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Since the 1950s, Tolles-Lawson-based aeromagnetic compensation methods have been used to separate an aircraft's magnetic signal from signal associated with ground geologic and cultural features. This is done by performing a high-altitude figure-of-merit (FOM) flight and fitting the band-pass-filtered magnetic data to determine compensation parameters. This paper describes a supervised hybrid recurrent neural network (HRNN) algorithm trained on low-altitude survey data to perform aeromagnetic compensation. The proposed HRNN attitude compensation method can be employed for aeromagnetic surveys where traditional FOM and compensation are not possible. It has particular relevance for surveying via uninhabited aircraft systems (UAS). Firstly, the HRNN was tested on data from a fixed-wing airplane survey, and the results were compared to hardware-based compensation results. The standard deviation of the difference between the two methods for magnetic attitude correction (MAC) was 0.1 nT for the training region and 0.4 nT for the application region, respectively. Secondly, a UAS FOM flight at the highest permitted altitude in Canada, 120 m above ground level, showed similar improvement ratios for software-based least squares (LS) and the proposed HRNN algorithm of 3.5 and 2.6, respectively. The percent change and deviation in differences in MACs from LS to HRNN was 0.0% and 0.9 nT across small-box loops and –2.7% and 0.4 nT across large-box loops. Finally, LS and the proposed HRNN algorithm were applied to a 50 m altitude UAS data set for which no FOM flight was possible. LS did not successfully model aircraft noise, whereas the HRNN demonstrated effective removal of the magnetic signal due to aircraft attitude variations. The modeled HRNN MAC had a standard deviation of 2.4 nT.

Non-linear couplings of the Earth’s ionosphere with the geospace environment occur in a largely varying range of spatial and temporal scales. As some radio remote sensing techniques like GNSS measurements suffer from artificial radio frequency interference (RFI) at the smallest scales representing ionospheric scintillation, is it advantageous to have ionospheric scales observations based on in-situ measurements.We investigated the variability of the in-situ plasma density and magnetic field measured by Swarm satellites creating the climatology of their scales by leveraging the Fast Iterative Filtering (FIF) technique.FIF is able to provide a very fine time-frequency representation decomposing any non-stationary, nonlinear signals, into oscillating modes, called intrinsic mode components or functions (IMCs or IMFs), characterized by their specific frequency.The results are obtained by time-integrating the instantaneous time-frequency representations, provided through the so-called “IMFogram”. These IMFograms have the potential to show the greater details of the scale sizes and their variations, illustrating the time development of the multi-scale processes during various disturbances of geospace.

