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Soil quality determines the ability of soil to deliver ecosystem services and can be inferred from physical, biological and chemical indicators either in isolation or in combination. Earthworms are good soil-quality indicators that contribute to both chemical and physical quality by maintaining soil structure and cycling nutrients. The presence of dung pats can increase earthworm abundance locally and consequently the network of pores that they create through their burrowing activity. Inevitably this affects soil structure and consequently will have a spatially distributed effect on soil physical quality (SPQ). The aim of this field study was to examine the relationship between SPQ and earthworm abundance under dung and non-dung pat areas from deposition to decay and beyond. The present spatial and temporal study compared SPQ indicator (integral air-water energy, AWr) results with earthworm abundance across control and simulated dung pat treatments. Results showed that existing earthworm populations in this grassland were already very large (>500 individuals m-2) and SPQ (AWr) remained in the ‘very good’ category throughout the experiment. Earthworm abundance under dung pats and SPQ exhibited a significant (P = 0.05) temporal trend. In general, the time of decay of the dung pats played a role in increasing earthworm abundance and SPQ. Earthworm abundance and macropore density data formed a similar, ‘hump’-shaped dynamic over time. However, when an earthworm abundance threshold was exceeded (equivalent to about >3000 individuals m-2), the increase of SPQ under dung was attenuated and did increase further only under the control sward with high earthworm abundance. After 11 weeks, for both treatments, AWr under dung pats was capped at 0.83% and AWr under control sward peaked at 1.34%. Future work should focus on (a) further exploration of the threshold where earthworm abundance becomes detrimental for SPQ and (b) using the AWr SPQ indicator within an actual grazed trial which incorporates a gradient of soil degradation.

Core IdeasSoil quality indicators such as Sand PAWC are considered as static indicators with low sensitivity.The soil quality indicator AWris considered a dynamic indicator with high sensitivity.Indirect pedotransfer function based SWRCs are appropriate for static baseline indicators.Soil monitoring programs should use AWras a sensitive and reliable soil quality indicator. The quality of a soil is its ability to deliver functions providing ecosystem services, human health and well‐being. Soil physical quality (SPQ) values use different parts of the soil water retention curve (SWRC) to calculate SPQ. For example, the plant available water capacity (PAWC) method is the difference in water content between permanent wilting point and field capacity. The S‐index uses the slope of the SWRC at its inflection point and the relative air‐water energy (AWr) is the integral of “dry” divided by the “wet” area of the SWRC. Increasing demand for soil monitoring policies calls for reliable and sensitive soil quality indicators (SQIs). The objectives of the study were to assess the sensitivity and applicability of SPQ indicators using direct and indirect data inputs. The indirect approach provided sufficient data complexity for the PAWC and S‐index values, but the more complex AWrrequired the direct approach. PAWC and S‐index values were identified as static SPQ indicators. The values obtained from these approaches should be used to form baseline static datasets and therefore have an indicative role only. The AWrvalue was identified as a dynamic SPQ indicator and provided required sensitivity to pick up temporal changes in SPQ. This indicator could be used at multiple scales and could even guide grassland management in terms of SPQ. Higher SWRC data resolution will require more complex hydraulic models to fit and will ultimately improve the accuracy of soil hydraulic data and improve the sensitivity of AWras a SPQ indicator.

Deep cooling of electron and nuclear spins is equivalent to achieving polarization degrees close to 100% and is a key requirement in solid-state quantum information technologies. While polarization of individual nuclear spins in diamond and SiC (ref. ) reaches 99% and beyond, it has been limited to 50–65% for the nuclei in quantum dots. Theoretical models have attributed this limit to formation of coherent ‘dark’ nuclear spin states but experimental verification is lacking, especially due to the poor accuracy of polarization degree measurements. Here we measure the nuclear polarization in GaAs/AlGaAs quantum dots with high accuracy using a new approach enabled by manipulation of the nuclear spin states with radiofrequency pulses. Polarizations up to 80% are observed—the highest reported so far for optical cooling in quantum dots. This value is still not limited by nuclear coherence effects. Instead we find that optically cooled nuclei are well described within a classical spin temperature framework. Our findings unlock a route for further progress towards quantum dot electron spin qubits where deep cooling of the mesoscopic nuclear spin ensemble is used to achieve long qubit coherence. Moreover, GaAs hyperfine material constants are measured here experimentally for the first time.

