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

How do employment tax credits work? : an analysis of the German inheritance tax

Employment tax credit programs have been repeatedly used during economic crises, although their usefulness is empirically contestable. The objective of this paper is to quantify the tax effects of employment tax credit programs. A recent revision of the German inheritance tax law provides an eminent opportunity to analyze the effects caused by such a preferential treatment. The tax liability depends on a company’s future employment expenses. Hence, we use micro-level data of realized business transfers from the German Inheritance Tax Statistic and combine them with a simulation of the future development of employment over the relevant time-horizon. We identify the magnitude of tax reductions granted to business transfers under a preferential treatment. Further, we demonstrate that these reductions are considerably larger in times of economic growth. Our findings also suggest that employment tax credits have pro-cyclical effects and specifically foster transfers between unrelated parties. Finally, the preferential treatment of business transfers does not provide incentives to increase employment

Theoretical investigations of wide-bandgap semiconductor nanowires for optoelectronic applications

Improving existing optoelectronic devices is a crucial step in satisfying humanity's increasing demand for electricity. This work explores different ways to achieve this goal. First density functional theory (DFT) calculations are performed on functionalized ZnO and GaN surface structures to investigate possible changes to their structural, electronic, and optical properties due to the attached functional groups. For both materials, attaching thiol groups leads to intra-gap states, which are found to be optically active for ZnO. Aiming at bigger GaN model sizes in future works compared to standard DFT approaches, a DFTB model was developed for GaN surface nanostructures. The interatomic interaction parameters were validated against standard DFT, achieving acceptable performances on bulk Ga, bulk GaN, and surface GaN systems. Another possible route to modify the electronic properties of semiconductor nanostructures is doping. ZnO bulk was doped with cobalt atoms to model different intrinsic defect complexes. Many-body GW calculations were employed to investigate their electronic structures. One defect complex is identified to be responsible for the experimentally observed photoluminescence. Due to the continuing decrease in size of electronic devices, the standard gate oxide SiO2 needs to be replaced, since today's required film thicknesses expose a crucial weakness of SiO2, a high tunneling leakage current. Possible candidates to be used as a replacement are hafnium silicate nanostructures, that avoid the described weakness. In a first step a density functional-based tight binding (DFTB) model for HfO2 was developed and validated against standard DFT calculations, achieving a very good performance for Hf bulk and HfO2 bulk. The obtained parameters were then used in a MD study on amorphous HfO2 systems to discuss their structural and electronic properties. In a second step this model was extended by silicon and applied to amorphous hafnium silicate structures to evaluate the influence of different Hf:Si ratios

End of the free lunch? The responses of traditional European airlines to the low-cost carrier threat

The short-haul operations of traditional European airlines such as British Airways and Lufthansa have come under increasing pressure from the growth of low-cost carriers. This paper examines their competitive responses. These are found to include reductions in labour costs, greater use of regional aircraft and a run-down of secondary hubs. Minimum stay requirements on cheap fares have been axed in many markets, while changes to the onboard service and a move to direct-sell bring these airlines closer to the low-cost carrier product. The network strength is largely maintained however, which appears a better strategy than setting up a low-cost subsidiary