Dissecting bombs and bursts: non-LTE inversions of low-atmosphere reconnection in SST and IRIS observations

Ellerman bombs and UV bursts are transient brightenings that are ubiquitously observed in the lower atmospheres of active and emerging flux regions. Here we present inversion results of SST/CRISP and CHROMIS, as well as IRIS data of such transient events. Combining information from the Mg II h & k, Si IV and Ca II 8542A and Ca II H & K lines, we aim to characterise their temperature and velocity stratification, as well as their magnetic field configuration. We find average temperature enhancements of a few thousand kelvin close to the classical temperature minimum, but localised peak temperatures of up to 10,000-15,000 K from Ca II inversions. Including Mg II generally dampens these temperature enhancements to below 8000 K, while Si IV requires temperatures in excess of 10,000 K at low heights, but may also be reproduced with secondary temperature enhancements of 35,000-60,000 K higher up. However, reproducing Si IV comes at the expense of overestimating the Mg II emission. The line-of-sight velocity maps show clear bi-directional jet signatures and strong correlation with substructure in the intensity images, with slightly larger velocities towards the observer than away. The magnetic field parameters show an enhancement of the horizontal field co-located with the brightenings at similar heights as the temperature increase. We are thus able to largely reproduce the observational properties of Ellerman bombs with UV burst signature with temperature stratifications peaking close to the classical temperature minimum. Correctly modelling the Si IV emission in agreement with all other diagnostics is, however, an outstanding issue. Accounting for resolution differences, fitting localised temperature enhancements and/or performing spatially-coupled inversions is likely necessary to obtain better agreement between all considered diagnostics.Comment: Accepted for publication in Astronomy & Astrophysics. 24 pages, 17 figure

Health-related costs in a sample of premenopausal non-diabetic overweight or obese females in Antwerp region : a cost-of-illness analysis

Background: People with overweight or obesity are at increased risk for disease later in life which cause important health costs. The aim of this study was to estimate the health status and the corresponding costs in a sample of females with overweight or obesity which were participating in a Randomized Controlled Trial (RCT) exploring the effect of lifestyle habits changes on ectopic adipose tissue. Methods: Sixty-two non-diabetic premenopausal females without major comorbidities of overweight and obesity were recruited among patients visiting endocrinologists at the obesity clinic of the University Hospital of Antwerp and the University of Antwerp. A RCT-embedded cost-of-illness approach with societal perspective, based on self-reported questionnaires and cost diaries (3 months recall) was applied to estimate the prevalence of different comorbidities and the related direct and indirect costs in this sample of overweight or obese females. The European Quality-of-Life-5D questionnaire was used to define the health state and the corresponding utility index of the participants. Results: The average direct health costs and health utilities observed in this sample were comparable with the general Flemish female population. This may partially be explained by the strict inclusion criteria of the RCT (i.e. overweight or obesity without diabetes type 2 or cardiovascular diseases). However, 15% of the participants had five or more comorbidities resulting in higher average costs and lower average health utility as compared to the general population, only 3 participants were diagnozed with the metabolic syndrome. In this subsample productivity was low due to high average absenteeism, yielding important total costs for the society. Conclusion: Secondary prevention to avoid health deterioration in overweight or obese females without major comorbidies is needed to contain health care costs. Trial registration: ClinicalTrials.gov: NCT02831621, approval of the ethics committee of the University Hospital of Antwerp (number: 14/17/205 -ref: 7543075363)

