scholarly journals Ecological Regulation of Black Leaf Streak Disease Driven by Plant Richness in Banana Agroecosystems

2018 ◽  
Vol 108 (10) ◽  
pp. 1184-1195 ◽  
Author(s):  
Charlotte Poeydebat ◽  
Dominique Carval ◽  
Philippe Tixier ◽  
Marie-Odette Daribo ◽  
Luc De Lapeyre De Bellaire
Keyword(s):  
Plant Diversity ◽  
Incubation Time ◽  
Structural Equation ◽  
Equation Modeling ◽  
Canopy Openness ◽  
Field Scale ◽  
Plant Richness ◽  
Spore Abundance ◽  
Black Leaf Streak ◽  
Black Leaf Streak Disease

Black leaf streak disease (BLSD), caused by the fungus Mycosphaerella fijiensis, is an important threat to banana production. Although its control relies on costly and unsustainable use of fungicides, ecological regulation of BLSD linked to field-scale plant diversity has received little attention. We monitored banana phytometers in plots in banana-based fields where no fungicides were applied. Within each plot, we measured plant richness in three strata, canopy openness, necrotic leaf removal, Musa abundance and richness. We quantified ecological regulation of five BLSD parameters (inoculum sources, spore abundance, lesion density, incubation time, and the area under the disease progression curve) and identified, using structural equation modeling, the characteristics of the plant community and the mechanisms likely responsible for the regulation. Regulation occurred, but most effectively before lesion formation, and was mainly related to plant richness between 1.5 and 5m high. A barrier effect, rather than a dilution effect, more likely limited spore abundance. Our results support the hypothesis that the potential effects of plant richness on leaf-scale microclimate variability and on the diversity of epiphyllic microorganisms are involved in the regulation of incubation time and lesion density. Field-scale management of plant diversity may be a promising lever to foster ecological regulation of BLSD.

scholarly journals Indirect drivers of plant diversity-productivity relationship in semiarid sandy grasslands

2012 ◽  
Vol 9 (4) ◽  
pp. 1277-1289 ◽  
Author(s):  
X. A. Zuo ◽  
J. M. H. Knops ◽  
X. Y. Zhao ◽  
H. L. Zhao ◽  
T. H. Zhang ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Plant Diversity ◽  
Structural Equation ◽  
Environmental Gradients ◽  
Northern China ◽  
Equation Modeling ◽  
Vegetation Composition ◽  
Wet Meadow ◽  
Positive Correlation ◽  
Sandy Grasslands

Abstract. Although patterns between plant diversity and ecosystem productivity have been much studied, a consistent relationship has not yet emerged. Differing patterns between plant diversity and productivity have been observed in response to spatial variability of environmental factors and vegetation composition. In this study, we measured vegetation cover, plant diversity, productivity, soil properties and site characteristics along an environmental gradient (mobile dune, semi-fixed dune, fixed dune, dry meadow, wet meadow and flood plain grasslands) of natural sandy grasslands in semiarid areas of northern China. We used multivariate analysis to examine the relationships between environmental factors, vegetation composition, plant diversity and productivity. We found a positive correlation between plant diversity and productivity. Vegetation composition aggregated by the ordination technique of non-metric multidimensional scaling had also a significantly positive correlation with plant diversity and productivity. Environmental gradients in relation to soil and topography affected the distribution patterns of vegetation composition, species diversity and productivity. However, environmental gradients were a better determinant of vegetation composition and productivity than of plant diversity. Structural equation modeling suggested that environmental factors determine vegetation composition, which in turn independently drives both plant diversity and productivity. Thus, the positive correlation between plant diversity and productivity is indirectly driven by vegetation composition, which is determined by environmental gradients in soil and topography.

A Psychometric Study of the Quality Perception Questionnaire

2012 ◽  
Vol 71 (2) ◽  
pp. 101-106 ◽  
Author(s):  
Raffaele Cioffi† ◽  
Anna Coluccia ◽  
Fabio Ferretti ◽  
Francesca Lorini ◽  
Aristide Saggino ◽  
...  
Keyword(s):  
Structural Equation ◽  
Factor Model ◽  
Equation Modeling ◽  
Fit Indices ◽  
Quality Perception ◽  
Italian Survey ◽  
Confirmatory Factor ◽  
Instrument Measuring ◽  
Hospital Structures

The present paper reexamines the psychometric properties of the Quality Perception Questionnaire (QPQ), an Italian survey instrument measuring patients’ perceptions of the quality of a recent hospital admission experience, in a sample of 4400 patients (Mage = 56.42 years; SD = 19.71 years, 48.8% females). The 14-item survey measures four factors: satisfaction with medical doctors, nursing staff, auxiliary staff, and hospital structures. First, we tested two models using a confirmatory factor analysis (structural equation modeling): a four orthogonal factor and a four oblique factor model. The SEM fit indices and the χ² difference suggested the acceptance of the second model. We then did a simulation using a bootstrap with 1000 replications. Results confirmed the four oblique factor solution. Third, we tested whether there were significant differences with respect to age or sex. The multivariate general linear model showed no significant differences in the factors with respect to sex or age.

