Improvement of Stem Images by Means of Elimination of Influence of Statistical Fluctuation in Incident Electrons

1990 ◽  
Vol 48 (1) ◽  
pp. 184-185
Author(s):  
Hibino Michio ◽  
Takahiro Suzuki ◽  
Takaaki Hanai ◽  
Susumu Maruse
Keyword(s):  
Standard Deviation ◽  
Poisson Distribution ◽  
New Method ◽  
Statistical Fluctuation ◽  
Limit Set ◽  
Resolution Limit ◽  
Two Stages ◽  
Polynomial Distribution ◽  
Statistical Noise

The noise, due to statistical fluctuation of signal electrons, determines the ultimate resolution limit of imaging and analysis. The signal electrons (N) for each pixel are formed through two stages of statistical processes; Poisson distribution for the number of incident electrons (No) and polynomial distribution for forming signal electrons. The signal electrons therefore obey the Poisson distribution of average nOp (no:average of incident electrons, p:probability of forming signal electrons) and of standard deviation . In order to improve the resolution limit set by the statistical noise of signal electrons, a new method of normalization is proposed for STEM.In STEM imaging of thin specimens, the total transmitted electrons correspond to the incident electrons. It is therefore possible to know the incident electrons by summing up all the transmitted electrons and to normalize the signal electrons by incident electrons, for eliminating the influence of fluctuations of incident electrons. The average E and the standard deviation σ of normalized signal electrons are expressed by p and , respectively, for no> > 1 , indicating that E/σ value is improved by a factor of .

Compositional Analysis of III-V Interface Lattice Images

1980 ◽  
Vol 38 ◽  
pp. 318-319
Author(s):  
A. Olsen ◽  
J.C.H. Spence ◽  
P. Petroff
Keyword(s):  
Crystal Structure ◽  
Image Matching ◽  
Compositional Analysis ◽  
Depth Of Field ◽  
Limit Set ◽  
High Contrast ◽  
Resolution Limit ◽  
Fourier Image ◽  
Lattice Images ◽  
True Structure

Since the point resolution of the JEOL 200CX electron microscope is up = 2.6Å it is not possible to obtain a true structure image of any of the III-V or elemental semiconductors with this machine. Since the information resolution limit set by electronic instability (1) u0 = (2/πλΔ)½ = 1.4Å for Δ = 50Å, it is however possible to obtain, by choice of focus and thickness, clear lattice images both resembling (see figure 2(b)), and not resembling, the true crystal structure (see (2) for an example of a Fourier image which is structurally incorrect). The crucial difficulty in using the information between Up and u0 is the fractional accuracy with which Af and Cs must be determined, and these accuracies Δff/4Δf = (2λu2Δf)-1 and ΔCS/CS = (λ3u4Cs)-1 (for a π/4 phase change, Δff the Fourier image period) are strongly dependent on spatial frequency u. Note that ΔCs(up)/Cs ≈ 10%, independent of CS and λ. Note also that the number n of identical high contrast spurious Fourier images within the depth of field Δz = (αu)-1 (α beam divergence) decreases with increasing high voltage, since n = 2Δz/Δff = θ/α = λu/α (θ the scattering angle). Thus image matching becomes easier in semiconductors at higher voltage because there are fewer high contrast identical images in any focal series.

scholarly journals Characterizing Highly Benefited Patients in Randomized Clinical Trials

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Vivek Charu ◽  
Paul B. Rosenberg ◽  
Lon S. Schneider ◽  
Lea T. Drye ◽  
Lisa Rein ◽  
...  
Keyword(s):  
Randomized Clinical Trials ◽  
Controlled Trial ◽  
New Method ◽  
Usual Model ◽  
Randomized Controlled ◽  
Working Model ◽  
Large Numbers ◽  
High Benefit ◽  
Two Stages

