Beam interactions in one-dimensional saturable waveguide arrays

The interaction between two parallel beams in one-dimensional discrete saturable systems has been investigated using lithium niobate nonlinear waveguide arrays. When the beams are separated by one channel and in-phase it is possible to observe soliton fusion at low power levels. This new result is confirmed numerically. By increasing the power, soliton-like propagation of weakly-coupled beams occurs. When the beams are out-of-phase the most interesting result is the existence of oscillations which resemble the recently discovered Tamm oscillations.Comment: 5 pages, 6 figures, submitted to Phys. Rev.

Heating and Trapping of Electrons in ECRIS from Scratch to Afterglow

Plasmas in Electron Cyclotron Resonance Ion Sources (ECRIS) are collisionless and can therefore be simulated by just following the motion of electrons in the confining static magnetic and oscillating microwave (MW) electric field of ECRIS. With a powerful algorithm the three-dimensional trajectories of 104 ECR-heated and confined electrons are calculated in a standard ECRIS with a deep minimum of |B| and a new ECRIS with a very flat minimum of |B|. The spatial electron (plasma) densities and electron energy densities deduced from these trajectories yield new and surprising insight in the performance of ECRIS. With computer animation we plan to present: The energy increase of certain electrons on extremely stable trajectories, the power dependence of the electron energy density up to the X-ray collapse, the time dependent build up of the electron density and energy density distributions, and the time evolution of these electron distributions under afterglow conditions

ClimWood2030, Climate benefits of material substitution by forest biomass and harvested wood products: Perspective 2030 - Final Report

The ClimWood2030 study, commissioned by DG CLIMA of the European Commission, quantifies the five ways in which the EU forest sector contributes to climate change mitigation: carbon sequestration and storage in EU forests, carbon storage in harvested wood products in the EU, substitution of wood products for functionally equivalent materials and substitution of wood for other sources of energy, and displacement of emissions from forests outside the EU. It also explores through scenario analysis, based on a series of interlocking models (GLOBIOM, G4M and WoodCarbonMonitor), along with detailed analysis of Forest Based Functional Units, based on life cycle assessment (LCA), the consequences for GHG balances of policy choices at present under consideration. The focus is on the EU-28, but GHG balances for other parts of the world are also considered, notably to assess consequences of EU policy choices for other regions. The five scenarios are (I) The ClimWood2030 reference scenario, (II) Increase carbon stock in existing EU forests, (III) Cascade use – increase recovery of solid wood products, (IV) Cascade use – prevent first use of biomass for energy and (V) Strongly increase material wood use. The study presents detailed scenario results for key parameters, the policy instruments linked to the scenarios, and main conclusions

Temperature Dependence of the FIR Reflectance of LaSrGaO4

The reflectance of single crystal LaSrGaO4 has been measured from approx 50 to 40000 cm^-1 along the "a" and "c" axis. The optical properties have been calculated from a Kramers-Kronig analysis of the reflectance for both polarizations. The reflectance curves have been fit using a product of Lorentzian oscillators.Comment: 12 pages including 5 figures and 2 tables. Latex file, Requires elsart.sty file and eps

Saturable discrete vector solitons in one-dimensional photonic lattices

Localized vectorial modes, with equal frequencies and mutually orthogonal polarizations, are investigated both analytically and experimentally in a one-dimensional photonic lattice with saturable nonlinearity. It is shown that these modes may span over many lattice elements and that energy transfer among the two components is both phase and intensity dependent. The transverse electrically polarized mode exhibits a single-hump structure and spreads in cascades in saturation, while the transverse magnetically polarized mode exhibits splitting into a two-hump structure. Experimentally such discrete vector solitons are observed in lithium niobate lattices for both coherent and mutually incoherent excitations.Comment: 4 pages, 5 figures (reduced for arXiv

Eccentric binary black holes: Comparing numerical relativity and small mass-ratio perturbation theory

