398 research outputs found
Ranibizumab for idiopathic epiretinal membranes: A retrospective case series
AbstractPurposeTo study the effect of intravitreal ranibizumab on idiopathic epiretinal membranes (ERMs).MethodsA retrospective cohort study on a consecutive series of ranibizumab intravitreal injections for epiretinal membranes was performed. Four cases were identified by reviewing a claims database linked to electronic medical records. All patients received a total of three 0.05mg/0.05ml ranibizumab intravitreal injections at a monthly interval. The primary outcome measure was the final best-corrected visual acuity (BCVA) at the end of the injection series, and the final central macular thickness (CMT).ResultsAll four patients completed 3months follow-up after the last ranibizumab injection. The mean baseline CMT was 509microns (SD=111). A trend was noticed for reduction in CMT (Î=41microns) P=0.08. Three patients improved by one line in their BCVA. The remaining patient maintained the same BCVA. No complications were noted.ConclusionIn this study, intravitreal injection of ranibizumab marginally reduced retinal thickness in four patients with minimal improvement in visual acuity. No safety concerns were noticed. Further basic science and clinical studies may be warranted to assess the role of vascular endothelial growth factor and the effect of ranibizumab on idiopathic epiretinal membranes
A single-mask thermal displacement sensor in MEMS
Position sensing in MEMS is often based on the principle of varying capacitance [1]. Alternative position sensing principles include using integrated optical waveguides [2] or varying thermal conductance [3]. Lantz et al demonstrated a thermal displacement sensor achieving nanometre resolution on a 100mm range. However a multi-mask production process and manual assembly were needed to fabricate this displacement sensor. In this work we present a 1-DOF thermal displacement sensor integrated with an actuated stage, and its experimental characterization. The system was fabricated in the device layer of a silicon-on-\ud
insulator (SOI) wafer using a single-mask process.\ud
\u
Testing Physical and Mathematical Criteria in a New Meandering Autocorrelation Function
An alternative formulation for the low wind speed-meandering autocorrelation function is presented. Employing distinct theoretical criteria, this mathematical formulation, from a physical point of view, is validated. This expression for the meandering autocorrelation function reproduces well-observed wind-meandering data measured in a micrometeorological site located in a pampa ecosystem area (South Brazil). The comparison shows that the alternative relation for the meandering autocorrelation function is suitable to provide meandering characteristic parameters. Employing MacLaurinâs series expansion of a lateral dispersion parameter that represents cases in which turbulence and oscillatory movements associated to the meandering events coexist, a new formulation for the turbulence/meandering dissipation rate has been presented
A single-mask thermal displacement sensor in MEMS
This work presents a MEMS displacement sensor based on the conductive heat transfer of a resistively heated silicon structure towards an actuated stage parallel to the structure. This differential sensor can be easily incorporated into a silicon-on-insulator-based process, and fabricated within the same mask as electrostatic actuators and flexure-based stages. We discuss a lumped capacitance model to optimize the sensor sensitivity as a function of the doping concentration, the operating temperature, the heater length and width. We demonstrate various sensor designs. The typical sensor resolution is 2 nm within a bandwidth of 25 Hz at a full scale range of 110 ÎŒm
Induced Parity Nonconserving Interaction and Enhancement of Two-Nucleon Parity Nonconserving Forces
Two-nucleon parity nonconserving (PNC) interaction induced by the
single-particle PNC weak potential and the two-nucleon residual strong
interaction is considered. An approximate analytical formula for this Induced
PNC Interaction (IPNCI) between proton and neutron is derived (), and the
interaction constant is estimated. As a result of coherent contributions from
the nucleons to the PNC potential, IPNCI is an order of magnitude stronger
() than the residual weak two-nucleon interaction and has a
different coordinate and isotopic structure (e.g., the strongest part of IPNCI
does not contribute to the PNC mean field). IPNCI plays an important role in
the formation of PNC effects, e.g., in neutron-nucleus reactions. In that case,
it is a technical way to take into account the contribution of the distant
(small) components of a compound state which dominates the result. The absence
of such enhancement () in the case of T- and P-odd interaction
completes the picture.Comment: Phys. Rev. C, to appear; 17 pages, revtex 3, no figure
