scholarly journals Evolution of Brown Dwarf Atmospheres: Investigating Physical Parameters from Near-IR Spectra

2003 ◽  
Vol 211 ◽  
pp. 417-418
Author(s):  
Nadya Gorlova ◽  
Michael R. Meyer ◽  
Jim Liebert ◽  
George H. Rieke
Keyword(s):  
Ir Spectra ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Surface Gravity ◽  
Physical Parameters ◽  
Brown Dwarf ◽  
Near Ir ◽  
Near Infrared Spectra ◽  
Low Mass

We obtained near–infrared spectra of a sample of very low mass objects as a function of age in order to investigate the temperature and surface gravity sensitivity of several features in the J– and K–bands.

The near-infrared spectra of low-mass X-ray binaries and related objects

1991 ◽  
Vol 373 ◽  
pp. 228 ◽  
Author(s):  
A. P. Cowley ◽  
P. C. Schmidtke ◽  
D. Crampton ◽  
J. B. Hutchings ◽  
M. Bolte
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
X Ray ◽  
Near Infrared Spectra ◽  
Low Mass ◽  
X Ray Binaries

Efforts to Quantify Changes in Near-Infrared Spectra Caused by the Influence of Water, pH, Ionic Strength, and Differences in Physical State

1995 ◽  
Vol 49 (2) ◽  
pp. 181-187 ◽  
Author(s):  
James B. Reeves
Keyword(s):  
Amino Acids ◽  
Ionic Strength ◽  
Infrared Spectra ◽  
Physical State ◽  
Near Infrared ◽  
Near Ir ◽  
Near Infrared Spectra ◽  
Influence Of Water ◽  
Water Ph ◽  
Crystalline Sugars

The application of near-infrared spectroscopy to high-moisture samples has shown that the accuracy does not match that found for dried materials. The objective of this work was to attempt to quantify the effects of water, pH, ionic strength, and differences in physical state on near-infrared spectra with the use of model compounds. Spectra were compared by regression analysis of second derivatives after spectral subtraction of water. Spectra from 4900 to 4100 cm−1 at a resolution of 4 cm−1 were examined. Regression results showed spectra to be more similar among amorphous sugars and among dissolved sugars than among crystalline sugars. Also, spectra of amorphous sugars were statistically more similar to spectra of dissolved sugars than to spectra of crystalline sugars. While the spectra of one dissolved or amorphous sugar were statistically similar, this was not true for amino acids. Spectra of amorphous amino acids were similar to those of crystalline forms and neither were similar to those of dissolved forms. Spectrally, polymeric carbohydrates appeared very similar to one another when dry and behaved like amino acids when wet. Finally, efforts to directly relate these findings to near-IR spectroscopy calibration problems will require further research.

scholarly journals The NIRSPEC Brown Dwarf Spectroscopic Survey. I. Low‐Resolution Near‐Infrared Spectra

2003 ◽  
Vol 596 (1) ◽  
pp. 561-586 ◽  
Author(s):  
Ian S. McLean ◽  
Mark R. McGovern ◽  
Adam J. Burgasser ◽  
J. Davy Kirkpatrick ◽  
L. Prato ◽  
...  
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Brown Dwarf ◽  
Low Resolution ◽  
Near Infrared Spectra

Fuzzy Optimal Associative Memory for Background Prediction of Near-Infrared Spectra

1996 ◽  
Vol 50 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Busolo Wa Wabuyele ◽  
Peter De B. Harrington
Keyword(s):  
Associative Memory ◽  
Infrared Spectra ◽  
Plasma Glucose ◽  
Near Infrared ◽  
Second Derivative ◽  
Derivative Spectra ◽  
Near Ir ◽  
Near Infrared Spectra ◽  
Calibration Models ◽  
Second Derivative Spectra

