A Few Photons Among Many: Unmixing Signal and Noise for Photon-Efficient Active Imaging

Conventional LIDAR systems require hundreds or thousands of photon detections to form accurate depth and reflectivity images. Recent photon-efficient computational imaging methods are remarkably effective with only 1.0 to 3.0 detected photons per pixel, but they are not demonstrated at signal-to-background ratio (SBR) below 1.0 because their imaging accuracies degrade significantly in the presence of high background noise. We introduce a new approach to depth and reflectivity estimation that focuses on unmixing contributions from signal and noise sources. At each pixel in an image, short-duration range gates are adaptively determined and applied to remove detections likely to be due to noise. For pixels with too few detections to perform this censoring accurately, we borrow data from neighboring pixels to improve depth estimates, where the neighborhood formation is also adaptive to scene content. Algorithm performance is demonstrated on experimental data at varying levels of noise. Results show improved performance of both reflectivity and depth estimates over state-of-the-art methods, especially at low signal-to-background ratios. In particular, accurate imaging is demonstrated with SBR as low as 0.04. This validation of a photon-efficient, noise-tolerant method demonstrates the viability of rapid, long-range, and low-power LIDAR imaging

Induced symmetry breaking and a new phase of hadronic matter at high density

The notion induced symmetry breaking (ISB) is introduced as a generalization of the spontaneous symmetry breaking mechanism and is illustrated in a simple two flavor spin model. In the case of QCD at finite baryon density, I argue that the quark interaction induced by zero sound satisfies the prerequisites which are necessary for a ISB scenario. In this scenario, the quark condensate sharply drops at the critical value of the chemical potential in coincidence with a rapid increase of the baryon density. The spectrum of the light particles is discussed below and above this phase transition. The consequences of the ISB mechanism for heavy ion collisions are briefly addressed.Comment: 6 pages, 5 figures, Talk presented at the workshop ''QCD at finite baryon density'', Zif, Bielefeld, April 27-30, 1998, submitted to Nucl. Phys.

Medium Modifications of Charm and Charmonium in High-Energy Heavy-Ion Collisions

The production of charmonia in heavy-ion collisions is investigated within a kinetic theory framework simultaneously accounting for dissociation and regeneration processes in both quark-gluon plasma (QGP) and hadron-gas phases of the reaction. In-medium modifications of open-charm states (c-quarks, D-mesons) and the survival of J/psi mesons in the QGP are included as inferred from lattice QCD. Pertinent consequences on equilibrium charmonium abundances are evaluated and found to be especially relevant to explain the measured centrality dependence of the psi'/psi ratio at SPS. Predictions for recent In-In experiments, as well as comparisons to current Au-Au data from RHIC, are provided.Comment: 4 Latex pages including 4 eps figures and IOP style files. Talk given at the 17th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Quark Matter 2004, Oakland, CA USA, 11-17 Jan 2004. To appear in J. Phys.

The Ohio State 1991 geopotential and sea surface topography harmonic coefficient models

The computation is described of a geopotential model to deg 360, a sea surface topography model to deg 10/15, and adjusted Geosat orbits for the first year of the exact repeat mission (ERM). This study started from the GEM-T2 potential coefficient model and it's error covariance matrix and Geosat orbits (for 22 ERMs) computed by Haines et al. using the GEM-T2 model. The first step followed the general procedures which use a radial orbit error theory originally developed by English. The Geosat data was processed to find corrections to the a priori geopotential model, corrections to a radial orbit error model for 76 Geosat arcs, and coefficients of a harmonic representation of the sea surface topography. The second stage of the analysis took place by doing a combination of the GEM-T2 coefficients with 30 deg gravity data derived from surface gravity data and anomalies obtained from altimeter data. The analysis has shown how a high degree spherical harmonic model can be determined combining the best aspects of two different analysis techniques. The error analysis was described that has led to the accuracy estimates for all the coefficients to deg 360. Significant work is needed to improve the modeling effort

