bluuebunny/crossref_metadata_2025 huggingface dataset:
Quo vadis? Vererbung von Peroxisomen bei der Zellteilung
Authors: Hille‐Rehfeld Annette
Published: November 2005

Bei der Zellteilung von Eukaryoten müssen die Kompartimente gleichmäßig auf die Tochterzellen verteilt werden. Die Vererbung von Peroxisomen wird dabei durch die Balance ihrer Wanderung entlang von Actinfilamenten und ihrer Verankerung am peripheren Cytoskelett reguliert.
Randomized clinical trial comparing lightweight composite mesh with polyester or polypropylene mesh for incisional hernia repair
Authors: Conze J , Kingsnorth A N , Flament J B , Simmermacher R , Arlt G , Langer C , Schippers E , Hartley M , Schumpelick V
Published: November 2005

Background

Polymer mesh has been used to repair incisional hernias with lower recurrence rates than suture repair. A new generation of mesh has been developed with reduced polypropylene mass and increased pore size. The aim of this study was to compare standard mesh with new lightweight mesh in patients undergoing incisional hernia repair.

Methods

Patients were randomized to receive lightweight composite mesh, or standard polyester or polypropylene mesh. Outcomes were evaluated at 21 days, 4, 12 and 24 months from patient responses to the Short Form 36 (SF-36) and daily activity questionnaires. Complications and recurrence rates were recorded.

Results

A total of 165 patients were included in an intention-to-treat analysis (83 lightweight mesh, 82 standard mesh). Postoperative complication rates were similar. The overall hernia recurrence rate was 17 per cent with the lightweight mesh versus 7 per cent with the standard mesh (P = 0·052). There were no differences in SF-36 physical function scores or daily activities between 21 days and 24 months after surgery.

Conclusion

The use of the lightweight composite mesh for incisional hernia repair had similar outcomes to polypropylene or polyester mesh with the exception of a non-significant trend towards increased hernia recurrence. The latter may be related to technical factors with regard to the specific placement and fixation requirements of lightweight composite mesh.
Randomized clinical trial comparing blue dye with combined dye and isotope for sentinel lymph node biopsy in breast cancer
Authors: Hung W K , Chan C M , Ying M , Chong S F , Mak K L , Yip A W C
Published: November 2005

Background

Use of blue dye alone as a marker for sentinel lymph node (SLN) biopsy is effective, but combining it with isotope marking can improve the success rate. Use of the isotope adds extra cost and there are potential radiation hazards. The two techniques were compared in a randomized trial.

Methods

Women with early breast cancer (less than 3 cm) and no palpable axillary nodes were recruited. Women older than 70 years with multicentric cancers or previous surgery to the breast or axilla were excluded. Patients were randomized to either blue dye alone or combined mapping for SLN biopsy. All women had a level I and II axillary dissection after the SLN biopsy.

Results

A total of 123 patients were recruited, of whom five were excluded from analysis. Blue dye alone was used in 57 women and 61 had combined mapping. Baseline demographic data were similar in the two cohorts. The success rate of SLN biopsy was higher with combined mapping than with blue dye alone (100 versus 86 per cent; P = 0·002). The accuracy and false-negative rate were similar (accuracy 100 per cent for combined mapping versus 98 per cent for blue dye; false-negative rate 0 versus 5 per cent).

Conclusion

Combined mapping was superior to blue dye alone in identification of the SLN, but accuracy and false-negative rates were similar.
Blood vessel stem cells and wound healing
Authors: Watt S M , Fox A
Published: November 2005

This article continues the Journal's ‘Scientific Surgery’ series of leaders. The aim of the series, published throughout 2005, has been to highlight areas of bioscience that, while still largely confined to the experimental laboratory, may soon be brought into the clinical domain. In this month's paper Watt and Fox offer an up to date insight into the processes of tissue healing and suggest possible future therapeutic strategies.
Proteomics and clinical surgery
Authors: Roblick U J , Auer G
Published: November 2005

This article concludes the Journal's ‘Scientific Surgery’ series of leaders. The series, published throughout 2005, has highlighted areas of bioscience that may soon be transferred from the laboratory into the clinical sphere. In this final paper Roblick and Auer consider the future role of the surgeon in the era of the ‘diagnostic chip’.
Replacement of Isobutyl by Trifluoromethyl in Pepstatin A Selectively Affects Inhibition of Aspartic Proteinases
Authors: Binkert Christoph , Frigerio Massimo , Jones Andrew , Meyer Solange , Pesenti Cristina , Prade Lars , Viani Fiorenza , Zanda Matteo
Published: November 2005

