Fiscal Paradise: Foreign Tax Havens and American Business

The offshore tax haven affiliates of American corporations account for more than a quarter of US foreign investment, an nearly a third of the foreign profits of US firms. This paper analyzes the origins of this tax haven activity and its implications for the US and foreign governments. Based on the behavior of US fins in 1982, it appears that American companies report extraordinarily high profit rates on both their real and their financial investments in tax havens. We calculate from this behavior that the tax rate that maximizes tax revenue for a typical haven is around 6%. The revenue implications for the US are more complicated, since tax havens may ultimately enhance the ability of the US government to tax the foreign earnings of American companies.

Paleolakes and lacustrine basins on Mars

The problems of how warm and wet Mars once was and when climate transitions may have occurred are not well understood. Mars may have had an early environment similar to Earth's that was conducive to the emergence of life. In addition, increasing geologic evidence indicates that water, upon which terrestrial life depends, has been present on Mars throughout its history. This evidence does not detract from the possibility that life may have originated on early Mars, but rather suggests that life could have developed over longer periods of time in longer lasting, more clement local environments than previously envisioned. It is suggested herein that such environments may have been provided by paleolakes, located mostly in the northern lowlands and probably ice covered. Such lakes probably would have had diverse origins. Glacial lakes may have occupied ice eroded hollows or formed in valleys obstructed by moraines or ice barriers. Unlike Earth, the Martian record of the origin and evolution of possible life may have not been erased by extensive deformation of the surface. Thus the basins that may have contained the paleolakes are potential sites for future biological, geological, and climatological study

Magnetic Response in the Underdoped Cuprates

We examine the dynamical magnetic response of the underdoped cuprates by employing a phenomenological theory of a doped resonant valence bond state where the Fermi surface is truncated into four pockets. This theory predicts a resonant spin response which with increasing energy (0 to 100meV) appears as an hourglass. The very low energy spin response is found at (pi,pi +- delta) and (pi +- delta,pi) and is determined by scattering from the pockets' frontside to the tips of opposite pockets where a van Hove singularity resides. At energies beyond 100 meV, strong scattering is seen from (pi,0) to (pi,pi). This theory thus provides a semi-quantitative description of the spin response seen in both INS and RIXS experiments at all relevant energy scales

Sindbis virus proteins nsP1 and nsP2 contain homology to nonstructural proteins from several RNA plant viruses

Although the genetic organization of tobacco mosaic virus (TMV) differs considerably from that of the tripartite viruses (alfalfa mosaic virus [AlMV] and brome mosaic virus [BMV]), all of these RNA plant viruses share three domains of homology among their nonstructural proteins. One such domain, common to the AlMV and BMV 2a proteins and the readthrough portion of TMV p183, is also homologous to the readthrough protein nsP4 of Sindbis virus (Haseloff et al., Proc. Natl. Acad. Sci. U.S.A. 81:4358-4362, 1984). Two more domains are conserved among the AlMV and BMV 1a proteins and TMV p126. We show here that these domains have homology with portions of the Sindbis proteins nsP1 and nsP2, respectively. These results strengthen the view that the four viruses share mechanistic similarities in their replication strategies and may be evolutionarily related. These results also suggest that either the AlMV 1a, BMV 1a, and TMV p126 proteins are multifunctional or Sindbis proteins nsP1 and nsP2 function together as subunits in a single complex

Expression of Sindbis virus structural proteins via recombinant vaccinia virus: synthesis, processing, and incorporation into mature Sindbis virions

We have obtained a vaccinia virus recombinant which contains a complete cDNA copy of the 26S RNA of Sindbis virus within the thymidine kinase gene of the vaccinia virus genome. This recombinant constitutively transcribed the Sindbis sequences throughout the infectious cycle, reflecting the dual early-late vaccinia promoter used in this construction. The Sindbis-derived transcripts were translationally active, giving rise to both precursor and mature structural proteins of Sindbis virus, including the capsid protein (C), the precursor of glycoprotein E2 (PE2), and the two mature envelope glycoproteins (E1 and E2). These are the same products translated from the 26S mRNA during Sindbis infection, and thus these proteins were apparently cleaved, glycosylated, and transported in a manner analogous to that seen during authentic Sindbis infections. By using epitope-specific antibodies, it was possible to demonstrate that recombinant-derived proteins were incorporated into Sindbis virions during coinfections with monoclonal antibody-resistant Sindbis variants. These results suggest that all the information necessary to specify the proper biogenesis of Sindbis virus structural proteins resides within the 26S sequences and that vaccinia may provide an appropriate system for using DNA molecular genetic manipulations to unravel a variety of questions pertinent to RNA virus replication

Neomycin resistance as a dominant selectable marker for selection and isolation of vaccinia virus recombinants