Intermittent reconnection and plasmoids in UV bursts in the low solar atmosphere

Magnetic reconnection is thought to drive a wide variety of dynamic phenomena in the solar atmosphere. Yet the detailed physical mechanisms driving reconnection are difficult to discern in the remote sensing observations that are used to study the solar atmosphere. In this paper we exploit the high-resolution instruments Interface Region Imaging Spectrograph (IRIS) and the new CHROMIS Fabry-Perot instrument at the Swedish 1-m Solar Telescope (SST) to identify the intermittency of magnetic reconnection and its association with the formation of plasmoids in so-called UV bursts in the low solar atmosphere. The Si IV 1403A UV burst spectra from the transition region show evidence of highly broadened line profiles with often non-Gaussian and triangular shapes, in addition to signatures of bidirectional flows. Such profiles had previously been linked, in idealized numerical simulations, to magnetic reconnection driven by the plasmoid instability. Simultaneous CHROMIS images in the chromospheric Ca II K 3934A line now provide compelling evidence for the presence of plasmoids, by revealing highly dynamic and rapidly moving brightenings that are smaller than 0.2 arcsec and that evolve on timescales of order seconds. Our interpretation of the observations is supported by detailed comparisons with synthetic observables from advanced numerical simulations of magnetic reconnection and associated plasmoids in the chromosphere. Our results highlight how subarcsecond imaging spectroscopy sensitive to a wide range of temperatures combined with advanced numerical simulations that are realistic enough to compare with observations can directly reveal the small-scale physical processes that drive the wide range of phenomena in the solar atmosphere.Comment: Accepted for publication in Astrophysical Journal Letters. Movies are available at http://folk.uio.no/rouppe/plasmoids_chromis

Factors Affecting The Efficiency Of Fox (Vulpes Vulpes) Baiting Practices On The Central Tablelands Of New South Wales