Two bis‐trifluoromethyl pepstatin A analogues, carboxylic acid 1 and its methyl ester 2, have been synthesised in order to probe the properties and size of the trifluoromethyl (Tfm) group and compare it to the “bigger” isobutyl that is present in pepstatin A. The results demonstrate that Tfm can effectively replace the isobutyl chain as far as inhibitory activity against plasmepsin II (PM II), an aspartic proteinase from Plasmodium falciparum, is concerned. On the other hand, replacement of isobutyl by Tfm selectively affected activity against other aspartic proteinases tested. Two lines of evidence led to these conclusions. Firstly, compounds 1 and 2 retained single‐digit nanomolar inhibitory activity against PM II, but were markedly less active against PM IV, cathepsin D and cathepsin E. Secondly, the X‐ray crystal structures of the three complexes of PM II with 1, 2 and pepstatin A were obtained at 2.8, 2.4 and 1.7 Å resolution, respectively. High overall similarity among the three complexes indicated that the central Tfm was well accommodated in the lipophilic S1 pocket of PM II, where it was involved in tight hydrophobic contacts. The interaction of PM II with Phe111 appeared to be crucial. Comparison of the crystal structures presented here, with X‐ray structures or structural models of PM IV and cathepsin D, allowed an interpretation of the inhibition profiles of pepstatin A and its Tfm variants against these three enzymes. Interactions of the P1 side chain with amino acids that point into the S1 pocket appear to be critical for inhibitory activity. In summary, Tfm can be used to replace an isobutyl group and can affect the selectivity profile of a compound. These findings have implications for the design of novel bioactive molecules and synthetic mimics of natural compounds.
Regioselective Carbon–Carbon Bond Formation in Proteins with Palladium Catalysis; New Protein Chemistry by Organometallic Chemistry
Authors: Kodama Koichiro , Fukuzawa Seketsu , Nakayama Hiroshi , Kigawa Takanori , Sakamoto Kensaku , Yabuki Takashi , Matsuda Natsuko , Shirouzu Mikako , Takio Koji , Tachibana Kazuo , Yokoyama Shigeyuki
Published: November 2005

Palladium‐catalyzed reactions have contributed to the advancement of many areas of organic chemistry, in particular, the synthesis of organic compounds such as natural products and polymeric materials. In this study, we have used a Mizoroki–Heck reaction for site‐specific carbon–carbon bond formation in the Ras protein. This was performed by the following two steps: 1) the His6‐fused Ras protein containing 4‐iodo‐L‐phenylalanine at position 32 (iF32‐Ras‐His) was prepared by genetic engineering and 2) the aryl iodide group on the iF32‐Ras‐His was coupled with vinylated biotin in the presence of a palladium catalyst. The biotinylation was confirmed by Western blotting and liquid chromatography–mass spectrometry (LC‐MS). The regioselectivity of the Mizoroki–Heck reaction was furthermore confirmed by LC‐MS/MS analysis. However, in addition to the biotinylated product (bF32‐Ras‐His), a dehalogenated product (F32‐Ras‐His) was detected by LC‐MS/MS. This dehalogenation resulted from the undesired termination of the Mizoroki–Heck reaction due to steric and electrostatic hindrance around residue 32. The biotinylated Ras showed binding activity for the Ras‐binding domain as its downstream target, Raf‐1, with no sign of decomposition. This study is the first report of an application of organometallic chemistry in protein chemistry.
A Medicinal‐Chemistry‐Guided Approach to Selective and Druglike Sigma 1 Ligands
Authors: Corbera Jordi , Vaño David , Martínez Daniel , Vela José M. , Zamanillo Daniel , Dordal Alberto , Andreu Francesc , Hernandez Enric , Perez Raquel , Escriche Marisol , Salgado Leonardo , Yeste Sandra , Serafini Maria Teresa , Pascual Rosalia , Alegre Júlia , Calvet Maria Carme , Cano Núria , Carro Mónica , Buschmann Helmut , Holenz Jörg
Published: November 2005

Based on a medicinal‐chemistry‐guided approach, three novel series of druglike cycloalkyl‐annelated pyrazoles were synthesized and display high affinity (pKi >8) for the σ1 receptor. Structure–affinity relationships were established, and the different scaffolds were optimized with respect to σ1 binding and selectivity versus the σ2 receptor and the hERG channel, resulting in selective compounds that have Kivalues (for σ1) in the subnanomolar range. Selected compounds were screened for cytochrome P450 inhibition (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4), metabolic stability (rat and human liver microsomes), and cell‐membrane permeability (Caco‐2). They showed favorable in vitro ADME properties as well as favorable calculated druglike and experimental physicochemical properties. Furthermore, compounds7 fand17 a, for example, displayed high selectivity (affinity) for the σ1 receptor against a wide range of other receptors (>60). With these valuable tool compounds in hand, we are further exploring the role of the σ1 receptor in relevant animal models corresponding to such medicinal indications as drug abuse, pain, depression, anxiety, and psychosis.
Magnetic enhancement in wildfire‐affected soil and its potential for sediment‐source ascription
Authors: Blake W. H. , Wallbrink P. J. , Doerr S. H. , Shakesby R. A. , Humphreys G. S.
Published: November 2005

