A microscopic modeling of phonon dynamics and charge response in metallic BaBiO3_3

We use our recently proposed microscopic modeling in the framework of linear response theory to investigate the complete phonon dispersion, the phonon density of states, certain phonon-induced electronic charge distributions and charge fluctuations (CF's) for anomalous soft modes of metallic BaBiO$_{3}$ in its simple cubic phase where superconductivity with $T_{c}$ up to 32 K appears. The theoretical approach already has been applied successfully to the cuprate high-temperature superconductors (HTSC's), simple ionic crystals (NaCl, MgO) and perovskite oxides (SrTiO$_{3}$, BaTiO$_{3}$). It is well suited for materials with a strong component of ionic binding and especially for "ionic" metals. In particular, the giant phonon anomalies related to the breathing vibration of the oxygen as found experimentally in superconducting doped Ba$_{0.6}$K$_{0.4}$BiO$_{3}$, resembling those observed in the high $T_{c}$ cuprates, are investigated. The origin of these anomalies is explored and attributed to a strong nonlocal coupling of the displaced oxygen ions to CF's of ionic type, essentially of the Bi6s- and Bi6p orbital. This points to the importance of both of these states at the Fermi energy. Starting from an ab-initio rigid ion model (RIM) we calculate the effect on the lattice dynamics and charge response of the most important electronic polarization processes in the material, i.e. CF's and dipole fluctuations (DF's). Taking into account these electronic degrees of freedom in linear response theory, we obtain a good agreement with the measured phonon dispersion and in particular with the strong phonon anomalies.Comment: Additional comparison with the cuprate HTSC's. A slightly shorter version has been published in PR

Fast analytical two-stream radiative transfer methods for horizontally homogeneous vegetation media

This work reports on the two-stream radiative transfer in a horizontally homogeneous turbid vegetation medium assuming bi-Lambertian leaf scattering by planar model leaves. The deduced two-stream radiative transport equations are solved analytically for various leaf architectures considering leaf normal distribution (LND) functions from purely vertical to purely horizontal leaves. These transfer models are driven by radiative energy flux densities (EFDs) incident at the top of the vegetation (TOV) and separated into their diffuse and direct fractions, used as upper boundary conditions. The radiance field is treated as approximately isotropic, but its zenithal distribution can be varied by the so-called diffusivity factor, which allows together with the incident EFDs at TOV to take the sky conditions above the canopy into account. Simulations of the canopy reflectance and transmittance are performed in the UV/VIS as function of the solar zenith angle and the ratio of the direct and diffuse sky light above the canopy representing clear and overcast sky conditions. These computations demonstrate that the radiative transfer in vegetation is significantly influenced by this ratio and the LND of the leaves.Diese Arbeit berichtet ¨uber den Zweistrom-Strahlungstransfer eines horizontal homogenen und trüben Vegetationsmediums, wobei bi-Lambertsche Streuung an als eben betrachteten Modellblätter angenommen wird. Die abgeleiteten Zweistrom-Strahlungstransportgleichungen werden analytisch gelöst für verschiedene Blattarchitekturen, indem Blattnormalenverteilungsfunktionen (BNV) von rein vertikalen bis rein horizontale Bl¨atter ber¨ucksichtigt werden. Diese Transfermodelle werden durch Strahlungsflussdichten angetrieben, die am Oberrand der Vegetation gegeben und in deren Direkt- und Diffusanteil aufgespalten sind, wobei letztere als obere Randbedingungen fungieren. Das Strahldichtefeld wird als nahezu isotrop angenommen, jedoch kann dessen Zenitwinkelabh¨angigkeit durch den sogenannten Diffusivit¨atsfaktor variiert werden, der es zusammen mit den am Oberrand einfallenden Strahlungsflussdichten erlaubt, unterschiedliche Bedingungen f¨ur das atmosph ¨arische Himmelslicht zu ber¨ucksichtigen. Es wurden Simulationen der Reflektanz und Transmittanz des Gesamtmediums im UV/VIS als Funktion des Sonnenzenitwinkels sowie des Verh¨altnisses des Direkt- und Diffuslichts durchgef¨uhrt, stellvertretend f¨ur klare Tage und bew¨olkte Situationen. Diese Berechnungen zeigen, dass der Strahlungstransfer in Vegetation deutlich von diesem Verh¨altnis sowie von der BNV der Bl¨atter abh¨angt

