Coupling of gaussian Schell-model beams into single-mode optical fibers.

We develop analytic equations that describe the mean and normalized variance of the coupling efficiency of gaussian Schell-model beams into single-mode optical fibers. Numerical methods and computer simulations are used to evaluate the accuracy of the various approximations used in this analysis, and, with some insight, empirical compensation is made for the identified shortcomings. The simulations make use of both speckled and nonspeckled beams by employing two different Monte Carlo methods to generate randomly drawn optical fields.

Multibeam scintillation cumulative distribution function.

The gamma-gamma probability density function is commonly used to model the scintillation of a single laser beam propagating through atmospheric turbulence. One method proposed to reduce scintillation at the receiver plane involves the use of multiple channels propagating through independent paths, resulting in a sum of independent gamma-gamma random variables. Recently, a novel approach for an accurate, closed-form approximation for the sum of independent, identically distributed gamma-gamma random variables was introduced by Chatzidiamantis et al.

Glass transitions in nanoscale heated volumes of thin polystyrene films.

Glass transitions in confined polystyrene films on a silicon substrate were studied using atomic force microscopy incorporating a thermal tip. Three-dimensional spatial nanoconfinements were achieved by controlling size and boundary conditions of small heated volumes of polymer nanostrands drawn from the polymer surface with the thermal tip, using appropriate loads and temperatures at the tip-polymer contact. Finite element analysis was performed to model mechanical contact and thermal transport, including the effects of contact radius, film thickness, and load on temperature and pressure distributions in the confined volume at the contact.

Remote identification and quantification of industrial smokestack effluents via imaging Fourier-transform spectroscopy.

Industrial smokestack plume emissions were remotely measured with a midwave infrared (1800-3000 cm(-1)) imaging Fourier-transform spectrometer operating at moderate spatial (128 × 64 with 19.4 × 19.4 cm(2) per pixel) and high spectral (0.

Enhanced material classification using turbulence-degraded polarimetric imagery.

An enhanced material-classification algorithm using turbulence-degraded polarimetric imagery is presented. The proposed technique improves upon an existing dielectric/metal material-classification algorithm by providing a more detailed object classification. This is accomplished by redesigning the degree-of-linear-polarization priors in the blind-deconvolution algorithm to include two subclasses of metals--an aluminum group classification (includes aluminum, copper, gold, and silver) and an iron group classification (includes iron, titanium, nickel, and chromium).

The Electronic Structure and Secondary Pyroelectric Properties of Lithium Tetraborate.

We review the pyroelectric properties and electronic structure of Li₂B₄O₇(110) and Li₂B₄O₇(100) surfaces. There is evidence for a pyroelectric current along the [110] direction of stoichiometric Li₂B₄O₇ so that the pyroelectric coefficient is nonzero but roughly 10³ smaller than along the [001] direction of spontaneous polarization. Abrupt decreases in the pyroelectric coefficient along the [110] direction can be correlated with anomalies in the elastic stiffness contributing to the concept that the pyroelectric coefficient is not simply a vector but has qualities of a tensor, as expected.

Electronic state distributions of YBa2Cu3O(7-x) laser-ablated plumes.

A systematic study of the spectrally resolved atomic emission arising from the laser ablation of YBa(2)Cu(3)O(7-x) targets in the presence of an oxygen background reveals statistically distributed populations with characteristic temporally averaged electronic temperatures of 0.28-0.38 eV, 0.

Insertion loss of noise barriers on an aboveground, full-scale model longwall coal mining shearer.

The U.S. mining industry struggles with hazardous noise and dust exposures in underground mining.

Bacterial enteritis as a risk factor for childhood intussusception: a retrospective cohort study.

Objective: To assess the relationship between bacterial enteritis and intussusception.

Study Design: The Patient Administration Systems and Biostatistics Activity database from January 2002 to December 2005 was examined for clinic visits or hospital admission to a Department of Defense medical facility for children age 0-5 years. The study included the International Statistical Classification of Diseases and Related Health Problems diagnosis-related group (DRG) codes for infections with Yersinia enterocolitica, Escherichia coli, Shigella species, Salmonella species, and Campylobacter.

Are you ready? How health professionals can comprehensively conceptualize readiness for change.

One important factor influencing the successful implementation of system-wide change is initial readiness. Readiness is defined as the degree to which those involved are individually and collectively primed, motivated, and technically capable of executing the change. We present a conceptual framework that highlights three broad areas to be considered if health-care professionals are to comprehensively evaluate readiness that includes psychological factors (i.

Local Histograms for Classifying H&E Stained Tissues.

We introduce a rigorous mathematical theory for the analysis of local histograms, and consider the appropriateness of their use in the automated classification of textures commonly encountered in images of H&E stained tissues. We first discuss some of the many image features that pathologists indicate they use when classifying tissues, focusing on simple, locally-defined features that essentially involve pixel counting: the number of cells in a region of given size, the size of the nuclei within these cells, and the distribution of color within both. We then introduce a probabilistic, occlusion-based model for textures that exhibit these features, in particular demonstrating how certain tissue-similar textures can be built up from simpler ones.

A geometrical optics polarimetric bidirectional reflectance distribution function for dielectric and metallic surfaces.

A polarimetric bidirectional reflectance distribution function (pBRDF), based on geometrical optics, is presented. The pBRDF incorporates a visibility (shadowing/masking) function and a Lambertian (diffuse) component which distinguishes it from other geometrical optics pBRDFs in literature. It is shown that these additions keep the pBRDF bounded (and thus a more realistic physical model) as the angle of incidence or observation approaches grazing and better able to model the behavior of light scattered from rough, reflective surfaces.

