Wachstum und Konjunktur in OECD-Ländern: Eine langfristige Perspektive

Gemessen an der Wachstumsrate des realen Bruttoinlandsprodukts weist Deutschland im internationalen Vergleich in den letzten Jahren eine besonders schlechte Wirtschaftsleistung auf. Ob dies eher eine ungünstige konjunkturelle Entwicklung widerspiegelt oder ob sich dahinter eine langfristige Wachstumsschwäche verbirgt, wird hier mit Hilfe eines Strukturellen Zeitreihenmodells ermittelt. Das Modell stellt für verschiedene OECD-Länder von 1950 bis 2004 die Beiträge von Konjunktur und langfristigem Trend zu den Wachstumsraten des BIP dar. Die Ergebnisse zeigen, dass die Trendwachstumsrate seit den fünfziger Jahren in allen analysierten Ländern zurückging. Besonders stark war aber der Rückgang in Deutschland. Das heißt, dass die enttäuschende wirtschaftliche Entwicklung in Deutschland vor allem auf die niedrige langfristige Trendwachstumsrate zurückzuführen ist und deutet auf bereits seit langem bestehende Strukturprobleme in Deutschland hin.Wirtschaftswachstum, Konjunktur, Prognose, Wirtschaftspolitik, Deutschland, OECD-Staaten

ifo Konjunkturprognose 2006/2007: Aufschwung setzt sich fort

Die Weltwirtschaft ist in einem robusten Aufschwung. Das vom ifo Institut erhobene Weltwirtschaftsklima hat sich im Frühjahr 2006 zum dritten Mal in Folge verbessert; und liegt deutlich über dem langfristigen Durchschnitt. Die Expansion der Weltwirtschaft wird im Prognosezeitraum schwungvoll bleiben, sich jedoch schrittweise etwas abflachen. Die Konjunktur in Deutschland zeigt sich zur Jahresmitte 2006 gut in Form. Das hervorragende ifo Geschäftsklima indiziert, dass der Aufschwung der deutschen Wirtschaft beträchtlich an Breite gewonnen hat. Neben dem mit hoher Drehzahl laufenden Exportmotor ist nun auch die Binnenkonjunktur in Schwung gekommen. Die Investitionen in Ausrüstungen haben Tritt gefasst; die neuesten Zahlen des ifo Konjunkturtests signalisieren, dass nicht nur die im Sog des Exportbooms stehenden Unternehmen investieren, sondern nun auch die eher binnenwirtschaftlich orientierten Unternehmen. Selbst der private Konsum hat, nach dem Rückgang im Jahresendquartal 2005, zugelegt; zusätzliche Impulse werden in der zweiten Jahreshälfte von vorgezogenen Käufen ausgehen, mit denen die ab Januar kommenden Jahres geltende höhere Mehrwertsteuer kurzfristig noch eingespart werden kann. Ingesamt wird das reale Bruttoinlandsprodukt im laufenden Jahr um 1,8% expandieren; nach Ausschaltung der im Vergleich zu 2005 geringeren Zahl an Arbeitstagen um 2%. Im kommenden Jahr wird die Konjunktur durch die massive Erhöhung von Steuern und Abgaben zwar beträchtlich gedämpft; gleichwohl wird sich aber der Aufschwung fortsetzen. Diese Einschätzung stützt sich zu einem großen Teil auf die endogene Konjunkturdynamik der deutschen Wirtschaft. Nach einem "klassischen" Abschwung in den ersten Jahren dieses Jahrzehnts, der von einem Rückgang der Trendwachstumsrate begleitet war, wurde sowohl bei der gesamtwirtschaftlichen Produktion als auch bei den Ausrüstungsinvestitionen im Laufe des Jahres 2004 der untere Wendepunkt erreicht.Weltkonjunktur, Konjunkturprognose, Wirtschaftslage, Wirtschaftswachstum, Geschäftsklima, Deutschland, Welt

I-BEAT: New ultrasonic method for single bunch measurement of ion energy distribution

