Analysing the length of care episode after hip fracture: a nonparametric and a parametric Bayesian approach.

Effective utilisation of limited resources is a challenge for health care providers. Accurate and relevant information extracted from the length of stay distributions is useful for management purposes. Patient care episodes can be reconstructed from the comprehensive health registers, and in this paper we develop a Bayesian approach to analyse the length of care episode after a fractured hip.

Spectral irradiance model for tungsten halogen lamps in 340-850 nm wavelength range.

We have developed a physical model for the spectral irradiance of 1 kW tungsten halogen incandescent lamps for the wavelength range 340-850 nm. The model consists of the Planck's radiation law, published values for the emissivity of tungsten, and a residual spectral correction function taking into account unknown factors of the lamp. The correction function was determined by measuring the spectra of a 1000 W, quartz-halogen, tungsten coiled filament (FEL) lamp at different temperatures.

Angled sidewalls in silicon slot waveguides: conformal filling and mode properties.

Effect of angled sidewalls on the filling and properties of silicon slot waveguides is discussed. We demonstrate complete filling of slot waveguide structures with oxide material systems using the atomic layer deposition technique and discuss use of various slot filling materials. Properties of the optical modes in angled-sidewall slot waveguides are studied.

Transients may occur in functional magnetic resonance imaging without physiological basis.

Functional magnetic resonance imaging (fMRI) has revolutionized the study of human brain activity, in both basic and clinical research. The commonly used blood oxygen level dependent (BOLD) signal in fMRI derives from changes in oxygen saturation of cerebral blood flow as a result of brain activity. Beyond the traditional spatial mapping of stimulus-activation correspondences, the detailed waveforms of BOLD responses are of high interest.

Degree of polarization in 3D optical fields generated from a partially polarized plane wave.

We show that, for 3D random electromagnetic fields that are created by optical systems from a partially polarized plane wave, two different definitions of the 3D degree of polarization proposed in literature have a monotonic one-to-one correspondence, thus providing the same information about the field's polarization state. Examples of 3D fields obeying this result are the evanescent wave generated in total internal reflection, the tightly focused beam, and the far field scattered from an electric point dipole.

Differences between partial polarizations in the space-time and space-frequency domains.

The time-domain degree of polarization of a stationary, random optical beam, in general, differs from that in the frequency domain. We elucidate the origin of their differences and consider several examples in which the two degrees of polarization either are or are not the same.

Dependence of resonant light transmission properties of a subwavelength slit on structural parameters.

We perform a systematic study of the resonant transmission of visible and near-infrared (NIR) light through a single subwavelength slit in a gold film when the parameters defining the structure are varied. We further examine the optical properties of a related nanostructure, a cross with subwavelength sized features. Focused ion beam (FIB) milling was used to fabricate nanoslits and crosses with linewidths ranging from 26 nm to 85 nm.

Comparison measurements of 0:45 radiance factor and goniometrically determined diffuse reflectance.

A comparison between the absolute gonioreflectometric scales at the Helsinki University of Technology (TKK) and the Physikalisch-Technische Bundesanstalt (PTB) has been accomplished. Six different reflection standards were measured for their 0:45 spectral radiance factor between 250 and 1650 nm in 10 nm intervals. Also, the 0:d reflectance factor between 400 and 1600 nm in 100 nm intervals was determined from goniometric reflectance measurements over polar angles with subsequent integration within the hemisphere above the sample.

Recursive multimodel partial least squares estimation of mineral flotation slurry contents using optical reflectance spectra.

In mineral flotation the X-ray fluorescence (XRF) grade measurements of the slurries typically give the most important on-line information on the state of the flotation process. It has been shown that the visual and near-infrared (VNIR) reflectance spectrum measurements of certain mineral slurries can be used to complete the sparse XRF slurry content information. This study focuses on the chemometrical analysis of the VNIR spectrum of the slurries and presents a new partial least squares (PLS)-based recursive multimodel approach with local orthogonal signal correction (OSC) for predicting the slurry contents.

Functional magnetic resonance imaging reference phantom.

Functional magnetic resonance imaging (fMRI) is widely used to pinpoint active brain areas. Changes in neuronal activity modulate the local blood oxygenation level, and the associated modulation of the magnetic field homogeneity can be detected with magnetic resonance imaging. Thus, the blood oxygenation level-dependent (BOLD) fMRI indirectly measures neuronal activity.

Determining the irradiance signal from an asymmetric source with directional detectors: application to calibrations of radiometers with diffusers.

The energy transfer integral between radiating rectangular and detecting circular parallel plates having nonideal angular characteristics is solved for modeling the distance dependence of the irradiance signal. The equation derived for the irradiance signal, which is called the modified inverse-square law, depends on the position, shape, size, and angular characteristics of the light source and the detector. We apply the new model equation to the calibration of a spectroradiometer to determine accurately the distance offsets, which fix the positions of the effective receiving apertures of diffusers used in the entrance optics of spectroradiometers.

Investigations on the humidity-induced transformations of salbutamol sulphate particles coated with L-leucine.

Purpose: The crystallization and structural integrity of micron-sized inhalable salbutamol sulphate particles coated with L-leucine by different methods are investigated at different humidities. The influence of the L-leucine coating on the crystallization of salbutamol sulphate beneath the coating layer is explored.

Methods: The coated particles are prepared by an aerosol flow reactor method, the formation of the L-leucine coating being controlled by the saturation conditions of the L-leucine.

Comparison of absolute spectral irradiance responsivity measurement techniques using wavelength-tunable lasers.

Independent methods for measuring the absolute spectral irradiance responsivity of detectors have been compared between the calibration facilities at two national metrology institutes, the Helsinki University of Technology (TKK), Finland, and the National Institute of Standards and Technology (NIST). The emphasis is on the comparison of two different techniques for generating a uniform irradiance at a reference plane using wavelength-tunable lasers. At TKK's Laser Scanning Facility (LSF) the irradiance is generated by raster scanning a single collimated laser beam, while at the NIST facility for Spectral Irradiance and Radiance Responsivity Calibrations with Uniform Sources (SIRCUS), lasers are introduced into integrating spheres to generate a uniform irradiance at a reference plane.

Arbitrarily short coherence length in wave fields within finite lossless source regions.

We show that it is possible to construct stochastic source distributions that generate wave fields with any desired spatial coherence properties inside a prescribed finite region, regardless of the refractive-index distribution therein. In particular, we demonstrate that there is no universal sinc-function form for the field correlations produced by statistically homogeneous and isotropic source distributions within large lossless regions, contrary to what is suggested by previous work. The results also disprove the commonly held belief that in lossless source regions the coherence length of the light is bounded below by the blackbody coherence length-that is, by approximately half the wavelength of the field.

Finite-element implementation for electron transport in nanostructures.

We have modeled transport properties of nanostructures using Green's-function method within the framework of the density-functional theory. The scheme is computationally demanding, so numerical methods have to be chosen carefully. A typical solution to the numerical burden is to use a special basis-function set, which is tailored to the problem in question, for example, the atomic-orbital basis.

Propagating and evanescent modes in two-dimensional wire media.

Electromagnetic waves in an artificial medium formed by two mutually orthogonal lattices of thin ideally conducting straight wires (referred to as a two-dimensional wire medium) are considered. An effective medium approach and a full-wave method based on the dyadic Green's function and the method of moments are developed. Effects of spatial dispersion, such as the appearance of anisotropy in a square lattice and an additional extraordinary wave, as in crystal optics, are demonstrated.