7,114 research outputs found
Axisymmetric flow of ideal fluid moving in a narrow domain: a study of the axisymmetric hydrostatic Euler equations
In this article we will introduce a new model to describe the leading order
behavior of an ideal and axisymmetric fluid moving in a very narrow domain.
After providing a formal derivation of the model, we will prove the
well-posedness and provide a rigorous mathematical justification for the formal
derivation under a new sign condition. Finally, a blowup result regarding this
model will be discussed as well.Comment: 33 page
What do we really know about infants who attend Accident and Emergency departments?
Aims: Accident and Emergency attendances continue to rise. Infants are disproportionately represented. This study examines the clinical reasons infants attend UK Accident and Emergency departments.
Methods: A retrospective review of 6,667 infants aged less than one year attending Accident and Emergency at two district general hospitals in London from 1st April 2009 to 30th March 2010. All infants had been assigned to a diagnostic category by the medical coding department according to National Health Service (NHS) data guidelines, based on the clinical diagnoses stated in the medical records. The Accident and Emergency case notes of a random subsample of 10% of infants in each of the top five recorded diagnostic categories (n = 535) were reviewed in detail and audited against the standard national NHS data set.
Results: The top 5 clinical diagnoses were âinfectious diseasesâ, âgastrointestinalâ, ârespiratoryâ, âunclassifiableâ and âno abnormality detectedâ (NAD). A third of infants were originally given a diagnosis of unclassifiable (21.5%) or NAD (11.5%). After detailed case-note review, we were able to reduce this to 9.7% (95% confidence interval (CI): 9.0, 10.4) and 8.8% (95% CI: 8.1, 9.5), respectively.
Conclusion: This study demonstrates the importance of providing a clear clinical diagnosis and coding system for Accident and Emergency attendances and understanding that system fully. This would allow for better informed health service evaluation, planning and research as each of these relies on the interpretation of routine health-care data. Furthermore, the relatively high proportion (10%) of infants attending with no discernible underlying medical abnormality suggests the health needs of a significant proportion of infants attending Accident and Emergency departments may be better addressed by alternative service provision and/or improved education and support to parents
Preparation of crosslinked 1,2,4-oxadiazole polymer
New crosslinked 1,2,4-oxadiazole elastomers were prepared by thermally condensing a monomer having the formula H2N(HON)C-R-Q, wherein Q is a triazine ring-forming group such as nitrile or amidine or a mixture of such group with amidoxime, or a mixture of said monomer with R C(NOH)NH2 sub 2 with R in these formulas standing for a bivalent organic radical. In the monomer charge, the overall proportions of amidoxime groups to triazine ring-forming groups varies depending on the extent of crosslinking desired in the final polymer
Insecurity of position-based quantum cryptography protocols against entanglement attacks
Recently, position-based quantum cryptography has been claimed to be
unconditionally secure. In contrary, here we show that the existing proposals
for position-based quantum cryptography are, in fact, insecure if entanglement
is shared among two adversaries. Specifically, we demonstrate how the
adversaries can incorporate ideas of quantum teleportation and quantum secret
sharing to compromise the security with certainty. The common flaw to all
current protocols is that the Pauli operators always map a codeword to a
codeword (up to an irrelevant overall phase). We propose a modified scheme
lacking this property in which the same cheating strategy used to undermine the
previous protocols can succeed with a rate at most 85%. We conjecture that the
modified protocol is unconditionally secure and prove this to be true when the
shared quantum resource between the adversaries is a two- or three- level
system
Physical transformations between quantum states
Given two sets of quantum states {A_1, ..., A_k} and {B_1, ..., B_k},
represented as sets of density matrices, necessary and sufficient conditions
are obtained for the existence of a physical transformation T, represented as a
trace-preserving completely positive map, such that T(A_i) = B_i for i = 1,
..., k. General completely positive maps without the trace-preserving
requirement, and unital completely positive maps transforming the states are
also considered
Optically controlled orbital angular momentum generation in a polaritonic quantum fluid
Applications of the orbital angular momentum (OAM) of light range from the
next generation of optical communication systems to optical imaging and optical
manipulation of particles. Here we propose a micron-sized semiconductor source
which emits light with pre-defined OAM components. This source is based on a
polaritonic quantum fluid. We show how in this system modulational
instabilities can be controlled and harnessed for the spontaneous formation of
OAM components not present in the pump laser source. Once created, the OAM
states exhibit exotic flow patterns in the quantum fluid, characterized by
generation-annihilation pairs. These can only occur in open systems, not in
equilibrium condensates, in contrast to well-established vortex-antivortex
pairs
Solar neutrino interactions: Using charged currents at SNO to tell neutral currents at Super-Kamiokande
In the presence of flavor oscillations, muon and tau neutrinos can contribute
to the Super-Kamiokande (SK) solar neutrino signal through the neutral current
process \nu_{\mu,\tau} e^{-}\to \nu_{\mu,\tau} e^{-}. We show how to separate
the \nu_e and \nu_{\mu,\tau} event rates in SK in a model independent way, by
using the rate of the charged current process \nu_e d \to p p e^{-} from the
Sudbury Neutrino Observatory (SNO) experiment, with an appropriate choice of
the SK and SNO energy thresholds. Under the additional hypothesis of no
oscillations into sterile states, we also show how to determine the absolute
^{8}B neutrino flux from the same data set, independently of the \nu_e survival
probability.Comment: 14 pages (RevTeX), incl. 3 figures (epsf), submitted to Phys. ReV.
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