Twisting Flux Tubes as a cause of Micro-Flaring Activity

High-cadence optical observations of an H-alpha blue-wing bright point near solar AR NOAA 10794 are presented. The data were obtained with the Dunn Solar Telescope at the National Solar Observatory/Sacramento Peak using a newly developed camera system, the Rapid Dual Imager. Wavelet analysis is undertaken to search for intensity-related oscillatory signatures, and periodicities ranging from 15 to 370 s are found with significance levels exceeding 95%. During two separate microflaring events, oscillation sites surrounding the bright point are observed to twist. We relate the twisting of the oscillation sites to the twisting of physical flux tubes, thus giving rise to reconnection phenomena. We derive an average twist velocity of 8.1 km/s and detect a peak in the emitted flux between twist angles of 180 and 230 degrees.Comment: 8 pages, 10 figure

Examining the role of Scotland’s telephone advice service (NHS 24) for managing health in the community : analysis of routinely collected NHS 24 data

Date of Acceptance: 15/06/2015 Funding This work was supported by the Chief Scientist Office, ScottishExecutive (grant no. CZH/4/692). Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.Peer reviewedPublisher PD

Nitration of primary amines to form primary nitramines (Review)

Poster presentation at 19th Seminar on New Trends in Research of Energetic Materials; Pardubice, Czech Republic; 20/04/2016-22/04/2016The nitration of primary amines to form primary nitramines is a rarely reported synthetic procedure which proceeds through a minimum of two steps. This is in stark contrast to the nitration of alcohols and secondary amines which is readily achievable by a number of methods in a single step. In general the primary amine must initially be activated to nitration as direct exposure to nitrating media tends to result in the formation of an ionic nitrate salt. This activation may be achieved through the use of a multitude of protecting groups that are stable to the nitrating conditions used thereafter. The review presented here is an attempt to bring together the published literature on this often overlooked synthetic procedure in energetic materials chemistry

Hyperplasia and Fluid Accumulation in Epithelial Cyst Formation and Growth

Epithelial cysts may develop in virtually any epithelium. All cysts, regardless of their origins, are characterized by epithelial hyperplasia and fluid accumulation. Additional features may include tubular atrophy, basement membrane alterations and association with inflammatory cells. In spite of the intense research effort in recent years directed at uncovering the cellular mechanisms of cyst development and growth, we still do not know the primary events that lead to cyst formation. However, there are at least three candidate mechanisms. These include: 1) increased cell proliferation (epithelial hyperplasia) in the cyst wall, 2) net fluid accumulation in the cyst cavity and 3) alterations of extracellular matrix components linked to cyst formation and growth. This review discusses the evidence to support the role of each mechanism as a possible primary event necessary for cyst initiation and continued enlargement. Present data on the pathogenesis of epithelial cyst formation strongly suggests that no single mechanism, as yet described, can adequately account for all situations of cyst occurrence

Discovery of spatial periodicities in a coronal loop using automated edge-tracking algorithms

A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. Applying this technique to TRACE data, obtained using the 171 Å filter on 1998 July 14, we detect a coronal loop undergoing a 270 s kink-mode oscillation, as previously found by Aschwanden et al. However, we also detect flare-induced, and previously unnoticed, spatial periodicities on a scale of 3500 km, which occur along the coronal loop edge. Furthermore, we establish a reduction in oscillatory power for these spatial periodicities of 45% over a 222 s interval. We relate the reduction in detected oscillatory power to the physical damping of these loop-top oscillations

The Influence of Magnetic Field on Oscillations in the Solar Chromosphere

Two sequences of solar images obtained by the Transition Region and Coronal Explorer in three UV passbands are studied using wavelet and Fourier analysis and compared to the photospheric magnetic flux measured by the Michelson Doppler Interferometer on the Solar Heliospheric Observatory to study wave behaviour in differing magnetic environments. Wavelet periods show deviations from the theoretical cutoff value and are interpreted in terms of inclined fields. The variation of wave speeds indicates that a transition from dominant fast-magnetoacoustic waves to slow modes is observed when moving from network into plage and umbrae. This implies preferential transmission of slow modes into the upper atmosphere, where they may lead to heating or be detected in coronal loops and plumes.Comment: 8 pages, 6 figures (4 colour online only), accepted for publication in The Astrophysical Journa

