Binomial Attribute Sampling as an Aid in Defining a Representative Field of View in Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 466-467
Author(s):  
Evariste F. Osten
Keyword(s):  
Small Sample Size ◽  
Small Sample ◽  
Field Of View ◽  
Operating Parameters ◽  
Shape Factors ◽  
X Ray ◽  
Number Of Factors ◽  
Electron Microscopes ◽  
Representative Image ◽  
Selection Of

Statistical analyses are routinely applied to microscope data from micrographs (measurements, shape factors) and, using electron microscopes, from x-ray microanalytical systems (net counts, peak ratios). However selection of a field of view which is recorded on a micrograph and implied to be a representative image of the bulk of the sample (at that magnification) is done intuitively. Experienced microscopists do consider a number of factors in selecting and preparing a sample and then choose from many instrument operating parameters before they view the sample. At this point assuming that the best microscopy practice has been exercised there is still the problem of a great number of fields of view to select from. High magnifications exacerbate this selection problem: in an Ultra High Resolution Field Emission Scanning Electron Microscope sharp images of routine samples are easily obtained at magnifications of X100,000 - at this magnification, even with a small sample size (4mm × 7mm), there are 28 million mutually exclusive fields of view.

scholarly journals Fainter harder brighter softer: a correlation between αox, X-ray spectral state, and Eddington ratio in tidal disruption events

2020 ◽  
Vol 497 (1) ◽  
pp. L1-L6
Author(s):  
Thomas Wevers
Keyword(s):  
Small Sample Size ◽  
Galactic Nuclei ◽  
Small Sample ◽  
Tidal Disruption ◽  
X Ray ◽  
Relative Contribution ◽  
Positive Correlations ◽  
Optical Surveys ◽  
X Ray Binaries ◽  
Mass Functions

Abstract We explore the accretion states of tidal disruption events (TDEs) using a sample of seven X-ray bright sources. To this end, we estimate the relative contribution of the disc and corona to the observed X-ray emission through spectral modelling, and assess the X-ray brightness (through αox, L$_{2\ \rm keV}$, and fEdd,X) as a function of the Eddington ratio. We report strong positive correlations between αox and fEdd,bol; fEdd,X and fEdd,UV; and an anticorrelation for L$_{2\ \rm keV}$ and fEdd,UV. TDEs at high fEdd,bol have thermal dominated X-ray spectra and high (soft) αox, whereas those at low fEdd,bol show a significant power-law contribution and low (hard) αox. Similar to X-ray binaries and active galactic nuclei, the transition between X-ray spectral states occurs around fEdd,bol ≈ 0.03, although the uncertainty is large due to the small sample size. Our results suggest that X-ray surveys are more likely to discover TDEs at low fEdd,bol, whereas optical surveys are more sensitive to TDEs at high Eddington ratios. The X-ray and optical selected TDEs have different UV and X-ray properties, which should be taken into account when deriving rates, luminosity, and black hole mass functions.

scholarly journals Selection of Anti-Depressants in Geriatric Dermatoses- A Questionnaire Study of Dermatologists in Western Rajasthan, India

2021 ◽  
Vol 6 (1) ◽  
pp. 01-06
Author(s):  
Dilip Kachhawa ◽  
Hemamalini Narasimhan ◽  
Pankaj Rao
Keyword(s):  
Small Sample Size ◽  
The Elderly ◽  
Cross Sectional Study ◽  
Small Sample ◽  
Geriatric Population ◽  
Cross Sectional ◽  
Study Objective ◽  
Net Worth ◽  
Primary Disorder ◽  
Selection Of

