Principal Compo Research Articles

A Preliminary Research on the Development of the Hard X-ray Imaging Telescope

The hard X-ray imaging telescope based on the Fourier transform imaging technique is introduced. The double-layer parallel gratings are used to make the modulation and coding on the light emerging from a celestial X-ray source, the modulated light is acquired, to make the optoelectronic conversion by scintillation crystal detectors, and finally read out by the electronic system. The modulation collimator X-ray telescopes can be divided into two types: the spatial modulation and temporal modulation. The temporal modulation system requires the scanning motion of the detector system, but the spatial modulation system requires no motion. The technology of grating fabrication is investigated, and the basic structure design of the collimators is given. The principal compo- nents of the prototype hard X-ray imaging telescope of spatial modulation type are successfully developed, including the 8 CsI crystal detector modules (contain- ing photomultipliers or PMTs), 8-channel shaping amplifiers (two of them are prepared for experiments), and the data acquisition system. And the preliminary test results of the electronic system are also given.

A quantitative assessment of changes in seasonal potential predictability for the twentieth century

Changes over the twentieth century in seasonal mean potential predictability (PP) of global precipitation, 200 hPa height and land surface temperature are examined by using 100-member ensemble. The ensemble simulations have been conducted by using an intermediate complexity atmospheric general circulation model of the International Center for Theoretical Physics, Italy. Using the Hadley Centre sea surface temperature (SST) dataset on a 1 grid, two 31 year periods of 1920-1950 and 1970-2000 are separated to distinguish the periods of low and high SST variability, respectively. The standard deviation values averaged for the (''Nino-3.4''; 5S-5N, 170W-120W) region are 0.71 and 1.15 C, for the periods of low and high SST variability, respectively, with a percentage change of 62 % during December-January-February (DJF). The leading eigenvector and the associated principal compo- nent time series, also indicate that the amplitude of SST variations have positive trend since 1920s to recent years, particularly over the El Nino Southern Oscillation (ENSO) region. Our hypothesis states that the increase in SST variability has increased the PP for precipitation, 200 hPa height and land surface temperature during the DJF. The analysis of signal and noise shows that the signal-to-noise (S/N) ratio is much increased over most of the globe, particularly over the tropics and subtropics for DJF pre- cipitation. This occurs because of a larger increase in the signal and at the same time a reduction in the noise, over most of the tropical areas. For 200 hPa height, the S/N ratio over the Pacific North American (PNA) region is increas- ing more than that for the other extratropical regions, because of a larger percentage increase in the signal and only a small increase in noise. It is also found that the increase in seasonal mean transient signal over the PNA region is 50 %, while increase in the noise is only 12 %, during the high SST variability period, which indicates that the increase in signal is more than the noise. For DJF land surface temperature, the perfect model notion is utilized to confirm the changes in PP during the low and high SST variability periods. The correlation between the perfect model and the other members clearly reveal that the sea- sonal mean PP changed. In particular, the PP for the 31 years period of 1970-2000 is higher than that for the 31 years period of 1920-1950. The land surface tempera- ture PP is increased in northern and southern Africa, central Europe, southern South America, eastern United States and over Canada. The increase of the signal and hence the seasonal mean PP is coincides with an increase in tropical Pacific SST variability, particularly in the ENSO region.

A Novel Fault Identification Using WAMS/PMU

The important premise of the novel adaptive backup protection based on wide area information is to identify the fault in a real-time and on-line way. In this paper, the principal compo ...

Ciliate distributions and forcing factors in the Amundsen and Bellingshausen Seas (Antarctic)