In the present paper, we aim to show the interest of combining Multiwavelength Anomalous Diffraction (MAD) and Diffraction Anomalous Fine Structure (DAFS) spectroscopy, in grazing incidence, to obtain structural properties (composition, strain and atomic ordering) of semiconductor heterostructures and nanostructures. As an example we report on preliminary results obtained on a series of Ge/Si(001) nano-island samples: pyramides and domes on nominal and prepatterned surfaces. For free standing domes, it is shown that the Ge content strongly depends on the growth condition with a tendency to increase from the bottom to the top of the nano-islands. There is also some indication of atomic ordering in the upper part of the islands. For small, capped pyramids, we show that the Diffraction Anomalous Fine Structure spectroscopy is the unique non destructive method that allows to recover the actual Ge content, the in-plane and out-of-plane strain and to detect atomic ordering.

We report on studies of strain and composition of two-dimensionally ordered SiGe islands grown by molecular beam epitaxy using high resolution x-ray diffraction. To ensure a small size distribution of the islands, pit-patterned 4''(001) Si wafers were used as substrates. The Si wafers were patterned by optical lithography and reactive ion etching. The pits for island growth are ordered in regular 2D arrays with periods ranging from 500 to 1000 nm along two orthogonal 〈110〉 directions. After the growth of a Si buffer layer, 5 to 9 monolayers of Ge are deposited, leading to the formation of islands with either dome- or barn shape, depending on the number of monolayers deposited. The Si capping of the islands is performed at low temperatures (300○C) to avoid intermixing and thus strain relaxation. Information on the surface morphology obtained by atomic force microscopy (AFM) was used to set up models for three-dimensional Finite Element Method (FEM) simulations of the islands including the patterned Si substrate. In the model, special attention was given to the non uniform distribution of the Ge content within the islands. The FEM results served as an input for calculating the diffracted x-ray intensities using kinematical scattering theory. Reciprocal space maps around the vicinity of symmetric (004) and asymmetric (113) and (224) Bragg peaks were recorded in coplanar geometry. Simulating different germanium gradients leads to altered scattered intensity distribution and consequently information on this quantity is obtained for both dome- and barn-shaped islands as well as on the strain fields.

We performed a detailed theoretical study of the magneto-optical polar Kerr effect in magnetoplasmonic heterostructures consisting of a plasmonic film and a ferromagnetic layer with a corrugated top surface. Explicit analytical expressions allowing us to calculate the modifications of the polar Kerr effect in dependence on the thickness of the plasmonic and ferromagnetic layers as well as on the period and depth of the corrugation were derived. Interestingly, when applied to the test system of an Au/Co bilayer, our calculations show that the presence of corrugations is beneficial, as it allows us to tailor the magneto-optical response in a magnetoplasmonic composite in a resonant manner. This opens the possibility to enhance the strength of the Kerr effect by several orders of magnitude, which is beneficial for the investigation of systems in which magneto-optical responses are rather small, i.e., for characterization of biological or medical systems.

We developed a self-consistent analytical approach to describe the optical response of a magnetoplasmonic heterostructure upon surface plasmon polariton (SPP) excitation. The approach is based on the effective susceptibility concept in the frame of the Green’s function method and accounts for the local-field effects in the system. The formalism was applied to describe the polar Kerr effect in magnetoplasmonic bilayers consisting of Co and Au on an attenuated total reflection prism. It is demonstrated that the excitation of the SPP in the plasmonic film can lead to an enhancement of the Kerr effect. Analysis performed for the s- and p-polarized incident radiation showed that the enhancement of the Kerr effect is of resonant character, and it is observed when the incident angle of the probing light is close to the angles of the SPP excitation. Thickness-dependent study revealed that the largest enhancement of the Kerr effect is observed for rather thin magnetic layers in the range of couple of nanometers.

