873 resultados para SAW


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Purpose. Drivers adopt smaller safety margins when pulling out in front of motorcycles compared with cars. This could partly account for why the most common motorcycle/car accident involves a car violating a motorcyclist's right of way. One possible explanation is the size-arrival effect in which smaller objects are perceived to arrive later than larger objects. That is, drivers may estimate the time to arrival of motorcycles to be later than cars because motorcycles are smaller. Methods. We investigated arrival time judgments using a temporal occlusion paradigm. Drivers recruited from the student population (n = 28 and n = 33) saw video footage of oncoming vehicles and had to press a response button when they judged that vehicles would reach them. Results. In experiment 1, the time to arrival of motorcycles was estimated to be significantly later than larger vehicles (a car and a van) for different approach speeds and viewing times. In experiment 2, we investigated an alternative explanation to the size-arrival effect: that the smaller size of motorcycles places them below the threshold needed for observers to make an accurate time to arrival judgment using tau. We found that the motorcycle/car difference in arrival time estimates was maintained for very short occlusion durations when tau could be estimated for both motorcycles and cars. Conclusions. Results are consistent with the size-arrival effect and are inconsistent with the tau threshold explanation. Drivers estimate motorcycles will reach them later than cars across a range of conditions. This could have safety implications.

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This study examined whether individual differences in perception of the quality of professional support available at a time of stress may be associated with security of attachment. We developed a new measure of parents' perceptions of emotional and practical support provided by a wide range of professionals involved in the treatment of infants with cleft lip. it showed good internal reliability and stability over 4 months. Mothers of 102 infants with cleft lip, with or without cleft palate, completed the measure at 2 and 6 months, together with the Parental Bonding Instrument and the General Health Questionnaire. Mean scores reflecting how much they could trust or talk frankly, or share their worst fears, with professionals, and the extent to which they saw them as a source of useful information or practical help, were lower among mothers with recollections of low maternal care in childhood, or high control. This was the case at 2 and 6 months, and there were some indications of an increasing contribution of low maternal care from 2 to 6 months. The associations were not explained by current depression. Further research is needed to clarify the role of attachment processes in parents' responses to serious medical conditions in their children, and into the implications for the way professionals in paediatric services provide support.

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Recent theories propose that semantic representation and sensorimotor processing have a common substrate via simulation. We tested the prediction that comprehension interacts with perception, using a standard psychophysics methodology.While passively listening to verbs that referred to upward or downward motion, and to control verbs that did not refer to motion, 20 subjects performed a motion-detection task, indicating whether or not they saw motion in visual stimuli containing threshold levels of coherent vertical motion. A signal detection analysis revealed that when verbs were directionally incongruent with the motion signal, perceptual sensitivity was impaired. Word comprehension also affected decision criteria and reaction times, but in different ways. The results are discussed with reference to existing explanations of embodied processing and the potential of psychophysical methods for assessing interactions between language and perception.

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Eddy-covariance measurements of carbon dioxide fluxes were taken semi-continuously between October 2006 and May 2008 at 190 m height in central London (UK) to quantify emissions and study their controls. Inner London, with a population of 8.2 million (~5000 inhabitants per km2) is heavily built up with 8% vegetation cover within the central boroughs. CO2 emissions were found to be mainly controlled by fossil fuel combustion (e.g. traffic, commercial and domestic heating). The measurement period allowed investigation of both diurnal patterns and seasonal trends. Diurnal averages of CO2 fluxes were found to be highly correlated to traffic. However changes in heating-related natural gas consumption and, to a lesser extent, photosynthetic activity that controlled the seasonal variability. Despite measurements being taken at ca. 22 times the mean building height, coupling with street level was adequate, especially during daytime. Night-time saw a higher occurrence of stable or neutral stratification, especially in autumn and winter, which resulted in data loss in post-processing. No significant difference was found between the annual estimate of net exchange of CO2 for the expected measurement footprint and the values derived from the National Atmospheric Emissions Inventory (NAEI), with daytime fluxes differing by only 3%. This agreement with NAEI data also supported the use of the simple flux footprint model which was applied to the London site; this also suggests that individual roughness elements did not significantly affect the measurements due to the large ratio of measurement height to mean building height.

