Keele University

About: Keele University is a education organization based out in Newcastle-under-Lyme, United Kingdom. It is known for research contribution in the topics: Population & Stars. The organization has 11318 authors who have published 26323 publications receiving 894671 citations. The organization is also known as: Keele University.

Evidence for ultra-fast outflows in radio-quiet AGNs: III - location and energetics

Abstract: Using the results of a previous X-ray photo-ionization modelling of blue-shifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this letter we estimate the location and energetics of the associated ultra-fast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval ~0.0003-0.03pc (~10^2-10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are constrained between ~0.01-1 M_{\odot} yr^{-1}, corresponding to >5-10% of the accretion rates. The average lower-upper limits on the mechanical power are log\dot{E}_K~42.6-44.6 erg s^{-1}. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN cosmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyferts galaxies.

Measuring disease prevalence: a comparison of musculoskeletal disease using four general practice consultation databases.

Abstract: Background Primary care consultation data are an important source of information on morbidity prevalence. It is not known how reliable such figures are. Aim To compare annual consultation prevalence estimates for musculoskeletal conditions derived from four general practice consultation databases. Design of study Retrospective study of general practice consultation records. Setting Three national general practice consultation databases: i) Fourth Morbidity Statistics from General Practice (MSGP4, 1991/92), ii) Royal College of General Practitioners Weekly Returns Service (RCGP WRS, 2001), and iii) General Practice Research Database (GPRD, 1991 and 2001); and one regional database (Consultations in Primary Care Archive, 2001). Method Age-sex standardised persons consulting annual prevalence rates for musculoskeletal conditions overall, rheumatoid arthritis, osteoarthritis and arthralgia were derived for patients aged 15 years and over. Results GPRD prevalence of any musculoskeletal condition, rheumatoid arthritis and osteoarthritis was lower than that of the other databases. This is likely to be due to GPs not needing to record every consultation made for a chronic condition. MSGP4 gave the highest prevalence for osteoarthritis but low prevalence of arthralgia which reflects encouragement for GPs to use diagnostic rather than symptom codes. Conclusion Considerable variation exists in consultation prevalence estimates for musculoskeletal conditions. Researchers and health service planners should be aware that estimates of disease occurrence based on consultation will be influenced by choice of database. This is likely to be true for other chronic diseases and where alternative symptom labels exist for a disease. RCGP WRS may give the most reliable prevalence figures for musculoskeletal and other chronic diseases.

The anatomical basis for transcutaneous auricular vagus nerve stimulation.

Abstract: The array of end organ innervations of the vagus nerve, coupled with increased basic science evidence, has led to vagus nerve stimulation (VNS) being explored as a management option in a number of clinical disorders, such as heart failure, migraine and inflammatory bowel disease. Both invasive (surgically implanted) and non-invasive (transcutaneous) techniques of VNS exist. Transcutaneous VNS (tVNS) delivery systems rely on the cutaneous distribution of vagal afferents, either at the external ear (auricular branch of the vagus nerve) or at the neck (cervical branch of the vagus nerve), thus obviating the need for surgical implantation of a VNS delivery device and facilitating further investigations across a wide range of uses. The concept of electrically stimulating the auricular branch of the vagus nerve (ABVN), which provides somatosensory innervation to several aspects of the external ear, is relatively more recent compared with cervical VNS; thus, there is a relative paucity of literature surrounding its operation and functionality. Despite the increasing body of research exploring the therapeutic uses of auricular transcutaneous VNS (tVNS), a comprehensive review of the cutaneous, intracranial and central distribution of ABVN fibres has not been conducted to date. A review of the literature exploring the neuroanatomical basis of this neuromodulatory therapy is therefore timely. Our review article explores the neuroanatomy of the ABVN with reference to (1) clinical surveys examining Arnold's reflex, (2) cadaveric studies, (3) fMRI studies, (4) electrophysiological studies, (5) acupuncture studies, (6) retrograde tracing studies and (7) studies measuring changes in autonomic (cardiovascular) parameters in response to auricular tVNS. We also provide an overview of the fibre composition of the ABVN and the effects of auricular tVNS on the central nervous system. Cadaveric studies, of which a limited number exist in the literature, would be the 'gold-standard' approach to studying the cutaneous map of the ABVN; thus, there is a need for more such studies to be conducted. Functional magnetic resonance imaging (fMRI) represents a useful surrogate modality for discerning the auricular sites most likely innervated by the ABVN and the most promising locations for auricular tVNS. However, given the heterogeneity in the results of such investigations and the various limitations of using fMRI, the current literature lacks a clear consensus on the auricular sites that are most densely innervated by the ABVN and whether the brain regions secondarily activated by electrical auricular tVNS depend on specific parameters. At present, it is reasonable to surmise that the concha and inner tragus are suitable locations for vagal modulation. Given the therapeutic potential of auricular tVNS, there remains a need for the cutaneous map of the ABVN to be further refined and the effects of various stimulation parameters and stimulation sites to be determined.

Spin-glass behavior in a fine particle system

Abstract: A study of the magnetic behavior characteristic of a spin-glass, which has been examined for systems of ultrafine particles, is reported. The results obtained support the suggestion of E. P. Wohlfarth (1977) that spin-glass effects could arise from the clustering of impurity spins in the host material into ferromagnetic rich clusters. All the results are explained on the basis of the Neel superparamagnetic (blocking) model. The results obtained show that the behavior of fine particle systems is similar to that of certain spin-glass alloys (e.g., Au/Fe alloys). This result supports the idea that spin-glass alloys can be interpreted on the basis of a blocking model. >