Strain control of a bandwidth-driven spin reorientation in Ca3Ru2O7.

The layered-ruthenate family of materials possess an intricate interplay of structural, electronic and magnetic degrees of freedom that yields a plethora of delicately balanced ground states. This is exemplified by Ca3Ru2O7, which hosts a coupled transition in which the lattice parameters jump, the Fermi surface partially gaps and the spins undergo a 90∘ in-plane reorientation. Here, we show how the transition is driven by a lattice strain that tunes the electronic bandwidth. We apply uniaxial stress to single crystals of Ca3Ru2O7, using neutron and resonant x-ray scattering to simultaneously probe the structural and magnetic responses. These measurements demonstrate that the transition can be driven by externally induced strain, stimulating the development of a theoretical model in which an internal strain is generated self-consistently to lower the electronic energy. We understand the strain to act by modifying tilts and rotations of the RuO6 octahedra, which directly influences the nearest-neighbour hopping. Our results offer a blueprint for uncovering the driving force behind coupled phase transitions, as well as a route to controlling them.

Fluctuation-driven magnetic hard-axis ordering in metallic ferromagnets.

We demonstrate that the interplay between soft electronic particle-hole fluctuations and magnetic anisotropies can drive ferromagnetic moments to point along a magnetic hard axis. As a proof of concept, we show this behavior explicitly for a generic two-band model with local Coulomb and Hund's interactions and a spin-orbit-induced easy plane anisotropy. The phase diagram is calculated within the fermionic quantum order-by-disorder approach, which is based on a self-consistent free-energy expansion around a magnetically ordered state with unspecified orientation. Quantum fluctuations render the transition of the easy-plane ferromagnet first order below a tricritical point. At even lower temperatures, directionally dependent transverse fluctuations dominate the magnetic anisotropy, and the moments flip to lie along the magnetic hard axis. We discuss our findings in the context of recent experiments that show this unusual ordering along the magnetic hard direction.

An integrative approach to detect subtle trophic niche differentiation in the sympatric trawling bat species Myotis dasycneme and Myotis daubentonii.

Bats are well known for species richness and ecological diversity, and thus, they provide a good opportunity to study relationships and interaction between species. To assess interactions, we consider distinct traits that are probably to be triggered by niche shape and evolutionary processes. We present data on the trophic niche differentiation between two sympatric European trawling bat species, Myotis dasycneme and Myotis daubentonii, incorporating a wide spectrum of methodological approaches. We measure morphological traits involved in foraging and prey handling performance including bite force, weightlifting capacity and wing morphology. We then measure resulting prey consumption using both morphological and molecular diet analyses. These species closely resemble each other in morphological traits, however, subtle but significant differences were apparent in bite force and lift capacity, which are related to differences in basic body and head size. Both morphological and molecular diet analyses show strong niche overlap. We detected subtle differences in less frequent prey items, as well as differences in the exploitation of terrestrial and aquatic-based prey groups. Myotis dasycneme feeds more on aquatic prey, like Chironomidae and their pupal stages, or on the aquatic moth Acentria ephemerella. Myotis daubentonii feeds more on terrestrial prey, like Brachycera, or Coleoptera. This suggests that these bats use different microhabitats within the habitat where they co-occur.

Non-alcoholic fatty liver disease (NAFLD) in the Western Cape: a descriptive analysis.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease in Western countries, but the disease profile has not yet been described in South Africa. NAFLD affects all spheres of society, especially the poorest and least educated. Aim. To investigate the demographics and clinical and biochemical features of South African patients diagnosed with non-alcoholic fatty liver and non-alcoholic steatohepatitis (NASH) in the Western Cape, South Africa. DESIGN/METHOD: Overweight/obese subjects were screened by ultrasound and those with fatty liver/hepatomegaly were included. Liver biochemistry, insulin resistance (using the insulin resistance homeostasis model assessment method for insulin resistance, HOMA-IR) and body mass index were assessed and liver biopsies were performed on patients older than 45 years with persistently abnormal liver function and/or hepatomegaly. RESULTS: We screened 233 patients: 69% coloured, 25% Caucasian, 5% black and 1% Asian. The majority (73%) were female. NAFLD was confirmed histologically in 111 patients, of whom 36% had NASH and 17% advanced liver fibrosis. No black patient had advanced fibrosis. Subjects with NASH had higher mean triglyceride (p=0.03) and cholesterol (p=0.01) levels than subjects with NAFL. All patients were insulin resistant/diabetic. HOMA-IR and not the degree of obesity was strongly associated with advanced fibrosis (p=0.09). CONCLUSION: This study is the first to describe the clinical characteristics of NAFLD in South Africa, albeit only in the Western Cape population. Insulin resistance was the universal factor present. The degree of obesity was not associated with severity of disease. The role of genetic risk factors in disease development and severity remains to be defined.

