bluuebunny/crossref_metadata_2025 huggingface dataset:
Interpretations of the total energy and rotational energy norms applied to determination of singular vectors
Authors: Errico Ronald M.
Published: August 2010

The interpretation of the commonly‐used energy norm is examined in the context of a simple vertically‐discrete model. The norm is shown to include expressions for kinetic and available potential energy in addition to an expression for a portion of unavailable potential energy. Another norm is then introduced that only includes the rotational‐mode contribution to these. The characterization of the two norms in terms of corresponding covariance functions is shown to be quite different, with that for the latter norm looking more like prior error statistics used in synoptic‐scale data assimilation. The leading singular vectors are determined for both norms. Those computed for the new norm have slower associated growth. Their corresponding structures are similar at the initial time, however, with some notable differences, but after 24 hours their shapes are almost identical. The new norm has advantages over the old norm for some applications; e.g. for effectively filtering ageostrophic, convectively‐driven singular vectors and for being more consistent with a spatially and dynamically correlated error norm.
The dynamical balance of leading singular vectors in a primitive‐equation model
Authors: Errico Ronald M.
Published: August 2010

The dynamical balance of singular vectors (SVs) determined with respect to an energy norm for a primitive‐equation atmospheric model is investigated. Partitioning between balanced and unbalanced components is primarily performed in terms of geostrophic and ageostrophic normal modes. Results indicate that if linearized effects of moist convection are not considered, the initial structure of the leading (most rapidly growing) SV is primarily geostrophic, although the ageostrophic part is significant. At the concluding time, however, the structure is almost totally geostrophic. The initially uncorrelated geostrophic and ageostrophic portions of the SV separately evolve into highly correlated structures. These two separately evolved portions therefore reinforce each other, so that the sum of the concluding total perturbation energies of the two portions is less than the corresponding energy of the non‐partitioned SV. The high correlations also suggest that the inverse of the tangent linear model would be ill‐suited for estimating an initial perturbation given an imperfectly known final one. There is no hint of significant high‐frequency inertial gravity‐wave activity.
Dynamical impact of total‐ozone observations in a four‐dimensional variational assimilation
Authors: Peuch A. , Thépaut J.‐N. , Pailleux J.
Published: August 2010

Observing‐system simulation experiments (OSSEs) are performed to investigate the dynamical impact of total‐ozone data used in a four‐dimensional variational analysis in a numerical weather prediction (NWP) model. Ozone columns are generated by the model at the location of data retrieved by the National Environmental Satellite, Data, and Information Service, from the measurements of the TIROS (Television Infra‐Red Observation Satellite) Operational Vertical Sounder (TOVS). They are assimilated over a 12‐hour period. In the present experiments, ozone mixing ratio is considered to be a passive tracer, simply advected by winds. The initial three‐dimensional ozone field is not analysed. An important positive impact is found in a fully idealized experiment, on the flow analysis as well as on the temperature analysis. The ability to derive thermodynamic information from ozone‐column observations is confirmed by an OSSE performed in a more realistic context. Moreover, the information on wind fields supplied by ozone data may be in addition to the information already provided by observations currently assimilated in NWP models. Some conditions, needed to make the information provided by ozone columns effective, are discussed, such as the accuracy of the ozone measurements and the necessity of analysing ozone in addition to the usual model variables.
Retrieving temperature, water vapour and surface pressure information from refractive‐index profiles derived by radio occultation: A simulation study
Authors: Healy S. B. , Eyre J. R.
Published: August 2010

A one‐dimensional variational retrieval for the assimilation of refractive‐index profiles derived from radio occultation (RO) measurements has been developed. The method is tested by using simulated data to assess the retrieval accuracy and information content of the measurements, using various realistic estimates for the assumed error distributions. Theoretical retrieval‐error estimates given by a solution covariance matrix are in good qualitative agreement with those derived statistically from the comparison of the solution profiles with the precisely defined ‘true’ values. It is demonstrated that the ‘water vapour ambiguity’ inherent in more conventional RO inversion methods is resolved with this approach. It is found that the solution x2values, quantifying the fit to the observed refractivities and a priori profile estimates, are in good agreement with the theoretical distribution, suggesting that they could be used for quality‐control purposes. Furthermore, it is shown that the measurements contain significant surface pressure information. This arises through the hydrostatic relationship, as a result of mapping the state‐vector information on pressure levels to height coordinates. The simulations indicate that the measurements in the tropics contain the greatest surface pressure information, with a reduction of the background error of ∼45%. This new result has significance for the design of future observing systems.
Evaluation of a cloud system life‐cycle simulated by the Meso‐NH model during FASTEX using METEOSAT radiances and TOVS‐3I cloud retrievals
Authors: Chaboureau Jean‐Pierre , Cammas Jean‐Pierre , Mascart Patrick , Pinty Jean‐Pierre , Claud Chantal , Roca Remy , Morcrette Jean‐Jacques
Published: August 2010

