37,533 research outputs found
Partnership research with older people: moving towards making the rhetoric a reality
As nursing develops closer partnerships with older people in delivering care, it also needs to develop partnerships in order to create the knowledge base for practice in a way that challenges professional hegemony and empowers older people. However, the process of developing partnerships in research takes place against a background of academic research traditions and norms, which can present obstacles to collaboration. This paper is a reflection on the issues that have arisen in three projects where older people were involved in research at different levels, from sources of data to independent researchers. It points to some of the areas that need further exploration and development
On the optical properties of carbon nanotubes--Part I. A general formula for the dynamical optical conductivity
This paper is the first one of a series of two articles in which we revisit
the optical properties of single-walled carbon nanotubes (SWNT). Produced by
rolling up a graphene sheet, SWNT owe their intriguing properties to their
cylindrical quasi-one-dimensional (quasi-1D) structure (the ratio length/radius
is experimentally of order of 10^3). We model SWNT by circular cylinders of
small diameters on the surface of which the conduction electron gas is confined
by the electric field generated by the fixed carbon ions. The pair-interaction
potential considered is the 3D Coulomb potential restricted to the cylinder. To
reflect the quasi-1D structure, we introduce a 1D effective many-body
Hamiltonian which is the starting-point of our analysis. To investigate the
optical properties, we consider a perturbation by a uniform time-dependent
electric field modeling an incident light beam along the longitudinal
direction. By using Kubo's method, we derive within the linear response theory
an asymptotic expansion in the low-temperature regime for the dynamical optical
conductivity at fixed density of particles. The leading term only involves the
eigenvalues and associated eigenfunctions of the (unperturbed) 1D effective
many-body Hamiltonian, and allows us to account for the sharp peaks observed in
the optical absorption spectrum of SWNT.Comment: Comments: 24 pages. Revised version. Accepted for publication in
J.M.
Device induces lungs to maintain known constant pressure
This device requires the use of thoracic muscles to maintain prescribed air pressure in the lungs for brief periods. It consists of a clear plastic hollow cylinder fitted with a mouthpiece, a spring-loaded piston, and a small vent for escaping air when exhalation into the mouthpiece displaces the piston
Perturbation Theory of Schr\"odinger Operators in Infinitely Many Coupling Parameters
In this paper we study the behavior of Hamilton operators and their spectra
which depend on infinitely many coupling parameters or, more generally,
parameters taking values in some Banach space. One of the physical models which
motivate this framework is a quantum particle moving in a more or less
disordered medium. One may however also envisage other scenarios where
operators are allowed to depend on interaction terms in a manner we are going
to discuss below. The central idea is to vary the occurring infinitely many
perturbing potentials independently. As a side aspect this then leads naturally
to the analysis of a couple of interesting questions of a more or less purely
mathematical flavor which belong to the field of infinite dimensional
holomorphy or holomorphy in Banach spaces. In this general setting we study in
particular the stability of selfadjointness of the operators under discussion
and the analyticity of eigenvalues under the condition that the perturbing
potentials belong to certain classes.Comment: 25 pages, Late
Pseudo-Hermitian Quantum Mechanics with Unbounded Metric Operators
We extend the formulation of pseudo-Hermitian quantum mechanics to
eta-pseudo-Hermitian Hamiltonian operators H with an unbounded metric operator
eta. In particular, we give the details of the construction of the physical
Hilbert space, observables, and equivalent Hermitian Hamiltonian for the case
that H has a real and discrete spectrum and its eigenvectors belong to the
domain of eta and consequently its positive square root.Comment: 8 pages, accepted for publication in Phil. Trans. R. Soc.
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
Self-adjointness of Dirac operators via Hardy-Dirac inequalities
Distinguished selfadjoint extensions of Dirac operators are constructed for a
class of potentials including Coulombic ones up to the critical case,
. The method uses Hardy-Dirac inequalities and quadratic form
techniques.Comment: PACS 03.65.P, 03.3
Quantum graphs with singular two-particle interactions
We construct quantum models of two particles on a compact metric graph with
singular two-particle interactions. The Hamiltonians are self-adjoint
realisations of Laplacians acting on functions defined on pairs of edges in
such a way that the interaction is provided by boundary conditions. In order to
find such Hamiltonians closed and semi-bounded quadratic forms are constructed,
from which the associated self-adjoint operators are extracted. We provide a
general characterisation of such operators and, furthermore, produce certain
classes of examples. We then consider identical particles and project to the
bosonic and fermionic subspaces. Finally, we show that the operators possess
purely discrete spectra and that the eigenvalues are distributed following an
appropriate Weyl asymptotic law
Instrument for use in performing a controlled Valsalva maneuver Patent
Piston device for producing known constant positive pressure within lungs by using thoracic muscle
- âŠ