Stable isotope ratio analysis of light elements (including C, N, and S) is a powerful tool for inferring the production and geographic origins of animals. The objectives of this research were to quantify experimentally the isotopic turnover of C, N, and S in bovine skeletal muscle (LM and psoas major) and to assess the implications of the turnover for meat authentication. The diets of groups (n = 10 each) of beef cattle were switched from a control diet containing barley and unlabelled urea to an experimental diet containing maize, 15N-labeled urea, and seaweed for periods of up to 168 d preslaughter. The feeding of the experimental diet was clearly reflected by the δ13C, δ15N, and δ34S values of the LM and psoas major muscles, but isotopic equilibrium was not reached in either muscle for C, N, or S after 168 d of feeding the experimental diet. The slow turnover in skeletal muscle was reflected by the C and N half-lives of 151 and 157 d for LM and 134 and 145 d for psoas major, respectively, and by an S half-life of 219 d in LM. It is concluded that the turnover of light elements (C, N, and S) in bovine skeletal muscles is a slow process; therefore, skeletal muscles contain isotopic information on dietary inputs integrated over a long period of time (months to years).

Abstract: We report on studies of strain and composition of two-dimensionally ordered SiGe islands grown by molecular beam epitaxy using high resolution x-ray diffraction. To ensure a small size distribution of the islands, pit-patterned $4''$ (001) Si wafers were used as substrates. The Si wafers were patterned by optical lithography and reactive ion etching. The pits for island growth are ordered in regular 2D arrays with periods ranging from 500 to 1000 nm along two orthogonal 〈110〉 directions. After the growth of a Si buffer layer, 5 to 9 monolayers of Ge are deposited, leading to the formation of islands with either dome- or barn shape, depending on the number of monolayers deposited. The Si capping of the islands is performed at low temperatures (300○C) to avoid intermixing and thus strain relaxation. Information on the surface morphology obtained by atomic force microscopy (AFM) was used to set up models for three-dimensional Finite Element Method (FEM) simulations of the islands including the patterned Si substrate. In the model, special attention was given to the non uniform distribution of the Ge content within the islands. The FEM results served as an input for calculating the diffracted x-ray intensities using kinematical scattering theory. Reciprocal space maps around the vicinity of symmetric (004) and asymmetric (113) and (224) Bragg peaks were recorded in coplanar geometry. Simulating different germanium gradients leads to altered scattered intensity distribution and consequently information on this quantity is obtained for both dome- and barn-shaped islands as well as on the strain fields.

Abstract: In the present paper, we aim to show the interest of combining Multiwavelength Anomalous Diffraction (MAD) and Diffraction Anomalous Fine Structure (DAFS) spectroscopy, in grazing incidence, to obtain structural properties (composition, strain and atomic ordering) of semiconductor heterostructures and nanostructures. As an example we report on preliminary results obtained on a series of Ge/Si(001) nano-island samples: pyramides and domes on nominal and prepatterned surfaces. For free standing domes, it is shown that the Ge content strongly depends on the growth condition with a tendency to increase from the bottom to the top of the nano-islands. There is also some indication of atomic ordering in the upper part of the islands. For small, capped pyramids, we show that the Diffraction Anomalous Fine Structure spectroscopy is the unique non destructive method that allows to recover the actual Ge content, the in-plane and out-of-plane strain and to detect atomic ordering.

We report on studies of strain and composition of two-dimensionally ordered SiGe islands grown by molecular beam epitaxy using high resolution x-ray diffraction. To ensure a small size distribution of the islands, pit-patterned 4? (001) Si wafers were used as substrates. The Si wafers were patterned by optical lithography and reactive ion etching. The pits for island growth are ordered in regular 2D arrays with periods ranging from 500 to 1000?nm along two orthogonal ?110? directions. After the growth of a Si buffer layer, 5 to 9 monolayers of Ge are deposited, leading to the formation of islands with either dome- or barn shape, depending on the number of monolayers deposited. The Si capping of the islands is performed at low temperatures (300?C) to avoid intermixing and thus strain relaxation. Information on the surface morphology obtained by atomic force microscopy (AFM) was used to set up models for three-dimensional Finite Element Method (FEM) simulations of the islands including the patterned Si substrate. In the model, special attention was given to the non uniform distribution of the Ge content within the islands. The FEM results served as an input for calculating the diffracted x-ray intensities using kinematical scattering theory. Reciprocal space maps around the vicinity of symmetric (004) and asymmetric (113) and (224) Bragg peaks were recorded in coplanar geometry. Simulating different germanium gradients leads to altered scattered intensity distribution and consequently information on this quantity is obtained for both dome- and barn-shaped islands as well as on the strain fields.

