New perturbative solutions of the Kerr-Newman dilatonic black hole field equations

This work describes new perturbative solutions to the classical, four-dimensional Kerr--Newman dilaton black hole field equations. Our solutions do not require the black hole to be slowly rotating. The unperturbed solution is taken to be the ordinary Kerr solution, and the perturbation parameter is effectively the square of the charge-to-mass ratio $(Q/M)^2$ of the Kerr--Newman black hole. We have uncovered a new, exact conjugation (mirror) symmetry for the theory, which maps the small coupling sector to the strong coupling sector ($\phi \to -\phi$). We also calculate the gyromagnetic ratio of the black hole.Comment: Revtex, 27 page

Seismic topographic scattering in the context of GW detector site selection

In this paper, we present a calculation of seismic scattering from irregular surface topography in the Born approximation. Based on US-wide topographic data, we investigate topographic scattering at specific sites to demonstrate its impact on Newtonian-noise estimation and subtraction for future gravitational-wave detectors. We find that topographic scattering at a comparatively flat site in Oregon would not pose any problems, whereas scattering at a second site in Montana leads to significant broadening of wave amplitudes in wavenumber space that would make Newtonian-noise subtraction very challenging. Therefore, it is shown that topographic scattering should be included as criterion in the site-selection process of future low-frequency gravitational-wave detectors.Comment: 16 pages, 7 figure

High resolution modelling of the North Icelandic Irminger Current (NIIC)

The northward inflow of Atlantic Water through Denmark Strait &ndash; the North Icelandic Irminger Current (NIIC) &ndash; is simulated with a numerical model of the North Atlantic and Arctic Ocean. The model uses the technique of adaptive grid refinement which allows a high spatial resolution (1 km horizontal, 10 m vertical) around Iceland. The model is used to assess time and space variability of volume and heat fluxes for the years 1997&ndash;2003. Passive tracers are applied to study origin and composition of NIIC water masses. <br><br> The NIIC originates from two sources: the Irminger Current, flowing as part of the sub-polar gyre in 100&ndash;500 m depth along the Reykjanes Ridge and the shallow Icelandic coastal current, flowing north-westward on the south-west Icelandic shelf. The ratio of volume flux between the deep and shallow branch is around 2:1. The NIIC continues as a warm and saline branch northward through Denmark Strait where it entrains large amounts of polar water due to the collision with the southward flowing East Greenland Current. After passing Denmark Strait, the NIIC follows the coast line eastward being an important heat source for north Icelandic waters. <br><br> At least 60% of the temporal temperature variability of north Icelandic waters is caused by the NIIC. The NIIC volume and heat transport is highly variable and depends strongly on the wind field north-east of Denmark Strait. Daily means can change from 1 Sv eastward to 2 Sv westward within a few days. Highest monthly mean transport rates occur in summer when winds from north are weak, whereas the volume flux is reduced by around 50% in winter. Summer heat flux rates can be even three times higher than in winter. The simulation also shows variability on the interannual scale. In particular weak winds from north during winter 2002/2003 combined with mild weather conditions south of Iceland led to anomalous high NIIC volume (+40%) and heat flux (+60%) rates. In this period, simulated north Icelandic water temperatures are at least 0.5 K warmer than average

High resolution modelling of the North Icelandic Irminger Current (NIIC)

International audienceThe northward inflow of Atlantic Water through Denmark Strait ? the North Icelandic Irminger Current (NIIC) ? is simulated with a numerical model of the North Atlantic and Arctic Ocean. The model uses the technique of adaptive grid refinement which allows a high spatial resolution (1 km horizontal, 10 m vertical) around Iceland. The model is used to assess time and space variability of volume and heat fluxes for the years 1997?2003. Passive tracers are applied to study origin and composition of NIIC water masses. The NIIC originates from two sources: the Irminger Current, flowing as part of the sub-polar gyre in 100?500 m depth along the Reykjanes Ridge and the shallow Icelandic coastal current, flowing eastward on the south Icelandic shelf. The ratio between the deep and shallow branch is 0.7/0.2 Sv. The NIIC continues as a warm and saline branch northward through Denmark Strait where it entrains large amounts of polar water due to the collision with the southward flowing East Greenland Current. Tracer model results indicate that north of Denmark Strait at Hornbanki section (at 21°30' W from 66°40' N to 67°30' N), the NIIC is composed of 43% water masses of Atlantic origin (AW) originating from the south and 57% entrained polar or Arctic water masses (PW) coming from the north. After passing Denmark Strait, the NIIC follows the coast line north-eastward where it influences the hydrography of north Icelandic waters. Volume and heat transport is highly variable and depends strongly on the wind field north of Denmark Strait. Highest monthly mean transport rates at Hornbanki occur in summer (0.75 Sv) when northerly winds are weak, lowest transport is observed in winter (0.35 Sv). Summer heat flux rates (14 TW) can be even three times higher than in winter (4 TW). Strong variability can also be observed on the interannual scale. In particular the winter 2002/2003 showed anomalous high transport and heat flux rates. During the period 1997 to 2003 decreasing northerly winds caused an increase of the NIIC volume and heat transport by 30%, leading to a warming of North Icelandic shelf by around 0.5K

