We use kinetic particle-in-cell and magnetohydrodynamic simulations supported by an observational dataset to investigate magnetic reconnection in clusters of null points in space plasma. The magnetic configuration under investigation is driven by fast adiabatic flux rope compression that dissipates almost half of the initial magnetic field energy. In this phase powerful currents are excited producing secondary instabilities, and the system is brought into a state of `intermittent turbulence' within a few ion gyro-periods. Reconnection events are distributed all over the simulation domain and energy dissipation is rather volume-filling. Numerous spiral null points interconnected via their spines form null lines embedded into magnetic flux ropes; null point pairs demonstrate the signatures of torsional spine reconnection. However, energy dissipation mainly happens in the shear layers formed by adjacent flux ropes with oppositely directed currents. In these regions radial null pairs are spontaneously emerging and vanishing, associated with electron streams and small-scale current sheets. The number of spiral nulls in the simulation outweighs the number of radial nulls by a factor of 5\---10, in accordance with Cluster observations in the Earth's magnetosheath. Twisted magnetic fields with embedded spiral null points might indicate the regions of major energy dissipation for future space missions such as Magnetospheric Multiscale Mission (MMS).
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gold |
citations | 32 | |
popularity | Top 10% | |
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doi: 10.2514/1.j053837
Ongoing research toward the reduction of environmental noise from aircraft is investigating the possible shielding of engine-noise sources by novel airframe configurations. To assess the noise-reduction benefits attainable from such configurations, it is necessary to develop appropriate acoustic evaluation tools. In this paper, a jet-noise-shielding-prediction methodology is described. The Tam–Auriault (“Jet Mixing Noise from Fine-Scale Turbulence,” AIAA Journal, Vol. 37, No. 2, 1999, pp. 145–153) jet-noise model with a Reynolds-averaged Navier–Stokes solution input, together with a Fresnel–Kirchhoff diffraction method (Fundamentals of Physical Acoustics, Wiley-Interscience, New York, 2000, pp. 472–494), is used to make isolated and shielded far-field jet-noise predictions. This methodology is employed as a sensitivity-analysis tool to establish the relative importance of the source location, spatial extent, and directivity in jet-noise-shielding predictions. Predictions have been made for a shielded sing...
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citations | 1 | |
popularity | Average | |
influence | Average | |
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Much of the academic and commercial work which seeks to innovate around technology has been dismissed as "solutionist" because it solves problems that don't exist or ignores the complexity of personal, political and environmental issues. This paper traces the "solutionism" critique to its origins in city planning and highlights the original concern with imaging and representation in the design process. It is increasingly cheap and easy to create compelling and seductive images of concept designs, which sell solutions and presume problems. We consider a range of strategies, which explicitly reject the search for "solutions". These include design fiction and critical design but also less well-known techniques, which aim for unuseless, questionable and silly designs. We present two examples of "magic machine" workshops where participants are encouraged to reject realistic premises for possible technological interventions and create absurd propositions from lo-fi materials. We argue that such practices may help researchers resist the impulse towards solutionism and suggest that attention to representation during the ideation process is a key strategy for this.
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bronze |
citations | 145 | |
popularity | Top 1% | |
influence | Top 10% | |
impulse | Top 1% |
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Anaphylaxis is a life-threatening allergic reaction which is rapid in onset. Adolescents living with anaphylaxis risk often lack the knowledge and skills required to safely manage their condition or talk to friends about it. We designed an educational intervention comprising group discussion around videos of simulated anaphylaxis scenarios and a mobile application containing video-based branching anaphylaxis narratives. We trialed the intervention with 36 nut allergic adolescents. At 1-year follow-up participants had improved adrenaline auto-injector skills and carriage, disease- and age-specific Quality of Life and confidence in anaphylaxis management. At 3-year follow-up adrenaline carriage improved further and confidence remained higher. Participants expressed how the education session was a turning point in taking control of their allergy and how the app facilitated sharing about anaphylaxis with others. We contribute insights regarding design of mobile self-care and peer-support applications for health in adolescence, and discuss strengths and limitations of video-based mobile health interventions.
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citations | 6 | |
popularity | Average | |
influence | Average | |
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doi: 10.1364/ome.9.004409
The use of 3D-printing for designing a simple wavelength tunable device based on fiber Bragg gratings is demonstrated. Using fused deposition modeling (FDM), the fiber Bragg grating is embedded into a beam of polyethylene terephthalate glycol (PETG). Through bending, resulting in compression or tension of the optical fiber, the Bragg wavelength could be continuously tuned over a range of 60 nm, with maintained reflectivity and 3-dB linewidth.
