Smart Change in Strategy: IBM‘s Response to Challenging Times

International Business Machines, or IBM, has been an indisputable force in the communications industry, leading the world into the modern, global technological age. Currently, IBM has revamped its business paradigm, allocating the majority of its resources to consulting work and data analyses rather than manufacturing as it had done so in the past — for the primary objectives of optimizing existing assets, resolving problems of burgeoning cities and beleaguered governments, and enhancing peoples‘ lives in a sustainable way

The Drosophila Inhibitor of Apoptosis (IAP) DIAP2 Is Dispensable for Cell Survival, Required for the Innate Immune Response to Gram-negative Bacterial Infection, and Can Be Negatively Regulated by the Reaper/Hid/Grim Family of IAP-binding Apoptosis Inducers

Many inhibitor of apoptosis (IAP) family proteins inhibit apoptosis. IAPs contain N-terminal baculovirus IAP repeat domains and a C-terminal RING ubiquitin ligase domain. Drosophila IAP DIAP1 is essential for the survival of many cells, protecting them from apoptosis by inhibiting active caspases. Apoptosis initiates when proteins such as Reaper, Hid, and Grim bind a surface groove in DIAP1 baculovirus IAP repeat domains via an N-terminal IAP-binding motif. This evolutionarily conserved interaction disrupts DIAP1-caspase interactions, unleashing apoptosis-inducing caspase activity. A second Drosophila IAP, DIAP2, also binds Rpr and Hid and inhibits apoptosis in multiple contexts when overexpressed. However, due to a lack of mutants, little is known about the normal functions of DIAP2. We report the generation of diap2 null mutants. These flies are viable and show no defects in developmental or stress-induced apoptosis. Instead, DIAP2 is required for the innate immune response to Gram-negative bacterial infection. DIAP2 promotes cytoplasmic cleavage and nuclear translocation of the NF-{kappa}B homolog Relish, and this requires the DIAP2 RING domain. Increasing the genetic dose of diap2 results in an increased immune response, whereas expression of Rpr or Hid results in down-regulation of DIAP2 protein levels. Together these observations suggest that DIAP2 can regulate immune signaling in a dose-dependent manner, and this can be regulated by IBM-containing proteins. Therefore, diap2 may identify a point of convergence between apoptosis and immune signaling pathways

Heterogeneity and Disorder: Contributions of Rolf Landauer

Rolf Landauer made important contributions to many branches of science. Within the broad area of transport in disordered media, he wrote seminal papers on electrical conduction in macroscopically inhomogeneous materials, as well as fundamental analyses of electron transport in quantum mechanical systems with disorder on the atomic scale. We review here some of these contributions. We also briefly describe some main events in his personal and scientific life.Comment: 10 pages, 3 figures; presented on the occasion when Rolf Landauer was awarded, posthumously, the inaugural ETOPIM Medal at the ETOPIM 8 Conference, which took place during 7--12 June, 2009 in Rethymnon, Cret

The limits of mean-field heterozygosity estimates under spatial extension in simulated plant populations

Computational models of evolutionary processes are increasingly required to incorporate multiple and diverse sources of data. A popular feature to include in population genetics models is spatial extension, which reflects more accurately natural populations than does a mean field approach. However, such models necessarily violate the mean field assumptions of classical population genetics, as do natural populations in the real world. Recently, it has been questioned whether classical approaches are truly applicable to the real world. Individual based models (IBM) are a powerful and versatile approach to achieve integration in models. In this study an IBM was used to examine how populations of plants deviate from classical expectations under spatial extension. Populations of plants that used three different mating strategies were placed in a range of arena sizes giving crowded to sparse occupation densities. Using a measure of population density, the pollen communication distance (Pcd), the deviation exhibited by outbreeding populations differed from classical mean field expectations by less than 5% when Pcd was less than 1, and over this threshold value the deviation significantly increased. Populations with an intermediate mating strategy did not have such a threshold and deviated directly with increasing isolation between individuals. Populations with a selfing strategy were influenced more by the mating strategy than by increased isolation. In all cases pollen dispersal was more influential than seed dispersal. The IBM model showed that mean field calculations can be reasonably applied to natural outbreeding plant populations that occur at a density in which individuals are less than the average pollen dispersal distance from their neighbors