In vivo determination of local skin optical properties and photon path length by use of spatially resolved diffuse reflectance with applications in laser Doppler flowmetry

Methods for local photon path length and optical properties estimation, based on measured and simulated diffuse reflectance within 2 mm from the light source, are proposed and evaluated in vivo on Caucasian human skin. The accuracy of the methods was good (2%-7%) for path length and reduced scattering but poor for absorption estimation. Reduced scattering and absorption were systematically lower in the fingertip than in the forearm skin (633 nm). A maximum intrasite and interindividual variation of approximately 35% in an average photon path length was found. The methodology was applied in laser Doppler flowmetry, where path-length normalization of the estimated perfusion removed the optical property dependency.     

Numerical investigation of an electrochemically induced tagging in a nanospray for protein analysis

An on-line tagging of target species is simulated using the finite element method. A numerical model of an electrochemical EC(2X)E mechanism in a flow channel cell has been developed, corresponding to the electrochemical generation of a probe and the subsequent homogeneous reaction with the target. The kinetic and convective aspects are validated on short electrode geometries before taking into account the depletion of the target species. The model is then assessed according to previous experimental results on the on-line tagging of proteins. The occurrence and the efficiency of the on-line tagging are studied for both pressure-driven and electroosmotic flows. The involved phenomena including kinetic aspects are described in detail. Finally, optimal conditions for an effective quantitative tagging are discussed.     

Absolute refractive index determination by microinterferometric backscatter detection

Microinterferometric backscatter detection (MIBD) has previously been shown capable of measuring changes in the refractive index of liquids on the order of 10(-7). The MIBD technique is based on interference of laser light after it is reflected from different regions in a capillary. These reflections generate an interference pattern that moves upon changing refractive index of the liquid in the capillary. The small-angle interference pattern traditionally considered has a repetition frequency in the refractive index space that limits the ability to measure refractive index-to-refractive index changes causing such a repetition. Such refractive index changes are typically on the order of three decades. Recent modeling and experiments with the MIBD technique have shown that other intensity variations in the pattern are present for larger backscattered angles. By considering these variations, we have shown two methods by which it is possible to extend the dynamic measurement range to make an absolute refractive index measurement. One method utilizes variations in the Fresnel coefficients while the second approach is based on the refractive index-dependent onset of total internal reflection angles. With the second approach, we have been able to measure the absolute refractive index of a liquid with a precision of 2.5 x 10(-4).     

Pressure-viscosity coefficient of a refrigerant-oil mixture: Coefficient pression-viscositéd'un mélange frigorigène-huile

A coaxial cylinder viscosimeter has been used to determine the pressure-viscosity coefficient of a pure refrigeration oil and of a mixture of refrigerant and oil at gauge pressures up to 15 MPa. The test fluid, Gargoyle Arctic oil 300, is a naphthenic-base oil. The refrigerant was R22, chlorodifluoromethane, which is a commercially important refrigerant. In a gap apparatus the refrigerant-oil mixture has been visually inspected at different pressures. Two different mechanisms are involved in the refrigerant-oil mixture: the change in solubility with pressure and the change in viscosity with refrigerant concentration. If the mixture is pressurized with excess refrigerant available then the concentration of refrigerant will increase with increasing pressure and therefore the viscosity will decrease. If the concentration is kept at a constant level then the viscosity will increase with pressure. The results from the cylinder viscosimeter showed that the viscosity increase with pressure for the mixture was almost the same as for the pure oil.     

Energy resolution of a calorimetric charged-particle spectrometer

The energy resolution of a small diamond bolometer used as an energy-dispersive charged-particle detector has been calculated. Fluctuations in the amount of energy stored in lattice defects created through collision cascades constitute the main source, of broadening of the detector signals for most projectile types. In the present version of the detector, green-light fluorescence may also be an important noise source, but the fluorescence contribution may easily be removed by use of a very thin metal coating on the detector surface.     

Facilitation of receptivity in estrogen-primed rats during successive mating tests with progestins and methysergide.

Evaluated the role of hormonal and experiential variables in mediating the gradual increase of receptivity occurring during weekly tests in 142 Sprague-Dawley adult ovariectomized females. Hormone treatment consisted of estradiol benzoate (EB) injection followed by progesterone, 20alpha-hydroxyprogesterone, methysergide maleate, or oil during weekly mating tests. The experiential conditions were vaginal stimulation, mounts only, or no interaction with males. There was a gradual increase in receptivity in all groups even in the one receiving oil. Progressive facilitation occurred even when no interaction with the male was permitted. Interchanging the synergists on the 6th and 7th tests was not detrimental to the display of receptivity attained with synergists given previously. Thus, it is concluded that successive injections of EB rather than synergists or experience mediate this increase in receptivity. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transient load modeling: Markov on-off rectangular pulse processes

The class of Poisson renewal pulse processes has been widely accepted as a tool for modeling of transient load phenomena on structures. The paper focuses on a subclass with particular nice properties. It is the class of Markov on-off rectangular pulse processes. It contains both the Poisson square wave process and the compound Poisson process as special cases. Besides giving various time statistics the paper considers sums of independent and identically distributed Markov on-off rectangular pulse processes. Upper and lower bounds on the exceedance probability of any constant level are calculated. These results are compared with similar results for clipped normal processes also used in transient load modeling.     

Discrete event modeling of visually guided behaviors

When visual behaviors are combined to provide a specific functionality needed for a task, the combination is often based on heuristic rules. In this article we show that by adopting the Discrete-Event Systems (DES) formalism for describing the interaction between visual behaviors it is possible to provide systems that have well-defined properties in terms of observability and controllability. The method is in particular suited for describing the coupling between action and perception. An introduction to the use of DES is provided and it is demonstrated how DES are used for modeling behaviors and controlling a mobile robot equipped with a binocular camera head and some additional sensors.     

Model-driven vision for in-door navigation

For navigation in a partially known environment it is possible to provide a model that may be used for guidance in the navigation and as a basis for selective sensing. In this paper a navigation system for an autonomous mobile robot is presented. Both navigation and sensing is built around a graphics model, which enables prediction of the expected scene content. The model is used directly for prediction of line segments which, through matching, allow estimation of position and orientation. In addition, the model is used as a basis for a hierarchical stereo matching that enables dynamic updating of the model with unmodelled objects in the environment. For short-term path planning a set of reactive behaviours is used. The reactive behaviours include use of inverse perspective mapping for generation of occupancy grids, a sonar system and simple gaze holding for monitoring of dynamic obstacles. The full system and its component processes are described and initial experiments with the system are briefly outlined.