Élaboration d'un coefficient de résistance au gui chez le chêne

1992 ◽  
Vol 70 (6) ◽  
pp. 1239-1246 ◽  
Author(s):  
E. B. Hariri ◽  
B. Jeune ◽  
S. Baudino ◽  
K. Urech ◽  
G. Sallé
Keyword(s):  
Quercus Robur ◽  
Quercus Rubra ◽  
Resistance Mechanism ◽  
Principal Component ◽  
Viscum Album ◽  
Quercus Petraea ◽  
Resistance Coefficient ◽  
Principal Component Analyses ◽  
Discriminant Analyses ◽  
Forest Managers

The reactions of oak to mistletoe (Viscum album L.) were studied using about 100 sensitive and susceptible oak twigs belonging to three species of oak: Quercus robur, Quercus rubra, and Quercus petraea. The main parameters likely to be involved in the resistance mechanism to mistletoe were measured on longitudinal radial sections. After conducting several principal component analyses and discriminant analyses, four variables were shown to have high discriminant values: thickness of the cortex, density of polyphenol-containing cells, thickness of the first layers of fibers, and thickness of collenchyma. Statistical analyses were performed using a large number of samples to define a discriminating function linking the four variables and to propose a resistance coefficient. The significance of such a coefficient for forest managers and pharmacologists is discussed in relation to their own needs. Key words: Viscum album, Quercus, resistance coefficient, mistletoe.

Geographic variation of the Anderson’s Niviventer (Niviventer andersoni) (Thomas, 1911) (Rodentia: Muridae) of two new subspecies in China verified with cranial morphometric variables and pelage characteristics

Zootaxa ◽  
2009 ◽  
Vol 2196 (1) ◽  
pp. 48-58 ◽  
Author(s):  
SONG LI ◽  
JUNXING YANG
Keyword(s):  
Geographic Variation ◽  
Yunnan Province ◽  
Principal Component ◽  
Taxonomic Revision ◽  
Western Yunnan ◽  
Principal Component Analyses ◽  
Discriminant Analyses ◽  
Southern Shaanxi ◽  
First Time ◽  
Northwestern Yunnan

A total of 66 specimens of Niviventer andersoni with intact skulls was investigated on pelage characteristics and cranial morphometric variables. The data were subjected to principal component analyses as well as to discriminant analyses, and measurement overlap was studied as compared with the coefficient of difference. The results indicate that three subspecies of N. andersoni can be recognized in China, including N. a. andersoni broadly distributed from northwestern Yunnan, Sichuan, northward to southern Shaanxi, and eastward to Hubei, N. a. pianmaensis subsp. nov. in western Yunnan, and N. a. ailaoshanensis subsp. nov. in Mt. Ailaoshan, central Yunnan province. Our study for the first time validates its subspecies differentiation that is most likely related to intra-specific geographic variation. In addition, a taxonomic revision of Niviventer andersoni in China is described.

Analysis of variation in the Elaphrus americanus complex of North America (Coleoptera: Carabidae)

1981 ◽  
Vol 59 (12) ◽  
pp. 2253-2274 ◽  
Author(s):  
Henri Goulet ◽  
Bernard R. Baum
Keyword(s):  
North America ◽  
Univariate Analysis ◽  
Principal Component ◽  
Evolutionary Significance ◽  
Mahalanobis Distances ◽  
Taxonomic Analysis ◽  
Principal Component Analyses ◽  
Discriminant Analyses ◽  
Euclidean Distances ◽  
Analysis Of Variation

Elaphrus americanus Dejean (sensu Lindroth, 1961) is a complex of two nearctic species: E. americanus and E. finitimus Casey. This study is primarily devoted to E. americanus, which includes two subspecies: a boreal subspecies and a newly described western subspecies, E. americanus sylvanus Goulet n. subsp., for which the type locality is Oregon, Coos Co., 16 miles north of Powers.The species and subspecies mentioned above were recognized by means of numerical taxonomic analysis. Most intuitively acceptable were the results of phenetic clustering of Mahalanobis distances followed by a series of discriminant analyses. Various analyses were carried out based directly on computed euclidean distances, e.g. principal coordinate analyses, nonmetric multidimensional scaling, and still others by computing first the variance–covariance matrix, e.g., principal component analyses. Other geographically distinct populations were recognized by univariate analysis of nominal characters.Phylogenetic relationships between various populations of E. americanus are partly reconstructed. A reconstruction of past distribution of these populations is presented and their evolutionary significance discussed.

The variation of angles between anterior and posterior carinae of tyrannosaurid teeth

2012 ◽  
Vol 49 (3) ◽  
pp. 477-491 ◽  
Author(s):  
Miriam Reichel
Keyword(s):  
Strong Correlation ◽  
Multivariate Analyses ◽  
Principal Component ◽  
Tooth Size ◽  
Data Set ◽  
In Situ Data ◽  
Principal Component Analyses ◽  
Canonical Variates ◽  
Discriminant Analyses

Tyrannosaurid tooth measurements have been shown to be a powerful tool for systematic analyses, as well as for studies on function and evolution of theropod dentition. In this analysis, a variable not previously addressed in depth is added to the tyrannosaurid data set. The angle between the anterior and posterior carinae can be difficult to measure consistently and a method is hereby proposed through the use of a digitizer. Five tyrannosaurid genera were analyzed: Tyrannosaurus , Tarbosaurus , Albertosaurus , Daspletosaurus , and Gorgosaurus . Only in situ data were used, and therefore some of the taxa had a limited amount of information available for this analysis. The measurements were analyzed through multivariate analyses using Paleontological Statistics (PAST), version 2.06. The analyses included principal component analyses (PCAs), discriminant analyses (DAs), and canonical variates analyses (CVAs). The results of these analyses revealed that the angle between carinae contributes significantly to the variation in the tyrannosaurid tooth data set. Additionally, this variable showed a strong correlation to tooth function (and, consequently, to tooth families), rather than tooth size. The variation observed between taxa at this stage seems insufficient for systematic purposes, however additional in situ data would help improve the effectiveness of this tool.

scholarly journals Fast diffusion kurtosis mapping of human brain at 7 Tesla with hybrid principal component analyses

IEEE Access ◽  
2021 ◽  
pp. 1-1
Author(s):  
Fangrong Zong ◽  
Jiaxin Du ◽  
Xiaofeng Deng ◽  
Xubin Chai ◽  
Yan Zhuo ◽  
...  
Keyword(s):  
Human Brain ◽  
Principal Component ◽  
7 Tesla ◽  
Fast Diffusion ◽  
Principal Component Analyses ◽  
Diffusion Kurtosis
Sign in / Sign up

Export Citation Format

Share Document