The diabatic contour advective semi-Lagrangian model

This article describes a novel algorithmic development extending the contour advective semi-Lagrangian model to include nonconservative effects. The Lagrangian contour representation of finescale tracer fields, such as potential vorticity, allows for conservative, nondiffusive treatment of sharp gradients allowing very high numerical Reynolds numbers. It has been widely employed in accurate geostrophic turbulence and tracer advection simulations. In the present, diabatic version of the model the constraint of conservative dynamics is overcome by including a parallel Eulerian field that absorbs the nonconservative ( diabatic) tendencies. The diabatic buildup in this Eulerian field is limited through regular, controlled transfers of this field to the contour representation. This transfer is done with a fast newly developed contouring algorithm. This model has been implemented for several idealized geometries. In this paper a single-layer doubly periodic geometry is used to demonstrate the validity of the model. The present model converges faster than the analogous semi-Lagrangian models at increased resolutions. At the same nominal spatial resolution the new model is 40 times faster than the analogous semi-Lagrangian model. Results of an orographically forced idealized storm track show nontrivial dependency of storm-track statistics on resolution and on the numerical model employed. If this result is more generally applicable, this may have important consequences for future high-resolution climate modeling.

Muriel Rukeyser: poetry and the body

The human body occupies a central place in Rukeyser’s poetry. Her characters’ physical experiences inspire their search for an artistic form and a holistic vision that reconciles the corporeal and conceptual aspects of their life. My thesis deals with Rukeyser’s reconciliation of disparate aspects of existence through the image of the human body and the practical experiences she underwent in her personal life and incorporated in her poetry. I discuss her poetry of the 1940s, where a tension is observed between the artist’s personal life and her art, which she attempts to resolve by adopting an artistic form that accommodates her quotidian experiences. I study, mainly through her poetry of the 1950s, Rukeyser’s poetic technique in the light of her organicist poetics and the combination of tendencies to coercion and suggestiveness distinguishing her style. I examine her portrayal of the suffering body in her poetry of the 1960s and 1970s. By means of their physical experiences, the ill, her despised and the imprisoned protagonists undergo a process of development whereby they perceive the different aspects of their identity and attempt to broaden perspectives on their situation by reconciling them. I argue that Rukeyser’s engagement with physical encounters and with the poem as an inclusive, organic body enables her to reconcile disparate elements in her poetry, such as her personal life and her art, her individual existence and the public world, as well as the distinct aspects of her characters’ identity. Her vatic outlook, which integrates distinct aspects of experience, is consistent with Merleau-Ponty’s idea of human perception as characterised by the two interdependent positions of immanence and transcendence. Rukeyser’s poetry depicts her physical engagement with quotidian events of her life as a factor of artistic inspiration. These situations constitute shared human experiences that enable her to imagine the links binding her to other people and the world at large. The poet’s personal experiences inspire her search for an artistic form that accommodates them. Her perception of the concrete aspect of her individual existence gains significance when it is linked to social and political issues. Both the private and public are thus seen as interconnected, and they affect the existence of each other while retaining their distinctness.

A behavioral comparison between motorcyclists and a matched group of non-motorcycling car drivers: factors influencing accident risk

Motorcyclists and a matched group of non-motorcycling car drivers were assessed on behavioral measures known to relate to accident involvement. Using a range of laboratory measures, we found that motorcyclists chose faster speeds than the car drivers, overtook more, and pulled into smaller gaps in traffic, though they did not travel any closer to the vehicle in front. The speed and following distance findings were replicated by two further studies involving unobtrusive roadside observation. We suggest that the increased risk-taking behavior of motorcyclists was only likely to account for a small proportion of the difference in accident risk between motorcyclists and car drivers. A second group of motorcyclists was asked to complete the simulator tests as if driving a car. They did not differ from the non-motorcycling car drivers on the risk-taking measures but were better at hazard perception. There were also no differences for sensation seeking, mild social deviance, and attitudes to riding/driving, indicating that the risk-taking tendencies of motorcyclists did not transfer beyond motorcycling, while their hazard perception skill did. (C) 2002 Elsevier Science Ltd. All rights reserved.

Visceral behaviours and leadership: a dark side of boardroom life?