Data for ciliate abundance, biomass and taxonomic composition, along with relevant biotic and abiotic parameters, were gathered from 9 profiles in the Bellingshausen and Amundsen Seas (Southern Ocean) during late summer and early autumn 2006. A total of 70 species were found, with extrapolations using species accumulation curves suggesting that the true diversity lay between 77 and 90 species. Ciliate abundance and biomass were low, but not unexpectedly so, given the time of year and productivity of the system. Despite the harsh environment, species richness was not less than that found for protists from more temperate habitats, and declined with depth less steeply than abundance and biomass. Ciliate biomass was driven primarily by productivity, with tighter correla- tions between chlorophyll a (chl a) and either abundance or biomass than those seen from other marine systems. Community composition was also driven by productivity, with a principal compo- nents analysis (PCA) on species data showing the first axis strongly correlated with productivity para- meters. Moreover, species abundance distributions (SADs) were most often best matched by the geo- metric distribution, thought to be expected when relatively few parameters determine species distributions. Abundance and diversity were also compared using settled and quantitative protargol stain (QPS) samples. QPS samples had lower mean abundance, higher total species richness and higher taxonomic resolution than did the settled samples. However, per-sample species (or morpho- type) richness was the same in settled and QPS samples.

An Approach to Face Recognition Based on Common Vector and 2DPCA

A novel approach to face recognition based on the common vector combined with 2-dimensional principal compo- nent analysis(2DPCA)is proposed in this paper.The common vector of one class is obtained by face images of the class pro- cessed by the Gram-Schrnidt orthogonalization to represent the common invariant properties of the class.Recognition results are obtained by 2DPCA procedure and distance test of the differ- ence vectors between the original image and the common vector of the class.Experiments are performed on ORL and Yale face databases and the results indicate that the proposed approach achieves good recognition results.

Wave exposure indices from digital coastlines and the prediction of rocky shore community structure

Topographical wave exposure indices allow objective assessment of the degree of wave action at coastal sites. We present a grid-based method for rapidly calculating indices at fine spatial resolutions along whole coastlines, and evaluate the power of candidate indices in predicting composi- tion of rocky shore communities. The method has 3 stages: (1) a grid is created from a vector-based digital coastline using geographical information systems (GIS) software; (2) for every coastal cell, wave fetch is determined as the distance to the nearest land cell in 16 angular sectors, using coarse-, medium- and fine-resolution searches of the surrounding cells up to a distance of 200 km; (3) wind energy (average wind speed and propor- tional occurrence) in each sector is calculated for nearby coastal sites. We calculated the average fetch in each sector ( F) and the sum of products of fetch and wind energy ( W) . A total of 57 species were surveyed at 185 sites in west Scotland for determination of trends with wave indices. Average wave fetch with a 200 m scale grid explained > 50% of the variation in the first principal compo- nent of the species-sites abundance matrix, with shore extent explaining another 10%. Incorporating wind data in the indices had a negligible effect on predictive power. Species diversity explained 61% of the variance in the second principal component and declined from low to high pelagic primary pro- ductivity. Separating direct physical effects from biological effects, such as food supply or grazing could potentially help us better understand the pro- cesses structuring biological communities on rocky shores.

Relationship Between Physiochemical Factors and Distribution of Stygobitic Crayfishes in Southeastern Caves

This study was conducted to determine the relationship between water chemistry and presence of stygobitic (cave-obligate) crayfishes (Cambaridae) in Tennessee, Alabama, and Georgia. We analyzed nine chemical factors in water samples from twenty caves, twelve of which contained stygobitic crayfish and eight in which none were found. A multiple analysis of variance using principal compo- nents scores suggested that absence of crayfish was associated with lower dissolved oxygen, higher ammonia, and higher water temperature. Caves with externally origi- nating streams supported no stygobitic crayfishes, and the chemical factors of the water in these caves were more variable.

Detection of Fecal Contamination on Cantaloupes Using Hyperspectral Fluorescence Imagery

ABSTRACTTo determine whether detection of fecal contamination on cantaloupes is possible using fluorescence imaging, hyperspectral images of cantaloupes artificially contaminated with a range of diluted bovine feces were acquired from 425 to 774 nm in responses to ultraviolet‐A (320 to 400 nm) excitation. Evaluation of images at emission peak wavelengths indicated that 675 nm exhibited the greatest contrast between feces contaminated and untreated surface areas. Two‐band ratios compared with the single‐band images enhanced the contrast between the feces contaminated spots and untreated cantaloupe surfaces. The 595/655‐nm, 655/520‐nm, and 555/655‐nm ratio images provided relatively high detection rates ranging from 79% to 96% across all feces dilutions. However, both single band and ratio methods showed a number of false positives caused by such features as scarred tissues on cantaloupes. Principal component analysis (PCA) was performed using the entire hyperspectral images data; 2nd and 5th principal component (PC) image exhibited differential responses between feces spots and false positives. The combined use of the 2 PC images demonstrated the detection of feces spots (for example, minimum level of 16‐μg/mL dry fecal matter) with minimal false positives. Based on the PC weighing coefficients, the dominant wavelengths were 465, 487, 531, 607, 643, and 688 nm. This research demonstrated the potential of multispectral‐based fluorescence imaging for online applications for detection of fecal contamination on cantaloupes.