Prospects for asteroseismology
The observational basis for asteroseismology is being dramatically
strengthened, through more than two years of data from the CoRoT satellite, the
flood of data coming from the Kepler mission and, in the slightly longer term,
from dedicated ground-based facilities. Our ability to utilize these data
depends on further development of techniques for basic data analysis, as well
as on an improved understanding of the relation between the observed
frequencies and the underlying properties of the stars. Also, stellar modelling
must be further developed, to match the increasing diagnostic potential of the
data. Here we discuss some aspects of data interpretation and modelling,
focussing on the important case of stars with solar-like oscillations.Comment: Proc. HELAS Workshop on 'Synergies between solar and stellar
modelling', eds M. Marconi, D. Cardini & M. P. Di Mauro, Astrophys. Space
Sci., in the press Revision: correcting abscissa labels on Figs 1 and
Magnetic Reconnection in Extreme Astrophysical Environments
Magnetic reconnection is a basic plasma process of dramatic rearrangement of
magnetic topology, often leading to a violent release of magnetic energy. It is
important in magnetic fusion and in space and solar physics --- areas that have
so far provided the context for most of reconnection research. Importantly,
these environments consist just of electrons and ions and the dissipated energy
always stays with the plasma. In contrast, in this paper I introduce a new
direction of research, motivated by several important problems in high-energy
astrophysics --- reconnection in high energy density (HED) radiative plasmas,
where radiation pressure and radiative cooling become dominant factors in the
pressure and energy balance. I identify the key processes distinguishing HED
reconnection: special-relativistic effects; radiative effects (radiative
cooling, radiation pressure, and Compton resistivity); and, at the most extreme
end, QED effects, including pair creation. I then discuss the main
astrophysical applications --- situations with magnetar-strength fields
(exceeding the quantum critical field of about 4 x 10^13 G): giant SGR flares
and magnetically-powered central engines and jets of GRBs. Here, magnetic
energy density is so high that its dissipation heats the plasma to MeV
temperatures. Electron-positron pairs are then copiously produced, making the
reconnection layer highly collisional and dressing it in a thick pair coat that
traps radiation. The pressure is dominated by radiation and pairs. Yet,
radiation diffusion across the layer may be faster than the global Alfv\'en
transit time; then, radiative cooling governs the thermodynamics and
reconnection becomes a radiative transfer problem, greatly affected by the
ultra-strong magnetic field. This overall picture is very different from our
traditional picture of reconnection and thus represents a new frontier in
reconnection research.Comment: Accepted to Space Science Reviews (special issue on magnetic
reconnection). Article is based on an invited review talk at the
Yosemite-2010 Workshop on Magnetic Reconnection (Yosemite NP, CA, USA;
February 8-12, 2010). 30 pages, no figure
On the verge of Umdeutung in Minnesota: Van Vleck and the correspondence principle (Part One)
In October 1924, the Physical Review, a relatively minor journal at the time,
published a remarkable two-part paper by John H. Van Vleck, working in virtual
isolation at the University of Minnesota. Van Vleck combined advanced
techniques of classical mechanics with Bohr's correspondence principle and
Einstein's quantum theory of radiation to find quantum analogues of classical
expressions for the emission, absorption, and dispersion of radiation. For
modern readers Van Vleck's paper is much easier to follow than the famous paper
by Kramers and Heisenberg on dispersion theory, which covers similar terrain
and is widely credited to have led directly to Heisenberg's "Umdeutung" paper.
This makes Van Vleck's paper extremely valuable for the reconstruction of the
genesis of matrix mechanics. It also makes it tempting to ask why Van Vleck did
not take the next step and develop matrix mechanics himself.Comment: 82 page
Search for the glueball candidates f0(1500) and fJ(1710) in gamma gamma collisions
Data taken with the ALEPH detector at LEP1 have been used to search for gamma
gamma production of the glueball candidates f0(1500) and fJ(1710) via their
decay to pi+pi-. No signal is observed and upper limits to the product of gamma
gamma width and pi+pi- branching ratio of the f0(1500) and the fJ(1710) have
been measured to be Gamma_(gamma gamma -> f0(1500)). BR(f0(1500)->pi+pi-) <
0.31 keV and Gamma_(gamma gamma -> fJ(1710)). BR(fJ(1710)->pi+pi-) < 0.55 keV
at 95% confidence level.Comment: 10 pages, 3 figure
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