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In negotiating commercial leases, many landlords and tenants employ property agents (brokers) to act on their behalf; typically these people are chartered surveyors. The aim of this paper is to explore the role that these brokers play in the shaping of commercial leases in the context of the current debate in the UK on upward only rent reviews. This role can be described using agency theory and the theories of professionalism. These provide expectations of behaviour which show inherent tensions between the role of agent and professional, particularly regarding the use of knowledge, autonomy and the obligation to the public interest. The parties to eleven recent lease transactions were interviewed to see if the brokers conformed to the expectations of agency theory or professionalism. Brokers that acted for industrial and office tenants behaved as professionals in using their expertise to determine lease structures. However, those acting for landlords and retail tenants simply followed instructions and behaved as conduits for their clients, a role more usually associated with that of an agent within the principal-agent relationship. None of the landlords’ brokers saw themselves as having responsibilities beyond their clients and so they were not promoting the discussion of alternatives to the UORR. The evidence from these case studies suggests that agents are not professionals; to behave entirely as an agent is to contradict the essential characteristics of a professional. While brokers cannot be held entirely responsible for the lack of movement on the UORR, by adopting predominantly agent roles then they must take some of the blame. However, behind this may be a much larger issue that needs to be explored; the institutional pressures that lead to professionals behaving in this way.

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This article discusses emotion as a strategy of political agency in post-Thatcherite documentary theatre. The 1990s saw a renaissance in theatre writing based in directness and immediacy but based in two quite different forms of drama, In-Yer-Face theatre and fact-based drama. There are clear distinctions between these forms: the new brutalist writing was aggressively provocative; documentary theatre engaged the audience by revealing an urgent truth. Both claimed a kind of realism that confronted actuality, be that of situation or experience, through forms of theatre that cultivated emotional engagement. In-Yer-Face theatre used emotional shock to penetrate the numb cynicism that its creators perceived. Documentary theatre used observation and the cultivation of sympathy to enlist its audience in a shared understanding of what was hidden, not understood or not noticed. The article analyses the functioning of emotional enlistment to engage the audience politically in two examples of documentary theatre, Black Watch and Guantanamo

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This article uses census data for Berkshire to argue that large-scale counterurbanization began much earlier than is generally recognized in some parts of southern England. This was not just movement down the urban hierarchy, which as Pooley and Turnbull have demonstrated was a long-term feature of England’s settlement system, but in some cases at least amenity-driven migration to rural areas of the kind increasingly recognized as a core component of recent counterurbanization. Despite a reduction of acreage Berkshire’s rural districts saw a 54% rise in population between 1901 and 1951. The sub-regional pattern of growth is assessed to gauge whether ‘clean break’ migration to the remote west of the county (which remained effectively out of commuting range from London throughout the period) was taking place, or whether counterurbanization was confined to the more accessible eastern districts. However, whilst population did increase in both west and east, it was in fact the central districts that grew most impressively. Three case study parishes are investigated in order to gauge the nature and consequences of counterurbanization at a local level. Professional and business migrants figure prominently, seeking to preserve and promote the rural attributes of their new communities, without however cutting their ties to urban centres. It is argued that migration to rural Berkshire in the first half of the twentieth century cannot adequately be described either as a form of extended suburbanization or an anti-metropolitan ‘clean break’. Rather, early counterurbanization marks the first stage on the long road to a post-productivist countryside, in which countryside becomes detached from agriculture, there is socio-economic convergence between town and country, and the ‘rural’ increasingly becomes defined by landscape and identity rather than economic function.

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The present study sets out to examine motivation to learn English by Chinese research students in an informal setting. Data were collected, using semi-structured interviews, from four research students at two points in time during their first year in the UK. The main findings are: they believed that learning English was important; their main goal orientations were instrumental and extrinsic; they set learning goals and persisted to attain them; they valued their current learning environment in general and saw it as supportive of their goals; they held both positive and negative attitudes towards the British, which had differential effects on their motivation; their self-perceived support seemed to have a positive impact on their motivation and the development of self-confidence; they tended to attribute their success to stable causes such as the environment and failure to unstable but controllable causes such as effort. It is concluded that qualitative data of this kind may complement insights from quantitative research. Implications for target country institutions in the provision of support are discussed.