The shape of a wave carries all information about the spatial and temporal structure of its source, given that the medium and its properties are known. Most modern imaging methods seek to utilize this nature of waves originating from Huygens' principle. We discuss the retrieval of the complete kinetic energy distribution from the acoustic trace that is recorded when a short ion bunch deposits its energy in water. This novel method, which we refer to as Ion-Bunch Energy Acoustic Tracing (I-BEAT), is a generalization of the ionoacoustic approach. Featuring compactness, simple operation, indestructibility and high dynamic ranges in energy and intensity, I-BEAT is a promising approach to meet the needs of petawatt-class laser-based ion accelerators. With its capability of completely monitoring a single, focused proton bunch with prompt readout it, is expected to have particular impact for experiments and applications using ultrashort ion bunches in high flux regimes. We demonstrate its functionality using it with two laser-driven ion sources for quantitative determination of the kinetic energy distribution of single, focused proton bunches.Comment: Paper: 17 Pages, 3 figures Supplementary Material 16 pages, 7 figure

Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions

Significant reductions in stratospheric ozone occur inside the polar vortices each spring when chlorine radicals produced by heterogeneous reactions on cold particle surfaces in winter destroy ozone mainly in two catalytic cycles, the ClO dimer cycle and the ClO/BrO cycle. Chlorofluorocarbons (CFCs), which are responsible for most of the chlorine currently present in the stratosphere, have been banned by the Montreal Protocol and its amendments, and the ozone layer is predicted to recover to 1980 levels within the next few decades. During the same period, however, climate change is expected to alter the temperature, circulation patterns and chemical composition in the stratosphere, and possible geo-engineering ventures to mitigate climate change may lead to additional changes. To realistically predict the response of the ozone layer to such influences requires the correct representation of all relevant processes. The European project RECONCILE has comprehensively addressed remaining questions in the context of polar ozone depletion, with the objective to quantify the rates of some of the most relevant, yet still uncertain physical and chemical processes. To this end RECONCILE used a broad approach of laboratory experiments, two field missions in the Arctic winter 2009/10 employing the high altitude research aircraft M55-Geophysica and an extensive match ozone sonde campaign, as well as microphysical and chemical transport modelling and data assimilation. Some of the main outcomes of RECONCILE are as follows: (1) vortex meteorology: the 2009/10 Arctic winter was unusually cold at stratospheric levels during the six-week period from mid-December 2009 until the end of January 2010, with reduced transport and mixing across the polar vortex edge; polar vortex stability and how it is influenced by dynamic processes in the troposphere has led to unprecedented, synoptic-scale stratospheric regions with temperatures below the frost point; in these regions stratospheric ice clouds have been observed, extending over >106km2 during more than 3 weeks. (2) Particle microphysics: heterogeneous nucleation of nitric acid trihydrate (NAT) particles in the absence of ice has been unambiguously demonstrated; conversely, the synoptic scale ice clouds also appear to nucleate heterogeneously; a variety of possible heterogeneous nuclei has been characterised by chemical analysis of the non-volatile fraction of the background aerosol; substantial formation of solid particles and denitrification via their sedimentation has been observed and model parameterizations have been improved. (3) Chemistry: strong evidence has been found for significant chlorine activation not only on polar stratospheric clouds (PSCs) but also on cold binary aerosol; laboratory experiments and field data on the ClOOCl photolysis rate and other kinetic parameters have been shown to be consistent with an adequate degree of certainty; no evidence has been found that would support the existence of yet unknown chemical mechanisms making a significant contribution to polar ozone loss. (4) Global modelling: results from process studies have been implemented in a prognostic chemistry climate model (CCM); simulations with improved parameterisations of processes relevant for polar ozone depletion are evaluated against satellite data and other long term records using data assimilation and detrended fluctuation analysis. Finally, measurements and process studies within RECONCILE were also applied to the winter 2010/11, when special meteorological conditions led to the highest chemical ozone loss ever observed in the Arctic. In addition to quantifying the 2010/11 ozone loss and to understand its causes including possible connections to climate change, its impacts were addressed, such as changes in surface ultraviolet (UV) radiation in the densely populated northern mid-latitudes

I-BEAT: Ultrasonic method for online measurement of the energy distribution of a single ion bunch

