Electrodynamics and energy characteristics of aurora at high resolution by optical methods

Technological advances leading to improved sensitivity of optical detectors have revealed that aurora contains a richness of dynamic and thin filamentary structures, but the source of the structured emissions is not fully understood. In addition, high resolution radar data have indicated that thin auroral arcs can be correlated with highly varying and large electric fields, but the detailed picture of the electrodynamics of auroral filaments is yet incomplete. The ASK instrument is a state-of-the-art ground-based instrument designed to investigate these smallest auroral features at very high spatial and temporal resolution, by using three EMCCDs in parallel for three different narrow spectral regions. ASK is specifically designed to utilize a new optical techique to determine the ionospheric electric fields. By imaging the long-lived O+ line at 732~nm, the plasma flow in the region can be traced, and since the plasma motion is controlled by the electric field, the field strength and direction can be estimated at unprecedented resolution. The method is a powerful tool to investigate the detailed electrodynamics and current systems around the thin auroral filaments. The two other ASK cameras provide information on the precipitation by imaging prompt emissions, and the emission brightness ratio of the two emissions, together with ion chemistry modeling, is used to give information on the energy and energy flux of the precipitating electrons. In this paper, we discuss these measuring techniques, and give a few examples of how they are used to reveal the nature and source of fine scale structuring in the auror

Reconstruction of Fine Scale Auroral Dynamics

We present a feasibility study for a high frame rate, short baseline auroral tomographic imaging system useful for estimating parametric variations in the precipitating electron number flux spectrum of dynamic auroral events. Of particular interest are auroral substorms, characterized by spatial variations of order 100 m and temporal variations of order 10 ms. These scales are thought to be produced by dispersive Alfvén waves in the near-Earth magnetosphere. The auroral tomography system characterized in this paper reconstructs the auroral volume emission rate to estimate the characteristic energy and location in the direction perpendicular to the geomagnetic field of peak electron precipitation flux using a distributed network of precisely synchronized ground-based cameras. As the observing baseline decreases, the tomographic inverse problem becomes highly ill-conditioned; as the sampling rate increases, the signal-to-noise ratio degrades and synchronization requirements become increasingly critical. Our approach to these challenges uses a physics-based auroral model to regularize the poorly-observed vertical dimension. Specifically, the vertical dimension is expanded in a low-dimensional basis consisting of eigenprofiles computed over the range of expected energies in the precipitating electron flux, while the horizontal dimension retains a standard orthogonal pixel basis. Simulation results show typical characteristic energy estimation error less than 30% for a 3 km baseline achievable within the confines of the Poker Flat Research Range, using GPS-synchronized Electron Multiplying CCD cameras with broad-band BG3 optical filters that pass prompt auroral emissions.National Science Foundation Atmosphere and Geospace Directorate, Grants 1216530, 123737

A pilot study on spatial hearing in children with congenital unilateral aural atresia

Despite normal hearing in one ear, individuals with congenital unilateral aural atresia may perceive difficulties in everyday listening conditions typically containing multiple sound sources. While previous work shows that intervention with bone conduction devices may aid spatial hearing for some children, testing conditions are often arranged to maximize any benefit and are not very similar to daily life. The benefit from amplification on spatial tasks has been found to vary between individuals, for reasons not entirely clear. This study has sought to expand on the limited knowledge on how children with unilateral aural atresia recognize speech masked by competing speech, and how horizontal sound localization accuracy is affected by the degree of unilateral hearing loss and by amplification using unilateral bone conduction devices when fitted before 3 years of age. In a within-subject, repeated measures design, including 11 children (mean age = 7.9 years), bone conduction hearing device (BCD) amplification did not negatively affect horizontal sound localization accuracy. The effect on speech recognition scores showed greater inter-individual variability. No benefit from amplification on a group level was found. There was no association between age at fitting and the benefit of the BCD. For children with poor unaided sound localization accuracy, there was a greater BCD benefit. Unaided localization accuracy increased as a function of decreasing hearing thresholds in the atretic ear. While it is possible that low sound levels in the atretic ear provided access to interaural localization cues for the children with the lowest hearing thresholds, the association has to be further investigated in a larger sample of children

High-speed stereoscopy of aurora

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月）　国立極地研究所 2階 大会議

Compound auroral micromorphology: ground-based high-speed imaging

Auroral microphysics still remains partly unexplored. Cutting-edge ground-based optical observations using scientific complementary metal-oxide semiconductor (sCMOS) cameras recently enabled us to observe the fine-scale morphology of bright aurora at magnetic zenith for a variety of rapidly varying features for long uninterrupted periods. We report two interesting examples of combinations of fine-scale rapidly varying auroral features as observed by the sCMOS cameras installed at Poker Flat Research Range (PFRR), Alaska, in February 2014. The first example shows that flickering rays and pulsating modulation simultaneously appeared at the middle of a surge in the pre-midnight sector. The second example shows localized flickering aurora associated with growing eddies at the poleward edge of an arc in the midnight secto

