A monolithic MQW InP-InGaAsP-Based optical comb generator

We report the first demonstration of a monolithic optical-frequency comb generator. The device is based on multi-section quaternary/quaternary eight-quantum-well InP-InGaAsP material in a frequency-modulated (FM) laser design. The modulation is generated using quantum-confined Stark-effect phase-induced refractive index modulation to achieve fast modulation up to 24.4 GHz. The laser was fabricated using a single epitaxial growth step and quantum-well intermixing to realize low-loss phase adjustment and modulation sections. The output was quasicontinuous wave with intensity modulation at less than 20% for a total output power of 2 mW. The linewidth of each line was limited by the linewidth of the free running laser at an optimum of 25 MHz full-width at half-maximum. The comb generator produces a number of lines with a spacing exactly equal to the modulation frequency (or a multiple of it), differential phase noise between adjacent lines of -82 dBc/Hz at 1-kHz offset (modulation source-limited), and a potential comb spectrum width of up to 2 THz (15 nm), though the comb spectrum was not continuous across the full span

A monolithic MQW InP/InGaAsP-based comb generator

We report a monolithic optical frequency comb generator using quaternary/quaternary multiple quantum well InV/InGaAsP material as phase modulator and gain medium in a Frequency Modulated (FM) laser design. The modulation was generated by quantum confined Stark effect to achieve a comb-line spacing of 24.4 GHz. The laser was fabricated using a single epitaxial growth step and quantum well intermixing to realize low loss phase and modulation sections. The resulting comb generator produces lines with a spacing exactly given by the modulation frequency, differential phase noise between adjacent lines of -82 dBc/Hz at 1 kHz offset and a comb spectrum width of up to 2 THz

Shape of Deconstruction

We construct a six-dimensional Maxwell theory using a latticized extra space, the continuum limit of which is a shifted torus recently discussed by Dienes. This toy model exhibits the correspondence between continuum theory and discrete theory, and give a geometrical insight to theory-space model building.Comment: 10 pages, 2 figures, RevTeX4. a citation adde

Spatiotemporal Calibration of Atmospheric Nitrogen Dioxide Concentration Estimates From an Air Quality Model for Connecticut

A spatiotemporal calibration and resolution refinement model was fitted to calibrate nitrogen dioxide (NO$_2$) concentration estimates from the Community Multiscale Air Quality (CMAQ) model, using two sources of observed data on NO$_2$ that differed in their spatial and temporal resolutions. To refine the spatial resolution of the CMAQ model estimates, we leveraged information using additional local covariates including total traffic volume within 2 km, population density, elevation, and land use characteristics. Predictions from this model greatly improved the bias in the CMAQ estimates, as observed by the much lower mean squared error (MSE) at the NO$_2$ monitor sites. The final model was used to predict the daily concentration of ambient NO$_2$ over the entire state of Connecticut on a grid with pixels of size 300 x 300 m. A comparison of the prediction map with a similar map for the CMAQ estimates showed marked improvement in the spatial resolution. The effect of local covariates was evident in the finer spatial resolution map, where the contribution of traffic on major highways to ambient NO$_2$ concentration stands out. An animation was also provided to show the change in the concentration of ambient NO$_2$ over space and time for 1994 and 1995.Comment: 23 pages, 8 figures, supplementary materia

IT Industry Analysts: A Review and Two Research Agendas

The firms involved in analyzing the information technology industry (IT), such as Gartner, Forrester, and IDC, are reputed to have a major impact on both IT vendors and IT adopters through their influence over how IT actually is acquired and used. The purpose of this article is to take stock of the nascent stream of research on industry analysts that has developed in recent years in order to shed some light on the IT analysis industry―to analyze the IT industry analysts, if you will. Using an organizational field-level lens, we look at the business models of the firms that operate in this industry. We examine the main institutional work that the analysts in these firms perform as status arbiters, institutional carriers, network brokers, IT fashion setters, and knowledge entrepreneurs. We examine the competitive and institutional pressures faced by analysts in these firms. Finally, we propose two research agendas: (1) to study the impact that this industry has had, and could continue to have, on the IT industry as a whole, and (2) to study how the relationship between the academic information systems community and the IT analysis industry might co-evolve

D-type supersymmetry breaking and brane-to-brane gravity mediation

We revisit the issue of gravitational contributions to soft masses in five-dimensional sequestered models. We point out that, unlike for the case of F-type supersymmetry breaking, for D-type breaking these effects generically give positive soft masses squared for the sfermions. This drastically improves model building. We discuss the phenomenological implications of our result.Comment: 16 pages. Typos corrected, minor clarifications. To be published in Phys. Lett.

