1,333 research outputs found
Combined Effects of Knowledge About Others' Opinions and Anticipation of Group Discussion on Confirmatory Information Search
There is conclusive evidence that information search processes are typically biased in favor of the information seekerâs own opinion (confirmation bias). Less is known about how knowledge about othersâ opinions affects this confirmatory information search. In the present study, the authors manipulated feedback about othersâ opinions and anticipation of group interaction. As predicted, the effect of knowledge about othersâ opinions on confirmatory information search depended on whether participants anticipated interacting with these others. Specifically, minority members anticipating a group discussion exhibited a particularly strong confirmation bias, whereas minority members who did not anticipate a discussion predominantly sought information opposing their opinion. For participants not anticipating group interaction, confidence about the correctness of oneâs decision mediated the impact of knowledge about othersâ opinions on confirmatory information search. Results are discussed with regard to the debiasing effect of preference heterogeneity on confirmatory information search in groups
ĐŃĐ”ĐœĐșĐ° ĐœĐ°ĐŽĐ”Đ¶ĐœĐŸŃŃĐž ŃĐ°Đ±ĐŸŃŃ ŃĐ”ŃŃĐ”ŃĐ”ĐœŃĐ°ŃĐŸĐłĐŸ ĐœĐ°ŃĐŸŃĐ° ĐĐšĐ-600
Virtual Notes:Annotations on the WWW for Learning Environments
This paper describes Virtual Notes, small yellow stickers which can be freely placed on instrumented HTML-pages using standard Internet technology. In a teaching and research environment they provide a user- friendly and flexible way of improving collaboration by annotations, feedback, post-its and blackboards
Beyond group-level explanations for the failure of groups to solve hidden profiles: The individual preference effect revisited
The individual preference effect supplements the predominant group-level explanations for the failure of groups to solve hidden profiles. Even in the absence of dysfunctional group-level processes, group members tend to stick to their suboptimal initial decision preferences due to preference-consistent evaluation of information. However, previous experiments demonstrating this effect retained two group-level processes, namely (a) social validation of information supporting the group membersâ initial preferences and (b) presentation of the additional information in a discussion format. Therefore, it was unclear whether the individual preference effect depends on the co-occurrence of these group-level processes. Here, we report two experiments demonstrating that the individual preference effect is indeed an individual-level phenomenon. Moreover, by a comparison to real interacting groups, we can show that even when all relevant information is exchanged and when no coordination losses occur, almost half of all groups would fail to solve hidden profiles due to the individual preference effect
Lernen aus WidersprĂŒchen â ein Ansatz fĂŒr Universal Design
Das Lernen aus WidersprĂŒchen ist ein im Seminar des Kölner SchĂŒlerlabors âUnser Raumschiff Erdeâ entstandenes Konzept, das sich insbesondere auch bei heterogenen Lerngruppen als Alternative zu Binnendifferenzierung bewĂ€hrt hat. Dieser Beitrag ordnet das Konzept in die Debatte ĂŒber Binnendifferenzierung ein und stellt den Bezug zu den klassischen allgemein-didaktischen Konzepten insbesondere von Feuser und Klafki her. Diese Einordnung zeigt, dass es systematische GrĂŒnde fĂŒr das Gelingen dieses Konzeptes im SchĂŒlerlabor gibt, die nicht dem konkreten Ursprungskontext geschuldet sind.Dies macht eine Ăbertragung in andere Kontexte vielversprechend
Biased Information Search in Homogeneous Groups: Confidence as a Moderator for the Effect of Anticipated Task Requirements
