Solar prominence modelling and plasma diagnostics at ALMA wavelengths

Our aim is to test potential solar prominence plasma diagnostics as obtained with the new solar capability of the Atacama Large Millimeter / submillimeter Array (ALMA). We investigate the thermal and plasma diagnostic potential of ALMA for solar prominences through the computation of brightness temperatures at ALMA wavelengths. The brightness temperature, for a chosen line of sight, is calculated using densities of hydrogen and helium obtained from a radiative transfer code under non local thermodynamic equilibrium (NLTE) conditions, as well as the input internal parameters of the prominence model in consideration. Two distinct sets of prominence models were used: isothermal-isobaric fine-structure threads, and large-scale structures with radially increasing temperature distributions representing the prominence-to-corona transition region. We compute brightness temperatures over the range of wavelengths in which ALMA is capable of observing (0.32 - 9.6mm), however we particularly focus on the bands available to solar observers in ALMA cycles 4 and 5, namely 2.6 - 3.6mm (Band 3) and 1.1 - 1.4mm (Band 6). We show how the computed brightness temperatures and optical thicknesses in our models vary with the plasma parameters (temperature and pressure) and the wavelength of observation. We then study how ALMA observables such as the ratio of brightness temperatures at two frequencies can be used to estimate the optical thickness and the emission measure for isothermal and non-isothermal prominences. From this study we conclude that, for both sets of models, ALMA presents a strong thermal diagnostic capability, provided that the interpretation of observations is supported by the use of non-LTE simulation results.Comment: Submitted to Solar Physic

Millimetre-continuum diagnostics and non-LTE radiative transfer modelling of solar prominences

With the advent of solar observing capability the Atacama Large Millimeter/sub-millimeter Array (ALMA), solar physicists now have access to high spatial resolution imaging of the millimetre-continuum emission from the solar atmosphere for the first time. The radiation in the wavelength range of ALMA is formed primarily through collisional processes, which, along with lying within the Rayleigh-Jeans Limit, results in a linear relationship between the brightness temperature and the electron temperature of the emitting plasma. Therefore, it is expected that millimetre observations have the potential for strong temperature diagnostics as well as other internal plasma parameters such as the emission measure. However, until ALMA the usefulness of millimetre-continuum observations has been hampered by low spatial resolutions. In this thesis I address the potential for the plasma diagnostics of solar prominences using ALMA. Solar prominences are an extreme example of natural magnetic confinement, where relatively high density, low temperature plasma is suspended within the sparse, extremely high temperature energetic solar corona. The term solar prominence generally refers to these structures when viewed off the solar limb, however, they are also observable, often as dark absorption features known as filaments, against the disk. These structures are maintained for long periods of time ranging from days to weeks through detailed energy balance. However, once this balance is broken solar prominences can erupt violently leading to dramatic events, often including Coronal Mass Ejections (CMEs). Understanding the formation, structure and energy balance of solar prominences is therefore an integral part in understanding solar atmospheric activity as a whole. To understand the formation of the millimetre-continuum from solar prominences I used the 2D non-Local Thermodynamic Equilibrium (non-LTE) cylindrical prominence code C2D2E of Gouttebroze & Labrosse (2009). This code considers a plasma consisting of both hydrogen and helium, with their ionization equilibrium. The use of a non-LTE model is important because, although the millimetre-continuum is formed from LTE processes, the ionization populations of the hydrogen and helium will be determined by non-LTE processes caused by incident ionizing and energising UV radiation. Considering sets of both isothermal–isobaric and multi-thermal prominence models including an ad-hoc prominence-to-corona transition region (PCTR) I calculated the emergent brightness temperature expected from solar prominences using the output from the C2D2E models. The results from the isothermal–isobaric models found that, whilst the optical thickness of a given millimetre wavelength is approximately > 4 - 5, the brightness temperature from the prominence at said wavelength equaled the constant electron temperature of the particular model. For the multi-thermal models it was found that the brightness temperature, whilst the plasma was optically thick, was representative of the electron temperature of a given formation layer within the particular line of sight (LOS). The formation layer was defined as the region/regions of each LOS with 70% the maximum contribution function for that LOS. When the material is optically thin the emergent brightness temperature is not representative of any unique layer within the prominence structure, but rather an integration across the entire temperature distribution within the LOS, with this integration also being affected by the optical thickness of the particular LOS. Therefore, in order to make assertions into the temperature structure from a solar prominence using millimetre-continuum diagnostics it is important to first have some understanding of the optical thickness regime of the emitting plasma. From the multithermal prominence models, of radius 1Mm, it was found that ALMA Band 3 produced a maximum optical thickness greater than 1 for pressures approximately > 0.1 dyn/cm^2, whilst Band 6 required pressures approximately > 0.5 dyn/cm^2. The millimetre-continuum prominence code was then altered to simulate the emergent brightness temperature from an on-disk filament observation. Again both isothermal–isobaric and multi-thermal PCTR filament models were considered, however, with the inclusion of various different background brightness temperatures from the solar disk. Using these models the visibility of filaments at ALMA Bands 3 and 6 is investigated by analysing their contrast against the background brightness temperature, with the inclusion of a discussion into how this may change with the inclusion of a “coronal cavity” above the overlying filament structure. A possible method to estimate the optical thickness of a plasma is by using coordinated observation of the same structure but in a different wavelength regime. I investigate correlations between the millimetre-continuum optical thickness and the integrated intensity from the important Lyman and Balmer lines of neutral hydrogen as well as the He I D3 line of neutral helium. The most important factor in determining the optical thickness of the millimetre-continuum is the charge squared weighted electron–ion emission measure. In this work a clear power-law relationship is found between the electron–proton emission measure and the integrated intensity of the Balmer lines, and between the electron–first ionized helium emission measure for the integrated intensity of the He I D3 line for isothermal–isobaric models. The brightness temperature of the millimetre–continuum is also found to produce a similar result to the colour temperature of the Lyman continuum when both are formed in near to overlapping formation regions. Other methods to determine the optical thickness of the millimetre-continuum investigated in this thesis include using analysis of the millimetre-continuum spectra. A relationship between the gradient of the logarithmic brightness temperature spectrum and the optical thickness of the millimetre-continuum at band-centre is derived. This relationship is then tested using sets of isothermal and multi-thermal 2D prominence models. A case study into using the gradient of the brightness temperature enhancement observed in a sub-band, science verification ALMA observation of an on-disk plasmoid eruption is presented. The method proves to be a strong candidate for estimating the optical thickness of the millimetre-continuum. However, it relies on a good understanding of the uncertainty into the brightness temperature measurement as well as the gradient of the background brightness temperature spectrum, which, due to the current state of understanding into the uncertainty of absolute brightness temperature measurements with ALMA, needed to be estimated in this study. In the final chapter of my thesis I present some preliminary results from the first high resolution interferometric observation of a solar prominence with ALMA. Coordinated observation with H alpha spectral imaging from the MSDP telescope in Białkow is used to estimate the optical thickness regime of prominence in the millimetre-continuum. A discussion into the morphology of the brightness temperature images of the prominence is provided as well as the correlations found between the brightness temperature distribution and the intensities from co-aligned images in each AIA band

