10Gbit/s modulation of a fast switching slotted Fabry-Pérot tunable laser

The device used is a three-section, 3mum wide ridge waveguide laser based on commercially available material. During the fabrication a series of slots are introduced into the front and back sections, which act as sites of internal reflections. The slots are etched to a depth that just penetrates the top of the upper waveguide resulting in an internal reflectance of-1% at each slot. The front, middle, and back sections are 180, 690 and 170 microns long respectively. In this work the back and middle sections are tied together electrically allowing simpler control of the device. By varying the applied DC currents, eight discrete channels are observed over a range of approximately 19nm

Experimentation and self learning in continuous database marketing

We present a method for continuous database marketing that identifies target customers for a number of marketing offers using predictive models. The algorithm then selects the appropriate offer for the customer. Experimental design principles are encapsulated to capture more information that will be used to monitor and refine the predictive models. The updated predictive models are then used for the next round of marketing offers.<br /

Bryophytes of Uganda : 6., new and additional records, 3.

12 hepatics and 32 mosses are reported new to Uganda, 1 moss being also new to Africa, and 1 liverwort new to mainland Africa. Ectropothecium plumigerum (Broth.) Hedenäs is a new combination (basionym: Isopterygium plumigerum Broth.) with a new synonym Taxicaulis plumirameus Müll.Hal. nom. nud., and Taxiphyllum maniae (Renauld & Paris) M. Fleisch. is a new synonym of Taxiphyllum taxirameum (Mitt.) M.Fleisch. Three mosses are removed from the Uganda list

Parity and Time Reversal in the Spin-Rotation Interaction

A recently reported discrepancy between experimental and theoretical values of the muon's g-2 factor is interpreted as due to small violations of the conservation of P and T in the spin-rotation coupling. The experiments place an upper limit on these violations and on the weight change of spinning gyroscopes.Comment: 3 page

3 præsentationer fra Økologisk-Kongres 2017

3 præsentationer fra pEcoSystem projektet til Økologi-Kongress 2017 1)Bedre grisemiljø versus lavere klima- og miljøpåvirkning? Eller både og? 2)10 ugers fravænning 3)Træer i folde fordele og ulempe

Checkerboard local density of states in striped domains pinned by vortices

Within a Green's function formalism we calculate the electronic structure around static extended magnetic and non-magnetic perturbations in a d-wave superconductor. In partucular, we discuss recent elastic neutron scattering and scanning tunneling experiments on High-T_c cuprates exposed to an applied magnetic field. A physical picture consisting of antiferromagnetic vortex cores operating as pinning centers for surrounding stripes is qualitatively consistent with the neutron data provided the stripes have the usual antiphase modulation. The low energy electronic structure in such a region reveals a checkerboard interference pattern consistent with recent scanning tunneling experiments.Comment: 5 pages, 4 figure

A generic estimate of trans-Planckian modifications to the primordial power spectrum in inflation

We derive a general expression for the power spectra of scalar and tensor fluctuations generated during inflation given an arbitrary choice of boundary condition for the mode function at a short distance. We assume that the boundary condition is specified at a short-distance cutoff at a scale $M$ which is independent of time. Using a particular prescription for the boundary condition at momentum $p = M$, we find that the modulation to the power spectra of density and gravitational wave fluctuations is of order $(H/M)$, where $H$ is the Hubble parameter during inflation, and we argue that this behavior is generic, although by no means inevitable. With fixed boundary condition, we find that the shape of the modulation to the power spectra is determined entirely by the deviation of the background spacetime from the de Sitter limit.Comment: 15 pages (RevTeX), 2 figure

Two nonmagnetic impurities in the DSC and DDW state of the cuprate superconductors as a probe for the pseudogap