When searching for information, groups that are homogeneous regarding their membersâ prediscussion decision preferences show a strong bias for information that supports rather than conflicts with the prevailing opinion (confirmation bias). The present research examined whether homogeneous groups blindly search for information confirming their beliefs irrespective of the anticipated task or whether they are sensitive to the usefulness of new information for this forthcoming task. Results of three experiments show that task sensitivity depends on the groupsâ confidence in the correctness of their decision: Moderately confident groups displayed a strong confirmation bias when they anticipated having to give reasons for their decision but showed a balanced information search or even a disconfirmation bias (i.e., predominately seeking conflicting information) when they anticipated having to refute unterarguments. In contrast, highly confident groups demonstrated a strong confirmation bias independent of the anticipated task requirements
Lernen aus WidersprĂŒchen: Vom SchĂŒlerlabor zur Schulpraxis
Die Lernmethode âLernen aus WidersprĂŒchenâ â entwickelt im SchĂŒlerlabor der UniversitĂ€t zu Köln â wurde jetzt in den regulĂ€ren inklusiven Physikunterricht ĂŒbertragen und in einer 7. Klasse in Bonn erprobt und evaluiert. Dazu wurden im Rahmen einer Masterarbeit 5 Lerneinheiten zu je 3 Schulstunden zum Thema Optik entwickelt. Kern des Konzeptes ist, dass zu Beginn einer Lerneinheit von den SchĂŒlerinnen und SchĂŒlern (SuS) etliche Vermutungen zur ErklĂ€rung der PhĂ€nomene geĂ€uĂert und an die Tafel geschrieben werden. Alle Vermutungen, auch die auf Fehlvorstellungen beruhenden, werden gleichwertig behandelt, sodass WidersprĂŒche entstehen. Nach der âVermutungsphaseâ im Plenum arbeiten die SuS in Kleingruppen weiter (je 4 SuS), zunĂ€chst in einer Diskussionsphase, danach in der Experimentierphase, um so selbststĂ€ndig die richtige ErklĂ€rung zu erarbeiten. Die 5 Unterrichtseinheiten sind âSehvorgangâ, âReflexion und Streuungâ, Bau eines âSchĂŒlerspektroskopsâ, âFarbenâ und âAbsorptionâ. Die Auswertung geschah durch SchĂŒlerfragebögen (PrĂ€- und Post-Befragung) und durch aktive Beobachtung (2 unabhĂ€ngige Beobachter) einer ausgewĂ€hlten SuS-Gruppe. Es zeigte sich, dass die Arbeit mit WidersprĂŒchen in Kombination mit SchĂŒlerexperimenten einerseits gut funktioniert; andererseits hat sich die Zusammenarbeit in Kleingruppen als unerwartet problematisch erwiesen. Ferner kann festgestellt werden, dass â im Gegensatz zum Frontalunterricht â nahezu alle SuS in den Lernprozess einbezogen waren. Das Konzept ist offenbar gut fĂŒr den inklusiven Physikunterricht geeignet
Total Synthesis of the Indole Alkaloids Raputindol A and Raputimonoindole A-F
Eine Vielzahl von Indolalkaloiden wurde seit 2010 aus Raputia simulans und R. praetermissa (Rutaceae) isoliert. Alle besitzen eine unsubstituierte Enaminstruktur des Indols, eine Eigenschaft die nur selten bei anderen Naturstoffen zu finden ist. Das terpenoide, dimere Bisindolalkaloid Raputindol A besitzt eine lineare Cyclopenta[f]indol-Teilstruktur, wohingegen die Raputimonoindole A-F eine Furaneinheit unterschiedlicher Oxidationsstufen an der Indol-5-Position aufweisen. In dieser Arbeit wird die erste Totalsynthese dieser Naturstoffe berichtet und absolute Konfigurationen zugewiesen.
Die Cyclopenta[f]indol-Teilstruktur des Raputindol A wurde durch regioselektive Gold(I)-katalysierte Cycloisomerisierung von Propargylacetaten zugĂ€nglich. Chirale Liganden oder ChiralitĂ€tstransfer erlaubten keine enantioselektive Synthese. Die EinfĂŒhrung einer Isobutenyl-Seitenkette schlug unter diversen Bedingungen fehl. Sie konnte schlieĂlich durch eine Suzuki-Miyaura Kreuzkupplung installiert werden. Die regioselektive Reduktion des erhaltenen 1,3-Diens wurde durch LiDBB erreicht. Die Methode lieĂ sich nicht fĂŒr eine diastereoselektive Synthese modifizieren. Der zweite Indolkern wurde ĂŒber eine Heck-Kupplung eingefĂŒhrt, was in 6.6% Ausbeute ĂŒber 9 Stufen zu synthetischem Raputindol A fĂŒhrte. Die Enantiomere wurden per HPLC an chiraler Phase getrennt und ihre ECD-Spektren gemessen. Ein simuliertes ECD-Spektrum aus TD-DFT Rechnungen bestĂ€tigte die (R,R)-Konfiguration des Naturstoffs.
Eine zweite, diastereoselektive Synthese von Raputindol A, mit einer OH-dirigierten Hydrierung als SchlĂŒsselschritt, wurde entwickelt. Die regio- und diastereoselektive Hydrierung eines 1,3-Diens wurde durch den Crabtree-Katalysator erreicht. Die Wittig-Olefinierung eines alpha-quartĂ€ren Aldehyds fĂŒhrte zu einer noch nie berichteten Eliminierung von Formaldehyd. Die Synthese von Raputindol A wurde mit einer verbesserten Ausbeute von 18% ĂŒber 13 Stufen durch Takai-Olefinierung und Suzuki-Miyaura Kreuzkupplung abgeschlossen.