Purpose – Characteristics of leaders whose behaviour is visceral include taking action based on instinct rather than intellect and exhibiting coarse, base and often negative emotions. Despite the challenge of precisely defining the nature of visceral behaviour, the purpose of this paper is to provide insight into this less attractive side of boardroom life. Design/methodology/approach – Following a literature review of the research into the negative behaviour leaders exhibit, the paper highlights four forms of visceral behaviour based on focused and intimate qualitative case studies involving the experiences of those on the receiving end of that behaviour within a boardroom context. Findings – Based on interviews with an international sample of five chief executive officers (CEOs), plus three subordinates with substantial profit and loss responsibility, the study reveals a distinctly human experience from which no one is exempt. The idiosyncratic nature of the visceral behaviour experienced resulted in each study participant's unique experience. The authors conclude that leaders need to adopt specific measures in order to control and reduce the darker human tendencies. Research limitations/implications – The experiences of study participants are presented in four case studies, providing insight into their experiences whilst also protecting their identity. The study participants were drawn from a sample of companies operating globally within a single sector of the manufacturing industry. The concepts the authors present require validating in other organisations with different demographic profiles. Originality/value – The paper presents a model based on two dimensions – choice and level of mastery – that provides the reader with insight into the forms of visceral behaviour to which leaders succumb. Insight enables us to offer managers strategic suggestions to guard against visceral behaviour and assist them in mitigating its worst aspects, in both those with whom they work and themselves.

Combining satellite observations and reanalysis energy transports to estimate global net surface energy fluxes 1985-2012

Two methods are developed to estimate net surface energy fluxes based upon satellite-based reconstructions of radiative fluxes at the top of atmosphere and the atmospheric energy tendencies and transports from the ERA-Interim reanalysis. Method 1 applies the mass adjusted energy divergence from ERA-Interim while method 2 estimates energy divergence based upon the net energy difference at the top of atmosphere and the surface from ERA-Interim. To optimise the surface flux and its variability over ocean, the divergences over land are constrained to match the monthly area mean surface net energy flux variability derived from a simple relationship between the surface net energy flux and the surface temperature change. The energy divergences over the oceans are then adjusted to remove an unphysical residual global mean atmospheric energy divergence. The estimated net surface energy fluxes are compared with other data sets from reanalysis and atmospheric model simulations. The spatial correlation coefficients of multi-annual means between the estimations made here and other data sets are all around 0.9. There are good agreements in area mean anomaly variability over the global ocean, but discrepancies in the trend over the eastern Pacific are apparent.

My generation(s): cycles, branding and renewal in E4’s 'Skins'

In an era of fragmenting audience and diversified viewing platforms, youth television needs to move fast and make a lot of noise in order to capture and maintain the attention of the teenage viewer. British ensemble youth drama Skins (E4, 2007-2013) calls attention to itself with its high doses of drugs, chaotic parties and casual attitudes towards sexuality. It also moves quickly, shedding its cast every two seasons as they graduate from school, then renewing itself with a fresh generation of 16 year old characters - three cycles in total. This essay will explore the challenges of maintaining audience connections whilst resetting the narrative clock with each cycle. I suggest that the development of the Skins brand was key to the programme’s success. Branding is particularly important for an audience demographic who increasingly consume their television outside of broadcast flow and essential for a programme which renews its cast every two years. The Skins brand operate as a framework, as the central audience draw, have the strength to maintain audience connections when it ‘graduates’ those characters they identify with at the close of each cycle and starts again from scratch. This essay will explore how the Skins brand constructs a cohesive identity across its multiple generations, yet also consider how the cyclic form poses challenges for the programme’s representations and narratives. This cyclic form allows Skins to repeatedly reach out to a new audience who comes of age alongside each new generation and to reflect shifts in British youth culture. Thus Skins remains ever-youthful, seeking to maintain an at times painfully hip identity. Yet the programme has a somewhat schizophrenic identity, torn between its roots in British realist drama and surrealist comedy and an escapist aspirational glamour that shows the influence of US Teen TV. This combination results in a tendency towards a heightened melodrama at odds with Skins claims for authenticity - its much vaunted teenage advisors and young writers - with the cyclic structure serving to amplify the programme’s excessive tendencies. Each cycle wrestles with a need for continuity and familiarity - partly maintained through brand, aesthetic and setting - yet a desire for freshness and originality, to assert difference from what has gone before. I suggest that the inevitable need for each cycle to ‘top’ what has gone before results in a move away from character-based intimacy and the everyday to high-stakes drama and violence which sits uncomfortably within British youth television.

Antoine de La Sale's 'La Sale': the cannonball and the prince's head

The elderly tutor La Sale's didactic treatise for his charges (dated 1451) includes an eye-witness account of the siege of Anjou-held Naples by the Aragonese in 1438. It narrates the accidental death (or miracle, depending on the perspective of the chroniclers) of the infante Pedro of Castille, brother of King Alfonso the Magnanimous of Aragon. This article explores how "La Sale", an adapted version of the Middle French translation of Valerius Maximus's 'Facta et dicta memorabilia', frames and skews the anecdote towards an exploration of the reliability and authority of the tutor-narrator.

