605 research outputs found
Analyses of 100 Gbps Coherent System Performances
This paper presents the results of laboratory and field testing of coherent 100 Gbps system with DP-QPSK modulation. Several measurements were performed including power budget, nonlinear threshold, spectrum filtration, constellation diagram, interoperability with 10 Gbps lambdas and dispersion compensation type impact. Field tests addressed transmission of 100 Gbps signal as an Alien Wavelength through multivendor network, influence of photonic service parallel to 100 Gbps signal and performance of 100 Gbps system over single fiber bidirectional transmission lines. 100 Gbps system has been found extremely resilient to most classical impairments thanks to advances error coding and compatible with standard 10 Gbps NRZ lambdas and any type of dispersion compensation. The system was also working over single fiber bidirectional lines and in parallel with Photonic Service of time transfer. The paper also shows recent results of single hop test with 100 Gbps system in laboratory environment
Data Transparent and Polarization Insensitive All-Optical Switch based on Fibers with Enhanced Nonlinearity
We have developed a data transparent optical packet switch prototype employing wavelength conversion based on four-wave mixing. The switch is composed of an electro-optical control unit and an all-optical switching segment. To achieve higher switching efficiencies, Ge-doped silica suspended-core and chalcogenide arsenicselenide single-mode fibers were experimentally evaluated and compared to conventional highly-nonlinear fiber. Improved connectorization technology has been developed for Ge-doped suspended-core fiber, where we achieved connection losses of 0.9 dB. For the arsenic-selenide fiber we present a novel solid joint technology, with connection losses of only 0.25 dB, which is the lowest value presented up-to-date. Conversion efficiency of -13.7 dB was obtained for the highly-nonlinear fiber, which is in perfect correlation with previously published results and thus verifies the functionality of the prototype. Conversion efficiency of -16.1 dB was obtained with arsenic-selenide fiber length reduced to five meters within simulations, based on measurement results with a 26 m long component. Employment of such a short arsenic-selenide fiber segment allows significant broadening of the wavelength conversion spectral range due to possible neglection of dispersion
On Vector Bundles of Finite Order
We study growth of holomorphic vector bundles E over smooth affine manifolds.
We define Finsler metrics of finite order on E by estimates on the holomorphic
bisectional curvature. These estimates are very similar to the ones used by
Griffiths and Cornalba to define Hermitian metrics of finite order. We then
generalize the Vanishing Theorem of Griffiths and Cornalba to the Finsler
context. We develop a value distribution theory for holomorphic maps from the
projectivization of E to projective space. We show that the projectivization of
E can be immersed into a projective space of sufficiently large dimension via a
map of finite order.Comment: version 2 has some typos corrected; to appear in Manuscripta
Mathematic
Verhalten und Eisvolumen der Pasterze (Glocknergruppe) in Beziehung zu den klimatischen Bedingungen
Chronic Implantation of Intravascular Cardioverter Defibrillator in a Canine Model
INTRODUCTION: A percutaneously placed implantable intravascular defibrillator (PICD) has been developed with a right ventricular (RV) single-coil lead and titanium electrodes in the superior vena cava (SVC) and the inferior vena cava (IVC). This study evaluated implant techniques, device stability, and anchor histology of the PICD over 9 months in a canine model. METHODS: Twenty-four hounds (wt = 30-55 kg) were anesthetized and a custom sheath introduced into the right femoral vein. The PICD was advanced over a wire and positioned with the titanium electrodes (cathodes) in the SVC and the IVC. A nitinol anchor secured the device in the jugular. The RV lead was positioned in the RV apex and screwed into place. The catheters, wires, and sheath were removed with an average implant time of 14 minutes. In one group of animals (n = 13), serial venograms were performed at 7 days, 14 days, and 28 days. In a second group (n = 6) and third group (n = 5), venograms were also performed at 90 days and 270 days, respectively. Six canines were sacrificed and anchor histologic examination done at 90 days. RESULTS: All implants were successful with no surgical complications observed. Devices (N = 24) remained appropriately positioned with no anchor migration. Histology at 90 days showed 98% endothelialization of the anchor. Venograms revealed patent IVC and jugular veins in all animals at every time point examined. CONCLUSIONS: The PICD can be rapidly and chronically implanted in animals. Long-term intravascular defibrillator placement is feasible in a canine model
