1,500 research outputs found
A leap forward in closing the marine carbon budget from observations
Dem Ozean fĂ€llt eine entscheidende Rolle in unserem Klimasystem zu: Er absorbiert gemittelt ĂŒber die letzten zehn Jahre etwa 23 Prozent der menschengemachten jĂ€hrlichen CO2-Emissionen. Neue, beobachtungsbasierte AbschĂ€tzungen mittels neuronaler Netzwerke deuten jedoch auf starke Schwankungen in der CO2-Aufnahme auf dekadischen Zeitskalen hin. Insbesondere das SĂŒdpolarmeer spielt dabei eine entscheidende Rolle.The ocean plays a crucial role in the global carbon cycle by absorbing the equivalent of 23 percent of all annual CO2 emissions, averaged over the past decade, created by human activities. New observation-based estimates, reconstructed using novel neural network methods, reveal however substantial vacillations in the CO2 uptake on interannual through decadal. The Southern Ocean plays a critical role in the observed fluctuations
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
A 6,000 Stormwater Pond Task: Meeting the Needs of Diverse Audiences for Stormwater Pond Management Outreach in the Berkeley, Charleston and Dorchester Communities
2014 S.C. Water Resources Conference - Informing Strategic Water Planning to Address Natural Resource, Community and Economic Challenge
Parton distribution functions and quark orbital motion
Covariant version of the quark-parton model is studied. Dependence of the
structure functions and parton distributions on the 3D quark intrinsic motion
is discussed. The important role of the quark orbital momentum, which is a
particular case of intrinsic motion, appears as a direct consequence of the
covariant description. Effect of orbital motion is substantial especially for
polarized structure functions. At the same time, the procedure for obtaining
the quark momentum distributions of polarized quarks from the combination of
polarized and unpolarized structure functions is suggested.Comment: 17 pages, 2 figures, 1 table. Paper is accepted for publication in
Eur.Phys.J.
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
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
First observation of the deflection of a 33 TeV Pb ion beam in a bent silicon crystal
For the first time, the deflection of an ultra-relativistic, fully stripped Pb82+ ion beam in a bent silicon crystal has been observed. The ions were provided by the CERN-SPS in the H4 beam at a momentum of 400 GeV/c per unit of charge. A 60 mm long silicon crystal, bent over 50 mm to give a 4 mrad deflection angle, was used in this experiment. The measured Pb ion deflection efficiency is comparable to the one obtained with protons at an equivalent ratio of momentum per charge, and is found to be about 15\% for a beam with a divergence of 35 microradians (FWHM). The interaction rate observed in a background counter is found to drop when the crystal is well aligned with the beam. This corroborates further the channeling model, which predicts that channeled ions are steered away from regions of high electron densities as well as the nuclei in the crystal
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
- âŠ