Fetal programming effects of testosterone on the reward system and behavioral approach tendencies in humans

BACKGROUND: Sex differences are present in many neuropsychiatric conditions that affect emotion and approach-avoidance behavior. One potential mechanism underlying such observations is testosterone in early development. Although much is known about the effects of testosterone in adolescence and adulthood, little is known in humans about how testosterone in fetal development influences later neural sensitivity to valenced facial cues and approach-avoidance behavioral tendencies. METHODS: With functional magnetic resonance imaging we scanned 25 8-11-year-old children while viewing happy, fear, neutral, or scrambled faces. Fetal testosterone (FT) was measured via amniotic fluid sampled between 13 and 20 weeks gestation. Behavioral approach-avoidance tendencies were measured via parental report on the Sensitivity to Punishment and Sensitivity to Rewards questionnaire. RESULTS: Increasing FT predicted enhanced selectivity for positive compared with negatively valenced facial cues in reward-related regions such as caudate, putamen, and nucleus accumbens but not the amygdala. Statistical mediation analyses showed that increasing FT predicts increased behavioral approach tendencies by biasing caudate, putamen, and nucleus accumbens but not amygdala to be more responsive to positive compared with negatively valenced cues. In contrast, FT was not predictive of behavioral avoidance tendencies, either through direct or neurally mediated paths. CONCLUSIONS: This work suggests that testosterone in humans acts as a fetal programming mechanism on the reward system and influences behavioral approach tendencies later in life. As a mechanism influencing atypical development, FT might be important across a range of neuropsychiatric conditions that asymmetrically affect the sexes, the reward system, emotion processing, and approach behavior.

A groove-ploughing theory for the production of mega-scale glacial lineations, and implications for ice-stream mechanics

Mega-scale glacial lineations (MSGLs) are longitudinally aligned corrugations (ridge-groove structures 6-100 km long) in sediment produced subglacially. They are indicators of fast flow and a common signature of ice-stream beds. We develop a qualitative theory that accounts for their formation, and use numerical modelling, and observations of ice-stream beds to provide supporting evidence. Ice in contact with a rough (scale of 10-10(3) m) bedrock surface will mimic the form of the bed. Because of flow acceleration and convergence in ice-stream onset zones, the ice-base roughness elements experience transverse strain, transforming them from irregular bumps into longitudinally aligned keels of ice protruding downwards. Where such keels slide across a soft sedimentary bed, they plough through the sediments, carving elongate grooves, and deforming material up into intervening ridges. This explains MSGLs and has important implications for ice-stream mechanics. Groove ploughing provides the means to acquire new lubricating sediment and to transport large volumes of it downstream. Keels may provide basal drag in the force budget of ice streams, thereby playing a role in flow regulation and stability We speculate that groove ploughing permits significant ice-stream widening, thus facilitating high-magnitude ice discharge.

Studentification and 'apprentice' gentrifiers within Britain's provincial towns and cities: extending the meaning of gentrification

This paper focuses on processes of studentification, and explores the link between higher education students and contemporary provincial gentrification. The paper provides two main, interconnected, contributions to advance debates on gentrification. First, the discussion appeals for wider temporal analyses of the lifecourses of gentrifiers to trace the formation and reconfiguration of the cultural and residential predilections of gentrifiers across time and space. With this in mind, it is argued that there is a need to rethink the role of students within the constraints of third-wave gentrification, and to consider how 'student experiences' may influence the current and future residential geographies of young gentrifiers within provincial urban locations. Drawing upon recent studies of studentification, it is asserted that this profound expression of urban change is indicative of gentrification. Second, the paper advances Clark's recent call to extend the term gentrification to embrace the wider dominant hallmarks and tendencies of urban transformations. Controversially, in light of a deepening institutionalisation of gentrification, we contend that gentrification can be most effectively employed at a revised conceptual level to act as a referent of the common outcomes of a breadth of processes of change.

The Dubawnt Lake palaeo-ice stream: evidence for dynamic ics sheet behaviour on the Canadian Shield and insights regarding the controls on ice-stream location and vigour