Background: The Global Wealth Migration Review 2019 report, published by New World Wealth, estimated that 48% of India's total wealth was held by high-net worth individuals. Distinct factors dominate the prescription of anti-depressants in the geriatric population. Accordingly, the intention of pharmacotherapy in geriatric psycho dermatoses is deciphered in the study. . Objective: To survey and analyze the selection of anti-depressants by the dermatologists in the practice of geriatric pharmacotherapy. Methods: A questionnaire was designed and circulated among ninety-three dermatologists in three sessions and the data collected was analyzed through the cross-sectional study statistics. Results: The typical senior people attending the specialist were 25-50%. A sizeable familiarity of psycho cutaneous disturbance was attributed to dermatophyte infections, lichen simplex chronic, and Prurigo in descending order. The largely established primary disorder was neurotic excoriation. The prescription pattern was classified and 51.9% dermatologists are customary with psychotropic agent Doxepin over other agents. The discipline of the multidisciplinary approach was also studied. Limitation: Small sample size, uniregional study, prevalence study. Conclusions: The survey aids in evaluating mental health in cutaneous dermatoses of the elderly and assists the dermatologists to offer understated economical options and amend existing guidelines.

AFLPs in Pecan Genetics Research

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 527b-527
Author(s):  
L.J. Grauke ◽  
T.E. Thompson ◽  
A.S Reddy
Keyword(s):  
Fragment Length Polymorphism ◽  
Small Sample Size ◽  
Geographic Origin ◽  
Leaf Tissue ◽  
Genetic System ◽  
Small Sample ◽  
Scab Resistance ◽  
Genetics Research ◽  
Resistant Genotypes ◽  
Selection Of

Procedures were refined for extraction and amplification of DNA from pecan [Carya illinoinensis (Wangenh.) K. Koch] leaf tissue. Genomic DNA was extracted from leaf tissue from multiple inventories of `Wichita' and `Pawnee' and processed for Amplified Fragment Length Polymorphism (AFLPs). Using only four AFLP primers, 26 polymorphisms were identified, verifying the reproducibility and consistency of amplification. The application and limitation of the procedure for separating genotypes will be discussed. Twenty-four cultivars and seedlings representing the geographic range of the species were analyzed using 10 primer combinations. Despite the small sample size, polymorphic bands apparently associated with geographic origin were apparent. Individuals from selected controlled-cross families of the Pecan Breeding Program were bulked according to disease reaction and screened using 64 primers. Primary primers were selected on the basis of polymorphisms observed in bulked samples of resistant and susceptible genotypes. Eighteen primer combinations were selected for use on all individuals in the test. The candidate markers were evaluated to verify that parental lines were polymorphic for the trait, reducing to one the number of appropriate primers. That primer was used to screen 84 progeny samples phenotypically rated for disease resistance levels. The data were analyzed for linkage to scab resistance in the population. Factors limiting the utility of AFLPs as tools for selection of disease resistant genotypes, and their use in developing markers for heterodichogamy (a simple dominant genetic system) will also be discussed.

Medical Applications of a Small Sample X-Ray Fluorescence System

1975 ◽  
Vol 19 ◽  
pp. 497-510 ◽  
Author(s):  
A. C. Alfrey ◽  
L. L. Nunnelley ◽  
H. Rudolph ◽  
W. R. Smythe
Keyword(s):  
Small Sample Size ◽  
Small Sample ◽  
Medical Applications ◽  
X Ray ◽  
Sample Position ◽  
Computer Controlled ◽  
Analytical System ◽  
Compact Geometry ◽  
Tungsten Anode ◽  
Average Sample

A quantitative x-ray fluorescence (XRF) analytical system has been developed with the emphasis on small sample size. The system employs a two kilowatt tungsten anode x-ray tube, and an 80 mm2 lithium drifted silicon x-ray detector arranged in a compact geometry. Operation at 55 kV and 20 m A give a sensitivity of 153 counts/min/ng at Z=42 (molybdenum). A computer controlled target changer makes it capable of analyzing 32 targets automatically. The sample target is rotated during irradiation, so that the average sample position is defined to 0.2 mm. Several sets of 5 to 9 calibration targets have exhibited a standard deviation of less than 1%.