Niederschlagsderivate

Some traders estimate precipitation derivatives to have a potential which increases even that of temperature derivatives. Precipitation derivatives can be used both for hedging and marketing purposes for a diverse number of possible end users. However, the complex way of measuring precipitation, the lack of qualitative data and the feature of precipitation as being locally and timely variable make it necessary to develop highly individual contracts to keep the basis risk low. --Precipitation derivatives,weather derivatives,weather risk management,hedging,base risk,liquidity,precipitation variability

Simulations of solar radiative transfer in measured and generated cloud fields

Um ein besseres Verständnis des Einflusses von Wolken auf den Strahlungstransport zu erlangen, müssen neben direkten Messungen der Strahlungsgrößen auch Strahlungstransportrechnungen durchgeführt werden. Dabei werden mikrophysikalische Eigenschaften aus Fernerkundungs- und in situ Messungen sowie generierte Wolkenfelder verwendet. In den BBC1- und BBC2 (= Baltex Bridge Cloud 1 und 2)-Messkampagnen wurden Messungen der mikrophysikalischen Wolkeneigenschaften und der Strahlungsgrößen durchgeführt. In diesem Bericht werden Ergebnisse von spektralen Monte Carlo Simulationen des Strahlungstransports in der Kurzwellenregion für Wellenlängen zwischen 350 nm und 850 nm für einen in BBC1 gemessenen Stratocumulus gezeigt. Zusätzlich wurden auch Strahlungstransportssimulationen für einen LES (= Large Eddy Simulation)- simulierten Cumulus und für eine entsprechende IAAFT (= Iterative Amplitude Adapted Fourier Transform)-Surrogatwolke mit denselben statistischen Eigenschaften wie die ursprüngliche Wolke durchgeführt.For a better understanding of the role that clouds play in the radiative transfer (RT) across the atmosphere, computer RT simulations with microphysical data retrieved from remote sensing and in situ measurements as well as with cloud fields provided by cloud generators have to be carried out in addition to field measurements campaigns. In this work we show spectral RT results for two cloud studies. During the BBC1 and BBC2 (=Baltex Bridge Cloud 1 and 2) campaigns measurements of cloud radiation and microphysics properties have been performed. We present here the results of a series of quasi-spectral simulations covering the shortwave region (from 350 nm up to 850 nm) for a remote-sensing captured stratocumulus. RT calculations have also been carried out for a LES (=Large Eddy Simulation) cumulus and an IAAFT (=Iterative Amplitude Adapted Fourier Transform) surrogate cloud with the same statistics as the original

Comment: Which Old Witch: A Comment on Professor Paulsen\u27s \u3ci\u3eLemon is Dead\u3c/i\u3e

International audienc

Hydrogen Peroxide Versus Sodium Hypochlorite: All a Matter of pH?

Introduction: Hydrogen peroxide (H2O2) and sodium hypochlorite (NaOCl) solutions are similar in that they contain oxidizing agents with a bleaching effect. NaOCl solutions are stable at a high pH, at which they also exert increased cleansing/proteolysis. On the other hand, H2O2 solutions are natively acidic, yet gain bleaching power on organic stains when alkalized. It was investigated whether alkalizing a H2O2 solution would also let it dissolve soft tissue or increase its bleaching power on blood-stained dentin. Methods: The stability of alkalized H2O2 solutions was assessed by iodometric titration. Soft tissue dissolution was investigated on porcine palatal mucosa. The bleaching effect (ΔL∗) after 60 minutes of exposure was monitored in blood-stained human dentin using a calibrated spectrophotometer. To compare similar molarities, 2.5% H2O2 solutions were used here, and 5.0% NaOCl was used as the positive control, whereas nonbuffered saline solution served as the negative control. Results: Adding alkali (NaOH) to the H2O2 solutions rendered them unstable in a dose-dependent manner. A H2O2 solution of pH 11.1 was chosen for the main experiments (tissue dissolution and bleaching effect) and compared with a native counterpart (pH = 4.7). Alkalizing the H2O2 solution had no discernible effect on its soft tissue dissolution or bleaching power (P = .75 compared with the native H2O2 solution). The NaOCl solution of similar molar concentration had a considerably (P < .001) higher tissue dissolving and bleaching effect under current conditions. Conclusions: The proteolytic/bleaching effects of NaOCl solutions are unique and cannot be achieved by altering the pH of peroxide solutions. Keywords: Bleaching; dentin; hydrogen peroxide; tissue dissolution

