The high-energy Sun - probing the origins of particle acceleration on our nearest star

As a frequent and energetic particle accelerator, our Sun provides us with an excellent astrophysical laboratory for understanding the fundamental process of particle acceleration. The exploitation of radiative diagnostics from electrons has shown that acceleration operates on sub-second time scales in a complex magnetic environment, where direct electric fields, wave turbulence, and shock waves all must contribute, although precise details are severely lacking. Ions were assumed to be accelerated in a similar manner to electrons, but γ-ray imaging confirmed that emission sources are spatially separated from X-ray sources, suggesting distinctly different acceleration mechanisms. Current X-ray and γ-ray spectroscopy provides only a basic understanding of accelerated particle spectra and the total energy budgets are therefore poorly constrained. Additionally, the recent detection of relativistic ion signatures lasting many hours, without an electron counterpart, is an enigma. We propose a single platform to directly measure the physical conditions present in the energy release sites and the environment in which the particles propagate and deposit their energy. To address this fundamental issue, we set out a suite of dedicated instruments that will probe both electrons and ions simultaneously to observe; high (seconds) temporal resolution photon spectra (4 keV – 150 MeV) with simultaneous imaging (1 keV – 30 MeV), polarization measurements (5–1000 keV) and high spatial and temporal resolution imaging spectroscopy in the UV/EUV/SXR (soft X-ray) regimes. These instruments will observe the broad range of radiative signatures produced in the solar atmosphere by accelerated particles

Image-Derived Input Function for Human Brain Using High Resolution PET Imaging with [11C](R)-rolipram and [11C]PBR28

The aim of this study was to test seven previously published image-input methods in state-of-the-art high resolution PET brain images. Images were obtained with a High Resolution Research Tomograph plus a resolution-recovery reconstruction algorithm using two different radioligands with different radiometabolite fractions. Three of the methods required arterial blood samples to scale the image-input, and four were blood-free methods. values was quantified using a scoring system. Using the image input methods that gave the most accurate results with Logan analysis, we also performed kinetic modelling with a two-tissue compartment model.)-rolipram, which has a lower metabolite fraction. Compartment modeling gave less reliable results, especially for the estimation of individual rate constants.C]PBR28), the more difficult it is to obtain a reliable image-derived input function; and 4) in association with image inputs, graphical analyses should be preferred over compartmental modelling

Practitioners' perspectives and experiences of the new National Health Service dental contract

Background In April 2006, fundamental changes were made to the arrangements for commissioning state funded (National Health Service, NHS) dental care in England and Wales. These involved the dissolution of a universal national contract and the introduction of locally commissioned primary dental care services. Suggested advantages included the elimination of a fee-for-item 'treadmill', an increased emphasis on prevention and improved patient access. This change came at a time when many practitioners were opting to provide care outside the NHS. Objectives This study investigated dentists' experience of the new contract and compared this with attitudes determined in a previous survey of the same cohort of dentists conducted immediately before the changed commissioning arrangements. Methods Data were collected via a postal questionnaire, comprising a combination of 60 open and closed questions, mailed to 608 general dental practitioners in Wales. Results Four hundred and ninety-six (77%) questionnaires were returned. Four hundred and seventeen practitioners continued to provide NHS dental care. Only 46 (11%) of the 417 practitioners agreed that they liked the new method of remuneration and the majority (362[86.8%]) perceived that they still delivered state-funded care in a 'treadmill' environment. This compares with 34.9% of dentists who perceived the new system as a 'treadmill' immediately before its implementation. Three hundred and forty-eight (83.4%) disagreed that they were able to spend more time on prevention and 356 (85.3%) did not feel they had more time to spend with patients-key objectives of the reforms. Two hundred and seventy-five (65.9%) respondents agreed that local NHS commissioners were controlling their business. Conclusion This survey, conducted 18 months after the implementation of the new commissioning arrangements, suggests that practitioners are deeply unhappy with local commissioning. It raises questions as to whether the changes have achieved the Government's stated objectives in reforming state-funded primary dental care

Infant brain subjected to oscillatory loading: material differentiation, properties, and interface conditions

Past research into brain injury biomechanics has focussed on short duration impulsive events as opposed to the oscillatory loadings associated with Shaken Baby Syndrome (SBS). A series of 2D finite element models of an axial slice of the infant head were created to provide qualitative information on the behaviour of the brain during shaking. The test series explored variations in subarachnoid cerebrospinal fluid (CSF) representation, brain matter stiffness, dissipation, and nonlinearity, and differentiation of brain matter type. A new method of CSF modelling based on Reynolds lubrication theory was included to provide a more realistic brain–CSF interaction. The results indicate that solid CSF representation for this load regime misrepresents the phase lag of displacement, and that the volume of subarachnoid CSF, and inclusion of thickness variations due to gyri, are important to the resultant behavior. Stress concentrations in the deep brain are reduced by fluid redistribution and gyral contact, while inclusion of the pia mater significantly reduces cortex contact strains. These results provide direction for future modelling of SBS