3,301 research outputs found

    Orientation cues for high-flying nocturnal insect migrants: do turbulence-induced temperature and velocity fluctuations indicate the mean wind flow?

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    Migratory insects flying at high altitude at night often show a degree of common alignment, sometimes with quite small angular dispersions around the mean. The observed orientation directions are often close to the downwind direction and this would seemingly be adaptive in that large insects could add their self-propelled speed to the wind speed, thus maximising their displacement in a given time. There are increasing indications that high-altitude orientation may be maintained by some intrinsic property of the wind rather than by visual perception of relative ground movement. Therefore, we first examined whether migrating insects could deduce the mean wind direction from the turbulent fluctuations in temperature. Within the atmospheric boundary-layer, temperature records show characteristic ramp-cliff structures, and insects flying downwind would move through these ramps whilst those flying crosswind would not. However, analysis of vertical-looking radar data on the common orientations of nocturnally migrating insects in the UK produced no evidence that the migrants actually use temperature ramps as orientation cues. This suggests that insects rely on turbulent velocity and acceleration cues, and refocuses attention on how these can be detected, especially as small-scale turbulence is usually held to be directionally invariant (isotropic). In the second part of the paper we present a theoretical analysis and simulations showing that velocity fluctuations and accelerations felt by an insect are predicted to be anisotropic even when the small-scale turbulence (measured at a fixed point or along the trajectory of a fluid-particle) is isotropic. Our results thus provide further evidence that insects do indeed use turbulent velocity and acceleration cues as indicators of the mean wind direction

    Towards modelling X-ray reverberation in AGN: Piecing together the extended corona

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    Models of X-ray reverberation from extended coronae are developed from general relativistic ray tracing simulations. Reverberation lags between correlated variability in the directly observed continuum emission and that reflected from the accretion disc arise due to the additional light travel time between the corona and reflecting disc. X-ray reverberation is detected from an increasing sample of Seyfert galaxies and a number of common properties are observed, including a transition from the characteristic reverberation signature at high frequencies to a hard lag within the continuum component at low frequencies, as well a pronounced dip in the reverberation lag at 3keV. These features are not trivially explained by the reverberation of X-rays originating from simple point sources. We therefore model reverberation from coronae extended both over the surface of the disc and vertically. Causal propagation through its extent for both the simple case of constant velocity propagation and propagation linked to the viscous timescale in the underlying accretion disc is included as well as stochastic variability arising due to turbulence locally on the disc. We find that the observed features of X-ray reverberation in Seyfert galaxies can be explained if the long timescale variability is dominated by the viscous propagation of fluctuations through the corona. The corona extends radially at low height over the surface of the disc but with a bright central region in which fluctuations propagate up the black hole rotation axis driven by more rapid variability arising from the innermost regions of the accretion flow

    The Outsourcing Unit Working Research Paper Series Paper 14/1 – Cloud Services: The Great Equalizer for

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    Acknowledgements: We thank and acknowledge our research sponsor, Accenture. In particular, we are grateful to Miguel Gabriel Custodio, IT Strategy Australia/Cloud Strategy- APAC, for his support. We also thank the International Association of Outsourcing Professionals for their support in administering a survey, and Ken Saloway and Frank Casale for connecting us with SME cloud adopters

    Measuring the evolution of contemporary western popular music

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    Popular music is a key cultural expression that has captured listeners' attention for ages. Many of the structural regularities underlying musical discourse are yet to be discovered and, accordingly, their historical evolution remains formally unknown. Here we unveil a number of patterns and metrics characterizing the generic usage of primary musical facets such as pitch, timbre, and loudness in contemporary western popular music. Many of these patterns and metrics have been consistently stable for a period of more than fifty years, thus pointing towards a great degree of conventionalism. Nonetheless, we prove important changes or trends related to the restriction of pitch transitions, the homogenization of the timbral palette, and the growing loudness levels. This suggests that our perception of the new would be rooted on these changing characteristics. Hence, an old tune could perfectly sound novel and fashionable, provided that it consisted of common harmonic progressions, changed the instrumentation, and increased the average loudness.Comment: Supplementary materials not included. Please see the journal reference or contact the author

    Magnetic metamaterial superlens for increased range wireless power transfer.

