The Effect of Central Exit Examinations on Student Achievement: Quasi-experimental Evidence from TIMSS Germany

This paper makes use of the regional variation in schooling legislation within the German secondary education system to estimate the causal effect of central exit examinations on student performance. We propose a difference-in-differences framework that exploits the quasi-experimental nature of the German TIMSS middle-school sample. The estimates show that students in federal states with central exit examinations clearly outperform students in other federal states, but that only part of the difference can be attributed to central exit examinations. Our results suggest that central examinations increase student achievement by about one third school year equivalent.education, central examinations, difference-in-differences, quasi-experiment

The role of raffinose in the cold acclimation response of Arabidopsis thaliana

AbstractIn many plants raffinose family oligosaccharides are accumulated during cold acclimation. The contribution of raffinose accumulation to freezing tolerance is not clear. Here, we investigated whether synthesis of raffinose is an essential component for acquiring frost tolerance. We created transgenic lines of Arabidopsis thaliana accessions Columbia-0 and Cape Verde Islands constitutively overexpressing a galactinol synthase (GS) gene from cucumber. GS overexpressing lines contained up to 20 times as much raffinose as the respective wild-type under non-acclimated conditions and up to 2.3 times more after 14 days of cold acclimation at 4 °C. Furthermore, we used a mutant carrying a knockout of the endogenous raffinose synthase (RS) gene. Raffinose was completely absent in this mutant. However, neither the freezing tolerance of non-acclimated leaves, nor their ability to cold acclimate were influenced in the RS mutant or in the GS overexpressing lines. We conclude that raffinose is not essential for basic freezing tolerance or for cold acclimation of A. thaliana

Differential predictors for alcohol use in adolescents as a function of familial risk

Abstract: Traditional models of future alcohol use in adolescents have used variable-centered approaches, predicting alcohol use from a set of variables across entire samples or populations. Following the proposition that predictive factors may vary in adolescents as a function of family history, we used a two-pronged approach by first defining clusters of familial risk, followed by prediction analyses within each cluster. Thus, for the first time in adolescents, we tested whether adolescents with a family history of drug abuse exhibit a set of predictors different from adolescents without a family history. We apply this approach to a genetic risk score and individual differences in personality, cognition, behavior (risk-taking and discounting) substance use behavior at age 14, life events, and functional brain imaging, to predict scores on the alcohol use disorders identification test (AUDIT) at age 14 and 16 in a sample of adolescents (N = 1659 at baseline, N = 1327 at follow-up) from the IMAGEN cohort, a longitudinal community-based cohort of adolescents. In the absence of familial risk (n = 616), individual differences in baseline drinking, personality measures (extraversion, negative thinking), discounting behaviors, life events, and ventral striatal activation during reward anticipation were significantly associated with future AUDIT scores, while the overall model explained 22% of the variance in future AUDIT. In the presence of familial risk (n = 711), drinking behavior at age 14, personality measures (extraversion, impulsivity), behavioral risk-taking, and life events were significantly associated with future AUDIT scores, explaining 20.1% of the overall variance. Results suggest that individual differences in personality, cognition, life events, brain function, and drinking behavior contribute differentially to the prediction of future alcohol misuse. This approach may inform more individualized preventive interventions

Differential predictors for alcohol use in adolescents as a function of familial risk

Abstract: Traditional models of future alcohol use in adolescents have used variable-centered approaches, predicting alcohol use from a set of variables across entire samples or populations. Following the proposition that predictive factors may vary in adolescents as a function of family history, we used a two-pronged approach by first defining clusters of familial risk, followed by prediction analyses within each cluster. Thus, for the first time in adolescents, we tested whether adolescents with a family history of drug abuse exhibit a set of predictors different from adolescents without a family history. We apply this approach to a genetic risk score and individual differences in personality, cognition, behavior (risk-taking and discounting) substance use behavior at age 14, life events, and functional brain imaging, to predict scores on the alcohol use disorders identification test (AUDIT) at age 14 and 16 in a sample of adolescents (N = 1659 at baseline, N = 1327 at follow-up) from the IMAGEN cohort, a longitudinal community-based cohort of adolescents. In the absence of familial risk (n = 616), individual differences in baseline drinking, personality measures (extraversion, negative thinking), discounting behaviors, life events, and ventral striatal activation during reward anticipation were significantly associated with future AUDIT scores, while the overall model explained 22% of the variance in future AUDIT. In the presence of familial risk (n = 711), drinking behavior at age 14, personality measures (extraversion, impulsivity), behavioral risk-taking, and life events were significantly associated with future AUDIT scores, explaining 20.1% of the overall variance. Results suggest that individual differences in personality, cognition, life events, brain function, and drinking behavior contribute differentially to the prediction of future alcohol misuse. This approach may inform more individualized preventive interventions

