Fears of rogue states, withdrawal of cold war-era security guarantees, a falling technological threshold, and availability to terrorist organizations ensure that nuclear weapons proliferation remains a central security issue and that developing an adequate theory of proliferation ranks high on the agenda. A data set on nuclear proliferation is constructed that identifies three different stages on the path to the weaponization of nuclear weapons technology. Hazard models and multinomial logit are used to test theories of nuclear proliferation. Results suggest that nuclear weapons proliferation is strongly associated with the level of economic development, the external threat environment, lack of great-power security guarantees, and a low level of integration in the world economy.Sincetheadventoftheatomicage,nuclearweapons proliferation has been one of the major security issues facing the world. After the end of the cold war, concerns about proliferation have grown rather than subsided: the withdrawal of superpower security guarantees has created incentives for smaller powers to acquire nuclear weapons, a handful of "rogue" states have sought nuclear arms, Pakistan and India have joined the ranks of overt nuclear powers, the technological threshold necessary to develop atomic weapons is in reach of ever more nations, and the possibility of new nuclear powers selling weapons to terrorist organizations has focused concerns. Controversy rages around the world over U.S. plans to build a national missile defense (NMD) system to fend off emerging nuclear threats, and scholars debate whether NMD will fan the fires of proliferation or reduce the incentive for more states to acquire nuclear 859 AUTHORS' NOTE: Thanks to

No abstract

Macrophages are innate immune cells that have a central role in combating infection and maintaining tissue homeostasis. They exhibit remarkable plasticity in response to environmental cues. At either end of a broad activation spectrum are pro-inflammatory (M1) and anti-inflammatory (M2) macrophages with distinct functional and phenotypical characteristics. Macrophages also play a crucial role in orchestrating immune responses to biomaterials used in the fabrication of implantable devices and drug delivery systems. To assess the impact of different surface chemistries on macrophage polarisation, human monocytes were cultured for 6 days on untreated hydrophobic polystyrene (PS) and hydrophilic O2 plasma-etched polystyrene (O2-PS40) surfaces. Our data clearly show that monocytes cultured on the hydrophilic O2-PS40 surface are polarised towards an M1-like phenotype, as evidenced by significantly higher expression of the pro-inflammatory transcription factors STAT1 and IRF5. By comparison, monocytes cultured on the hydrophobic PS surface exhibited an M2-like phenotype with high expression of mannose receptor (MR) and production of the anti-inflammatory cytokines IL-10 and CCL18. While the molecular basis of such different patterns of cell differentiation is yet to be fully elucidated, we hypothesise that it is due to the adsorption of different biomolecules on these surface chemistries. Indeed our surface characterisation data show quantitative and qualitative differences between the protein layers on the O2-PS40 surface compared to PS surface which could be responsible for the observed differential macrophage polarisation on each surface.

The ability of to switch between yeast to hyphal form is a property that is primarily associated with the invasion and virulence of this human pathogenic fungus. Several glycosylphosphatidylinositol (GPI)-anchored proteins are expressed only during hyphal morphogenesis. One of the major pathways that controls hyphal morphogenesis is the Ras-signaling pathway. We examine the cross-talk between GPI anchor biosynthesis and Ras signaling in We show that the first step of GPI biosynthesis is activated by Ras in This is diametrically opposite to what is reported in Of the two Ras proteins, CaRas1 alone activates GPI-GnT activity; activity is further stimulated by constitutively activated CaRas1. CaRas1 localized to the cytoplasm or endoplasmic reticulum (ER) is sufficient for GPI-GnT activation. Of the six subunits of the GPI--acetylglucosaminyltransferase (GPI-GnT) that catalyze the first step of GPI biosynthesis, CaGpi2 is the key player involved in activating Ras signaling and hyphal morphogenesis. Activation of Ras signaling is independent of the catalytic competence of GPI-GnT. This too is unlike what is observed in where multiple subunits were identified as inhibiting Ras2. Fluorescence resonance energy transfer (FRET) studies indicate a specific physical interaction between CaRas1 and CaGpi2 in the ER, which would explain the ability of CaRas1 to activate GPI-GnT. CaGpi2, in turn, promotes activation of the Ras-signaling pathway and hyphal morphogenesis. The mutant is also more susceptible to macrophage-mediated killing, and macrophage cells show better survival when co-cultured with .