Critical properties of a continuous family of XY noncollinear magnets

Monte Carlo methods are used to study a family of three dimensional XY frustrated models interpolating continuously between the stacked triangular antiferromagnets and a variant of this model for which a local rigidity constraint is imposed. Our study leads us to conclude that generically weak first order behavior occurs in this family of models in agreement with a recent nonperturbative renormalization group description of frustrated magnets.Comment: 5 pages, 3 figures, minor changes, published versio

Influence of Increased Options on Performance Generalization Across Two Variations of the Monty Hall Dilemma

The Monty Hall dilemma (MHD) is a probability puzzle at which humans consistently fail to adopt the optimal winning strategy. The participant chooses between three identical doors, behind one of which is a valuable prize. After the participant makes their initial decision, the host reveals that there is nothing behind one of the two remaining doors, then asks the participant if they would like to stay with their originally selected door or switch to the remaining unopened door. The optimal choice is to switch to the previously unchosen door, which increases the probability of winning from 33% to 67%. Despite this basic solution, humans repeatedly perform suboptimally. Previous attempts to improve performance by increasing the number of available doors have been successful (Burns & Weith, 2004; Franko-Watkins et al., 2003; Saenen et al., 2015; Stibel et al., 2009; Watzek et al., 2018). However, prior studies that examined whether this improved performance could generalize to different contexts have been inconclusive (Franko-Watkins et al., 2003; Watzek et al., 2018). To examine whether human performance can generalize across two computerized variations of the MHD, the present study explored how previous experience involving trials presented with eight options affects switching percentages in subsequent trials with three options. The results failed to replicate findings from previous studies, which demonstrated that rates of switching increased as a function of more available options. Implications of and explanations for this replication failure are discussed. Further exploration of the MHD is needed before definitive conclusions can be made regarding humans’ ability to generalize knowledge between task variations

RASS-SDSS Galaxy Cluster Survey. VI. The dependence of the cluster SFR on the cluster global properties

Using a subsample of 79 nearby clusters from the RASS-SDSS galaxy cluster catalogue of Popesso et al. (2005a), we perform a regression analysis between the cluster integrated star formation rate (Sigma_SFR) the cluster total stellar mass (M_star), the fractions of star forming (f_SF) and blue (f_b) galaxies and other cluster global properties, namely its richness (N_gal, i.e. the total number of cluster members within the cluster virial radius), velocity dispersion (sigma_v), virial mass (M_200), and X-ray luminosity (L_X). All cluster global quantities are corrected for projection effects before the analysis. Galaxy SFRs and stellar masses are taken from the catalog of Brinchmann et al. (2004), which is based on SDSS spectra. We only consider galaxies with M_r <= -20.25 in our analysis, and exclude AGNs. We find that both Sigma_SFR and M_star are correlated with all the cluster global quantities. A partial correlation analysis show that all the correlations are induced by the fundamental one between Sigma_SFR and N_gal, hence there is no evidence that the cluster properties affect the mean SFR or M_star per galaxy. The relations between Sigma_SFR and M_star, on one side, and both N_gal and M_200, on the other side, are linear, i.e. we see no evidence that different clusters have different SFR or different M_star per galaxy and per unit mass. The fraction f_SF does not depend on any cluster property considered, while f_b does depend on L_X. We note that a significant fraction of star-forming cluster galaxies are red (~25% of the whole cluster galaxy population). We conclude that the global cluster properties are unable to affect the SF properties of cluster galaxies, but the presence of the X-ray luminous intra-cluster medium can affect their colors, perhaps through the ram-pressure stripping mechanism.Comment: 14 pages, 12 figures, accepted for publication on A&A; corrected coefficient in Tab.

Applications of CFD and visualization techniques

In this paper, three applications are presented to illustrate current techniques for flow calculation and visualization. The first two applications use a commercial computational fluid dynamics (CFD) code, FLUENT, performed on a Cray Y-MP. The results are animated with the aid of data visualization software, apE. The third application simulates a particulate deposition pattern using techniques inspired by developments in nonlinear dynamical systems. These computations were performed on personal computers

Damage spreading in two dimensional geometrically frustrated lattices: the triangular and kagome anistropic Heisenberg model

The technique of damage spreading is used to study the phase diagram of the easy axis anisotropic Heisenberg antiferromagnet on two geometrically frustrated lattices. The triangular and kagome systems are built up from triangular units that either share edges or corners respectively. The triangular lattice undergoes two sequential Kosterlitz-Thouless transitions while the kagome lattice undergoes a glassy transition. In both cases, the phase boundaries obtained using damage spreading are in good agreement with those obtained from equilibrium Monte Carlo simulations.Comment: 7 pages, 4 figure

VELO Module Production â Pre-Assembly Hybrid Testing

This note describes in detail the procedures used in the reception, handling, testing and storage of Hybrids for the LHCb VELO detector modules

Community Land Trusts, affordable housing and community organising in low-income neighbourhoods

Community Land Trusts (CLTs) offer a community-led response to housing problems and can provide affordable housing for low-income residents. Generally the academic work on CLTs remains underdeveloped, particularly in the UK, although some argue that they can be an efficient way in which to manage scarce resources while others have noted that CLTs can provide a focal point for community resistance. In this article we provide evidence on two active CLTs in inner urban areas in major US cities, New York and Boston. In Cooper Square, Lower East Side Manhattan and Dudley Street, south Boston, we see the adoption of different approaches to development suggesting that we should speak of models of CLTs rather than assuming a single operational approach. The cases we present indicate both radical and reformist responses to the state and market provision of housing and neighbourhood sustainability. They also suggest community activism can prove to be significant in securing land and the development of the CLT

Community land trusts: A radical or reformist response to the housing question today?

Community Land Trusts (CLTs) can be a focal point of community organization in defence of neighbourhood space and in seeking to push back against powerful developers. Simultaneously, we also see CLTs that represent a reformist desire for self-help and petite bourgeois claims on home ownership. Through a study of three working class neighbourhoods, one each in Manhattan and Boston and the other in Liverpool, UK, we see evidence of radical agitation, reformist politicization and technocratic authority over the deployment of resources and the management of land and housing. The CLT is shown as a means by which communities become politicized, operating as a site of resistance to what Harvey would refer to as 'surplus absorption' through inner urban transformation. Yet, if as Engels suggests, the abolition of the capitalist mode of production is the only way to address inequality driven by private property rights and developer interests, he may also have argued that, while CLTs begin as radical instruments, their impact on the housing question will always remain reformist in character

Spin Stiffness of Stacked Triangular Antiferromagnets

We study the spin stiffness of stacked triangular antiferromagnets using both heat bath and broad histogram Monte Carlo methods. Our results are consistent with a continuous transition belonging to the chiral universality class first proposed by Kawamura.Comment: 5 pages, 7 figure