In the present paper, we aim to show the interest of combining Multiwavelength Anomalous Diffraction (MAD) and Diffraction Anomalous Fine Structure (DAFS) spectroscopy, in grazing incidence, to obtain structural properties (composition, strain and atomic ordering) of semiconductor heterostructures and nanostructures. As an example we report on preliminary results obtained on a series of Ge/Si(001) nano-island samples: pyramides and domes on nominal and prepatterned surfaces. For free standing domes, it is shown that the Ge content strongly depends on the growth condition with a tendency to increase from the bottom to the top of the nano-islands. There is also some indication of atomic ordering in the upper part of the islands. For small, capped pyramids, we show that the Diffraction Anomalous Fine Structure spectroscopy is the unique non destructive method that allows to recover the actual Ge content, the in-plane and out-of-plane strain and to detect atomic ordering.

We report on the morphological evolution of strained SiGe islands epitaxially grown on Si(001). After reviewing the morphological transitions undergone by the islands as their size changes, we present recent results obtained by an approach consisting of “reading the footprints” left by the islands on the Si substrate during growth. Such footprints, which we investigate by a combination of scanning probe microscopy and selective wet chemical etching, are trenches carved in the Si substrate. The study of these trenches allows us to discuss general phenomena occurring during growth or post-growth annealing, such as coarsening and morphological transitions, surface-mediated material intermixing and lateral island motion, evolution of plastically relaxed islands and effect on the islands surrounding them. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Untersucht wurden die Letaltemperaturen von acht Hausfäulepilzen. Alle Pilze vertrugen in getrockneten Holzproben deutlich höhere Temperaturen als auf Agar: Donkioporia expansaund die Gloeophyllum-Arten überlebten vier Stunden 95°C, Antrodia vaillantiiund Oligoporus placenta80°C, Leucogyrophana molluscaund Coniophora puteana70°C und Serpula lacrymans65°C. Diese Befunde werden im Hinblick auf Heißluftbehandlungen diskutiert. Laborversuche und Beobachtungen aus über 40 Hausschwammbefällen in Gebäuden im Hamburger Raum zeigten nur geringen Wassertransport durch das Mycel. Bei S. lacrymanslag die maximale Befeuchtungsgeschwindigkeit bei drei Millimetern pro Woche. Die minimale Holzfeuchtigkeit für den Abbau von Kiefernholz betrug für S. lacrymans26,2% u, das Optimum in der Initialphase 35–55% u und bei stärkstem Holzabbau 45–90% u; das Maximum lag über 220% u. Insgesamt wurden 37 verschiedene Hausfäulepilze nachgewiesen, sechs davon erstmals. S. lacrymanswar der häufigste Pilz. In Gebäuden scheint sich eine Verschiebung im Artenspektrum zu Pilzen mit höheren Feuchtigkeitsansprüchen abzuzeichnen, die auch das Vorkommen von Schleimpilzen einschließt. Ein Zusammenhang mit dem verstärkten Wärmeschutz in Altbauten wird vermutet. The effect of increased temperatures was investigated for eight indoor wood decay fungi. All fungi survived in dried wood sticks at significantly higher temperatures than mycelium on malt agar. Donkioporia expansaand the Gloeophyllumspecies survived four hours at 95°C. Antrodia vaillantiiand Oligoporus placentasurvived at 80°C whereas Leucogyrophana molluscaand Coniophora puteananot above 70° and the true dry rot Serpula lacrymansnot above 65°C. The results are discussed with regard to the treatment of buildings with hot air. Laboratory tests and observations from over 40 attacks in buildings of the area of Hamburg were evaluated. For S. lacrymans, only a slight transport of water through the mycelium could be detected. The maximum humidification speed of this fungus was three millimetres per week. The minimal measured wood moisture of pinewood for wood decay was 26.2% u. The optimal moisture for wood decay by S. lacrymanswas 35–55% u in the initial phase and 45–90% u later. The maximum wood moisture with wood mass loss greater than 2% was more than 220% u. Thirty-seven different fungi were found in buildings. Six fungi have been shown for the first time in buildings. The true dry rot fungus was the most frequent fungus with a frequency of about 46%. In buildings, the spectrum of the species seems to change. Fungal species demanding relatively higher moisture are again found more frequently these days. The occurrence of slime fungi also seems to rise. The possible connection with the higher thermoprotection in old buildings after reconstructions is discussed.

