms. The model is similar to the one proposed by Roberts and Debenedetti [J. Chem. Phys. 105, 658 (1996)], simplified by removing distinction between "donors" and "acceptors". We focus on solvation properties, mainly as far as an ideally inert (hydrophobic) solute is concerned. As in our previous analysis, devoted to neat water [J. Chem. Phys. 121, 11856 (2004)], we make use of a generalized first order approximation on a tetrahedral cluster. We show that the model exhibits quite a coherent picture of water thermodynamics, reproducing qualitatively several anomalous properties observed both in pure water and in solutions of hydrophobic solutes. As far as supercooled liquid water is concerned, the model is consistent with the second critical point scenario.Comment: 12 pages, 9 figures, 1 tabl

Pleading with the Emperor: Pax Americana and the Transformation of Environmental Governance

The combined effects of the globalisation and integration of productive networks of capital, the hegemony of neo-liberal discourse in the framing of policy toward capital markets, the unchallenged dominance of the US military, the establishment of the International Monetary Fund (IMF), World Bank (WB) and World Trade Organisation (WTO), and the more recent signing of bilateral free trade agreements(BITs) have circumscribed the ability of governments to exercise sovereignty in the creation of environmental policy. The resultant capacity to "insulate policy from the chaos of politics" (Economist 1994, 9) has prompted a number of authors to situate issues of global governance within the context of Empire. In this paper, we chart the re-emergence of Empire as concept and phenomena. In the first section, we identify three schools of thought that invoke the concept of Empire: the image of Pax Americana held by US neoconservatives for whom Empire is a reality justified by the necessities of geo-political power; the liberal-humanitarianism of European foreign policy elites who argue for a multi-polar Empire to balance American power; and the complex multi-dimensional entity of domination depicted by the global justice movement. We reveal the tensions that exist between Empire’s agents, most notably between a vision of a multi-polar Empire and that of Pax Americana. Through the work of Hardt and Negri, Harvey and Foucault, we develop an operational concept of Empire to explore how the tensions between the agents of Empire manifest as a global system of governance. Drawing on this analysis, we discuss the implications of Empire for environmental politics and policy through a case-study of the Australian-United States Free Trade Agreement (AUSFTA) to illustrate the complex, multiform strategies of power operating in the maintenance and transformation of Empire