Untersuchungen eines ökologischen Phänomens unter Verwendung von chemischen und molekularen Methoden

Chapter 1 General introduction and thesis outline 1 Chapter 2 How plants give early herbivore alert: Volatile terpenoids attract parasitoids to egg-infested elms 9 Chapter 3 Smelling the tree and the forest – elm background odours affect egg parasitoid orientation to herbivore induced terpenoids 10 Chapter 4 An elm EST database for identifying leaf beetle egg-induced defense genes 11 Chapter 5 Elm defence: From a morphological over a chemical to a genomic perspective 13 Chapter 6 Summary 56 Zusammenfassung 60 Danksagung 65 Eigenständigkeitserklärung 67 Curriculum vitae 68Plants can defend themselves against insect herbivory prior to larval feeding damage through response to egg deposition on their leaves. Egg deposition by the herbivorous leaf beetle Xanthogaleruca luteola (Müller) (Coleoptera: Chrysomelidae) induces the emission of leaf volatiles in the European field elm Ulmus minor Mill. (Ulmaceae). This volatile blend attracts the egg parasitoid wasp Oomyzus gallerucae (Hymenoptera: Eulophidae), which destroys the insect eggs by parasitising, thus protecting indirectly the plant. To elucidate the relevance of terpenoids for parasitoid attraction, elms were treated with inhibitors of terpenoid biosynthesis, and attractiveness of odour of these elms to the parasitoid was tested. Laboratory olfactometer assays revealed that inhibitor treatment of elm leaves rendered oviposition-induced elm odour unattractive for the egg parasitoid. Field studies corroborated the findings of the ability of O. gallerucae to orientate towards single terpenoid volatiles. Lab and field studies indicated how host location in a plant - herbivore -parasitoid interaction might proceed under natural conditions. It was concluded that O. gallerucae locates eggs of its host on elms by orientation towards key sesquiterpenoids emitted in enhanced quantities by induced elm and received in the presence of background odour released from non-attacked elm. In contrast, odorous backgrounds consisting of high quantities of green leaf volatiles - as released from feeding-attacked elm leaves - negatively affect the host location behaviour of this parasitoid species. Knowledge on the molecular-genetic responses of tree species to insect egg deposition on their leaves is scarce. Therefore an EST (expressed sequence tags) database was generated of elm leaves after infestation (eggs, feeding) with the elm leaf beetle X. luteola. This elm database consisting of 361,196 ESTs that clustered into 52,823 unique transcripts. Comparative in silico analysis of hundreds of transcripts of genes revealed differences in the transcript signature of differently treated elm leaves in comparison to untreated elms. For the first time it was shown for a tree species that insect eggs can induce changes in transcript levels of genes involved in the primary as well as secondary metabolism. Morphological, chemical and molecular aspects of defence mechanisms of elms against biotic stressors were reviewed. However, this review demonstrates the lack of knowledge on compounds and genes playing a role in the defence of elms against pests and diseases. After the massive reduction of elm abundance worldwide by especially the Dutch elm disease, there is a revival of interest in elms. Further research is required to understand the complex mechanisms of elm defence against biotic stressors and to use this knowledge as valuable tool in sustainable pest management.Pflanzen können auf Eiablagen von Insekten auf ihren Blättern reagieren und sich dadurch gegen herbivore Insekten verteidigen, bevor deren Larven mit dem Fraß beginnen. Die Eiablage des herbivoren Ulmenblattkäfers Xanthogaleruca luteola (Müller) (Coleoptera: Chrysomelidae) induziert die Freisetzung von Blattdüften in der Europäischen Feldulme Ulmus minor Mill. (Ulmaceae). Dieser eiablageinduzierte Duft lockt den Eiparasitoiden Oomyzus gallerucae (Hymenoptera: Eulophidae) an, welcher die Käfereier durch Parasitierung zerstört und dadurch indirekt die Pflanze schützt. Um die Relevanz von eiablageinduzierten Terpenoiden bei der Anlockung von Parasitoiden aufzuklären, wurden Ulmen mit Inhibitoren für die Terpenoidbiosynthese behandelt und der resultierende Ulmenduft auf seine Attraktivität für den Parasitoiden untersucht. Wie Olfaktometertests im Labor zeigten, hatte der eiablageinduzierte Ulmenduft seine Attraktivität für den Eiparasitoiden nach Inhibitorbehandlung der Ulmenpflanzen verloren. Freilanduntersuchungen bestätigten die Annahme, dass einzelne Terpenoide den Eiparasitoiden anlocken können. Labor- und Freilandstudien zeigten, wie die Wirtsfindung in einer solchen Pflanzen-Herbivor-Parasitoid Interaktion unter natürlichen Bedingungen ablaufen könnte. O. gallerucae lokalisiert die Wirtseier auf Ulmen, indem sie sich zu Sequiterpenoiden hin orientiert, die eine Schlüsselfunktion bei der Anlockung dieser Parasitoide haben und in größerer Menge von induzierten Ulmen abgegeben werden. Diese Sesquiterpenoide können auch in Anwesenheit eines Hintergrundduftes von unbefallenen Ulmen wahrgenommen werden. Im Gegensatz dazu beeinflusst ein Hintergrundduft, welcher zu größeren Anteilen aus grünen Blattdüften besteht, die Wirtssuche dieser Parasitoidenart negativ. Der Wissensstand über die molekular-genetischen Reaktionen von Bäumen auf Insekten Eiablage ist sehr gering. Daher wurde eine EST (Expressed Sequence Tag), Datenbank aus Ulmenblättern nach Befall (Fraß, Eier) durch den Ulmenblattkäfer X. luteola generiert. Diese Datenbank besteht aus 361.196 ESTs, die zu 52.823 spezifischen Transkripten zusammengefasst sind. Durch vergleichende in silico Analysen von hunderten von Gentranskripten wurden Unterschiede im Transkriptommuster von Ulmenblättern nach den verschiedenen Behandlungen aufgedeckt. Zum ersten Mal wurde hier für eine Baumart demonstriert, dass Insekteneier Veränderungen in Transkriptraten von Genen aus dem Primär- sowie Sekundärstoffwechsel auslösen können. In einem Übersichtsartikel wurden morphologische, chemische und molekulare Aspekte der Ulmenverteidigung zusammengefasst. Dieser Übersichtsartikel demonstriert, wie wenig bisher über Metabolite und Gene bekannt ist, welche bei der Verteidigung von Ulmen eine Rolle spielen, obwohl das Interesse an Ulmen nach ihrer massiven Vernichtung durch die Holländische Ulmenkrankheit wieder zunimmt. Es besteht weiterer Forschungsbedarf, um tiefere Einblicke in die komplexen Verteidigungsmechanismen von Ulmen gegen biotische Stressoren zu erhalten und um diese als ein wertvolles Werkzeug bei der nachhaltigen Schädlingsbekämpfung verwenden zu können