India and the Study of Kinship Terminologies

L’Inde et l’étude des terminologies de parenté. – L’étude des terminologies de parenté s’est développée au xviiie siècle à partir de l’ethnologie linguistique, laquelle souhaitait découvrir les relations historiques existant entre les nations en étudiant celles entre les langues en se servant de listes de mots du vocabulaire courant comprenant des termes de parenté. Lewis H. Morgan fut le premier à conceptualiser la terminologie de parenté en tant qu’ensemble intégré. L’Inde et la terminologie dravidienne ont joué un rôle important dans l’histoire des études de la parenté. La plupart des avancées actuelles concernant l’étude de la terminologie de parenté sont dues au structuralisme, bien que l’apport de l’évolutionnisme ne soit pas encore dépassé et que celui de l’historicisme reste encore à venir.The study of kinship terminologies grew out of the eighteenth-century project of linguistic ethnology, which sought to uncover the historical relations among nations by determining the relations among languages, using lists of core vocabulary items including kinship terms. Lewis H. Morgan was the first to conceptualize the kinship terminology as an integrated set. India and the Dravidian kinship terminology have played a large role in the history of kinship study. Most modern advances in the study of kinship terminology are owed to structuralism, though the contributions of evolutionism are not entirely in the past, and those of historicism lie largely in the future

Assessment of a Physics-based Retrieval of Exoplanet Atmospheric Temperatures from Infrared Emission Spectra

Atmospheric temperatures are to be estimated from thermal emission spectra of Earth-like exoplanets orbiting M-stars as observed by current and future planned missions. To this end, a line-by-line radiative transfer code is used to generate synthetic thermal infrared (TIR) observations. The range of 'observed' intensities provides a rough hint of the atmospheric temperature range without any a priori knowledge. The equivalent brightness temperature (related to intensities by Planck's function) at certain wavenumbers can be used to estimate the atmospheric temperature at corresponding altitudes. To exploit the full information provided by the measurement we generalize Chahine's original approach and infer atmospheric temperatures from all spectral data using the wavenumber-to-altitude mapping defined by the weighting functions. Chahine relaxation allows an iterative refinement of this 'first guess'. Analysis of the 4.3{\mu}m and 15{\mu}m carbon dioxide TIR bands enables an estimate of atmospheric temperatures for rocky exoplanets even for low signal to noise ratios of 10 and medium resolution. Inference of Trappist-1e temperatures is, however, more challenging especially for CO2 dominated atmospheres: the 'standard' 4.3{\mu}m and 15{\mu}m regions are optically thick and an extension of the spectral range towards atmospheric window regions is important. If atmospheric composition (essentially CO2 concentration) is known temperatures can be estimated remarkably well, quality measures such as the residual norm provide hints on incorrect abundances. In conclusion, temperature in the mid atmosphere of Earth-like planets orbiting cooler stars can be quickly estimated from thermal IR emission spectra with moderate resolution.Comment: 16 pages, 19 figures, 1 tabl

Spectral features of Earth-like planets and their detectability at different orbital distances around F, G, and K-type stars

We investigate the spectral appearance of Earth-like exoplanets in the HZ of different main sequence stars at different orbital distances. We furthermore discuss for which of these scenarios biomarker absorption bands may be detected during primary or secondary transit with near-future telescopes and instruments.We analyze the spectra taking into account different filter bandpasses of two photometric instruments planned to be mounted to the JWST. We analyze in which filters and for which scenarios molecular absorption bands are detectable when using the space-borne JWST or the ground-based telescope E-ELT. Absorption bands of CO2, H2O, CH4 and O3 are clearly visible in high-resolution spectra as well as in the filters of photometric instruments. However, only during primary eclipse bands of CO2, H2O and O3 are detectable for all scenarios when using photometric instruments and an E-ELT telescope setup. CH4 is only detectable at the outer HZ of the K star since here the atmospheric modeling results in very high abundances. Since the detectable CO2 and H2O bands overlap, separate bands need to be observed to prove their existence in the atmosphere. In order to detect H2O in a separate band, a S/N>7 needs to be achieved for E-ELT observations, e.g. by co-adding at least 10 transit observations. Using a spaceborne telescope like the JWST enables the detection of CO2 at 4.3mu, which is not possible for ground-based observations due to the Earth's atmospheric absorption. Hence combining observations of spaceborne and groundbased telescopes might allow to detect the presence of the biomarker molecule O3 and the related compounds H2O and CO2 in a planetary atmosphere. Other absorption bands using the JWST can only be detected for much higher S/Ns, which is not achievable by just co-adding transit observations since this would be far beyond the planned mission time of JWST.(abridged)Comment: 15 pages, 8 figure