Aims:One of the most significant surgical complications following rectal resection with primary anastomosis is anastomotic leakage. The aim of this study was to evaluate the benefit of intraoperative anastomotic testing of stapled anastomoses and the impact on leakage rate.

SummaryAntrodia vaillantii(DC.: Fr.) Ryv., A. serialis(Fr.) Donk, A. sinuosa(Fr.) P. Karsten, A. xantha(Fr.: Fr.) Ryv. and Oligoporus placenta(Fr.) Gilb.& Ryv. form a group of internal brown-rot fungi (‘Porenschwämme’), which are associated with decay of coniferous woodwork in buildings and timber in ground contact. The fungi have similar occurrence, biology, fruit bodies and mycelia. Their nomenclature has a confusing history and is still not uniform. For a better understanding of the domestic pore fungi and for a reliable species differentiation and identification of isolates, the internal transcribed spacer (ITS) of the ribosomal DNA (rDNA) was amplified by polymerase chain reaction and sequenced. Isolates from decayed wood and from culture collections were used. The ITS sequences characteristic of A. vaillantii, A. serialis,A. sinuosa, A. xanthaand O. placentawere obtained and deposited in the international databases. The ITS size ranges from 636 to 668 bp. Intraspecific variation was low. A dendrogram was performed for the phylogenetic relationship. Some isolates obtained mislabelled were named correctly according to the ITS sequence. The sequences contribute to our collection of ITS data from internal wood decay fungi made to characterize fungi in culture.

Stable isotope tracers are a promising tool for investigating the ecology of terrestrial slugs, including predator-prey relationships, migration behaviour, nutrient turnover and dietary routing. The objective of the present feasibility study was to label two economically important slug groups, Deroceras reticulatumand keeled slugs (families Limacidae and Milacidae, respectively), with the stable isotope 15N under controlled laboratory conditions. Significant isotopic enrichment in slug tissue was detected after 4 days and persisted for at least 10 days after slugs had been fed on 15N enriched food for a period of 15 days. The time course of 15N uptake into slug tissues and its relation to food consumption were well described mathematically. Estimated mean 15N assimilation efficiencies from labelled maize mixed with unlabelled wheat bran were 30 and 38, respectively, for the species groups studied. These findings suggest that slugs can be readily and efficiently labelled and that it is feasible to devise protocols for producing large numbers of isotopically labelled slugs for use in ecological studies. A simple method is described for the collection and analysis of cutaneous mucus from individual slugs which can be used to test uniformity of isotopic labelling.