An elm EST database for identifying leaf beetle egg-induced defense genes

BACKGROUND: Plants can defend themselves against herbivorous insects prior to the onset of larval feeding by responding to the eggs laid on their leaves. In the European field elm (Ulmus minor), egg laying by the elm leaf beetle ( Xanthogaleruca luteola) activates the emission of volatiles that attract specialised egg parasitoids, which in turn kill the eggs. Little is known about the transcriptional changes that insect eggs trigger in plants and how such indirect defense mechanisms are orchestrated in the context of other biological processes. RESULTS: Here we present the first large scale study of egg-induced changes in the transcriptional profile of a tree. Five cDNA libraries were generated from leaves of (i) untreated control elms, and elms treated with (ii) egg laying and feeding by elm leaf beetles, (iii) feeding, (iv) artificial transfer of egg clutches, and (v) methyl jasmonate. A total of 361,196 ESTs expressed sequence tags (ESTs) were identified which clustered into 52,823 unique transcripts (Unitrans) and were stored in a database with a public web interface. Among the analyzed Unitrans, 73% could be annotated by homology to known genes in the UniProt (Plant) database, particularly to those from Vitis, Ricinus, Populus and Arabidopsis. Comparative in silico analysis among the different treatments revealed differences in Gene Ontology term abundances. Defense- and stress-related gene transcripts were present in high abundance in leaves after herbivore egg laying, but transcripts involved in photosynthesis showed decreased abundance. Many pathogen-related genes and genes involved in phytohormone signaling were expressed, indicative of jasmonic acid biosynthesis and activation of jasmonic acid responsive genes. Cross-comparisons between different libraries based on expression profiles allowed the identification of genes with a potential relevance in egg-induced defenses, as well as other biological processes, including signal transduction, transport and primary metabolism. CONCLUSION: Here we present a dataset for a large-scale study of the mechanisms of plant defense against insect eggs in a co-evolved, natural ecological plant–insect system. The EST database analysis provided here is a first step in elucidating the transcriptional responses of elm to elm leaf beetle infestation, and adds further to our knowledge on insect egg-induced transcriptomic changes in plants. The sequences identified in our comparative analysis give many hints about novel defense mechanisms directed towards eggs

