4,632 research outputs found
Delay in diabetic retinopathy screening increases the rate of detection of referable diabetic retinopathy
Aims - To assess whether there is a relationship between delay in retinopathy screening after diagnosis of Type 2 diabetes and level of retinopathy detected.
Methods - Patients were referred from 88 primary care practices to an English National Health Service diabetic eye screening programme. Data for screened patients were extracted from the primary care databases using semi-automated data collection algorithms supplemented by validation processes. The programme uses two-field mydriatic digital photographs graded by a quality assured team.
Results - Data were available for 8183 screened patients with diabetes newly diagnosed in 2005, 2006 or 2007. Only 163 with Type 1 diabetes were identified and were insufficient for analysis. Data were available for 8020 with newly diagnosed Type 2 diabetes. Of these, 3569 were screened within 6 months, 2361 between 6 and 11 months, 1058 between 12 and 17 months, 366 between 18 and 23 months, 428 between 24 and 35 months, and 238 at 3 years or more after diagnosis. There were 5416 (67.5%) graded with no retinopathy, 1629 (20.3%) with background retinopathy in one eye, 753 (9.4%) with background retinopathy in both eyes and 222 (2.8%) had referable diabetic retinopathy. There was a significant trend (P = 0.0004) relating time from diagnosis to screening detecting worsening retinopathy. Of those screened within 6 months of diagnosis, 2.3% had referable retinopathy and, 3 years or more after diagnosis, 4.2% had referable retinopathy.
Conclusions - The rate of detection of referable diabetic retinopathy is elevated in those who were not screened promptly after diagnosis of Type 2 diabetes
Antigenic and genetic evolution of contemporary swine H1 influenza viruses in the United States
Several lineages of influenza A viruses (IAV) currently circulate in North American pigs. Genetic diversity is further increased by transmission of IAV between swine and humans and subsequent evolution. Here, we characterized the genetic and antigenic evolution of contemporary swine H1N1 and H1N2 viruses representing clusters H1-ι (1A.1), H1-β (1A.2), H1pdm (1A.3.3.2), H1-γ (1A.3.3.3), H1-δ1 (1B.2.2), and H1-δ2 (1B.2.1) currently circulating in pigs in the United States. The δ1-viruses diversified into two new genetic clades, H1-δ1a (1B.2.2.1) and H1-δ1b (1B.2.2.2), which were also antigenically distinct from the earlier H1-δ1-viruses. Further characterization revealed that a few key amino acid changes were associated with antigenic divergence in these groups. The continued genetic and antigenic evolution of contemporary H1 viruses might lead to loss of vaccine cross-protection that could lead to significant economic impact to the swine industry, and represents a challenge to public health initiatives that attempt to minimize swine-to-human IAV transmission
Photonic band mixing in linear chains of optically coupled micro-spheres
The paper deals with optical excitations arising in a one-dimensional chain
of identical spheres due optical coupling of whispering gallery modes (WGM).
The band structure of these excitations depends significantly on the
inter-mixing between WGMs characterized by different values of angular quantum
number, . We develop a general theory of the photonic band structure of
these excitations taking these effects into account and applied it to several
cases of recent experimental interest. In the case of bands originating from
WQMs with the angular quantum number of the same parity, the calculated
dispersion laws are in good qualitative agreement with recent experiment
results. Bands resulting from hybridization of excitations resulting from
whispering gallery modes with different parity of exhibits anomalous
dispersion properties characterized by a gap in the allowed values of
\emph{wave numbers} and divergence of group velocity.Comment: RevTex, 28 pages, 7 Figure
Microscopic dynamics of thin hard rods
Based on the collision rules for hard needles we derive a hydrodynamic
equation that determines the coupled translational and rotational dynamics of a
tagged thin rod in an ensemble of identical rods. Specifically, based on a
Pseudo-Liouville operator for binary collisions between rods, the Mori-Zwanzig
projection formalism is used to derive a continued fraction representation for
the correlation function of the tagged particle's density, specifying its
position and orientation. Truncation of the continued fraction gives rise to a
generalised Enskog equation, which can be compared to the phenomenological
Perrin equation for anisotropic diffusion. Only for sufficiently large density
do we observe anisotropic diffusion, as indicated by an anisotropic mean square
displacement, growing linearly with time. For lower densities, the Perrin
equation is shown to be an insufficient hydrodynamic description for hard
needles interacting via binary collisions. We compare our results to
simulations and find excellent quantitative agreement for low densities and
qualtitative agreement for higher densities.Comment: 21 pages, 6 figures, v2: clarifications and improved readabilit
Detecting non-Markovian plasmonic band gaps in quantum dots using electron transport
