Comparisons of global topographic/isostatic models to the Earth's observed gravity field

The Earth's gravitational potential, as described by a spherical harmonic expansion to degree 180, was compared to the potential implied by the topography and its isostatic compensation using five different hypothesis. Initially, series expressions for the Airy/Heiskanen topographic isostatic model were developed to the third order in terms of (h/R), where h is equivalent rock topography and R is a mean Earth radius. Using actual topographic developments for the Earth, it was found that the second and third terms of the expansion contributed 30 and 3 percents, of the first of the expansion. With these new equations it is possible to compute depths (D) of compensation, by degree, using 3 different criteria. The results show that the average depth implied by criterion I is 60 km while it is about 33 km for criteria 2 and 3 with smaller compensation depths at the higher degrees. Another model examined was related to the Vening-Meinesz regional hypothesis implemented in the spectral domain. Finally, oceanic and continental response functions were derived for the global data sets and comparisons made to locally determined values

Strategies for Financing Large-scale Carbon Capture and Storage Power Plants in China

Building on previous stakeholder consultations from 2006 to 2010, we conduct a financial analysis for a generic CCS power plant in China. In comparison with conventional thermal generation technologies, a coal-fired power plant with CCS requires either a 70% higher on-grid electricity tariff or carbon price support of approximately US$50/tonne CO2 in the absence of any other incentive mechanisms or financing strategies. Given the difficulties of relying on any one single measure to finance a large-scale CCS power plant in China, we explore a combination of possible financing mechanisms. Potential measures available for increasing the return on the CCS investment include: enhanced oil recovery (EOR), a premium electricity tariff, and operational investment flexibility (e.g. solvent storage, upgradability). A simulation found that combining several financing options could not only provide private investors with a 12% to 18% return on equity (ROE), but also significantly reduce the required on-grid tariff to a level that is very close to the tariff level of existing coal-fired power plants and much lower than the tariffs for natural gas combined cycle and nuclear power plants. Therefore, we suggest that a combination of existing financing measures could trigger private investment in a large-scale CCS power plant in China

Quaternary quadratic lattices over number fields

We relate proper isometry classes of maximal lattices in a totally definite quaternary quadratic space (V,q) with trivial discriminant to certain equivalence classes of ideals in the quaternion algebra representing the Clifford invariant of (V,q). This yields a good algorithm to enumerate a system of representatives of proper isometry classes of lattices in genera of maximal lattices in (V,q)

Quality of Heusler Single Crystals Examined by Depth Dependent Positron Annihilation Techniques

Heusler compounds exhibit a wide range of different electronic ground states and are hence expected to be applicable as functional materials in novel electronic and spintronic devices. Since the growth of large and defect-free Heusler crystals is still challenging, single crystals of Fe2TiSn and Cu2MnAl were grown by the optical floating zone technique. Two positron annihilation techniques -Angular Correlation of Annihilation Radiation (ACAR) and Doppler Broadening Spectroscopy (DBS)- were applied in order to study both, the electronic structure and lattice defects. Recently, we succeeded to observe clearly the anisotropy of the Fermi surface of Cu2MnAl, whereas the spectra of Fe2TiSn were disturbed by foreign phases. In order to estimate the defect concentration in different samples of Heusler compounds the positron diffusion length was determined by DBS using a monoenergetic positron beam

Towards a unification of HRT and SCOZA. Analysis of exactly solvable mean-spherical and generalized mean-spherical models

The hierarchical reference theory (HRT) and the self-consistent Ornstein-Zernike approximation (SCOZA) are two liquid state theories that both furnish a largely satisfactory description of the critical region as well as the phase coexistence and equation of state in general. Furthermore, there are a number of similarities that suggest the possibility of a unification of both theories. Earlier in this respect we have studied consistency between the internal energy and free energy routes. As a next step toward this goal we here consider consistency with the compressibility route too, but we restrict explicit evaluations to a model whose exact solution is known showing that a unification works in that case. The model in question is the mean spherical model (MSM) which we here extend to a generalized MSM (GMSM). For this case, we show that the correct solutions can be recovered from suitable boundary conditions through either of SCOZA or HRT alone as well as by the combined theory. Furthermore, the relation between the HRT-SCOZA equations and those of SCOZA and HRT becomes transparent.Comment: Minimal correction of some typos found during proof reading. Accepted for publication in Phys. Rev.

