An image analysis toolbox for high-throughput C. elegans assays

We present a toolbox for high-throughput screening of image-based Caenorhabditis elegans phenotypes. The image analysis algorithms measure morphological phenotypes in individual worms and are effective for a variety of assays and imaging systems. This WormToolbox is available through the open-source CellProfiler project and enables objective scoring of whole-worm high-throughput image-based assays of C. elegans for the study of diverse biological pathways that are relevant to human disease.National Institutes of Health (U.S.) (U54 EB005149

Multiplication of microbes below 0.690 water activity: implications for terrestrial and extraterrestrial life

Since a key requirement of known life-forms is available water (water-activity; aw), searches for signatures of past life in terrestrial and extraterrestrial environments have recently targeted places known to have contained significant quantities of biologically available water. The lower limit of water activity that enables cell division is ~0.605 which, until now, was only known to be exhibited by a single eukaryote; the sugar-tolerant, fungal xerophile Xeromyces bisporus. The first forms of life on Earth were, however, prokaryotic. Furthermore, early life on Earth inhabited high-salt environments, suggesting an ability to withstand low water activity. Recent evidence indicates that some halophilic Archaea and Bacteria have water activity limits more or less equal to those of X. bisporus. Regardless of species, cellular systems are sensitive to minute differences in water activity (of w-units) so there is a need to determine water-activity values to three decimal places. We discuss water activity in relation to the limits of Earth’s present-day biosphere; the possibility of microbial multiplication by utilizing water from thin, aqueous films or non-liquid sources; whether prokaryotes were the first organisms able to multiply at the 0.605-aw limit; and whether extraterrestrial aqueous milieu of ≥0.605 aw can resemble fertile microbial habitats found on Earth

Organization design

This paper attempts to explain organization structure based on optimal coordination of interactions among activities. The main idea is that each manager is capable of detecting and coordinating interactions only within his limited area of expertise. Only the CEO can coordinate company-wide interactions. The optimal design of the organization trades off the costs and benefits of various configurations of managers. Our results consist of classifying the characteristics of activities and managerial costs that lead to the matrix organization, the functional hierarchy, the divisional hierarchy, or a flat hierarchy. We also investigate the effect of changing the fixed and variable costs of managers on the nature of the optimal organization, including the extent of centralization

Capital Structure and the Informational Role of Debt.

This paper provides a theory of capital structure based on the effect of debt on investors' information about the firm and on their ability to oversee management. The authors postulate that managers are reluctant to relinquish control and unwilling to provide information that could result in such an outcome. Debt is a disciplining device because default allows creditors the option to force the firm into liquidation and generates information useful to investors. The authors characterize the time path of the debt level and obtain comparative statics results on the debt level, bond yield, probability of default, probability of reorganization, etc. Copyright 1990 by American Finance Association.

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We extend the traditional view of corporate boards as monitors to include a role for outside board members as suppliers of expertise or information. Indeed, both outsiders and insiders may have private information relevant to the decision. Because of the agency problem between managers and owners (who are assumed to be represented by the outside directors), neither party will communicate his or her information fully to the other. Outsiders in our model control agency problems by making some decisions themselves. When they do, the refusal of insiders to communicate their information fully becomes costly. Therefore, shareholders can sometimes be better off by having boards controlled by insiders. We characterize whether the board is optimally controlled by insiders or outsiders, the optimal number of outsiders, and resulting profits as functions of the importance of insiders ’ and outsiders’ information, the extent of agency problems, and some other factors. This leads to an endogenous relationship between profits and the number of outside directors that furthers our understanding of some documented empirical regularities