The Stability of Information Cascades: How Herd Behavior Breaks Down

We extend the standard model of information cascades to situations where agents have to choose between switching to a new alternative or not. In particular, we add two new features to the standard model. First, agents continue to receive signals after they have chosen 'switching'; and second agents may revert their earlier decisions. The focus of the paper is to analyze how information is passed on within an information cascade, and the conditions under which breakdown occurs. We identify rules which describe the learning process and run simulations to estimate the properties of the information cascade. ZUSAMMENFASSUNG - (Zur Stabilität der Informationskaskade: Wann bricht Herdenverhalten ab?) Wir erweitern das Standardmodel der Informationskaskade. Durch die Erweiterung lassen sich Situationen modellieren, die den Individuen die Wahl zwischen einer neuen Alternative und dem bewährten lassen. Die Erweiterung besteht aus zwei Aspekten. Erstens erhalten die Individuen weiterhin Signale, nachdem sie sich für die neue Alternative entschieden haben. Zweitens können sie ihre Entscheidung später wieder zurücknehmen. Wir untersuchen wie sich Information innerhalb der Informationskaskade ausbreitet und unter welchen Bedingungen die Informationskaskade abbricht. Wir beschreiben den Lernprozeß der Individuen und führen eine Simulation des Prozesses durch.

Three-Dimensional Morphodynamic-Numerical Computations of Initiation and Propagation of River Dunes

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Staff and student opinions of the inclusion of practical work in higher education chemistry courses in England: What are the perceived objectives and outcomes?

Practical work is seen as an essential part of science courses. However, practical work is very resource intensive and in the current HE environment, in which academics will inevitably find themselves teaching more students with fewer resources, it is important to justify the cost in terms of educational benefit and so the objectives must be clear.This report describes the results of a survey of students undertaking chemistry undergraduate courses and staff in Higher Education chemistry departments in England. These surveys aimed to ascertain the range of practical work being carried out, alongside staff and student opinions of practical work. It also examined the reasons why practical work is included in undergraduate courses and what students take away from participating

Alternate Bar Instability as a Verification Test of a Morphodynamic-Numerical Model

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Synthesis of tetraazamacrocyclic complexes: Biomedical applications

Tetraazamacrocyclic frameworks of 1,4,7,10-tetraazacylcododecane (cyclen) and 1,4,8,11-tetraazacyclotetradecane (cyclam) with functional pendent arms and porphyrins with solubilising polyethylene glycol (PEG) chains have been synthesised. The pendent arms possess different properties which tailor the metal complex towards a particular role

Swahili Loanwords in Oromo

It is not unexpected that we can find several Swahili-loanwords in Oromo because Swahili- and Oromo speaking people were neighbours for, at least, several centuries. If we are looking for Swahili-loanwords in Oromo we have, of course, to examine the southern Oromo-dialects first

Host-plant resistance of Arabidopsis ecotypes with different glucosinolate profile for different phytophagous insect

