Correspondence Analysis Of Data Research Articles

Association between chemical properties of vineyard soils and occurrence of entomopathogenic fungi causing different levels of mortality in Planococcus ficus

Global demand for environmentally friendly grapevine cultivation and pest control has necessitated an improved understanding of the relationship between soil properties and beneficial, naturally occurring antagonists such as entomopathogenic fungi (EPF). Sixty six soil samples were collected from 22 vineyards in the Western Cape, South Africa. The association between soil nutrient status and EPF prevalence was examined. Fungi were isolated with methods of insect baiting and selective media. In addition, fungal isolates were tested against a key grapevine pest, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae). Pathogenicity of fungal strains against P. ficus was assessed with an immersion bioassay at a concentration of 1 × 108 conidia ml–1. Twenty-three fungal strains were isolated and correspondence analysis of data indicated a positive association between EPF (Metarhizium robertsii (Hypocreales: Clavicipitaceae) and Clonostachys rosea f. catenulata [Hypocreales: Bionectriaceae]) occurrence and optimum to high levels of soil-based macronutrients (C, N and Ca). Logistic regression revealed that K was positively correlated with M. robertsii (estimate = 0.03 ± 0.01; P < 0.05; odds ratio = 1.03). Strains of Beauvaria bassiana (Hypocreales: Cordycipitaceae) caused the highest mortalities (77.0 ± 2.0% to 87.0 ± 3.0%). This study showed that some soil nutrient properties corresponded to greater occurrence of EPF in grapevine soils.

Late Iron Age longhouse chronology. A study aimed at constructing a formal house chronology for the Late Iron Age, based on selected localities in central and eastern Jutland

This paper presents a formalised chronological study of the longhouses of the Late Iron Age. This is based on the correspondence analysis of data relating to house ground plans recorded at a number of Iron Age settlements in central and eastern Jutland, which, as a region, has the most comprehensive relevant data set, including many constructional details. The chronology constitutes a formalisation of the house-chronological considerations undertaken to date in reference to settlements in Jutland and results in a seriable sequence, the chronological significance of which is supported by stratigraphic observations. The study demonstrates that, in general, the investigated settlements follow the same chronological development and can therefore be correlated. Moreover, it shows that the placing of each individual house in the chronology is subject to some uncertainty, due to the relatively small number and long duration of the chronological features.

Toward an evidence-based taxonomy of everyday sounds

An organizing account of everyday sounds could greatly simplify the management of audio data. The job of an audio database manager will typically involve assigning a combination of textual descriptors to audio data, and perhaps allocation to a predefined category. Retrieval is likely achieved by matching the descriptor to keyword search terms or by browsing through categories. While classification of musical instruments using this type of approach is relatively simple by virtue of the fact that a predefined taxonomy can follow a signal-related hierarchy, non-musical sounds do not necessarily follow such a hierarchy. In addition, classification is made more problematic by the ambiguity of words used to describe everyday sounds. Another area in which the issue of establishing a taxonomy of everyday sounds is particularly pertinent is that of soundscape research; research into soundscapes—acoustic environments as they are perceived—is a relatively new and multidisciplinary area, and as such descriptive terms for everyday sounds are currently used inconsistently. Many existing attempts to taxonomize everyday sounds prescribe categories that are not mutually exclusive, in that everyday sounds could exist in a number of categories; moreover, many are not based on empirical evidence. Here, we present a robust method for creating an evidence-based taxonomy of everyday sounds, involving hierarchical clustering from dimensions generated by correspondence analysis of data from a simple card-sorting and naming procedure.

Effects of the Tillage Technology and the Forecrop on Weeds in Stands of Winter Wheat

The semipilot-scale field experiment was established in the cadastre of the village Letkovice in the South Moravian Region (Czech Republic). The study area was situated in a warm climatic region T2. Winter wheat was cultivated in two variants of tillage, viz. conventional tillage (CT) and minimum tillage (MT) and after three different forecrops (fodder beet, late potatoes, and broad (faba) bean). Weed infestation of wheat stands was evaluated in spring seasons of 2007 and 2008, always before the application of herbicides. Numbers of weed specimens and their species were defined by means of a calculation method. Recorded data were processed by means of multidimensional analyses of ecological data, viz. Data Correspondence Analysis (DCA) and Redundancy Analysis (RDA). Within the study period, altogether 22 weed species were identified in all variants with different tillage technologies and different forecrops. In the MT variant, the degree of winter wheat stand infestation with weeds was lower. As far as the forecrops were concerned, the most and the least intensive degrees of infestation were recorded on plots with faba bean and late potatoes, respectively.

French Ambiguities in Understandings of Corruption: Concurrent Definitions

Our research adds new empirical evidence to the debate about the ‘grey area’ of social understandings of corruption. Focusing on French citizens' ambiguities regarding the definition of political corruption we examine the notion of ‘greyness’ and identify the situations that give rise to controversies concerning the social definition of behaviour as ‘corrupt’. We examine the controversies that may arise from variation in the perception of behaviours as being normal or deviant, as well as from differences in evaluations (ranging from excusable to inexcusable) of their gravity. We argue that there are certain behaviours that people perceive as being deviant but not necessarily punishable because they are somehow consistent with their values and norms or belong to the category of ‘petty favouritism’ that have few harmful consequences for the public interest. The paper is based on a multiple correspondence analysis of data deriving from a nationally representative sample survey carried out in France in February 2006 on citizens' perceptions of professional politicians, public office holders and political corruption. The analysis reveals the existence of four types of representation, the first two of which (manifested by 50.5% of respondents) are coherent from a normative point of view while the other two types (manifested by 49.5% of respondents) are characterised by different forms of normative ambiguity.