The quantum interference between two nonmagnetic impurities is studied numerically in both the d-wave superconducting (DSC) and the d-density wave (DDW) state. In all calculations we include the tunnelling through excited states from the CuO$_2$ planes to the BiO layer probed by the STM tip. Compared to the single impurity case, a systematic study of the modulations in the two-impurity local density of states can distinguish between the DSC or DDW states. This is important if the origin of the pseudogap phase is caused by preformed pairs or DDW order. Furthermore, in the DSC state the study of the LDOS around two nonmagnetic impurities provide further tests for the potential scattering model versus more strongly correlated models.Comment: 6 pages, 6 figure

Nucleosynthesis Constraints on a Massive Gravitino in Neutralino Dark Matter Scenarios

The decays of massive gravitinos into neutralino dark matter particles and Standard Model secondaries during or after Big-Bang nucleosynthesis (BBN) may alter the primordial light-element abundances. We present here details of a new suite of codes for evaluating such effects, including a new treatment based on PYTHIA of the evolution of showers induced by hadronic decays of massive, unstable particles such as a gravitino. We also develop an analytical treatment of non-thermal hadron propagation in the early universe, and use this to derive analytical estimates for light-element production and in turn on decaying particle lifetimes and abundances. We then consider specifically the case of an unstable massive gravitino within the constrained minimal supersymmetric extension of the Standard Model (CMSSM). We present upper limits on its possible primordial abundance before decay for different possible gravitino masses, with CMSSM parameters along strips where the lightest neutralino provides all the astrophysical cold dark matter density. We do not find any CMSSM solution to the cosmological Li7 problem for small m_{3/2}. Discounting this, for m_{1/2} ~ 500 GeV and tan beta = 10 the other light-element abundances impose an upper limit m_{3/2} n_{3/2}/n_\gamma < 3 \times 10^{-12} GeV to < 2 \times 10^{-13} GeV for m_{3/2} = 250 GeV to 1 TeV, which is similar in both the coannihilation and focus-point strips and somewhat weaker for tan beta = 50, particularly for larger m_{1/2}. The constraints also weaken in general for larger m_{3/2}, and for m_{3/2} > 3 TeV we find a narrow range of m_{3/2} n_{3/2}/n_\gamma, at values which increase with m_{3/2}, where the Li7 abundance is marginally compatible with the other light-element abundances.Comment: 74 pages, 40 Figure

Cosmological parameters from SDSS and WMAP

We measure cosmological parameters using the three-dimensional power spectrum P(k) from over 200,000 galaxies in the Sloan Digital Sky Survey (SDSS) in combination with WMAP and other data. Our results are consistent with a ``vanilla'' flat adiabatic Lambda-CDM model without tilt (n=1), running tilt, tensor modes or massive neutrinos. Adding SDSS information more than halves the WMAP-only error bars on some parameters, tightening 1 sigma constraints on the Hubble parameter from h~0.74+0.18-0.07 to h~0.70+0.04-0.03, on the matter density from Omega_m~0.25+/-0.10 to Omega_m~0.30+/-0.04 (1 sigma) and on neutrino masses from <11 eV to <0.6 eV (95%). SDSS helps even more when dropping prior assumptions about curvature, neutrinos, tensor modes and the equation of state. Our results are in substantial agreement with the joint analysis of WMAP and the 2dF Galaxy Redshift Survey, which is an impressive consistency check with independent redshift survey data and analysis techniques. In this paper, we place particular emphasis on clarifying the physical origin of the constraints, i.e., what we do and do not know when using different data sets and prior assumptions. For instance, dropping the assumption that space is perfectly flat, the WMAP-only constraint on the measured age of the Universe tightens from t0~16.3+2.3-1.8 Gyr to t0~14.1+1.0-0.9 Gyr by adding SDSS and SN Ia data. Including tensors, running tilt, neutrino mass and equation of state in the list of free parameters, many constraints are still quite weak, but future cosmological measurements from SDSS and other sources should allow these to be substantially tightened.Comment: Minor revisions to match accepted PRD version. SDSS data and ppt figures available at http://www.hep.upenn.edu/~max/sdsspars.htm