scholarly journals Spectral comparison of diffuse PAR irradiance under different tree and shrub shading conditions and in cloudy days

2018 ◽  
Vol 189 ◽  
pp. 274-282
Author(s):  
G. Gurrea-Ysasi ◽  
V. Blanca-Gimenez ◽  
I.C. Fita ◽  
A. Fita ◽  
J. Prohens ◽  
...  
Keyword(s):  
Spectral Comparison

scholarly journals Unsupervised Identification of Targeted Spectra Applying Rank1-NMF and FCC Algorithms in Long-Wave Hyperspectral Infrared Imagery

2021 ◽  
Vol 13 (11) ◽  
pp. 2125
Author(s):  
Bardia Yousefi ◽  
Clemente Ibarra-Castanedo ◽  
Martin Chamberland ◽  
Xavier P. V. Maldague ◽  
Georges Beaudoin
Keyword(s):  
Matched Filter ◽  
Principal Component ◽  
Hyperspectral Data ◽  
Clustering Methods ◽  
Spectral Angle Mapper ◽  
Long Wave ◽  
Clustering Approach ◽  
Spectral Comparison ◽  
Computational Simplicity ◽  
Mineral Identification

Clustering methods unequivocally show considerable influence on many recent algorithms and play an important role in hyperspectral data analysis. Here, we challenge the clustering for mineral identification using two different strategies in hyperspectral long wave infrared (LWIR, 7.7–11.8 μm). For that, we compare two algorithms to perform the mineral identification in a unique dataset. The first algorithm uses spectral comparison techniques for all the pixel-spectra and creates RGB false color composites (FCC). Then, a color based clustering is used to group the regions (called FCC-clustering). The second algorithm clusters all the pixel-spectra to directly group the spectra. Then, the first rank of non-negative matrix factorization (NMF) extracts the representative of each cluster and compares results with the spectral library of JPL/NASA. These techniques give the comparison values as features which convert into RGB-FCC as the results (called clustering rank1-NMF). We applied K-means as clustering approach, which can be modified in any other similar clustering approach. The results of the clustering-rank1-NMF algorithm indicate significant computational efficiency (more than 20 times faster than the previous approach) and promising performance for mineral identification having up to 75.8% and 84.8% average accuracies for FCC-clustering and clustering-rank1 NMF algorithms (using spectral angle mapper (SAM)), respectively. Furthermore, several spectral comparison techniques are used also such as adaptive matched subspace detector (AMSD), orthogonal subspace projection (OSP) algorithm, principal component analysis (PCA), local matched filter (PLMF), SAM, and normalized cross correlation (NCC) for both algorithms and most of them show a similar range in accuracy. However, SAM and NCC are preferred due to their computational simplicity. Our algorithms strive to identify eleven different mineral grains (biotite, diopside, epidote, goethite, kyanite, scheelite, smithsonite, tourmaline, pyrope, olivine, and quartz).

Antifungal Antibiotics from Calcarisporium thermophilum: A New Source of 15-Azahomosterol Derivatives

1990 ◽  
Vol 45 (3-4) ◽  
pp. 179-186 ◽  
Author(s):  
Paul Chrisp ◽  
Paul M. Dewick ◽  
F. Tom Boyle
Keyword(s):  
Antifungal Activity ◽  
Antifungal Metabolites ◽  
Ms Analysis ◽  
Antifungal Antibiotics ◽  
Spectral Comparison

Abstract Two antifungal metabolites isolated from Calcarisporium thermophilum were identified as 15-azahom osterols related to the compounds previously isolated from Geotrichum Jlavo-brun-neum. By full spectral comparison with authentic 15-aza-24-methylene-D-homocholesta-8,14-dien-3 β-ol (A 25822 B) from G. flavo-brunneum, the Calcarisporium metabolites were characterized as the 4a-m ethyl-and 4,4-dimethyl-analogues of A 25822 B. Several minor members of the series were also detected, and tentatively identified by MS analysis. The 15-azahom osterols exhibited good antifungal activity towards Candida parapsiliosis, though the activities were somewhat lower than that of the 4-demethyl derivative A 25822 B. Calcarisporium thermophi­lum is the second microorganism known to synthesize these unusual 15-azahomosterol deriva­tives.

scholarly journals MALDI-TOF MS protein fingerprinting of mixed samples

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Michael A Reeve ◽  
Denise Bachmann
Keyword(s):  
Analytical Techniques ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Flight Mass Spectrometry ◽  
Protein Fingerprinting ◽  
Large Databases ◽  
Spectral Comparison ◽  
Comparison Algorithms ◽  
Tof Ms