Intense rainfall following wildfire can cause substantial soil and sediment redistribution. With concern for the increasing magnitude and frequency of wildfire events, research needs to focus on hydrogeomorphological impacts of fire, particularly downstream fluxes of sediment and nutrients. Here, we investigate variation in magnetic enhancement of soil by fire in burnt eucalypt forest slopes to explore its potential as a post‐fire sediment tracer. Low‐frequency magnetic susceptibility values (χlf) of <10 µm material sourced from burnt slopes (c. 8·0–10·4 × 10−6 m3 kg−1) are an order of magnitude greater than those of <10 µm material derived from long‐unburnt areas (0·8 × 10−6 m3 kg−1). Susceptibility of anhysteretic remanent magnetization (χARM) and saturation isothermal remanent magnetization (SIRM) values are similarly enhanced. Signatures are strongly influenced by soil and sediment particle size and storage of previously burnt material in footslope areas. Whilst observations indicate that signatures based on magnetic enhancement show promise for post‐fire sediment tracing, problems arise with the lack of dimensionality in such data. Magnetic grain size indicators χfd%, χARM/SIRM and χfd/χARM offer further discrimination of source material but cannot be included in numerical unmixing models owing to non‐linear additivity. This leads to complications in quantitatively ascribing downstream sediment to source areas of contrasting burn severity since sources represent numerical multiples of each other, indicating the need to involve additional indicators, such as geochemical evidence, to allow a more robust discrimination. Copyright © 2005 John Wiley & Sons, Ltd.
Assessing soil erosion rates in cultivated areas of Navarre (Spain)
Authors: De Santisteban L. M. , Casalí J. , López J. J.
Published: November 2005

Although there is much evidence of intense soil erosion in cultivated areas of Navarre (Spain), information on it is currently scarce. Rill and ephemeral gully volumes can be used as a guide to minimum erosion rates. With the main purpose of determining the annual soil loss rates in cultivated areas of central Navarre, a detailed assessment of rainfall and of rill and gully erosion was made in 19 small catchments from October 1999 to September 2001. Seventeen of them were randomly selected, and were cultivated with winter cereals, vineyards or sunflowers. The other two catchments were selected to represent partially uncultivated lands abandoned for ten years. Channel cross‐sections were measured by using a 1‐m‐wide micro‐topographic profile meter, describing 632 cross‐sections and processing information from 31 600 pins. Erosive events happened every year in the three study areas. For cereal catchments, soil losses occurred in only one or two rainfall events each year, usually at the end of autumn and in some summers, with high erosion rates (0·20–11·50 kg m−2 a−1). In vineyards, soil losses occurred several times per year, and in any season. This is attributed to the small percentage of surface covered by the crop throughout the year. Again, high erosion rates were found (0·33–16·19 kg m−2 a−1), with ephemeral gully erosion causing more loss than rill erosion. No‐till is proposed as an effective conservation measure. From this large data set, it can be stated that rill erosion and ephemeral gully erosion are widespread in Mediterranean regions, and that much more attention should be paid to the problem. Abandoned fields showed very high erosion rates (16·19 kg m−2 a−1 on average), suggesting that the abandonment of marginal lands without implementing any erosion control can lead to severe erosion rates. Copyright © 2005 John Wiley & Sons, Ltd.
Channel head location and characteristics using digital elevation models
Authors: Hancock G. R. , Evans K. G.
Published: November 2005

The drainage network is the conduit through which much surface water and sediment are routed within a catchment. In a catchment, the position of where hillslopes begin and channels end has long been considered the position of transition between diffusive processes upslope and the more incisive fluvial processes downslope. Consequently, understanding channel head location is an important issue in understanding catchment hydrology and geomorphology. This study examines channel head position and characteristics in a catchment in Arnhem Land, Northern Territory, Australia. In this study the position of channel heads was mapped within the catchment and plotted on a reliable digital elevation model of the catchment. It was found that the majority of channel heads have relatively small source areas and that graphical catchment descriptors, such as the area–slope relationship and cumulative area distribution, can provide reliable measures of the field position of the heads of first‐order streams and the transition from hillslope to channel. The area–slope relationship and cumulative area distribution are also shown to be good tools for determining digital elevation model grid size which can capture hillslope detail and the transition from hillslope to channel. Copyright © 2005 John Wiley & Sons, Ltd.
Rotor resistance tuning for indirect stator flux orientated induction motor drive based on MRAS scheme
Authors: Koubaa Yassine , Boussak Mohamed
Published: November 2005

In this paper, the indirect stator flux orientated controlled (ISFOC) induction motor drive is presented. In order to eliminate the effect of parameter variation on the ISFOC induction motor drive, an adaptation algorithm for tuning the rotor resistance is proposed. Based on the model reference adaptive system (MRAS) scheme, the rotor resistance is tuned to obtain an exact ISFOC induction motor drive. The integral plus proportional (IP) speed controller is designed using a model‐based analytical method in order to obtain a speed step response without overshoot. The reference and adjustable models, developed in the stationary stator reference frame, are used in the MRAS scheme to estimate induction rotor resistance from measured terminal voltages and currents. The major contributions of this work are: first, taking into account the variations of the rotor resistance during start‐up and normal operations; and second, the IP gains speed controller and PI gains current controller are calculated and tuned at each sampling time according to the new estimated rotor resistance. Computer simulation results show the satisfactory behaviour of the proposed identification method. Copyright © 2005 John Wiley & Sons, Ltd.
Soft magnetic materials for electrical engineering: state of the art and recent advances
Authors: Alves F. , Lebourgeois R. , Waeckerlé T.
Published: November 2005

