2,367 research outputs found
Contact-mediated control of radial migration of corneal epithelial cells
We thank Darrin Sheppard and other staff at the University of Aberdeen Medical Research Facility for specialist technical assistance. We thank Patsy D. Goast for overnight microscope monitoring. This work was performed under the Biotechnology and Bioscience Research Council Grant number BB/E015840/1 to JMC.Peer reviewedPublisher PD
Pressure ulcer related pain in community populations: a prevalence survey.
BACKGROUND: Pressure ulcers are costly to the healthcare provider and can have a major impact on patient's quality of life. One of the most distressing symptoms reported is pain. There is very little published data on the prevalence and details of pain experienced by patients with pressure ulcers, particularly in community populations. The study was conducted in two community NHS sites in the North of England. METHODS: The aim was to estimate the prevalence of pressure area related pain within a community population. We also explored the type and severity of the pain and its association with pressure ulcer classification. A cross-sectional survey was performed of community nurses caseloads to identify adult patients with pressure ulcers and associated pain. Consenting patients then had a full pain assessment and verification of pressure ulcer grade. RESULTS: A total of 287 patients were identified with pressure ulcers (0.51 per 1000 adult population). Of the 176 patients who were asked, 133 (75.6%) reported pain. 37 patients consented to a detailed pain assessment. Painful pressure ulcers of all grades and on nearly all body sites were identified. Pain intensity was not related to number or severity of pressure ulcer. Both inflammatory and neuropathic pain were reported at all body sites however the proportion of neuropathic pain was greater in pressure ulcers on lower limbs. CONCLUSIONS: This study has identified the extent and type of pain suffered by community patients with pressure ulcers and indicates the need for systematic and regular pain assessment and treatment
Active current sheets and hot flow anomalies in Mercury's bow shock
Hot flow anomalies (HFAs) represent a subset of solar wind discontinuities
interacting with collisionless bow shocks. They are typically formed when the
normal component of motional (convective) electric field points toward the
embedded current sheet on at least one of its sides. The core region of an HFA
contains hot and highly deflected ion flows and rather low and turbulent
magnetic field. In this paper, we report first observations of HFA-like events
at Mercury identified over a course of two planetary years. Using data from the
orbital phase of the MErcury Surface, Space ENvironment, GEochemistry, and
Ranging (MESSENGER) mission, we identify a representative ensemble of active
current sheets magnetically connected to Mercury's bow shock. We show that some
of these events exhibit unambiguous magnetic and particle signatures of HFAs
similar to those observed earlier at other planets, and present their key
physical characteristics. Our analysis suggests that Mercury's bow shock does
not only mediate the flow of supersonic solar wind plasma but also provides
conditions for local particle acceleration and heating as predicted by previous
numerical simulations. Together with earlier observations of HFA activity at
Earth, Venus and Saturn, our results confirm that hot flow anomalies are a
common property of planetary bow shocks, and show that the characteristic size
of these events is of the order of one planetary radius.Comment: 39 pages, 15 figures, 2 table
The Embedding of Schwarzschild in Braneworld
The braneworlds models were inspired partly by Kaluza-Klein's theory, where
both the gravitational and the gauge fields are obtained from the geometry of a
higher dimensional space. The positive aspects of these models consist in
perspectives of modifications it could bring in to particle physics, such as:
unification in a TeV scale, quantum gravity in this scale and deviation of
Newton's law for small distances. One of the principles of these models is to
suppose that all space-times can be embedded in a bulk of higher dimension. The
main result in these notes is a theorem showing a mathematical inconsistency of
the Randall-Sundrum braneworld model, namely that the Schwarzschild space-time
cannot be embedded locally and isometrically in a five dimensional bulk with
constant curvature,(for example AdS-5). From the point of view of
semi-Riemannian geometry this last result represents a serious restriction to
the Randall-Sundrum's braneworld model.Comment: Published in the Int. J. Theor. Phys, 200
Feminist phenomenology and the woman in the running body
Modern phenomenology, with its roots in Husserlian philosophy, has been taken up and utilised in a myriad of ways within different disciplines, but until recently has remained relatively under-used within sports studies. A corpus of sociological-phenomenological work is now beginning to develop in this domain, alongside a longer standing literature in feminist phenomenology. These specific social-phenomenological forms explore the situatedness of lived-body experience within a particular social structure. After providing a brief overview of key strands of phenomenology, this article considers some of the ways in which sociological, and particularly feminist phenomenology, might be used to analyse female sporting embodiment. For illustrative purposes, data from an autophenomenographic project on female distance running are also included, in order briefly to demonstrate the application of phenomenology within sociology, as both theoretical framework and methodological approach