Die Bildungsbeteiligung deutscher und ausländischer Jugendlicher in der Bundesrepublik Deutschland

"Der Beitrag untersucht mit den Daten des Mikrozensus 1995 die Determinanten der Beteiligung deutscher und nicht-deutscher Jugendlicher an den Jahrgangsstufen 1113 der Gymnasien. Dabei werden bei den Jugendlichen ohne deutsche Staatsangehörigkeit die numerisch größten Herkunftsgruppen (Türkei, ehemaliges Jugoslawien, EU und andere) unterschieden. Die wichtigsten Determinanten sind die Bildungsabschlüsse der Eltern, der Generationenabstand und das Haushaltsnettoeinkommen. Nach Kontrolle aller individueller Faktoren besitzt die Nationalität nach wie vor einen signifikanten Einfluß: Während Jugendliche aus EU-Staaten oder der Gruppe der anderen Länder keine unterschiedliche Beteiligung gegenüber deutschen Jugendlichen aufweisen, ist die Wahrscheinlichkeit eines Besuchs der Gymnasial-Oberstufe bei Jugendlichen aus dem ehemaligen Jugoslawien am niedrigsten und auch bei türkischen Jugendlichen signifikant reduziert. Unter den ausländischen Jugendlichen ist der Bildungsabschluß der Haushaltsbezugsperson eine noch wichtigere Determinante als bei deutschen Jugendlichen. Die Anteile der Erwachsenen mit erfolgreichem Bildungsabschluß steigen allerdings bei allen Nationalitäten deutlich. Jüngere Erwachsene haben (außer bei Deutschen) im Durchschnitt zu einem wesentlich höheren Anteil einen Schulabschluß als Ältere." (Autorenreferat)"Employing the German microcensus of 1995 determinants of the attendance of high school classes 11-13 are examined for German and non-German teenagers. Non-Germans are subdivided into the largest nationality groups (Turkey, former Yugoslavia, EU-countries and all other nationalities). The most important determinants are parental education, the age difference between parents and child, and the household income. After controlling for all individual variables nationality still has a significant influence: whereas teenagers from EU-countries and of all other nationalities show no difference to Germans the probability of school attendance in classes 11-13 is smallest for teenagers from former Yugoslavia, and is also significant reduced for Turkish nationals. For non-German teenagers parental education is even more important than for the Germans. The share of adults with at least one finished educational degree is rising for all nationalities. Except of Germans in average the share of persons with at least one finished educational degree is higher for younger than for older adults." (author's abstract

Statistically measuring the amount of pitch angle scattering that energetic electrons undergo as they drift across the plasmaspheric drainage plume at geosynchronous orbit

Using five spacecraft in geosynchronous orbit, plasmaspheric drainage plumes are located in the dayside magnetosphere and the measured pitch angle anisotropies of radiation belt electrons are compared duskward and dawnward of the plumes. Two hundred twenty‐six plume crossings are analyzed. It is found that the radiation belt anisotropy is systematically greater dawnward of plumes (before the electrons cross the plumes) than it is duskward of plumes (after the electrons have crossed the plumes). This change in anisotropy is attributed to pitch angle scattering of the radiation belt electrons during their passage through the plumes. A test database in the absence of plumes finds no equivalent change in the radiation belt anisotropy. The amount of pitch angle scattering by the plume is quantified, scattering times are estimated, and effective pitch angle diffusion coefficients within the plume are estimated. The pitch angle diffusion coefficients obtained from the scattering measurements are of the same magnitude as expected values for electromagnetic ion cyclotron (EMIC) waves at high electron energies (1.5 MeV); however, expected EMIC diffusion coefficients do not extend to pitch angles of 90° and would have difficulties explaining the observed isotropization of electrons. The pitch angle diffusion coefficients obtained from the scattering measurements are of the same magnitude as expected values for whistler mode hiss at lower electron energies (150 keV). Outward radial transport of the radiation belt caused by the pitch angle scattering in the plume is discussed. Key Points Radiation belt pitch angle scattering within the drainage plume is strong The amount of scattering agrees with diffusion coefficients in the literature The pitch angle scattering leads to radial transport of the radiation beltPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106858/1/jgra50883.pd

Conditional control of quantum beats in a cavity QED system

We probe a ground-state superposition that produces a quantum beat in the intensity correlation of a two-mode cavity QED system. We mix drive with scattered light from an atomic beam traversing the cavity, and effectively measure the interference between the drive and the light from the atom. When a photon escapes the cavity, and upon detection, it triggers our feedback which modulates the drive at the same beat frequency but opposite phase for a given time window. This results in a partial interruption of the beat oscillation in the correlation function, that then returns to oscillate.Comment: 9 pages, 5 figures, XVII Reuni\'on Iberoamericana de \'Optica, X Encuentro de \'Optica, L\'aseres y Aplicaciones (RIAO-OPTILAS-2010