The comfort, energy and health implications of London’s urban heat island

The urban heat island (UHI) is a well-known effect of urbanisation and is particularly important in world megacities. Overheating in such cities is expected to be exacerbated in the future as a result of further urban growth and climate change. Demonstrating and quantifying the impact of individual design interventions on the UHI is currently difficult using available software tools. The tools developed in the LUCID (‘The Development of a Local Urban Climate Model and its Application to the Intelligent Design of Cities’) research project will enable the related impacts to be better understood, quantified and addressed. This article summarises the relevant literature and reports on the ongoing work of the project.

Compression of polyelectrolyte brushes in a salt-free theta solvent

This paper examines the normal force between two opposing polyelectrolyte brushes and the interpenetration of their chains that is responsible for sliding friction. It focuses on the special case of semi-dilute brushes in a salt-free theta solvent, for which Zhulina and Borisov [J. Chem. Phys., {\bf 107}, 5952, (1997)] have derived analytical predictions using the classical strong-stretching theory (SST) introduced by Semenov and developed by Milner, Witten and Cates. Interestingly, the SST predicts that the brushes contract maintaining a polymer-free gap as they are compressed together, which provides an explanation for the ultra-low frictional forces observed in experiment. We examine the degree to which the SST predictions are affected by chain fluctuations by employing self-consistent field theory (SCFT). While the normal force is relatively unaffected, fluctuations are found to have a strong impact on brush interpenetration. Even still, the contraction of the brushes does significantly prolong the onset of interpenetration, implying that a sizeable normal force can be achieved before the sliding friction becomes significant.

Making robust policy decision using global biodiversity indicators

In order to influence global policy effectively, conservation scientists need to be able to provide robust predictions of the impact of alternative policies on biodiversity and measure progress towards goals using reliable indicators. We present a framework for using biodiversity indicators predictively to inform policy choices at a global level. The approach is illustrated with two case studies in which we project forwards the impacts of feasible policies on trends in biodiversity and in relevant indicators. The policies are based on targets agreed at the Convention on Biological Diversity (CBD) meeting in Nagoya in October 2010. The first case study compares protected area policies for African mammals, assessed using the Red List Index; the second example uses the Living Planet Index to assess the impact of a complete halt, versus a reduction, in bottom trawling. In the protected areas example, we find that the indicator can aid in decision-making because it is able to differentiate between the impacts of the different policies. In the bottom trawling example, the indicator exhibits some counter-intuitive behaviour, due to over-representation of some taxonomic and functional groups in the indicator, and contrasting impacts of the policies on different groups caused by trophic interactions. Our results support the need for further research on how to use predictive models and indicators to credibly track trends and inform policy. To be useful and relevant, scientists must make testable predictions about the impact of global policy on biodiversity to ensure that targets such as those set at Nagoya catalyse effective and measurable change.

'he perceives himself as a caterpillar […]' constructions of the disabled subject in the critical response to Alfred Hitchcock's 'Rear Window'

This chapter focuses on critical responses to Alfred Hitchcock’s Rear Window, especially their construction of disability. The suggestion is that such criticism takes the disabled body to be both necessary and superfluous to the meaning of the film, a difficulty that, I argue, can be read more widely within film theory. Ever since Christian Metz’s ‘the Imaginary Signifier’, the condition of being ‘bound to a wheelchair’ is understood to have a resonance for theories of film spectatorship, but only ever in a sense that does away with the wheelchair as a mark of difference.

Large deviations of Rouse polymer chain: first passage problem

The purpose of this paper is to investigate several analytical methods of solving first passage (FP) problem for the Rouse model, a simplest model of a polymer chain. We show that this problem has to be treated as a multi-dimensional Kramers' problem, which presents rich and unexpected behavior. We first perform direct and forward-flux sampling (FFS) simulations, and measure the mean first-passage time $\tau(z)$ for the free end to reach a certain distance $z$ away from the origin. The results show that the mean FP time is getting faster if the Rouse chain is represented by more beads. Two scaling regimes of $\tau(z)$ are observed, with transition between them varying as a function of chain length. We use these simulations results to test two theoretical approaches. One is a well known asymptotic theory valid in the limit of zero temperature. We show that this limit corresponds to fully extended chain when each chain segment is stretched, which is not particularly realistic. A new theory based on the well known Freidlin-Wentzell theory is proposed, where dynamics is projected onto the minimal action path. The new theory predicts both scaling regimes correctly, but fails to get the correct numerical prefactor in the first regime. Combining our theory with the FFS simulations lead us to a simple analytical expression valid for all extensions and chain lengths. One of the applications of polymer FP problem occurs in the context of branched polymer rheology. In this paper, we consider the arm-retraction mechanism in the tube model, which maps exactly on the model we have solved. The results are compared to the Milner-McLeish theory without constraint release, which is found to overestimate FP time by a factor of 10 or more.

