Einstein equations for an asymmetric brane-world

We consider a brane-world of co-dimension one without the reflection symmetry that is commonly imposed between the two sides of the brane. Using the coordinate-free formalism of the Gauss-Codacci equations, we derive the effective Einstein equations by relating the local curvature to the matter on the brane in the case when its bare tension is much larger than the localized matter, and hence show that Einstein gravity is a natural consequence of such models in the weak field limit. We find agreement with the recently derived cosmological case, which can be solved exactly, and point out that such models can be realized naturally in the case where there is a minimally coupled form field in the bulk.Comment: 14 pages, Revte

Alternative Splicing in the Differentiation of Human Embryonic Stem Cells into Cardiac Precursors

The role of alternative splicing in self-renewal, pluripotency and tissue lineage specification of human embryonic stem cells (hESCs) is largely unknown. To better define these regulatory cues, we modified the H9 hESC line to allow selection of pluripotent hESCs by neomycin resistance and cardiac progenitors by puromycin resistance. Exon-level microarray expression data from undifferentiated hESCs and cardiac and neural precursors were used to identify splice isoforms with cardiac-restricted or common cardiac/neural differentiation expression patterns. Splice events for these groups corresponded to the pathways of cytoskeletal remodeling, RNA splicing, muscle specification, and cell cycle checkpoint control as well as genes with serine/threonine kinase and helicase activity. Using a new program named AltAnalyze (http://www.AltAnalyze.org), we identified novel changes in protein domain and microRNA binding site architecture that were predicted to affect protein function and expression. These included an enrichment of splice isoforms that oppose cell-cycle arrest in hESCs and that promote calcium signaling and cardiac development in cardiac precursors. By combining genome-wide predictions of alternative splicing with new functional annotations, our data suggest potential mechanisms that may influence lineage commitment and hESC maintenance at the level of specific splice isoforms and microRNA regulation

Should the Outsiders Be Left Out? Director Stock Options, Expectations and Earnings Management

We examine the potential confounding effects that awarding outside directors stock options may have on the quality of financial disclosure. By aligning their interests with those of shareholders, directors should be more inclined to monitor and disclose relevant information to investors. Alternatively, stock options increase directors’ compensation sensitivity to firm performance and thus may motivate collusion with management to misreport for short-term financial gain. Our results support the argument that awarding outside directors with options promotes the dissemination of better information to the analyst community. This is reflected in initial forecast errors that are smaller, contain less variance, and have a greater probability of being accurately revised to meet actual earnings in a timely manner, regardless of whether the initial forecasts are positively or negatively biased. A comparison of director and CEO stock options reveals that CEO options only increase the likelihood of lowering overly optimistic expectations; we find no evidence consistent with CEO options increasing the likelihood of walking up pessimistic expectations. Thus, while performance pay to CEOs promotes the practice of maintaining and meeting low expectations, options to outsiders promotes disclosure regardless of the direction of the bias. We find no evidence to suggest director options increase the likelihood of earnings management. Overall, our results indicate that director stock options indeed provide directors with an incentive to promote shareholder interests, but unlike CEO stock options, do not add significant disclosure related agency costs.N/

The liquidity impact of insider trading on small and medium size enterprises

This study compares the impact of insider trading by corporate employees of small and medium-sized enterprises (SMEs) on the stock price liquidity of these firms with that of larger institutions. Using publicly reported data, we assess how trades placed by SME insiders affect the bid-ask spread of their companies’ stock. We document that the spread gets significantly larger following these transactions relative to trades by insiders from larger firms. Collectively, the evidence suggests that insider trading by SME executives, as well as non-executives, decreases liquidity for their firms. One important implication from our findings is that the cost of insider trading is more severe for SMEs, firms characterized by greater information asymmetry

Environmental Management’s Impact on Market Value: Rewards and Punishments

Concerns regarding changes in the natural environment have led to an increase in research regarding environmental management (EM) practices. Studies examining the financial impact of such practices have been inconclusive. Drawing on agency theory and the resource-based view of the firm, we provide a comprehensive examination of the market’s reaction to firms identified by Newsweek’s Green Rankings as the best (top 100) and worst (bottom 100) for EM reputation among the largest 500 firms in the United States. Specifically, we investigate the extent to which the market reacts differently to service firms and manufacturing firms in regards to environmental reputation signals. We find that the market responds favorably to positive environmental management reputation signals for service firms and to negative environmental management reputation signals for manufacturing firms. Post hoc analysis reveals that both service firms and manufacturing firms are rewarded for being ranked “in the middle” of the Newsweek Green Rankings