Suicide Risk Among College Student

Crisis ◽  
2015 ◽  
Vol 36 (6) ◽  
pp. 416-423 ◽  
Author(s):  
Richard Shadick ◽  
Faedra Backus Dagirmanjian ◽  
Baptiste Barbot
Keyword(s):  
Sexual Minority ◽  
Students Of Color ◽  
Structural Equation ◽  
Suicide Risk ◽  
Equation Modeling ◽  
First Year ◽  
Chi Square ◽  
First Year College ◽  
Marginalized Groups ◽  
First Year College Students

Abstract. Background: Research on young adults in the general population has identified a relationship between sexual minority identification and risk for suicide. Differential rates of suicidal ideation and attempts have also been found across racial and ethnic groups. Aims: This study examined risk for suicide among university students, based on membership in one or more marginalized groups (sexual minority and racial minority identification). Method: Data were collected from first-year college students (N = 4,345) at an urban university. Structural equation modeling was employed to model a suicidality construct, based on which a "risk for suicide" category system was derived. Chi-square and logistic regression analyses were then conducted to estimate the relationship between the background variables of interest and suicide risk. Results: Students who identified as lesbian, gay, or bisexual (LGB) were associated with higher suicide risk than their heterosexual peers. Students of color were slightly less at risk than their heterosexual peers. However, LGB students of color were associated with elevated suicide risk relative to heterosexual peers. Conclusion: Results indicate that belonging to multiple marginalized groups may increase one's risk for suicide, though these effects are not simply additive. Findings highlight the complexity of the intersection between marginalized identities and suicidality.

Low Self-Control of Emotions as an Antecedent of Self-Reported Physical Symptoms: A Longitudinal Perspective

2001 ◽  
Vol 6 (1) ◽  
pp. 26-35 ◽  
Author(s):  
Marja Kokkonen ◽  
Lea Pulkkinen ◽  
Taru Kinnunen
Keyword(s):  
Structural Equation ◽  
Negative Emotions ◽  
Physical Symptoms ◽  
Self Control ◽  
Personality Characteristics ◽  
Equation Modeling ◽  
Eysenck Personality Questionnaire ◽  
Positive Direction ◽  
Data Collections ◽  
Low Self Control

The study was part of the Jyväskylä Longitudinal Study of Personality and Social Development, underway since 1968, in which children's low self-control of emotions was studied using teacher ratings at age 8 in terms of inattentiveness, shifting moods, aggression, and anxiety. The study was based on data from 112 women and 112 men who participated in the previous data collections at ages 8, 27, and 36. At age 27, the participants had been assessed in Neuroticism (N) using the Eysenck Personality Questionnaire , and at age 36 they filled in several inventories measuring, among others, conscious and active attempts to repair negative emotions in a more positive direction as well as physical symptoms. The present study used structural equation modeling to test the hypothesis that personality characteristics indicating low self-control of emotions at ages 8 and 27 are antecedents of self-reported physical symptoms at age 36; and that this relationship is indirect, mediated by attempts to repair negative emotions in a more positive direction. The findings showed, albeit for men only, that inattentiveness at age 8 was positively related to self-reported physical symptoms at age 36 via high N at age 27 and low attempts to repair negative emotions at age 36. Additionally, N at age 27 was directly linked to self-reported physical symptoms at age 36. The mediation of an active attempt to repair negative emotions was not found for women. Correlations revealed, however, that shifting moods and aggression in girls were antecedents of self-reported physical symptoms in adulthood, particularly, pain and fatigue.

