Industrielle Innovationszyklen und sozial-ökologische Problemlagen:eine Sondierungsstudie zum Wandel von Nutzungskonkurrenzen und Umweltkonflikten unter Bedingungen der "Wissensgesellschaft"

Das Forschungsvorhaben stellt eine Sondierungsstudie zum Thema 'Industrielle Innovationszyklen und sozial-ökologische Problemlagen' dar, bei der im Rahmen einer Literaturanalyse der derzeitige Forschungsstand eruiert, seine Stärken und Schwächen analysiert und Empfehlungen für zukünftige Forschungsfragestellungen gegeben wurden. Zu den Stärken des bisherigen Forschungsstandes gehören die systematische Bezugsetzung von Innovationsfolgen zu den Zusammenhängen von Umwelt und Gesellschaft sowie die Möglichkeit der Einbeziehung der gesellschaftswissenschaftlichen Technik- und Risikoforschung in die Nachhaltigkeitsforschung. Zu den Schwächen des bisherigen Forschungsstandes gehören neben der unzureichenden Integration von Nutzungskonkurrenzen und Verteilungskonflikten in einen systematischen ökologisch-sozialwissenschaftlichen Ansatz vor allem die fehlende analytische Berücksichtigung eines sich abzeichnenden Übergangs zu einem neuen industriellen Innovationszyklus im Rahmen eines sozial-ökologischen Forschungsansatzes sowie das beträchtliche Defizit auf den Gebieten der Industrie- und Innovationsforschung. Zukünftiger Forschungsbedarf wird vor allem in den Bereichen eines Vergleichs der empirischen Verläufe und Folgen vergangener Innovationszyklen, einer Analyse gegenwärtiger Innovationswellen und einer generellen Analyse struktureller und dynamischer Muster sozial-ökologischer Transformationsprozesse gesehen.<br

Surface acoustic waves for acousto-optic modulation in buried silicon nitride waveguides

We theoretically investigate the use of Rayleigh surface acoustic waves (SAWs) for refractive index modulation in optical waveguides consisting of amorphous dielectrics. Considering low-loss Si 3 N 4 waveguides with a standard core cross section of 4.4× 0.03 μ m 2 size, buried 8 μ m deep in a SiO 2 cladding we compare surface acoustic wave generation in various different geometries via a piezo-active, lead zirconate titanate film placed on top of the surface and driven via an interdigitized transducer (IDT). Using numerical solutions of the acoustic and optical wave equations, we determine the strain distribution of the SAW under resonant excitation. From the overlap of the acoustic strain field with the optical mode field we calculate and maximize the attainable amplitude of index modulation in the waveguide. For the example of a near-infrared wavelength of 840 nm, a maximum shift in relative effective refractive index of 0.7x10 −3 was obtained for TE polarized light, using an IDT period of 30 - 35 μ m, a film thickness of 2.5 - 3.5 μ m, and an IDT voltage of 10 V. For these parameters, the resonant frequency is in the range 70 - 85 MHz. The maximum shift increases to 1.2x10 −3 , with a corresponding resonant frequency of 87 MHz, when the height of the cladding above the core is reduced to 3 μ m. The relative index change is about 300-times higher than in previous work based on non-resonant proximity piezo-actuation, and the modulation frequency is about 200-times higher. Exploiting the maximum relative index change of 1.2× 10 −3 in a low-loss balanced Mach-Zehnder modulator should allow full-contrast modulation in devices as short as 120 μ m (half-wave voltage length product = 0.24 Vcm)

The quantum structure of spacetime at the Planck scale and quantum fields

We propose uncertainty relations for the different coordinates of spacetime events, motivated by Heisenberg's principle and by Einstein's theory of classical gravity. A model of Quantum Spacetime is then discussed where the commutation relations exactly implement our uncertainty relations. We outline the definition of free fields and interactions over QST and take the first steps to adapting the usual perturbation theory. The quantum nature of the underlying spacetime replaces a local interaction by a specific nonlocal effective interaction in the ordinary Minkowski space. A detailed study of interacting QFT and of the smoothing of ultraviolet divergences is deferred to a subsequent paper. In the classical limit where the Planck length goes to zero, our Quantum Spacetime reduces to the ordinary Minkowski space times a two component space whose components are homeomorphic to the tangent bundle TS^2 of the 2-sphere. The relations with Connes' theory of the standard model will be studied elsewhere.Comment: TeX, 37 pages. Since recent and forthcoming articles (hep-th/0105251, hep-th/0201222, hep-th/0301100) are based on this paper, we thought it would be convenient for the readers to have it available on the we

