1,189 research outputs found
Perforations in jet engine supersonic inlet increase shock stability
Modification of a conventional jet engine internal compression supersonic inlet results in increased shock stability and thus, engine instantaneous response to changes in inlet air properties. This technique provides a large amount of bleed near the maximum pressure recovery at the expense of minor bleed flow during critical operation
Gibt es geeignete Legehybriden fĂŒr die Ăko-Haltung?
In einem Feldversuch wurden Eignungs- und Leistungstests an verschiedenen Legehybriden-HerkĂŒnften durchgefĂŒhrt.
Wegen verstĂ€rkt auftretendem Federpicken bei ihren Legehennen initiierten schleswig-holsteinische Bio-Betriebe und der Ăkoring Schleswig Holstein mit UnterstĂŒtzung der Erna-Graff-Stiftung fĂŒr Tierschutz Berlin einen Eignungstest fĂŒr verschiedene Legehennen-HerkĂŒnfte, um eine fĂŒr den ökologischen Landbau geeignete Legehenne zu finden. Die Erfassung von GefiederschĂ€den, EiqualitĂ€t und die Ergebnisauswertung wurden in Zusammenarbeit mit dem HDLGN Tierzuchtzentrum Neu-Ulrichstein durchgefĂŒhrt
Evidence for Cooper Pair Diffraction on the Vortex Lattice of Superconducting Niobium
We investigated the Abrikosov vortex lattice (VL) of a pure Niobium single
crystal with the muon spin rotation (\mu SR) technique. Analysis of the \mu SR
data in the framework of the BCS-Gor'kov theory allowed us to determine
microscopic parameters and the limitations of the theory. With decreasing
temperature the field variation around the vortex cores deviates substantially
from the predictions of the Ginzburg-Landau theory and adopts a pronounced
conical shape. This is evidence of partial diffraction of Cooper pairs on the
VL predicted by Delrieu for clean superconductors.Comment: 9 pages, 6 figure
Magnetic field distribution and characteristic fields of the vortex lattice for a clean superconducting niobium sample in an external field applied along a three-fold axis
The field distribution in the vortex lattice of a pure niobium single crystal
with an external field applied along a three-fold axis has been investigated by
the transverse-field muon-spin-rotation (TF-SR) technique over a wide
range of temperatures and fields. The experimental data have been analyzed with
the Delrieu's solution for the form factor supplemented by phenomenological
formulas for the parameters. This has enabled us to experimentally establish
the temperatures and fields for the Delrieu's, Ginzburg-Landau's, and Klein's
regions of the vortex lattice. Using the numerical solution of the
quasiclassical Eilenberger's equation the experimental results have been
reasonably understood. They should apply to all clean BCS superconductors. The
analytical Delrieu's model supplemented by phenomenological formulas for its
parameters is found to be reliable for analyzing TF-SR experimental data
for a substantial part of the mixed phase. The Abrikosov's limit is contained
in it.Comment: 12 pages, 15 figure
Isotope effects on the dynamics of amorphous ices and aqueous phosphoric acid solutions
The glass transitions of amorphous ices as well as of aqueous phosphoric acid solutions were reported to display very large 1H/2H isotope effects. Using dielectric spectroscopy, in both types of glassformers for equimolar protonated/deuterated mixtures an almost ideal isotope-mixing behavior rather than a bimodal relaxation is found. For the amorphous ices this finding is interpreted in terms of a glass-to-liquid rather than an orientational glass transition scenario. Based on calorimetric results revealing that major 16O/18O isotope effects are missing, the latter scenario was previously favored for the amorphous ices. Considering the dielectric results on 18O substituted amorphous ices and by comparison with corresponding results for the aqueous phosphoric acid solutions, it is argued that the present findings are compatible with the glass-to-liquid scenario. To provide additional information regarding the deeply supercooled state of 1H/2H isotopically mixed and 18O substituted glassformers, the aqueous phosphoric acid solutions are studied using shear mechanical spectroscopy as well, a technique which so far could not successfully be applied to characterize the glass transitions of the amorphous ices
Controlled assembly of SNAP-PNA-fluorophore systems on DNA templates to produce fluorescence resonance energy transfer
The SNAP protein is a widely used self-labeling tag that can be used for tracking protein localization and trafficking in living systems. A model system providing controlled alignment of SNAP-tag units can provide a new way to study clustering of fusion proteins. In this work, fluorescent SNAP-PNA conjugates were controllably assembled on DNA frameworks forming dimers, trimers, and tetramers. Modification of peptide nucleic acid (PNA) with the O6-benzyl guanine (BG) group allowed the generation of site-selective covalent links between PNA and the SNAP protein. The modified BG-PNAs were labeled with fluorescent Atto dyes and subsequently chemo-selectively conjugated to SNAP protein. Efficient assembly into dimer and oligomer forms was verified via size exclusion chromatography (SEC), electrophoresis (SDS-PAGE), and fluorescence spectroscopy. DNA directed assembly of homo- and hetero-dimers of SNAP-PNA constructs induced homo- and hetero-FRET, respectively. Longer DNA scaffolds controllably aligned similar fluorescent SNAP-PNA constructs into higher oligomers exhibiting homo-FRET. The combined SEC and homo-FRET studies indicated the 1:1 and saturated assemblies of SNAP-PNA-fluorophore:DNA formed preferentially in this system. This suggested a kinetic/stoichiometric model of assembly rather than binomially distributed products. These BG-PNA-fluorophore building blocks allow facile introduction of fluorophores and/or assembly directing moieties onto any protein containing SNAP. Template directed assembly of PNA modified SNAP proteins may be used to investigate clustering behavior both with and without fluorescent labels which may find use in the study of assembly processes in cells