Validating the Factor Structure of the Stigma of Suicide Scale–Short Form Spanish Version Among Healthcare Students

Crisis ◽  
2020 ◽  
pp. 1-5
Author(s):  
Ruthmarie Hernández-Torres ◽  
Paola Carminelli-Corretjer ◽  
Nelmit Tollinchi-Natali ◽  
Ernesto Rosario-Hernández ◽  
Yovanska Duarté-Vélez ◽  
...  
Keyword(s):  
Factor Structure ◽  
Structural Equation ◽  
Short Form ◽  
Small Sample Size ◽  
Small Sample ◽  
Spanish Version ◽  
Equation Modeling ◽  
Cross Sectional ◽  
Healthcare Students ◽  
Spanish Speaking

Abstract. Background: Suicide is a leading cause of death among Spanish-speaking individuals. Suicide stigma can be a risk factor for suicide. A widely used measure is the Stigma of Suicide Scale-Short Form (SOSS-SF; Batterham, Calear, & Christensen, 2013 ). Although the SOSS-SF has established psychometric properties and factor structure in other languages and cultural contexts, no evidence is available from Spanish-speaking populations. Aim: This study aims to validate a Spanish translation of the SOSS-SF among a sample of Spanish-speaking healthcare students ( N = 277). Method: We implemented a cross-sectional design with quantitative techniques. Results: Following a structural equation modeling approach, a confirmatory factor analysis (CFA) supported the three-factor model proposed by Batterham and colleagues (2013) . Limitations: The study was limited by the small sample size and recruitment by availability. Conclusion: Findings suggest that the Spanish version of the SOSS-SF is a valid and reliable tool with which to examine suicide stigma among Spanish-speaking populations.

Risk Factors and Mediators of Suicidal Ideation Among Korean Adolescents

Crisis ◽  
2018 ◽  
Vol 39 (1) ◽  
pp. 4-12 ◽  
Author(s):  
Yi Jin Kim ◽  
Sung Seek Moon ◽  
Jang Hyun Lee ◽  
Joon Kyung Kim
Keyword(s):  
High School Students ◽  
Suicidal Ideation ◽  
Structural Equation ◽  
Equation Modeling ◽  
Outcome Variable ◽  
Suicidal Behaviors ◽  
Thwarted Belongingness ◽  
Perceived Burdensomeness ◽  
Korean Adolescents ◽  
Related Stress

Abstract. Background: A significant number of Korean adolescents have suicidal ideations and it is more prevalent among adolescents than any other age group in Korea. Aims: This study was conducted to attain a better understanding of the contributing factors to suicidal ideation among Korean adolescents. Method: We recruited 569 high school students in Grades 10 and 11 in Pyeongtaek, Korea. The Beck Scale for Suicidal Ideation was used to measure suicidal ideation as the outcome variable. The Interpersonal Needs Questionnaire, the Beck Hopelessness Scale, the School Related Stress Scale, the Olweus Bully/Victim Questionnaire, and the Youth Risk Behavior Surveillance questions were used to measure thwarted belongingness and perceived burdensomeness, hopelessness, school-related stress, bullying, and previous suicidal behaviors, respectively. Data analyses included descriptive statistics and structural equation modeling. Results: The findings suggest that perceived burdensomeness, hopelessness, school-related stress, and previous suicidal behaviors have significant direct effects on suicidal ideation. Hopelessness fully mediated the relation between thwarted belongingness and suicidal ideation, and partially mediated between perceived burdensomeness, school-related stress, and suicidal ideation. Conclusion: These findings provide more specific directions for a multidimensional suicide prevention program in order to be successful in reducing suicide rates among Korean adolescents.

Implicit Association Test: Separating Transsituationally Stable and Variable Components of Attitudes toward Gay Men

2003 ◽  
Vol 50 (1) ◽  
pp. 33-48 ◽  
Author(s):  
Melanie C. Steffens ◽  
Axel Buchner
Keyword(s):  
Gay Men ◽  
Implicit Association Test ◽  
Structural Equation ◽  
Implicit Attitudes ◽  
Association Test ◽  
Situational Factors ◽  
Situational Factor ◽  
Equation Modeling ◽  
Implicit Attitude ◽  
Implicit Association

Implicit attitudes are conceived of as formed in childhood, suggesting extreme stability. At the same time, it has been shown that implicit attitudes are influenced by situational factors, suggesting variability by the moment. In the present article, using structural equation modeling, we decomposed implicit attitudes towards gay men into a person factor and a situational factor. The Implicit Association Test ( Greenwald, McGhee, & Schwartz, 1998 ), introduced as an instrument with which individual differences in implicit attitudes can be measured, was used. Measurement was repeated after one week (Experiment 1) or immediately (Experiment 2). Explicit attitudes towards gay men as assessed by way of questionnaires were positive and stable across situations. Implicit attitudes were relatively negative instead. Internal consistency of the implicit attitude assessment was exemplary. However, the within-situation consistency was accompanied by considerable unexplained between-situation variability. Consequently, it may not be adequate to interpret an individual implicit attitude measured at a given point in time as a person-related, trait-like factor.