Compatibility assessment of thermoplastic formulations

Presented at 19th Seminar on new trends in research of energetic materials (NTREM 2016)Prior to the large-scale preparation of any new chemical formulation an assessment of the potential reactivity between the components must be carried out. This practice, which is common to many fields including pharmaceutical science, is particularly essential in the case of energetic formulations whose chemical incompatibility may result in an unexpected and potentially explosive decomposition. The common method used to investigate incompatibility is to heat 1:1 (w/w) formulations and evaluate the variation in their thermal stability with respect to the neat, pristine explosive. The techniques used are: differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), vacuum stability and heat flow calorimetry. As trends in energetics move towards safer formulations the components are more commonly selected for their high thermal stability and low sensitivity to initiation. However, recently prepared thermoplastic formulations which incorporate a thermally stable explosive, 2,2’,4,4’,6,6’-hexanitrostilbene (HNS II), and a selection of high-melting-point thermoplastics produced anomalous results during their compatibility assessment leading to the suggestion that historical tests originally devised for less thermally stable materials, such as N,N’,N’’-trinitro-1,3,5-triazacyclohexane (RDX), may not be directly transferable to the newer generations of insensitive explosive formulations

Network oscillations at the boundary of an equatorial coronal hole

We investigate intensity oscillations observed simultaneously in the quiet chromosphere and in the corona, above an enhanced network area at the boundary of an equatorial coronal hole. A Fourier analysis is applied to a sequence of images observed in the 171 A and 1600 A passbands of TRACE. Four interesting features above the magnetic network are further investigated by using a wavelet analysis. Our results reveal that, in both the 171 A and 1600 A passbands, oscillations above the magnetic network show a lack of power at high frequencies (5.0-8.3 mHz), and a significant power at low (1.3-2.0 mHz) and intermediate frequencies (2.6-4.0 mHz). The global 5-min oscillation is clearly present in the 4 analyzed features when seen in the 1600 A passband, and is also found with enhanced power in feature 1 (leg of a large coronal loop) and feature 2 (legs of a coronal bright point loop) when seen in the 171 A passband. Two features above an enhanced network element (feature 3 and feature 4) show repeated propagating behaviors with a dominant period of 10 min and 5 min, respectively. We suggest these oscillations are likely to be slow magneto-acoustic waves propagating along inclined magnetic field lines, from the lower solar atmosphere into the corona. The energy flux carried by these waves is estimated of the order of 40 erg cm\^{-2} s\^{-1} for the 171 A passband and is far lower than the energy required to heat the quiet corona. For the 1600 A passband, the energy flux is about 1.4*10^6 erg cm\^{-2} s\^{-1}, which is about one third of the required energy budget for the chromosphere.Comment: 7 pages, 8 figure

Solar feature tracking in both spatial and temporal domains

A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. The reliability of this technique was tested with TRACE 171A observations. The application of this technique to a flare-induced kink-mode oscillation, revealed a 3500 km spatial periodicity which occur along the loop edge. We establish a reduction in oscillatory power, for these spatial periodicities, of 45% over a 322 s interval. We relate the reduction in oscillatory power to the physical damping of these loop-top oscillations

Polarized Epithelial Cysts in vitro: A Review of Cell and Explant Culture Systems that Exhibit Epithelial Cyst Formation

The purpose of this paper is to review in vitro cell and explant culture systems that exhibit epithelial cyst formation and that are used as models of polarized epithelial function. We examine a number of culture systems derived from a variety of cell and organ types, briefly describe the methodology and conditions used to establish these cultures and discuss aspects of the experimental application of each system. We conclude that the characteristics of epithelial cyst-forming cultures are dependent upon the origin and identity of the cell population, as well as the multiple factors that define the culture environment. Culture systems in which epithelial cyst development occurs provide tools to study fundamental problems in epithelial biology, such as the establishment and maintenance of cell polarity, cell recognition and cell sorting, also cell-specific functions involving solute and water transport and the production and modification of secreted products. In addition, epithelial cyst culture systems offer useful models to better understand cellular behavior in various pathologic conditions of cyst formation in man