The Baldwin Effect and Black Hole Accretion: A Spectral Principal Component Analysis of a Complete Quasar Sample

We have performed a spectral principal component analysis (SPCA) for an essentially complete sample of 22 low-redshift QSOs with spectral data from Lyto H� . SPCA yields a set of independent principal compo- nent spectra, each of which represents a set of relationships among QSO continuum and line properties. We find three significant principal components, which account for � 78% of the total intrinsic variance. The first component, carrying � 41% of the intrinsic variance, represents Baldwin relationships: anticorrelations between equivalent widths of broad emission lines and continuum luminosity. The narrow-line core (FWHM � 2000 km s � 1 ) of the broad emission lines dominate this component. The second component, accounting for � 23% of the intrinsic variance, represents the variations in UV continuum slope, which is probably the result of dust reddening, with possible contributions from starlight. The third principal component is directly related to the Boroson & Green '' eigenvector 1 '' (their first principal component), clearly showing the anti- correlation between strengths of optical Fe ii and (O iii) � 5007, and other relationships previously found in the H� -(O iii) region. This third component shows the expected strong correlation with soft X-ray spectral index. The widths of C iii) � 1909, Mg ii � 2798, and Balmer emission lines are also involved and clearly corre- lated, relating this component to black hole mass or Eddington accretion ratio. We find an inverse correlation between the strengths of the UV and optical Fe ii blends, as suggested by some photoionization models. We also find correlations of the strengths of several low-ionization UV lines with Fe ii(opt), and a strong positive correlation of C iv � 1549 with (O iii) strength. The wide wavelength coverage of our data enables us to see clearly the relationships between the UV and optical spectra of QSOs. The Baldwin effect and Boroson & Green's eigenvector 1 relationship are clearly independent. We demonstrate how Baldwin relationships can be derived using our first principal component, virtually eliminating the scatter caused by the third principal component. This rekindles the hope that the Baldwin relationships can be used for cosmological study. Subject headings: galaxies: active — galaxies: nuclei — quasars: emission lines — ultraviolet: galaxies

Spatial, seasonal and long-term fluctuations of plankton in relation to hydroclimatic features in the English Channel, Celtic Sea and Bay of Biscay

Plankton collected by the Continuous Plankton Recorder (CPR) survey were investigated for the English Channel, Celtic Sea and Bay of Biscay from 1979 to 1995. The main goal was to study the relationship between climate and plankton and to understand the factors influencing it. In order to take into account the spatial and temporal structure of biological data, a three-mode principal compo- nent analysis (PCA) was developed. It not only identified 5 zones characterised by their similar biolo- gical composition and by the seasonal and inter-annual evolution of the plankton, it also made species associations based on their location and year-to-year change. The studied species have stronger year- to-year fluctuations in abundance over the English Channel and Celtic Sea than the species offshore in the Bay of Biscay. The changes in abundance of plankton in the English Channel are negatively related to inter-annual changes of climatic conditions from December to March (North Atlantic Oscil- lation (NAO) index and air temperature). Thus, the negative relationship shown by Fromentin & Planque (1996; Mar Ecol Prog Ser 134: 11 1-1 18) between year-to-year changes of Calanus finmarchi- cus abundance in the northern North Atlantic and North Sea and NAO was also found for the most abundant copepods in the Channel. However, the hypothesis proposed to explain the plankton/NAO relationship is different for this region and a new hypothesis is proposed. In the Celtic Sea, a relation- ship between the planktomic assemblage and the air temperature was detected, but it is weaker than for the English Channel. No relationship was found for the Bay of Biscay. Thus, the local physical en- vironment and the biological composition of these zones appear to modify the relationship between winter climatic conditions and the year-to-year fluctuations of the studied planktonic species. This shows, therefore, that the relationship between climate and plankton is difficult to generalise.