This article gives a brief description of the essential characteristics and principal applications of amorphous, crystalline and nanostructured soft magnetic materials in electrical engineering. Copyright © 2005 John Wiley & Sons, Ltd.
Implementation of a dual vector control strategy in a doubly‐fed machine drive
Authors: Azaza Henda , Masmoudi Ahmed
Published: November 2005

The paper deals with the control of a variable speed drive made up of a doubly‐fed motor (DFM) and a rotor converter including two current‐regulated voltage inverters connected through a DC link: the rotor‐side inverter and the line‐side one. Two vector control strategies are implemented using electrical variables expressed in the frame held by the DFM stator flux. High transient and steady‐state performances of the DFM have been gained, thanks to the implementation of the stator‐flux‐oriented control in the rotor‐side inverter even though the flux loop lacks accuracy, while a unity overall power factor operation has been achieved with the implementation of a (P,Q) vector control strategy in the line‐side inverter. Copyright © 2005 John Wiley & Sons, Ltd.
Design and comparison of different flux‐switch synchronous machines for an aircraft oil breather application
Authors: Amara Yacine , Hoang Emmanuel , Gabsi Mohamed , Lécrivain Michel , Allano Sylvain
Published: November 2005

This paper presents a design procedure of a flux–switch synchronous machine for an aircraft oil breather application. This work is part of a European project called ‘Power Optimised Aircraft’. The aim of this project is to replace some mechanical equipment by electromechanical devices to improve performance and reduce power consumption. The structure under study was developed at SATIE laboratory and it is based on the flux‐switch principle. The permanent magnets are located in the stator, and the rotor is entirely passive. The study described in this paper is limited to the electromagnetic design. Copyright © 2005 John Wiley & Sons, Ltd.
On the reduction of the commutation frequency in DTC: a comparative study
Authors: Ben Salem F. , Yangui A. , Masmoudi A.
Published: November 2005

The paper deals with a comparison between three DTC strategies: (i) the original one introduced by Takahashi which is based on an empirical approach, (ii) a strategy based on an analytical approach which takes into account the torque dynamic considering four quadrant operation, and (iii) an extension of the second approach considering twelve ‘active’ voltage space vectors. It has been found that a reduction of the commutation frequency has been gained going from the first strategy to the third one. This opens up crucial efficiency benefits, as far as the commutation losses in the inverter are considerably reduced. Copyright © 2005 John Wiley & Sons, Ltd.
Numerical convergence of the MPFA O‐method and U‐method for general quadrilateral grids
Authors: Aavatsmark I. , Eigestad G. T.
Published: November 2005

Control‐volume discretization methods are applicable for problems that require good numerical approximations of fluxes. Here, a class of flux‐continuous discretization methods, denoted multipoint flux approximation methods (MPFA), is discussed, and two different approaches are derived. The resulting discrete equations use pressures as the only unknowns, and the fluxes will be given explicitly as weighted sums of the discrete pressures. The two methods are denoted the O‐method and the U‐method, respectively, and differ in the way that continuity requirements are embedded in the discrete equations. Numerical tests are provided for smooth problems and problems with discontinuous coefficients for both the O‐method and the U‐method. Convergence rates of the methods are indicated through numerical experiments on smooth and rough grids. Copyright © 2005 John Wiley & Sons, Ltd.
Numerical boundary conditions for globally mass conservative methods to solve the shallow‐water equations and applied to river flow
Authors: Burguete J. , García‐Navarro P. , Murillo J.
Published: November 2005

A revision of some well‐known discretization techniques for the numerical boundary conditions in 1D shallow‐water flow models is presented. More recent options are also considered in the search for a fully conservative technique that is able to preserve the good properties of a conservative scheme used for the interior points. Two conservative numerical schemes are used as representatives of the families of explicit and implicit numerical methods. The implementation of the different boundary options to these schemes is compared by means of the simulation of several test cases with exact solution. The schemes with the global conservation boundary discretization are applied to the simulation of a real river flood wave leading to very satisfactory results. Copyright © 2005 John Wiley & Sons, Ltd.
Boundary element solution of unsteady magnetohydrodynamic duct flow with differential quadrature time integration scheme
Authors: Bozkaya C. , Tezer‐Sezgin M.
Published: November 2005

A numerical scheme which is a combination of the dual reciprocity boundary element method (DRBEM) and the differential quadrature method (DQM), is proposed for the solution of unsteady magnetohydrodynamic (MHD) flow problem in a rectangular duct with insulating walls. The coupled MHD equations in velocity and induced magnetic field are transformed first into the decoupled time‐dependent convection–diffusion‐type equations. These equations are solved by using DRBEM which treats the time and the space derivatives as nonhomogeneity and then by using DQM for the resulting system of initial value problems. The resulting linear system of equations is overdetermined due to the imposition of both boundary and initial conditions. Employing the least square method to this system the solution is obtained directly at any time level without the need of step‐by‐step computation with respect to time. Computations have been carried out for moderate values of Hartmann number (M⩽50) at transient and the steady‐state levels. As M increases boundary layers are formed for both the velocity and the induced magnetic field and the velocity becomes uniform at the centre of the duct. Also, the higher the value of M is the smaller the value of time for reaching steady‐state solution. Copyright © 2005 John Wiley & Sons, Ltd.
Recent increase in persistence of atmospheric circulation over Europe: comparison with long‐term variations since 1881
Authors: Kyselý Jan , Domonkos Peter
Published: November 2005

