Defence and space expenditures in the US: An inter-firm analysis

The economic impact of defence and space expenditures has been an important policy issue because of the secondary benefits expected to be accruing from it. Although defence and space activities can stimulate the early development of many technologies, the lasting economic impact of these technologies is difficult to measure. To capture the scientific and technological values added of defence and space financed productions, we have depended on the patents and scientific and technical publications as the indicators. The economic performance has been measured by two separate indicators: (a) firm growth in terms of average annual rate of change in the number of employees, and (b) rate of return on sales measured by the company's net profits in relation to sales. From 1970-75 and 1980-85 the weight within the manufacturing sector of both defence contractors and the civilian companies increased. Defence firms gained considerably in terms of sales, employment, gross plants and company funded R&D in the latter period under the Reagan Administration. Whereas this may be considered a Reagan effect in defence procurement, other indicators point to in the opposite direction: (a) decrease in the shares of defence R&D contracts, (b) relatively low growth of patent output as percent of total manufacturing from the defence firms, and (c) decrease in scientific publications from defence firms per 1000 employees. Firm level analysis showed that military R&D contracts did not contribute to economic or technical efficiency. Space expenditure did not contribute to improvement of economic performance as measured by company growth and profitability. NASA contracts were not associated with technical progress measured by patents, but they improved scientific publications. Defence expenditures are not of importance for the overall economic efficiency. The standard financial variables, capital formation and own R&D activities prove mostly relevant. The study is restricted to an efficiency analysis in a cross sectional comparison and does not include the effect of market structure.

Enhanced electron correlations, local moments, and Curie temperature in strained MnAs nanocrystals embedded in GaAs

We have studied the electronic structure of hexagonal MnAs, as epitaxial continuous film on GaAs(001) and as nanocrystals embedded in GaAs, by Mn 2p core-level photoemission spectroscopy. Configuration-interaction analyses based on a cluster model show that the ground state of the embedded MnAs nanocrystals is dominated by a d5 configuration that maximizes the local Mn moment. Nanoscaling and strain significantly alter the properties of MnAs. Internal strain in the nanocrystals results in reduced p-d hybridization and enhanced ionic character of the Mn-As bonding interactions. The spatial confinement and reduced p-d hybridization in the nanocrystals lead to enhanced d-electron localization, triggering d-d electron correlations and enhancing local Mn moments. These changes in the electronic structure of MnAs have an advantageous effect on the Curie temperature of the nanocrystals, which is measured to be remarkably higher than that of bulk MnAs.Comment: 4 figures, 2 table

Photon-induced oxidation of graphene/Ir(111) by SO₂ adsorption

We prepare a single layer of graphene oxide by adsorption and subsequent photo-dissociation of SO2 on graphene/Ir(111). Epoxidic oxygen is formed as the main result of this process on graphene, as judged from the appearance of characteristic spectroscopic features in the C 1s and O 1s core level lines. The different stages of decomposition of SO2 into its photo-fragments are examined during the oxidation process. NEXAFS at the carbon K edge reveals a strong disturbance of the graphene backbone after oxidation and upon SO adsorption. The oxide phase is stable up to room temperature, and is fully reversible upon annealing at elevated temperatures. A band gap opening of 330 ± 60 meV between the valence and conduction bands is observed in the graphene oxide phase

Multiphoton entanglement through a Bell multiport beam splitter

Multiphoton entanglement is an important resource for linear optics quantum computing. Here we show that a wide range of highly entangled multiphoton states, including W-states, can be prepared by interfering single photons inside a Bell multiport beam splitter and using postselection. A successful state preparation is indicated by the collection of one photon per output port. An advantage of the Bell multiport beam splitter is that it redirects the photons without changing their inner degrees of freedom. The described setup can therefore be used to generate polarisation, time-bin and frequency multiphoton entanglement, even when using only a single photon source.Comment: 8 pages, 2 figures, carefully revised version, references adde

Entanglement verification for quantum key distribution systems with an underlying bipartite qubit-mode structure

We consider entanglement detection for quantum key distribution systems that use two signal states and continuous variable measurements. This problem can be formulated as a separability problem in a qubit-mode system. To verify entanglement, we introduce an object that combines the covariance matrix of the mode with the density matrix of the qubit. We derive necessary separability criteria for this scenario. These criteria can be readily evaluated using semidefinite programming and we apply them to the specific quantum key distribution protocol.Comment: 6 pages, 2 figures, v2: final versio

The χ2\chi^2 - divergence and Mixing times of quantum Markov processes

We introduce quantum versions of the $\chi^2$-divergence, provide a detailed analysis of their properties, and apply them in the investigation of mixing times of quantum Markov processes. An approach similar to the one presented in [1-3] for classical Markov chains is taken to bound the trace-distance from the steady state of a quantum processes. A strict spectral bound to the convergence rate can be given for time-discrete as well as for time-continuous quantum Markov processes. Furthermore the contractive behavior of the $\chi^2$-divergence under the action of a completely positive map is investigated and contrasted to the contraction of the trace norm. In this context we analyse different versions of quantum detailed balance and, finally, give a geometric conductance bound to the convergence rate for unital quantum Markov processes

MFN status and the choice of tariff regime

The gradualist approach to trade liberalization views the uniform tariffs implied by MFN status as an important step on the path to free trade. We investigate whether a regime of uniform tariffs will be preferable to discriminatory tariffs when countries engage in non-cooperative interaction in multilateral trade. The analysis includes product differentiation and asymmetric costs. We show that with the cost asymmetry the countries will disagree on the choice of tariff regime. When the choice of import tariffs and export subsidies is made sequentially the uniform tariff regime may not be sustainable, because of an incentive to deviate to a discriminatory regime. Hence, an international body is needed to ensure compliance with tariff agreement

Defence and space expenditures in the US: An inter-firm analysis

The economic impact of defence and space expenditures has been an important policy issue because of the secondary benefits expected to be accruing from it. Although defence and space activities can stimulate the early development of many technologies, the lasting economic impact of these technologies is difficult to measure. To capture the scientific and technological values added of defence and space financed productions, we have depended on the patents and scientific and technical publications as the indicators. The economic performance has been measured by two separate indicators: (a) firm growth in terms of average annual rate of change in the number of employees, and (b) rate of return on sales measured by the company's net profits in relation to sales. From 1970-75 and 1980-85 the weight within the manufacturing sector of both defence contractors and the civilian companies increased. Defence firms gained considerably in terms of sales, employment, gross plants and company funded R&D in the latter period under the Reagan Administration. Whereas this may be considered a Reagan effect in defence procurement, other indicators point to in the opposite direction: (a) decrease in the shares of defence R&D contracts, (b) relatively low growth of patent output as percent of total manufacturing from the defence firms, and (c) decrease in scientific publications from defence firms per 1000 employees. Firm level analysis showed that military R&D contracts did not contribute to economic or technical efficiency. Space expenditure did not contribute to improvement of economic performance as measured by company growth and profitability. NASA contracts were not associated with technical progress measured by patents, but they improved scientific publications. Defence expenditures are not of importance for the overall economic efficiency. The standard financial variables, capital formation and own R&D activities prove mostly relevant. The study is restricted to an efficiency analysis in a cross sectional comparison and does not include the effect of market structure