The evaluation of a simulation over the life‐cycle of a cloud system during the Fronts and Atlantic Storm‐Track EXperiment is made by comparing synthetic and METEOSAT observed radiances. The usefulness of a ‘model‐to‐satellite’ approach, combining an explicit cloud scheme implemented in a mesoscale model (the Meso‐NH model) with a detailed radiative‐transfer code, is shown. In clear sky, accuracy in the brightness‐temperature simulations are, respectively, about 4.5 K for the infrared channel and 2 K for the water‐vapour channel. In cloudy areas, comparison with the TOVS‐3I cloud parameters shows that these errors become twice as large. The occurrence of key patterns in the simulated infrared images confirms the good quality of the model forecast and the accuracy of the radiative code. On the other hand, the discrepancies identified by the approach show that the model overestimates the upper‐level cloud cover. It is suggested that this overestimation might result either from a too large water detrainment or from an overestimated water residence time in the upper atmosphere. Finally, using an ice‐phase parametrization in the cloud scheme significantly improves the simulated cloud cover, although this more advanced scheme does not correct the overestimation of upper‐level cloud cover.
Quantification of isentropic water‐vapour transport into the lower stratosphere
Authors: Dethof A. , O'Neill A. , Slingo J. M. , Berrisford P.
Published: August 2010

The contour advection technique is used to quantify the quasi‐horizontal isentropic transport of water vapour across the tropopause between the tropical upper troposphere and the extratropical lower stratosphere. The calculations are based on European Centre for Medium‐Range Weather Forecasts analyses for 1997 and 1998. It is found that the isentropic transport of water vapour into the extratropical lower stratosphere has a similar magnitude to the upward (cross‐isentropic) transport of water vapour into the stratosphere in the tropics. The isentropic flux is largest during summer, and is more than enough to account for the observed summertime increase in specific humidity in the lowermost stratosphere. The annual isentropic moisture transport into the extratropical lower stratosphere in the northern hemisphere is about one order of magnitude larger than that in the southern hemisphere. This difference in transport explains why the extratropical lower stratosphere is moister in the northern hemisphere during northern summer than it is in the southern hemisphere during southern summer. The results further show that there was more moisture transport into the lower stratosphere of both hemispheres during 1998, under El Niño conditions, than during 1997.
Marine stratus clouds: Changing liquid‐water and temperature structure
Authors: Telford J. W.
Published: August 2010

Aircraft measurements with the Wyoming King Air investigated the response of marine stratus clouds off the north California coast, advected to regions with changed sea surface temperature in coastal upwelling. Cloud and associated clear‐air observations were made before and near sunrise to eliminate any role of solar heating. Repeated vertical soundings followed temporal advected air. Subcloud structure was observed for the presence of moist convection, reported below clouds in some conditions. The atmospheric structure in the clear air above the marine stratus cloud layer showed shallow layers having large temperature gradients with height, apparently remaining from an earlier decoupled overlying cloud layer. Such gradients appear to be associated with thermal radiative‐heat transfer in the clear air. Cloud tops were observed to be mostly warmer than the cloud just below. It is suggested that a large temperature increase over a small height difference at the cloud‐top inversion may serve to neutralize radiative cooling of the cloud drops below, occurring through the atmospheric thermal radiative window.

Observations show that subcloud air is often stable to dry convection. This is not evidence that there is decoupling from the sea surface, since there is no wind shear in the layer and moisture continually moves upwards. Subcloud convection from the sea appears to continue everywhere, demonstrated by the rise of intermittent patches of condensation. Such clouds are found below the stratus deck after passage over cooler water, and are clearly responsible for the upward transport of moisture.

These transfer processes have been shown to influence cloud‐drop spectra and liquid‐water content in the clouds as well as the growth and dissipation of stratus clouds. It is concluded that high spatial‐resolution (less than a few metres) measurements of vertical radiative‐flux divergence are required to confirm the importance of the overlying warmer region in the overall heat balance of a stratiform cloud.
Asymptotic approaches to convective quasi‐equilibrium
Authors: Yano Jun‐Ichi , Roff Gregory L. , Grabowski Wojciech W. , Mapes Brian E.
Published: August 2010

The physical principle of convective quasi‐equilibrium proposed by Arakawa and Schubert states that the atmosphere is effectively adjusted to equilibrium by an active role of convective heating against large‐scale forcing (physical convective quasi‐equilibrium, or PCQ). A simple consequence of this principle is that the rate of change of the thermodynamic field (typically measured by the convective available potential energy (CAPE)) is much smaller than the rate of change of the large‐scale forcing (diagnostic convective quasi‐equilibrium, or DCQ). Such a diagnostic state is generally observed in the tropical atmosphere at the synoptic‐scale, and this is often taken as a proof for the physical mechanisms behind Arakawa and Schubert's convective quasi‐equilibrium: however, theoretically, there are several alternative physical mechanisms that are also able to establish this diagnostic state.

The paper examines the approach of the tropical atmospheric system to DCQ with increasing time‐scale in order to distinguish various alternatives to PCQ. The latter predicts that the system approaches DCQ exponentially with a time‐scale characteristic of convection. However, the alternatives considered in the paper predict algebraic asymptotes to DCQ with increasing time‐scale. First it is demonstrated that PCQ is not required to achieve DCQ by considering a linear primitive‐equation system with arbitrary convective heating, in which the roles of convective heating and large‐scale forcing are completely reversed; algebraic asymptotes are achieved. An even simpler analogue is to assume that the rate of generating CAPE is controlled by white‐noise forcing. More generally, such an algebraic asymptote is obtained by any system with a power‐law spectrum both for CAPE and large‐scale forcing, although a restriction must be applied to ensure a decreasing asymptote with increasing time‐scale.

