6.25 Gb/s POF link using GaN μLED arrays and optically generated pulse amplitude modulation

Optically-generated PAM schemes using μLED arrays are implemented for high-speed POF links for the first time. 6.25Gb/s PAM-16 transmission is demonstrated using 4 μLEDs, exhibiting 3.8dB greater power-margin than a link with a single μLED.This work is supported by the UK Engineering and Physical Sciences Research Council (EPSRC) via the Ultra Parallel Visible Light Communication (UP-VLC) Project.This is the accepted manuscript of a paper published in CLEO: 2015 (X. Li, N. Bamiedakis, J. Wei, J. Mckendry, E. Xie, R. Ferreira, E. Gu, M. Dawson, R. V. Penty, and I. H. White, "6.25 Gb/s POF Link Using GaN μLED Arrays and Optically Generated Pulse Amplitude Modulation," in CLEO: 2015, OSA Technical Digest (online) (Optical Society of America, 2015), paper STu4F.7.). The final version is available at http://dx.doi.org/10.1364/CLEO_SI.2015.STu4F.7 © 2015 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited

Perturbations of nuclear C*-algebras

Kadison and Kastler introduced a natural metric on the collection of all C*-subalgebras of the bounded operators on a separable Hilbert space. They conjectured that sufficiently close algebras are unitarily conjugate. We establish this conjecture when one algebra is separable and nuclear. We also consider one-sided versions of these notions, and we obtain embeddings from certain near inclusions involving separable nuclear C*-algebras. At the end of the paper we demonstrate how our methods lead to improved characterisations of some of the types of algebras that are of current interest in the classification programme.Comment: 45 page

Elastomeric spring actuator using nylon wires

Medical devices are designed for collaboration with the human body, which makes the steps to create them increasingly more complex if the device is to be implanted. Soft robots have the unique potential of meeting both the mechanical compliance with the interacting tissues and the controlled functionality needed for a repair or replacement. Soft devices that fulfill fundamental mechanical roles are needed as parts of soft robots in order to carry out desired tasks. As the medical devices become increasingly low-profile, soft devices must feature multi-functionality that is embedded in the structure. A device embedded with nylon actuators allows for the controlled collapsing of an elastomeric spring by compression alone or compression and twisting. In this paper we present the concept of a novel elastomeric spring, its fabrication and mechanical characterization

μlED-Based Single-Wavelength Bi-directional POF Link with 10 Gb/s Aggregate Data Rate

We report record 10 Gb/s bi-directional data transmission over a single 10 m SI-POF, by employing blue micro-light-emitting diodes (μLEDs) at a single wavelength, APD receivers and a PAM-32 modulation scheme. The implementation of 10 Gb/s LED-POF links takes advantage of the bi-directional configuration, which doubles the overall channel capacity, and APDs which provide an enhanced link power budget owing to their improved sensitivity compared with conventional PIN photodiodes. Moreover, the high spectral efficiency of the PAM-32 modulation scheme employed, together with equalization techniques, enable the full utilization of the link bandwidth and the transmission of data rates higher than those obtained with conventional on-off-keying (OOK). Simulation and experimental results demonstrate the feasibility of such a bi-directional link and simultaneous 5 Gb/s data transmission is realized in each direction, achieving an aggregate data rate of 10 Gb/s with a BER<10-3. The crosstalk penalty between the two directions of the link is measured to be less than 0.5 dB.This is the final version of the article. It first appeared from IEEE via http://dx.doi.org/10.1109/JLT.2015.244398

2 Gb/s μlED-APD based visible light communications using feed-forward pre-equalization and PAM-4 modulation

Feed-forward pre-equalization is investigated to extend the transmission capability of μLED-based links, providing better receiver sensitivities up to 5dB compared with post-equalization. Error-free 2Gb/s free-space VLC over 0.6m is demonstrated using a PAM-4 modulated blue μLED and an APD receiver.This work is supported by the UK EPSRC via the UPVLC Project.This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/ECOC.2015.734188

Laser cooling of a diatomic molecule

It has been roughly three decades since laser cooling techniques produced ultracold atoms, leading to rapid advances in a vast array of fields. Unfortunately laser cooling has not yet been extended to molecules because of their complex internal structure. However, this complexity makes molecules potentially useful for many applications. For example, heteronuclear molecules possess permanent electric dipole moments which lead to long-range, tunable, anisotropic dipole-dipole interactions. The combination of the dipole-dipole interaction and the precise control over molecular degrees of freedom possible at ultracold temperatures make ultracold molecules attractive candidates for use in quantum simulation of condensed matter systems and quantum computation. Also ultracold molecules may provide unique opportunities for studying chemical dynamics and for tests of fundamental symmetries. Here we experimentally demonstrate laser cooling of the molecule strontium monofluoride (SrF). Using an optical cycling scheme requiring only three lasers, we have observed both Sisyphus and Doppler cooling forces which have substantially reduced the transverse temperature of a SrF molecular beam. Currently the only technique for producing ultracold molecules is by binding together ultracold alkali atoms through Feshbach resonance or photoassociation. By contrast, different proposed applications for ultracold molecules require a variety of molecular energy-level structures. Our method provides a new route to ultracold temperatures for molecules. In particular it bridges the gap between ultracold temperatures and the ~1 K temperatures attainable with directly cooled molecules (e.g. cryogenic buffer gas cooling or decelerated supersonic beams). Ultimately our technique should enable the production of large samples of molecules at ultracold temperatures for species that are chemically distinct from bialkalis.Comment: 10 pages, 7 figure

Sampling constrained probability distributions using Spherical Augmentation

Statistical models with constrained probability distributions are abundant in machine learning. Some examples include regression models with norm constraints (e.g., Lasso), probit, many copula models, and latent Dirichlet allocation (LDA). Bayesian inference involving probability distributions confined to constrained domains could be quite challenging for commonly used sampling algorithms. In this paper, we propose a novel augmentation technique that handles a wide range of constraints by mapping the constrained domain to a sphere in the augmented space. By moving freely on the surface of this sphere, sampling algorithms handle constraints implicitly and generate proposals that remain within boundaries when mapped back to the original space. Our proposed method, called {Spherical Augmentation}, provides a mathematically natural and computationally efficient framework for sampling from constrained probability distributions. We show the advantages of our method over state-of-the-art sampling algorithms, such as exact Hamiltonian Monte Carlo, using several examples including truncated Gaussian distributions, Bayesian Lasso, Bayesian bridge regression, reconstruction of quantized stationary Gaussian process, and LDA for topic modeling.Comment: 41 pages, 13 figure

High speed plastic optical fiber data links using LEDs

Manuscript originally submitted to the repository as for publication by IEEE in the papers of the International Conference On Communication Problem-Solving (ICCP2014). However, it does not appear among the published papers for this conference, and no reference has been found to it being published elsewhere.Plastic optical fiber (POF) data links have been widely viewed as a cost- and energy- effective solutions for short-reach Gigabit data communications such as in-home and automotive networks. POF also has excellent compatibility with low-cost light-emitting-diodes (LEDs). In this paper, we demonstrate a 4 Gb/s single micro-LED (μLED) PAM-16 link and a record 4.7 Gb/s multiple μLEDs PAM-8 link by 1) use of avalanche photodiodes (APD) in combination with high order modulation formats; and 2) illumination of multiple μLEDs. Both digital implementation based on FPGA and analogue implementation are considered for real-time transmitters

A Novel Mutation in the Upstream Open Reading Frame of the CDKN1B Gene Causes a MEN4 Phenotype

PubMed ID: 23555276This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited