bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantification of Dental Microwear by Tandem Scanning Confocal Microscopy and Scale‐Sensitive Fractal Analyses
Authors: Ungar Peter S. , Brown Christopher A. , Bergstrom Torbjorn S. , Walker Alan 
Published: June 2010

AbstractDental microwear analysis is among the most commonly used approaches to reconstructing the diets of extinct animal species and past peoples. The usual procedure involves imaging tooth wear surfaces by scanning electron microscopy (SEM). Surfaces are characterized quantitatively by measurement of individual wear features (pits and scratches) on photomicrographs. Recent studies of living animals have shown associations between diets on one hand and patterns of dental microwear on the other. Furthermore, patterns on fossil teeth have been used to reconstruct diets in extinct forms. However, conventional methods for microwear analysis are limited. Scanning electron microscopy does not provide a true representation of these surfaces in three dimensions, and identification and measurement of individual features is time consuming, subjective, and subject to high interobserver error. This paper describes a new approach to the analysis of dental microwear using tandem scanning confocal microscopy and scale‐sensitive fractal analyses. The instrument used in this study provides three‐dimensional coordinates representing surfaces at a resolution equivalent to that employed by most SEM microwear studies. Fractal analyses offer objective, repeatable, quantitative characterization of surfaces. This approach eliminates major sources of error and increases power to resolve differences between species. Moreover, rapid surface characterization will allow examination of large samples to assess within species variation and to make finer distinctions between species.
Measurements of absolute X‐ray generation efficiency for selected K, L, and M‐lines
Authors: Prasad M. Satya , Joy D. C. 
Published: June 2010

AbstractThe absolute efficiency of generation of a selection of K, L, and M‐ x‐ray lines has been measured as a function of the incident electron beam energy. At an overvoltage U=2 this efficiency falls within the range 1E‐4 to 1E‐7, with K‐lines being highest and L‐Lines usually being the lowest. It is shown that for all three families of lines the efficiency has a functional variation which has the form A. (U‐1)n, as first suggested by Compton and Allison, where A and n are constants. Values of A and n for the K, L, and M shells are tabulated. The smoothly varying behavior of the efficiency makes it well suited for analytical use and spectrum simulation purposes.
Calibration and quantification of fast intracellular motion (FIM) in living cells using correlation analysis
Authors: Vesely Pavel , Mikš Antonín , Novík Jiří , Boyde Alan 
Published: June 2010

AbstractVideo rate confocal laser scanning microscopy at the highest spatial and temporal resolution of backscattered light (BSL) imaging allowed for regular observation of fast intracellular motion (FIM) first revealed in living neoplastic cells. However, the absence of an objective evaluation has hampered further study of the mechanisms and biological significance of FIM. Particularly, a quantification of apparent differences in velocities that would complement and improve the current demonstration of FIM by color coding using the combination of red‐green‐blue (RGB) images had been missing. Standard methods of tracking or pattern recognition could not be applied because of the fuzzy nature of images of FIM. A search for a suitable method led to correlation analysis. It was calibrated on Brownian motion and a known type of motion, such as cell marginal ruffling, compared with FIM. Results approved its explanatory potential. Therefore, several crucial incidences of FIM could be analyzed. Apart from an argument against viewing FIM as a manifestation of simple Brownian motion, the correlation analysis of FIM in the adjacent peripheries of a rat fibroblast and a K4 rat sarcoma cell confirmed the notion of higher and uneven distribution of velocity of FIM in a tumor cell so far shown in colorcoded images only. This result and other yet unpublished observations indicate that the velocity and topology of FIM can also contribute to a biological distinction between neoplastic and normal cells. Regular application of the correlation analysis should further expand the study of FIM for its mechanisms and predictive value. Such an approach should be thoroughly examined for a contribution to the knowledge of cancer cells.
A differentially pumped secondary electron detector for low‐vacuum scanning electron microscopy
Authors: Jacka M. , Zadrazil M. , Lopour F. 
Published: June 2010

AbstractA new design of secondary electron (SE) detector is described for use in low‐vacuum scanning electron microscopes. Its distinguishing feature is a separate detector chamber, which can be maintained at a pressure independent of the pressure in the specimen chamber. The two chambers are separated by a perforated membrane or mesh across which an electric field is applied, making it relatively transparent to low‐energy electrons but considerably less so to the gas molecules. The benefits of this arrangement are discussed. The final means of detecting the electrons can be a conventional scintillator and photomultiplier arrangement or any of the methods using the ambient gas as an amplifying medium. Images obtained with the detector show good SE contrast and low backscattered electron contribution.
Confocal microscopic image sequence compression using vector quantization and three‐dimensional pyramid
Authors: Cockshott W. Paul , Tao Yegang , Ao Gang , Balch Peter , Briones Ana M. , Daly Craig 
Published: June 2010

AbstractThe three‐dimensional (3‐D) pyramid compressor project at the University of Glasgow has developed a compressor for images obtained from confocal laser scanning microscopy (CLSM) device. The proposed method using a combination of image pyramid coder and vector quantization techniques has good performance at compressing confocal volume image data. An experiment was conducted on several kinds of CLSM data using the presented compressor compared with other well‐known volume data compressors, such as MPEG‐1.1 The results showed that the 3‐D pyramid compressor gave a higher subjective and objective image quality of reconstructed images at the same compression ratio, and presented more acceptable results when applying image processing filters on reconstructed images.
Three‐dimensional architecture of ribosomal DNA within Barley Nucleoli Revealed with Electron Microscopy
Authors: Iwano Megumi , Che Fang‐Sik , Takayama Seiji , Isogai Akira , Fukui Kiichi 
Published: June 2010

AbstractTo elucidate the topological positioning of ribosomal RNA genes (rDNA) and nucleolar structure in three dimensions, we examined the localization of rDNA using in situ hybridization (ISH) analysis by scanning electron microscopy (SEM). The rDNA genes within the three‐dimensional architecture of nucleoli were detected on chromatin fibers that connect a thick strand‐like structure and a protrusion of rDNA into the inner nuclear hole where the nucleolus is formed. This novel use of ISH together with SEM is useful for the analysis of nucleolar structure in detail. Furthermore, rDNA was detected at the periphery of the fibrillar centers (FCs) of the nucleolus using immuno‐gold labeling together with transmission electron microscopy (TEM). In situ hybridization with TEM confirmed that rDNA is naked and thus active in the FCs of nucleoli; ISH with SEM confirmed that rDNA is not covered with ribonucleo proteins at the protruding point and is thus inactive. We also show that the distribution pattern of FCs differs from sample to sample. These results indicate that rDNA is transcribed dynamically in a time‐ and region‐specific manner over the course of the cell cycle.
Ultrastructure changes induced by dry film formation of a trisodium phosphate blend, antimicrobial solution
Authors: Lea P. , Ding S.‐F. , Lemez S. B. 
Published: June 2010

AbstractTrisodium phosphate (TSP) has been reported to have antimicrobial activity and is approved by the U.S. Department of Agriculture for use in food processing applications. A novel (U.S. Patent 6,184,198), antimicrobial solution containing a blend of TSP, sodium bicarbonate, and sodium carbonate (TSP blend) has demonstrated effective inhibition of microbial contamination in a broad spectrum of applications. This high‐resolution cold field emission scanning electron microcopy (LVSEM) investigation details structural changes and dry film formation in various classes of microbes as a mechanism for antimicrobial activity of this solution. The results showed that this TSP blend solution completely inhibited the growth of pathogenic E. coli O157:H7, and Salmonella bacteria, the mold Cryptococcus, as well as a Norwalk virus surrogate‐feline calicivirus. Results by LVSEM confirmed that the antimicrobial effect was induced when encapsulating the target microbes in a high lubricity film that is formed around these organisms as the solution dries. The thickness of the film was estimated to be approximately 60 nm.
Measurement of total gas scattering cross‐section
Authors: He Jing , Joy David C. 
Published: June 2010

AbstractExperimental measurements are presented of the total scattering cross‐section of four gases: He, Air, CH4, and Argon as a function of electron beam energy. The method used was that of Gauvin. A comparison of theoretical estimates of the total scattering cross‐section with the experimental data indicates that the model used gives generally reliable results. The data confirm that the gases tend to be molecular rather than atomic in nature in this pressure range (1–300 Pascal). The factors affecting the accuracy of these results are examined.
Brush‐like fibers on the human chromosome periphery
Authors: Wen Guang Y. , Fisher Mariel B. , Genovese Marilyn , Goldberg Erick M. , Jenkins Edmund C. 
Published: June 2010

AbstractA brush‐like border apparently composed of fibers protruding from metaphase chromosomes of human lymphocytes was observed for the first time using transmission (TEM) and scanning electron microscopy (SEM). On the basis of size and sensitivity to colcemid, the fibers may be related to microtubules and spindle organization. The brush‐like fibers were observed when chemically fixed metaphase chromosome spreads were placed on glass slides and maintained under “wet” conditions (not allowed to air dry after fixation for conventional cytogenetic protocols) until postfixation protocols for TEM and SEM were performed. The purpose of this study was to establish the occurrence of the brush‐like fibers and to determine the effects of colcemid on these fibers.
Contrast at very low energies of the gold/carbon specimen for resolution testing
Authors: Müllerová Ilona , Frank Luděk 
Published: June 2010

AbstractThis paper concerns the problem of testing the image resolution in scanned electron micrographs, namely from the point of view of the image contrast for the standard gold/carbon test specimen within the full energy scale, down to eV units. Microscopes equipped with a cathode lens are considered and experimental results are presented for three devices differing in vacuum conditions and fields surrounding the specimen. At very low energies, the contrast is shown to either invert or disappear and this ambiguity is discussed and confronted with data simulated on the basis of measured electron yields from gold and carbon. It is concluded that the observations can be explained in terms of the surface cleanliness and strength of the surrounding fields.
A method for imaging single clay platelets by scanning electron microscopy
Authors: Rouse Jason H. , Ferguson Gregory S. , White Sara T. 
Published: June 2010

AbstractA method for preparing and observing clay platelets for size and shape analysis using scanning electron microscopy (SEM) was developed. Samples of the clay platelets were prepared by polyelectrolyte‐assisted adsorption onto a pyrolytic graphite surface. The use of graphite as a substrate was advantageous because of the low number of secondary electrons emitted from it during imaging by SEM. The resulting low background noise allowed the emission from the ∼1 nm thick clay sheets to be clearly visualized. Images of centrifuged montmorillonite showed large exfoliated platelets with lateral dimensions between 200 and 600 nm. In contrast, uncentrifuged montmorillonite appeared to contain a large amount of unexfoliated clusters. Although it was not possible to obtain high‐quality images of the smaller sheets of Laponite RD, the images of this material did contain size features comparable to the ∼30 nm2 size reported previously using light scattering, as well as transmission electron and atomic force microscopies.
Image signal‐to‐noise ratio estimation using the autoregressive model
Authors: Sim K. S. , Kamel Nidal S. 
Published: June 2010

AbstractIn the last two decades, a variety of techniques for signal‐to‐noise ratio (SNR) estimation in scanning electron microscope (SEM) images have been proposed. However, these techniques can be divided into two groups: first, SNR estimators of good accuracy, but based on impractical assumptions; second, estimators based on realistic assumptions but of poor accuracy. In this paper we propose the implementation of autoregressive (AR)‐model interpolation as a solution to the problem. Unlike others, the proposed technique is based on a single SEM image and offers the required accuracy and robustness in estimating SNR values.
A balanced technique for preparation of specimens from pathogenicity studies for scanning electron microscopy
Authors: Stadtländer Christian T. K.‐H. , Kirchhoff Helga 
Published: June 2010

AbstractThis paper reports our experiences with preparing delicate biological specimens for scanning electron microscopy. Three different washing methods were evaluated: One method allowed the analysis of the location of the bacterium Mycoplasma mobile on piscine gill epithelium and the optimal evaluation of histopathologic changes caused by this microbe. These results were achieved when specimens were washed three times in a cacodylic acid buffer after completion of the in vitro infection experiment in gill explant cultures. We also found that of three different concentrations of glutaraldehyde, a fixation with a 1.5% solution was sufficient to achieve excellent structural preservation, even without using post fixation in osmium tetroxide. Furthermore, this study showed that the use of acetone‐carbon dioxide in the critical point drying procedure resulted in well‐preserved piscine gill epithelium and mycoplasmas. Finally, long‐term storage of tissue specimens in 0.1 M cacodylic acid buffer is possible if the buffer is changed on a monthly basis to avoid growth of unwanted microorganisms, such as fungi.
A novel technique for visualizing electron beam induced charging
Authors: Tang Xiaohu , Joy David C. 
Published: June 2010

AbstractCharging is one of the most important problems encountered in scanning electron microscopy and as a result this phenomenon it has received a lot of both theoretical and experimental attention. Despite this, many questions remain about the nature and behavior of charging because of the limitations of the experimental techniques available to study it. For example, although it is now straightforward to determine in situ the surface potential of a sample that is charging during irradiation, it is difficult to measure the lateral extent of the charging, or its persistence once the incident beam is switched off. We describe here a simple technique which provides a rapid way of visualizing the temporal and spatial behavior of charging phenomena.
Scanning the pressure‐induced distortion of fingerprints
Authors: Mil'shtein S. , Doshi U. 
Published: June 2010

AbstractFingerprint recognition technology is an important part of criminal investigations it is the basis of some security systems and an important tool of government operations such as the Immigration and Naturalization Services, registration procedures in the Armed Forces, and so forth. After the tragic events of September 11, 2001, the importance of reliable fingerprint recognition technology became even more obvious. In the current study, pressure‐induced changes of distances between ridges of a fingerprint were measured. Using calibrated silicon pressure sensors we scanned the distribution of pressure across a finger pixel by pixel, and also generated maps of an average pressure distribution during fingerprinting. Emulating the fingerprinting procedure employed with widely used optical scanners, we found that on average the distance between ridges decreases by about 20% when a finger is positioned on a scanner. Controlled loading of a finger demonstrated that it is impossible to reproduce the same distribution of pressure across a given finger during repeated fingerprinting procedures.
Robust image signal‐to‐noise ratio estimation using mixed lagrange time delay estimation autoregressive model
Authors: Sim K. S. , Chuah H. T. , Cheng Zheng 
Published: June 2010

AbstractA new technique based on the statistical autoregressive (AR) model has recently been developed as a solution to signal‐to‐noise (SNR) estimation in scanning electron microscope (SEM) images. In the present study, we propose to cascade the Lagrange time delay (LTD) estimator with the AR model. We call this technique the mixed Lagrange time delay estimation autoregressive (MLTDEAR) model. In a few test cases involving different images, this model is found to present an optimum solution for SNR estimation problems under different noise environments. In addition, it requires only a small filter order and has no noticeable estimation bias. The performance of the proposed estimator is compared with three existing methods: simple method, first‐order linear interpolator, and AR‐based estimator over several images. The efficiency of the MLTDEAR estimator, being more robust with noise, is significantly greater than that of the other three methods.
Use of backscattered electron detector arrays for forming backscattered electron images in the scanning electron microscope
Authors: Wells O. C. , Gignac L. M. , Murray C. E. , Frye A. , Bruley J. 
Published: June 2010

AbstractThe backscattered electron (BSE) signal in the scanning electron microscope (SEM) can be used in two different ways. The first is to give a BSE image from an area that is defined by the scanning of the electron beam (EB) over the surface of the specimen. The second is to use an array of small BSE detectors to give an electron backscattering pattern (EBSP) with crystallographic information from a single point. It is also possible to utilize the EBSP detector and computer‐control system to give an image from an area on the specimen‐for example, to show the orientations of the grains in a polycrystalline sample (“grain orientation imaging”). Some further possibilities based on some other ways for analyzing the output from an EBSP detector array, are described.
Correction of logistic regression relative risk estimates and confidence intervals for systematic within‐person measurement error
Authors: Rosner B. , Willett W. C. , Spiegelman D. 
Published: June 2010

AbstractErrors in the measurement of exposure that are independent of disease status tend to bias relative risk estimates and other measures of effect in epidemiologic studies toward the null value. Two methods are provided to correct relative risk estimates obtained from logistic regression models for measurement errors in continuous exposures within cohort studies that may be due to either random (unbiased) within‐person variation or to systematic errors for individual subjects. These methods require a separate validation study to estimate the regression coefficient λ relating the surrogate measure to true exposure. In the linear approximation method, the true logistic regression coefficient β* is estimated by bT/λ, where β is the observed logistic regression coefficient based on the surrogate measure. In the likelihood approximation method, a second‐order Taylor series expansion is used to approximate the logistic function, enabling closed‐form likelihood estimation of β*. Confidence intervals for the corrected relative risks are provided that include a component representing error in the estimation of λ. Based on simulation studies, both methods perform well for true odds ratios up to 3·0; for higher odds ratios the likelihood approximation method was superior with respect to both bias and coverage probability. An example is provided based on data from a prospective study of dietary fat intake and risk of breast cancer and a validation study of the questionnaire used to asses dietary fat intake.
Skill and uncertainty in climate models
Authors: Hargreaves Julia C. 
Published: June 2010

AbstractAnalyses of skill are widely used for assessing weather predictions, but the time scale and lack of validation data mean that it is not generally possible to investigate the predictive skill of today's climate models on the multidecadal time scale. The predictions made with early climate models can, however, be analyzed, and here we show that one such forecast did have skill. It seems reasonable to expect that predictions based on today's more advanced models will be at least as skillful. In general, assessments of predictions based on today's climate models should use Bayesian methods, in which the inevitable subjective decisions are made explicit. For the AR4, the Intergovernmental Panel on Climate Change (IPCC) recommended the Bayesian paradigm for making estimates of uncertainty and probabilistic statements, and here we analyze the way in which uncertainty was actually addressed in the report. Analysis of the ensemble of general circulation models (GCMs) used in the last IPCC report suggests there is little evidence to support the popular notion that the multimodel ensemble is underdispersive, which would imply that the spread of the ensemble may be a reasonable starting point for estimating uncertainty. It is important that the field of uncertainty estimation is developed in order that the best use is made of current scientific knowledge in making predictions of future climate. At the same time, it is only by better understanding the processes and inclusion of these processes in the models, the best estimates of future climate will be closer to the truth. Copyright © 2010 John Wiley & Sons, Ltd.This article is categorized under:

Climate Models and Modeling > Knowledge Generation with Models