Morphometrics, Homology, and Phylogenetics: Quantified Characters as Synapomorphies

It has been claimed that quantified features are inappropriate for phylogenetic anal- ysis. We consider that claim to be true under most conditions for characters discovered by com- monly used morphometric methods, including outline-based and conventional multivariate meth- ods. The most important reason these characters are unsuitable is that one of the tests of homol- ogy, the test of similarity, may be difficult to apply to them. This test is not even possible if the methods for comparing forms, such as outline-based techniques, do not ensure that the characters are located in the same part of the anatomy. Conventional methods, including principal compo- nents analysis, have no explicit basis for localizing characters. In addition, unless the transfor- mation between forms is homogeneous, conventional methods cannot dissect transformations re- gion by region to discover characters. However, one morphometric method, the thin-plate spline decomposed by its partial warps (TPS), finds characters that can be subjected to the same tests of homology (conjunction, similarity, and congruence) that we would apply to all other characters. Among available methods, TPS is unique in being able to locate the center and spatial extent of regional differences in shape and ensures that the same regions are compared among forms. We provide an example using the teleost fishes piranhas, in which tests of homology are applied to a found by the method. (Morphometrics; homology; synapomorphy; thin-plate spline; character analysis; piranha; Pygocentrus; Pygopristis; Serrasalmus.) Shape similarities among organisms Because much of our argument depends have long been recognized as having sys- on our meaning of homology, we begin tematic value. Whether shave features in with a brief foray into semantics. Follow- quantitative form can be a source of infor- ing a discussion of the definition of ho- mation about phylogenetic relationships is mology, we examine several morphometric more controversial. This doubt is reflected methods and judge their potential for in the literature, particularly in the claims yielding characters appropriate for phylo- that quantitative shape features cannot be genetic analyses. subjected to the same tests of homology that other characters must pass (Pimentel HOMOLOGY and Riggins, 1987). This position strikes di- Patterson (1982), like Rieppel (1980), dis- rectly at the use of morphometrics as a tinguished between taxic homology, a fea- class of tools for phylogenetic analysis. ture of a monophyletic group, and trans- Herein, we argue that ,at least one morpho- formational homology. The evidence of metric method is both suitable and useful taxic homologies is synapomorphies that in phylogenetic analysis because charac- have passed three tests: conjunction, simi- ters found by it can be treated in the same larity, and congruence. Systematists who way as can characters from any other use the term for shared source. However, we also contend that derived states, whether or not shown to be many methods currently in use are indeed congruent, qualify this definition by re- inappropriate because they cannot gener- stricting it to corroborated synapomor- ate results meeting the criteria applied to phies. Systematists who use terms such as phylogenetic characters. putative synapomorphy to refer to the coded characters prior to testing their con-

Cross-Validation of the WISC-R Factorial Structure Using Three-mode Principal Components Analysis and Perfect Congruence Analysis

By using three-mode principal components analysis and perfect congruence analysis in conjunction, the factorial structure of the 11 correlation matrices of the Wechsler Intelligence Scale for Children-Revised was analyzed within a single framework. This allows a unified description showing both the strong similarities between the standardization samples and some small differences related to age. Furthermore, claims about comparability between the WISC-R factorial structure, the structures of other independently conducted stud ies, and those of several translations of the WISC-R were evaluated. Again the overall similarity was strik ing, albeit most studies showed lower explained vari ances. Some age effects seemed to be present here as well. The contribution of three-mode principal compo nents analysis was found to lie primarily in the simul taneous analysis of the standardization samples, while perfect congruence analysis allowed the evaluation of the strengths and the correlations of the common WISC-R components in all studies without encountering rotation problems.

Three-Mode Principal Components Analysis of Semantic Differential Data: The Case of a Triple Personality

This paper shows how three-mode principal compo nents analysis can be useful for the analysis of seman tic differential ratings, in particular because no sum mation is necessary over any one mode. The use of "joint plots" (a variant of the biplot) and sums-of- squares interpretations is explained and illustrated.