Self-organization and time-stability of social hierarchies

The formation and stability of social hierarchies is a question of general relevance. Here, we propose a simple generalized theoretical model for establishing social hierarchy via pair-wise interactions between individuals and investigate its stability. In each interaction or fight, the probability of "winning" depends solely on the relative societal status of the participants, and the winner has a gain of status whereas there is an equal loss to the loser. The interactions are characterized by two parameters. The first parameter represents how much can be lost, and the second parameter represents the degree to which even a small difference of status can guarantee a win for the higher-status individual. Depending on the parameters, the resulting status distributions reach either a continuous unimodal form or lead to a totalitarian end state with one high-status individual and all other individuals having status approaching zero. However, we find that in the latter case long-lived intermediary distributions often exist, which can give the illusion of a stable society. As we show, our model allows us to make predictions consistent with animal interaction data and their evolution over a number of years. Moreover, by implementing a simple, but realistic rule that restricts interactions to sufficiently similar-status individuals, the stable or long-lived distributions acquire high-status structure corresponding to a distinct high-status class. Using household income as a proxy for societal status in human societies, we find agreement over their entire range from the low-to-middle-status parts to the characteristic high-status "tail". We discuss how the model provides a conceptual framework for understanding the origin of social hierarchy and the factors which lead to the preservation or deterioration of the societal structure.Comment: Added sections 4.1 and S2.A about agonistic interactions in animals, added sections 4.2.1 and S2.B regarding potential proxies for societal status in non-human animals, added references to sections 1 and 2. Main text: 34 pages, 11 figures. Supplementary appendices: 36 pages, 24 figure

Simple model of market structure evolution of service-providing firms

Service-providing firms compete for clients, creating market structures ranging from domination by a few giant companies to markets in which there are many small firms. These market structures evolve in time, and may remain stable for many years before experiencing a disruption in which a new firm emerges and rapidly obtains a large market share. We seek the simplest realistic model giving rise to such diverse market structures and dynamics. We focus on markets in which every client adopts a single firm, and can, from time to time, switch to a different firm. The markets of cell phone and Internet service providers are examples. In the model, the size of a particular firm, labelled i, is equal to its current number of clients, ni. In every step of the simulation, a client is chosen at random, and then selects a firm from among the full set of firms with probability pi = (beta + ni^alpha)/K, where K is the normalization factor. Our model thus has two parameters: alpha represents the degree to which firm size is an advantage (alpha > 1) or disadvantage (alpha < 1), relative to strict proportionality to size (alpha = 1), and beta represents the degree to which small firms are viable despite their small size. We postulate that alpha and beta are determined by the regulatory, technology, business culture and social environments. The model exhibits a phase diagram in the parameter space, with different regions of behaviour. In one region, oligopolies form in which a few large firms evenly split the market. In another, the market is divided into several firms with clearly defined ranks. (...) We compare the model to the markets of cell phone service providers in Germany and Canada, and find that it correctly predicts that the leader firm of the German market changes more often compared to leader firm changes in Canada, which is a more stable market.Comment: 31 pages, 10 figures, Appendi

The Influence of Landmark Judgments and Statutory Changes on the Family Litigation Explosion: A Citation Network Analysis

Family law in many countries has changed radically since the 1960s. However, despite family law’s central importance, few detailed quantitative analyses of the relationship between legal developments (landmark judgments and statutory changes) and the amount and subject of family litigation have been made. We examine this relationship using a unique dataset of citations among Canadian family law judgments from all levels of the court hierarchy. The network analysis draws attention to significant changes in law and legal practice over time. Not only did litigation increase overall, but the number of judgments involving multiple legal issues grew dramatically in the mid-1990s, signaling the increasing complexity of litigation surrounding family breakdowns. We probe this emergent co-occurrence of legal issues using citation network analysis and find clear links to the jurisprudential changes introduced through the landmark 1992 judgment Moge v Moge and the 1997 Federal Child Support Guidelines

The Academic Elite in SixSocial Science Disciplines: Linkages Among Top-Ranked Graduate Departments

In 1981 the National Academy of Sciences initiated an evaluation by faculty of the quality of doctoral programs in the social sciences. Changing Times listed the top tell percent of all graduate programs in the social sciences based upon a combination 01two variables from the National Academy study which tile magazine believed constituted the best measures of program quality. Given the subjective nature of the evaluation process which produced these ratings, and the mass media's infatuation with these rankings, this paper examines tire top-rated graduate programs in six social science disciplines based upon criteria established in the Changing Times article. It was found that depanments in each discipline were substantially linked to each other by hiring each other's graduates, and bence, enhancing each other's reputations