Quantum-mechanical wavepacket propagation in a sparse, adaptive basis of interpolating Gaussians with collocation.

We present an extension of our earlier work on adaptive quantum wavepacket dynamics [B. Hartke, Phys. Chem. Chem. Phys., 2006, 8, 3627]. In this dynamically pruned basis representation the wavepacket is only stored at places where it has non-negligible contributions. Here we enhance the former 1D proof-of-principle implementation to higher dimensions and optimize it by a new basis set, interpolating Gaussians with collocation. As a further improvement the Tnum approach from Lauvergnat and Nauts [J. Chem. Phys., 2002, 116, 8560] was implemented, which in combination with our adaptive representation offers the possibility of calculating the whole Hamiltonian on-the-fly. For a two-dimensional artificial benchmark and a three-dimensional real-life test case, we show that a sparse matrix implementation of this approach saves memory compared to traditional basis representations and comes even close to the efficiency of the fast Fourier transform method. Thus we arrive at a quantum wavepacket dynamics implementation featuring several important black-box characteristics: it can treat arbitrary systems without code changes, it calculates the kinetic and potential part of the Hamiltonian on-the-fly, and it employs a basis that is automatically optimized for the ongoing wavepacket dynamics.

Dioxins and dioxin-like PCBs in different fish from the river Elbe and its tributaries, Germany.

In a long-term program polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) as well as dioxin-like polychlorinated biphenyls (DL-PCBs) were analyzed in the muscle tissue of eels (Anguilla anguilla), bream (Abramis brama), European chub (Leuciscus cephalus) and ide (Leuciscus idus) from the river Elbe and its tributaries Mulde and Saale. The variation of the PCDD/F and DL-PCB concentrations in all fish samples is very large, whereby the DL-PCBs predominate in comparison to the PCDD/Fs. In the eels, the concentrations (pg WHO-TEQ/g ww) for the PCDD/Fs lie in the range of 0.48-22 and for the DL-PCBs between 8.5 and 59. In the whitefish, the concentration range is 0.48-12 for the PCDD/Fs and 1.2-14 for the DL-PCBs. Statistical analysis using relative congener patterns for PCDD/Fs allow spatial correlations to be examined for sub-populations of eels and whitefish. The results are compared to the maximum levels laid down in the European Commission Regulation (EC) No. 466/2001 and the action levels of the European Commission Recommendation 2006/88/EC. Eels caught directly after the major flood in August 2002 as well as eels near Hamburg (years 1996 and 1998) show high concentration peaks. Compared to the eels whitefish is less contaminated with PCDD/Fs and DL-PCBs.

Spatial and temporal variability of sediment deposition on artificial-lawn traps in a floodplain of the River Elbe.

Artificial-lawn mats were used as sediment traps in floodplains to measure sediment input and composition during flood events. To estimate the natural variability, 10 traps were installed during two flood waves at three different morphological units in a meander loop of the River Elbe. The geochemical composition of deposited and suspended matter was compared. The sediment input showed weak correlations with concentration and composition of river water. It also correlated poorly with flood duration and level as well as distance of trap position from the main river. This is due to the high variability of the inundation, different morphological conditions and the variability of sources. The composition of the deposits and the suspended matter in the river water was comparable. Hence, for the investigated river reach, the expected pollution of the floodplain sediments can be derived from the pollution of the suspended matter in the river during the flood wave.

Spin-wave dispersion in orbitally ordered La1/2Sr3/2MnO4.

The magnon dispersion in the charge, orbital, and spin ordered phase in La1/2Sr3/2MnO4 has been studied by means of inelastic neutron scattering. We find excellent agreement with a magnetic interaction model based on the CE-type superstructure. The magnetic excitations are dominated by ferromagnetic exchange parameters revealing a nearly one-dimensional character at high energies. The strong ferromagnetic interaction in the charge or orbital ordered phase appears to be essential for the capability of manganites to switch between metallic and insulating phases.

Contamination of the alluvial plain, feeding-stuffs and foodstuffs with polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (DL-PCBs) and mercury from the River Elbe in the light of the flood event in August 2002.