Water geochemistry and sedimentary pigments in northern Victoria Land lakes, Antarctica

Total concentrations of algal pigments, organic C, C, N, P and S were determined in surface sediments from the littoral zone of 21 lakes in ice-free areas of northern Victoria Land (Antarctica) with different climatic and environmental conditions. Concentrations of major ions and nutrients were also determined in water samples from the same lakes. The latter samples had extremely variable chemical compositions; however, all the lakes resulted oligotrophic. Pigment concentrations in surface sediments were comparable to those reported for other Antarctic lakes and lower than those in oligotrophic lakes at lower latitudes. Cyanophyta, Chlorophyta and Bacillariophyta were the main taxa identified. These taxa correspond to those reported in previous microscopy-based studies on Antarctic phytoplankton and phytobenthos. Discriminant Function Analysis and Canonical Correspondence Analysis of data indicate that the distribution of pigments in these Victoria Land lakes depends mainly on their geographical location (particularly the distance from the sea) and nutrient status.

Invertebrate habitat use in relation to fetch and plant zonation in northern Lake Huron coastal wetlands

Northern Lake Huron marshes are among the most pristine wetlands in the Great Lakes. Almost 200 invertebrate taxa were collected from eight of these marshes from 1997 through 2001. Our objective was to explore relationships between wave exposure (fetch), plant community zones and invertebrate community composition using exploratory data analysis of invertebrate relative abundance. Effective fetch, an exposure measure which integrates fetch along three directions, ranged from 0.4 to 35.3 km. Invertebrates were collected with dip nets from wet meadow, Typha, and inner and outer Scirpus zones from 3 very protected (fetch &amp;lt;1 km), 3 protected (fetch 1–10 km) and 2 exposed (&amp;gt;10 km) marshes. Correspondence analyses of invertebrate relative abundance did not plot invertebrate communities of wet meadows along fetch gradients even though 7 of 30 common taxa were significantly (p &amp;lt; 0.05) correlated with fetch. After removing wet meadow data, correspondence analyses of data from remaining plant zones plotted marshes according to fetch with very protected and exposed sites at opposite ends of U-shaped gradients. Most taxa were generalists, occurred in marshes in all exposure categories, and plotted in the middle of correspondence analyses plots. Characteristic taxa plotting at the very protected end of the gradient included Gammarus, Crangonyx, Caecidotea, Chironomini, Tanytarsini, most Gastropoda and Sphaeriidae. Characteristic taxa plotting at the most exposed end included Sigara, Trichocorixa, Naididae (Stylaria), Tubificidae, and Bezzia. We present a conceptual model of potential changes in invertebrate community composition along gradients of wave exposure. In very protected marshes, organic sediments, detritus, and plant density are higher and dissolved oxygen is lower than in exposed marshes. Conditions are too harsh for some taxa found in very protected marshes.

Can Post-Oil Spill Patterns of Change be Used to Infer Recovery?

ABSTRACT Assessing recovery from oil spills in areas not previously studied must be based on comparisons of changes in affected areas to changes in unaffected areas. The present study on impacts and recovery in intertidal biological communities affected by the Exxon Valdez oil spill in Prince William Sound, Alaska, began after the spill. The study was designed to contrast recovery processes of two types of oiled stations: (1) stations that were treated with hot water delivered at high pressure to remove oil from the shorelines, and (2) untreated stations. Natural variation in species composition and abundance was concurrently monitored at unoiled stations. Correspondence analyses of data collected at rocky mid-intertidal stations from 1989 to 1997 show that unoiled algal assemblages remained relatively unchanged. Algal assemblages at treated and untreated oiled stations returned to patterns of species composition and abundance similar to those at unoiled stations. The convergence of patterns provides evidence of recovery. In contrast, changes in invertebrate abundances were characterized by high year-to-year variation that exceeded within year differences among oiled and unoiled stations. Convergence of patterns was not clearly evident in the analysis, and any recovery in the invertebrates can only be based on the fact that variations observed at the oiled stations appeared as great as natural variation. These results indicate that recovery for some species can be assessed when post-spill monitoring occurs for a sufficient length of time, but is also dependent on characteristics of the study design.

Petit-saut hydroelectric scheme: vegetal associations of stagnant waters in French Guyana

Hydroelectric plant of Petit Saut is under construction on the river Sinnamary in French Guyana. The future reservoir will flood a 300 km area of virgin forest. Under tropical climate as in Brazil or Surinam, the reservoirs are often overgrown with macrophyte vegetation during several years from the start of flooding operations. In order to assess the risks of vegetal proliferations in the future reservoir of Petit Saut, rnacrophyte lists have been made out with special attention to some prolific pecies (Eichhornia crassipes, Salvinia auriculata, Pistia stratiotes, Oxycariurn cubense, etc.) in all types of aquatic environments (marshes, ditches, canals, ricefields, etc) by using phytosociological method (abundance/dorninance indice). A correspondence analysis of data have permitted to show the relationships between specific vegetal communities and typical water environments. The spatial distribution of the macrophyte communities in these various environments according to their limnological features constitute a starting point for devising the mean to limit their proliferations.