527 research outputs found
Bandwidth of linearized electrooptic modulators
Many schemes have been proposed to make high dynamic range analog radio frequency (RF) photonic links by linearizing the transfer function of the link's modulator. This paper studies the degrading effects of finite transit time and optical and electrical velocity dispersion on such linearization schemes. It further demonstrates that much of the lost dynamic range in some modulators may be regained by segmenting and rephasing the RF transmission line
Effects of Velocity Mismatch and Transit Time on Linearized Electro-Optic Modulators
The program written for this study allows calculations for periodically-rephased modulators since the modulator is already broken up into a series of incremental matrices. Thus if the modulator is allowed to be mismatched for a few matrices and then rephased for the next few and so on, we have the results shown for a four segment modulator (3 rephasings). modulators are considered
Subconjunctival delivery of p75NTR antagonists reduces the inflammatory, vascular, and neurodegenerative pathologies of diabetic retinopathy
The p75NTR is a novel therapeutic target validated in a streptozotocin mouse model of diabetic retinopathy. Intravitreal (IVT) injection of small molecule p75NTR antagonist THX-B was therapeutic and resolved the inflammatory, vascular, and neurodegenerative phases of the retinal pathology. To simplify clinical translation, we sought a superior drug delivery method that circumvents risks associated with IVT injections. METHODS. We compared the pharmacokinetics of a single 40 lg subconjunctival (SCJ) depot to the reported effective 5 lg IVT injections of THX-B. We quantified therapeutic efficacy, with endpoints of inflammation, edema, and neuronal death. RESULTS. The subconjunctival depot affords retinal exposure equal to IVT injection, without resulting in detectable drug in circulation. At week 2 of diabetic retinopathy, the SCJ depot provided therapeutic efficacy similar to IVT injections, with reduced inflammation, reduced edema, reduced neuronal death, and a long-lasting protection of the retinal structure. CONCLUSIONS. Subconjunctival injections are a safe and effective route for retinal delivery of p75NTR antagonists. The subconjunctival route offers an advantageous, less-invasive, more compliant, and nonsystemic method to deliver p75NTR antagonists for the treatment of retinal diseases.Fil: Galan, Alba. Mc Gill University. Lady Davis Research Intitute; CanadáFil: Barcelona, Pablo Federico. Mc Gill University. Lady Davis Research Intitute; Canadá. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico CĂłrdoba. Centro de Investigaciones en BioquĂmica ClĂnica e InmunologĂa; ArgentinaFil: Nedev, Hinyu. Mc Gill University. Lady Davis Research Intitute; CanadáFil: Sarunic, Marinko V.. University Fraser Simon; CanadáFil: Jian, Yifan. University Fraser Simon; CanadáFil: Saragovi, H. Uri. Mc Gill University. Lady Davis Research Intitute; Canad
Bathymetric terrain model of the Atlantic margin for marine geological investigations.
Bathymetric terrain models of seafloor morphology are an important component of marine geological investigations. Advances in acquisition and processing technologies of bathymetric data have facilitated the creation of high-resolution bathymetric surfaces that approach the resolution of similar surfaces available for onshore investigations. These bathymetric terrain models provide a detailed representation of the Earth’s subaqueous surface and, when combined with other geophysical and geological datasets, allow for interpretation of modern and ancient geological processes. The purpose of the bathymetric terrain model presented in this report is to provide a high-quality bathymetric surface of the Atlantic margin of the United States that can be used to augment current and future marine geological investigations. The input data for this bathymetric terrain model, covering almost 305,000 square kilometers, were acquired by several sources, including the U.S. Geological Survey, the National Oceanic and Atmospheric Administration National Geophysical Data Center and the Ocean Exploration Program, the University of New Hampshire, and the Woods Hole Oceanographic Institution. These data have been edited using hydrographic data processing software to maximize the quality, usability, and cartographic presentation of the combined terrain model
Inclusive production in a QCD and N=4 SYM motivated model for soft interactions
The results presented in this paper differ from our previous unsuccessful
attempt to predict the rapidity distribution at . The original
version of our model (GLMM) only summed a particular class of Pomeron diagrams
(enhanced diagrams). We believe that this was the reason for our failure to
describe the inclusive LHC data. We have developed a new approach
(GLM) that also includes the summation of the semi-enhanced diagrams.This
contribution is essential for a successful description of the inclusive
distributions, which is presented here.Comment: 4 pages, 3 figure
Similarity classes of 3x3 matrices over a local principal ideal ring
In this paper similarity classes of three by three matrices over a local
principal ideal commutative ring are analyzed. When the residue field is
finite, a generating function for the number of similarity classes for all
finite quotients of the ring is computed explicitly.Comment: 14 pages, final version, to appear in Communications in Algebr
Selection Rules for Black-Hole Quantum Transitions
We suggest that quantum transitions of black holes comply with selection
rules, analogous to those of atomic spectroscopy. In order to identify such
rules, we apply Bohr's correspondence principle to the quasinormal ringing
frequencies of black holes. In this context, classical ringing frequencies with
an asymptotically vanishing real part \omega_R correspond to virtual quanta,
and may thus be interpreted as forbidden quantum transitions. With this
motivation, we calculate the quasinormal spectrum of neutrino fields in
spherically symmetric black-hole spacetimes. It is shown that \omega_R->0 for
these resonances, suggesting that the corresponding fermionic transitions are
quantum mechanically forbidden.Comment: 4 pages, 2 figure
Asymptotic Spectroscopy of Rotating Black Holes
We calculate analytically the transmission and reflection amplitudes for
waves incident on a rotating black hole in d=4, analytically continued to
asymptotically large, nearly imaginary frequency. These amplitudes determine
the asymptotic resonant frequencies of the black hole, including quasinormal
modes, total-transmission modes and total-reflection modes. We identify these
modes with semiclassical bound states of a one-dimensional Schrodinger
equation, localized along contours in the complexified r-plane which connect
turning points of corresponding null geodesics. Each family of modes has a
characteristic temperature and chemical potential. The relations between them
provide hints about the microscopic description of the black hole in this
asymptotic regime.Comment: References adde
Traversal time for electron tunneling in water
The traversal time for tunneling is a measure of the time during which the
transmitted particle can be affected by interactions localized in the barrier.
The Buttiker-Landauer approach, which estimates this time by imposing an
internal clock on the system, has been applied so far for relatively simple
1-dimensional models. Here we apply this approach to estimate the traversal
time for electron tunneling through a realistic 3-dimensional model of a water
layer. Observed structure in the energy dependence of times computed reflects
the existence of transient tunneling resonances associated with instantaneous
water structures.Comment: 9 pages, 3 figures. Submitted to the Journal of Chemical Physic
Linearized modulators for analog photonic links
The potential applications of high dynamic range analog RF photonic links include antenna remoting, photonic-coupled phased-array antennas, and cable-television transmission. This paper compares the results obtained with a number of different electro-optic modulator types and link configurations assuming an ideal velocity-matched modulator. The degrading effects of velocity mismatching are also presented for some of the modulators studied
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