Abstract Analytical techniques currently available for the characterization of mixtures of microorganisms are generally based on next-generation sequencing. Motivated to develop practical and less-expensive methods for characterizing such mixtures, we propose, as an alternative or complement, the use of matrix-assisted laser-desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS), which is capable of high-resolution discrimination between species and even between biotypes within species. Potential approaches employing this technique for such characterization are discussed along with impediments to their successful employment. As a consequence, our rationale has been to capitalize on the powerful algorithms currently available for spectral comparison. Following this rationale, the first priority is to ensure the generation of MALDI-TOF MS spectra from mixtures of microorganisms that contain manageable peak complexities and that can be handled by the existing spectral comparison algorithms, preferably with the option to archive and re-run sample preparations and to pipette replicates of these onto MALDI-TOF MS sample plates. The second priority is to ensure that database entry is comparably facile to sample preparation so that large databases of known microorganism mixture MALDI-TOF MS spectra could be readily prepared for comparison with the spectra of unknown mixtures. In this article, we address the above priorities and generate illustrative MALDI-TOF MS spectra to demonstrate the utility of this approach. In addition, we investigate methods aimed at chemically modulating the peak complexity of the obtained MALDI-TOF MS spectra.

Examination of Count-Starved Gamma Spectra Using the Method of Spectral Comparison Ratios

2007 ◽  
Vol 54 (4) ◽  
pp. 1232-1238 ◽  
Author(s):  
David Michael Pfund ◽  
Robert C. Runkle ◽  
Kevin K. Anderson ◽  
Kenneth D. Jarman
Keyword(s):  
Spectral Comparison ◽  
Gamma Spectra

Spectral comparison of Dy, Tm and Dy/Tm in thermoluminescent dosimeters

1998 ◽  
Vol 31 (6) ◽  
pp. 754-765 ◽  
Author(s):  
T Karali ◽  
A P Rowlands ◽  
P D Townsend ◽  
M Prokic ◽  
J Olivares
Keyword(s):  
Thermoluminescent Dosimeters ◽  
Spectral Comparison

Spectral Comparison of Vertical and Horizontal Seismic Strong Ground Motions in Alluvial Basins

1998 ◽  
Vol 14 (4) ◽  
pp. 573-595 ◽  
Author(s):  
Rouben V. Amirbekian ◽  
Bruce A. Bolt
Keyword(s):  
High Frequency ◽  
Ground Motions ◽  
Frequency Content ◽  
S Waves ◽  
Anelastic Attenuation ◽  
Similar Distance ◽  
Vertical Ground ◽  
Spectral Comparison ◽  
Wave Conversion ◽  
Strong Ground

We analyze observations from the SMART2 array and the 1994 Northridge, California earthquake of spectral differences between vertical and horizontal strong seismic motions in alluvial basins. Our explanation is that the most energetic of such high-frequency vertical ground accelerations are generated by S-to-P seismic wave conversion within the transition zone between the underlying bedrock and the overlying sedimentary layers. The differences in combined scattering and anelastic attenuation for P and S waves lead to the observed spectral differences of the vertical motions between rock and deep alluvium sites. This model also accounts for the frequency content differences between the vertical and horizontal motions at sites in alluvial basins than at rock sites at similar distance ranges. The high-frequency cutoff of the acceleration power spectrum, fmax, is a useful comparison parameter. The results help in computing matched sets of synthetic ground motions above 2 Hz at alluvial sites.

Spectral Comparison of the Binding of Pyrene to β-Cyclodextrin and β-Cyclodextrin Derivatives

2000 ◽  
Vol 54 (4) ◽  
pp. 560-564 ◽  
Author(s):  
T. C. Werner ◽  
Kellie J. Forrestall ◽  
Sara L. McIntosh ◽  
Josef Pitha
Keyword(s):  
Hydrogen Bonds ◽  
Vibronic Band ◽  
Cyclodextrin Derivatives ◽  
Band Ratio ◽  
Oh Groups ◽  
Pyrene Fluorescence ◽  
Hydrophobic Cavity ◽  
Spectral Comparison ◽  
Complex Forms ◽  
Fluorinated Alcohol

β-Cyclodextrin (β-CD) is a seven-unit cyclic sugar molecule with a torroidal shape, a hydrophilic exterior, and a hydrophobic cavity. It has been hypothesized that pyrene (P) forms a P(β-CD)2 complex in which the pyrene lies in between the two wide, or secondary, rims of the two β-CDs. This dimer structure appears to be stabilized in the crystal state by hydrogen bonds between –OH groups on the rims of the adjacent β-CDs. We have chosen to test this hypothesis by comparing the fluorescence properties of pyrene in the presence of substituted β-CDs with these properties in the presence of β-CD. These properties include the shape (I/III vibronic band ratio) and lifetime of pyrene fluorescence and the effect on the pyrene I/III ratio of additives such as an iodide ion and a fluorinated alcohol. The CD derivatives in this investigation include those with no wide rim substitution and those with substitution on both the wide and narrow rims of β-CD. Our data indicate that the a P(β-CD)2 complex forms only when there is no substitution on the wide rim, which confirms the proposed structure for this complex.

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