Gravity waves, scale asymptotics, and the pseudo-incompressible equations

Multiple-scale asymptotics is used to analyze the Euler equations for the dynamical situation of a gravity wave (GW) near breaking level. A simple saturation argument in combination with linear theory is used to obtain the relevant dynamical scales. As small expansion parameter the ratio of inverse of the vertical wave number and potentialtemperature and pressure scale heights is used, which we allow to be of the same order of magnitude here. It is shown that the resulting equation hierarchy is consistent with that obtained from the pseudo-incompressible equations, both for non-hydrostatic and hydrostatic gravity waves, while this is not the case for the anelastic equations unless the additional assumption of sufficiently weak stratication is adopted. To describe vertical propagation of wave packets over several atmospheric scale heights, WKB theory is used to show that the pseudo-incompressible flow divergence generates the same amplitude equation that also obtains from the full Euler equations. This gives a mathematical justication for the use of the pseudo-incompressible equations for studies of gravity-wave breaking in the atmosphere for arbitrary background stratication. The WKB theory interestingly also holds at wave amplitudes close to static instability. In the mean-flow equations we obtain in addition to the classic wave-induced momentum-flux divergences a wave-induced correction of hydrostatic balance in the vertical-momentum equation which cannot be obtained from Boussinesq or anelastic dynamics

The interaction between synoptic-scale balanced flow and a finite-amplitude mesoscale wave field throughout all atmospheric layers: weak and moderately strong stratification

The interaction between locally monochromatic finite-amplitude mesoscale waves, their nonlinearly induced higher harmonics, and a synoptic-scale flow is reconsidered, both in the tropospheric regime of weak stratification and in the stratospheric regime of moderately strong stratification. A review of the basic assumptions of quasi-geostrophic theory on an f-plane yields all synoptic scales in terms of a minimal number of natural variables, i.e. two out of the speed of sound, gravitational acceleration and Coriolis parameter. The wave scaling is defined so that all spatial and temporal scales are shorter by one order in the Rossby number, and by assuming their buoyancy field to be close to static instability. WKB theory is applied, with the Rossby number as scale separation parameter, combined with a systematic Rossby-number expansion of all fields. Classic results for synoptic-scale-flow balances and inertia-gravity-wave (IGW) dynamics are recovered. These are supplemented by explicit expressions for the interaction between mesoscale geostrophic modes (GMs), a possibly somewhat overlooked agent of horizontal coupling in the atmosphere, and the synoptic-scale flow. It is shown that IGW higher harmonics are slaved to the basic IGW, and that their amplitude is one order of magnitude smaller than the basic-wave amplitude. GM higher harmonics are not that weak and they are in intense nonlinear interaction between themselves and the basic GM. Compressible dynamics plays a significant role in the stratospheric stratification regime, where anelastic theory would yield insufficient results. Supplementing classic derivations, it is moreover shown that, in the absence of mesoscale waves, quasi-geostrophic theory holds also in the stratospheric stratification regime

Globally consistent climate sensitivity of natural disturbances across boreal and temperate forest ecosystems

Disturbance regimes are changing in forests across the world in response to global climate change. Despite the profound impacts of disturbances on ecosystem services and biodiversity, assessments of disturbances at the global scale remain scarce. Here, we analyzed natural disturbances in boreal and temperate forest ecosystems for the period 2001-2014, aiming to 1) quantify their within- and between-biome variation and 2) compare the climate sensitivity of disturbances across biomes. We studied 103 unmanaged forest landscapes with a total land area of 28.2 x 10(6) ha, distributed across five continents. A consistent and comprehensive quantification of disturbances was derived by combining satellite-based disturbance maps with local expert knowledge of disturbance agents. We used Gaussian finite mixture models to identify clusters of landscapes with similar disturbance activity as indicated by the percent forest area disturbed as well as the size, edge density and perimeter-area-ratio of disturbed patches. The climate sensitivity of disturbances was analyzed using Bayesian generalized linear mixed effect models and a globally consistent climate dataset. Within-biome variation in natural disturbances was high in both boreal and temperate biomes, and disturbance patterns did not vary systematically with latitude or biome. The emergent clusters of disturbance activity in the boreal zone were similar to those in the temperate zone, but boreal landscapes were more likely to experience high disturbance activity than their temperate counterparts. Across both biomes high disturbance activity was particularly associated with wildfire, and was consistently linked to years with warmer and drier than average conditions. Natural disturbances are a key driver of variability in boreal and temperate forest ecosystems, with high similarity in the disturbance patterns between both biomes. The universally high climate sensitivity of disturbances across boreal and temperate ecosystems indicates that future climate change could substantially increase disturbance activity.Peer reviewe