The approach to DCQ is examined for both the Maritime Continent Thunderstorm Experiment data and cloud‐resolving model simulation data, and both indicate no tendency for exponential adjustments in the short time limit.
Turbulent length‐scales in the marine atmospheric mixed layer
Authors: Durand P. , Thoumieux F. , Lambert D.
Published: August 2010

The spectra of turbulence signals can be characterized by several independent scales. To provide a parametrization of these spectra requires knowledge of the relationships between these scales. This paper focuses on three independent scales: the integral scale (which is influenced by the low‐frequency behaviour of the spectra); the wavelength of the spectrum peak (which characterizes the energy‐containing domain); and the dissipation scale (which is relevant for the inertial subrange). First, we present definitions of these various scales, and the possible relationships between them. The profiles of the scales were computed from airborne measurements made in the atmospheric mixed layer over the open ocean, in a region where horizontal homogeneity can be assumed, at least for several tens of km. Furthermore, the diurnal cycle being very weak in this oceanic area, and aircraft moving at high speed through the air mass, stationarity is well verified on the runs, and Taylor's hypothesis may be used. The meteorological conditions correspond to a slightly unstable mixed layer, with weak to moderate winds. In a first part, we analyse the integral scales of various parameters on a 180‐km run and demonstrate that these parameters cannot be computed with any soundness from horizontal‐wind, temperature and moisture signals, because of the continuous increase in the spectral energy when moving towards lower frequencies. For the same reasons, the spectrum peak and the corresponding wavelength cannot be determined for these parameters. The computation of the integral and energy‐containing scale is therefore restricted to the vertical velocity, and to the various covariances. The turbulence field is characterized by a stretching of the eddies along the mean wind direction which results in greater integral and energy‐containing scales (but not in greater dissipation scales) when computed for along‐wind runs than for the cross‐wind runs. The profiles of the various scales increase with altitude and are well defined in the lower half of the mixed layer, but are much more scattered in the upper half. This behaviour is related to the source of turbulence, which lies in the surface buoyancy flux in the lower half of the mixed layer, and comes from higher altitude sources in the upper half. The integral scales have values comparable with those found in previous work, except for parameters related to temperature fluctuations, which have lower values. The ratio of the energy‐containing scale to the integral scale, which determines the sharpness of the ‘spectral knee’, varies considerably from one parameter to another, and sometimes with altitude. This demonstrates that a single unique parametrization cannot be defined for turbulence spectra. As a consequence, the eddy‐exchange coefficients, which depend on a characteristic length‐scale, should vary from one parameter to another. This would then have to be taken into account in model parametrization based on mixing length‐scales.
Smooth solutions and attractor dimension bounds for planetary geostrophic ocean models
Authors: Samelson R. , Temam R. , Wang S.
Published: August 2010

Recent results on the existence and uniqueness of global strong solutions of the planetary geostrophic model of large‐scale ocean circulation, with traditional parametrizations of horizontal and vertical diffusion of heat and horizontal momentum, are summarized. The new results are stronger than existing results for the hydrostatic primitive equations. A rigorous upper bound on attractor dimension for the planetary geostrophic model is presented, which scales as the cube of the product of the Reynolds number Re and the Péclet number Pe, or as Re3/2· Pe9/4if some additional assumptions are made. The dimension bound demonstrates that the model dynamics are controlled asymptotically by a finite number of effective degrees of freedom, and raises new physical questions regarding the associated estimate of this number. Available numerical evidence appears to indicate that, in contrast to analogous results for homogeneous turbulence described by the Navier‐Stokes equations, substantial improvements to these bounds may be possible.
A planetary‐scale land–sea breeze circulation in East Asia and the western North Pacific
Authors: Huang Wan‐Ru , Chan Johnny C. L. , Wang Shih‐Yu
Published: August 2010

The diurnal wind variation over the East Asian continent is commonly considered to be a combination of a land‐sea breeze near the coast and a mountain–valley breeze along the slopes of the Tibetan Plateau. The local land–sea breeze along the coastline typically spans < 100 km into the ocean. However, a detailed examination of the global reanalysis data suggests that this local land–sea breeze circulation apparently couples with the global‐scale diurnal atmospheric pressure tide to produce a planetary‐scale land–sea breeze with a spatial scale of ∼1000 km over the western North Pacific. Computations of the momentum budget and equivalent potential temperatures indicate that the atmospheric diurnal tidal wave contributes the most to this circulation feature. A diagnosis of the water vapour budget further suggests that the convergence of water vapour flux, which is related to the convergence of low‐level wind induced by the seasonal change of diurnal tidal wave, leads to different times of occurrence of maximum diurnal rainfall over East Asia between summer and winter. Copyright © 2010 Royal Meteorological Society
Tetrakis(4‐sulfonatophenyl)porphyrin‐Directed Assembly of Gold Nanocrystals: Tailoring the Plasmon Coupling Through Controllable Gap Distances
Authors: Zhang Li , Chen Huanjun , Wang Jianfang , Li Yuan Fang , Wang Jian , Sang You , Xiao Sai Jin , Zhan Lei , Huang Cheng Zhi
Published: August 2010