Coloso fragmentado: la agenda “interméstica” y la política exterior latinoamericana

Los asuntos “intermésticos”, como el comercio, la migración y el narcotráfico, tienen un gran peso en las relaciones contemporáneas entre Estados Unidos y América Latina y son de suma importancia para los estados latinoamericanos y del Caribe. Pero, pese a su trascendencia para los líderes y las sociedades de Latinoamérica, el éxito que han tenido los diplomáticos del continente en influir sobre la política estadounidense en estos temas ha sido aún menor que en otras esferas. Esto se debe, al menos en parte, a las dinámicas que los asuntos intermésticos generan en el proceso de la política exterior de Estados Unidos. Si bien dichas dinámicas han sido ampliamente estudiadas, se ha prestado menos atención a cómo inciden en la política exterior de América Latina y el Caribe hacia Estados Unidos. A partir de los trabajos de Putnam, Milner y Tsebelis, entre otros, este artículo sostiene que los asuntos intermésticos enfrentan más actores con capacidad de veto y tienen menos “conjuntos ganadores” (win-sets) que los asuntos de política exterior tradicionales, lo que dificulta aún más los intentos por influir en las políticas estadounidenses. Esta tesis se examina tomando como ejemplo el caso de la disputa entre Estados Unidos y México por el cruce fronterizo de camiones y los veinte años que el gobierno mexicano tuvo que luchar contra funcionarios y grupos de interés estadounidenses para lograr que aquel país cumpliera con lo dispuesto en el TLCAN. Luego de examinar brevemente otros asuntos similares, el artículo concluye que los asuntos intermésticos exigen estrategias diplomáticas diferentes por parte de los legisladores latinoamericanos.

The three faces of bounded reliability: Alfred Chandler and the micro-foundations of management theory

Alfred Chandler, the celebrated business historian, provided detailed descriptions of the reasons for failed human commitments and the managerial tools needed to prevent/remediate such failings in the context of large business firms. Chandler's historical narrative identifies three distinct “faces” of bounded reliability—opportunism, benevolent preference reversal, and identity-based discordance—as the main drivers of commitment failure. Adopting bounded reliability (BRel) as a micro-foundation in management studies will raise the quality and relevance of scholarly recommendations to improve managerial decision making and action, because analysis of BRel challenges closely mirrors the real-world problems facing practicing managers.

Population genetic analysis of large sequence polymorphisms in Plasmodium falciparum blood-stage antigens

Plasmodium falciparum, the causative agent of human malaria, invades host erythrocytes using several proteins on the surface of the invasive merozoite, which have been proposed as potential vaccine candidates. Members of the multi-gene PfRh family are surface antigens that have been shown to play a central role in directing merozoites to alternative erythrocyte receptors for invasion. Recently, we identified a large structural polymorphism, a 0.58 Kb deletion, in the C-terminal region of the PfRh2b gene, present at a high frequency in parasite populations from Senegal. We hypothesize that this region is a target of humoral immunity. Here, by analyzing 371 P. falciparum isolates we show that this major allele is present at varying frequencies in different populations within Senegal, Africa, and throughout the world. For allelic dimorphisms in the asexual stage antigens, Msp-2 and EBA-175, we find minimal geographic differentiation among parasite populations from Senegal and other African localities, suggesting extensive gene flow among these populations and/or immune-mediated frequency-dependent balancing selection. In contrast, we observe a higher level of inter-population divergence (as measured by F(st)) for the PfRh2b deletion, similar to that observed for SNPs from the sexual stage Pfs45/48 loci, which is postulated to be under directional selection. We confirm that the region containing the PfRh2b polymorphism is a target of humoral immune responses by demonstrating antibody reactivity of endemic sera. Our analysis of inter-population divergence suggests that in contrast to the large allelic dimorphisms in EBA-175 and Msp-2, the presence or absence of the large PfRh2b deletion may not elicit frequency-dependent immune selection, but may be under positive immune selection, having important implications for the development of these proteins as vaccine candidates. (C) 2009 Elsevier B.V. All rights reserved.