Long‐term changes in the persistence of atmospheric circulation (measured by the mean residence time of circulation types) over Europe since 1881 are studied using the Hess–Brezowsky classification of Grosswetterlagen. A comprehensive statistical analysis is performed utilizing tests for change points, trends and outliers. The most remarkable feature of the long‐term variations in the persistence of circulation patterns is a general sharp increase from the 1970s to the late 1980s. The shift towards higher persistence is statistically significant in most groups of the types and most seasons and is confirmed by all the statistical tools. The 1986–2000 period is an outlier, and the most pronounced change point in the time series appears in the mid‐1980s. The observed increase in the mean lifetime of the circulation types over European mid‐latitudes seems to be consistent with the idea of global warming, which is likely to shift the areas with the highest baroclinic activity (storm tracks) northwards. The enhanced persistence of the atmospheric circulation may have also supported the more frequent occurrence of temperature and other climatic extremes in Europe recently. Copyright © 2005 Royal Meteorological Society.
Study of the effect of ripening stages and climatic conditions on the physicochemical and sensorial parameters of two varieties of Vitis vinifera L. by principal component analysis: influence on enzymatic browning
Authors: Serrano‐Megías M , Núñez‐Delicado E , Pérez‐López AJ , López‐Nicolás JM
Published: November 2005

The present paper describes the effects of maturation on the physicochemical, biochemical and color components of Napoleon and Dominga grape varieties, and on any differences between them. Climatic conditions were taken into account to explain the results obtained. Protein levels increased during ripening and were correlated with pH. Polyphenoloxidase activity was affected by climatic conditions (rainfall) and increased to a greater degree in Dominga than in Napoleon. Taste tests were conducted to determine the contribution of physicochemical and biochemical parameters to the sensorial properties of the grapes. Principal components analysis showed that parameters were correlated in different ways during the ripening period in Napoleon and Dominga varieties. In Dominga AE were correlated to the b parameter and in Napoleon to the L parameter. Copyright © 2005 Society of Chemical Industry
Impact of grazing on soil biota in a Mediterranean grassland
Authors: Li Q. , Mayzlish E. , Shamir I. , Pen‐Mouratov S. , Sternberg M. , Steinberger Y.
Published: November 2005

The effect of cattle grazing on the soil nematode and protozoan communities, and on microbial biomass, was measured in Israel's northern highlands. Three grazing areas were compared: (1) with 1·1 cow ha−1 y−1; (2) 0·55 cow ha−1 y−1; and (3) control—no grazing for almost 18 years.

Soil samples were collected from the upper 10 cm level of each area (n = 24), in autumn, before the onset of the rainy season, in order to analyse soil moisture, organic matter, total nitrogen, microbial biomass, soil respiration, soil free‐living nematodes, as well as ciliate and flagellate populations.

Soil microbial biomass and soil free‐living nematodes showed no clear differences in impact between heavy and moderate grazing. However, ciliates and flagellates showed a significant response to different grazing pressures. Copyright © 2005 John Wiley & Sons, Ltd.
Crop and soil variability on terraces in the highlands of SW Uganda
Authors: Siriri D. , Tenywa M. M. , Raussen T. , Zake J. K.
Published: November 2005

Terrace benches on the hillslopes of Western Uganda exhibit a crop‐yield gradient: upper portions of terraces produce less than the lower sections. We investigated the soil factors responsible for this yield variation on 30 terraces along 5 toposequences in what was predominantly a Ferralsol. Two levels of spatial analysis were conducted: (1) variation within individual terraces; and (2) differences across hill‐slope positions. A greenhouse experiment further examined this fertility gradient using soils extracted from the upper, middle and lower parts of the terrace. This included a nitrogen (N) treatment of 70 mg N kg−1 soil. In the fields sorghum (Sorghum bicolor) grain yield differed significantly (p ≤ 0·05) across terraces, increasing from 0·4 Mg ha−1 on the upper 40 per cent of terrace to 2·5 Mg ha−1 on the lower 40 per cent. Soil bulk density decreased down the terraces from 1·41 g cm−3 to 1·18 g cm−3, causing an increase of hydraulic conductivity from 1·6 cm h−1 to 7·3 cm h−1, from the upper to the lower part, respectively. Organic carbon (C) and total N increased from upper to lower terrace sections. In the greenhouse, sorghum growing on soils from which the soil physical limitations have been removed did not show significant yield differences across a terrace as observed in the field. Response to N was most pronounced on the upper terrace sections, increasing sorghum dry matter from 3 g pot−1 to 15 g pot−1. On the lower terrace, N amendment increased dry matter from 4 g pot−1 to 11 g pot−1. Technologies to improve the adverse soil physical conditions and the N limitations on upper terrace parts while preventing tillage‐ and soil‐erosion‐induced terrace scouring are required. Copyright © 2005 John Wiley & Sons, Ltd.
Soil erosion and the adaptive cycle metaphor
Authors: Dorren L. K. A. , Imeson A. C.
Published: November 2005

