A new method for curve fitting to the data with low statistics not using the χ2-method

Awaya, Takashi

doi:10.1016/0029-554x(79)90287-8

Cited by 60 publications

(17 citation statements)

References 2 publications

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“…a , b , c and s are absolute amplitudes of the different components. The best fit was found minimizing the cost function proposed by Awaya [37] in order to minimize biases generated by the presence of data bins with low counts. The molecular fraction of quenched calcein ( f CA-Hb ) can be inferred by the following equation: …”

Section: Methodsmentioning

confidence: 99%

FRET Imaging of Hemoglobin Concentration in Plasmodium falciparum-Infected Red Cells

et al. 2008

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BackgroundDuring its intraerythrocytic asexual reproduction cycle Plasmodium falciparum consumes up to 80% of the host cell hemoglobin, in large excess over its metabolic needs. A model of the homeostasis of falciparum-infected red blood cells suggested an explanation based on the need to reduce the colloid-osmotic pressure within the host cell to prevent its premature lysis. Critical for this hypothesis was that the hemoglobin concentration within the host cell be progressively reduced from the trophozoite stage onwards.Methodology/Principal FindingsThe experiments reported here were designed to test this hypothesis by direct measurements of the hemoglobin concentration in live, infected red cells. We developed a novel, non-invasive method to quantify the hemoglobin concentration in single cells, based on Förster resonance energy transfer between hemoglobin molecules and the fluorophore calcein. Fluorescence lifetime imaging allowed the quantitative mapping of the hemoglobin concentration within the cells. The average fluorescence lifetimes of uninfected cohorts was 270±30 ps (mean±SD; N = 45). In the cytoplasm of infected cells the fluorescence lifetime of calcein ranged from 290±20 ps for cells with ring stage parasites to 590±13 ps and 1050±60 ps for cells with young trophozoites and late stage trophozoite/ early schizonts, respectively. This was equivalent to reductions in hemoglobin concentration spanning the range from 7.3 to 2.3 mM, in line with the model predictions. An unexpected ancillary finding was the existence of a microdomain under the host cell membrane with reduced calcein quenching by hemoglobin in cells with mature trophozoite stage parasites.Conclusions/SignificanceThe results support the predictions of the colloid-osmotic hypothesis and provide a better understanding of the homeostasis of malaria-infected red cells. In addition, they revealed the existence of a distinct peripheral microdomain in the host cell with limited access to hemoglobin molecules indicating the concentration of substantial amounts of parasite-exported material.

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Section: Methodsmentioning

confidence: 99%

FRET Imaging of Hemoglobin Concentration in Plasmodium falciparum-Infected Red Cells

et al. 2008

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“…In this paper, the statistical weights w i of Awaya (1979; w i ϭ f i Ϫ1 ) have been adopted as they are based on Poisson counting statistics, which typify trace element signals and yield more accurate peak areas at low counting statistics. As discussed in detail elsewhere (Ryan and Jamieson, 1993;Clayton and Ryan, 1990), the convergence of the least-squares fit is only weakly affected by the form of the weights, provided the approximation w i ϭ S i Ϫ1 is not used because it introduces errors at low counting statistics.…”

Section: Quantitative True Elemental Imagingmentioning

confidence: 99%

Quantitative trace element imaging using PIXE and the nuclear microprobe

Ryan

2000

Int J Imaging Syst Tech

364

229

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ABSTRACT:The X-ray spectra of pure elements, excited using MeV energy beam of protons from the nuclear microprobe, have known spectra signatures. This makes X-ray spectra for more complex mixtures amenable to decomposition into contributions from the component elements. By devising this procedure as a matrix operation that transforms directly from spectrum vector to elemental concentration vector, the decomposition can be performed very efficiently enabling the real-time projection of the component element signals. In the case of a raster-scanned beam, with data that contain position information for each X-ray event, this approach enables the real-time projection of component element spatial distribution images. This paper describes the matrix transform approach called dynamic analysis (DA), which enables on-line real-time imaging of major and trace elements using proton-induced X-ray emission (PIXE). The method also provides off-line iterative yield corrections to these images to compensate for changing sample composition across an image area. The resulting images are quantitative in two respects: (1) they resolve the pure element components and strongly reject interferences from other elements and (2) they can be directly interrogated for sample composition at each pixel, over areas, or along lines across the image area, with accuracy comparable to microanalytical point analysis methods. The paper describes the DA method, presents tests, and discusses its application to quantitative major and trace element imaging in geology.

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“…2 were obtained using the method of maximum likelihood as described by Awaya [24]. The well-known y -fitting method [25] was also used for comparison.…”

Section: Monte Carlomentioning

confidence: 99%

“…In addition, the chamber and its Ganges were constructed entirely of aluminum, which has a lower cross section for background (n, y) reactions than iron or copper [13]. The curves through the data are peak fits obtained using the maximum-likelihood method of Awaya [24]. The same peak shapes were used for gamma rays from 'H('He, y)'Li and 'H(d, y) He.…”

mentioning

confidence: 99%

Measurement of the cross-section ratioH3(d,γ)5
Kammeraad
¹
,
Hall
²
,
Sale
³

et al. 1993
Phys. Rev. C
34
0
11
0
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show abstract

A new method for curve fitting to the data with low statistics not using the χ2-method

Cited by 60 publications

References 2 publications

FRET Imaging of Hemoglobin Concentration in Plasmodium falciparum-Infected Red Cells

FRET Imaging of Hemoglobin Concentration in Plasmodium falciparum-Infected Red Cells

Quantitative trace element imaging using PIXE and the nuclear microprobe

Measurement of the cross-section ratioH3(d,γ)5
Kammeraad
¹
,
Hall
²
,
Sale
³

et al. 1993
Phys. Rev. C
34
0
11
0
View full text Add to dashboard Cite

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A new method for curve fitting to the data with low statistics not using the χ2-method

Cited by 60 publications

References 2 publications

FRET Imaging of Hemoglobin Concentration in Plasmodium falciparum-Infected Red Cells

FRET Imaging of Hemoglobin Concentration in Plasmodium falciparum-Infected Red Cells

Quantitative trace element imaging using PIXE and the nuclear microprobe

Measurement of the cross-section ratioH3(d,γ)5Kammeraad1, Hall2, Sale3 et al. 1993Phys. Rev. C340110View full textAdd to dashboardCite

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About

Measurement of the cross-section ratioH3(d,γ)5
Kammeraad
¹
,
Hall
²
,
Sale
³

et al. 1993
Phys. Rev. C
34
0
11
0
View full text Add to dashboard Cite