The Low Frequency Array (LOFAR) is designed to observe the early universe at radio wavelengths. When radio waves from a distant astronomical source traverse the ionosphere, structures in the plasma affect the signal. The high temporal resolution available (~10 ms), the large range of frequencies observed (10-80 MHz & 120-240 MHz) and the large number of receiving stations (currently 52 across Europe) mean that LOFAR can observe the effects of the midlatitude ionosphere in an unprecedented level of detail.The observational programme LT16_002 began in September 2021 and observations from the first 15 months of this programme are used to investigate ionospheric structures. A variety of patterns in the received signal intensity have been observed. Some of these appear to be similar to features reported previously, such as Spectral Caustics seen in solar observations (Koval et al., 2017) using the Nançay Decametric Array, as well as observations inferred from LOFAR of Travelling Ionospheric Disturbances (TIDs) at large- and medium-scales (Fallows et al., 2020), small scale TIDs (Boyde et al., 2022) and sporadic E (Wood et al., 2022). Other structures appear to be previously unreported. Collectively, we refer to these structures as Radio Alteration Features (RAFs).In order to investigate the occurrence and origin of RAFs, 1092 hours of observations from LT16_002 were analysed. If the intensity of the received signal rose to 20% above the median value for the observation in a given hour then, within this study, this hour was classified as containing a RAF. RAFs were observed in 382 hours of observations. RAFs are primarily a night-time phenomenon and are more common in summer. They do not appear to have a statistically-significant relationship to geomagnetic activity as measured by a variety of geomagnetic indices, but there is some evidence that they are more common during times of enhanced solar activity or when a CME encounters the Earth.Work on a measure of the strength of the RAFs is underway using the amplitude scintillation index S4. New observations from LT16_002 mean that the database is continually expanding. Comparisons of the climatology of RAFs to the climatology of other features, such as TIDs, is planned to give an insight into the driving processes. The latest developments in this work will be reported.ReferencesBoyde, B., Wood, A. G., Dorrian, G. D., Fallows, R. A., Themens, D. R., et al. (2022). Lensing from small-scale travelling ionospheric disturbances observed using LOFAR. J. Space Weather Space Clim. 12, 34. https://doi.org/10.1051/swsc/2022030.Fallows, R. A., et al. (2020), A LOFAR Observation of Ionospheric Scintillation from Simultaneous Medium- and Large-scale Travelling Ionospheric Disturbances, J. Space Weather Space Clim. doi.org/10.1051/swsc/2020010.Koval, A., et al. (2017), Traveling ionospheric disturbances as huge natural lenses: Solar radio emission focusing effect, J. Geophys. Res. Space Physics, 122, 9092–9101, doi:10.1002/2017JA024080.Wood, A. G., Dorrian, G. D., Boyde, B. and Fallows, R. A. (2022), Terrestrial drivers of rapidly changing plasma structures observed with the International LOFAR Telescope, 3rd URSI AT-AP-RASC.

The 16 Hz plasma density measurements provided by the high-resolution faceplate onboard Swarm satellites can be utilized to reconstruct the one-dimensional spectral slope (p) of the power spectrum of the plasma density irregularity. The 16 Hz sampling rate at Swarm orbital features (speed of ~7.5 km/s on quasi-polar orbits) allows modelling spatial scales of about 500 m along the flight trajectory, which are slightly above the first Fresnel zone, the upper limit of the scale sizes of the irregularities causing scintillation on Global Navigation Satellite Systems (GNSS) signals. The p-value is a key parameter in estimating the scintillation strength and thus a Swarm ionospheric scintillation (SWIS) proxy is investigated. Such approach, once consolidated, will benefit the scientific community in studying, monitoring and modelling the small-scale irregularities; specially in contexts where ground based GNSS scintillation monitoring is not available, for example over the oceans.In this work, p-value from Swarm, combined with the reconstruction of the irregularity layer , are ingested to compute the amplitude scintillation index (S4) using Rino’s theory of weak scattering. In this work, the model formulation and sample results of S4 estimation from Swarm are demonstrated. Results of validating SWIS S4 against S4 from ground based GNSS scintillation for selected key ionospheric sectors are also shown. The results demonstrate that the model can capture the amplitude scintillation index inflation both at low and high latitudes, demonstrating the capability of detecting the equatorial and the (rare) polar amplitude scintillation from Swarm measurements.

Observations made using the LOw Frequency ARray (LOFAR) between 10:15 and 11:48 UT on the 15th of September 2018 over a bandwidth of approximately 25-65 MHz contain discrete pseudo-periodic features of ionospheric origin. These features occur with a period of approximately ten minutes and collectively last roughly an hour. They are strongly frequency dependent, broadening significantly in time towards the lower frequencies, and show an overlaid pattern of diffraction fringes. By modelling the ionosphere as a thin phase screen containing a wave-like disturbance, we are able to replicate the observations, suggesting that they are associated with small-scale travelling ionospheric disturbances (TIDs). This modelling indicates that the features observed here require a compact radio source at a low elevation, and that the TID or TIDs in question have a wavelength ~30 km. Several features suggest the presence of deviations from an idealised sinusoidal wave form. These results demonstrate LOFAR's capability to identify and characterise small-scale ionospheric structures.