The modelling of unequal mass binary black hole systems is of high importanceto detect and estimate parameters from these systems. Numerical relativity (NR)is well suited to study systems with comparable component masses, m_1\simm_2, whereas small mass ratio (SMR) perturbation theory applies to binarieswhere $q=m_2/m_1as a function of mass ratio for eccentric non-spinning binary black holes. Weproduce$52$NR simulations with mass ratios between$1:10$and$1:1$andinitial eccentricities up to$0.7$. From these we extract quantities likegravitational wave energy and angular momentum fluxes and periastron advance,and assess their accuracy. To facilitate comparison, we develop tools to mapbetween NR and SMR inspiral evolutions of eccentric binary black holes. Wederive post-Newtonian accurate relations between different definitions ofeccentricity. Based on these analyses, we introduce a new definition ofeccentricity based on the (2,2)-mode of the gravitational radiation, whichreduces to the Newtonian definition of eccentricity in the Newtonian limit.From the comparison between NR simulations and SMR results, we quantify theunknown next-to-leading order SMR contributions to the gravitational energy andangular momentum fluxes, and periastron advance. We show that in the comparablemass regime these contributions are subdominant and higher order SMRcontributions are negligible.<br

Extending PT symmetry from Heisenberg algebra to E2 algebra

The E2 algebra has three elements, J, u, and v, which satisfy the commutation relations [u,J]=iv, [v,J]=-iu, [u,v]=0. We can construct the Hamiltonian H=J^2+gu, where g is a real parameter, from these elements. This Hamiltonian is Hermitian and consequently it has real eigenvalues. However, we can also construct the PT-symmetric and non-Hermitian Hamiltonian H=J^2+igu, where again g is real. As in the case of PT-symmetric Hamiltonians constructed from the elements x and p of the Heisenberg algebra, there are two regions in parameter space for this PT-symmetric Hamiltonian, a region of unbroken PT symmetry in which all the eigenvalues are real and a region of broken PT symmetry in which some of the eigenvalues are complex. The two regions are separated by a critical value of g.Comment: 8 pages, 7 figure

From the Feynman-Schwinger representation to the non-perturbative relativistic bound state interaction

We write the 4-point Green function in QCD in the Feynman-Schwinger representation and show that all the dynamical information are contained in the Wilson loop average. We work out the QED case in order to obtain the usual Bethe-Salpeter kernel. Finally we discuss the QCD case in the non-perturbative regime giving some insight in the nature of the interaction kernel.Comment: 25 pages, RevTex, 3 figures included, typos corrected, to appear in Phys. Rev. D 5

Eccentric binary black holes: Comparing numerical relativity and small mass-ratio perturbation theory

The modelling of unequal mass binary black hole systems is of high importance to detect and estimate parameters from these systems. Numerical relativity (NR) is well suited to study systems with comparable component masses, $m_1\sim m_2$, whereas small mass ratio (SMR) perturbation theory applies to binaries where $q=m_2/m_1<< 1$. This work investigates the applicability for NR and SMR as a function of mass ratio for eccentric non-spinning binary black holes. We produce $52$ NR simulations with mass ratios between $1:10$ and $1:1$ and initial eccentricities up to $0.7$. From these we extract quantities like gravitational wave energy and angular momentum fluxes and periastron advance, and assess their accuracy. To facilitate comparison, we develop tools to map between NR and SMR inspiral evolutions of eccentric binary black holes. We derive post-Newtonian accurate relations between different definitions of eccentricity. Based on these analyses, we introduce a new definition of eccentricity based on the (2,2)-mode of the gravitational radiation, which reduces to the Newtonian definition of eccentricity in the Newtonian limit. From the comparison between NR simulations and SMR results, we quantify the unknown next-to-leading order SMR contributions to the gravitational energy and angular momentum fluxes, and periastron advance. We show that in the comparable mass regime these contributions are subdominant and higher order SMR contributions are negligible