Investigating the differential emission measure and energetics of microflares with combined SDO/AIA and RHESSI observations

An important question in solar physics is whether solar microflares, the smallest currently observable flare events in X-rays, possess the same energetic properties as large flares. Recent surveys have suggested that microflares may be less efficient particle accelerators than large flares, and hence contribute less nonthermal energy, which may have implications for coronal heating mechanisms. We therefore explore the energetic properties of microflares by combining Extreme Ultraviolet (EUV) and X-ray measurements. We present forward-fitting differential emission measure (DEM) analysis of 10 microflares. The fitting is constrained by combining, for the first time, high temperature RHESSI observations and flux data from SDO/AIA. Two fitting models are tested for the DEM; a Gaussian distribution and a uniform DEM profile. A Gaussian fit proved unable to explain the observations for any of the studied microflares. However, 8 of 10 events studied were reasonably fit by a uniform DEM profile. Hence microflare plasma can be considered to be significantly multi-thermal, and may not be significantly peaked or contain resolvable fine structure, within the uncertainties of the observational instruments. The thermal and non-thermal energy is estimated for each microflare, comparing the energy budget with an isothermal plasma assumption. From the multithermal fits the minimum non-thermal energy content was found to average approximately 30% of the estimated thermal energy. By comparison, under an isothermal model the non-thermal and thermal energy estimates were generally comparable. Hence, multi-thermal plasma is an important consideration for solar microflares that substantially alters their thermal and non-thermal energy content.Comment: 13 pages, 10 Figures, 2 tables. Accepted for publication in the Astrophysical Journa

Energy release in the solar atmosphere from a stream of infalling prominence debris

Recent high-resolution and high-cadence EUV imaging has revealed a new phenomenon, impacting prominence debris, where prominence material from failed or partial eruptions can impact the lower atmosphere, releasing energy. We report a clear example of energy release and EUV brightening due to infalling prominence debris that occurred on 2011 September 7-8. The initial eruption of material was associated with an X1.8-class flare from AR11283, occurring at 22:30 UT on 2011 September 7. Subsequently, a semi-continuous stream of this material returned to the solar surface with a velocity v > 150 km/s, impacting a region remote from the original active region between 00:20 - 00:40 UT on 2011 September 8. Using SDO/AIA, the differential emission measure of the plasma was estimated throughout this brightening event. We found that the radiated energy of the impacted plasma was L_rad ~10^27 ergs, while the thermal energy peaked at ~10^28 ergs. From this we were able to determine the mass content of the debris to be in the range 2x10^14 < m < 2x10^15 g. Given typical promimence masses, the likely debris mass is towards the lower end of this range. This clear example of a prominence debris event shows that significant energy release takes place during these events, and that such impacts may be used as a novel diagnostic tool for investigating prominence material properties.Comment: Accepted by AstroPhysical Journal Letters, 6 pages, 5 figure

Quasi-periodic pulsations in solar and stellar flares: re-evaluating their nature in the context of power-law flare Fourier spectra

The nature of quasi-periodic pulsations in solar and stellar flares remains debated. Recent work has shown that power-law-like Fourier power spectra, also referred to as 'red' noise processes, are an intrinsic property of solar and stellar flare signals, a property that many previous studies of this phenomenon have not accounted for. Hence a re-evaluation of the existing interpretations and assumptions regarding QPP is needed. Here we adopt a Bayesian method for investigating this phenomenon, fully considering the Fourier power law properties of flare signals. Using data from the PROBA2/LYRA, Fermi/GBM, Nobeyama Radioheliograph and Yohkoh/HXT instruments, we study a selection of flares from the literature identified as QPP events. Additionally we examine optical data from a recent stellar flare that appears to exhibit oscillatory properties. We find that, for all but one event tested, an explicit oscillation is not required in order to explain the observations. Instead, the flare signals are adequately described as a manifestation of a power law in the Fourier power spectrum, rather than a direct signature of oscillating components or structures. However, for the flare of 1998 May 8, strong evidence for the existence of an explicit oscillation with P ~ 14-16 s is found in the 17 GHz radio data and the 13-23 keV Yohkoh HXT data. We conclude that, most likely, many previously analysed events in the literature may be similarly described in terms of power laws in the flare Fourier power spectrum, without the need to invoke a narrowband, oscillatory component. As a result the prevalence of oscillatory signatures in solar and stellar flares may be less than previously believed. The physical mechanism behind the appearance of the observed power laws is discussed.Comment: 11 pages, 7 figures, 1 table. Accepted for publication in The Astrophysical Journa