Petrov types of slowly rotating fluid balls
Circularly rotating axisymmetric perfect fluid space-times are investigated
to second order in the small angular velocity. The conditions of various
special Petrov types are solved in a comoving tetrad formalism. A number of
theorems are stated on the possible Petrov types of various fluid models. It is
shown that Petrov type II solutions must reduce to the de Sitter spacetime in
the static limit. Two space-times with a physically satisfactory
energy-momentum tensor are investigated in detail. For the rotating
incompressible fluid, it is proven that the Petrov type cannot be D. The
equation of the rotation function can be solved for the Tolman type
IV fluid in terms of quadratures. It is also shown that the rotating version of
the Tolman IV space-time cannot be Petrov type D.Comment: 14 pages, version to appear in Gen. Rel. Gra
Requirement of Pax6 for the integration of guidance cues in cell migration
The intricate patterns of cell migration that are found throughout development are generated through a vast array of guidance cues. Responding integratively to distinct, often conflicting, migratory signals is probably crucial for cells to reach their correct destination. Pax6 is a master transcription factor with key roles in neural development that include the control of cell migration. In this study, we have investigated the ability of cells derived from cortical neurospheres from wildtype (WT) and Pax6-/- mouse embryos to integrate diverging guidance cues. We used two different cues, either separately or in combination: substratum nanogrooves to induce contact guidance, and electric fields (EFs) to induce electrotaxis. In the absence of an EF, both WT and Pax6-/- cells aligned and migrated parallel to grooves, and on a flat substrate both showed marked electrotaxis towards the cathode. When an EF was applied in a perpendicular orientation to grooves, WT cells responded significantly to both cues, migrating in highly oblique trajectories in the general direction of the cathode. However, Pax6-/- cells had an impaired response to both cues simultaneously. Our results demonstrate that these neurosphere derived cells have the capacity to integrate diverging guidance cues, which requires Pax6 function
Potentiometric Biosensing of Ascorbic Acid, Uric Acid, and Cysteine in Microliter Volumes Using Miniaturized Nanoporous Gold Electrodes
Potentiometric redox sensing is a relatively inexpensive and passive approach to evaluate the overall redox state of complex biological and environmental solutions. The ability to make such measurements in ultra-small volumes using high surface area, nanoporous electrodes is of particular importance as such electrodes can improve the rates of electron transfer and reduce the effects of biofouling on the electrochemical signal. This work focuses on the fabrication of miniaturized nanoporous gold (NPG) electrodes with a high surface area and a small footprint for the potentiometric redox sensing of three biologically relevant redox molecules (ascorbic acid, uric acid, and cysteine) in microliter volumes. The NPG electrodes were inexpensively made by attaching a nanoporous gold leaf prepared by dealloying 12K gold in nitric acid to a modified glass capillary (1.5 mm id) and establishing an electrode connection with copper tape. The surface area of the electrodes was ~1.5 cm2, providing a roughness factor of ~16 relative to the geometric area of 0.09 cm2. Scanning electron microscopy confirmed the nanoporous framework. A linear dependence between the open-circuit potential (OCP) and the logarithm of concentration (e.g., Nernstian-like behavior) was obtained for all three redox molecules in 100 μL buffered solutions. As a first step towards understanding a real system, the response associated with changing the concentration of one redox species in the presence of the other two was examined. These results show that at NPG, the redox potential of a solution containing biologically relevant concentrations of ascorbic acid, uric acid, and cysteine is strongly influenced by ascorbic acid. Such information is important for the measurement of redox potentials in complex biological solutions
On the structure of the new electromagnetic conservation laws
New electromagnetic conservation laws have recently been proposed: in the
absence of electromagnetic currents, the trace of the Chevreton superenergy
tensor, is divergence-free in four-dimensional (a) Einstein spacetimes
for test fields, (b) Einstein-Maxwell spacetimes. Subsequently it has been
pointed out, in analogy with flat spaces, that for Einstein spacetimes the
trace of the Chevreton superenergy tensor can be rearranged in the
form of a generalised wave operator acting on the energy momentum
tensor of the test fields, i.e., . In this
letter we show, for Einstein-Maxwell spacetimes in the full non-linear theory,
that, although, the trace of the Chevreton superenergy tensor can
again be rearranged in the form of a generalised wave operator
acting on the electromagnetic energy momentum tensor, in this case the result
is also crucially dependent on Einstein's equations; hence we argue that the
divergence-free property of the tensor has
significant independent content beyond that of the divergence-free property of
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