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gold |
citations | 7 | |
popularity | Top 10% | |
influence | Average | |
impulse | Top 10% |
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Reducing the use of energy is important for several reasons, such as saving money and reducing impact on the climate. However, the awareness among non-experts of how much energy is required by different activities is generally low, which can lead to wrong prioritizations. In this study, we have developed an interactive tool to increase “energy awareness”. A group of 58 students first did a test to benchmark their current energy awareness, then tried the tool for 10 min, and then did the same test immediately after trying the prototype and one week after trying the prototype. In addition, they answered questions regarding which, if any, of the energy requirement of different activities surprised them, any thoughts about their own energy use aroused after using the prototype and what they thought about using the tool compared to more conventional methods of learning. The results showed a significant learning effect in energy awareness with a very strong effect size of 1.689, that they were most surprised by the energy required to produce a hamburger, 39 of 58 explicitly said they intended to change one or more aspects in order to improve their energy use, where 24 actions involved changing habits and 18 actions was of a one-time investment character. The attitude towards using such a tool instead of more conventional learning was very good and the words most frequently used to describe the tool was good, simple and easy to use, fun, and interesting, but five users also said they were bored after a while. In total the results indicate that using an interactive tool like this even for a limited time is a good way to in an efficient and fun way increase energy awareness.
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citations | 6 | |
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influence | Average | |
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This paper provides a study of a workshop which invited composers, musicians, and sound designers to explore instruments from the history of electronic sound in Sweden. The workshop participants applied media archaeology methods towards analyzing one particular instrument from the past, the Dataton System 3000. They then applied design fiction methods towards imagining several speculative instruments of the future. Each stage of the workshop revealed very specific utopian ideas surrounding the design of sound instruments. After introducing the background and methods of the workshop, the authors present an overview and thematic analysis of the workshop's outcomes. The paper concludes with some reflections on the use of this method-in-progress for investigating the ethics and affordances of historical electronic sound instruments. It also suggests the significance of ethics and affordances for the design of contemporary instruments.
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citations | 0 | |
popularity | Average | |
influence | Average | |
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pmid: 28542191
pmc: PMC5464673
Brain activity displays a large repertoire of dynamics across the sleep-wake cycle and even during anesthesia. It was suggested that criticality could serve as a unifying principle underlying the diversity of dynamics. This view has been supported by the observation of spontaneous bursts of cortical activity with scale-invariant sizes and durations, known as neuronal avalanches, in recordings of mesoscopic cortical signals. However, the existence of neuronal avalanches in spiking activity has been equivocal with studies reporting both its presence and absence. Here, we show that signs of criticality in spiking activity can change between synchronized and desynchronized cortical states. We analyzed the spontaneous activity in the primary visual cortex of the anesthetized cat and the awake monkey, and found that neuronal avalanches and thermodynamic indicators of criticality strongly depend on collective synchrony among neurons, LFP fluctuations, and behavioral state. We found that synchronized states are associated to criticality, large dynamical repertoire and prolonged epochs of eye closure, while desynchronized states are associated to sub-criticality, reduced dynamical repertoire, and eyes open conditions. Our results show that criticality in cortical dynamics is not stationary, but fluctuates during anesthesia and between different vigilance states.
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gold |
citations | 86 | |
popularity | Top 1% | |
influence | Top 10% | |
impulse | Top 1% |
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doi: 10.1049/mia2.12028
Abstract A parallel‐plate waveguide half‐Luneburg geodesic lens is designed and experimentally validated in the Ka‐band. The geodesic lens profile is modulated using spline functions to reduce its height, while the symmetry halving the lens enables reduction of its in‐plane dimensions. This design provides high gain, equivalent to that of a full‐Luneburg lens, over a reduced angular range of ±20° to ±30° in azimuth. The specific design reported here has a maximum realized gain of 23.3 dBi in measurement, compared with 23.8 dBi for a full‐Luneburg lens twice the size of this design. Very wideband operation is demonstrated both in simulations and measurements. This design is of interest for applications having limited space like millimetre‐wave systems on board cubesats and small satellites.
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Published in a Diamond OA journal |
citations | 37 | |
popularity | Top 10% | |
influence | Top 10% | |
impulse | Top 10% |
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In this article, we discuss the role played by graffiti in representing, fomenting and studying binary and non-binary sentiments of ‘us’ and ‘them’. Through asocio-textual analysis of examples of p...
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citations | 1 | |
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influence | Average | |
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We use kinetic particle-in-cell and magnetohydrodynamic simulations supported by an observational dataset to investigate magnetic reconnection in clusters of null points in space plasma. The magnetic configuration under investigation is driven by fast adiabatic flux rope compression that dissipates almost half of the initial magnetic field energy. In this phase powerful currents are excited producing secondary instabilities, and the system is brought into a state of `intermittent turbulence' within a few ion gyro-periods. Reconnection events are distributed all over the simulation domain and energy dissipation is rather volume-filling. Numerous spiral null points interconnected via their spines form null lines embedded into magnetic flux ropes; null point pairs demonstrate the signatures of torsional spine reconnection. However, energy dissipation mainly happens in the shear layers formed by adjacent flux ropes with oppositely directed currents. In these regions radial null pairs are spontaneously emerging and vanishing, associated with electron streams and small-scale current sheets. The number of spiral nulls in the simulation outweighs the number of radial nulls by a factor of 5\---10, in accordance with Cluster observations in the Earth's magnetosheath. Twisted magnetic fields with embedded spiral null points might indicate the regions of major energy dissipation for future space missions such as Magnetospheric Multiscale Mission (MMS).
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gold |
citations | 32 | |
popularity | Top 10% | |
influence | Top 10% | |
impulse | Top 10% |
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