SummaryWithin the genus Coniophora, C. puteanaand the less common species C. marmorata, C. aridaand C. olivaceaform a group of domestic brown-rot fungi (“cellar fungi”), which cause considerable decay in the woodwork of buildings. The fungi are difficult to distinguish by their fruit bodies. Traditional methods fail to identify species in a pure culture. Also with regard to decay of wood in use, the basidiomes rarely develop, and the surface mycelium on wood is sparse except for the fine dark strands. Thus, molecular techniques were applied to obtain a reliable method for differentiation and detection and to aquire a greater knowledge of the domestic Coniophoraspecies. Isolates obtained from decayed wood and from culture collections and identified as domestic Coniophoraspecies were used. The internal transcribed spacer (ITS) of the ribosomal DNA was amplified by polymerase chain reaction, sequenced and restricted by the endonuclease TaqI. The ITS sequences characteristic of C. puteana, C. arida, C. marmorataand C. olivaceawere obtained and entered into the international databases. The sequence size ranges from 525 to 729 bp. The data supplement our collection of ITS sequences from domestic wood decay fungi built for the characterization of mycelium in culture. Most isolates belong to C. puteanaand some to C. arida, C. marmorataand C. olivacea. Two other isolates belong to a further Coniophoraspecies close to C. olivacea. Obviously, at least five Coniophoraspecies occur within European buildings. Many of the isolates were not correctly identified. Consequently, the traditional characterization methods used, viz., growth rate, temperature influence and wood weight loss, were less suitable for the differentiation of Coniophoraspecies as formerly anticipated.

Abstract: To identify building-rot fungi in culture and from rot host tissue, the rDNA-ITS region of 18 species was determined by PCR and sequencing: Serpula lacrymans, S. himantioides, Meruliporia incrassata, Leucogyrophana mollusca, L. pinastri, Coniophora puteana, C. arida, C. marmorata, C. olivacea, Antrodia vaillantii, A. serialis, A. sinuosa, A. xantha, Oligoporus placenta, Donkioporia expansa, Gloeophyllum abietinum, G. sepiarium, and G. trabeum. Sequences were deposited in the international databases. Unknown samples can be identified via homology.

The magnetic domain structure in Permalloy (Ni₈₁Fe₁₉) micropatterns (10–100 μm) on NiO has been investigated by means of soft x-ray photoemission electron microscopy. The exchange anisotropy between the Ni₈₁Fe₁₉ patterns and the NiO layer results in the formation of complex domain structures which markedly differ from the simple Landau–Lifshitz configurations. The domain structures reflect the competition between the exchange anisotropy and the dipole–dipole interaction in a weakly coupled system. The observed domain structures change with the feature size, as the domain patterns lose complexity in the smaller structures.

Pb particles on a Si(111) substrate were investigated using a photoemission electron microscope (PEEM). The electrons have been excited by a linearly polarised femtosecond laser beam with a wavelength of λ = 400 nm. The PEEM images exhibit an unusually high contrast. They arise due to photoemission being of a nontrivial nature because the photon energy is lower than the work function of the sample. It may be caused by the following processes: two- or multi-photon absorption, tunnel-photoeffect induced by a strong lowering of the potential barrier owing to enhancement of the electrical field of the powerful incident light wave on a rough surface, generation of second harmonic with its following absorption, or electron gas heating. Images obtained with orthogonal directions of the photon polarisation were compared to estimate the shape of different Pb particles. The size of the islands was determined by two methods, either from the shape of the spatial brightness distribution or from the area under the curve of this distribution.

Pb particles on a Si(111) substrate were investigated using a photoemission electron microscope (PEEM). The electrons have been excited by a linearly polarised femtosecond laser beam with a wavelength of λ = 400 nm. The PEEM images exhibit an unusually high contrast. They arise due to photoemission being of a nontrivial nature because the photon energy is lower than the work function of the sample. It may be caused by the following processes: two‐ or multi‐photon absorption, tunnel‐photoeffect induced by a strong lowering of the potential barrier owing to enhancement of the electrical field of the powerful incident light wave on a rough surface, generation of second harmonic with its following absorption, or electron gas heating. Images obtained with orthogonal directions of the photon polarisation were compared to estimate the shape of different Pb particles. The size of the islands was determined by two methods, either from the shape of the spatial brightness distribution or from the area under the curve of this distribution.

The alloying and oxygen reduction at titanium silicon interfaces were studied by means of photoemission microscopy. The microscopic chemical composition of the sample surface was characterised by means of imaging X-ray absorption. The silicide formation was studied at clean and oxidised silicon substrates both covered with micron-sized titanium patterns.