Solid-phase synthesis of duocarmycin analogues and the effect of C-terminal substitution on biological activity

YesThe duocarmycins are potent antitumour agents with potential in the development of antibody drug conjugates (ADCs) as well as being clinical candidates in their own right. In this paper, we describe the synthesis of a duocarmycin monomer (DSA) that is suitably protected for utilisation in solid phase synthesis. The synthesis was performed on a large scale and the resulting racemic protected Fmoc-DSA subunit was separated by supercritical fluid chromatography (SFC) into the single enantiomers. Application to solid phase synthesis methodology gave a series of monomeric and extended duocarmycin analogues with amino acid substituents. The DNA sequence selectivity was similar to previous reports for both the monomeric and extended compounds. The substitution at the C-terminus of the duocarmycin caused a decrease in antiproliferative activity for all of the compounds studied. An extended compound containing an alanine at the C-terminus was converted to the primary amide or to an extended structure containing a terminal tertiary amine but this had no beneficial effects on biological activity.MJS was funded by Novartis and UEA. We thank the EPSRC Mass Spectrometry Service, Swansea. We thank Richard Robinson and Julia Hatto at Novartis for help in the large scale synthesis

Polarization correlations for electron-impact excitation of the resonant transitions of Ne and Ar at low incident energies

The electron-polarized-photon coincidence method is used to determine linear and circular polarization correlations in vacuum ultraviolet (VUV) for the differential electron-impact excitation of neon and argon resonance transitions at impact energies of 25 and 30 eV at small scattering angles up to 40. The circular polarization correlation is found to be positive in the case of Ne at 25 eV and supports the prediction of the present B-spline R-matrix theory concerning the violation of a long-established propensity rule regarding angular momentum transfer in electron-impact excitation of S→P transitions. Comparisons with the results from the present relativistic distorted-wave approximation and an earlier semirelativistic distorted-wave Born model are also made. For the case of Ar, at 25 and 30 eV, the circular polarization measurements remain in agreement with theory, but provide limited evidence as to whether or not the circular polarization at small scattering angles is also positive. For the linear polarizations, much better agreement with theory is obtained than in earlier measurements carried out by S. H. Zheng and K. Becker

Statistics of Coulomb Blockade Peak Spacings within the Hartree-Fock Approximation

We study the effect of electronic interactions on the addition spectra and on the energy level distributions of two-dimensional quantum dots with weak disorder using the self-consistent Hartree-Fock approximation for spinless electrons. We show that the distribution of the conductance peak spacings is Gaussian with large fluctuations that exceed, in agreement with experiments, the mean level spacing of the non-interacting system. We analyze this distribution on the basis of Koopmans' theorem. We show furthermore that the occupied and unoccupied Hartree-Fock levels exhibit Wigner-Dyson statistics.Comment: 5 pages, 2 figures, submitted for publicatio

Worldline Monte Carlo for fermion models at large N_f

Strongly-coupled fermionic systems can support a variety of low-energy phenomena, giving rise to collective condensation, symmetry breaking and a rich phase structure. We explore the potential of worldline Monte Carlo methods for analyzing the effective action of fermionic systems at large flavor number N_f, using the Gross-Neveu model as an example. Since the worldline Monte Carlo approach does not require a discretized spacetime, fermion doubling problems are absent, and chiral symmetry can manifestly be maintained. As a particular advantage, fluctuations in general inhomogeneous condensates can conveniently be dealt with analytically or numerically, while the renormalization can always be uniquely performed analytically. We also critically examine the limitations of a straightforward implementation of the algorithms, identifying potential convergence problems in the presence of fermionic zero modes as well as in the high-density region.Comment: 40 pages, 13 figure

Proximity effects and characteristic lengths in ferromagnet-superconductor structures

We present an extensive theoretical investigation of the proximity effects that occur in Ferromagnet/Superconductor ($F/S$) systems. We use a numerical method to solve self consistently the Bogoliubov-de Gennes equations in the continuum. We obtain the pair amplitude and the local density of states (DOS), and use these results to extract the relevant lengths characterizing the leakage of superconductivity into the magnet and to study spin splitting into the superconductor. These phenomena are investigated as a function of parameters such as temperature, magnet polarization, interfacial scattering, sample size and Fermi wavevector mismatch, all of which turn out to have important influence on the results. These comprehensive results should help characterize and analyze future data and are shown to be in agreement with existing experiments.Comment: 24 pages, including 26 figure