The impact of mineral dust on cloud formation during the Saharan dust event in April 2014 over Europe

A regional modeling study on the impact of desert dust on cloud formation is presented for a major Saharan dust outbreak over Europe from 2 to 5 April 2014. The dust event coincided with an extensive and dense cirrus cloud layer, suggesting an influence of dust on atmospheric ice nucleation. Using interactive simulation with the regional dust model COSMO-MUSCAT, we investigate cloud and precipitation representation in the model and test the sensitivity of cloud parameters to dust–cloud and dust–radiation interactions of the simulated dust plume. We evaluate model results with ground-based and spaceborne remote sensing measurements of aerosol and cloud properties, as well as the in situ measurements obtained during the ML-CIRRUS aircraft campaign. A run of the model with single-moment bulk microphysics without online dust feedback considerably underestimated cirrus cloud cover over Germany in the comparison with infrared satellite imagery. This was also reflected in simulated upper-tropospheric ice water content (IWC), which accounted for only 20&thinsp;% of the observed values. The interactive dust simulation with COSMO-MUSCAT, including a two-moment bulk microphysics scheme and dust–cloud as well as dust–radiation feedback, in contrast, led to significant improvements. The modeled cirrus cloud cover and IWC were by at least a factor of 2 higher in the relevant altitudes compared to the noninteractive model run. We attributed these improvements mainly to enhanced deposition freezing in response to the high mineral dust concentrations. This was corroborated further in a significant decrease in ice particle radii towards more realistic values, compared to in situ measurements from the ML-CIRRUS aircraft campaign. By testing different empirical ice nucleation parameterizations, we further demonstrate that remaining uncertainties in the ice-nucleating properties of mineral dust affect the model performance at least as significantly as including the online representation of the mineral dust distribution. Dust–radiation interactions played a secondary role for cirrus cloud formation, but contributed to a more realistic representation of precipitation by suppressing moist convection in southern Germany. In addition, a too-low specific humidity in the 7 to 10&thinsp;km altitude range in the boundary conditions was identified as one of the main reasons for misrepresentation of cirrus clouds in this model study.</p

A unified model for BAM function that takes into account type Vc secretion and species differences in BAM composition

Transmembrane proteins in the outer membrane of Gram-negative bacteria are almost exclusively β-barrels. They are inserted into the outer membrane by a conserved and essential protein complex called the BAM (for β-barrel assembly machinery). In this commentary, we summarize current research into the mechanism of this protein complex and how it relates to type V secretion. Type V secretion systems are autotransporters that all contain a β-barrel transmembrane domain inserted by BAM. In type Vc systems, this domain is a homotrimer. We argue that none of the current models are sufficient to explain BAM function particularly regarding type Vc secretion. We also find that current models based on the well-studied model system Escherichia coli mostly ignore the pronounced differences in BAM composition between different bacterial species. We propose a more holistic view on how all OMPs, including autotransporters, are incorporated into the lipid bilayer

Partial photoionization cross-sections at the 3d thresholds of rare earth metals

In Nd, Sm, Eu and Gd the decay of the 3d-4f resonance excitation into different photo ionization channels (4f, 4d) was measured. Spin-orbit splitting of the 3d hole dominates the spectra. Depopulation of the 3d$_3$$_2$ due to the M$_4$M$_5$N$_5$$_7$ Auger effect leads to a much larger 3d$_5$$_2$:3d$_3$$_2$ int than in absorption. The use of synchrotron radiation from an undulation was decisive