Normalised Root Mean Square and Amplitude of Sidebands of Vibration Response as Tools for Gearbox Diagnosis

Quick assessment of the condition of gearboxes used in helicopters is a safety requirement. One of the most widely used helicopter on-board-mounted condition monitoring system these days is the Health and Usage Monitoring System. It has been specifically designed to monitor the condition of all safety-critical components operating in the helicopter through calculation of so-called condition indicators (CIs) - signal processing routines designed to output a single number that represents the condition of the monitored component. Among number of available parameters, there is a couple of CIs that over the years of testing have earned a reputation of being the most reliable measures of the gear tooth condition. At the same time, however, it has been observed that in some cases, those techniques do not properly indicate the deteriorating condition with the propagation of a gear tooth fault with the period of operation. Hence, three more robust methods have been suggested, which are discussed in this article

The Impact of Residence Design on Freshman Outcomes: Dormitories Versus Suite-Style Residences

This study was designed to measure affective, behavioural, and cognitive variables in a sample of 3159 first-year students, and to compare these variables by the type of residence building in which the student lived. Students living in suite-style buildings reported a greater sense of belonging, and higher activity levels than students living in dormitory- style buildings. Furthermore, sense of belonging was predicted by high extraversion and low conscientiousness. This suggests that introverted, conscientious students living in traditional dormitory-style buildings may be most at-risk of feeling “out-of-place” in residence.Cette étude a été crée pour évaluer les variables émotionnelles, comportementales, et cognitives dans une panel de 3159 étudiants dans leur première année d’université, et pour comparer ces variables par le type d’édifi ce de résidence dans laquelle les étudiantes vivaient. Etudiants vivant dans les immeubles de style suite ont rapporte un sens d’appartenance plus grand, et des niveaux plus élevées d’activité que celles qui vivait dans les immeubles de style foyer. En plus, un sens d’appartenance a été prédit par haute extraversion et des niveaux bas de conscience. Cela suggère que les étudiants introverties et consciencieux qui vivent dans les immeubles traditionnelles de style foyer seront peut-être les plus exposer à sentir « hors-de-place ». &nbsp