Placing a quantum dot close to a metal nanowire leads to drastic changes in
its radiative decay behavior because of evanescent couplings to surface
plasmons. We show how two non-Markovian effects, band-edge and retardation,
could be observed in such a system. Combined with a quantum dot p-i-n junction,
these effects could be readout via current-noise measurements. We also discuss
how these effects can occur in similar systems with restricted geometries, like
phononic cavities and photonic crystal waveguides. This work links two
previously separate topics: surface-plasmons and current-noise measurements.Comment: 8 page
Force on a neutral atom near conducting microstructures
We derive the non-retarded energy shift of a neutral atom for two different
geometries. For an atom close to a cylindrical wire we find an integral
representation for the energy shift, give asymptotic expressions, and
interpolate numerically. For an atom close to a semi-infinite halfplane we
determine the exact Green's function of the Laplace equation and use it derive
the exact energy shift for an arbitrary position of the atom. These results can
be used to estimate the energy shift of an atom close to etched microstructures
that protrude from substrates.Comment: 7 pages, 5 figure
Quantum Optics with Surface Plasmons
We describe a technique that enables strong, coherent coupling between
individual optical emitters and guided plasmon excitations in conducting
nano-structures at optical frequencies. We show that under realistic
conditions, optical emission can be almost entirely directed into the plasmon
modes. As an example, we describe an application of this technique involving
efficient generation of single photons on demand, in which the plasmon is
efficiently out-coupled to a dielectric waveguide.Comment: 11 pages, 3 figure
Can a charged ring levitate a neutral, polarizable object? Can Earnshaw's Theorem be extended to such objects?
Stable electrostatic levitation and trapping of a neutral, polarizable object
by a charged ring is shown to be theoretically impossible. Earnshaw's Theorem
precludes the existence of such a stable, neutral particle trap.Comment: 11 pages, 1 figur
The Incredible Years Autism Spectrum and Language Delays Parent program: A pragmatic, feasibility randomized controlled trial
Behavior problems in children with autism spectrum disorders (ASD) are common and particularly stressful for parents. This study aimed to examine the feasibility of delivering a parenting program in existing services, and the feasibility of conducting a future largeâscale Randomized Controlled Trial evaluation of the effectiveness of the intervention. Parents of children aged 3â8âyears with a diagnosis of ASD, or strongly suspected ASD were eligible to participate. A multicenter, pragmatic, feasibility randomized controlled trial was conducted in four specialist children's services in Wales. Families were randomly assigned to receive the Incredible YearsÂŽ Autism Spectrum and Language Delays (IYâASLD) parent program immediately or to a waitâlist, treatment as usual control condition. IYâASLD sessions were delivered once a week for 12âweeks. The primary outcomes related to feasibility (recruitment, retention, fidelity, and acceptability). Preliminary outcome analyses were conducted using covariance models controlling for study site and baseline scores. From October 5 to December 19, 2016, 58 families were randomized, 29 to IYâASLD and 29 to control. Three parents did not attend any sessions while 19 (73%) completed the program. Fidelity of delivery was high (88%), as was satisfaction with the program. Fiftyâthree (91%) completed the followâup measures. All 95% CIs for effect sizes included zero in exploratory outcome analyses. This study supports the feasibility of delivering the IYâASLD in existing services with good levels of acceptability and fidelity evident. A larger randomized controlled trial is required to examine the effectiveness of the program. Autism Res 2019. Š 2019 International Society for Autism Research, Wiley Periodicals, Inc
On the Possibility of Measuring the Abraham Force using Whispering Gallery Modes
Critical experimental tests of the time-dependent Abraham force in
phenomenological electrodynamics are scarce. In this paper we analyze the
possibility of making use of intensity-modulated whispering gallery modes in a
microresonator for this purpose. Systems of this kind appear attractive, as the
strong concentration of electromagnetic fields near the rim of the resonator
serves to enhance the Abraham torque exerted by the field. We analyze mainly
spherical resonators, although as an introductory step we consider also the
cylinder geometry. The order of magnitude of the Abraham torques are estimated
by inserting reasonable values for the various input parameters. As expected,
the predicted torques turn out to be very small, although probably not beyond
any reach experimentally. Our main idea is essentially a generalization of the
method used by G. B. Walker et al. [Can. J. Phys. 53, 2577] for low-frequency
fields, to the optical case.Comment: 6 pages, no figures. Minor typos corrected, acknowledgment added. To
appear in Phys. Rev.
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