The landscapes that we live in and the changes that they undergo play an important part in the qualities of our lives. They provide natural goods and services of value to us because of the existence of soil, which is a medium between the solid earth and the sphere in which we live our daily life. The medium soil is constantly subject to change and one of the causes is soil erosion. If one tries to understand or to deal with soil erosion it is helpful to consider soil as an integral part of continuously changing landscapes and to be aware of the different functions of a soil in its environmental context at different scales. To clarify this, we present three important concepts. These are: (1) scale/connectivity; (2) change; and (3) resilience. These concepts will be put in an innovative framework called the panarchy theory, which represents a hierarchical structure in which both human and natural systems are linked together in adaptive cycles. Presenting soil erosion in such a framework allows us to link causes and their impacts at different scales. The application of such a framework and the insight obtained could facilitate the assessment of risks and possibilities for sustainable use. Copyright © 2005 John Wiley & Sons, Ltd.
Concise review of interrill erosion studies in SE Spain (Alicante and Murcia): erosion rates and progress of knowledge from the 1980s
Authors: Boix‐Fayos C. , Martínez‐Mena M. , Calvo‐Cases A. , Castillo V. , Albaladejo J.
Published: November 2005

From the 1980s onward studies on interrill soil erosion were intensified in SE Spain. The main achievements of the research carried out in the field areas of Alicante and Murcia concern: first, (1) the estimation of erosion rates directly in the field under a wide range of methodologies, different scales and different environmental conditions; (2) estimations based on existing models, such as the USLE, carried out for different subcatchments of the Segura and Júcar catchments; and (3) other parametric and physical event‐based models have also been calibrated and validated.

Second, the progress of the knowledge in understanding erosion mechanisms. New and reviewed concepts regarding mainly hydrological behaviour and sediment movement and transport at patch, slope and catchment scale have improved our understanding of soil‐erosion processes in Mediterranean‐type ecosystems. These concepts focus on: (1) the definition of runoff generation models more appropriate to Mediterranean conditions; (2) the definition of thresholds for runoff generation; (3) the definition of models of soil water redistribution within soils and at landscape level; (4) the establishment of conditions and controls for sediment detachment and movement; and (5) the characterization of the change in the controlling factors of soil erosion and degradation under different environmental characteristics (climatic or human‐induced). The insights into soil‐erosion processes obtained and the renewed hydrological and geomorphological concepts achieved can be very valuable for the design of new strategies of erosion management and ecosystems restoration. Copyright © 2005 John Wiley & Sons, Ltd.
The effectiveness of agro‐environmental schemes in reducing erosion
Authors: Arnoldussen A. H.
Published: November 2005

Autumn and winter in Norway are the most vulnerable periods for erosion. The government aims to reduce the autumn tillage acreage and keep the soil covered by vegetation as much as possible during the winter period. The farmers get support to plough their land in spring; the level of this support is related to the erosion risk. Also, support is given to several technical measures aimed at preventing eroded material reaching streams and rivers. The Agricultural Environmental Scheme has been successful and Norway has reduced nutrient runoff by nearly 50 per cent as required by the North Sea Agreement. However, more can be achieved. From January 2004 the counties and municipalities can further adapt the Agricultural Environmental Scheme to suit the protection of local watersheds. Copyright © 2005 John Wiley & Sons, Ltd.
Dealing with soil threats in Lower Saxony, Germany
Authors: Gunreben M.
Published: November 2005

In Germany a legal federal framework for soil protection was created in 1998 through the Federal Soil Protection Law. A State Soil Protection Law for Lower Saxony was enacted in 1999 in order to regulate the legal aspects of soil protection in Lower Saxony.

The data contained in the soil information system for Lower Saxony (NIBIS®) provide a basis for decision making in state and regional development planning. The NIBIS® plays a significant role as part of the legal framework in respect of soil protection, nature protection and water protection.

The main focus of currently existing state and federal acts on soil conservation is on material impacts (heavy metals, organics) rather than non‐material ones. In consideration of this situation and on behalf of Lower Saxony's Department for Environment, the Lower State Agency for Ecology in cooperation with other state agencies responsible for soil protection, is developing a concept to define targets for soil quality in Lower Saxony.

