210 research outputs found
Electronic disorder of P- and B-doped Si at the metal-insulator transition investigated by scanning tunnelling microscopy and electronic transport
The (111)-2 Ă 1 surface of in situ cleaved heavily P- or B-doped Si is investigated by scanning tunnelling microscopy and spectroscopy at room temperature and at low temperature. P atoms have been identified on different sites of the Si(111)-2 Ă 1 surface by their characteristic voltage-dependent contrast for positive as well as negative buckling of the Ï-bonded chains. The distributions of dopants per surface area and of nearest-neighbour distances are found to be in agreement with a random arrangement of dopants in Si up to doping levels well above the metalâinsulator transition. In addition, P atoms have been identified by their depth-dependent contrast down to the third layer beneath the surface with a volume density in agreement with the bulk doping density. The random electronic disorder supports the view of an Anderson transition driven by disorder close to the critical concentration or critical uniaxial stress
Magnetic behavior of single crystalline HoPdSi
The magnetic behavior of single-crystal HoPdSi, crystallizing in an
AlB-derived hexagonal structure, is investigated by magnetic susceptibility
() and electrical resistivity () measurements along two directions.
There is no dramatic anisotropy in the high temperature Curie-Weiss parameter
or in the and isothermal magnetization data, though there is a
noticeable anisotropy in the magnitude of between two perpendicular
orientations. The degree of anisotropy is overall less prominent than in the Gd
(which is an S-state ion!) and Tb analogues. A point of emphasis is that this
compound undergoes long range magnetic ordering below 8 K as in the case of
analogous Gd and Dy compounds. Considering this fact for these compounds with
well-localised f-orbital, the spin glass freezing noted for isomorphous U
compounds in the recent literature could be attributed to the role of the
f-ligand hybridization, rather than just Pd-Si disorder.Comment: Physical Review B, in pres
Entwicklung, Erprobung, Umsetzung und Evaluation von Strategien in den Bereichen Tiergesundheit, Haltung, FĂŒtterung, Management in der ökologischen Ferkelerzeugung
Die ökologische Ferkelerzeugung weist hinsichtlich Tiergesundheit, LeistungsfĂ€higkeit und Wirtschaftlichkeit groĂe Defizite auf. Die Ursachen sind komplex und betreffen u.a. FĂŒtterung, Haltung und Hygiene. FĂŒr diese Bereiche sollten durch Exakt- und Praxisversuche LösungsansĂ€tze entwickelt werden. Teilprojekte umfassten folgende Themen: Der Einfluss unterschiedlicher Raufutter in der FĂŒtterung tragender Sauen, die Wirkung einer Inulinzugabe sowie vom Extrudieren von Ackerbohnen in Sauen- und Ferkelfutter, die Bewertung alternativer Desinfektionsverfahren, ein Vergleich von Einzelhaltung versus kombinierte Einzel- und Gruppenhaltung sĂ€ugender Sauen sowie die Optimierung des Ferkelliegebereichs in der Ferkelaufzucht.
Zentrale Ergebnisse:
- Die verschiedenen Raufuttervarianten (Kleegrassilage, Heu, Maissilage, Topinamburknollen) hatten keine negativen Effekte auf Körperkonstitution und Reproduktionsleistungen der Sauen.
- Die Saugferkel der mit Inulin versorgten Sauen entwickelten sich gegenĂŒber der Kontrollgruppe wĂ€hrend der SĂ€ugezeit leistungsmĂ€Ăig besser, wĂ€hrend der Ferkelaufzucht gab es keine Leistungssteigerungen. Der Einsatz von getoasteten Ackerbohnen fĂŒhrte zu signifikant besseren Ferkelzunahmen gegenĂŒber dem Einsatz von extrudierten Ackerbohnen.
- Keines der getesteten alternativen Desinfektionsverfahren (HeiĂwasserdampf, elektroaktiviertes Wasser, Abflammen) ist eine Alternative zur chemischen Desinfektion bezĂŒglich Keimreduktion, Arbeitsaufwand und Kosten.
- GruppensĂ€ugen fĂŒhrt bei Sauen zu erhöhter AktivitĂ€t sowie zu spezifischen Verhaltensanpassungen. LeistungseinbuĂen konnten weder fĂŒr Sauen noch fĂŒr Ferkel dokumentiert werden. âGruppensĂ€ugenâ fĂŒhrt zu einem höheren Arbeitszeitbedarf und steigenden Baukosten.
- Der Liegebereich fĂŒr Aufzuchtferkel ist in vielen Betrieben nicht optimal und durch z. T. einfache MaĂnahmen (Abdichten des Liegenestes, WĂ€rmedĂ€mmung des Bodens, Bodenheizung, Anbringen einer weiteren WĂ€rmequelle) fĂŒr die Tiere zu verbessern
Pulmonary ORMDL3 is critical for induction of Alternaria -induced allergic airways disease
Genome-wide association studies have identified the ORM (yeast)-like protein isoform 3 (ORMDL3) gene locus on human chromosome 17q to be a highly significant risk factor for childhood-onset asthma.
Objective
We sought to investigate in vivo the functional role of ORMDL3 in disease inception.
Methods
An Ormdl3-deficient mouse was generated and the role of ORMDL3 in the generation of allergic airways disease to the fungal aeroallergen Alternaria alternata was determined. An adeno-associated viral vector was also used to reconstitute ORMDL3 expression in airway epithelial cells of Ormdl3 knockout mice.