Expand+Functional selection and systematic analysis of intronic splicing elements identify active sequence motifs and associated splicing factors

Despite the critical role of pre-mRNA splicing in generating proteomic diversity and regulating gene expression, the sequence composition and function of intronic splicing regulatory elements (ISREs) have not been well elucidated. Here, we employed a high-throughput in vivo Screening PLatform for Intronic Control Elements (SPLICE) to identify 125 unique ISRE sequences from a random nucleotide library in human cells. Bioinformatic analyses reveal consensus motifs that resemble splicing regulatory elements and binding sites for characterized splicing factors and that are enriched in the introns of naturally occurring spliced genes, supporting their biological relevance. In vivo characterization, including an RNAi silencing study, demonstrate that ISRE sequences can exhibit combinatorial regulatory activity and that multiple trans-acting factors are involved in the regulatory effect of a single ISRE. Our work provides an initial examination into the sequence characteristics and function of ISREs, providing an important contribution to the splicing code

The Psychosocial Impact of Neurobehavioral Disability

Neurobehavioural disability (NBD) comprises elements of executive and attentional dysfunction, poor insight, problems of awareness and social judgement, labile mood, altered emotional expression, and poor impulse control, any or all of which can have a serious impact upon a person’s decision-making and capacity for social independence. The aim of this narrative review is to explore some of the more intrusive forms of NBD that act as obstacles to psychosocial outcome to act as a frame of reference for developing effective rehabilitation interventions. Special consideration is given to the psychosocial impact of three core forms of NBD: a failure of social cognition, aggressive behaviour, and problems of drive/motivation. Consideration is also given to the developmental implications of sustaining a brain injury in childhood or adolescence, including its impact on maturational and social development and subsequent effects on long-term psychosocial behaviour

Barriers to Education for the Marginalized Adult Learner

This qualitative study examines barriers to adult education by the marginalized adult learner. We adopted an inclusive approach by interviewing potential adult learners who had not participated in adult education programs due to illiteracy. Five overlapping themes related to barriers emerged and were categorized as: family values and responsibilities (i.e., cultural); the emotional effect of family poverty on participants’ lives (i.e., anger at the welfare system); disrupted school and learning experiences (i.e., multiple school changes); social exclusion and personal challenges (i.e., marginalization due to race, class); and turning points in participants’ education and hopes for the future (i.e., positive role models)

Timing of the first vancomycin maintenance dose in an acute hospital setting - room for improvement?

Introduction Intravenous vancomycin therapy typically starts with a loading dose followed by a maintenance dose 12 to 24 hours later. In the acute hospital setting, this often results in doses being administered in the middle of the night, which is impractical for both patients and staff. This audit examined current practice and developed new guidelines to support greater flexibility in the timing of the first maintenance dose. Methods Data recording forms used by pharmacists to support the therapeutic drug monitoring of vancomycin were collected from two hospital sites over six weeks. Forms containing at least two vancomycin concentrations were selected and the time of administration of the first maintenance dose was recorded. Individual vancomycin pharmacokinetic parameter estimates were obtained using MAP Bayesian analysis then used to predict vancomycin concentrations 6, 8, 10, 12 and 14 hours after a banded loading dose and 20 mg/kg (capped at 3000 mg). Predicted concentrations were compared with a target range of 10 – 20 mg/L. Results Data were obtained from 49 patients with a mean (SD) age of 63.1 (16.7) years and weight 80.1 (27.6) kg. In all patients, creatinine clearance estimates were >40 mL/min and, according to current practice guidelines, all patients required 12 hourly maintenance dosing. The time recorded for the administration of the first maintenance dose was between 11 pm and 7 am in 30 (61%) of these patients. In 14 patients (29%), the first maintenance dose was administered >12 hours after loading. The target range was achieved with banded doses (20 mg/kg) in 65% (71%) of concentrations at 6 hours, 74% (84%) at 8 hours, 57% (67%) at 10 hours, 53% (55%) at 12 hours and 39% (43%) at 14 hours. Conclusions This audit has shown that current practice results in a high proportion of vancomycin maintenance doses being administered at impractical times. Allowing a more flexible time window of 6-12 hours after the loading dose for administration of the first vancomycin maintenance dose could help to alleviate this problem and reduce the risk of early subtherapeutic vancomycin trough concentrations