It is known that universality and controllability over nanocrystal orientation must be accomplished to facilitate the potential applications of metal nanocrystals in the areas of photonics, electronics, and optics. The facile fabrication of linear chains of Au nanorods and bifurcated junctions of nanorods/nanospheres is achieved via the crosslinking of H‐type tetrakis(4‐sulfonatophenyl)porphyrin aggregates in solution. The tuning of the plasmon coupling between the Au nanocrystals is demonstrated by varying the porphyrin concentration and thus the interparticle gap distances. Finite‐difference time‐domain calculations show that the red shift of the plasmon band exhibits a nearly exponential decay with increasing interparticle gap distances, thus giving rise to a “plasmon ruler equation.” The gap distances determined according to this equation agree well with the experimental observations and further confirm the porphyrin‐directed assembly process. The interaction mechanism between the Au nanorods and porphyrins is further investigated by a biological procedure using the dark‐field light scattering technique.
Transistors Formed from a Single Lithography Step Using Information Encoded in Topography
Authors: Dickey Michael D. , Russell Kasey J. , Lipomi Darren J. , Narayanamurti Venkatesh , Whitesides George M.
Published: August 2010

This paper describes a strategy for the fabrication of functional electronic components (transistors, capacitors, resistors, conductors, and logic gates but not, at present, inductors) that combines a single layer of lithography with angle‐dependent physical vapor deposition; this approach is named topographically encoded microlithography (abbreviated as TEMIL). This strategy extends the simple concept of ‘shadow evaporation’ to reduce the number and complexity of the steps required to produce isolated devices and arrays of devices, and eliminates the need for registration (the sequential stacking of patterns with correct alignment) entirely. The defining advantage of this strategy is that it extracts information from the 3D topography of features in photoresist, and combines this information with the 3D information from the angle‐dependent deposition (the angle and orientation used for deposition from a collimated source of material), to create ‘shadowed’ and ‘illuminated’ regions on the underlying substrate. It also takes advantage of the ability of replica molding techniques to produce 3D topography in polymeric resists. A single layer of patterned resist can thus direct the fabrication of a nearly unlimited number of possible shapes, composed of layers of any materials that can be deposited by vapor deposition. The sequential deposition of various shapes (by changing orientation and material source) makes it possible to fabricate complex structures—including interconnected transistors—using a single layer of topography. The complexity of structures that can be fabricated using simple lithographic features distinguishes this procedure from other techniques based on shadow evaporation.
Fabrication of Carbon Nanoscrolls from Monolayer Graphene
Authors: Xia Dan , Xue Qingzhong , Xie Jie , Chen Huijuan , Lv Cheng , Besenbacher Flemming , Dong Mingdong
Published: August 2010

A simple way of synthesizing carbon nanotube (CNT)/graphene (GN) nanoscroll core/shell nanostructures is demonstrated using molecular dynamics (MD) simulations. The simulations show that GN sheets can fully self‐scroll onto CNTs when the CNT radius is larger than a threshold of about 10 Å, forming a stable core/shell structure. Increasing the length of the GN sheet results in multilayered carbon nanoscroll (CNS) shells that exhibit a tubular structure similar to that of multiwall CNTs. The distances between the CNT and the GN wall or adjacent GN walls are about 3.4 Å. It is found that the van der Waals force plays an important role in the formation of the CNT/GN nanoscroll core/shell‐composite nanostructures. However, the chirality of the CNT and the GN sheet does not affect the self‐scrolling process, which thus provides a simple way of controlling the chirality and physical properties of the resulting core/shell structure. It is expected that this preparation method of CNT/GN nanoscroll core/shell composites will lead to further development of a broad new class of carbon/carbon core/shell composites with enhanced properties and even introduce new functionalities to composite materials.
Statische und kinetische Instabilitäten bei Bauwerken
Authors: Rosemeier Gustav‐Erich
Published: August 2010

In der Bautechnik treten oft, z. B. bei windbelasteten oder meerestechnischen Konstruktionen, statische oder dynamische Instabilitäten auf – manchmal auch ein Zusammenwirken (Interaktion) beider Mechanismen, wobei die Knick‐ oder Beuleigenformen durchaus verschieden von den entsprechenden Schwingungseigenformen sein können. Es soll dargestellt werden, wann die Stabilitätsuntersuchungen der Strukturen statisch durchgeführt werden dürfen und in welcher Form sich die Ergebnisse bei einer zusätzlichen dynamischen Belastung verändern.

Static and dynamic instabilities of structures. In structural design e. g. under wind loads or offshore structures we often have static or dynamic instabilities sometimes also an interaction of both mechanisms, where the buckling modes may be different from the vibration modes. We want to recognize, whether the investigations may be static and how the results may alter by dynamic loads.
Bemessung von Stahlbauten für Anprall‐ und Explosionslasten
Authors: Gündel Max , Hauke Bernhard , Hoffmeister Benno , Feldmann Markus
Published: August 2010

Die zunehmende Gefahr von Anschlägen und Industrieunfällen haben zu neuen Anforderungen an die Auslegung und Bemessung von Bauwerken geführt. Diesen neuen Anforderungen wird derzeit in Normen jedoch nur unzureichend Rechnung getragen. Insbesondere für Bauwerke in Stahl‐ und Verbundbauweise führen die gegenwärtig üblichen Auslegungskonzepte nicht zu wirtschaftlichen Bemessungen. Das bauforumstahl hat daher in Zusammenarbeit mit dem Institut für Stahlbau der RWTH Aachen und HOCHTIEF Construction AG einen Bemessungsleitfaden für Anprall‐ und Explosionslasten erarbeitet, mit dem die Möglichkeiten des Werkstoffes Stahl wesentlich effizienter ausgenutzt werden können. In diesem Beitrag werden die wesentlichen Elemente dieses Leitfadens vorgestellt, der sowohl eine Bewertung von Entwurfsstrategien für robuste Bauwerke enthält, als auch ein Bemessungskonzept zur Auslegung von Stahlbauten gegen spezifische kurzzeit‐dynamische Einwirkungen bereitstellt.