Die Modellpflanze Arabidopsis thaliana (L.) gehört zur Familie der Brassicaceae, welche zur Herbivorenabwehr das Glucosinolat(GS)-Myrosinase-System, auch die Senfölbombe genannt, besitzt. Neben der primären Funktion der GS und korrespondierender Hydrolyseprodukte zur Abwehr von Generalisten unter den Insekten sowie Pathogenen (GIAMOUSTARIS & MITHEN, 1995, TIERENS et al., 2001), nutzen zahlreiche auf Brassicaceae spezialisierte Insekten diese Sekundärmetabolite zur Wirtspflanzenfindung und Akzeptanz (RENWICK, 2002). Mehr als 120 verschiedene GS wurden bisher beschrieben, welche sich durch die Seitenkettenreste am Aglucon (ß-Thioglucosid) unterscheiden (FAHEY et al., 2001). Hierbei werden die GS in drei Klassen unterteilt: 1) in A. thaliana zumeist aus Methionin gebildete aliphatische GS, 2) von Tryptophan abgeleitete Indolyl-GS und 3) von Phenylalanin abstammende aromatische GS. Die Indolyl-GS sind uniform verbreitet in der Brassicaceae-Familie und normalerweise in allen A. thaliana-Ökotypen vorhanden, wobei gezeigt wurde, dass diese stark durch Umweltfaktoren beeinflusst werden (KLIEBENSTEIN et al., 2001, RAYBOLD & MOYES, 2001). Im Gegensatz hierzu ist die aliphatische S-Zusammensetzung in A. thaliana-Ökotypen und Brassica sehr variabel, und die Seitenkettenmodifizierung ist stark genetisch determiniert (KLIEBENSTEIN et al., 2001, LI & QUIROS, 2002). Bisher wurde der Funktion aliphatischer GS-Diversität in Bezug auf ihre mögliche Bedeutung für die Resistenz gegenüber Insekten nicht ausreichende Aufmerksamkeit geschenkt. Deshalb überprüften wir, ob sich ein unterschiedlicher GS-Phäno- / Genotyp auf die Wirtspflanzeneignung für verschiedene spezialisierte phytophage Insekten auswirkt.The model plant Arabidopsis thaliana (L.) belongs to the family Brassicaceae, which is characterized by the glucosinolate(GS)-myrosinase defense system. Indolyl GS are relatively uniform distributed in A. thaliana ecotypes while aliphatic GS profiles are diverse. We used ecotypes with different aliphatic GS profile to test the function of such diversity in plant resistance against insects. Main GS detected were: methylsulfinylbutyl GS in Col-0 and AA-0, allyl GS in Cnt- 1 and Can-0 as well as 3-hydroxypropyl GS in Ka-0. Corresponding GS hydrolysis products of Col- 0 were isothiocyanates, but all other ecotypes produced nitriles (epithionitriles). Bioassays were conducted with two aphids, the generalist Myzus persicae (Sulzer) and the specialist Brevicoryne brassicae (L.), two caterpillars, the polyphagous noctuid Spodoptera exigua (Hübner) and the oligophagous pierid Pieris rapae (L.) as well as one specialist beetle Phaedon cochleariae (F.). Significant differences in insect performance on ecotypes were detected for the aphid and caterpillar species but not for P. cochleariae. Best insect performance was on AA-0, whereby this ecotype showed lowest aliphatic GS content of ecotypes. Interestingly, caterpillar performances measured as percent weight gain was different on Ka-0 and Cnt-1. P. rapae performed worse on Ka- 0 and good on Cnt-1 while S. exigua weight gain was better on Ka-0 but poor on Cnt-1. Several factors are considered in this study to explain different insect performance on ecotypes: different constitutive GS level, major aliphatic GS produced, and dominant hydrolysis products formed

Measurements of Transverse Transport and the Effect of Suspended Load

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Variability of aliphatic glucosinolates in Arabidopsis thaliana (L.) – Impact on glucosinolate profile and insect resistance

The glucosinolate(GS)-myrosinase system of Brassicaceae, including the model plant Arabidopsis thaliana (L.), comprises a defence which is effective especially against generalist herbivores. Based on their side chain structure GS are grouped into aliphatic, aromatic, and indolyl GS. Indolyl GS are widely distributed among A. thaliana ecotypes and the Brassicaceae family, but the presence of aliphatic GS is variable and under strong genetic control. We investigated the effect of AOP gene expression on the side chain modifications of GS and the impact on insect resistance. AOP2 and AOP3 genes from Mr-0 and Sap-0 ecotypes, respectively, were crossbred into the methylsulfinyl GS producing Gie-0. Successful crosses were heterozygote plants which produced allyl (AOP2) or 3-hydroxypropyl GS (AOP3). After self-pollination, the chemical profile of the F3 generation of plants was screened to identify homozygote lines. Homozygote lines producing 3-hydroxypropyl GS were compared to methylsulfinyl GS, which were used to study the impact of GS structure on insect performance in first experiments. Our experiments revealed that methylsulfinyl GS containing ecotype lines were more resistant to the generalist caterpillar Spodoptera exigua (Hübner) and to the specialist caterpillar Pieris brassicae (L.) than the lines containing hydroxypropyl GS as main compounds

An introduction to the recent literature on approaches to work-based learning

The term work-based learning is widely used throughout the literature, academia and industry to describe a multiplicity of approaches by which one can learn through work. The complex nature of work-based learning can often lead to confusion when designing courses which aim to implement such an approach.This review will focus on:The rationale for conducting work-based learning.The varieties of approaches to work-based learning that are currently implemented.Student opinions of work-based learning.How to resolve any implementation and communication issues.There are many approaches to developing work-based learning modules, courses and projects that utilise learning at, learning for, and learning through work. This paper aims to review the literature in these areas