Learning from unrealized versus realized prices

Our market experiment investigates the extent to which traders learn from the price, differentiating between situations where orders are submitted before versus after the price has realized. When market participants have to submit their bids conditional on the price, they show a bias by reacting only to their private information and not to the hypothetical value of the price. In a sequential trading mechanism, where the price is known at the bid submission, bids react to price to an extent that is roughly consistent with the benchmark theory

Learning From Unrealized versus Realized Prices

Our experiments investigate the extent to which traders learn from the price, differentiating between situations where orders are submitted before versus after the price has realized. In simultaneous markets with bids that are conditional on the price, traders neglect the information conveyed by the hypothetical value of the price. In sequential markets where the price is known prior to the bid submission, traders react to price to an extent that is roughly consistent with the benchmark theory. The difference's robustness to a number of variations provides insights about the drivers of this effect

Influence des facteurs abiotiques sur la biodiversité des macroinvertebrés benthiques du cours d'eau Mgbaba, LékiéOuest dans la région du Centre Cameroun

             Les macroinvertébrés benthiques sont des organismes visibles à l’œil nu qui vivent dans les cours d’eau ou qui ne s’éloignent que de peu durant la majeure partie de leur vie. Dans le but de déterminer l’influence des facteurs abiotiques sur la biodiversité des macroinvertebrés benthiques dans un cours d'eau du dans la Lékié-Ouest, une étude a été conduite à Mgbaba de juillet 2022 en mai 2023. Les analyses physicochimiques et biologiques ont été réalisées suivant les méthodes classiques au Laboratoire d’Hydrobiologie et Environnement de la Faculté des Sciences de l’Université de Yaoundé 1. Les échantillonnages des macroinvertébrés benthiques ont été effectués suivant l’approche multihabitat, en utilisant un troubleau de forme carrée muni d’un filet de 400 µm d’ouverture de maille. Les organismes ainsi récoltés ont été fixés au formol 10% contenu dans des piluliers en verre. Au laboratoire, les spécimens ont été lavés à l’eau courante puis conservés dans de l’alcool à 70° avant les opérations d’identification et de comptage. Au cours de cette étude, 1152 individus ont été récoltés appartenant à 2 embranchements (Mollusques et Arthropodes), 3 classes, 10 ordres, 37 familles et 62 genres. La station Mbgaba 2 (MG2) prédomine avec 423 individus soit 36,71% d’abondance relative suivis de la station Mgbaba 3 (MG3) avec 417 individus soit 36,19% d’abondance relative enfin la station Mgbaba1avec 312 individus, soit 27,08% d’abondance relative. De manière générale, les résultats des analyses physicochimiques, biologiques et l'indice de diversité de Shannon et Weaver (H') révèlent que les eaux du cours d’eau Mgbaba sont dans la gamme de la bonne qualité écologique et que la riche spécifique des macroinvertébrés benthiques est riche et diversifiées. Par ailleurs, les tests d’Anova un facteur et Welch ont permis de déterminer s'il existait ou non des différences significatives entre les variables physicochimiques sur le plan spatio-temporel et le test Spearman (r) a permis de déterminer qu’il existe des corrélations entre paramètres physicochimiques et biologiques.    Benthic macroinvertebrates are organisms visible to the naked eye that live in waterways or that only move away a short distance during most of their lives. In order to determine the influence of abiotic factors on the biodiversity of benthic macroinvertebrates in a waterway in Lékié-Ouest, a study was conducted in Mgbaba from July 2022 to May 2023. Physicochemical and biological analyses were carried out using conventional methods at the Hydrobiology and Environment Laboratory of the Faculty of Sciences of the University of Yaoundé 1. Sampling of benthic macroinvertebrates was carried out using the multihabitat approach, using a square-shaped trough equipped with a 400 µm mesh size net. The organisms thus collected were fixed with 10% formalin contained in glass pill boxes. In the laboratory, the specimens were washed in running water and then preserved in 70° alcohol before identification and counting operations. During this study, 1152 individuals were collected belonging to 2 phyla (Molluscs and Arthropods), 3 classes, 10 orders, 37 families and 62 genera. The Mbgaba 2 station (MG2) predominates with 423 individuals or 36.71% relative abundance followed by the Mgbaba3 station (MG3) with 417 individuals or 36.19% relative abundance and finally the Mgbaba1 station with 312 individuals or 27.08% relative abundance. In general, the results of the physicochemical and biological analyses and the Shannon and Weaver diversity index (H') reveal that the waters of the Mgbaba stream are in the range of good ecological quality and that the specific richness of benthic macroinvertebrates is rich and diversified. In addition, the ANOVA one-way and Welch tests made it possible to determine whether or not there were significant differences between the physicochemical variables on the spatio-temporal level and the Spearman test (r) allowed us to determine that there are correlations between physicochemical and biological parameters