Design of steel structures against impact and blast loads. The increasing threat of terroristic attacks as well as industrial hazards have led to new demands for the conception and design of buildings. Current standards, however, do not provide sufficient guidance to cope with these new requirements. Particularly for steel and composite structures there is a lack of appropriate and therefore economic design concepts. Hence, bauforumstahl in cooperation with the Institute for Steel Structures at RWTH Aachen University and HOCHTIEF Construction AG has published a new design guide to exploit the capabilities of steel more efficiently. This paper presents the main aspects of this design guide. It includes the assessment of strategies for robust structures and a concept to design steel structures against specific high dynamic loads.
Robuste Stahlbauten bei Brandbelastungen
Authors: Zanon Riccardo , May Marc , Cajot Louis‐Guy , Girkes Hans‐Werner
Published: August 2010

In diesem Aufsatz werden die Aspekte des baulichen Brandschutzes vorgestellt, bei denen die Robustheit der Tragkonstruktion eine zentrale Rolle spielt. Erläutert wird das Konzept des kontrollierten Einsturzverhaltens bei eingeschossigen Gebäuden. Außerdem wird die Robustheit von mehrgeschossigen Gebäuden diskutiert und exemplarisch an drei Beispielen vorgestellt.

Robustness of steel constructions under fire load.In this article some applications of fire safety engineering are presented, where the concept of structural robustness plays a major role. First the collapse mode analysis of single‐storey buildings is explained and its application to industrial halls. Then the robustness in multi‐storey buildings is briefly discussed where the examples of local collapse of beam, column and wind bracing are presented.
Plasma Jet Machining
Authors: Arnold Thomas , Boehm Georg , Eichentopf Inga‐Maria , Janietz Manuela , Meister Johannes , Schindler Axel
Published: August 2010

Plasma Jet Machining (PJM) is a surface figuring technology based on atmospheric plasma assisted chemical etching or deposition, respectively. In both cases a sub‐aperture plasma jet source is used combined with a CNC multi‐axes system for the processing of curved surfaces. It is under development for the surface figuring of a variety of optical materials by IOM for about 15 years. PJM is capable to figure deep aspheric or free‐form substrates with high material removal rate and high spatial resolution. Based on chemical reactions between plasma generated radicals and the surface PJM does not introduce any damage to the processed surface and sub‐surface region in contrast to abrasive techniques. Deterministic deposition of SiOx layers and subsequent proportional transfer using ion beams or polishing is another plasma jet based technique for surface figuring that extends the range of machinable materials. The article gives an overview on the current state of PJM development in IOM and shows examples of its application.
Zugkraft‐Lastenträger für Vakuumisolation
Authors: Schatz Viktor
Published: August 2010

Ein lang gehegter Wunsch vieler Forscher und Entwickler von Abstandhaltern für gestützte Vakuumanordnungen ist wahr geworden und ein einfach herstellbarer elementarer Zugkraft‐Lastenträger entwickelt worden, der es möglich macht, mittels auf Zuglast beanspruchter Kraftübertragungselemente die auf beabstandete Wandungen wirkende Druckdifferenzkräfte zu übertragen. Dadurch sind konduktive Wärmeleitwerte bis zu 1E‐6 W/mK und darunter erreichbar. Die Zugkraft‐Lastenträger erlauben ferner eine einfache Unterbringung unbelasteter Strahlungsschildmittel im evakuierten Hohlraum. Außerdem verfügen diese Zugkraft‐Lastenträger über verbesserte Evakuierbarkeit und weisen große Reserven für konstruktive und stoffliche Anpassungen in Anwendungen auf. Es werden insbesondere wärmebrückenfreie evakuierbare Systemanordnungen realisierbar, aber auch randversiegelte VIP‐Platten profitieren durch erreichbare Leistungssteigerung und Kostensenkung.
Prospects for decadal climate prediction
Authors: Keenlyside Noel S. , Ba Jin
Published: August 2010

During the last decade, global surface temperatures did not increase as rapidly as in the preceding decades. Although relatively small compared to the observed centennial scale global warming, it has renewed interest in understanding and even predicting climate on time scales of decades, and sparked a community initiative on near‐term prediction that will feature in the fifth intergovernmental panel on climate change assessment report. Decadal prediction, however, is in its infancy, with only a few publications existing. This article has three aims. The first is to make the case for decadal prediction. Decadal fluctuations in global climate similar to that of recent decades were observed during the past century. Associated with large regional changes in precipitation and climate extremes, they are of socioeconomic importance. Climate models, which capture some aspects of observed decadal variability, indicate that such variations might be partly predictable. The second aim is to describe the major challenges to skilful decadal climate prediction. One is poor understanding of mechanisms of decadal climate variability, with climate models showing little agreement. Sparse observations in the past, particularly in the ocean, are also a limiting factor to developing and testing of initialization and prediction systems. The third aim is to stress that despite promising initial results, decadal prediction is in a highly experimental stage, and care is needed in interpreting results and utilizing data from such experiments. In the long‐term, decadal prediction has the potential to improve models, reduce uncertainties in climate change projections, and be of socioeconomic benefit. Copyright © 2010 John Wiley & Sons, Ltd.