Meadow soils, feeding-stuffs and foodstuffs from the alluvial plain of the river Elbe were analyzed in respect of PCDD/Fs, DL-PCBs and mercury with a view to assessing the consequences of the extreme flood of August 2002. The PCDD/F concentrations in the soils range from 3 to 2100 ng WHO-TEQ/kg dm, and for the DL-PCBs the range was 0.32 to 28 ng WHO-TEQ/kg dm. On the basis of established threshold values >40% of the areas are only fit for restricted usage. Mercury concentrations range from 0.11 to 17 mg/kg dm, whereby the action value of 2 mg/kg dm is exceeded in about 50% of the soil samples. A cumulative memory effect from past floods rather than a recent contamination from August 2002 is documented. Soils taken from behind broken dykes showed significantly lower concentrations. Grass, hay and grass silage originating from pasture land in Lower Saxony were taken before and immediately after the flooding. PCDD/Fs range from 0.29 to 16 ng WHO-TEQ/kg, the maximum permitted value of 0.75 ng WHO-TEQ/kg was exceeded in about 50% of the samples. Muscle-tissue from cattle, sheep, lamb and a roe deer as well as untreated milk from individual cows returned values ranging from 0.76 to 5.9 pg WHO-PCDD/F-TEQ/g fat, and 10% of the samples returned values higher than the permitted maximum of 3 pg WHO-PCDD/F-TEQ/g fat. The action value of 2 pg WHO-PCDD/F-TEQ/g fat was exceeded in 33% of the samples. No direct connection between these results and the effects of the flood could be established. A major input path for PCDD/Fs is the tributary Mulde, which discharges contaminated sediments from its catchment area into the Elbe.

Caustic injury to the upper GI tract.

Caustic injury of the oesophagus and stomach is common among children and young adults. The morbidity associated with caustic injury can be severe. Due to improved management the mortality has decreased significantly. Alkaline agents tend to cause more severe injury than acidic agents.

The Elbe flood in August 2002--occurrence of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/F) and dioxin-like PCB in suspended particulate matter (SPM), sediment and fish.

As a result of extreme precipitation in August 2002 major flooding occurred in the catchment area of the rivers Elbe, Vltava (Moldau) and Mulde. Pollutants from industrial sites and from municipal sewage treatment works (STW) entered the Elbe and led to a serious pollution problem in the river. PCDD/F concentrations (in pg WHO-TEQ/g dw) in SPM ranged from 7-150, in sediments from 3-140; the "safe sediment value" of 20 was exceeded in 46% of the samples. 24 eels showed a wide concentration variation for these contaminants. The WHO-PCDD/F+PCB-TEQ values lay in the range from 11-56 pg/g ww, whereby the WHO-PCB-TEQ values were several times higher than the WHO-PCDD/F-TEQ values. The maximum permitted value of 4 pg WHO-PCDD/F/g ww (EU Directive No. 2375/2001) was reached or exceeded in 54% of the individuals. A statistical analysis using data from SPM and sediment samples showed that in the Czech river section the flooding activated a contamination source in the vicinity of the Spolana works. The influence of the tributary Mulde could be clearly demonstrated. Only a major clean-up of the contaminated sites in Bitterfeld can lead to a mid to long term improvement in respect of PCDD/F and dioxin-like PCB input into the Elbe.

Long-term observation of the hypothalamic-pituitary-thyroid (HPT) axis in alcohol-dependent patients.

Thyroid hormone levels and thyrotrophin (TSH) were measured in 45 alcohol-dependent patients before detoxification and 8 days, 3 months and 6 months after detoxification, and compared to levels in healthy controls. Before detoxification, levels of thyroxine (T4) and thyroxine-binding globulin (TBG) were significantly reduced in patients compared with healthy controls, while triiodothyronine (T3), reverse T3, and TSH levels did not differ from those in healthy controls. During the entire observation period, free T4 (fT4) and free T3 (fT3) levels were slightly elevated compared with those in healthy controls. T4 and TBG levels increased significantly during the first week of abstinence. Severity of withdrawal symptoms was negatively correlated with the total T4 levels after 8 days of abstinence. Three months after detoxification, relapsers displayed significantly lower T4 and TBG levels compared with abstinent patients. The increase in T3 levels was most pronounced between 8 days and 3 months of abstinence in both relapsing and abstinent patients. Six months after detoxification, only abstinent patients could be assessed, and they displayed increased TBG and T3 levels compared to healthy controls. Our findings suggest a different time-course for T3 and T4 levels after detoxification in alcohol-dependent patients, and indicate that T4 levels after detoxification interact with withdrawal symptoms.

ITS2 ribosomal RNA indicates Schistosoma hippopotami is a distinct species.