The shape of a wave carries all information about the spatial and temporal structure of its source, given that the medium and its properties are known. Most modern imaging methods seek to utilize this nature of waves originating from Huygens' principle. We discuss the retrieval of the complete kinetic energy distribution from the acoustic trace that is recorded when a short ion bunch deposits its energy in water. This novel method, which we refer to as Ion-Bunch Energy Acoustic Tracing (I-BEAT), is a refinement of the ionoacoustic approach. With its capability of completely monitoring a single, focused proton bunch with prompt readout and high repetition rate, I-BEAT is a promising approach to meet future requirements of experiments and applications in the field of laser-based ion acceleration. We demonstrate its functionality at two laser-driven ion sources for quantitative online determination of the kinetic energy distribution in the focus of single proton bunches

Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions : (RECONCILE) ; activities and results

The international research project RECONCILE has addressed central questions regarding polar ozone depletion, with the objective to quantify some of the most relevant yet still uncertain physical and chemical processes and thereby improve prognostic modelling capabilities to realistically predict the response of the ozone layer to climate change. This overview paper outlines the scope and the general approach of RECONCILE, and it provides a summary of observations and modelling in 2010 and 2011 that have generated an in many respects unprecedented dataset to study processes in the Arctic winter stratosphere. Principally, it summarises important outcomes of RECONCILE including (i) better constraints and enhanced consistency on the set of parameters governing catalytic ozone destruction cycles, (ii) a better understanding of the role of cold binary aerosols in heterogeneous chlorine activation, (iii) an improved scheme of polar stratospheric cloud (PSC) processes that includes heterogeneous nucleation of nitric acid trihydrate (NAT) and ice on non-volatile background aerosol leading to better model parameterisations with respect to denitrification, and (iv) long transient simulations with a chemistry-climate model (CCM) updated based on the results of RECONCILE that better reproduce past ozone trends in Antarctica and are deemed to produce more reliable predictions of future ozone trends. The process studies and the global simulations conducted in RECONCILE show that in the Arctic, ozone depletion uncertainties in the chemical and microphysical processes are now clearly smaller than the sensitivity to dynamic variability

Integrated photonic-based coronagraphic systems for future space telescopes

The detection and characterization of Earth-like exoplanets around Sun-like stars is a primary science motivation for the Habitable Worlds Observatory. However, the current best technology is not yet advanced enough to reach the 10^-10 contrasts at close angular separations and at the same time remain insensitive to low-order aberrations, as would be required to achieve high-contrast imaging of exo-Earths. Photonic technologies could fill this gap, potentially doubling exo-Earth yield. We review current work on photonic coronagraphs and investigate the potential of hybridized designs which combine both classical coronagraph designs and photonic technologies into a single optical system. We present two possible systems. First, a hybrid solution which splits the field of view spatially such that the photonics handle light within the inner working angle and a conventional coronagraph that suppresses starlight outside it. Second, a hybrid solution where the conventional coronagraph and photonics operate in series, complementing each other and thereby loosening requirements on each subsystem. As photonic technologies continue to advance, a hybrid or fully photonic coronagraph holds great potential for future exoplanet imaging from space.Comment: Conference Proceedings of SPIE: Techniques and Instrumentation for Detection of Exoplanets XI, vol. 12680 (2023

Visible extreme adaptive optics on extremely large telescopes: Towards detecting oxygen in Proxima Centauri b and analogs

Looking to the future of exo-Earth imaging from the ground, core technology developments are required in visible extreme adaptive optics (ExAO) to enable the observation of atmospheric features such as oxygen on rocky planets in visible light. UNDERGROUND (Ultra-fast AO techNology Determination for Exoplanet imageRs from the GROUND), a collaboration built in Feb. 2023 at the Optimal Exoplanet Imagers Lorentz Workshop, aims to (1) motivate oxygen detection in Proxima Centauri b and analogs as an informative science case for high-contrast imaging and direct spectroscopy, (2) overview the state of the field with respect to visible exoplanet imagers, and (3) set the instrumental requirements to achieve this goal and identify what key technologies require further development.Comment: SPIE Proceeding: 2023 / 12680-6