This article is categorized under:

Climate Models and Modeling > Earth System Models

Climate Models and Modeling > Knowledge Generation with Models
Location‐aided medium access control for low data rate UWB wireless sensor networks
Authors: Karapistoli Eirini , Gragopoulos Ioannis , Tsetsinas Ioannis , Pavlidou Fotini‐Niovi
Published: August 2010

This paper presents a distributed medium access control (MAC) protocol for low data rate ultra‐wideband (UWB) wireless sensor networks (WSNs), named LA‐MAC. Current MAC proposal is closely coupled to the IEEE 802.15.4a physical layer and it is based on its Impulse‐Radio (IR) paradigm. LA‐MAC protocol amplifies its admission control mechanism with location‐awareness, by exploiting the ranging capability of the UWB signals. The above property leads to accurate interference predictions and blocking assessments that each node in the network can perform locally, limiting at the same time the actions needed to be performed towards the admission phase. LA‐MAC is evaluated through extensive simulations, showing a significant improvement in many critical parameters, such as throughput, admission ratio, energy consumption, and delay, under different traffic load conditions. Copyright © 2010 John Wiley & Sons, Ltd.
Characterization of the unsteady flow in the nacelle region of a modern wind turbine
Authors: Zahle Frederik , Sørensen Niels N.
Published: August 2010

A three‐dimensional Navier–Stokes solver has been used to investigate the flow in the nacelle region of a wind turbine where anemometers are typically placed to measure the flow speed and the turbine yaw angle. A 500 kW turbine was modelled with rotor and nacelle geometry in order to capture the complex separated flow in the blade root region of the rotor. A number of steady state and unsteady simulations were carried out for wind speeds ranging from 6 m s−1 to 16 m s−1 as well as two yaw and tilt angles. The flow in the nacelle region was found to be highly unsteady, dominated by unsteady vortex shedding from the cylindrical part of the blades, which interacted with the root vortices from each blade, generating high‐velocity gradients. As a consequence, the nacelle wind speed and the nacelle flow angle were found to vary significantly with the height above the nacelle surface. The nacelle anemometry showed significant dependence on both yaw and tilt angles with yaw errors of up to 10 degrees when operating in a tilted inflow. Copyright © 2010 John Wiley & Sons, Ltd.
Adaptive post‐processing of short‐term wind forecasts for energy applications
Authors: Sweeney C. , Lynch P.
Published: August 2010

We present a new method of reducing the error in predicted wind speed, thus enabling better management of wind energy facilities. A numerical weather prediction model, COSMO, was used to produce 48 h forecast data every day in 2008 at horizontal resolutions of 10 and 3 km. A new adaptive statistical method was applied to the model output to improve the forecast skill. The method applied corrective weights to a set of forecasts generated using several post‐processing methods. The weights were calculated based on the recent skill of the different forecasts. The resulting forecast data were compared with observed data, and skill scores were calculated to allow comparison between different post‐processing methods. The total root mean square error performance of the composite forecast is superior to that of any of the individual methods. Copyright © 2010 John Wiley & Sons, Ltd.
Signaling pathways that control cell migration: models and analysis
Authors: Welf Erik S. , Haugh Jason M.
Published: August 2010

Dissecting the intracellular signaling mechanisms that govern the movement of eukaryotic cells presents a major challenge, not only because of the large number of molecular players involved, but even more so because of the dynamic nature of their regulation by both biochemical and mechanical interactions. Computational modeling and analysis have emerged as useful tools for understanding how the physical properties of cells and their microenvironment are coupled with certain biochemical pathways to actuate and control cell motility. In this focused review, we highlight some of the more recent applications of quantitative modeling and analysis in the field of cell migration. Both in modeling and experiment, it has been prudent to follow a reductionist approach in order to characterize what are arguably the principal modules: spatial polarization of signaling pathways, regulation of the actin cytoskeleton, and dynamics of focal adhesions. While it is important that we ‘cut our teeth’ on these subsystems, focusing on the details of certain aspects while ignoring or coarse‐graining others, it is clear that the challenge ahead will be to characterize the couplings between them in an integrated framework. WIREs Syst Biol Med 2011 3 183–190 DOI: 10.1002/wsbm.110.