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The incorporation of ekphrastic evocations of photographs into fictional works is a growing trend charted by (mostly) literary and (occasionally) art critics interested in the effect of their inclusion in a narrative. What has emerged as a veritable affinity of photography with literature has produced a fertile interdisciplinary critical discourse around areas of intersection between visual and verbal. With regard to short fiction, the photograph is often subject to investigation as analogy, the photograph and the short story being considered metonymically related with regard to form and effect. This notion of a structural equivalence between short story and photograph is one stressed by author/photographer Julio Cortàzar, concerned to highlight the quality of intensity he ascribes to both forms, which he saw as ‘cutting out a piece of reality’ in order to ‘breaking out’ into a wider one. Given Annie Saumont’s oft-cited admiration of Cortàzar’s work it is unsurprising that in her own writing – of stories themselves often classed, in their elliptical density, as verbal snapshots – she should take an interest in photographs and/or photographers. This article seeks to explore and analyse different values Saumont ascribes to what was paradoxically described by Barthes as ‘invisible’, in that what we see when viewing a photograph is, (often treacherously), ‘ pas elle qu’on voit’: never, or never solely, the actual object itself …

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Writers on military matters from the 14th century until the late 18th century either regretted the decadence of their times compared with Antiquity, or they saw no great change in military affairs since Antiquity. Few saw a revolutionary change ushered in by gunpowder, although this number increased since the great "querelle" about the Ancients and the Moderns under Louis XIV. In the early 19th century, the balance tipped, and few would have denied that technology had profoundly changed warfare. All this is a far cry, however, from any contemporary perception of a "Military Revolution" in the 16th and 17th centuries.

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The assumption that the most important aim of war is to create a better peace than existed before the war, i.e. a peace with justice, was self-evident for writers prior to Clausewitz. This does not mean that princes saw this as their priority, but theoreticians did. This changed dramatically with the Napoleonic Wars: Clausewitz initiated an era where writers on strategy paid no heed to what would come after military victory, now seen as the be-all and end-all of war. Terrible consequences flowed from this, and a series of ephemeral victories leading to new wars. It was only around the Second World War, to some in itself the consequence of this obsession with victory and not with peace, that it began to dawn on writers that peace, not military victory must be the ultimate aim to be kept in sight.

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Pulsed terahertz imaging is being developed as a technique to image obscured mural paintings. Due to significant advances in terahertz technology, portable systems are now capable of operating in unregulated environments and this has prompted their use on archaeological excavations. August 2011 saw the first use of pulsed terahertz imaging at the archaeological site of Çatalhöyük, Turkey, where mural paintings dating from the Neolithic period are continuously being uncovered by archaeologists. In these particular paintings the paint is applied onto an uneven surface, and then covered by an equally uneven surface. Traditional terahertz data analysis has proven unsuccessful at sub-surface imaging of these paintings due to the effect of these uneven surfaces. For the first time, an image processing technique is presented, based around Gaussian beam-mode coupling, which enables the visualization of the obscured painting.

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The steady growth of social and environmental reporting (SER) is being accompanied by an increase in social and environmental reporting assurance (SERA). The existing literature on SERA suggests that it is necessary to build credibility and trust among corporate stakeholders. Prior work has also found evidence of managerial and professional capture of SERA. In this paper, we present empirical evidence from interviews with corporate social responsibility representatives from 20 UK listed companies on whether they consider SERA to be necessary. We believe this to be the first research into SERA that uses an interview method. Our interviews revealed mixed feelings. Half of the respondents believed that external SERA would enhance credibility and trust which confirmed the prior literature. However, the other half believed that external SERA was not necessary, believing that internal assurance was sufficient. This was because they saw SERA as predominantly a managerial tool, useful for checking the efficiency of internal management control systems, rather than as a mechanism for enhancing corporate accountability to stakeholders and building credibility and trust. The potential for SERA to be a mechanism whereby greater dialogue is created between companies and their stakeholders on social and environmental issues is not being harnessed. This paper thus demonstrates a fundamental difference between the external prior normative literature and the managerial motivation in the SERA area.