Dairy Farm Business Summary: Southeastern New York Region 1990
A.E. Ext. 91-17Dairy farmers throughout New York State have been participating in Cornell Cooperative Extension's farm business summary and analysis program since the early 1950's. Each participating farmer receives a comprehensive business summary and analysis of his or her farm business. The information in this report represents an average of the data submitted from farms in the Southeastern New York region
Structural investigation of sulfobetaines and phospholipid monolayers at the air-water interface
Mixtures of sulfobetaine based lipids with phosphocholine phospholipids are of interest in order to study the interactions between zwitterionic surfactants and the phospholipids present in cell membranes. In this study we have investigated the structure of mixed monolayers of sulfobetaines and phosphocholine phospholipids. The sulfobetaine used has a single 18-carbon tail, and is referred to as SB3-18, and the phospholipid used is DMPC. Surface pressure-area isotherms of the samples were used to determine whether any phase transitions were present during the compression of the monolayers. Neutron and X-ray reflectometry were then used to investigate the structure of these monolayers perpendicular to the interface. We found that the average headgroup and tail layer thickness was reasonably consistent across all mixtures, with a variation of less than 3 Å reported in the total thickness of the monolayers at each surface pressure. However, by selective deuteration of the two components of the monolayers, it was found that the two components have different tail layer thicknesses. For the mixture with equal compositions of DMPC and SB3-18 or with a higher composition of DMPC the tail tilts were found to be constant, resulting in a greater tail layer thickness for SB3-18 due to its longer tail. For the mixture higher in SB3-18 this was not the case, the tail tilt angle for the two components was found to be different and DMPC was found to have a greater tail layer thickness than SB3-18 as a result.</p
On the cohomology of pseudoeffective line bundles
The goal of this survey is to present various results concerning the
cohomology of pseudoeffective line bundles on compact K{\"a}hler manifolds, and
related properties of their multiplier ideal sheaves. In case the curvature is
strictly positive, the prototype is the well known Nadel vanishing theorem,
which is itself a generalized analytic version of the fundamental
Kawamata-Viehweg vanishing theorem of algebraic geometry. We are interested
here in the case where the curvature is merely semipositive in the sense of
currents, and the base manifold is not necessarily projective. In this
situation, one can still obtain interesting information on cohomology, e.g. a
Hard Lefschetz theorem with pseudoeffective coefficients, in the form of a
surjectivity statement for the Lefschetz map. More recently, Junyan Cao, in his
PhD thesis defended in Grenoble, obtained a general K{\"a}hler vanishing
theorem that depends on the concept of numerical dimension of a given
pseudoeffective line bundle. The proof of these results depends in a crucial
way on a general approximation result for closed (1,1)-currents, based on the
use of Bergman kernels, and the related intersection theory of currents.
Another important ingredient is the recent proof by Guan and Zhou of the strong
openness conjecture. As an application, we discuss a structure theorem for
compact K{\"a}hler threefolds without nontrivial subvarieties, following a
joint work with F.Campana and M.Verbitsky. We hope that these notes will serve
as a useful guide to the more detailed and more technical papers in the
literature; in some cases, we provide here substantially simplified proofs and
unifying viewpoints.Comment: 39 pages. This survey is a written account of a lecture given at the
Abel Symposium, Trondheim, July 201
Hyperholomorpic connections on coherent sheaves and stability
Let be a hyperkaehler manifold, and a torsion-free and reflexive
coherent sheaf on . Assume that (outside of its singularities) admits a
connection with a curvature which is invariant under the standard SU(2)-action
on 2-forms. If the curvature is square-integrable, then is stable and its
singularities are hyperkaehler subvarieties in . Such sheaves (called
hyperholomorphic sheaves) are well understood. In the present paper, we study
sheaves admitting a connection with SU(2)-invariant curvature which is not
necessarily square-integrable. This situation arises often, for instance, when
one deals with higher direct images of holomorphic bundles. We show that such
sheaves are stable.Comment: 37 pages, version 11, reference updated, corrected many minor errors
and typos found by the refere
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