Standards and aims of soil quality with regard to the factors of erosion and sealing by construction are described. In the case of water erosion, the concept defines degrees of threat to soil fertility depending on the depth of common rooting. For wind erosion, the concept of ‘tolerable field length’ has been introduced. For soil sealing the measure of building coverage with the main components ‘coverage ratio’ and the ‘floor space ratio’ is of great relevance. Consequently, quality standards have been attributed to both components. Copyright © 2005 John Wiley & Sons, Ltd.
The institutional framework of land‐use decisions
Authors: Bizer K.
Published: November 2005

Effective soil‐protection policies should be based on a sound understanding of individual land‐use decisions in order to change it towards more sustainable decisions. This paper argues for the modification of the behavioural model of ‘Homo economicus’ by explicitly allowing for cognitive limits and non‐reflective modes of behaviour in addition to situational utility‐maximizing behaviour. These modifications take into account actual difficulties in changing individual land‐use decisions. While it is possible to adjust behaviour by moral persuasion, consensus‐oriented round‐tables or planning processes, such approaches are unlikely to bring about effective changes in land‐use decisions without changing relative prices. This paper suggests ways to implement a special land‐use tax as a reform model for existing property taxes. Such a land‐use tax applies different rates according to ecological damage. Accordingly, surfaces covered by buildings will pay higher tax rates than free space. Conventional agriculture will pay more than forest areas, and nature reserve areas will be free of charge. Such a land‐use tax, designed as a revenue‐neutral alternative to Germany's property tax, could trigger modest changes in land‐use behaviour in the near future. A general reform of local fiscal relations could increase this effect in the long run. Copyright © 2005 John Wiley & Sons, Ltd.
On the Theory of Micellization Kinetics
Authors: Nyrkova Irina A. , Semenov Alexander N.
Published: November 2005

Summary: We consider certain general features of aggre‐ gation (micellization) processes in solutions of amphiphilic molecules, in particular, block‐copolymers. We demonstrate that non‐equilibrium effects can be very important for micellization. In particular, we show that micelle formation at the conventional (equilibrium) critical micelle concentration (CMC, $c_c$) can be inhibited by high activation energy barriers. This is likely to be the case when the micelles are large. In this case an aggregation actually occurs at higher concentrations, above an apparent CMC, $c_{\rm a}$. The concentration $c_{\rm a}$ can be much higher than the equilibrium CMC. Hence significant hysteresis effects are inherent in amphiphilic systems since micelle formation and dissociation are activation processes. To further clarify this idea we consider relaxation of a micellar system after a temperature jump (or a jump of another essential parameter) and discuss qualitatively different relaxation times corresponding to the relaxations of the micellar sizes and of the total number of micelles. We also discuss different kinetic pathways of micelle formation and relaxation and show that in certain cases the ideal‐gas (combinatorial) contribution to the micelle free energy is significant for the kinetics.

Micelle association and dissociation times vs. reduced concentration.

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Micelle association and dissociation times vs. reduced concentration.
Breaking Water Waves: Unsteady 2D Free‐Surface Computations
Authors: Cooker Mark J.
Published: November 2005

Some numerical methods for the full Euler equations in two space dimensions are reviewed. Efficient computations can be carried out using a boundary‐integral method described, (originally due to J. W. Dold and D. H. Peregrine) which is able to track the unsteady evolution of the free surface of overturning waves. The method is fifth‐order in time and tenth order in space. It has been used to compute violent water motions when a wave collides with a vertical wall, for which high accelerations and large pressure gradients are found. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Lepskij–type Stopping‐Rule for Newton‐type Methods with Random Noise
Authors: Bauer Frank , Hohage Thorsten
Published: November 2005

Regularized Newton methods are one of the most popular approaches for the solution of inverse problems in differential equations. Since these problems are usually ill‐posed, an appropriate stopping rule is an essential ingredient of such methods. In this paper we suggest an a‐posteriori stopping rule of Lepskij‐type which is appropriate for data perturbed by random noise. The numerical results for this look promising. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coupling Techniques for Thermal and Mechanical Fluid‐Structure‐Interactions in Aeronautics
Authors: Haupt Matthias , Niesner Reinhold , Unger Ralf , Horst Peter
Published: November 2005

For the coupled thermal and mechanical analysis of spacecraft structures a simulation environment was developed containing the necessary coupling techniques. The numerical concept uses the weak form of the interface conditions on the coupling surface. The iterative solution of the coupled equations is based on the classical Dirichlet‐Neumann approach. Transient problems are handled with iterative staggered schemes. A flexible component‐based software environment combines existing fluid and structural analysis codes. Aspects of the architecture and its implementation are described. Finally an application to a spacecraft structure is shown. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of lower‐bound direct method to large‐scale problems
Authors: Hachemi Abdelkader , Mouhtamid Said , Weichert Dieter
Published: November 2005

In this paper, a lower‐bound direct method is presented for the large‐scale problems. This method is based on the statical shakedown analysis and nonlinear mathematical programming. Here, the interior point method combined with the method of difference of convex functions (IPDCA) is used to solve large‐scale problems. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Continuum Biomechanics Applied to the Human Intervertebral Disc
Authors: Ehlers W. , Karajan N. , Markert B. , Acartürk A.
Published: November 2005

Biomechanical problems are of growing importance for our society with respect to both the ongoing aging of people and the improvement of surgery techniques. As a result, there is an increasing interest in scientific biomechanics in order to understand and to describe the complex electro‐chemomechanical behaviour of biological tissues. In the present contribution, the methods of continuum biomechanics are applied to the human intervertebral disc (IVD) as one of the major load‐carrying mechanisms of the human spine.