Herbivore Effects on Ecosystem Process Rates in a Low-Productive System

Mammalian herbivores shape the structure and function of many nutrient-limited or low-productive terrestrial ecosystems through modification of plant communities and plant–soil feedbacks. In the tundra biome, mammalian herbivores may both accelerate and decelerate plant biomass growth, microbial activity and nutrient cycling, that is, ecosystem process rates. Selective foraging and associated declines of palatable species are known to be major drivers of plant–soil feedbacks. However, declines in dominant plants of low palatability often linked with high herbivore densities may also modify ecosystem process rates, yet have received little attention. We present data from an island experiment with a 10-year vole density manipulation, to test the hypothesis that herbivores accelerate process rates by decreasing the relative abundance of poorly palatable plants to palatable ones. We measured plant species abundances and community composition, nitrogen contents of green plant tissues and multiple soil and litter variables under high and low vole density. Corroborating our hypothesis, periodic high vole density increased ecosystem process rates in low-productive tundra. High vole density was associated with both increasing relative abundance of palatable forbs over unpalatable evergreen dwarf shrubs and higher plant N content both at species and at community level. Changes in plant community composition, in turn, explained variation in microbial activity in litter and soil inorganic nutrient availability. We propose a new conceptual model with two distinct vole–plant–soil feedback pathways. Voles may drive local plant–soil feedbacks that either increase or decrease ecosystem process rates, in turn promoting heterogeneity in vegetation and soils across tundra landscapes.</p

Cannabisanvändande ungdomar : En kvalitativ intervjustudie med socialarbetare

Syftet med denna studie har varit att erhålla en djupare kunskap om ungdomars användning av cannabis. För att göra detta utgår denna studie från en kvalitativ intervjumetod där vi har intervjuat fyra socialarbetare samt en polisman. Samtliga informanter har erfarenhet av arbete med ungdomar som brukat cannabis. För att analysera resultaten som uppkommit under intervjuer har vi valt att använda oss av de teoretiska perspektiven social konstruktionism samt utvecklingspsykopatologi. Vidare har vi i studien använt risk och skyddsfaktorer för att analysera vilka faktorer som kan påverka att en ungdom använder sig av cannabis. Resultaten pekar på att bakomliggande faktorer vid bruket är psykisk ohälsa, neuropsykiatrisk diagnos såsom ADHD eller ADD och en problematisk hemmiljö. I resultatet diskuteras vidare om riskfaktorer såsom en bristande skolgång samt huruvida könet har någon betydelse eller skillnad bland de som använder sig av cannabis som berusningsmedel. Ett av de viktigaste resultaten som framkommer är att psykisk ohälsa är den vanligaste gemensamma riskfaktorn hos de ungdomar som använder sig av cannabis och som blir aktuella på socialtjänsten. Nyckelord: cannabis, socialarbetare, social kontruktionism, socialtjänst, ungdomar The aim of this study was to obtain a deeper understanding of young people's use of cannabis. To do that is this study made out of a qualitative interview method where we have interviewed four social workers and one policeman. All informants have experience of working with young people who used cannabis. To analyse the findings raised during the interviews, we have chosen to use the theoretical perspectives of social constructionism and the development of psychopathology. Furthermore, we have in the study used the risk and protective factors to analyse the factors that can influence a young person use of cannabis. The result indicates that the factors behind the use of cannabis are mental illness, neuropsychiatric diagnosis as ADHD or ADD and a problematic home. This result further discussion of risk factors such as a lack of schooling and whether sex has any significance or difference among those who use cannabis as an intoxicant. One of the main results that emerge is that mental illness is the most common risk factor for young people who use cannabis, and who is current to the social services. Keywords: cannabis, social constructionism, social service, social worker, young people

Cannabisanvändande ungdomar : En kvalitativ intervjustudie med socialarbetare

Syftet med denna studie har varit att erhålla en djupare kunskap om ungdomars användning av cannabis. För att göra detta utgår denna studie från en kvalitativ intervjumetod där vi har intervjuat fyra socialarbetare samt en polisman. Samtliga informanter har erfarenhet av arbete med ungdomar som brukat cannabis. För att analysera resultaten som uppkommit under intervjuer har vi valt att använda oss av de teoretiska perspektiven social konstruktionism samt utvecklingspsykopatologi. Vidare har vi i studien använt risk och skyddsfaktorer för att analysera vilka faktorer som kan påverka att en ungdom använder sig av cannabis. Resultaten pekar på att bakomliggande faktorer vid bruket är psykisk ohälsa, neuropsykiatrisk diagnos såsom ADHD eller ADD och en problematisk hemmiljö. I resultatet diskuteras vidare om riskfaktorer såsom en bristande skolgång samt huruvida könet har någon betydelse eller skillnad bland de som använder sig av cannabis som berusningsmedel. Ett av de viktigaste resultaten som framkommer är att psykisk ohälsa är den vanligaste gemensamma riskfaktorn hos de ungdomar som använder sig av cannabis och som blir aktuella på socialtjänsten. Nyckelord: cannabis, socialarbetare, social kontruktionism, socialtjänst, ungdomar The aim of this study was to obtain a deeper understanding of young people's use of cannabis. To do that is this study made out of a qualitative interview method where we have interviewed four social workers and one policeman. All informants have experience of working with young people who used cannabis. To analyse the findings raised during the interviews, we have chosen to use the theoretical perspectives of social constructionism and the development of psychopathology. Furthermore, we have in the study used the risk and protective factors to analyse the factors that can influence a young person use of cannabis. The result indicates that the factors behind the use of cannabis are mental illness, neuropsychiatric diagnosis as ADHD or ADD and a problematic home. This result further discussion of risk factors such as a lack of schooling and whether sex has any significance or difference among those who use cannabis as an intoxicant. One of the main results that emerge is that mental illness is the most common risk factor for young people who use cannabis, and who is current to the social services. Keywords: cannabis, social constructionism, social service, social worker, young people