The internal transcribed spacer region of the ribosomal RNA, ITS2, was sequenced from a single specimen of S. hippopotami collected from a pulmonary artery of the hippopotamus, Hippopotamus amphibius in South Africa. The nucleotide sequence was aligned with those of S. mansoni, S. rodhaini, S. haematobium, S. intercalatum, S. curassoni, S. bovis and S. japonicum. Both maximum parsimony and genetic distance analyses were performed on these data sets. Using S. japonicum as outgroup to the African schistosomes, a single most-parasmonious tree was obtained of length 64 steps with a consistency index of 1-S. hippopotami was the sister-group to the remaining African species. This species has lateral-spined eggs and its basal position in the tree suggests that this condition is primitive and that terminal-spined eggs developed secondarily. Molecular data clearly show that S. hippopotami cannot be considered synonymous with S. mansoni. Assuming the hippopotamus is the normal host of S. hippopotami, phylogenetic analysis is consistent with an ancient association between schistosomes and ungulates.

Evidence for prolonged recovery of dopaminergic transmission after detoxification in alcoholics with poor treatment outcome.

It has been hypothesized that dysfunction of dopaminergic neurotransmission is involved in the pathogenesis of alcohol addiction. Therefore, peripheral dopamine levels, sensitivity of central dopamine receptors (apomorphine-induced Growth Hormone (GH) secretion), and the inhibitory efficacy of G-proteins on adenylyl cyclase activity (as an indicator for dopamine D2-receptor coupled second messenger mechanisms) were measured in 45 alcohol-dependent patients before and after detoxification and in 10 healthy controls. The time needed to adjust to abstinence conditions differed between patients with good and poor treatment outcome. In subsequent abstainers, effects of alcohol withdrawal were already found during the first 24 hours of abstinence (normalisation of GH response, increases in dopamine levels and the inhibitory efficacy of G-proteins). During the next 7 days of abstinence, no more significant changes were observed in the assessed variables. In subsequent relapsers, no significant effect of acute ethanol withdrawal on the same measures was found. However, at day 8 of abstinence, increases in apomorphine-induced GH secretion (towards normalisation), in dopamine plasma levels, and in the inhibitory efficacy of G-proteins (towards above-normal levels) were observed. This retarded adjustment of dopaminergic signal transduction seems to reflect the relapse risk of treatment nonresponders.

Photoconverted carbocyanine DiI allows direct visualization of transplanted glial cells at the ultrastructural level.

We have used the carbocyanine fluorochrome, DiI, to trace living glial cells (astrocytes, oligodendrocytes and immortalized Schwann cells) after their transplantation into the newborn shiverer and normal mouse brain. DiI fluorescence first detected on vibratome sections, was photoconverted into a stable, non-diffusible and electron-dense diaminobenzidine product. Both fluorescence and precipitate were found in the same cells and were detectable until 60 days after transplantation. At the ultrastructural level, DiI precipitate was contained within cytoplasmic vesicles scattered in the transplanted cell bodies and processes. Photoconversion did not interfere with the cell fine structure or predicted post-transplantation behavior. DiI is thus a suitable marker to trace, at the ultrastructural level, living cells after their transplantation.

Further studies on the susceptibility of Bulinus africanus to infection with Schistosoma haematobium.

Genetic manipulation of the intermediate host snails of schistosomiasis has been proposed as a possible method of reducing the rate at which the parasite is transmitted to the final host. This technique is based on the finding that snail-schistosome compatibility is variable, and that refractory snails could be introduced into natural habitats in an attempt to change existing highly-susceptible populations into non-susceptible ones. In our search for such a refractory snail population, offspring from eight different Bulinus africanus populations were infected with Schistosoma haematobium, isolated from school children in the Nelspruit district. A great variation in minimum prepatent period was recorded (33-55 days), while the infected snails surviving that period ranged from 22-89%. A significant difference was found between the infection rates of B. africanus from Newlands in Natal and those of the other seven populations from the Eastern Transvaal Lowveld. The former population could be regarded as partially refractory, and none of the other populations proved to be completely refractory, to infection.

Tracing transplanted oligodendrocytes during migration and maturation in the shiverer mouse brain.

Fragments of neural tissue from normal newborn mouse were stained with Hoechst 33342 dye before transplantation into the newborn shiverer mouse brain. Combination of this technique with immunohistochemistry demonstrated that, after transplantation, these cells are able to survive as long as unstained cells and to myelinate in the shiverer mouse host brain. Stained cells express the normal sequence of differentiation in terms of chronology of differentiation marker expression [04, galactocerebroside (GalC), myelin basic protein (MBP)], as normal cell do in situ. It has thus been possible by this technique to show the migration pathways of transplanted cells and to correlate them with the expression of specific markers: long distance migration along white matter axonal pathways occurs when cells are o4-positive, GalC-negative. By contrast, only GalC-positive cells are able to migrate across the grey matter in the absence of radial glia. Finally, it has been possible to propose a migration and differentiation sequence of these cells, suggesting that MBP-positive oligodendrocytes divide after migration in the target zone.