Raputimonoindol B wurde durch Ir-katalysierte Borylierung und Suzuki-Miyaura Kreuzkupplung synthetisiert. Durch einfache Transformationen wurden die Raputimonoindole C und D aus Raputimonoindol B erhalten. Aus enantiomerenreinen 5-(1-Hydroxyallyl)-indolen konnten die Raputimonoindole A, E und F aufgebaut werden. Eine diastereoselektive Domino Heck-Suzuki Reaktion ergab Raputimonoindol A, wohingegen eine Ringschlussmetathese zu den Raputimonoindolen E und F fĂŒhrte.A variety of indole alkaloids have been isolated from Raputia simulans und R. praetermissa (Rutaceae) since 2010. All of them possess an unsubstituted enamine section of the indole core, a trait rarely found in other natural products. The terpenoid, dimeric bisindole alkaloid raputindole A exhibits a linear cyclopenta[f]indole partial structure, whereas the raputimonoindoles A-F feature differently oxidized furan moieties at the indole-5-position. In this work, the first total synthesis for each of these natural products is reported and absolute configurations are assigned.
The cyclopenta[f]indole structure of raputindole A was accessed by a regioselective, Gold(I)-catalyzed cycloisomerization of propargylic acetates. Chiral ligands or chirality transfer did not allow for an enantioselective synthesis. The introduction of an isobutenyl side chain failed under various conditions. Finally, Suzuki-Miyaura cross coupling allowed for its installation. The challenging regioselective reduction of the obtained 1,3-diene was achieved by the use of LiDBB. Unfortunately, this method could not be modified towards diastereoselectivity. Introduction of the second indole moiety via Heck coupling gave access to synthetic raputindole A for the first time in 6.6% yield over 9 steps. The enantiomers were separated by chiral phase HPLC and their ECD spectra were recorded. A simulated ECD spectrum from TD-DFT calculations revealed the natural products absolute configuration to be (R,R).
A second generation, diastereoselective synthesis of raputindole A was developed featuring an OH-directed hydrogenation as key step. The regio- and diastereoselective hydrogenation of a 1,3-diene was achieved by the use of Crabtreeâs catalyst. Wittig-type olefination of an alpha-quaternary aldehyde revealed an unprecedented elimination of formaldehyde. Finally, the synthesis was completed by Takai-Olefination and Suzuki-Miyaura cross coupling, giving raputindole A in an improved yield of 18% over 13 steps.
Raputimonoindole B was synthesized in one step via Ir-catalyzed borylation and subsequent Suzuki-Miyaura cross coupling. By simple transformations, raputimonoindoles C and D can be reached from raputimonoindole B. From enantiopure 5-(1-hydroxyallyl)-indoles raputimonoindoles A, E and F can be build up. A diastereoselective domino Heck-Suzuki reaction efficiently led to raputimonoindole A, whereas alkene ring-closing metathesis gave access to raputimonoindole E and F
Strongly inhibited spontaneous emission of PbS quantum dots covalently bound to 3D silicon photonic band gap crystals
We present an optical study of the spontaneous emission of lead sulfide (PbS) nanocrystal quantum dots in three-dimensional (3D) photonic band gap crystals made from silicon. The nanocrystals emit in the near-infrared (NIR) range to be compatible with the 3D silicon nanophotonics. The nanocrystals are covalently bonded to polymer brush layers that are grafted from the Si-air interfaces inside the nanostructure using surface-initiated atom transfer radical polymerization (SI-ATRP), and their presence and position of the quantum dots was previously characterized by synchrotron X-ray fluorescence tomography. We report both continuous wave (cw) emission spectra and time-resolved time-correlated single photon counting. In time-resolved measurements, we observe that the total emission rate greatly increases when the quantum dots are transferred from suspension to the silicon nanostructures, likely due to quenching (or increased non-radiative decay) that is tentatively attributed to the presence of Cu-catalyst during the synthesis. In this regime, continuous wave emission spectra are known to be proportional to the radiative rate and thus to the local density of states. In spectra normalized to those taken on flat silicon outside the crystals, we observe a broad and deep stop band that we attribute to a 3D photonic band gap with a relative bandwidth up to 26%. The shapes of the relative emission spectra match well with the theoretical density of states spectra calculated with the plane wave expansion. The observed inhibition is 5 to 30 times, similar to previously reported record inhibitions, yet for completely coincidental reasons. Our results are relevant to applications in photochemistry, sensing, photovoltaics, and to efficient miniature light sources
Social validation in group decision making: differential effects on the decisional impact of preference-consistent and preference-inconsistent information
"Shared information has a stronger impact on group decisions than unshared information. A prominent explanation for this phenomenon is that shared information can be socially validated during group discussion and, hence, is perceived as more accurate and relevant than unshared information. In the present study we argue that this explanation only holds for preference-inconsistent information (i.e., information contradicting the group membersâ initial preferences) but not for preference-consistent information. In Experiments 1 and 2 participants studied the protocol of a fictitious group discussion. In this protocol, we manipulated which types of information were socially validated. As predicted, social validation increased the decisional impact of preference-inconsistent but not preference-consistent information. In both experiments the effect of social validation was mediated by the perceived quality of information. Experiment 3 replicated the results of the first two experiments in an interactive setting in which two confederates discussed a decision case face-to-face with one participant." [author's abstract
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