An elm EST database for identifying leaf beetle egg-induced defense genes

Abstract Background Plants can defend themselves against herbivorous insects prior to the onset of larval feeding by responding to the eggs laid on their leaves. In the European field elm (Ulmus minor), egg laying by the elm leaf beetle ( Xanthogaleruca luteola) activates the emission of volatiles that attract specialised egg parasitoids, which in turn kill the eggs. Little is known about the transcriptional changes that insect eggs trigger in plants and how such indirect defense mechanisms are orchestrated in the context of other biological processes. Results Here we present the first large scale study of egg-induced changes in the transcriptional profile of a tree. Five cDNA libraries were generated from leaves of (i) untreated control elms, and elms treated with (ii) egg laying and feeding by elm leaf beetles, (iii) feeding, (iv) artificial transfer of egg clutches, and (v) methyl jasmonate. A total of 361,196 ESTs expressed sequence tags (ESTs) were identified which clustered into 52,823 unique transcripts (Unitrans) and were stored in a database with a public web interface. Among the analyzed Unitrans, 73% could be annotated by homology to known genes in the UniProt (Plant) database, particularly to those from Vitis, Ricinus, Populus and Arabidopsis. Comparative in silico analysis among the different treatments revealed differences in Gene Ontology term abundances. Defense- and stress-related gene transcripts were present in high abundance in leaves after herbivore egg laying, but transcripts involved in photosynthesis showed decreased abundance. Many pathogen-related genes and genes involved in phytohormone signaling were expressed, indicative of jasmonic acid biosynthesis and activation of jasmonic acid responsive genes. Cross-comparisons between different libraries based on expression profiles allowed the identification of genes with a potential relevance in egg-induced defenses, as well as other biological processes, including signal transduction, transport and primary metabolism. Conclusion Here we present a dataset for a large-scale study of the mechanisms of plant defense against insect eggs in a co-evolved, natural ecological plant–insect system. The EST database analysis provided here is a first step in elucidating the transcriptional responses of elm to elm leaf beetle infestation, and adds further to our knowledge on insect egg-induced transcriptomic changes in plants. The sequences identified in our comparative analysis give many hints about novel defense mechanisms directed towards eggs.</p

Left ventricular outflow tract obstruction and its impact on systolic ventricular function and exercise capacity in adults with a subaortic right ventricle

BACKGROUND: In biventricular hearts the filling and contractility of one ventricle affects the performance of the other. In this study, we compared right ventricular systolic function and exercise capacity in patients with a subaortic right ventricle (RV) in relation to the presence of a left ventricular outflow tract obstruction (LVOTO). METHODS: Retrospective chart review of adults with congenitally corrected transposition of the great arteries (ccTGA) or with a previous atrial switch procedure for complete TGA (D-TGA). A LVOTO was defined by a peak instantaneous systolic gradient>20mmHg. Right and left ventricular ejection fraction (EF) were measured by cardiac magnetic resonance imaging (CMR), and exercise capacity as the predicted peak oxygen consumption (peak VO) on a cycle ergometer. RESULTS: We identified 79 clinically stable adults (age 33±10years, 70% male). Nine patients (11%) had cc-TGA and 70 patients had (89%) D-TGA. Thirteen patients (16%) had a LVOTO with a mean peak instantaneous systolic gradient of 43±22mmHg. Patients with a LVOTO had higher left (68±7% vs. 60±9%, p=0.01) and right ventricular EF (52±8 vs. 46±9%, p=0.05) by CMR compared to patients without LVOTO. In a multivariate regression analysis with left ventricular EF and LVOTO as predictors, only left ventricular EF was independently associated with right ventricular EF (correlation coefficient 0.41, p<0.01). The presence of a LVOTO was not associated with improved exercise capacity. CONCLUSIONS: In adults with a subaortic RV, a pressure loaded subpulmonary left ventricle has a beneficial effect on systemic right ventricular EF

Cardiac magnetic resonance imaging in congenital heart disease

Position paper of a group of Swiss paediatric and adult cardiologists, and radiologists performing cardiac magnetic resonance in congenital heart disease, endorsed by the working groups “Adult Congenital Heart Disease” (WATCH) and “Echocardiography and Cardiac Imaging” of the Swiss Society of Cardiology, the Swiss Society of Pediatric Cardiology and the Ressort Cardiac Imaging of the Swiss Society of Radiology