Postglacial, relative shore-level changes in Lillebælt, Denmark

The brackish Baltic Sea and the more saline Kattegat are connected by three straits, Lillebælt, Storebælt and Øresund (Fig. 1). Of the three straits, Lillebælt is the narrowest, with 700 m at its narrowest point, widening out towards the south to around 25 km (Fig. 2). In the narrow parts of Lillebælt, water depths around 30–50 m are common. In the northern part of Lillebælt the depth is 16–18 m and in the southern part the depth is around 35 m. Storebælt and Øresund have played important roles as outlets during the history of the Baltic Sea, and their histories have been much discussed (Björck 1995; Bennike et al. 2004). In contrast, Lillebælt has received little attention. In this paper we present 11 new radiocarbon accelerator mass spectrometry (AMS) ages and propose a curve for Holocene relative shore-level changes in Lillebælt. We use the term shore-level changes rather than sea-level changes because we have constructed both lake-level and sea-level changes

Avant-propos

Résumé  37-2,167-86 Jørn Boisen: L'objectif de la présente étude est d'isoler un problème fondamental de l'esthétique et de la pensée de Kundera, à savoir comment explorer des thèmes philosophiques par des moyens romanesques ? Le soupçon du roman à thèse plane sur chaque roman qui contient une forte présence du penser. Pour réfuter cette accusation, le texte tente de dégager la relation très spécifique entre certaines propositions nietzschéennes, explicitement présentées et discutées dans L'insoutenable légèreté de l'être, et le destin d'un des personnages, la serveuse Térésa. L'analyse montre que le roman pensé de Kundera ne devient ni une défense ni une illustration des thèses philosophiques préétablies mais, au contraire, une exploration ambiguë et paradoxale de ce que deviennent les thèmes philosophiques dans « le monde de la vie »

Current-induced noise and damping in non-uniform ferromagnets

In the presence of spatial variation of the magnetization direction, electric current noise causes a fluctuating spin-transfer torque that increases the fluctuations of the ferromagnetic order parameter. By the fluctuation-dissipation theorem, the equilibrium fluctuations are related to the magnetization damping, which in non-uniform ferromagnets acquires a nonlocal tensor structure. In biased ferromagnets, shot noise can become the dominant contribution to the magnetization noise at low temperatures. Considering spin spirals as a simple example, we show that the current-induced noise and damping is significant.Comment: 5 pages, 1 figur

Optical properties of InAlGaAs quantum wells: Influence of segregation and band bowing

Knowledge of the quaternary InAlGaAs material system is very limited for the composition range relevant for growth on GaAs substrates. We report on the characterization and modeling of InAlGaAs quantum wells with AlGaAs barriers, grown pseudomorphically on a GaAs substrate with molecular beam epitaxy. The quantum wells are characterized with photoluminescence, and the measured transition energies are modeled taking into account the influence of In segregation on the shape of the well potential. From the modeling we deduce a relation for the low temperature band gap of unstrained Inx(AlyGa1−y)1−xAs, for 0⩽x,y⩽0.20. The measured linewidths of the luminescence peaks are in agreement with the broadening expected from random alloy fluctuations and well width fluctuations with an effective interface roughness of 1.1 ML

The vascular conducted response in cerebral blood flow regulation

Despite recent advances in our understanding of the molecular and cellular mechanisms behind vascular conducted responses (VCRs) in systemic arterioles, we still know very little about their potential physiological and pathophysiological role in brain penetrating arterioles controlling blood flow to the deeper areas of the brain. The scope of the present review is to present an overview of the conceptual, mechanistic, and physiological role of VCRs in resistance vessels, and to discuss in detail the recent advances in our knowledge of VCRs in brain arterioles controlling cerebral blood flow. We provide a schematic view of the ion channels and intercellular communication pathways necessary for conduction of an electrical and mechanical response in the arteriolar wall, and discuss the local signaling mechanisms and cellular pathway involved in the responses to different local stimuli and in different vascular beds. Physiological modulation of VCRs, which is a rather new finding in this field, is discussed in the light of changes in plasma membrane ion channel conductance as a function of health status or disease. Finally, we discuss the possible role of VCRs in cerebrovascular function and disease as well as suggest future directions for studying VCRs in the cerebral circulation

The Storebælt gateway to the Baltic

The present-day Storebælt (Great Belt), the waterway between the islands of Fyn and Sjælland (Fig. 1), contains deeply incised valleys, locally more than 50 m deep, and is of crucial importance to the water exchange between the fully marine Kattegat and the brackish Baltic Sea. The role of this important gateway changed significantly during the late and post-glacial period (since 15000 B.P.), when the Baltic Basin experienced alternating freshwater, brackish and marine conditions as a result of changes in relative sea level (Figs 2, 3). The importance of the Storebælt in understanding the dynamics of the Baltic Basin is reflected in the large number of studies carried out (see Bennike et al. 2004). The first detailed sedimentological and stratigraphic studies in the Storebælt area that demonstrated the presence of early Holocene freshwater deposits below the seabed were those of Krog (1960, 1965, 1971), who also presented the first shore-displacement curve for the area (Krog 1979)

Ultranarrow polaritons in a semiconductor microcavity

We have achieved a record high ratio (19) of the Rabi splitting (3.6 meV) to the polaritonlinewidth (190 μeV), in a semiconductor λ microcavity with a single 25 nm GaAsquantum well at the antinode. The narrow polariton lines are obtained with a special cavity design which reduces the exciton broadening due to scattering with free charges and has a very low spatial gradient of the cavity resonance energy. Since the static quantum-well disorder is very small, the polariton broadening is dominantly homogeneous. Still, the measured linewidths close to zero detuning cannot be correctly predicted using the linewidth averaging model