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    The ability to wirelessly power electrical devices is becoming of greater urgency as a component of energy conservation and sustainability efforts. Due to health and safety concerns, most wireless power transfer (WPT) schemes utilize very low frequency, quasi-static, magnetic fields; power transfer occurs via magneto-inductive (MI) coupling between conducting loops serving as transmitter and receiver. At the "long range" regime - referring to distances larger than the diameter of the largest loop - WPT efficiency in free space falls off as (1/d)(6); power loss quickly approaches 100% and limits practical implementations of WPT to relatively tight distances between power source and device. A "superlens", however, can concentrate the magnetic near fields of a source. Here, we demonstrate the impact of a magnetic metamaterial (MM) superlens on long-range near-field WPT, quantitatively confirming in simulation and measurement at 13-16 MHz the conditions under which the superlens can enhance power transfer efficiency compared to the lens-less free-space system

    Schedule of Events

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    Theme: Remaking, Reshaping, and Restructuring A Celebration of Rev. Dr. Martin Luther King Jr. Chapel: Remaking, Reshaping, Restructuring our World, Rev. Dr. Barbara Reynolds Rev. Dr. Reynolds is an author, church pastor, and journalist who knew both Martin and Coretta King. Reynolds\u27 book, No, I Won’t Shut Up: 30 Years of Telling It Like It Is, includes a forward written by Coretta Scott King. Her latest book is co-written with Coretta Scott King, My Life, My Love, My Legacy (2017), a memoir focusing on King. Reynolds attended Howard University Divinity School in 1988, graduating in 1992 and was ordained as a minister in 1993, later earning a D. Min. from United Theological Seminary in Dayton, Ohio, in 1997. She also was the founder of Harriet’s Children, an organization that assisted women who struggle with alcohol and drug addiction. Workshops: Celebrating the Unity and Diversity of the Human Race through the Use of Forensics/Science, Dr. Dan King Martin Luther King, Jr. in Historical Context, Dr. Ben Wetzel Understanding Environmental Racism: The Disproportionate Burden of Pollution on Minorities in the U.S., Dr. Phil Grabowski The Last Lynching in Indiana: Racism and the Continuing Problem of Evil, Dr. Ed Meadors Play Performance Defamation (2012) - Todd Logan Defamation is an old-fashioned courtroom drama. The premise is a civil suit: Ms. Wade, an African-American business owner, is suing Mr. Golden, a Jewish real estate developer, for defamation. What follows is a 75-minute riveting trial that holds our prejudices and assumptions under a powerful lens, and does not let go except by way of an unsettling self-examination

    Creativity and Autonomy in Swarm Intelligence Systems

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    This work introduces two swarm intelligence algorithms -- one mimicking the behaviour of one species of ants (\emph{Leptothorax acervorum}) foraging (a `Stochastic Diffusion Search', SDS) and the other algorithm mimicking the behaviour of birds flocking (a `Particle Swarm Optimiser', PSO) -- and outlines a novel integration strategy exploiting the local search properties of the PSO with global SDS behaviour. The resulting hybrid algorithm is used to sketch novel drawings of an input image, exploliting an artistic tension between the local behaviour of the `birds flocking' - as they seek to follow the input sketch - and the global behaviour of the `ants foraging' - as they seek to encourage the flock to explore novel regions of the canvas. The paper concludes by exploring the putative `creativity' of this hybrid swarm system in the philosophical light of the `rhizome' and Deleuze's well known `Orchid and Wasp' metaphor

    High-Throughput Nanoliter Dispensing Device for Biological Applications

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    Pathogen identification is a field that can contribute largely to the prevention of the spreading of illness and disease. In the past, pathogen identification has been a long and arduous process due to the time-consuming processes and steps that requires technician’s time and effort. With new technologies emerging however, screening of bacteria colonies can be done in a quick and high-throughput way. The problem is that using the current methods, bacteria cannot be transferred to petri dishes fast enough to keep up with the new screening methods. The current study focuses on exploring different methods to create an ergonomic device that can dispense and inoculate bacteria cells onto petri dishes in a fast, repeatable, and high-throughput manner. The testing of bacteria in liquid allows for the most versatility because bacteria already suspended in liquid could be tested or bacteria could be suspended in liquid from a solid if needed. Different methods of dispensing liquid were tested such as solenoid valves, and different methods of dispenser movements in the X-Y plane around the surface of the petri dishes were tested such as a five-bar mechanism controlled by two rotary motors. It was found that a small solenoid valve in combination with either a five-bar mechanism with two motors or a simple XY stage were both ergonomic and able to provide high-throughput dispensing of bacteria colonies. Based on the devices performance, it can dispense 86 microliter droplets with 8 millimeters of spacing in 69 seconds (1.25 drops per second)

    Post-Covid Youth Work and Mental Wellbeing of Young People Across Scotland and England

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    This article seeks to contribute to the debate about the current and future support needs of young people (aged 11-25) across Scotland and England who are experiencing mental distress in the aftermath of the Covid-19 pandemic. In doing so, it focuses on the profession that works specifically with this age range – youth work - and youth work practice across Scotland and England, and then examines the challenges and opportunities for the profession. It concludes that youth work, and youth workers, are well placed to provide much needed initial mental health support to young people, but that the profession urgently needs the UK and Scottish Governments to financially (re)invest in its infrastructure to deliver this provision
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