Experimental Determination of the Characteristics of a Positron Source Using Channeling
Numerical simulations and `proof of principle' experiments showed clearly the
interest of using crystals as photon generators dedicated to intense positron
sources for linear colliders. An experimental investigation, using a 10 GeV
secondary electron beam, of the SPS-CERN, impinging on an axially oriented
thick tungsten crystal, has been prepared and operated between May and August
2000. After a short recall on the main features of positron sources using
channeling in oriented crystals, the experimental set-up is described. A
particular emphasis is put on the positron detector made of a drift chamber,
partially immersed in a magnetic field. The enhancement in photon and positron
production in the aligned crystal have been observed in the energy range 5 to
40 GeV, for the incident electrons, in crystals of 4 and 8 mm as in an hybrid
target. The first results concerning this experiment are presented hereafter.Comment: 3 pages, 6 figures, submitted to Linac200
Random Tilings: Concepts and Examples
We introduce a concept for random tilings which, comprising the conventional
one, is also applicable to tiling ensembles without height representation. In
particular, we focus on the random tiling entropy as a function of the tile
densities. In this context, and under rather mild assumptions, we prove a
generalization of the first random tiling hypothesis which connects the maximum
of the entropy with the symmetry of the ensemble. Explicit examples are
obtained through the re-interpretation of several exactly solvable models. This
also leads to a counterexample to the analogue of the second random tiling
hypothesis about the form of the entropy function near its maximum.Comment: 32 pages, 42 eps-figures, Latex2e updated version, minor grammatical
change
Phase III randomised trial comparing paclitaxel/carboplatin with paclitaxel/cisplatin in patients with advanced non-small-cell lung cancer: a cooperative multinational trial
Background: The combination of paclitaxel with cisplatin or carboplatin has significant activity in non-small-cell lung cancer (NSCLC). This phase III study of chemotherapy-naĂŻve advanced NSCLC patients was designed to assess whether response rate in patients receiving a paclitaxel/carboplatin combination was similar to that in patients receiving a paclitaxel/cisplatin combination. Paclitaxel was given at a dose of 200 mg/m2 (3-h intravenous infusion) followed by either carboplatin at an AUC of 6 or cisplatin at a dose of 80 mg/m2, all repeated every 3 weeks. Survival, toxicity and quality of life were also compared. Patients and methods: Patients were randomised to receive one of the two combinations, stratified according to centre, performance status, disease stage and histology. The primary analyses of response rate and survival were carried out on response-evaluable patients. Survival was also analysed for all randomised patients. Toxicity analyses were carried out on all treated patients. Results: A total of 618 patients were randomised. The two treatment arms were well balanced with regard to gender (83% male), age (median 58 years), performance status (83% ECOG 0-1), stage (68% IV, 32% IIIB) and histology (38% squamous cell carcinoma). In the paclitaxel/carboplatin arm, 306 patients received a total of 1311 courses (median four courses, range 1-10 courses) while in the paclitaxel/cisplatin arm, 302 patients received a total of 1321 courses (median four courses, range 1-10 courses). In only 76% of courses, carboplatin was administered as planned at an AUC of 6, while in 96% of courses, cisplatin was given at the planned dose of 80 mg/m2. The response rate was 25% (70 of 279) in the paclitaxel/carboplatin arm and 28% (80 of 284) in the paclitaxel/cisplatin arm (P = 0.45). Responses were reviewed by an independent radiological committee. For all randomised patients, median survival was 8.5 months in the paclitaxel/carboplatin arm and 9.8 months in the paclitaxel/cisplatin arm [hazard ratio 1.20, 90% confidence interval (CI) 1.03-1.40]; the 1-year survival rates were 33% and 38%, respectively. On the same dataset, a survival update after 22 months of additional follow-up yielded a median survival of 8.2 months in the paclitaxel/carboplatin arm and 9.8 months in the paclitaxel/cisplatin arm (hazard ratio 1.22, 90% CI 1.06-1.40; P = 0.019); the 2-year survival rates were 9% and 15%, respectively. Excluding neutropenia and thrombocytopenia, which were more frequent in the paclitaxel/carboplatin arm, and nausea/vomiting and nephrotoxicity, which were more frequent in the paclitaxel/cisplatin arm, the rate of severe toxicities was generally low and comparable between the two arms. Overall quality of life (EORTC QLQ-C30 and LC-13) was also similar between the two arms. Conclusions: This is the first trial comparing carboplatin and cisplatin in the treatment of advanced NSCLC. Although paclitaxel/carboplatin yielded a similar response rate, the significantly longer median survival obtained with paclitaxel/cisplatin indicates that cisplatin-based chemotherapy should be the first treatment optio
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