A fuzzy optimal associative memory (FOAM) has been devised for background correction of near-infrared spectra. The FOAM yields improved predicted background scans for calculation of near-IR absorbance spectra of glucose in plasma matrices from single-beam data. The FOAM is an enhanced optimal associative memory (OAM) that uses a fuzzy function for encoding the spectra. The FOAM can predict a matching reference spectrum for a near-IR absorbance spectrum with low glucose absorbances by using second-derivative spectra. Glucose concentrations were predicted from calibration models furnished by partial least-squares (PLS). The FOAM stored reference spectra obtained from either water/phosphate buffer or plasma/glucose solutions. Both of these associative memories were evaluated. The standard error of prediction (SEP) for glucose concentration from an optimal PLS calibration model based on FOAM-corrected spectra was 0.60 mM for the water/phosphate buffer spectra. For FOAM-corrected spectra from plasma/glucose reference spectra, the SEP was 0.68 mM. The SEP of conventionally corrected double-beam second-derivative spectra was 0.81 mM. FOAM-corrected spectra generally furnish improved calibration models.

scholarly journals Physical parameters of T dwarfs derived from high-resolution near-infrared spectra

2009 ◽  
Vol 501 (3) ◽  
pp. 1059-1071 ◽  
Author(s):  
C. del Burgo ◽  
E. L. Martín ◽  
M. R. Zapatero Osorio ◽  
P. H. Hauschildt
Keyword(s):  
High Resolution ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Physical Parameters ◽  
Near Infrared Spectra

scholarly journals Effect of Dust Size on the Near-infrared Spectra (1.0–5.0 μm) of Brown Dwarf Atmospheres

2021 ◽  
Vol 919 (2) ◽  
pp. 117
Author(s):  
Satoko Sorahana ◽  
Hiroshi Kobayashi ◽  
Kyoko K. Tanaka
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Brown Dwarf ◽  
Near Infrared Spectra

scholarly journals Physical parameters of a sample of M dwarfs from high-resolution near-infrared spectra

2011 ◽  
Vol 16 ◽  
pp. 04006 ◽  
Author(s):  
C. del Burgo ◽  
R. Deshpande ◽  
E.L. Martín ◽  
M.R. Zapatero Osorio ◽  
S. Witte ◽  
...  
Keyword(s):  
High Resolution ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Physical Parameters ◽  
M Dwarfs ◽  
Near Infrared Spectra

Rapid Determining Contents of the Rhubarb Anthraquinones Compounds by Support Vector Machines Modeling based on Near Infrared Spectra

2020 ◽  
Vol 16 ◽  
Author(s):  
Linqi Liu ◽  
JInhua Luo ◽  
Chenxi Zhao ◽  
Bingxue Zhang ◽  
Wei Fan ◽  
...  
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Mean Squared Error ◽  
Rapid Determination ◽  
Partial Least Square ◽  
Least Square ◽  
Support Vector ◽  
Near Infrared Spectra ◽  
Aloe Emodin ◽  
Relative Differences

BACKGROUND: Measuring medicinal compounds to evaluate their quality and efficacy has been recognized as a useful approach in treatment. Rhubarb anthraquinones compounds (mainly including aloe-emodin, rhein, emodin, chrysophanol and physcion) are its main effective components as purgating drug. In the current Chinese Pharmacopoeia, the total anthraquinones content is designated as its quantitative quality and control index while the content of each compound has not been specified. METHODS: On the basis of forty rhubarb samples, the correlation models between the near infrared spectra and UPLC analysis data were constructed using support vector machine (SVM) and partial least square (PLS) methods according to Kennard and Stone algorithm for dividing the calibration/prediction datasets. Good models mean they have high correlation coefficients (R2) and low root mean squared error of prediction (RMSEP) values. RESULTS: The models constructed by SVM have much better performance than those by PLS methods. The SVM models have high R2 of 0.8951, 0.9738, 0.9849, 0.9779, 0.9411 and 0.9862 that correspond to aloe-emodin, rhein, emodin, chrysophanol, physcion and total anthraquinones contents, respectively. The corresponding RMSEPs are 0.3592, 0.4182, 0.4508, 0.7121, 0.8365 and 1.7910, respectively. 75% of the predicted results have relative differences being lower than 10%. As for rhein and total anthraquinones, all of the predicted results have relative differences being lower than 10%. CONCLUSION: The nonlinear models constructed by SVM showed good performances with predicted values close to the experimental values. This can perform the rapid determination of the main medicinal ingredients in rhubarb medicinal materials.

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