The environment value of an opponent model.

We develop an upper bound for the potential performance improvement of an agent using a best response to a model of an opponent instead of an uninformed game-theoretic equilibrium strategy. We show that the bound is a function of only the domain structure of an adversarial environment and does not depend on the actual actors in the environment. This bounds-finding technique will enable system designers to determine if and what type of opponent models would be profitable in a given adversarial environment.

Crossed-beam intermodulated fluorescence spectroscopy as a spatially resolved temperature diagnostic for supersonic nozzles.

A variant of laser saturation spectroscopy has been applied to the determination of spatially resolved temperature in low-pressure supersonic flows. By copropagating a pump and probe beam with a small crossing angle, the full Doppler profile is retained, but the signal is limited to the volume where both beams are overlapped. The technique was demonstrated on several rovibrational lines of the I2X1Sigma(0g+)-->B3Pi(0u+) transition in a Mach 2 Laval nozzle.

Path-averaged Cn2 estimation using a laser-and-corner-cube system.

As a finite cross-section laser beam propagates through the atmosphere, the beam spreads due to both diffraction and atmospheric turbulence effects. Using turbulence theory valid in both weak and strong optical turbulence regimes, a relationship between atmospheric beam spread and the resulting return power for an optical system and the refractive-index structure parameter or Cn2 can be established. A technique for estimating the path-averaged Cn2 using a laser-and-corner-cube system based on this relationship is described.

Chain-length effects on conformations of methyl methacrylate-oligomer thin films on an Au(111) substrate.

Molecular dynamics simulations were employed to investigate chain-length effects on conformations of methyl methacrylate (MMA)-oligomer thin films on an Au(111) substrate. Some observations were obtained from the present research. For short chain films, there is a sharp peak in the density profile of the MMA monomers for the adsorption region and the thin films exhibit a flattened conformation in the adsorption and the surface regions.

Validation of two innovative methods to measure contaminant mass flux in groundwater.

The ability to quantify the mass flux of a groundwater contaminant that is leaching from a source area is critical to enable us to: (1) evaluate the risk posed by the contamination source and prioritize cleanup, (2) evaluate the effectiveness of source remediation technologies or natural attenuation processes, and (3) quantify a source term for use in models that may be applied to predict maximum contaminant concentrations in downstream wells. Recently, a number of new methods have been developed and subsequently applied to measure contaminant mass flux in groundwater in the field. However, none of these methods has been validated at larger than the laboratory-scale through a comparison of measured mass flux and a known flux that has been introduced into flowing groundwater.

Development of a Korean version of a core self-evaluations scale.

The present study tested a scale which measures core self-evaluation and was applied to two samples of Korean military members (Sample 1 N=181; Sample 2 N=280). Analysis indicated that seven items of the original 12-item scale developed by Judge, Erez, Bono, and Thoresen loaded on one factor and were internally consistent. Moreover, scores were correlated, as expected, with the four core traits which have been used as indirect measures of core self-evaluations (viz.

Modeling the in vivo case with in vitro nanotoxicity data.

As more in vitro nanotoxicity data appear in the literature, these findings must be translated to in vivo effects to define nanoparticle exposure risk. Physiologically based pharmacokinetic (PBPK) modeling has played a significant role in guiding and validating in vivo studies for molecular chemical exposure and can develop as a significant tool in guiding similar nanotoxicity studies. This study models the population dynamics of a single cell type within a specific tissue.

Maximizing the effectiveness of a pediatric vaccine formulary while prohibiting extraimmunization.

The growing-complexity of the United States Recommended Childhood Immunization Schedule has resulted in as many as five required injections during a single well-baby office visit. To reduce this number, vaccine manufacturers have developed combination vaccines that immunize against several diseases in a single injection. At the same time, a growing number of parents are challenging the safety and effectiveness of vaccinating children.

Controlling the transmitted field into a cylindrical cloak's hidden region.

Constitutive parameters for simplified cylindrical cloaks have been developed such that epsilon(z)micro(theta) and epsilon(z)micro(r) match those of the ideal cylindrical cloak. Although they are not perfect, simplified cylindrical cloaks have been shown to inherit many of the power-bending properties of the ideal cloak. However, energy is transmitted into simplified cloaks hidden regions.

Nondestructive evaluation of aircraft composites using transmissive terahertz time domain spectroscopy.

Terahertz time domain spectroscopy (TDS) was assessed as a nondestructive evaluation technique for aircraft composites. Damage to glass fiber was studied including voids, delaminations, mechanical damage, and heat damage. Measurement of the material properties on samples with localized heat damage showed that burning did not change the refractive index or absorption coefficient noticeably; however, material blistering was detected.

Bound on range precision for shot-noise limited ladar systems.

The precision of ladar range measurements is limited by noise. The fundamental source of noise in a laser signal is the random time between photon arrivals. This phenomenon, called shot noise, is modeled as a Poisson random process.

Multichannel blind deconvolution of polarimetric imagery.

A maximum likelihood blind deconvolution algorithm is derived for incoherent polarimetric imagery using expectation maximization. In this approach, the unpolarized and fully polarized components of the scene are estimated along with the corresponding angles of polarization and channel point spread functions. The scene state of linear polarization is determined unambiguously using this parameterization.