Regularization method and applications in spectroscopy

Vucelic, M.; Mijovic, S.

doi:10.1016/0022-4073(96)00085-4

Cited by 8 publications

(3 citation statements)

References 3 publications

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“…Even though regularization methods for the robust solution of ill-posed problems have been available for some time 58 , their application in the life sciences has only recently become popular. In addition to the analysis of spectroscopic data 59 , more and more large data sets from genome research have been analyzed successfully, particularly in combination with machine learning 60 . The results presented here provide another successful application of the regularization method; in this case complex EPR spectra with multiple species could be analyzed; this approach may be applied to other systems that contain several overlapping high-spin ( S = 3/2, 5/2, ….)…”

Section: Discussionmentioning

confidence: 99%

Analysis of early intermediate states of the nitrogenase reaction by regularization of EPR spectra

Heidinger,

Perez,

Spatzal

et al. 2024

Nat Commun

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Due to the complexity of the catalytic FeMo cofactor site in nitrogenases that mediates the reduction of molecular nitrogen to ammonium, mechanistic details of this reaction remain under debate. In this study, selenium- and sulfur-incorporated FeMo cofactors of the catalytic MoFe protein component from Azotobacter vinelandii are prepared under turnover conditions and investigated by using different EPR methods. Complex signal patterns are observed in the continuous wave EPR spectra of selenium-incorporated samples, which are analyzed by Tikhonov regularization, a method that has not yet been applied to high spin systems of transition metal cofactors, and by an already established grid-of-error approach. Both methods yield similar probability distributions that reveal the presence of at least four other species with different electronic structures in addition to the ground state E0. Two of these species were preliminary assigned to hydrogenated E2 states. In addition, advanced pulsed-EPR experiments are utilized to verify the incorporation of sulfur and selenium into the FeMo cofactor, and to assign hyperfine couplings of 33S and 77Se that directly couple to the FeMo cluster. With this analysis, we report selenium incorporation under turnover conditions as a straightforward approach to stabilize and analyze early intermediate states of the FeMo cofactor.

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Section: Discussionmentioning

confidence: 99%

Analysis of early intermediate states of the nitrogenase reaction by regularization of EPR spectra

Heidinger,

Perez,

Spatzal

et al. 2024

Nat Commun

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“…This ill-posed problem should be regularized to make the computation of a meaningful approximate solution possible [7][8][9]. It refers to a process of introducing minimum additional infonnation about solution, such as restriction of smoothness, to get it to be stable.…”

Section: The Proceduresmentioning

confidence: 99%

Feature extraction from mammograms by using a'priory information

Mijovic

Daković

2013

2013 2nd Mediterranean Conference on Embedded Computing (MECO)

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The aim of X-ray imaging is to visualize the structure of body tissue with high spatial resolution and high contrast between different kinds of tissues. Early diagnosis of breast cancer requires almost a perfect imaging system or applying sophisticated post processing algorithms to 'clean' the image and extract needed information. Diagnostic images are often assessed in clinical practice by using subjective methods which are limited by the skill of the radiologist. A numerous computer-aided diagnosis (CAD) algorithms, that assist reviewers in their decisions and reduce the numbers of false positives, have been developed. However, these systems have not been well utilized yet and there are not the consensus among scientists and practitioners which are the most effective. Straightforward deconvolution of the image, using the known imperfectness of the imaging system, is not applicable due to non-avoidable noise. The noise makes these deconvolution procedures ill-posed from a mathematical point of view i.e., the solution is not stable and must be regularized. The level of regularization depends on an a' priory information about the image formation. A regularized deconvolution procedure, based on the knowledge of the noise estimation, is proposed for de-blurring mammograms and thus enhanced the features relevant for clinical outcomes. Testing its limitations is done as well. Promising preliminary results are obtained. Further investigations are needed to apply this procedure to a real mammographic unit.

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“…One of the methods to determine I(r) from integral relation Eq. 2 is Tikhonov regularization method [12]. This method requires minimum a priori information such as: the I(r) is a monotone positive function.…”

Section: Test and Calculation Of Radial Distributionmentioning

confidence: 99%

Radial distribution of hydrogen atoms in H 2 plasma

Mijovic¹,

Vuceljic²

2006

Open Physics

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The radial intensities of the H α and Hlines were used to obtain the radial distribution of hydrogen atoms in H 2 plasma discharge. We have obtained new equations in order to describe the distribution of atoms in molecule discharges. Abel's integral equation has been solved by Tikhonov's regularization procedure. Model functions have been introduced to examine the limitations in the applicability of this method. An estimation of the degree of dissociation in the radial direction has been obtained.

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Regularization method and applications in spectroscopy

Cited by 8 publications

References 3 publications

Analysis of early intermediate states of the nitrogenase reaction by regularization of EPR spectra

Analysis of early intermediate states of the nitrogenase reaction by regularization of EPR spectra

Feature extraction from mammograms by using a'priory information

Radial distribution of hydrogen atoms in H 2 plasma

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