As a naturally grown material, the IVD belongs to the class of soft avascular cartilaginous tissues consisting of mostly ionized water (interstitial fluid) and collagen of type I and II embedded in an extracellular meshwork of charged protein compounds. More precisely, the type I collagen is organized in fiber bundles building a fiber‐reinforced ring, the anulus fibrosus (AF), which encloses a highly charged gelatinous core, the nucleus pulposus (NP). Following this, the principle loadbearing mechanism of the disc emerges directly. Under compression, interstitial fluid pressure develops inside the NP forcing a lateral bulging, which is prevented by the AF with its collagen fibers under tension.

In the framework of continuum biomechanics, the IVD is modelled on the basis of the established Theory of Porous Media (TPM), which allows for the description of multicomponent continua with internal interactions and is proven to yield stable implementations within the mixed finite element method (FEM). Following this, one succeeds in describing the physiological behaviour of charged hydrated tissues. This includes the electro‐chemomechanical couplings as well as the viscoelastic and anisotropic properties of the extracellular matrix. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pore structures: Measurement, characterization and relevance for flow and transport in soils
Authors: Lehmann Peter
Published: November 2005

The geometry of the pore space determines the flow and transport properties of a soil under water saturated and unsaturated conditions. The spatial arrangement of the pores can be mapped using the appropriate tomographic technique. To understand the effect of the pore space on flow and transport, the complex pore structures must be quantified. To reveal the importance of various geometrical properties, porous media with well defined geometrical properties were numerically generated and were compared with a sand medium containing sphere‐like particles with sizes ranging from 80 to 1.250 µm. The spatial distribution of water and air was calculated for the optimized media and the sand packing to quantify the relevance of the geometric properties. In a first test, the sand packing was compared with a generated medium with identical Minkowski functionals. The resulting pores of the generated media were too large and the water retention was underestimated. In a second test, a medium with an optimized chord length distribution was generated and a good agreement with respect to water distribution was found. The chord length distribution is a more relevant property, because it takes into account the correlation of the system over large spatial distances. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimization of Discrete‐Continuous Dynamic Systems Based on Disjunctive Programming
Authors: Oldenburg Jan , Marquardt Wolfgang
Published: November 2005

In this contribution, a novel approach for the modeling and optimization of discrete‐continuous dynamic systems based on a disjunctive problem formulation is proposed. It will be shown that a disjunctive model representation, which constitutes an alternative to mixed‐integer model formulations, provides a very flexible and intuitive way to formulate discrete‐continuous dynamic optimization problems. Moreover, the structure and properties of the disjunctive process models can be exploited for an efficient and robust numerical solution by applying generalized disjunctive programming techniques. The proposed modeling and optimization approach will be illustrated by means of an optimal control problem that embeds a linear discretecontinuous dynamic system. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On a trust region method without exact Jacobian matrices
Authors: Walther Andrea
Published: November 2005

Automatic differentiation (AD) provides a possibility to evaluate exact derivative information within working accuracy. Here, we present an approach for equality constrained optimization that is based essentially on AD by computing only direct sensitivities and adjoints of first and second order. Employing this information, we generate approximations of the required derivative matrices using the STR1 update instead of computing the full constraint Jacobian or the full Lagrangian Hessian at each iteration explicitly. Hence, this approach avoids the forming and factoring of the exact constraint Jacobian that is often required in each iteration step.

In order to globalize this provable local convergent method, the algorithm was embedded in a trust‐region framework. We apply a composite‐step method similar to the Byrd‐Omojokun approach that is well suited for the available information from the approximated matrices. For that purpose, the normal step is given by the dogleg method whereas a generalized CG‐iteration is applied to compute the tangential step. Here, the fact that only inexact information of the constraint Jacobian is available forms the main difference to other existing algorithms, where often a factorization of the exact Jacobian is used.

Numerical results are shown for an equality constrained problem of the CUTE set and a PDE‐based optimization problem. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation Based Determination of Piezoelectric Material Parameters
Authors: Lahmer Tom , Kaltenbacher Barbara , Mohr Marcus
Published: November 2005

The exact numerical simulation of piezoelectric transducers needs the knowledge of all material tensors that occur in the piezoelectric constitutive relations. The determination of these tensors is achieved by a simulation based algorithm which adjusts the 3D ‐ FEM simulated data with electrical measurements of a piezoelectric transducer. Its advantage compared to the standards (see [1], [2]) lies in the fact that a determination of the complete set of material parameters from one arbitrarily shaped specimen with a high precision is possible. The reconstruction of the material tensors is formulated as a parameter identification problem for a system of PDEs. Since unique solvability of this inverse problem may hardly be verified, the system of equations we have to solve for recovering the material tensor entries can be rank deficient and therefore requires application of appropriate regularization strategies. For this purpose, we use inexact Newton methods. The material parameters are assumed to be complex‐valued which allows to account for mechanical, dielectric and piezoelectric losses. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)