Microtonal procedures in 'Sailing to Byzantium'

This short paper introduces and categorises the mictrotonal writing in my composition Sailing to Byzantium for solo recorder player (1999, published Chipping Norton 2016: Composers Edition). It was delivered at UK Microsoft 1 (Riverside Arts Centre, Walton-on-Thames, 15 October 2005), with live musical excerpts performed by Rachel Barnes. (In the text version of the paper these are rendered as musical illustrations from the manuscript facsimile score). Introductory material covers sources of inspiration for the piece and the use of microtones in it, including the poetry of W B Yeats, the Sequenzas of Luciano Berio, the communicable language of Olivier Messiaen, and Tibetan chant. Three categories of microtonal procedure are then identified: those used structurally using special alternative fingerings; 'bent' pitches used colouristically; and written-out glissandi. Six examples are provided in total, covering all three categories. Pitch-divisions are generally limited to quarter-tones, but eighth-tones are also deployed on occasion. Quarter-tone fingerings are based on Michael Vetter's Blockflütencshcule (Vienna 1983: Universal Edition); eighth-tone fingerings were extrapolated from Vetter's chart via an empirical process of trial-and-error

Market-orientated accounting: Information for product-level decisions

Purpose: The paper&#039;s purpose is to explore and describe the interface between the customer component of a market orientation and the accounting information used in making product-level decisions. Design/methodology/approach: Exploratory/descriptive organisational case study of a multi-function product decision-making setting. Development of a model of the customer-accounting information requirements of a market orientation. Findings: Describes how customer-orientated product decisions are guided by managers&#039; shared understanding of product-attributes and conceptions of a &#039;product&#039; as a &#039;bundle of attributes, benefits or characteristics&#039;. Describes the limited accounting function involvement in product-decisions and the use of customer-orientated and non-financial decision criteria. Practical implications: A market-orientated approach to business has been associated with increased business performance. The identification and integration of information from the management accounting discipline facilitates the understanding of the resource costs of satisfying individual customer needs and assists in operational level decisions. The authors highlight potential barriers to the integration of customer-orientated accounting information in product decisions. Originality/value: There remains a scarcity of marketing and management accounting interdisciplinary case research at the product-attribute decision-making level. The organisational study provides an insight into the decision-making information and processes at the market orientation and management accounting interface. A framework and suggestions for the further development of interfunctional product-level decision-making are provided

Biochemical Markers Predictive of Preterm Delivery

Preterm delivery is the leading cause of perinatal morbidity and mortality worldwide. Despite a great deal of research into this disease, we still do not understand its pathophysiology. Our treatments for this disease are only marginally effective. Biochemical markers were developed with the hope of giving us new tools to prevent preterm deliveries. Specifically the hope was that they could predict which patients were destined to have a preterm delivery. At the present time these markers perform only satisfactorily at predicting preterm labor. They are expensive and not convenient to use at present. Perhaps more importantly, though, these markers have given us insight into the complexities of preterm delivery. Preterm delivery can arise from many different etiologies. This will lead to research into new treatments as knowledge about preterm delivery is amassed. We know that any number of pathological processes may be involved in any given patient with preterm labor. Biochemical markers have the distinct advantage of being able to determine the specific pathophysiology in a given patient and may allow us to tailor therapy according to the specific problem. In the future it is likely that a careful search for specific pathophysiology will be the only way we can treat this disease effectively. For the present time the biochemical markers will be used only to predict preterm delivery. Ultrasound measurements of the cervix during the pregnancy are likely a faster and less expensive way to accomplish that goal

The Price of Consols

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