24,490 research outputs found
"Sharp Elbows": Do the Middle-Classes have Advantages in Public Service Provision and if so how?
This paper summarises for a policy and practice audience the results of a review of the research evidence on middle class advantage in public services from the UK, US and Scandinavian countries published since 1980. The review was conducted by Annette Hastings from the University of Glasgow and Peter Matthews from Heriot-Watt University. Some sixty-five research papers were identified and subjected to systematic analysis in order to draw out key themes and evidence. The authors are grateful to the Arts and Humanities Research Council for funding this research and to a ‘virtual steering board' of policy practitioners for encouragement and guidance. All errors and omissions are the responsibility of the authors. A more detailed account of the research can be found by following links www.connectedcommunities.ac.uk
Localization and its consequences for quantum walk algorithms and quantum communication
The exponential speed-up of quantum walks on certain graphs, relative to
classical particles diffusing on the same graph, is a striking observation. It
has suggested the possibility of new fast quantum algorithms. We point out here
that quantum mechanics can also lead, through the phenomenon of localization,
to exponential suppression of motion on these graphs (even in the absence of
decoherence). In fact, for physical embodiments of graphs, this will be the
generic behaviour. It also has implications for proposals for using spin
networks, including spin chains, as quantum communication channels.Comment: 4 pages, 1 eps figure. Updated references and cosmetic changes for v
Phosphoinositide-dependent protein kinase-1 (PDK1)-independent activation of the protein kinase C substrate, protein kinase D
Phosphoinoisitide dependent kinase l (PDK1) is proposed to phosphorylate a key threonine residue within the catalytic domain of the protein kinase C (PKC) superfamily that controls the stability and catalytic competence of these kinases. Hence, in PDK1-null embryonic stem cells intracellular levels of PKCalpha, PKCbeta1, PKCgamma, and PKCepsilon are strikingly reduced. Although PDK1-null cells have reduced endogenous PKC levels they are not completely devoid of PKCs and the integrity of downstream PKC effector pathways in the absence of PDK1 has not been determined. In the present report, the PDK1 requirement for controlling the phosphorylation and activity of a well characterised substrate for PKCs, the serine kinase protein kinase D, has been examined. The data show that in embryonic stem cells and thymocytes loss of PDK1 does not prevent PKC-mediated phosphorylation and activation of protein kinase D. These results reveal that loss of PDK1 does not functionally inactivate all PKC-mediated signal transduction
Mitigation of artifacts due to isolated acoustic heterogeneities in photoacoustic computed tomography using a variable data truncation-based reconstruction method
Photoacoustic computed tomography (PACT) is an emerging computed imaging
modality that exploits optical contrast and ultrasonic detection principles to
form images of the absorbed optical energy density within tissue. If the object
possesses spatially variant acoustic properties that are unaccounted for by the
reconstruction method, the estimated image can contain distortions. While
reconstruction methods have recently been developed to compensate for this
effect, they generally require the object's acoustic properties to be known a
priori. To circumvent the need for detailed information regarding an object's
acoustic properties, we previously proposed a half-time reconstruction method
for PACT. A half-time reconstruction method estimates the PACT image from a
data set that has been temporally truncated to exclude the data components that
have been strongly aberrated. However, this method can be improved upon when
the approximate sizes and locations of isolated heterogeneous structures, such
as bones or gas pockets, are known. To address this, we investigate PACT
reconstruction methods that are based on a variable data truncation (VDT)
approach. The VDT approach represents a generalization of the half-time
approach, in which the degree of temporal truncation for each measurement is
determined by the distance between the corresponding ultrasonic transducer
location and the nearest known bone or gas void location. Computer-simulated
and experimental data are employed to demonstrate the effectiveness of the
approach in mitigating artifacts due to acoustic heterogeneities
Diagnosis of Helicobacter pylori by carbon-13 urea breath test using a portable mass spectrometer
CONTEXT: In the non-invasive detection of markers of disease, mass spectrometry is able to detect small quantities of volatile markers in exhaled air. However, the problem of size, expense and immobility of conventional mass spectrometry equipment has restricted its use. Now, a smaller, less expensive, portable quadrupole mass spectrometer system has been developed. Helicobacter pylori has been implicated in the development of chronic gastritis, gastric and duodenal ulcers and gastric cancer. OBJECTIVES: To compare the results obtained from the presence of H. pylori by a carbon-13 urea test using a portable quadrupole mass spectrometer system with those from a fixed mass spectrometer in a hospital-based clinical trial. METHODS: Following ethical approval, 45 patients attending a gastroenterology clinic at the Royal Liverpool University Hospital exhaled a breath sample into a Tedlar gas sampling bag. They then drank an orange juice containing urea radiolabelled with carbon and 30 min later gave a second breath sample. The carbon-13 content of both samples was measured using both quadrupole mass spectrometer systems. If the post-drink level exceeded the pre-drink level by 3% or more, a positive diagnosis for the presence of H. pylori was made. RESULTS: The findings were compared to the results using conventional isotope ratio mass spectrometry using a laboratory-based magnetic sector instrument off-site. The results showed agreement in 39 of the 45 patients. CONCLUSIONS: This study suggests that a portable quadrupole mass spectrometer is a potential alternative to the conventional centralised testing equipment. Future development of the portable quadrupole mass spectrometer to reduce further its size and cost is indicated, together with further work to validate this new equipment and to enhance its use in mass spectrometry diagnosis of other medical conditions
Magnetic Field Structure around Low-Mass Class 0 Protostars: B335, L1527 and IC348-SMM2
We report new 350 micron polarization observations of the thermal dust
emission from the cores surrounding the low-mass, Class 0 YSOs L1527,
IC348-SMM2 and B335. We have inferred magnetic field directions from these
observations, and have used them together with results in the literature to
determine whether magnetically regulated core-collapse and star-formation
models are consistent with the observations. These models predict a pseudo-disk
with its symmetry axis aligned with the core magnetic field. The models also
predict a magnetic field pinch structure on a scale less than or comparable to
the infall radii for these sources. In addition, if the core magnetic field
aligns (or nearly aligns) the core rotation axis with the magnetic field before
core collapse, then the models predict the alignment (or near alignment) of the
overall pinch field structure with the bipolar outflows in these sources. We
show that if one includes the distorting effects of bipolar outflows on
magnetic fields, then in general the observational results for L1527 and
IC348-SMM2 are consistent with these magnetically regulated models. We can say
the same for B335 only if we assume the distorting effects of the bipolar
outflow on the magnetic fields within the B335 core are much greater than for
L1527 and IC348-SMM2. We show that the energy densities of the outflows in all
three sources are large enough to distort the magnetic fields predicted by
magnetically regulated models.Comment: Accepted for publication in The Astrophysical Journa
High temperature onset of field-induced transitions in the spin-ice compound Dy2Ti2O7
We have studied the field-dependent ac magnetic susceptibility of single
crystals of Dy2Ti2O7 spin ice along the [111] direction in the temperature
range 1.8 K - 7 K. Our data reflect the onset of local spin ice order in the
appearance of different field regimes. In particular, we observe a prominent
feature at approximately 1.0 T that is a precursor of the low-temperature
metamagnetic transition out of field-induced kagome ice, below which the
kinetic constraints imposed by the ice rules manifest themselves in a
substantial frequency-dependence of the susceptibility. Despite the relatively
high temperatures, our results are consistent with a monopole picture, and they
demonstrate that such a picture can give physical insight to the spin ice
systems even outside the low-temperature, low-density limit where monopole
excitations are well-defined quasiparticles
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