X-ray analysis of materials: Avoiding the pits and other practical hints

1994 ◽  
Vol 52 ◽  
pp. 380-381
Author(s):  
Alan Sandborg
Keyword(s):  
Good Deal ◽  
Operating Parameters ◽  
Simple Task ◽  
X Ray ◽  
Turn On ◽  
Optimum Parameters ◽  
Eds Analysis ◽  
Beam Sample ◽  
Detailed Nature ◽  
Selection Of

Introduction:EDS analysis of samples in a SEM or TEM is usually portrayed as a very simple process; just image your specimen, turn on the x-ray analyzer and all will be revealed about the chemistry of your sample. Unfortunately, that approach can be very misleading at best, and disastrous at worst. The analyst should get used to preparing himself for EDS x-ray analysis just like he or she does for any other process. A set of preparation steps should be followed until they become an unconscious method to be used before accepting the information coming from the EDS x-ray spectrum. After proper basic preparation, interpretation of the results and the selection of operating parameters is still very important due to the detailed nature of the specimen.Preparation:The most basic need is for the EDS system to be calibrated. This can be a difficult or simple task depending on the age of the system. Next, the basic geometry of the beam, sample and EDS detector needs to be considered. Before starting to analyze a specimen, the operator has probably put a good deal of effort into obtaining an optimum image. But the optimum parameters for imaging and x-ray analysis are rarely the same.

”When You’re in the Hospital, You’re in a Sort of Bubble.”

Crisis ◽  
2014 ◽  
Vol 35 (3) ◽  
pp. 154-160 ◽  
Author(s):  
Amanda Owen-Smith ◽  
Olive Bennewith ◽  
Jenny Donovan ◽  
Jonathan Evans ◽  
Keith Hawton ◽  
...  
Keyword(s):  
Lived Experience ◽  
Service Providers ◽  
Small Sample Size ◽  
Small Sample ◽  
Service Users ◽  
Number Of Factors ◽  
Increased Risk ◽  
Self Harm ◽  
The Uk ◽  
Depth Interviews

Background: Individuals are at a greatly increased risk of suicide and self-harm in the months following discharge from psychiatric hospital, yet little is known about the reasons for this. Aims: To investigate the lived experience of psychiatric discharge and explore service users’ experiences following discharge. Method: In-depth interviews were undertaken with recently discharged service users (n = 10) in the UK to explore attitudes to discharge and experiences since leaving hospital. Results: Informants had mixed attitudes to discharge, and those who had not felt adequately involved in discharge decisions, or disagreed with them, had experienced urges to self-harm since being discharged. Accounts revealed a number of factors that made the postdischarge period difficult; these included both the reemergence of stressors that existed prior to hospitalization and a number of stressors that were prompted or exacerbated by hospitalization. Conclusion: Although inferences that can be drawn from the study are limited by the small sample size, the results draw attention to a number of factors that could be investigated further to help explain the high risk of suicide and self-harm following psychiatric discharge. Findings emphasize the importance of adequate preparation for discharge and the maintenance of ongoing relationships with known service providers where possible.

Comparative analysis of XANES and EXAFS for local structural characterization of disordered metal oxides

2021 ◽  
Vol 28 (5) ◽  
Author(s):  
Junying Li ◽  
Yuanyuan Li ◽  
Prahlad K. Routh ◽  
Evgeniy Makagon ◽  
Igor Lubomirsky ◽  
...  
Keyword(s):  
Small Sample Size ◽  
Functional Materials ◽  
Local Environment ◽  
Structural Disorder ◽  
Active Species ◽  
Small Sample ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption ◽  
Xanes Analysis