Selected bioelements in bark and wood of native tree species from Central-Amazonian inundation forests

The chemical differences between tree foliage from várzea- and igapó forests are confirmed by respective analyses of bark and wood. While generally bark presents higher concentrations than wood, bark and wood of trees from the várzea have higher concentrations than those from the igapó forest. Species composition as well as river water chemistry and soil quality account for the differences between várzea and igapó

Probing the amalgam: the relationship between science teachers’ content, pedagogical and pedagogical content knowledge

This Special Issue aims to present evidence about the relationships between content knowledge (CK), pedagogical knowledge (PK) and pedagogical content knowledge (PCK); the development of these types of knowledge in novice and experienced secondary science teachers; and how CK, PK and/or PCK impact students’ learning. Since Shulman’s introduction of PCK as the feature that distinguishes the teacher from the content expert, researchers have attempted to understand, delineate, assess and/or develop the construct in pre- and in-service teachers. Accordingly, empirical findings are presented that permit further discussion. Outcomes permit post-hoc examination of a recent, collectively described, ‘consensus’ model of PCK, identifying strengths and potential issues. As we will illustrate, the relationship between CK, PK and PCK is central to this; that is, probing the hypothesis of pedagogical content knowledge as an ‘amalgam’ of content and pedagogical knowledge

Foliar nutrient levels of native tree species from Central Amazonia. I. Inundation forests

The study of the leaf size spectra and foliar concentrations of N, P, K, Ca, Mg and Na of 52 species sampled in three Central-Amazon inundation forests (2 várzea sites, 1 igapó site) yielded signifìcant differences between várzea and igapó forests. The várzea foliage consists of larger and less heavy leaves with elemental concentrations being high even by tropical standards. The igapó foliage consists of relatively small leaves which are heavier, but much lower in the studied elements. The igapó leaves are supposed to be sclerophyllous and evergreen

Squeezed Light for the Interferometric Detection of High Frequency Gravitational Waves

The quantum noise of the light field is a fundamental noise source in interferometric gravitational wave detectors. Injected squeezed light is capable of reducing the quantum noise contribution to the detector noise floor to values that surpass the so-called Standard-Quantum-Limit (SQL). In particular, squeezed light is useful for the detection of gravitational waves at high frequencies where interferometers are typically shot-noise limited, although the SQL might not be beaten in this case. We theoretically analyze the quantum noise of the signal-recycled laser interferometric gravitational-wave detector GEO600 with additional input and output optics, namely frequency-dependent squeezing of the vacuum state of light entering the dark port and frequency-dependent homodyne detection. We focus on the frequency range between 1 kHz and 10 kHz, where, although signal recycled, the detector is still shot-noise limited. It is found that the GEO600 detector with present design parameters will benefit from frequency dependent squeezed light. Assuming a squeezing strength of -6 dB in quantum noise variance, the interferometer will become thermal noise limited up to 4 kHz without further reduction of bandwidth. At higher frequencies the linear noise spectral density of GEO600 will still be dominated by shot-noise and improved by a factor of 10^{6dB/20dB}~2 according to the squeezing strength assumed. The interferometer might reach a strain sensitivity of 6x10^{-23} above 1 kHz (tunable) with a bandwidth of around 350 Hz. We propose a scheme to implement the desired frequency dependent squeezing by introducing an additional optical component to GEO600s signal-recycling cavity.Comment: Presentation at AMALDI Conference 2003 in Pis