Dead Time Compensation for High-Flux Ranging

Dead time effects have been considered a major limitation for fast data acquisition in various time-correlated single photon counting applications, since a commonly adopted approach for dead time mitigation is to operate in the low-flux regime where dead time effects can be ignored. Through the application of lidar ranging, this work explores the empirical distribution of detection times in the presence of dead time and demonstrates that an accurate statistical model can result in reduced ranging error with shorter data acquisition time when operating in the high-flux regime. Specifically, we show that the empirical distribution of detection times converges to the stationary distribution of a Markov chain. Depth estimation can then be performed by passing the empirical distribution through a filter matched to the stationary distribution. Moreover, based on the Markov chain model, we formulate the recovery of arrival distribution from detection distribution as a nonlinear inverse problem and solve it via provably convergent mathematical optimization. By comparing per-detection Fisher information for depth estimation from high- and low-flux detection time distributions, we provide an analytical basis for possible improvement of ranging performance resulting from the presence of dead time. Finally, we demonstrate the effectiveness of our formulation and algorithm via simulations of lidar ranging.Comment: Revision with added estimation results, references, and figures, and modified appendice

Recent H-mode density limit studies at JET

Extensive studies of the H-mode density limit (DL) in JET gas-puffed discharges have been performed in the past four years targeting at an improved database for extrapolation to ITER. This paper reviews the arguments for the particular DL definition (pedestal density at the H-L boundary), the logic underlying the choice of parameters under focus (toroidal field, major radius, triangularity, safety factor) as well as some improvement in the interpretation of typical JET density ramp-up signatures that led to a critical review of the existing data. An empirical scaling is derived and compared with existing empirical and model based scalings. ASDEX Upgrade data are included in this analysis to provide information on the size dependence. The main results are: earlier findings on the B-t, R and q(95)-dependences are confirmed. The triangularity dependence, if any, is weak. The SOL-based BLS (Borrass, Lingertat, Schneider) scaling and the empirical scaling are virtually indistinguishable. The Greenwald scaling provides values in the right absolute range, but the overall fit is comparatively poor. The proposed scaling predicts ITER critical densities considerably below the reference value. Fuelling methods other than gas-puffing are outside the scope of this paper, but pellet fuelling, envisaged for ITER as an option to alleviate the situation, is discussed

Self-consistent parametrization of the two-flavor isotropic color-superconducting ground state

Lack of Lorentz invariance of QCD at finite quark chemical potential in general implies the need of Lorentz non-invariant condensates for the self-consistent description of the color-superconducting ground state. Moreover, the spontaneous breakdown of color SU(3) in this state naturally leads to the existence of SU(3) non-invariant non-superconducting expectation values. We illustrate these observations by analyzing the properties of an effective 2-flavor Nambu-Jona-Lasinio type Lagrangian and discuss the possibility of color-superconducting states with effectively gapless fermionic excitations. It turns out that the effect of condensates so far neglected can yield new interesting phenomena.Comment: 16 pages, 3 figure

Dileptons in High-Energy Heavy-Ion Collisions

The current status of our understanding of dilepton production in ultrarelativistic heavy-ion collisions is discussed with special emphasis on signals from the (approach towards) chirally restored and deconfined phases. In particular, recent results of the CERN-SPS low-energy runs are compared to model predictions and interpreted. Prospects for RHIC experiments are given.Comment: Invited talk at ICPAQGP, Jaipur, India, Nov. 26-30, 2001; 1 Latex and 9 eps-/ps-files Reoprt No.: SUNY-NTG-02-0

Dispersal Abilities Of Seven Sparse And Common Grasses From A Missouri Prairie

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142240/1/ajb212393.pd

Leadership as a bottleneck factor in CRM. Or: What could be learned from Alinghi

El profesionalismo y la administración de relaciones con el cliente no se detienen con los sistemas y estrategias, el éxito real de los acercamientos prometedores sólo se puede lograr por medio de una nueva orientación y administración. Esto incluye la comprensión de la administración como un marco de referencia existencial que está basado en la confianza, ya que todos los ejemplos presentados muestran que el CRMtrata con nuevas situaciones, pruebas, problemas y errores, además de cómo tratar con incidentes inesperados. Cuando un gerente no es capaz de mostrar fe en sus empleados y de establecer una administración que ve los errores de forma positiva (el error como la mejor forma de aprendizaje) como base de la organización, las mejores auditorías y los mejores procedimientos están perdidos. si este entendido básico es probable que exista en algún lado, resultados positivos del CRM pueden ser obtenidos a corto plazo, debido a análisis consecuentes y a la realización de lineamientos a seguir  —y con la introspección continua y la repetición de procedimientos, los cuales pueden servir como ventaja competitiva independiente para un individuo en particular