The European red fox (Vulpes vulpes L.) is a well known predator of native species and domestic stock, and is recognised as one of Australia’s most devastating vertebrate pests. Current fox management relies heavily on poisoning using baits impregnated with sodium monofluoroacetate (1080). This reliance on 1080 is likely to continue given the lack of viable alternatives for controlling foxes, so that, in the meanwhile, it is important to improve the efficiency of the current techniques. Factors affecting the susceptibility of individual foxes to bait include their ability to locate it, as well as the bait’s palatability and toxicity. The economic costs associated with using different bait types, the pattern and density of their distribution will also affect the efficiency of control programs. It is essential to examine and refine all such issues to ensure efficient use of the 1080 baiting technique. This thesis focuses generally on problems associated with management of the fox in eastern Australia. More specifically, I investigate the factors affecting the efficiency of fox baiting practices on the central tablelands of New South Wales. The study was conducted largely on agricultural lands near the town of Molong (33010’ 37”S, 148087’15”E) on the central tablelands of New South Wales. This area was chosen as it is broadly representative, in terms of land use, of a large region of eastern Australia. The highly modified, predominantly agricultural landscapes near Molong are well suited to foxes, and conflict with the predominantly pastoral community means that fox management is widely undertaken. I determined the persistence of 1080 in two commonly used bait types, Foxoff® and chicken wingettes, under different climatic and rainfall conditions. The rate of 1080 degradation did not change significantly between the central tablelands and the relatively hotter and drier western slopes. Foxoff® baits remained lethal for longer than wingettes under all conditions, although their rate of degradation generally increased with increasing rainfall. I confirmed the presence of defluorinating micro-organisms in thesoils of eastern Australia for the first time, and suggest that, following removal from the bait, 1080 would not persist in the environment for long. Bait should be attractive and highly palatable to ensure that the target species will find and consume it upon discovery. Caching, where discovered food is removed but not immediately consumed, may potentially reduce the efficacy and cost-effectiveness of baiting campaigns. I quantified the caching of chicken wingette, day-old chick and Foxoff® baits by inserting transmitters into bait material and assessing whether it was eaten or cached following removal. The intensity of caching did not change significantly between seasons. Type of bait had the largest influence on caching intensity, with a greater percentage of non-toxic Foxoff® baits (66.9%) being cached than either wingettes (5.7%) or day-old chicks (4.5%). The percentage of toxic (1080) baits cached was even greater, suggesting that 1080 bait may be less palatable, and detectable to foxes. I also investigated the use of conditioned taste aversion to reduce multiple bait uptake by foxes. Levamisole, an illness-inducing chemical, was added to bait and the fate of removed bait was again monitored via radio-telemetry. Following consumption of a levamisole-treated bait, foxes avoided eating treated baits but consumed untreated baits. I concluded that a reduction in bait consumption was achieved through learned aversion to levamisole rather than via conditioned taste aversion to baits. Adding levamisole to baits, especially non-toxic bait such as rabies vaccines, could potentially be used to reduce bait monopolisation by individual foxes. Fox density and den site preferences were assessed by investigating the distribution and density of fox natal dens on one property (9.6 km2) over three consecutive years. A total of 9 natal dens were located in 2000 and 2001, declining to 6 in 2002. No preference was shown for den sites on the basis of habitat, slope or aspect, but more dens were located under, or adjacent to cover. Assuming that each natal den represents a breeding pair and that the population sex ratio did not differ from parity (1:1), the site contained a prebreeding density of 1.9 foxes/km2 in 2000 and 2001, and 1.25 foxes/km2 in 2002. Given that the mean number of cubs is 4.0, the post-breeding density was estimated at 5.6 and 3.75 foxes/km2 in 2000/2001 and 2002, respectively. The results demonstrated that high densities of foxes occur on agricultural lands. The success and likely accuracy of the technique to monitor fox density suggests that it may be used to calibrate more efficient abundance estimates that will be essential for the strategic management of foxes in future. Pest animal management strategies are traditionally assessed for their effectiveness, with less consideration being given to the efficiency or cost of achieving the desired effect. I used cost-effectiveness analyses to compare between different baiting strategies based on the longevity, palatability and handling/replacement costs associated with each bait type. The results indicated that, when measured on a total cost-per-bait-consumed basis, wingettes and day-old chicks were the most cost-effective baits for campaigns of up to 4 weeks duration. This demonstrates the importance of including the longevity, and particularly the palatability of bait, when assessing cost-effectiveness. However, it is recognised that other factors, including the consistency of dosage and uptake by nontarget species, may be equally or more important in deciding the appropriate baiting strategy. The spatial and temporal application of fox baiting in the region overseen by the Molong Rural Lands Protection Board was examined between January 1998 and December 2002 as a case study to evaluate the apparent effectiveness of cooperative management practices. Most landholders (78.8%) did not bait for foxes during this period. Based on known dispersal distances, the effect of fox immigration into baited areas was determined. The results indicated that no areas baited for foxes were separated by a sufficient buffer distance (>9.58 km) from unbaited areas to be protected from fox immigration. This suggests that, at current levels of coordination, the effectiveness of most baiting operations in eastern Australia is compromised over the long term by fox immigration. However, it is recognised that short-term reductions in fox density may sometimes be all that are required to reduce predation to acceptable levels, especially for seasonally-susceptible prey. Ultimately, the cost-effectiveness of control should be evaluated in terms of the response of the prey rather than that of the predator. This study has highlighted deficiencies in current ‘best-practice’ baiting techniques. Specific recommendations for current baiting practices, in addition to future research, are also given. In brief, these include minimising free-feed baiting, increasing the minimum distance between bait stations, and, where possible, presenting the most palatable bait. Continued research into conditioned taste aversion, aerial baiting, and techniques to reduce caching are recommended as potential techniques to improve the efficiency of baiting practices

High-temperature sodium nickel chloride battery for electric vehicles

Although the sodium-nickel chloride cell couple has a high voltage (2.59 V) and a high specific energy (790 Wh/kg), the performance of present incarnations of this battery tend to be limited by their power. Because the nickel chloride electrode dominates the resistance and weight of the cell, research on this cell couple at Argonne National Laboratory (ANL) has been primarily directed toward improving both the specific power and energy of the NiCl{sub 2} electrodes. During the course of these investigations a major breakthrough was achieved in lowering the impedance and increasing the usable capacity through the use of chemical additives and a tailored electrode morphology. This improved Ni/NiCl{sub 2} electrode has excellent performance characteristics, wide-temperature operation and fast recharge capability. Modeling studies done on this electrode indicate that a fully developed Na/NiCl{sub 2} battery based on ANL-single tube and bipolar designs would surpass the mid-term and approach the long-term goals of the US Advanced Battery Consortium