Exploring biological constraints on the glacial history of Antarctica

The evolutionary and biogeographic history of the contemporary Antarctic terrestrial and marine biotas reveals many components of ancient origin. For large elements of the terrestrial biota, long-term isolation over timescales from hundreds of thousands to tens of millions of years, and thus persistence through multiple glacial cycles, now appears to be the norm rather than the exception. For the marine biota there are some parallels with benthic communities also including ancient components, together with an incidence of species-level endemism indicating long-term isolation on the Antarctic continental shelf. Although it has long been known that a few ice-free terrestrial locations have existed in Antarctica for up to 10–12 million years, particularly in the Dry Valleys of Victoria Land along with certain nunataks and higher regions of large mountain ranges, these do not provide potential refugia for the majority of terrestrial biota, which occur mainly in coastal and/or low-lying locations and exhibit considerable biogeographic regionalisation within the continent. Current glacial models and reconstructions do not have the spatial resolution to detect unequivocally either the number or geographical distribution of these glacial refugia, or areas of the continental shelf that have remained periodically free from ice scouring, but do provide limits for their maximum spatial extent. Recent work on the evolution of the terrestrial biota indicates that refugia were much more widespread than has been recognised and it is now clear that terrestrial biology provides novel constraints for reconstructing the past glacial history of Antarctica, and new marine biological investigations of the Antarctic shelf are starting to do likewise.     

Chronology of Late Weichselian glaciation in the western part of the East European Plain

A database consisting of radiocarbon (¹⁴C), optically stimulated luminescence (OSL), thermoluminescence (TL) and beryllium (¹⁰Be) dates was used for timing the advance of the Late Weichselian Scandinavian Ice Sheet (SIS), determining the age of the Last Glacial Maximum (LGM) and the rate of deglaciation. The study area encompasses the southeastern sector of the last SIS between the Baltic Sea and the LGM position in the western part of the East European Plain, covering the Karelian Ice‐Stream Complex (ISC) area in the east and the Baltic ISC area in the west. The linear advance and recession rates of the last SIS were estimated to be between 110 and 330 m a^?1 and between 50 and 170 m a^?1, respectively. The onset of the last SIS in the Karelian ISC area reached the western shores of Latvia not before 26 OSL ka, and in the Baltic ISC area, on the southern shores of the Gulf of Finland, not before 21 OSL ka. The last SIS reached close to the LGM position earliest in NW Belarus, not earlier than 22.6 cal. ¹⁴C ka BP, and latest in the NE of Belarus, not earlier than 19.1 cal. ¹⁴C ka BP. The Baltic ISC area between the LGM position and the western shores of Latvia was deglaciated in about 8 ka, and in the Karelian ISC area, between the LGM position and the southern shores of the Gulf of Finland, in about 2.6 ka. The whole area between the LGM position and the Baltic Sea was deglaciated between 14.2 ¹⁰Be ka and 13.3 cal. ¹⁴C ka BP.     

On the quasi-periodic oscillations in magnetars

We study torsional Alfvén oscillations of magnetars, that is neutron stars with a strong magnetic field. We consider the poloidal and toroidal components of the magnetic field and a wide range of equilibrium stellar models. We use a new coordinate system  ( X , Y )  , where     and     and a ₁ is the radial component of the magnetic field. In this coordinate system, the one+two-dimensional evolution equation describing the quasi-periodic oscillations (QPOs), see Sotani et al., is reduced to a one+one-dimensional equation where the perturbations propagate only along the y -axis. We solve the one+one-dimensional equation for different boundary conditions and the open magnetic field lines, that is magnetic field lines that reach the surface and there match up with the exterior dipole magnetic field as well as closed magnetic lines, i.e. magnetic lines that never reach the stellar surface. For the open field lines, we find two families of QPO frequencies: a family of 'lower' QPO frequencies which is located near the x -axis and a family of 'upper' frequencies located near the y -axis. According to Levin, the fundamental frequencies of these two families can be interpreted as the turning point of the continuous spectrum. We find that the upper frequencies are multiples of the lower ones by a constant equalling  2 n + 1  . For the closed lines, the corresponding factor is   n + 1  . By using these relations, we can explain both the lower and the higher observed frequencies in SGR 1806−20 and SGR 1900+14.     