A hexacopter unmanned aircraft system instrumented with a caesium vapour magnetometer recorded total magnetic intensity over a 5.0 km2 prospective gold area in the Abitibi Subprovince of the Canadian Precambrian Shield. The survey also included a N–S repeatability line which showed that the unmanned aircraft system was very stable in flight with average standard deviations from nominal altitude and easting being 1.8 m and 0.7 m, respectively. The total magnetic intensity map revealed the structural framework of the banded iron formations present in the survey area and showed that the gold ore zones are not directly associated with magnetic highs but rather with steeply dipping faults. The total magnetic intensity data was inverted in 3-D using unconstrained and constrained approaches with 12.5 m (northing) × 12.5 m (easting) × 5 m (depth) cells and a maximum of 20 iterations. The processed (after diurnal corrections, heading correction, and tie-line levelling) total magnetic intensity data was input directly in the unconstrained inversion algorithm. Initial model building for the constrained inversion was a much more laborious process involving the inclusion of 15 synthetic structures based on borehole magnetic susceptibility measurements and knowledge of the local geology. The results of both inversion approaches were very similar. They revealed the presence of near-vertical thin sheets, individually resolvable down to approximately 400 m. In this particular case, the straightforward unconstrained inversion yielded a realistic and detailed model of the subsurface in approximately 1 h of runtime. Unmanned aircraft system total magnetic intensity data could therefore be processed and inverted almost immediately after acquisition and have an impact on decisions made in the field while a survey is still in progress.

Polar holes were observed in the high-latitude ionosphere during a series of multi-instrument case studies close to the Northern Hemisphere winter solstice in 2014 and 2015. These holes were observed during geomagnetically quiet conditions and under a range of solar activities using the European Incoherent Scatter (EISCAT) Svalbard Radar (ESR) and measurements from Global Navigation Satellite System (GNSS) receivers. Steep electron density gradients have been associated with phase scintillation in previous studies; however, no enhanced scintillation was detected within the electron density gradients at these boundaries. It is suggested that the lack of phase scintillation may be due to low plasma density levels and a lack of intense particle precipitation. It is concluded that both significant electron density gradients and plasma density levels above a certain threshold are required for scintillation to occur.

The ionosphere is a dynamical system exhibiting nonlinear couplings with the other “spheres” characterizing the geospace environment. Such nonlinearity manifests also through the non-trivial, largely varying range of spatial and temporal scales. We investigate how the different scales of the in situ plasma density as provided by different data products measured by Swarm satellites relate to the same range of scales of the field-aligned currents from Swarm FAC dataset and how their intensifications reflect the various conditions of the geospace.The present study compares the spatio-temporal variability in the topside ionosphere by leveraging on the Fast Iterative Filtering (FIF) technique. FIF is able to reveal the hidden features of a time series, as it decomposes any nonstationary, nonlinear signals, like those provided by Langmuir probes onboard Swarm, into oscillating modes, called intrinsic mode components or functions (IMCs or IMFs), characterized by their specific frequencies. The instantaneous time-frequency representation of the IMFs is provided through the so-called “IMFogram” which illustrates the time development of the multi-scale processes. The IMFogram has the potentiality to show the finer details of the scale sizes which intensify during the various phases of geomagnetic storms.This work is performed in the framework of the Swarm Variability of Ionospheric Plasma (Swarm-VIP) project, funded by ESA in the “Swarm+4D-Ionosphere” framework (ESA Contract No. 4000130562/20/I-DT).

Statistical models have been developed for predicting the behavior of the coupled high‐latitude ionosphere‐thermosphere system. The modeled parameters were the F‐layer peak electron density, plasma structuring, ion temperature, neutral temperature, and the difference between these temperatures, which is a key term in the Joule heating equation. Ionospheric measurements from the European Incoherent Scatter Svalbard Radar and neutral atmosphere measurements from the colocated University College London Fabry‐Perot Interferometers have been made across a solar cycle. These data were all acquired during nighttime conditions as the observations with the Fabry‐Perot Interferometers are restricted to such times. Various geophysical proxies were tested to represent the processes that influence the modeled parameters. The dominant geophysical proxy for each modeled parameter was then determined. Multivariate models were also developed showing the combinations of parameters that best explained the observed variability. A comparison with climatology showed that the models give an improvement in every case with skill scores based on the mean square error of up to 0.88.

