Evaluating performance in three-dimensional fluorescence microscopy

In biological fluorescence microscopy, image contrast is often degraded by a high background arising from out of focus regions of the specimen. This background can be greatly reduced or eliminated by several modes of thick specimen microscopy, including techniques such as 3-D deconvolution and confocal. There has been a great deal of interest and some confusion about which of these methods is 'better', in principle or in practice. The motivation for the experiments reported here is to establish some rough guidelines for choosing the most appropriate method of microscopy for a given biological specimen. The approach is to compare the efficiency of photon collection, the image contrast and the signal-to-noise ratio achieved by the different methods at equivalent illumination, using a specimen in which the amount of out of focus background is adjustable over the range encountered with biological samples. We compared spot scanning confocal, spinning disk confocal and wide-field/deconvolution (WFD) microscopes and find that the ratio of out of focus background to in-focus signal can be used to predict which method of microscopy will provide the most useful image. We also find that the precision of measurements of net fluorescence yield is very much lower than expected for all modes of microscopy. Our analysis enabled a clear, quantitative delineation of the appropriate use of different imaging modes relative to the ratio of out-of-focus background to in-focus signal, and defines an upper limit to the useful range of the three most common modes of imaging.     

Utilization of integrated correlative light and electron microscopy (iCLEM) for imaging sedimentary organic matter

We report here a new microscopic technique for imaging and identifying sedimentary organic matter in geologic materials that combines inverted fluorescence microscopy with scanning electron microscopy and allows for sequential imaging of the same region of interest without transferring the sample between instruments. This integrated correlative light and electron microscopy technique is demonstrated with observations from an immature lacustrine oil shale from the Eocene Green River Mahogany Zone and mid‐oil window paralic shale from the Upper Cretaceous Tuscaloosa Group. This technique has the potential to allow for identification and characterization of organic matter in shale hydrocarbon reservoirs that is not possible using either light or electron microscopy alone, and may be applied to understanding the organic matter type and thermal regime in which organic nanoporosity forms, thereby reducing uncertainty in the estimation of undiscovered hydrocarbon resources.     

Optimal Pick-Up Locations for Irregular Concrete Panels

Aprocedure for minimization of principal stresses produced by initial lateral lifting of precast concrete structural panels is presented. An iterative approach using Powell's conjugate direction method searches for the nearly optimal pickup locations. A penalty function implemented with a nonsequential base takes into account side-constraint violations. A reasonably good initial guess for the design variables, which are coordinates of the pick-up locations, is essential. Accuracy of the results is dependent on the number of finite elements. The algorithm works well for a small number of design variables. A standard finite-element package is used for analysis on a microcomputer. Examples which demonstrate the procedure include a simply supported beam and several plates.     

Proof of the circle criterion for state space systems via quadratic Lyapunov functions — Part 2

In Part 1 of this paper a detailed analysis of the stability of a closed-loop system containing a single nonlinearity was made. The analysis is repeated here, but with stronger assumptions on the nonlinearity. The class of Total Derivative matrices is introduced and the role played by this class in generating quadratic Lyapunov functions for certain dynamical systems is considered. A new approach for deriving stability criteria is presented which is equivalent to the path integral method of Brockett.     

STUDY OF GLAZE AND BODY INTERFACE*

Lead-containing raw glazes were applied on biscuit tile and fired at cones 02, 2, and 4. The glaze body interface was examined microscopically by preparing thin cross sections. The powdered glassy portion was also investigated. Because the crystals separating at the interface were frequently too small for satisfactory study, a technique for promoting their growth was used. Anorthite, wollasto-nite, gehlenite, undissolved quartz, tridymite, and cristobalite were observed. The effects of altering the bases and the alumina and silica content of the glaze were studied, and the amount and the effect of the solution of the body were examined. The authors conclude that the interfacial layer is not necessarily intermediate in expansion conduct.     

PYRITE PARTICLE SIZE DISTRIBUTION AND PYRITIC SULFUR REDUCTION IN CRUSHED COALS: A PRELIMINARY REPORT

ABSTRACT

Six bituminous coals were ground to 28, 100, and 400 mesh x 0, and examined by optical automated image analysis (AIA) to estimate their pyrite particle size distributions and degree of liberation (DOL). These data were used to determine the feasibility of estimating specific-gravity-based pyritic sulfur reduction by AIA methods. Preliminary results indicate that further research is warranted. A review of the progress is presented.     

AN INTRODUCTION TO SUBQUANTUM KINETICS: II. An Open Systems Description of Particles and Fields

A nonlinear reaction-diffusion system, designated as Model G, is described. This system is similar to the Brusselator with the exception that it includes a third reaction intermediate, variable G. It is shown that a reaction-diffusion substrate of the kind specified by Model G is able to give rise to localized steady state concentration inhomogeneities which are autonomous and self-stabilizing and which exhibit many of the properties of subatomic particles. These “dissipative structures” generate substrate concentration gradients (fields) about themselves which serve as physically realistic analogs of gravitational and electrostatic potential fields. Test particles placed in these 1/r fields are found to experience a 1/r² accelerating force. Thus action-at-a-distance is elucidated, The same field giving rise to “electrostatic” effects is capable of causing closely spaced particles to undergo nuclear binding. Atom formation with electron orbital quantization is also predicted to occur. The fieid/source and wave/particle dualisms of classical field theory, as well as the field singularity problem, are avoided. It is predicted that gravitational mass, like electrostatic charge, manifests in two polarities, with the positive and negative mass states being correlated respectively with positive and negative charge