Hedonic Pricing of Climate Change Impacts to Households in Great Britain

This study investigates the amenity value of climate to British households. By using the hedonic price approach, the marginal willingness to pay for small changes in climate variables is derived. Various indices of temperature and precipitation are used including means, ranges, extremes and January and July averages. We specify one hedonic regression including information on house prices and wage data for 755 Posttowns and found the model containing January and July averages of temperature and precipitation most appropriate. The estimates suggest that British people would typically prefer higher temperatures in January. Increased precipitation in January is likely to reduce welfare. Changes in temperature and precipitation in July are not significant. Limited global warming, with a more pronounced effect of temperature increases compared to higher precipitation levels during winter months, might thus benefit British households.     

Quaternary tephrachronology on the Iceland Plateau,north of Iceland

Four major ash zones recorded in piston cores raised from the Iceland Plateau north of Iceland are shown to be coincident with the last four interglacial isotopic stages. Their geochemical composition links the ashes to volcanic events on Iceland. The occurrence of these ash layers, which record events orders of magnitude larger than the ‘normal’ Holocene volcanic eruptions, can not be explained by changes in sea ice cover and atmospheric circulation alone. It is suggested that these events are related to pressure releases in the magma chambers resulting from major deglaciations of the Icelandic Ice Cap.     

Integralgeometrische Bestimmung geotechnisch wichtiger Klufteigenschaften

ZusammenfassungIntegralgeometrische Bestimmung geotechnisch wichtiger Klufteigenschaften Einfache Formeln werden dargelegt, nach denen geotechnisch wichtige Klufteigenschaften berechnet werden können, z. B. die Länge des Kluftanschnittlinears, die Kluftfläche, die Kluftöffnung, das Kluftvolumen und die Kantenlänge der Kluftkörper. Dazu werden deren integralgeometrische Herleitungen angegeben, um mit publizierten Ausdrücken für derartige Klufteigenschaften vergleichen zu können.Meßverfahren werden erläutert, die zum Erfassen der Merkmale dienen, aus denen die Klufteigenschaften berechnet werden können: leicht bestimmbare Punktanzahlen und Längen entlang von Meßgeraden sowie Punktanzahlen auf Meßflächen.An einem Verwitterungsprofil eines oberdevonischen Siltsteines wird getestet, wie aussagekräftig die integralgeometrisch abgeleiteten Formeln sind.

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SummaryOn the Determination of Some Important Geotechnical Joint Properties by Means of Integral Geometry Simple equations are presented which are useful to evaluate properties of joints important in rock mechanics, e. g. the length of linear of intersected joints, the joint area, the joint opening, the joint volume, and the edge length of rock blocks defined by joints. Also, the integral-geometrical derivation of the equations is presented to compare these with previously published expressions for such joint properties.Methods of measurement are illustrated to record the features from which the joint properties are evaluated: simply determinable numbers of points and lengths along measuring lines and numbers of points on measuring areas.The potential usefulness of the integral-geometrically derived equations is tested on a weathering profile of a Upper Devonian siltstone.

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RésuméDétermination par la géométrie intégrale des caractéristiques géotechniques des failles On propose des formules simples à partir desquelles on peut calculer les caractéristiques des failles intéressantes au point de vue géotechnique, par exemple la longueur des lignes de failles coupées, le plan de faille, l'ouverture de la faille, le volume des failles et la longueur des bords des polyèdres délimités par les plans de failles. En plus, les formules sont déduites à l'aide de la géométrie intégrale pour qu'on puisse les comparer à des formules décrivant les caractéristiques des failles qu'on a déjà publiées.On explique des méthodes de mesure qui servent à enregistrer les signes particuliers au moyen desquels on peut calculer les caractéristiques des failles: des nombres de points et des longueurs mesurés le long des lignes de mesure ainsi que des nombres de points sur des plans de mesure.Pour montrer l'utilité des formules déduites à l'aide de la géométrie intégrale on donne un exemple: un profil de désagrégation dans le schiste argileux du Dévonien supérieur.

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Mit 10 Abbildungen     

Modellierung der Zwickauer Mulde - Beschreibungsmodelle

Für die Fließstrecke der Zwickauer Mulde zwischen den Pegeln Zwickau-Pölbitz und Göhren werden statische und dynamische Beschreibungsmodelle angegeben, die anhand kontinuierlich gewonnener Meßwerte von Einflußgrößen der Wasserbeschaffenheit mit einem Diskretisierungsabstand von Δt = 2 h gebildet wurden. Neben den statistischen Auswertungen werden rekursiv geschätzte Sauerstoffmodelle für den Pegel Göhren und für die gesamte Fließstrecke dargestellt.     

Compound summer temperature and precipitation extremes over central Europe

Theoretical and Applied Climatology - Reliable knowledge of the near-future climate change signal of extremes is important for adaptation and mitigation strategies. Especially compound extremes,...