A jumping search algorithm is applied to achieve a broadband visible antireflection coating design for a wide-angular-incidence with an incident angle of up to 45 degrees from the normal. It is shown that the maximum ...
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A jumping search algorithm is applied to achieve a broadband visible antireflection coating design for a wide-angular-incidence with an incident angle of up to 45 degrees from the normal. It is shown that the maximum wide-angular visible spectral reflectance, obtained by different types of jumping search for a two-material 20-layer system, is reduced to less than 0.869% with 14-layer structures, and the maximum average visible spectral reflectance for incident angle lying in the range of 0-45 degrees is reduced to below 0.646%.
Thisis the second of two manuscripts describing how general linearmodeling (GLM) of a selection of the most abundant normalized fragmention abundances of replicate mass spectra from one laboratory can beused in conjun...
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Thisis the second of two manuscripts describing how general linearmodeling (GLM) of a selection of the most abundant normalized fragmention abundances of replicate mass spectra from one laboratory can beused in conjunction with binary classifiers to enable specific andselective identifications with reportable error rates of spectra fromother laboratories. Here, the proof-of-concept uses a training setof 128 replicate cocaine spectra from one crime laboratory as thebasis of GLM modeling. GLM models for the 20 most abundant fragmentsof cocaine were then applied to 175 additional test/validation cocainespectra collected in more than a dozen crime laboratories and 716known negative spectra, which included 10 spectra of three diastereomersof cocaine. Spectral similarity and dissimilarity between the measuredand predicted abundances were assessed using a variety of conventionalmeasures, including the mean absolute residual and NIST's spectralsimilarity score. For each spectral measure, GLM predictions werecompared to the traditional exemplar approach, which used the averageof the cocaine training set as the consensus spectrum for *** unsupervised models, EASI provided better than a 95% true positiverate for cocaine with a 0% false positive rate. A supervised binarylogistic regression model provided 100% accuracy and no errors usingEASI-predicted abundances of only four peaks at m/z 152, 198, 272, and 303. Regardless of the measureof spectral similarity, error rates for identifications using EASIwere superior to the traditional exemplar/consensus approach. As asupervised binary classifier, EASI was more reliable than using Mahalanobisdistances.
Thisstudy aims to resolve one of the longest-standing problemsin mass spectrometry, which is how to accurately identify an organicsubstance from its mass spectrum when a spectrum of the suspectedsubstance has not been...
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Thisstudy aims to resolve one of the longest-standing problemsin mass spectrometry, which is how to accurately identify an organicsubstance from its mass spectrum when a spectrum of the suspectedsubstance has not been analyzed contemporaneously on the same *** one of this two-part report describes how Rice-Ramsperger-Kassel-Marcus(RRKM) theory predicts that many branching ratios in replicate electron-ionizationmass spectra will provide approximately linear correlations when analysisconditions change within or between instruments. Here, proof-of-conceptgeneral linear modeling is based on the 20 most abundant fragmentsin a database of 128 training spectra of cocaine collected over 6months in an operational crime laboratory. The statistical validityof the approach is confirmed through both analysis of variance (ANOVA)of the regression models and assessment of the distributions of theresiduals of the models. General linear modeling models typicallyexplain more than 90% of the variance in normalized abundances. Whenthe linear models from the training set are applied to 175 additionalknown positive cocaine spectra from more than 20 different laboratories,the linear models enabled ion abundances to be predicted with an accuracyof <2% relative to the base peak, even though the measured abundancesvary by more than 30%. The same models were also applied to 716 knownnegative spectra, including the diastereomers of cocaine: allococaine,pseudococaine, and pseudoallococaine, and the residual errors werelarger for the known negatives than for known positives. The secondpart of the manuscript describes how general linear regression modelingcan serve as the basis for binary classification and reliable identificationof cocaine from its diastereomers and all other known negatives.
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