Flow channel events have previously been observed breaking up polar cap patches on the dayside ionosphere but, to the best of our knowledge, have not been observed on the nightside. We report observations of a flow channel event in the evening of the 9th January 2019 under quiet geomagnetic conditions. This multi-instrument study was undertaken using a combination of multiple EISCAT (European Incoherent Scatter) radars, SuperDARN (Super Dual Auroral Radar Network), MSP (Meridian Scanning Photometer) and GNSS (Global Navigation Satellite System) scintillation data. These data were used to build a picture of the evening’s observations from 1800 to 2359 UT. The flow channel event lasted a total of 13 minutes and was responsible for segmenting a polar cap patch. A decrease in electron density was observed, from a patch value of 1.4x1011 m3 to a minimum value of 5x1010 m3. In addition, ion velocities in excess of 1000 ms-1 and ion temperatures of greater than 2000 K were also observed.

In the UK, the primary route to a physics degree is through studying for advanced level qualifications (known as A-levels) in both physics and mathematics. 38,958 students were entered for A-level examinations in physics in 2019, with the majority of these candidates also entered for A-level mathematics.In recent years the UK has seen a growth of vocational, technical and wide entry qualifications. The vocational and technical qualifications are targeted at teenagers, and the latter targeting mature students returning to education later in life. These qualifications all cover a wider breadth of material, but in less depth than traditional A-levels. In order to ensure that these students can succeed at a physics degree, Nottingham Trent University developed a new course, BSc Applied Physics.BSc Applied Physics is designed to follow on directly from vocational, technical and wide entry courses, including the BTEC Extended Diploma in Applied Science and Diplomas in Access to Higher Education. In the first year of BSc Applied Physics students have extra workshops to support their studies, and extra sessions on mathematics for physics. The aim is that, at the end of the first year, these students should have the same mathematical ability as year 1 students on our main BSc Physics course. The BSc Applied Physics students then have a choice. They can either continue with BSc Applied Physics, which focusses on the applications of physics, or transfer to a more traditional BSc Physics programme.The purpose of this poster is to showcase to teachers how this type of non-standard degree programme can benefit students studying for non-traditional qualifications.

The LOFAR (Low Frequency Array) is one of the world’s leading radio telescopes, operating across the frequency band 10-250 MHz. As radio waves from astronomical sources pass through the ionosphere, they can undergo refraction and/or diffraction. The variations in the intensity of the received signal are caused by irregularities with a spatial scale size ranging from the Fresnel dimension to an order of magnitude below this value. The received signal can therefore be used to infer information on plasma structures in the ionosphere. As the frequencies used are significantly lower than the 1.4 GHz typically associated with Global Navigation Satellite Systems (GNSS), the plasma structures that affect the signals received by LOFAR are significantly larger, typically of the order of kilometres.On 14th July 2018 the Dutch stations of LOFAR observed the strong natural radio sources Cassiopeia A and Cygnus A between 17:00 UT and 18:05 UT at a frequency range of 20-80 MHz. During the observation, the signal intensity received by many of the stations underwent a substantial reduction across all frequencies, lasting approximately 10 minutes. Immediately before and after this, periodic enhancements in the signal strength were observed. These enhancements showed a noticeable frequency dependence, with longer period oscillations at lower frequencies. The feature was not observed simultaneously by the stations and evolved during the observations. Such a feature is most likely to be the result of a large-scale density structure in the ionosphere, which appears to move west and north over the northern Netherlands.The deep fading of the received signal may be due to the presence of sporadic-E, which is a consequence of variations in the neutral wind speed with altitude in the presence of the geomagnetic field, resulting in plasma accumulating in a thin layer. This can cause incident radio waves to be strongly refracted, affecting the strength of the received signal. The wave-like structure immediately before and after the deep fade is a likely consequence of scattering of the observed signal.

