Self-destroying expectations in financial market : a deterministic HAM approach

The involvement of human behaviors essentially differentiates socio-economic systems and physical systems. Prior to taking actions, individuals form expectations, and constantly update their strategies when outcomes are observed. However in reality, it is people’s aggregate actions rather than individual action that determine the observed outcome, especially in financial market, where people’s expectations and market’s realizations co-evolve with each other. While the self-fulfilling prophecy (the aggregate outcome is consistent with an individual’s expectation) is largely investigated, the self destroying prophecy (the aggregate outcome is inconsistent with an individual’s expectation) has not received the same level of academic scrutiny and acceptance. This paper investigates the self-destroying expectations in financial market using a modified deterministic heterogeneous agent model (HAM) based on Huang et al. (2010), in which agents have two strategies: fundamentalist and chartist. It is found that self-destroying expectations exist in both the general case and crisis scenarios. All simulations have shown the same pattern that a profitable strategy can become unprofitable and results in self-destroying phenomenon when more and more agents exploit it. Empirical evidence is also presented to justify the theoretical model. It is found that real data could reveal a similar pattern as in our simulations. Therefore, our model should at least capture correctly some, if not all, of the underlying self-destroying mechanisms in financial market.Bachelor of Art

Renal Drug Transporters and Drug Interactions.

Transporters in proximal renal tubules contribute to the disposition of numerous drugs. Furthermore, the molecular mechanisms of tubular secretion have been progressively elucidated during the past decades. Organic anions tend to be secreted by the transport proteins OAT1, OAT3 and OATP4C1 on the basolateral side of tubular cells, and multidrug resistance protein (MRP) 2, MRP4, OATP1A2 and breast cancer resistance protein (BCRP) on the apical side. Organic cations are secreted by organic cation transporter (OCT) 2 on the basolateral side, and multidrug and toxic compound extrusion (MATE) proteins MATE1, MATE2/2-K, P-glycoprotein, organic cation and carnitine transporter (OCTN) 1 and OCTN2 on the apical side. Significant drug-drug interactions (DDIs) may affect any of these transporters, altering the clearance and, consequently, the efficacy and/or toxicity of substrate drugs. Interactions at the level of basolateral transporters typically decrease the clearance of the victim drug, causing higher systemic exposure. Interactions at the apical level can also lower drug clearance, but may be associated with higher renal toxicity, due to intracellular accumulation. Whereas the importance of glomerular filtration in drug disposition is largely appreciated among clinicians, DDIs involving renal transporters are less well recognized. This review summarizes current knowledge on the roles, quantitative importance and clinical relevance of these transporters in drug therapy. It proposes an approach based on substrate-inhibitor associations for predicting potential tubular-based DDIs and preventing their adverse consequences. We provide a comprehensive list of known drug interactions with renally-expressed transporters. While many of these interactions have limited clinical consequences, some involving high-risk drugs (e.g. methotrexate) definitely deserve the attention of prescribers