Motives for corporate cash holdings:the CEO optimism effect

We examine the chief executive officer (CEO) optimism effect on managerial motives for cash holdings and find that optimistic and non-optimistic managers have significantly dissimilar purposes for holding more cash. This is consistent with both theory and evidence that optimistic managers are reluctant to use external funds. Optimistic managers hoard cash for growth opportunities, use relatively more cash for capital expenditure and acquisitions, and save more cash in adverse conditions. By contrast, they hold fewer inventories and receivables and their precautionary demand for cash holdings is less than that of non-optimistic managers. In addition, we consider debt conservatism in our model and find no evidence that optimistic managers’ cash hoarding is related to their preference to use debt conservatively. We also document that optimistic managers hold more cash in bad times than non-optimistic managers do. Our work highlights the crucial role that CEO characteristics play in shaping corporate cash holding policy

Functional Analysis of the Leading Malaria Vaccine Candidate AMA-1 Reveals an Essential Role for the Cytoplasmic Domain in the Invasion Process

A key process in the lifecycle of the malaria parasite Plasmodium falciparum is the fast invasion of human erythrocytes. Entry into the host cell requires the apical membrane antigen 1 (AMA-1), a type I transmembrane protein located in the micronemes of the merozoite. Although AMA-1 is evolving into the leading blood-stage malaria vaccine candidate, its precise role in invasion is still unclear. We investigate AMA-1 function using live video microscopy in the absence and presence of an AMA-1 inhibitory peptide. This data reveals a crucial function of AMA-1 during the primary contact period upstream of the entry process at around the time of moving junction formation. We generate a Plasmodium falciparum cell line that expresses a functional GFP-tagged AMA-1. This allows the visualization of the dynamics of AMA-1 in live parasites. We functionally validate the ectopically expressed AMA-1 by establishing a complementation assay based on strain-specific inhibition. This method provides the basis for the functional analysis of essential genes that are refractory to any genetic manipulation. Using the complementation assay, we show that the cytoplasmic domain of AMA-1 is not required for correct trafficking and surface translocation but is essential for AMA-1 function. Although this function can be mimicked by the highly conserved cytoplasmic domains of P. vivax and P. berghei, the exchange with the heterologous domain of the microneme protein EBA-175 or the rhoptry protein Rh2b leads to a loss of function. We identify several residues in the cytoplasmic tail that are essential for AMA-1 function. We validate this data using additional transgenic parasite lines expressing AMA-1 mutants with TY1 epitopes. We show that the cytoplasmic domain of AMA-1 is phosphorylated. Mutational analysis suggests an important role for the phosphorylation in the invasion process, which might translate into novel therapeutic strategies

Demanda mediana por serviços públicos e desempenho eleitoral: evidências do modelo do eleitor mediano para os municípios brasileiros

O objetivo deste trabalho é testar empiricamente a validade do modelo do eleitor mediano para o caso brasileiro. O teste foi viabilizado pela possibilidade de reeleição, estabelecida em 1997 por meio da Emenda da Reeleição. Com informações municipais do Censo Populacional e do TSE para o ano de 2000, identificaram-se as cestas ofertadas por candidatos à reeleição como os gastos efetuados durante seus primeiros mandatos. Em seguida, estimou-se a demanda por serviços públicos locais. Relaxando a hipótese de informação perfeita dos candidatos em relação à demanda mediana, e impondo uma hipótese menos forte, de expectativas racionais, justificou-se a estimação de uma medida de erro de percepção dos candidatos à reeleição em relação à demanda mediana. Em seguida, estimou-se o impacto do módulo dessa medida sobre o desempenho eleitoral dos candidatos à reeleição usando modelos de seleção. O resultado obtido sugere que o modelo do eleitor mediano é válido para os municípios brasileiros