Unmanned aircraft systems (UASs) have been under rapid development for applications in the mineral exploration industry, mainly for aeromagnetic surveying. They provide improved detection of smaller, deeper and weaker magnetic targets. A traditional system flying an altitude of 100 m above ground level (AGL) can detect a spherical ore body with a radius of ~ 16 m and a magnetic susceptibility of 10−4 buried at a depth of 40 m. A UAS flying at an altitude of 50 or 2 m AGL would require the radius to be 11 or 5 m, respectively. A demonstration survey was performed using the SkyLance rotary-wing UAS instrumented with a cesium vapour magnetometer in Nash Creek, New Brunswick, Canada. The UAS flew over a zinc deposit featuring three magnetic anomalies. It acquired repeatable data that compared well with upward continuation maps of ground magnetic data. Dykes or faults that are dipping eastward at 25° and are approximately 1.5 m wide fit the observed response of the three anomalies captured on the UAS magnetic data.

Currently, Stratus Aeronautics is developing an unmanned aircraft system (UAS), called the Venturer, for aeromagnetic surveying. On 2 October 2013, in southern Alberta, Canada, an experimental survey of the UAS was conducted. Approximately 13 km of preprogrammed survey lines, along with calibration maneuvers, were flown, providing 45 minutes worth of data collection. The UAS was stable in flight and only required operator intervention for takeoff and landing. There was a + 2 m offset from the nominal altitude of 150 m, with variations of approximately ± 1.4 m. Deviations from a straight flight path were approximately ± 0.9 m along traverse lines and ± 25 m along tie-lines, the latter being affected mainly by crosswind. The noise envelope for the magnetic data acquired during the survey was approximately ± 0.05 nT, allowing a high-quality total-magnetic-intensity map to be created.

This chapter is focussing on the interaction of arsenic, mercury and selenium with plans. Aspects of biotransformations are discussed, before the analytical methodologies are listed and critically appraised in the second part. A holistic view is given, starting from the soil environment and continuing to the plant roots and the translocations into the upper part of the plants. Under different soil conditions, different kinds of elemental species are identified, which have an impact on how the elemental species are taken up by the plant. The uptake mechanisms of these elemental species are explained and compared before the biotransformation reactions of all elemental species in the plant root; their transport into the vacuoles and translocation to the leaves and grains are discussed. Here in particular the interaction with sulphur-rich phytochelatins is described for all three elemental species. Since the sulphur chemistry is so important for the uptake, bioaccumulation and translocation of the metals and metalloids, a subchapter about sulphur chemistry in plants has been added. All aspects of biotransformation dealt with in this chapter is finally rounded up by a thorough description of the analytical methodology given with a focus on the use of HPLC-ICPMS/ESI-MS for both quantitative and molecular analysis.

This chapter is focussing on the interaction of arsenic, mercury and selenium with plans. Aspects of biotransformations are discussed, before the analytical methodologies are listed and critically appraised in the second part. A holistic view is given, starting from the soil environment and continuing to the plant roots and the translocations into the upper part of the plants. Under different soil conditions, different kinds of elemental species are identified, which have an impact on how the elemental species are taken up by the plant. The uptake mechanisms of these elemental species are explained and compared before the biotransformation reactions of all elemental species in the plant root; their transport into the vacuoles and translocation to the leaves and grains are discussed. Here in particular the interaction with sulphur-rich phytochelatins is described for all three elemental species. Since the sulphur chemistry is so important for the uptake, bioaccumulation and translocation of the metals and metalloids, a subchapter about sulphur chemistry in plants has been added. All aspects of biotransformation dealt with in this chapter is finally rounded up by a thorough description of the analytical methodology given with a focus on the use of HPLC-ICPMS/ESI-MS for both quantitative and molecular analysis.