A quantitative analysis of the effects of heat loading on an undulator beamline

With the help of several computer codes especially developed or adapted for this application, the energy losses in the individual components of a high resolution undulator beamline for BESSY II were quantitatively calculated and their effect on the performance of the beamline determined. The critical portion of the beamline, a Kirkpatrick-Baez system in front of the entrance slit, can be designed so as to withstand the deleterious effects of the heat loading with essentially no loss of intrinsic brightness of the source. The absorbed heat load profile has been determined in a dense grid on the mirror surfaces by taking the variation of the spectral power distribution from the undulator and the reflectivity of the surfaces into account. The influence of the angle of incidence on the first horizontally deflecting mirror as well as of a vertical aperture in front of the beamline has been studied. The temperature and stress analysis was performed using the finite element method while, the effect of the surface displacements on the optical properties of the beamline was analysed with raytraces. Using SiC mirrors with a simple side cooling and by eliminating the unwanted radiation before it reaches the first optical element it is possible to conserve 90% of the brilliance of the source all the way through to the experiment. Maximum absorbed power densities of 0.27 W/mm&quot;2 on the first and 0.024 W/mm&quot;2 on the second mirror are calculated and have almost no effect on the performance of the beamline. (orig.)SIGLEAvailable from TIB Hannover: RO 8093(176) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Smart Fabrication QM - Neue Produktionskonzepte fuer die Halbleiterfertigung. Qualitaetsmanagement fuer neue Produktionskonzepte Abschlussbericht

The partners within the research cooperation with the IC manufactures BOSCH, SIEMENS, TEMIC, THESYS (X-Fab) and ZMD as well as the FhG. The objective of the cooperation was to find new and advanced methods for quality and reliability purposes for semiconductor fabs. Within the dynamic and fast changing market of ASICs, quick and flexible development and production times combined with quality ensuring actions are the keys of economy. The cooperation aimed to work out methods for a flexible, fast, and favourable quality assurance especially for ASICs in a 3 years industrial research and development project useful for all project partners. Detailed investigations in the areas of wafer level monitoring, reliability tests on typical circuit elements, development of optimised qualification procedures, and the work for / analyses of defect management strategies bred great experiences for all partners and gave the start for different new approaches for further optimisation actions. (orig.)SIGLEAvailable from TIB Hannover: F00B452 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

Is there a benefit from intensified medical and psychological interventions in patients with functional dyspepsia not responding to conventional therapy?

The definitive version is available at www.blackwell-synergy.com Article first published online: 12 FEB 2007Aim: In a prospective randomized, controlled trial, to compare the long-term outcome of intensive medical therapy (with or without cognitive-behavioural or muscle relaxation therapy) vs. standard medical therapy in patients with refractory functional dyspepsia (FD), referred to a tertiary referral medical center. Methods: A total of 100 consecutive FD patients were allocated to a standardized symptom-oriented 4 month therapy (SMT, n = 24), intensive medical therapy (IMT, medical therapy with testing-for and targeting-of abnormalities of motor-and-sensory function, n = 28) or IMT plus psychological interventions (either progressive-muscle relaxation (IMT-MR, n = 20) or cognitive-behavioural therapy (IMT-CBT, n = 28). The symptom intensity (SI) and health-related quality-of-life (HRQoL) after 12 months were prespecified primary outcome parameters. Results: After 12 months, significantly greater improvement of SI occurred in patients with IMT-all (with or without psychological interventions) compared with SMT (P &lt; 0.025 vs. IMT-all). IMT, IMT-MR and IMT-CBT alone also resulted in significantly better improvement of the primary outcome parameters (P all &lt; 0.025 vs. SMT). HRQoL significantly improved in all groups with intensive medical therapy but not standard medical therapy. Differences between intensive medical therapy-all and standard medical therapy were not significant. Concomitant anxiety and depression was improved significantly by IMT-CBT (vs. SMT) but not other treatments. Conclusions: In FD patients with refractory symptoms, intensified medical management involving function testing and psychological intervention yields superior long-term-outcomes. Additional CBT may be effective for the control of concomitant anxiety and depression.S. Haag, W. Senf, S. Tagay, M. Langkafel, U. Braun-Lang, A. Pietsch, G. Heuft, N. J. Talley and G. Holtman