1,120 research outputs found

    Holographic Dual of the Lowest Landau Level

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    We describe the lowest Landau level of a quantum electron star in AdS4. In the presence of a suitably strong magnetic field, the dynamics of fermions in the bulk is effectively reduced from four to two dimensions. These two-dimensional fermions can subsequently be treated using the techniques of bosonization and the difficult many-body problem of building a gravitating, charged quantum star is reduced to solving the sine-Gordon model coupled to a gauge field and a metric. The kinks of the sine-Gordon model provide the holographic dual of the lowest Landau levels of the strongly-coupled d=2+1 dimensional boundary field theory. The system exhibits order one oscillations in the magnetic susceptibility, now arising as a classical effect in the bulk. Moreover, as the chemical potential is varied, we find jumps in the charge density, oscillations in the fractionalised charge density and plateaux in the cohesive charge densityComment: 39 pages; 8 Figure

    NASA/USRA high altitude research aircraft. Gryphon: Soar like an eagle with the roar of a lion

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    At the equator, the ozone layer ranges from 65,000 to 130,000+ feet. This is beyond the capabilities of the ER-2, which is NASA's current high altitude reconnaissance aircraft. The Universities Space Research Association, in cooperation with NASA, is sponsoring an undergraduate program which is geared to designing an aircraft that can study the ozoned layer at the equator. This aircraft must be able to satisfy four mission profiles. Mission one is a polar mission which ranges from Chile to the South Pole and back to Chile, a total range of 6000 n. mi. at 100,000 feet with a 2500 lb. payload. The second mission is also a polar mission with a decreased altitude of 70,000 feet and an increased payload of 4000 lb. For the third mission, the aircraft will take-off at NASA Ames, cruise at 100,000 feet carrying a 2500 lb. payload, and land in Puerto Montt, Chile. The final mission requires the aircraft to take-off at NASA Ames, cruise at 100,000 feet with a 1000 lb. payload, make an excursion to 120,000 feet, and land at Howard AFB, Panama. All three missions require that a subsonic Mach number be maintained due to constraints imposed by the air sampling equipment. The aircraft need not be manned for all four missions. Three aircraft configurations were determined to be the most suitable for meeting the above requirements. The performance of each configuration is analyzed to investigate the feasibility of the project requirements. In the event that a requirement can not be obtained within the given constraints, recommendations for proposal modifications are given

    Portraits of resilience: headteachers in two different cultures

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    This article provides two ‘portraits’ of headteachers in primary schools in England and Hong Kong, derived from semi-structured interviews with these individuals. Contrary to some claims that such a small sample is worthless, this article argues that what is most meaningful is sometimes derived from the singular and unique; that generalisations in education are as likely to be useful if they are ‘fuzzy’ generalisations as if they are from scientific or statistical generalisations; and that the individual case can strip away the clutter of large contexts and allow recognition of a common shared humanity. What these portraits also show is that responses to larger contexts are heavily dependent on personality and local context, and that if policy implementation and professional development are to have impact, then an attention to the personal and the local are going to be critical factors in any success in these areas

    Zone management in precision agriculture by matching fertiliser input to crop demand

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    Growers in Western Australia who have been yield mapping since the mid 1990s have come to realise that grain yield varies across different zones of their paddocks in any given year, as well as between years depending on the seasonal conditions and crop type. This within paddock variation can be as much as tenfold. Higher yielding areas can be due to better growing conditions (which increases the demand for nutrients) and/or better nutrient supply (which reduces the need for some fertiliser inputs). Hence, it is essential to determine the cause of the variation before optimum fertilising strategies can be developed.https://researchlibrary.agric.wa.gov.au/bulletins/1190/thumbnail.jp

    Values, priorities and responses: Comparing English headteachers' and Hong Kong principals' perceptions of their work

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    This article investigates the perceptions of English headteachers and Hong Kong principals on the kinds of pressures that they believed affected the way they did their job, and in particular the degree to which they felt their governments were affecting their leadership role. The research utilised semi-structured interviews to generate written ‘portraits’ of these individuals, which were then examined to answer questions about current pressures. The findings suggested that (1) there was considerable variation in the manner these individuals responded to key issues; (2) all individuals prioritised local concerns, and particularly with consideration to the children in their care; (3) there was a greater sense of embattlement from the English headteachers and a more critical approach to legislation, than from the Hong Kong principals, though with considerable individual variation in the degree of overt resistance shown; (4) whilst current educational reforms in Hong Kong seemed to favour the development of creativity more than those in England, there was within both national contexts evidence of the damaging effects of the pace and quantity of reforms

    Modifying monolayer behaviour by incorporating subphase additives and improving Langmuir–Blodgett thin film deposition on optical fibres

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    Experiments showing the possibility of modifying the behaviour of calix[4]resorcinarene monolayers at the air–water interface and optimising the deposition of multilayer coatings onto optical fibres are presented. The nature of the subphase is fundamental to the behaviour of monolayers and their utility in coating and sensing applications. Here we show initial studies exploring the modification of the calix[4]resorcinarene monolayer–water interaction through the introduction of dipole altering alcohol additives to the aqueous subphase. We explored the effect of this modification for three small alcohols. The resulting isotherms of the materials showed a reduction in the surface pressure and area per molecule required in order for the monolayer to reach its point of collapse. Incorporation of alcohols shifted the point of collapse, leading to the application of ethanol being successful in improving the transfer of material via Langmuir–Blodgett coating onto optical fibres at lower pressures. This method may prove useful in allowing greater control over future sensor surface coatings

    Increasing Skin Infections and Staphylococcus aureus Complications in Children, England, 1997-2006

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    During 1997-2006, general practitioner consultations for skin conditions for children <18 years of age in England increased 19%, from 128.5 to 152.9/1,000 child-years, and antistaphylococcal drug prescription rates increased 64%, from 17.8 to 29.1/1,000 child-years. During the same time period, hospital admissions for Staphylococcus aureus infections rose 49% from 53.4 to 79.3/100,000 child-years.link_to_subscribed_fulltex

    MadEye: Boosting Live Video Analytics Accuracy with Adaptive Camera Configurations

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    Camera orientations (i.e., rotation and zoom) govern the content that a camera captures in a given scene, which in turn heavily influences the accuracy of live video analytics pipelines. However, existing analytics approaches leave this crucial adaptation knob untouched, instead opting to only alter the way that captured images from fixed orientations are encoded, streamed, and analyzed. We present MadEye, a camera-server system that automatically and continually adapts orientations to maximize accuracy for the workload and resource constraints at hand. To realize this using commodity pan-tilt-zoom (PTZ) cameras, MadEye embeds (1) a search algorithm that rapidly explores the massive space of orientations to identify a fruitful subset at each time, and (2) a novel knowledge distillation strategy to efficiently (with only camera resources) select the ones that maximize workload accuracy. Experiments on diverse workloads show that MadEye boosts accuracy by 2.9-25.7% for the same resource usage, or achieves the same accuracy with 2-3.7x lower resource costs.Comment: 19 pages, 16 figure
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