Pilgrim Nuclear Power and Cape Cod Bay

Pilgrim Nuclear Power station in Plymouth, MA, is the target of much debate, mostly about how dangerous it is for the people of Cape Cod due to some catastrophic event or radioactive leakage. The chance of either happening is incredibly small, but even still the people of Cape Cod voted to close the plant. The real problem is with the local marine wildlife, which pilgrim, like any other power plant, proves to be a constant threat.https://digitalcommons.wpi.edu/gps-posters/1203/thumbnail.jp

Bovine milk oligosaccharides as anti-adhesives against the respiratory tract pathogen Streptococcus pneumoniae

peer-reviewedStreptococcus pneumoniae is a Gram-positive pathogen, which is regularly found in the upper respiratory tract of healthy individuals. Increased numbers of S. pneumoniae have been observed colonising the upper respiratory tract of children affected by respiratory tract infections. Galβ1-4GlcNAcβ1-3Gal has been previously identified as one of the receptors involved in the adherence and translocation of S. pneumoniae. As this structure is similar to the milk oligosaccharide lacto-N-neoTetraose, many studies have investigated if free milk oligosaccharides can inhibit the adhesion of S. pneumoniae to epithelial cells of the respiratory tract. Here, we demonstrate that bovine oligosaccharides, which were extracted from demineralised whey, using a combination of membrane filtration and chromatography, were capable of reducing S. pneumoniae adhesion to pharynx and lung cells in vitro when tested at physiological concentrations. This study strengthens the potential use of bovine derived milk oligosaccharides as functional ingredients to reduce the incidence of infectious diseases

VLT/XSHOOTER and Subaru/MOIRCS spectroscopy of HUDF.YD3: no evidence for Lyman emission at z = 8.55

We present spectroscopic observations with VLT/XSHOOTER and Subaru/MOIRCS of a relatively bright Y-band drop-out galaxy in the Hubble Ultra Deep Field (HUDF), first selected by Bunker et al., McLure et al. and Bouwens et al. to be a likely z ≈ 8–9 galaxy on the basis of its colours in the Hubble Space Telescope (HST) Advanced Camera for Surveys and Wide Field Camera 3 images. This galaxy, HUDF.YD3 (also known as UDFy-38135539), has been targetted for VLT/SINFONI integral field spectroscopy by Lehnert et al., who published a candidate Lyman α emission line at z = 8.55 from this source. In our independent spectroscopy using two different infrared spectrographs (5 h with VLT/XSHOOTER and 11 h with Subaru/MOIRCS), we are unable to reproduce this line. We do not detect any emission line at the spectral and spatial location reported in Lehnert et al., despite the expected signal in our combined MOIRCS and XSHOOTER data being 5σ. The line emission also seems to be ruled out by the faintness of this object in recently extremely deep F105W (Y band) HST/WFC 3 imaging from HUDF12; the line would fall within this filter and such a galaxy should have been detected at YAB = 28.6 mag (∼20σ) rather than the marginal YAB ≈ 30 mag observed in the Y-band image, >3 times fainter than would be expected if the emission line was real. Hence, it appears highly unlikely that the reported Lyman α line emission at z > 8 is real, meaning that the highest redshift sources for which Lyman α emission has been seen are at z = 6.9-7.2. It is conceivable that Lyman α does not escape galaxies at higher redshifts, where the Gunn–Peterson absorption renders the Universe optically thick to this line. However, deeper spectroscopy on a larger sample of candidate z > 7 galaxies will be needed to test this

No Evidence for Lyman-alpha Emission in Spectroscopy of z > 7 Candidate Galaxies

We present Gemini/GNIRS spectroscopic observations of 4 z-band (z~7) dropout galaxies and VLT/XSHOOTER observations of one z-band dropout and 3 Y-band (z~8-9) dropout galaxies in the Hubble Ultra Deep Field, which were selected with Wide Field Camera 3 imaging on the Hubble Space Telescope. We find no evidence of Lyman-alpha emission with a typical 5-sigma sensitivity of 5X10^-18erg/cm^2/s, and we use the upper limits on Lyman-alpha flux and the broad-band magnitudes to constrain the rest-frame equivalent widths for this line emission. Accounting for incomplete spectral coverage, we survey 3.0 z-band dropouts and 2.9 Y-band dropouts to a Lyman-alpha rest-frame equivalent width limit > 120Ang (for an unresolved emission line); for an equivalent width limit of 50Ang the effective numbers of drop-outs surveyed fall to 1.2 z-band drop-outs and 1.5 Y-band drop-outs. A simple model where the fraction of high rest-frame equivalent width emitters follows the trend seen at z=3-6.5 is inconsistent with our non-detections at z=7-9 at the ~ 1-sigma level for spectrally unresolved lines, which may indicate that a significant neutral HI fraction in the intergalactic medium suppresses the Lyman-alpha line in z-drop and Y-drop galaxies at z > 7.Comment: Accepted for publication in MNRA