AbstractPhysicians and patients may choose a certain treatment only if it is predicted to have a large effect for the profile of that patient. We consider randomized controlled trials in which the clinical goal is to identify as many patients as possible that can highly benefit from the treatment. This is challenging with large numbers of covariate profiles, first, because the theoretical, exact method is not feasible, and, second, because usual model-based methods typically give incorrect results. Better, more recent methods use a two-stage approach, where a first stage estimates a working model to produce a scalar predictor of the treatment effect for each covariate profile; and a second stage estimates empirically a high-benefit group based on the first-stage predictor. The problem with these methods is that each of the two stages is usually agnostic about the role of the other one in addressing the clinical goal. We propose a method that characterizes highly benefited patients by linking model estimation directly to the particular clinical goal. It is shown that the new method has the following two key properties in comparison with existing approaches: first, the meaning of the solution with regard to the clinical goal is the same, and second, the value of the solution is the best that can be achieved when using the working model as a predictor, even if that model is incorrect. In the Citalopram for Agitation in Alzheimer’s Disease (CitAD) randomized controlled trial, the new method identifies substantially larger groups of highly benefited patients, many of whom are missed by the standard method.

scholarly journals Alterações dimensionais em pastas de óxido de zinco/eugenol: um novo método para sua mensuração

2021 ◽  
pp. 39-55
Author(s):  
Léo Werner Süffert ◽  
Ennio Pessôa
Keyword(s):  
Standard Deviation ◽  
Personal Information ◽  
High Variability ◽  
Point Of View ◽  
New Method ◽  
Extensive Review ◽  
Review Of The Literature ◽  
Dimensional Changes ◽  
Impression Materials ◽  
Clinical Point

After an extensive review of the literature, regarding zinc.oxide/eugenol impression pastes, we selected 20 of the most representatives as our references. Trough personal information of several of the investigators it was discovered that dimensional changes of theese materials is one of the most difficult properties to be measured. A new method was developed to measure dimensional changes ot 4 (four) of the most widely used zinc.oxide/eugenol impression materials in Brazil. The results, presented through several graphs and tables showed that dimensional changes varied from 0,003%, values which may probably be considered negligible from a clinical point of view. We noticed, however, high values for standard deviation and variance which indicate the high variability within the experiments. Those values were not found when we used the same method with mercaptan and silicone impression materials, in which the measurement of dimensional changes was highly reproducible. One hypothesis (which we intend to investigate in a later research) is that, during storage, a sedimentation could occur, of the components of greater density! Consequently ther might result a change in composition, independent of the method used to establishe the proportion of the two pastes, be it by wheight or measurement of lenght, which could be the cause of variability of the composition of each mixture!

A Trial of Detecting Impending Access-graft Failure by Simplified Weekly Flow Monitoring

2005 ◽  
Vol 28 (3) ◽  
pp. 237-243 ◽  
Author(s):  
D. Vilkomerson ◽  
T. Chilipka ◽  
H. Rafi ◽  
P. Homel ◽  
G. Ghadari ◽  
...  
Keyword(s):  
Graft Failure ◽  
Controlled Trial ◽  
Effective Means ◽  
New Method ◽  
Control Group ◽  
Flow Monitoring ◽  
Monitoring Procedure ◽  
Two Stages ◽  
Induced Changes ◽  
Access Graft

Access graft failure is a major problem in hemodialysis. Monitoring the flow through the access so that impending failure can be detected and prevented seems reasonable, but recent clinical trials have failed to show any benefit of such monitoring. Described here are plans for a clinical trial of a new flow monitoring procedure that measures access flow weekly instead of monthly and, being performed before dialysis, avoids the dialysis-induced changes in graft flow that may have affected earlier trials. The planned trial is to be carried out in two stages, the first to establish the sensitivity and specificity of the new method, and the second (if the results of the first stage warrant it) a controlled trial comparing access-costs and hospitalization days between a monitored group and a matched standard care control group. It is hoped that this trial of the new method will establish it as an effective means of extending access-graft life.

A method of estimating intracranial decompensation in man

1976 ◽  
Vol 45 (2) ◽  
pp. 155-158 ◽  
Author(s):  
Jerzy Szewczykowski ◽  
Pawel Dytko ◽  
Adam Kunicki ◽  
Jolanta Korsak-Sliwka ◽  
Stanislaw Sliwka ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Intracranial Pressure ◽  
Characteristic Feature ◽  
Computer System ◽  
Monitoring System ◽  
New Method ◽  
Icp Monitoring ◽  
Content Type ◽  
On Line ◽  
Fine Print

✓ A new method of estimating intracranial decompensation in man is described. An on-line computer system is connected to an intracranial pressure (ICP) monitoring system to compute regression plots of mean ICP vs standard deviation; standard deviation is used as a measure of ICP instability. Two zones with distinctly different slopes are a characteristic feature of these plots. It is thought that the changes of slope signify intracranial decompensation.