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The article looks at three antifascist films from the 1980s by the East German film company DEFA: Jürgen Brauer's Pugowitza (1981), Egon Schlegel's Die Schüsse der Arche Noah (1983), and Helmut Dziuba's Jan auf der Zille (1986), which during this final decade of the East German state re-examine an ideologically seminal constellation of the GDR's official antifascism – the relationship between antifascist father and son. Linking generational and political succession, the father-son relationship helped to legitimise the GDR as a state in which the young continued the antifascist fight of the old communists against the Nazi dictatorship. From the 1950s on, DEFA films contributed to the visualisation of this relationship, codifying it not only as heroic but also as ‘natural’: the assumed innocence of the communist son was meant to naturalise the father's antifascist/communist cause. The 1980s saw this naturalised political succession questioned. By re-telling the canonised father-son story, the three films visualise the generational antifascist contract as flawed. Re-deploying the son's assumed innocence in a critique of the father, they explore new endings to the antifascist story and revive the discussion of categories like ‘victim’ and ‘perpetrator’.// Der Aufsatz untersucht drei antifaschistische Filme der ostdeutschen Filmgesellschaft DEFA aus den 1980er Jahren: Jürgen Brauers Pugowitza (1981), Egon Schlegels Die Schüsse der Arche Noah (1983) und Helmut Dziubas Jan auf der Zille (1986). Alle drei Filme wurden im letzten Jahrzehnt der DDR gedreht und greifen eine ideologisch tragende Konstellation des offiziellen DDR-Antifaschismus auf – die Beziehung zwischen antifaschistischem Vater und Sohn. In der Vater-Sohn-Beziehung verband sich Generationenabfolge mit politischer Nachkommenschaft, eine Verbindung, die half, die DDR als einen Staat zu legitimieren, in dem die Jungen den antifaschistischen Kampf der alten Kommunisten gegen die Nazi-Diktatur weiterführten. Seit den 1950er Jahren beteiligte sich die DEFA an der Visuali-sierung dieser Beziehung und kodifizierte sie nicht nur als heldenhaft, sondern auch als ‘natürlich’: die behauptete Unschuld der kommunistschen Söhne diente dazu, den antifaschistisch-kommunistischen Kampf der Väter zu naturalisieren. Die solcher Art politisch interpretierte Generationenabfolge verlor ihre Natürlichkeit, als sie in den 1980er Jahren kritisch befragt wurde. Im nochmaligen Erzählen der kanonisierten Vater-Sohn-Geschichte wird die Brüchigkeit des antifaschistischen Gesellschaftsvertrags in allen drei Filmen sichtbar. Die vermeintliche Unschuld der Söhne wird nun zu einer Kritik der Väter genutzt, wobei die Filme ein neues Ende für die antifaschistische Geschichte erkunden und die Debatte über Kategorien wie ‘Opfer’ und ‘Täter’ wieder aufnehmen.

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We present a highly accurate tool for the simulation of shear Alfven waves (SAW) in collisionless plasma. SAW are important in space plasma environments because for small perpendicular scale lengths they can support an electric field parallel to the ambient magnetic field. Electrons can be accelerated by the parallel electric field and these waves have been implicated as the source of vibrant auroral displays. However, the parallel electric field carried by SAW is small in comparison to the perpendicular electric field of the wave, making it difficult to measure directly in the laboratory, or by satellites in the near-Earth plasma environment. In this paper, we present a simulation code that provides a means to study in detail the SAW-particle interaction in both space and laboratory plasma. Using idealised, small-amplitude propagating waves with a single perpendicular wavenumber, the simulation code accurately reproduces the damping rates and parallel electric field amplitudes predicted by linear theory for varying temperatures and perpendicular scale lengths. We present a rigorous kinetic derivation of the parallel electric field strength for small-amplitude SAW and show that commonly-used inertial and kinetic approximations are valid except for where the ratio of thermal to Alfv\'{e}n speed is between 0.7 and 1.0. We also present nonlinear simulations of large-amplitude waves and show that in cases of strong damping, the damping rates and parallel electric field strength deviate from linear predictions when wave energies are greater than only a few percent of the plasma kinetic energy, a situation which is often observed in the magnetosphere. The drift-kinetic code provides reliable, testable predictions of the parallel electric field strength which can be investigated directly in the laboratory, and will help to bridge the gap between studies of SAW in man-made and naturally occuring plasma.