Search Results - (Author, Cooperation:M. Wegmann)

2015-07-24

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; *Biodiversity ; Conservation of Natural Resources/methods ; Ecological Parameter Monitoring/instrumentation/*methods ; Ecology/instrumentation/*methods/standards ; Environmental Policy ; *Satellite Imagery

2013-01-19

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Alleles ; *Biodiversity ; *Environmental Monitoring ; Genetic Variation ; Population

2018-07-13

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

1089-7550

AIP Digital Archive

Physics

The effects of magnetic alignment, heat treatment, and substrate interactions on the microstructural development and properties of YBa2Cu3O7−x (Y123) thick films were studied. Aligned films were formed by vacuum filtrating a particulate suspension in a 7 T applied field. These films and nonaligned control films were fired on either platinum (Pt) foil or magnesium oxide (MgO) substrates to various maximum temperatures between 930 and 1040 °C. Optical microscopy revealed large differences in microstructural development between the various films. Aligned Y123 films fired on Pt foil exhibited the best microstructural properties. Via plasma emission spectroscopy and secondary ion mass spectroscopy, approximately 0.1 wt % Pt was found distributed throughout the films fired on platinum, while negligible amounts of Mg were detected in the films fired on MgO substrates. Differential thermal analysis revealed that, in the presence of Pt, the peritectic temperature (1030 °C for pure Y123 in O2) is reduced 70 °C, thereby opening a substantial thermal processing window for partial melt assisted growth of textured Y123. SQUID measurements of magnetic hysteresis and Tc provided quantitative evidence that, relative to the films fired on MgO, those fired on Pt exhibited enhanced texture development [ΔM(Happ(parallel)c axis)/ΔM(Happ⊥c axis)=2.6 at 5 K, 1 T] and properties (Bean model Jc,m=5×104 A/cm2 at 5 K, 4 T) without degradation of the Tc characteristics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Grain-aligned YBa2Cu3O7−x films were fabricated by vacuum filtration in an applied magnetic field (7 T). Platinum (Pt) was shown to lower the peritectic temperature of YBa2Cu3O7−x by almost 75 °C, leading to dramatic microstructural differences between films densified on MgO (single crystal) substrates and those densified on Pt foil to a maximum temperature of 1020 °C in oxygen. Superconducting quantum-interference device hysteresis loops measured at 0–5.5 T at 5 K showed that films fired on Pt had ΔM (Happ(parallel)c axis) values 15–60 times larger than those fired on MgO.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Textured YBa2Cu3O7−x thick films (thickness ≈1 mm) were fabricated by vacuum filtration in an applied magnetic field (H=7 T). Platinum (1 wt %) was incorporated to induce liquid phase-assisted densification in films fired between 960 and 1030 °C in oxygen. The transport critical current densities (Jct) of films fired to 1030 °C exhibited nearly field insensitive behavior between H=0–3 T (H(parallel)c-axis) at 77 K, with Jct≈2500 A/cm2 and corresponding critical currents (Ic) of nearly 100 A at H=1 T. © 1995 American Institute of Physics.

Electronic Resource

1365-2222

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Background Epidemiological evidence underlines the impact of prenatal environmental factors on the development of postnatal allergies. In this regard an inverse correlation between lipopolysaccharide (LPS) exposure and development of childhood allergy has been found.Objective To assess the impact of prenatal LPS exposure on the development of postnatal respiratory allergies in a mouse model of experimental asthma.Methods Female BALB/c mice were exposed to LPS before conception and during pregnancy. Several weeks after birth offspring were sensitized to ovalbumin (OVA) followed by aerosol allergen challenges.Results Prenatal, maternal LPS-exposure enhanced neonatal IFN-γ, but not IL-4 and IL-2 production. OVA sensitization of prenatally LPS-exposed mice was accompanied by a marked suppression in anti-OVA IgG1 and IgE as well as unchanged IgG2a antibody responses, paralleled by a significant reduction in IL-5 and IL-13 levels following mitogenic stimulation of splenic leucocytes. Assessment of bronchoalveolar lavage fluids following allergen challenges revealed a marked reduction in eosinophils and macrophages in these mice. Surprisingly, development of airway hyper-responsiveness, a hallmark of bronchial asthma, was not affected.Conclusion This study provides first experimental evidence that LPS may already operate in prenatal life in order to modulate the development of allergies in the offspring.

Electronic Resource

1365-2222

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Background Bronchial asthma is characterized by chronic airway inflammation and airway remodelling which occurs in both proximal and distal airways. These changes are associated with development of airway hyper-responsiveness and airflow limitation.Objective This study was aimed to analyse whether chronic inhalative allergen challenges in mice lead to morphological and physiological changes comparable with this phenotype.Methods For this purpose, BALB/c mice were systemically sensitized to ovalbumin (OVA) followed by aerosol allergen challenges on 2 consecutive days per week for 12 weeks.Results In chronically challenged mice, tissue inflammation in proximal as well as distal airways was observed with a predominance of lymphocytes within the cellular infiltrate. In contrast, inflammation in the airway lumen decreased over time. These changes were associated by a shift in bronchoalveolar lavage–cytokine levels from IL-4, IL-5 and TNF-α production (during the acute phase) towards markedly increased levels of TGF-β during the chronic phase. Goblet cell hyperplasia and subepithelial fibrosis occurred throughout the airway tree. In terms of lung function, chronically challenged mice developed persistent bronchial hyper-responsiveness and progressive airflow limitation. Six weeks after OVA aerosol discontinuation, airway inflammation still persisted although lung function was normalized.Conclusion These data indicate that our model of chronic aerosol allergen challenges leads to a phenotype of experimental asthma with participation of distal airways and persistence of inflammation thereby resembling many morphological and physiological aspects of human bronchial asthma.

Electronic Resource

1546-170X

Nature Archives 1869 - 2009

Biology

Medicine

[Auszug] A promising approach to reduce the impact of influenza is the use of an attenuated, live virus as a vaccine. Using reverse genetics, we generated a mutant of strain A/WSN/33 with a modified cleavage site within its hemagglutinin, which depends on proteolytic activation by elastase. Unlike the ...

Electronic Resource

1573-1480

Springer Online Journal Archives 1860-2000

Geosciences

Physics

Abstract The fourteenth century is known to include a period of winter cooling in Central and Western Europe, but its timing and magnitude are not clearly established. An attempt to obtain a coherent picture from verified documentary evidence yielded 2133 records from a region covering Central Europe and Northern Italy, mostly originating from the ‘Monumenta Germaniae Historica’. Temperatures were assessed using semi-quantitative indices on the basis of proxy information on snow-cover, ice and untimely activity of vegetation. Results: A run of cold winters from 1303 to 1328 was followed by a run of ‘average’ winters up to 1354. Then winter temperatures were extremely variable up to 1375. For the rest of the century they fluctuated somewhat below the average of the twentieth century. The pattern in the first five decades is compared to that in the Late Maunder Minimum (1675–1715). The possible role of forcing factors (variations in solar output, North Atlantic Deep Water formation) is briefly discussed.

Electronic Resource