O-36: The orally active renin inhibitor SPP100 blocks the renin-angiotensin system in humans equally well as enalapril

The activity of the renin-angiotensin system (RAS) is mainly determined by the concentration of active renin. Direct inhibition of renin is therefore a primary goal for blocking the RAS. So far, all specific renin inhibitors lacked potency or were clinically ineffective after oral administration. We tested the new orally active non-peptidic renin inhibitor SPP100 in 18 healthy volunteers on a constant sodium diet (100 mmol/day)using a double-blind, threeway crossover protocol. In 3 periods of 8 days, separated by wash-outs of 1 week, each volunteer received 2 dosage levels of SPP100 once a day (40,80,160 or 640mg) and placebo or 20mg enalapril. SPP100 was well tolerated. Not surprisingly, blood pressure and heart rate remained unchanged in these normal volunteers. SPP100 plasma levels showed that steady state was reached after 8 days of dosing. The table below summarizes median plasma levels at peak (P, 0.5-6h) and trough (T, 24h after dosing)on day 8: In conclusion, the renin inhibitor SPP100 dose-dependently blocks the RAS and decreases angiotensin levels in human subjects following oral administration. The effect is long-lasting and at 160mg at least equivalent to that of 20mg enalapril. SPP100 has the clear potential to become the first renin inhibitor that provides a true alternative to ACE-inhibitors and Ang II receptor antagonists in the therapy of hypertension, cardiovascular and renal disease. Placebo SPP 100 Enalapril 40mg 80mg 160mg 640mg 20mg Renin pg/ml P 12 34 95 130 670 330 T 11 19 39 64 373 58 PRA ng/ml/h P 1.0 0.28 0.21 0.16 0.08 27 T 1.4 0.89 0.60 0.41 0.39 3.5 Ang I fmol/ml P 3.2 1.6 1.4 0.33 0.70 350 T 7.0 7.1 6.1 4.8 3.1 34 Ang II fmol/ml P 3.0 1.5 1.5 0.61 0.27 0.88 T 4.5 3.7 3.5 3.2 2.5 4.

A wavelet transform algorithm for peak detection and application to powder x-ray diffraction data

Peak detection is ubiquitous in the analysis of spectral data. While many noise-filtering algorithms and peak identification algorithms have been developed, recent work [P. Du, W. Kibbe, and S. Lin, Bioinformatics 22, 2059 (2006); A. Wee, D. Grayden, Y. Zhu, K. Petkovic-Duran, and D. Smith, Electrophoresis 29, 4215 (2008)] has demonstrated that both of these tasks are efficiently performed through analysis of the wavelet transform of the data. In this paper, we present a wavelet-based peak detection algorithm with user-defined parameters that can be readily applied to the application of any spectral data. Particular attention is given to the algorithm's resolution of overlapping peaks. The algorithm is implemented for the analysis of powder diffraction data, and successful detection of Bragg peaks is demonstrated for both low signal-to-noise data from theta–theta diffraction of nanoparticles and combinatorial x-ray diffraction data from a composition spread thin film. These datasets have different types of background signals which are effectively removed in the wavelet-based method, and the results demonstrate that the algorithm provides a robust method for automated peak detection

A wavelet transform algorithm for peak detection and application to powder x-ray diffraction data

Peak detection is ubiquitous in the analysis of spectral data. While many noise-filtering algorithms and peak identification algorithms have been developed, recent work [P. Du, W. Kibbe, and S. Lin, Bioinformatics 22, 2059 (2006); A. Wee, D. Grayden, Y. Zhu, K. Petkovic-Duran, and D. Smith, Electrophoresis 29, 4215 (2008)] has demonstrated that both of these tasks are efficiently performed through analysis of the wavelet transform of the data. In this paper, we present a wavelet-based peak detection algorithm with user-defined parameters that can be readily applied to the application of any spectral data. Particular attention is given to the algorithm's resolution of overlapping peaks. The algorithm is implemented for the analysis of powder diffraction data, and successful detection of Bragg peaks is demonstrated for both low signal-to-noise data from theta–theta diffraction of nanoparticles and combinatorial x-ray diffraction data from a composition spread thin film. These datasets have different types of background signals which are effectively removed in the wavelet-based method, and the results demonstrate that the algorithm provides a robust method for automated peak detection