Count Distribution and Precision in X-Ray Fluorescence Analysis

1959 ◽  
Vol 3 ◽  
pp. 95-107 ◽  
Author(s):  
Kurt F.J. Heinrich
Keyword(s):  
Standard Deviation ◽  
Poisson Distribution ◽  
Fluorescence Analysis ◽  
Experimental Results ◽  
X Ray ◽  
Statistical Fluctuations ◽  
Count Distribution ◽  
Analytical Result ◽  
Instrument Reliability

AbstractThe statistical fluctuations of photon counts arediscussedas a factor limiting the precision of the analytical result. Assuming a Poisson distribution, the theoretical standard deviation of the result can be calculated. While this prediction does not consider causes of variation other than the count statistics, it is useful in developing methods and checking instrument reliability. Practical examples using experimental results are given.

A Digital Mass Spectrometer

1971 ◽  
Vol 49 (8) ◽  
pp. 956-965 ◽  
Author(s):  
G. L. Cumming ◽  
M. D. Burke ◽  
F. Tsong ◽  
H. McCullough
Keyword(s):  
Time Series ◽  
Mass Spectrum ◽  
Standard Deviation ◽  
Mass Spectrometer ◽  
Magnetic Tape ◽  
Recording System ◽  
New Method ◽  
Digital Output ◽  
Similar Time ◽  
Spectral Content

A mass spectrometer control and recording system has been built which utilizes synchronous incremental stepping of the magnet current during the scanning of the mass spectrum with time-locked digitizing of the output, producing successive scans as similar time series and preserving the frequency spectral content of each scan. The digital output is recorded on magnetic tape and processed later on a computer. A new method of fitting polynomials to the reduced peak heights is described, which yields a measuring precision of about 0.06% at one standard deviation on 10–20 scans of the spectrum.Some studies of fractionation are described which illustrate the large errors which may occur from this effect.

Value of Scatter-Graphs for the Assessment of ECG Computer Measurement Results

1990 ◽  
Vol 29 (04) ◽  
pp. 413-423 ◽  
Author(s):  
P. Rubel ◽  
J. L. Willems ◽  
D. Morlet
Keyword(s):  
Standard Deviation ◽  
Performance Assessment ◽  
Gold Standard ◽  
Evaluation Method ◽  
New Method ◽  
Main Program ◽  
Measurement Study ◽  
Point Estimates ◽  
Computer Measurement ◽  
Measurement Results

AbstractA new method is presented, different from usual methods, for the discussion of the results of computer ECG measurement programs, based on a new graphical evaluation method. The proposed “scatter-graphs” both highlight the main program results and facilitate the comparison between various wave-recognition algorithms. They allow the distinction between the reliability of an algorithm, which is its capacity to provide a maximum of measurements with a minimum amount of errors, and its precision, i.e., the standard deviation of the differences between its point estimates and the reference.The method proves to be a powerful tool for the discussion of individual, as well as the median program results in CSE Measurement Study. It allows to highlight limitations induced in performance assessment by the variability of the reference itself, and to state that the median program is at least as close to the “Gold Standard” as the median of the referees.

Miura-Base Rigid Origami: Parametrizations of Curved-Crease Geometries

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Joseph M. Gattas ◽  
Zhong You
Keyword(s):  
Mechanical Performance ◽  
New Method ◽  
Additional Parameter ◽  
Matlab Toolbox ◽  
Subsequent Work ◽  
Folding Process ◽  
Two Stages

Curved-crease (CC) origami differs from prismatic, or straight-crease origami, in that the folded surface of the pattern is bent during the folding process. Limited studies on the mechanical performance of such geometries have been conducted, in part because of the difficulty in parametrizing and modeling the pattern geometry. This paper presents a new method for generating and parametrizing rigid-foldable, CC geometries from Miura-derivative prismatic base patterns. The two stages of the method, the ellipse creation stage and rigid subdivision stage, are first demonstrated on a Miura-base pattern to generate a CC Miura pattern. It is shown that a single additional parameter to that required for the straight-crease pattern is sufficient to completely define the CC variant. The process is then applied to tapered Miura, Arc, Arc-Miura, and piecewise patterns to generate CC variants of each. All parametrizations are validated by comparison with physical prototypes and compiled into a matlab Toolbox for subsequent work.

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