Capabilities are a more scalable and adaptive access control approach compared with the conventional approaches such as ACLs, due to their being held and managed by users or agents in systems, but not the middleware. This feature makes capabilities more suitable in distributed environments that have dynamic populations. Treaties have been proposed to enhance the capability approach by introducing sequences of actions, such that treaties can capture characteristics of behaviours, and provide finer control over accesses. However there is a new problem brought by the behaviour modeling of treaties which is called duplication problem, which concerns preventing users from gaining unauthorized behaviour by duplicating treaties. In this paper we provide the formal definitions of treaty operations, and discuss the causes of the duplication problem, and how treaty operations can affect this. We also propose three models of treaty systems that aim to solve the duplication problem, and evaluating their performance and scalability.

Reliable predictive accident models (PAMs) (also referred to as safety performance functions (SPFs)) are essential to design and maintain safe road networks however, ongoing changes in road and vehicle design coupled with road safety initiatives, mean that these models can quickly become dated. Unfortunately, because the fitting of sophisticated PAMs including a wide range of explanatory variables is not a trivial task, available models tend to be based on data collected many years ago and seem unlikely to give reliable estimates of current accidents. Large, expensive studies to produce new models are likely to be, at best, only a temporary solution. This paper thus seeks to develop a practical and efficient methodology to allow currently available PAMs to be updated to give unbiased estimates of accident frequencies at any point in time. Two principal issues are examined: the extent to which the temporal transferability of predictive accident models varies with model complexity; and the practicality and efficiency of two alternative updating strategies. The models used to illustrate these issues are the suites of models developed for rural dual and single carriageway roads in the UK. These are widely used in several software packages in spite of being based on data collected during the 1980s and early 1990s. It was found that increased model complexity by no means ensures better temporal transferability and that calibration of the models using a scale factor can be a practical alternative to fitting new models.

Reliable predictive accident models (PAMs) are essential to design and maintain safe road networks, and yet the models most commonly used in the UK were derived using data collected 20 to 30 years ago. Given that the national personal injury accident total fell by some 30% in the last 25 years, while road traffic increased by over 60%, significant errors in scheme appraisal and evaluation based on the models currently in use seem inevitable. In this paper, the temporal transferability of PAMs for modern rural single carriageway A-roads is investigated, and their predictive performance is evaluated against a recent data set. Despite the age of these models, the PAMs for predicting the total accidents provide a remarkably good fit to recent data and these are more accurate than models where accidents are disaggregated by type. The performance of the models can be improved by calibrating them against recent data.

We report a retired, Afro-Caribbean man aged 69 years who presented to his local hospital with several weeks of dyspnoea and cough. Physical examination was unremarkable apart from an elevated jugular venous pressure and a bilateral pedal oedema. His medical history included asthma and controlled hypertension. Urgent transthoracic echocardiography showed a large soft tissue mass in the pericardial space compressing the right ventricle (RV), and the right atrium (RA). A CT of the thorax showed a mass measuring 16 cm in width by 8 cm in depth with infiltration and compression of RV and RA with distortion of atrioventricular …

Whilst there are a variety of methods available for the quantification of biothiols in sample extracts, each has their own inherent advantages and limitations. The ease with which thiols readily oxidise not only hinders their quantification but also alters the speciation profile. The challenge faced by the analyst is not only to preserve the speciation of the sample, but also to select a method which allows the retrieval of the desired information. Given that sulfur is not a chromophore and that it cannot easily be monitored by ICP-MS, a number of direct and indirect methods have been developed for this purpose. In order to assess these methods, they are compared in the context of the measurement of arsenic-phytochelatin complexes in plant extracts. The inherent instability of such complexes, along with the instabilities of reduced glutathione and phytochelatin species,necessitates a rapid and sensitive analytical protocol. Whilst being a specific example, the points raised and discussed in this review will also be applicable to the quantification of biothiols and thiol-metal(loid) species in a wide range of systems other than just the analysis of arsenic-phytochelatin species in plant extracts.