This article is categorized under:

Analytical and Computational Methods > Analytical Methods

Models of Systems Properties and Processes > Cellular Models

Biological Mechanisms > Cell Signaling
Diaminouronium Nitriminotetrazolates – Thermally Stable Explosives
Authors: Fischer Niko , Klapötke Thomas M. , Piercey Davin , Scheutzow Susanne , Stierstorfer Jörg
Published: August 2010

Diaminouronium 5‐nitriminotetrazolate (1) and diaminouronium 1‐methyl‐5‐nitrimino‐tetrazolate (2) were synthesized by the reaction of diaminourea with 5‐nitriminotetrazole (3) and 1‐methyl‐5‐nitriminotetrazole (4), respectively. The energetic compounds 1 and 2 were fully characterized by single‐crystal X‐ray diffraction, NMR spectroscopy, IR‐ and Raman spectroscopy as well as DSC measurements. The sensitivities towards impact, friction and electrical discharge were determined. Several detonation parameters (e.g. heat of explosion, detonation velocity) were computed by the EXPLO5 computer code based on calculated (CBS‐4M) heats of formation and X‐ray densities. In addition, the detonation velocity of 1 was experimentally determined and compared to the computed values.
Outcomes of Staple Fixation of Mesh Versus Nonfixation in Laparoscopic Total Extraperitoneal Inguinal Repair: A Meta‐Analysis of Randomized Controlled Trials
Authors: Tam Ka‐Wai , Liang Hung‐Hua , Chai Chiah‐Yang
Published: August 2010

Background

Staple fixation of mesh during laparoscopic total extraperitoneal (TEP) inguinal repair is thought to be necessary to prevent recurrence. However, mesh fixation may increase surgical complications and pain. Therefore, a meta‐analysis of randomized controlled trials (RCTs) was conducted to compare the outcomes of nonfixation with fixation of mesh by metal tacks during TEP inguinal hernia repair.

Methods

The meta‐analysis was conducted according to the Quality of Reporting of Meta‐analyses (QUOROM) standards. The inclusion criteria were RCTs comparing stapled with unstapled mesh in TEP inguinal hernia repair. The primary outcome was incidence of recurrence, secondary outcomes were operative duration, postoperative pain score, number of analgesics consumed, in‐hospital stay, time to return to normal activity, cost, and complications.

Results

Six trials were included with a total number of 932 patients (1086 hernias): the mesh was fixed in 463 (540 hernias) patients and not fixed in 469 (546 hernias). We found no difference between groups in the incidence of recurrence (OR = 2.01, 95% CI: 0.37–11.02), complications (OR = 0.73, 95% CI: 0.51–1.05), postoperative pain score [day 1 (p = 0.19), day 7 (p = 0.18) and month 1 (p = 0.47)] and number of analgesics consumed (WMD of −1.20, 95% CI: −3.08 to 0.68). The mean operative time (WMD of −3.86, 95% CI: −7.45 to −0.26) and hospital stay (WMD of −0.34, 95% CI: −0.50 to −0.18) were significantly higher in the mesh fixation group. Moreover, a net cost savings was realized for each hernia repair performed without stapled mesh.

Conclusions

Elimination of tack fixation of mesh in TEP inguinal hernia repair is associated with decreased operative cost and significantly reduce operative time and in‐hospital stay, but no difference in the risk of hernia recurrence, complications, and postoperative pain. For more detailed evaluation, further well‐structured trials with improved standardization of hernia type, operative technique, and surgeon experience are necessary.
Initial evaluation of a biochemical cystic fibrosis newborn screening by sequential analysis of immunoreactive trypsinogen and pancreatitis‐associated protein (IRT/PAP) as a strategy that does not involve DNA testing in a Northern European population
Authors: Sommerburg Olaf , Lindner Martin , Muckenthaler Martina , Kohlmueller Dirk , Leible Svenja , Feneberg Reinhard , Kulozik Andreas E. , Mall Marcus A. , Hoffmann Georg F.
Published: August 2010

Background

Ethical concerns and disadvantages of newborn screening (NBS) for cystic fibrosis (CF) related to genetic testing have raised controversies and impeded implementation of CF NBS in some countries. In the present study, we used a prospective and sequential immunoreactive trypsinogene (IRT)/pancreatitis‐associated protein (PAP) strategy, with IRT as first and PAP as second tier, and validated this biochemical approach against the widely used IRT/DNA protocol in a population‐based NBS study in southwest Germany.

Methods

Prospective quantitation of PAP and genetic analysis for the presence of four mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene most prevalent in southwest Germany (F508del, R553X, G551D, G542X) were performed in all newborns with IRT > 99.0th percentile. NBS was rated positive when either PAP was ≥1.0 ng/mL and/or at least one CFTR mutation was detected. In addition, IRT > 99.9th percentile was also considered a positive rating. Positive rating led to referral to a CF centre for testing of sweat Cl− concentration.

Findings

Out of 73,759 newborns tested, 98 (0.13%) were positive with IRT/PAP and 56 (0.08%) with IRT/DNA. After sweat testing of 135 CF NBS‐positive infants, 13 were diagnosed with CF. Detection rates were similar for both IRT/PAP and IRT/DNA. One of the 13 diagnosed CF newborns had a PAP concentration <1.0 ng/mL.