We investigated the surfaces of natural iron-based minerals that are magnetite, hematite, goethite, pyrite, pyrrhotite, chalcopyrite, bornite and vivianite, using synchrotron radiation based techniques. Most iron chalkogenides are very suitable for photoemission microscopy studies due to their low resistivity, which prevents from surface charging. The local compositions were studied employing photoemission microscopy in combination with X-ray absorption spectroscopy. Imaging of the sample in the near-edge region of the absorption edges was used to visualise the spatial distributions of the chemical phases on the surface. Distributions of trace elements are imaged with high chemical and lateral resolution.

Multi-photon excitations from thin metallic films on silicon substrates have been observed utilising photoemission electron microscopy. The photoelectrons have been excited by means of high power femtosecond laser pulses with a photon energy below the work function threshold. The strong spatial variations of the non-linear effects became directly visible in electron emission from the adsorbed thin films. Centres of enhanced photoelectron yield, so-called hotspots, were observed on the surfaces of various samples. The multi-photon electron yield of the metallic films (permalloy and lead) depends strongly on the sample topography and the photon polarisation.

A comparative study was conducted on earthworm communities in a conventional winter wheat monocropping system and a low-input intercropping system in which successive crops of winter wheat were direct-drilled into a permanent white clover sward. Earthworm abundance, biomass and species composition under the two cropping systems in the second and third years of successive cropping were assessed each spring and autumn in farm-scale field plots at four sites using formalin and electrical extraction methods. The wheat-clover cropping system supported larger earthworm communities (overall mean abundance 548 individuals m?2, 137 g biomass m?2) than conventional wheat monocropping (194 individuals m-2, 36 g biomass m-2). Between one and five more earthworm species were recorded in the wheat-clover system than in the wheat system at three out of the four study sites. Wheat-clover cropping especially favoured species belonging to the epigeic and epigeicanecic ecological groups such as Lumbricus castaneus, L. festivus, L. rubellus, juvenile Lumbricusand Satchellius mammalis. Earthworm communities in the wheat-clover cropping system were comparable in size and species composition to communities normally found in perennial grassland-type habitats such as pastures and grass-legume leys.

Quantitative methods are needed for the assessment of the size and composition of earthworm communities. A poorly documented electrical sampling method, Thielemann's octet method, was compared with two long-established methods, formalin extraction and soil hand sorting, in conventional and direct-drilled wheat cropping systems at two sites with medium to heavy textured soils in Ireland. Under all agronomic conditions tested, the electrical method extracted significantly higher earthworm numbers than formalin, but earthworm biomasses were not significantly different. When used routinely over two years during periods of high earthworm activity, the electrical method yielded community estimates that were comparable in both size and species composition to those obtained by soil hand sorting (25 cm depth), except in recently ploughed land. However, Murchieona minuscule, a minute endogeic species, was underestimated by electrical extraction. It is concluded that the electrical octet method can be a reliable and useful alternative to other dynamic methods for estimating earthworm populations, especially in situations where minimum soil disturbance is desirable.

We have calculated the static and frequency-dependent polarizability tensors of a series of (5,5)- and (9,0)-carbon nanotubes. The calculations have been performed by a dipole−dipole interaction model based on classical electrostatics and an Unsöld dispersion formula. The model has previously been shown to predict successfully the frequency-dependent polarizability tensors of both aliphatic and aromatic molecules. In comparison we have carried out ab initio calculations at the Hartree−Fock level of the static polarizability of C60, C70, and the smaller carbon nanotubes using the STO-3G basis set. We find that the interaction model is in good agreement with the self-consistent field calculations and can be used to predict the polarizability tensors of carbon nanotubes. In addition, we find that the symmetry and intramolecular geometry of the tube have great influence on the polarizability.

Abstract: In chemical shift resolved spectroscopic imaging (CSI) temporal changes in the static magnetic field (drift) can lead to distortions of the phase encoding process. This can result in localization artifacts. The extent of the artifact depends on the size of the drift, the number of acquisitions, as well as on the combination of the size of the field of view and the number of phase encoding gradient steps. Furthermore, it is affected by the succession of the phase encoding gradients. Precautions are described which allow substantial minimization of the artifact.