Results
Ormdl3 knockout mice were found to be protected from developing allergic airways disease and showed a marked decrease in pathophysiology, including lung function and airway eosinophilia induced by Alternaria. Alternaria is a potent inducer of cellular stress and the unfolded protein response, and ORMDL3 was found to play a critical role in driving the activating transcription factor 6âmediated arm of this response through Xbp1 and downstream activation of the endoplasmic reticulumâassociated degradation pathway. In addition, ORMDL3 mediated uric acid release, another marker of cellular stress. In the knockout mice, reconstitution of Ormdl3 transcript levels specifically in the bronchial epithelium resulted in reinstatement of susceptibility to fungal allergenâinduced allergic airways disease.
Conclusions
This study demonstrates that ORMDL3, an asthma susceptibility gene identified by genome-wide association studies, contributes to key pathways that promote changes in airway physiology during allergic immune responses
Platinum Group Metal-Doped Tungsten Phosphates for Selective C-H Activation of Lower Alkanes
Platinum group metal (PGM)-based catalysts are known to be highly active in the total combustion of lower hydrocarbons. However, through an alternative catalyst design reported in this paper by isolating PGM-based active sites in a tungsten phosphate matrix, we present a class of catalysts for selective oxidation of n-butane, propane, and propylene that do not contain Mo or V as redox-active elements. Two different catalyst concepts have been pursued. Concept A: isolating Ru-based active sites in a tungsten phosphate matrix coming upon as ReO3-type structure. Concept B: dilution of PGM-based active sites through the synthesis of X-ray amorphous Ru tungsten phosphates supported on SiO2. Using a high-throughput screening approach, model catalysts over a wide compositional range were evaluated for C3 and C4 partial oxidation. Bulk crystalline and supported XRD amorphous phases with similar Ru/W/P compositions showed comparable performance. Hence, for these materials, composition is more crucial than the degree of crystallinity. Further studies for optimization on second-generation supported systems revealed even better results. High selectivity for n-butane oxidation to maleic anhydride and propane oxidation to an acrolein/acrylic acid has been achieved
Magnetic anomalies in single crystalline Tb5Si3
The polycrystalline form of the compound, Tb5Si3, crystallizing in
Mn5Si3-type hexagonal structure, which was earlier believe to order
antiferromagnetically below 69 K, has been recently reported by us to exhibit
interesting magnetoresistance (MR) anomalies. In order to understand the
magnetic anomalies of this compound better, we synthesized single crystals of
this compound and subjected them to intense magnetization and MR studies. The
results reveal that the magnetic behavior is strongly anisotropic as the easy
axis is along a basal plane. There appear to be multiple magnetic features in
the close vicinity of 70 K. In addition, there are multiple steps in isothermal
magnetization (which could not be resolved in the data for polycrystalline
data) for magnetic-field (H) along a basal plane. The sign of MR is positive in
the magnetically ordered state, and, interestingly, the magnitude dramatically
increases at the initial step for H parallel to basal plane, but decreases at
subsequent steps as though the origin of these steps are different. However,
for the perpendicular orientation (H || [0 0 0 1]), there is no evidence for
any step either in M(H) or in MR(H). These results establish this compound is
an interesting magnetic material
Scope and Impact of International Research in Human Pluripotent Stem Cells
In a recent study published in this journal it was claimed that the rate of publications from US-based authors in the human embryonic stem cell (hESC) research field was slowing or even declining from 2008 to 2010. It was assumed that this is the result of long-term effects of the Bush administrationâs funding policy for hESC research and the uncertain policy environment of recent years. In the present study, we analyzed a pool of more than 1,700 original hESC research papers published world-wide from 2007 to 2011. In contrast to the previous study, our results do not support the hypothesis of a decline in the productivity of US-based research but rather confirm a nearly unchanged leading position of US research in the hESC field with respect to both publication numbers and impact of research. Moreover, we analyzed about 500 papers reporting original research involving human induced pluripotent stem cells (hiPSCs) published through 2011 and found a dominant position of US research in this research field as well. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s12015-012-9409-0) contains supplementary material, which is available to authorized users
MEDBERT.de: A Comprehensive German BERT Model for the Medical Domain
This paper presents medBERTde, a pre-trained German BERT model specifically
designed for the German medical domain. The model has been trained on a large
corpus of 4.7 Million German medical documents and has been shown to achieve
new state-of-the-art performance on eight different medical benchmarks covering
a wide range of disciplines and medical document types. In addition to
evaluating the overall performance of the model, this paper also conducts a
more in-depth analysis of its capabilities. We investigate the impact of data
deduplication on the model's performance, as well as the potential benefits of
using more efficient tokenization methods. Our results indicate that
domain-specific models such as medBERTde are particularly useful for longer
texts, and that deduplication of training data does not necessarily lead to
improved performance. Furthermore, we found that efficient tokenization plays
only a minor role in improving model performance, and attribute most of the
improved performance to the large amount of training data. To encourage further
research, the pre-trained model weights and new benchmarks based on
radiological data are made publicly available for use by the scientific
community.Comment: Keno K. Bressem and Jens-Michalis Papaioannou and Paul Grundmann
contributed equall
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