Further Validity of the Japanese Version of the Ten Item Personality Inventory (TIPI-J)

2014 ◽  
Vol 35 (4) ◽  
pp. 236-244 ◽  
Author(s):  
Atsushi Oshio ◽  
Shingo Abe ◽  
Pino Cutrone ◽  
Samuel D. Gosling
Keyword(s):  
Big Five ◽  
Content Validity ◽  
Structural Equation ◽  
English Language ◽  
Full Range ◽  
Reliability And Validity ◽  
Japanese Version ◽  
Personality Inventory ◽  
Equation Modeling ◽  
Big Five Personality

The Ten Item Personality Inventory (TIPI; Gosling, Rentfrow, & Swann, 2003 ) is a widely used very brief measure of the Big Five personality dimensions. Oshio, Abe, and Cutrone (2012) have developed a Japanese version of the TIPI (TIPI-J), which demonstrated acceptable levels of reliability and validity. Until now, all studies examining the validity of the TIPI-J have been conducted in the Japanese language; this reliance on a single language raises concerns about the instrument’s content validity because the instrument could demonstrate reliability (e.g., retest) and some forms of validity (e.g., convergent) but still not capture the full range of the dimensions as originally conceptualized in English. Therefore, to test the content validity of the Japanese TIPI with respect to the original Big Five formulation, we examine the convergence between scores on the TIPI-J and scores on the English-language Big Five Inventory (i.e., the BFI-E), an instrument specifically designed to optimize Big Five content coverage. Two-hundred and twenty-eight Japanese undergraduate students, who were all learning English, completed the two instruments. The results of correlation analyses and structural equation modeling demonstrate the theorized congruence between the TIPI-J and the BFI-E, supporting the content validity of the TIPI-J.

Testing the Assumption of Uncorrelated Errors for Short Scales by Means of Structural Equation Modeling

2014 ◽  
Vol 35 (4) ◽  
pp. 201-211 ◽  
Author(s):  
André Beauducel ◽  
Anja Leue
Keyword(s):  
Structural Equation Modeling ◽  
Negative Correlation ◽  
Structural Equation ◽  
Error Score ◽  
Classical Test Theory ◽  
Test Theory ◽  
Equation Modeling ◽  
Eysenck Personality Questionnaire ◽  
Personality Questionnaire ◽  
True Score

It is shown that a minimal assumption should be added to the assumptions of Classical Test Theory (CTT) in order to have positive inter-item correlations, which are regarded as a basis for the aggregation of items. Moreover, it is shown that the assumption of zero correlations between the error score estimates is substantially violated in the population of individuals when the number of items is small. Instead, a negative correlation between error score estimates occurs. The reason for the negative correlation is that the error score estimates for different items of a scale are based on insufficient true score estimates when the number of items is small. A test of the assumption of uncorrelated error score estimates by means of structural equation modeling (SEM) is proposed that takes this effect into account. The SEM-based procedure is demonstrated by means of empirical examples based on the Edinburgh Handedness Inventory and the Eysenck Personality Questionnaire-Revised.

The Schoolwork Engagement Inventory

2012 ◽  
Vol 28 (1) ◽  
pp. 60-67 ◽  
Author(s):  
Katariina Salmela-Aro ◽  
Katja Upadaya
Keyword(s):  
Secondary School ◽  
Concurrent Validity ◽  
Structural Equation ◽  
Self Esteem ◽  
Equation Modeling ◽  
Validity And Reliability ◽  
Older Students ◽  
School Students ◽  
Factor Solution ◽  
Upper Secondary

This study introduces the Schoolwork Engagement Inventory (EDA), which measures energy, dedication, and absorption with respect to schoolwork. Structural equation modeling was used to assess the validity and reliability of the inventory among students attending postcomprehensive schools. A total of 1,530 (769 girls, 761 boys) students from 13 institutions (six upper-secondary and seven vocational schools) completed the EDA 1 year apart. The results showed that a one-factor solution had the most reliability and fitted best among the younger students, whereas a three-factor solution was most reliable and fit best among the older students. In terms of concurrent validity, depressive symptoms and school burnout were inversely related, and self-esteem and academic achievement were positively associated with EDA. Boys and upper-secondary-school students experienced lower levels of schoolwork engagement than girls and vocational-school students.

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