In functional materials, the local environment around active species that may contain just a few nearest-neighboring atomic shells often changes in response to external conditions. Strong disorder in the local environment poses a challenge to commonly used extended X-ray absorption fine structure (EXAFS) analysis. Furthermore, the dilute concentrations of absorbing atoms, small sample size and the constraints of the experimental setup often limit the utility of EXAFS for structural analysis. X-ray absorption near-edge structure (XANES) has been established as a good alternative method to provide local electronic and geometric information of materials. The pre-edge region in the XANES spectra of metal compounds is a useful but relatively under-utilized resource of information of the chemical composition and structural disorder in nano-materials. This study explores two examples of materials in which the transition metal environment is either relatively symmetric or strongly asymmetric. In the former case, EXAFS results agree with those obtained from the pre-edge XANES analysis, whereas in the latter case they are in a seeming contradiction. The two observations are reconciled by revisiting the limitations of EXAFS in the case of a strong, asymmetric bond length disorder, expected for mixed-valence oxides, and emphasize the utility of the pre-edge XANES analysis for detecting local heterogeneities in structural and compositional motifs.

Production Control of Gold and Rhodium Plating Thickness on Very Small Samples by X-Ray Spectroscopy

1967 ◽  
Vol 11 ◽  
pp. 185-190
Author(s):  
George H. Glade
Keyword(s):  
Sample Size ◽  
Production Control ◽  
Control Method ◽  
Optical Measurement ◽  
Small Sample Size ◽  
Base Material ◽  
Small Sample ◽  
Optical Methods ◽  
Small Samples ◽  
X Ray

AbstractManufacture of reed switches, critical components in present-day dataprocessing support devices, requires a means of accurate, rapid analysis of elements used in plating tlie levers of the switch. Because of gready reduced feedback time, X-ray spectroscopy has replaced metallographic sectioning and optical measurement as a plating-thickness control method. While 6 hr were required to obtain thickness data for a given sample size by sectioning, X-ray spectroscopy requires only 2 hr, which permits better control of the plating operating. X-ray spectroscopy is now used routinely to control both gold and rhodium plating thicknesses in the 20- to 100μin. (1 × 10−6) thickness range. The large number of samples prevents long count duration, while the small sample size (0.110 by 0.033 in.) reduces the precision of the analysis. However, the precision of the X-ray and optical methods is approximately the same, 8% variance. X-ray accuracy is comparable to that of sectioning since the standards are obtained by sectioning. Simplicity of operation is required since relatively untrained operators are used. An aperture system is used to reduce background. The rhodium thickness measurement is obtained from gross rhodium intensity. Attenuation of gross nickel intensity from the base material was found to be a better measure of gold thickness intensity. Calibration for hoth gold and rhodium is performed by using the same wide detector conditions. The choice of analysis is made by changing only the 2θ angle, thus avoiding the time required for recalibration when changing analysis.

Variations in the Probe Beam Broadening with Operating Conditions in ESEM: Monte-Carlo Simulations and Edx Measurements

1997 ◽  
Vol 3 (S2) ◽  
pp. 1211-1212 ◽  
Author(s):  
I. C. Bache ◽  
S. Kitching ◽  
B. L. Thiel ◽  
A. M. Donald
Keyword(s):  
Probe Beam ◽  
Operating Conditions ◽  
Environmental Scanning ◽  
Operating Parameters ◽  
Critical Importance ◽  
X Ray ◽  
Computational Work ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Beam Broadening

An understanding of the scattering of an electron beam as it passes through a volume of low pressure gas is of critical importance for users of Low Vacuum and Environmental Scanning Electron Microscopes (LV-SEM & ESEM respectively) The ‘skirting’ of the primary beam as a result of scattering is of particular importance in X-ray microanalysis where scattered electrons, falling onto the sample away from the probe beam, can adversely affect the spatial resolution of the X-ray signal. A number of studies have attempted to quantify the width of the probe beam experimentally and hence determine optimum microscope operating parameters. Theoretical and computational work modelling the interactions of the beam with the gas have suggested that the shape of the probe beam can be modelled by some form of Gaussian. Experimental measurements, however, suggest that the probe has a skirted form rather than a Gaussian one.

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