We report evidence for a major ice stream that operated over the northwestern Canadian Shield in the Keewatin Sector of the Laurentide Ice Sheet during the last deglaciation 9000-8200 (uncalibrated) yr BP. It is reconstructed at 450 km in length, 140 km in width, and had an estimated catchment area of 190000 km. Mapping from satellite imagery reveals a suite of bedforms ('flow-set') characterized by a highly convergent onset zone, abrupt lateral margins, and where flow was presumed to have been fastest, a remarkably coherent pattern of mega-scale glacial lineations with lengths approaching 13 km and elongation ratios in excess of 40:1. Spatial variations in bedform elongation within the flow-set match the expected velocity field of a terrestrial ice stream. The flow pattern does not appear to be steered by topography and its location on the hard bedrock of the Canadian Shield is surprising. A soft sedimentary basin may have influenced ice-stream activity by lubricating the bed over the downstream crystalline bedrock, but it is unlikely that it operated over a pervasively deforming till layer. The location of the ice stream challenges the view that they only arise in deep bedrock troughs or over thick deposits of 'soft' fine-grained sediments. We speculate that fast ice flow may have been triggered when a steep ice sheet surface gradient with high driving stresses contacted a proglacial lake. An increase in velocity through calving could have propagated fast ice flow upstream (in the vicinity of the Keewatin Ice Divide) through a series of thermomechanical feedback mechanisms. It exerted a considerable impact on the Laurentide Ice Sheet, forcing the demise of one of the last major ice centres.

The omega equation and potential vorticity

Two fundamental perspectives on the dynamics of midlatitude weather systems are provided by potential vorticity (PV) and the omega equation. The aim of this paper is to investigate the link between the two perspectives, which has so far received very little attention in the meteorological literature. It also aims to give a quantitative basis for discussion of quasi-geostrophic vertical motion in terms of components associated with system movement, maintaining a constant thermal structure, and with the development of that structure. The former links with the isentropic relative-flow analysis technique. Viewed in a moving frame of reference, the measured development of a system depends on the velocity of that frame of reference. The requirement that the development should be a minimum provides a quantitative method for determining the optimum system velocity. The component of vertical velocity associated with development is shown to satisfy an omega equation with forcing determined from the relative advection of interior PV and boundary temperature. The analysis carries through in the presence of diabatic heating provided the omega equation forcing is based on the interior PV and boundary thermal tendencies, including the heating effect. The analysis is shown to be possible also at the level of the semi-geostrophic approximation. The analysis technique is applied to a number of idealized problems that can be considered to be building blocks for midlatitude synoptic-scale dynamics. They focus on the influences of interior PV, boundary temperature, an interior boundary, baroclinic instability associated with two boundaries, and also diabatic heating. In each case, insights yielded by the new perspective are sought into the dynamical behaviour, especially that related to vertical motion. Copyright © 2003 Royal Meteorological Society

The diurnal cycle of convection and atmospheric tides in an aquaplanet

The diurnal cycle of tropical convection and its relationship to the atmospheric tides is investigated using an aquaplanet GCM. The diurnal and semidiurnal harmonics of precipitation are both found to contribute significantly to the total diurnal variability of precipitation in the model, which is broadly consistent with observations of the diurnal cycle of convection over the open ocean. The semidiurnal tide is found to be the dominant forcing for the semidiurnal harmonic of precipitation. In contrast the diurnal tide plays only a small role in forcing the diurnal harmonic of precipitation, which is dominated by the variations in shortwave and longwave heating. In both the diurnal and semidiurnal harmonics, the feedback onto the convection by the humidity tendencies due to the convection is found to be important in determining the phase of the harmonics. Further experiments show that the diurnal cycle of precipitation is sensitive to the choice of closure in the convection scheme. While the surface pressure signal of the simulated atmospheric tides in the model agree well with both theory and observations in their magnitude and phase, sensitivity experiments suggest that the role of the stratospheric ozone in forcing the semidiurnal tide is much reduced compared to theoretical predictions. Furthermore, the influence of the cloud radiative effects seems small. It is suggested that the radiative heating profile in the troposphere, associated primarily with the water vapor distribution, is more important than previously thought for driving the semidiurnal tide. However, this result may be sensitive to the vertical resolution and extent of the model.

The cumulus-capped boundary layer. I: Modelling transports in the cloud layer

Scalar-flux budgets have been obtained from large-eddy simulations (LESs) of the cumulus-capped boundary layer. Parametrizations of the terms in the budgets are discussed, and two parametrizations for the transport term in the cloud layer are proposed. It is shown that these lead to two models for scalar transports by shallow cumulus convection. One is equivalent to the subsidence detrainment form of convective tendencies obtained from mass-flux parametrizations of cumulus convection. The second is a flux-gradient relationship that is similar in form to the non-local parametrizations of turbulent transports in the dry-convective boundary layer. Using the fluxes of liquid-water potential temperature and total water content from the LES, it is shown that both models are reasonable diagnostic relations between fluxes and the vertical gradients of the mean fields. The LESs used in this study are for steady-state convection and it is possible to treat the fluxes of conserved thermodynamic variables as independent, and ignore the effects of condensation. It is argued that a parametrization of cumulus transports in a model of the cumulus-capped boundary layer should also include an explicit representation of condensation. A simple parametrization of the liquid-water flux in terms of conserved variables is also derived.