Conclusions

Sequential measurement of IRT/PAP provides good sensitivity and specificity and allows reliable and cost‐effective CF NBS which circumvents the necessity of genetic testing with its inherent ethical problems.
MAD SUBALGEBRAS AND LIE SUBALGEBRAS OF AN ENVELOPING ALGEBRA
Authors: TANG XIN
Published: August 2010

Let 𝒰(𝔯(1)) denote the enveloping algebra of the two-dimensional nonabelian Lie algebra 𝔯(1) over a base field 𝕂. We study the maximal abelian ad-nilpotent (mad) associative subalgebras and finite-dimensional Lie subalgebras of 𝒰(𝔯(1)). We first prove that the set of noncentral elements of 𝒰(𝔯(1)) admits the Dixmier partition, 𝒰(𝔯(1))−𝕂=⋃ 5i=1Δi, and establish characterization theorems for elements in Δi, i=1,3,4. Then we determine the elements in Δi, i=1,3 , and describe the eigenvalues for the inner derivation ad Bx,x∈Δi, i=3,4 . We also derive other useful results for elements in Δi, i=2,3,4,5 . As an application, we find all framed mad subalgebras of 𝒰(𝔯(1)) and determine all finite-dimensional nonabelian Lie algebras that can be realized as Lie subalgebras of 𝒰(𝔯(1)) . We also study the realizations of the Lie algebra 𝔯(1) in 𝒰(𝔯(1)) in detail.
The Bishop's Two Bodies: Ambrose and the Basilicas of Milan
Authors: Chin Catherine M.
Published: August 2010

The late ancient body is a historiographical problem. In the combined lights of feminist, Foucaultian, and post-Foucaultian methodologies, much recent scholarship on bodies in late antiquity has focused on bodies as sites on which power relations are enacted and as discourses through which ideologies are materialized. Contemporary concern with definitions and representations of the posthuman, however—for example, in medical technologies that expand the capacities of particular human bodies, in speculative pursuit of the limits of avatars, or in the technological pursuit of artificial intelligence or artificial life—seem both to underline the fundamental lability of the body, and to require a broadening of scholarly focus beyond the traditional visible boundaries of the human organism. At the same time, scholarship on the posthuman emphasizes contemporaneity and futurity to an extent that may seem to preclude engagement with the premodern. I would like to suggest here that doubt about the boundaries of human embodiment is a useful lens through which to reconsider some very traditional questions in the history of Christianity, and that we may begin to think of bodies in Christian premodernity in terms of what we might call their pre-humanity, that is, as fundamentally open to extension, transformation, and multiple instantiation. The figure on whom I focus is Ambrose, the fourth-century bishop of Milan, who, I argue, defined his own body in such a way that he was able to instantiate physically in dozens of living human bodies, at least two dead human bodies, thousands of angelic bodies, and four church buildings. Ambrose's dynamic conception of his episcopal body was formed within a complex political and theological situation, so questions concerning the political ideology of bodies remain very much at issue. I add to these questions a concern for premodern uncertainty about how to recognize a body, both when it is visible and, perhaps more importantly, when it is not.
Dutch Contributions to Religious Toleration
Authors: Bangs Jeremy Dupertuis
Published: August 2010

Historians have neglected a seventeenth-century hero whose actions and words laid the groundwork for America's democratic diversity and religious toleration—at least that is the theme of a best-selling history of the Dutch colony of New Netherland, the predecessor of New York. This courageous but forgotten lawyer, Adriaen van der Donck, went out from Holland in 1641 as a young man to serve as “schout” (chief judicial officer, both sheriff and prosecutor) of Rensselaerwyck, then moved to New Amsterdam where he eventually became the spokesman of colonists irked by the arbitrary highhandedness of the Director General, Petrus Stuyvesant. Van der Donck is now proclaimed to have ensured that Dutch religious toleration became the basic assumption and pattern that evolved into modern American religious pluralism. The great popularity of this recent revelation ensures that thousands of people, from general readers to professional historians whose specialty lies elsewhere, now believe that religious toleration in America originated in New Amsterdam/ New York, where Dutch customs of toleration contrasted with the theocratic tendencies of English colonies. Is this claim true? In my opinion—no. Should historians pay attention to journalistic jingoism? Perhaps—because unexamined assumptions affect topics treated more seriously. What, then, can be said about the fabled Dutch tradition of toleration and its contribution to the discussion of religious freedom in America in the seventeenth and eighteenth centuries?
Horace Bushnell among the Metaphysicians
Authors: Albanese Catherine L.
Published: August 2010

On December 15, 1851, Andrew Jackson Davis—self-styled Harmonial philosopher and noted scion of the spiritualist world—sent a public letter. Addressed through theHartford Timesto the controversial Congregationalist minister Horace Bushnell, the message concerned the first of a series of lectures Bushnell was delivering at his North Church. Davis, who at the time claimed Hartford, Connecticut, as his base, was clearly excited. The announced topic—“On the Naturalistic Theories of Religion as Opposed to Supernatural Revelation”—already gave Davis “much pleasure,” suggesting a position “entirelyunlikeany other ever assumed by the clergy of Christendom.” More than that, Bushnell's way of approaching the subject and defining his position was “considerably unlike the method pursued by most clergymen,” since Bushnell relied on his own “reasonor judgment” to address “thecorrespondingfaculty in the mind of the hearer.” Davis went on to propose that, with so important an issue, better to move the lectures from Bushnell's North Church pulpit to a different location and to invite “all parties interested” to “analyze and examinebefore the same audiencethe various positions.”
Corrigendum: amenability of ultrapowers of Banach algebras
Authors: Daws Matthew
Published: August 2010

Some of the results of § 5 of the cited paper are incorrect: in particular, the characterization of when an algebra is ultra-amenable, in terms of a diagonal like construction, is not proved; and Theorem 5.7 is stated wrongly. The rest of the paper is unaffected. We shall show in this corrigendum that Theorem 5.7 can be corrected and that the other results of § 5 are true if the algebra in question has a certain approximation property.