The antibiotic G418 was shown to be an effective inhibitor of vaccinia virus replication when an appropriate concentration of it was added to cell monolayers 48 h before infection. Genetic engineering techniques were used in concert with DNA transfection protocols to construct vaccinia virus recombinants containing the neomycin resistance gene (neo) from transposon Tn5. These recombinants contained the neo gene linked in either the correct or incorrect orientation relative to the vaccinia virus 7.5-kilodalton gene promoter which is expressed constitutively throughout the course of infection. The vaccinia virus recombinant containing the chimeric neo gene in the proper orientation was able to grow and form plaques in the presence of G418, whereas both the wild-type and the recombinant virus with the neo gene in the opposite polarity were inhibited by more than 98%. The effect of G418 on virus growth may be mediated at least in part by selective inhibition of the synthesis of a subset of late viral proteins. These results are discussed with reference to using this system, the conferral of resistance to G418 with neo as a positive selectable marker, to facilitate constructing vaccinia virus recombinants which contain foreign genes of interest

Photon Statistics of a Single Atom Laser

We consider a laser model consisting of a single four-level or three-level atom, an optical cavity, and an incoherent pump. Results for photon statistics for varying pump levels are obtained using a quantum trajectory algorithm. In particular, we calculate the mean photon number, Fano factor (which is the variance over the mean). We examine that the behavior of the single-atom device as β, the fraction of spontaneous emission into the lasing mode, is varied. Typical values considered for β are 0.01\u3cβ\u3c1.0. We find that for large enough β, lasing action, with properties similar to those predicted by semiclassical theories that factorize atom-field correlations and use a small-noise approximation, can occur. Squeezing can occur as β is increased. There is no evidence of a sharp phase transition from weakly excited thermal light to coherent light at a particular pump power. This is consistent with work on many-atom lasers with β values in the range considered here. As β is increased, the output goes from quasithermal light to coherent and finally to squeezed light, progressing into a fully quantum-mechanical regime. We also consider the effects of cavity damping and spontaneous emission rates on these results

Sindbis virus ts103 has a mutation in glycoprotein E2 that leads to defective assembly of virions

Sindbis virus mutant ts103 is aberrant in the assembly of virus particles. During virus budding, proper nucleocapsid-glycoprotein interactions fail to occur such that particles containing many nucleocapsids are formed, and the final yield of virus is low. We have determined that a mutation in the external domain of glycoprotein E2, Ala-344-->Val, is the change that leads to this phenotype. Mapping was done by making recombinant viruses between ts103 and a parental strain of the virus, using a full-length cDNA clone of Sindbis virus from which infectious RNA can be transcribed, together with sequence analysis of the region of the genome shown in this way to contain the ts103 lesion. A partial revertant of ts103, called ts103R, was also mapped and sequenced and found to be a second-site revertant in which a change in glycoprotein E1 from lysine to methionine at position 227 partially suppresses the phenotypic effects of the change at E2 position 344. An analysis of revertants from ts103 mutants in which the Ala-->Val change had been transferred into a defined background showed that pseudorevertants were more likely to arise than were true revertants and that the ts103 change itself reverted very infrequently. The assembly defect in ts103 appeared to result from weakened interactions between the virus membrane glycoproteins or between these glycoproteins and the nucleocapsid during budding. Both the E2 mutation leading to the defect in virus assembly and the suppressor mutation in glycoprotein E1 are in the domains external to the lipid bilayer and thus in domains that cannot interact directly with the nucleocapsid. This suggests that in ts103, either the E1-E2 heterodimers or the trimeric spikes (consisting of three E1-E2 heterodimers) are unstable or have an aberrant configuration, and thus do not interact properly with the nucleocapsid, or cannot assembly correctly to form the proper icosahedral array on the surface of the virus

Earthquake Slip Between Dissimilar Poroelastic Materials

A mismatch of elastic properties across a fault induces normal stress changes during spatially nonuniform in-plane slip. Recently, Rudnicki and Rice showed that similar effects follow from a mismatch of poroelastic properties (e.g., permeability) within fluid-saturated fringes of damaged material along the fault walls; in this case, it is pore pressure on the slip plane and hence effective normal stress that is altered during slip. The sign of both changes can be either positive or negative, and they need not agree. Both signs reverse when rupture propagates in the opposite direction. When both elastic and poroelastic properties are discontinuous across the fault, steady sliding at a constant friction coefficient, f, is unstable for arbitrarily small f if the elastic mismatch permits the existence of a generalized Rayleigh wave. Spontaneous earthquake rupture simulations on regularized slip-weakening faults confirm that the two effects have comparable magnitudes and that the sign of the effective normal stress change cannot always be predicted solely from the contrast in elastic properties across the fault. For opposing effects, the sign of effective normal stress change reverses from that predicted by the poroelastic mismatch to that predicted by the elastic mismatch as the rupture accelerates, provided that the wave speed contrast exceeds about 5–10% (the precise value depends on the poroelastic contrast and Skempton's coefficient). For faults separating more elastically similar materials, there exists a minimum poroelastic contrast above which the poroelastic effect always determines the sign of the effective normal stress change, no matter the rupture speed.Earth and Planetary SciencesEngineering and Applied Science

Snow and ice melt flow features on Devon Island, Nunavut, Arctic Canada as possible analogs for recent slope flow features on Mars

Based on morphologic and contextual analogs from Devon Island, Arctic Canada, the recent martian slope flow features reported by Malin and Edgett are reinterpreted as being due not necessarily to groundwater seepage but possibly to snow or ice melt