Decision-Making in Markets

Diese Dissertation erforscht, auf welchen unterschiedlichen Wegen Informationsverarbeitung Investitionsentscheidungen beeinflusst. Auf der Basis kontrollierter Laborexperimente wird untersucht, wie Entscheidungen mit der Art der Information sowie mit dem Entscheidungskontext variieren. Im ersten Kapitel legt ein Experiment die Schwierigkeit mit hypothetischem Denken bzw. mit dem Lernen aus hypothetischen Ereignissen offen. Im Kapitel Zwei untersucht ein anderes Experiment, wie Informationsverarbeitung die Reaktionen der Investoren auf Ambiguität verändert, denn ein eindeutiges, optimales Lernverhalten gibt es unter Ambiguität nicht. Das letzte Kapitel stellt anhand desselben Experiments die Unabhängigkeit zwischen dem Lernprozess und den Risikopräferenzen in Frage.This dissertation investigates various channels through which information processing affects investment decisions. Controlled laboratory experiments allow for studying how subjects’ decisions vary with the type of information and the decision-context. The experiment in the first chapter discloses the difficulty with contingent reasoning, i.e. learning from hypothetical events. A different experiment in Chapter Two analyzes how information processing changes investors’ reactions to ambiguity—an environment with multiple rational learning rules. Using the same experiment, the last chapter questions the independence between belief updating and risk preferences

Learning under Ambiguity: An Experiment in Gradual Information Processing

This experiment studies belief updating under ambiguity, using subjects' bid and ask prices for an asset with ambiguous payoff distribution. Bid and ask quotes allow for distinguishing between the two main paradigms of updating under ambiguity--full Bayesian updating and maximum likelihood updating. We find substantial heterogeneity in subjects' reaction to information. The majority of subjects (54\%) chose quotes that were in line with full Bayesian updating, while another, non-negligible, group (35\%) behaved like maximum likelihood updaters. (JEL: G11, C91, D81

The Resolution of Uncertainty in the Value and Probability Domains

We compare preferences for temporal resolution when uncertainty is resolved over a probability rather than a value. In various frameworks–e.g., Kreps and Porteus (1978)–, preferences over gradual versus one-shot resolution do not depend on whether values or probabilities define the main object of uncertainty. In our experiment, however, most subjects resolved uncertain values gradually but uncertain probabilities all at once–both in the gain and loss frames. This systematic discrepancy motivates an explanation for it that we call "process utility", which highlights the importance of information processing when deducing revealed preferences for temporal resolution from choice data

Antibacterial and antibiotic-potentiation activity of the constituents from aerial part of Donella welwitshii (Sapotaceae) against multidrug resistant phenotypes

Abstract Background The rise of multidrug-resistant (MDR) bacteria is a real public health problem worldwide and is responsible for the increase in hospital infections. Donella welwitschii is a liana or shrub belonging to the family Sapotaceae and traditionally used to cure coughs. Objective This study was conducted with the objective to validate the medicinal properties of this plant, the aerial part was studied for its phytochemical composition using column and PTLC chromatography and exploring its antibacterial and antibiotic-modifying activity as well as those of its phytochemicals. Methods The structures of the compounds were elucidated from their physical and spectroscopic data in conjunction with literature. The antibacterial activity of the isolated metabolites was performed toward a panel of MDR Gram negative and Gram-positive bacteria. The broth micro-dilution method was used to determine antibacterial activities, efflux pump effect using the efflux pump inhibitor (EPI) (phenylalanine-arginine-ß-naphthylamide (PAβN)), as well as the modulating activity of antibiotics. Monitoring the acidification of the bacterial growth medium was used to study the effects of the samples on the bacterial proton-ATPase pumps and cellular ATP production. Results Eleven compounds were isolated including pentacyclic triterpenes, C-glucosyl benzophenones. With a MIC value < 10 μg/mL, diospyric acid (7) significantly inhibited the growth of Escherichia coli AG102, Enterobacter aerogenes ATCC13048, Klebsiella pneumoniae KP55, Providencia stuartii NEA16 and Staphylococcus aureus MRSA3. 28-hydroxy-β-amyrin (8) significantly impaired the growth of Enterobacter aerogenes EA27, Klebsiella pneumoniae ATCC11296 and Staphylococcus aureus MRSA6; and oleanolic acid (9) strongly impaired the growth of Escherichia coli AG 102, Enterobacter aerogenes EA27 and Providencia stuartii PS2636. Diospyric acid (7) and 28-hydroxy-β-amyrin (8) induced perturbation of H+-ATPase pump and inhibition of the cellular ATP production. Moreover, at MIC/2 and MIC/4, compounds 7, 8, and 9 strongly improved the antibacterial activity of norfloxacin, ciprofloxacin and doxycycline with antibiotic-modulating factors ranging between 2 and 64. Conclusion The overall results of the current work demonstrate that diospyric acid (7), 28-hydroxy-β-amyrin (8) and oleanolic acid (9) are the major bioactive constituents of Donella welwitschia towards Gram-negative bacteria expressing MDR phenotypes