Search results for "SCA"
showing 10 items of 23299 documents
Development of core-shell colloids to study self-diffusion in highly concentrated dispersions
2007
To study single particle motion in highly concentrated colloidal dispersions, a host-tracer colloid system was developed, consisting of crosslinked polymer micronetwork spheres placed in a good solvent. The host colloid is made invisible to the experimental probe by matching its refractive index to that of the solvent. For the tracer particles a core-shell structure was chosen to ensure the interaction potential to be identical to that of the host particles. Therefore the shell was made of the same polymer as the host. The core differs in refractive index from the solvent and is therefore visible due to scattered light.
Resolving the Fundamentals of Magnetotransport in Metals with Ultrafast Terahertz Spectroscopy
2016
Using terahertz spectroscopy we directly resolved the fundamentals of spin-dependent conductivity in ferromagnetic metals. We quantified the differences in conduction by Fermi-level electrons with opposite spins on the sub-100 fs timescale of electron momentum scattering.
Analysis of static friction and elastic forces in a nanowire bent on a flat surface: A comparative study
2014
ZnO nanowires bent to a complex shape and held in place by static friction force from supporting flat surface are investigated experimentally and theoretically. The complex shapes are obtained by bending the nanowires inside a scanning electron microscope with a sharp tip attached to a nanopositioner. Several methods previously described in the literature are applied along with author's original method to calculate the distributed friction force and stored elastic energy in the nanowires from the bending profile. This comparative study evidences the importance of the usage of appropriate models for accurate analysis of the nanowires profile. It is demonstrated that incomplete models can lea…
Stopover strategies in birds: a review of methods for estimating stopover length
1999
This study categorizes and reviews methods used to estimate stopover length in migratory birds. Stopover length is an important variable in analysing migration strategies. The analysis of the stopover pattern of migratory birds typically attempts to investigate variability in the number of stopovers and in the length of time spent at stopover sites in relation to species, age, sex and body condition. Although the number of capture-recapture studies analysing stopover length has increased substantially, most are analysed using the simple last-first capture method which gives biased estimates. The use of mathematical models to calculate stopover length is uncommon. Most researchers assume hom…
Localized Motion in Supercooled Glycerol as Measured by 2 H-NMR Spin-Lattice Relaxation and Incoherent Neutron Scattering
1991
Selectively deuterated glycerol has been subjected to 2H-NMR spin-lattice relaxation and quasi-elastic neutron scattering experiments. The measurements yield relaxation rates and a non-Gaussian Q-dependence of the Debye-Waller factor which are different for the two hydrogen sites. The data analysis shows that below the onset of the glass transition α-process the hydrogens perform a local motion (≈ 10-12 s) in addition to what is expected from harmonic phonons. The resulting mean-square displacements are highly temperature dependent but are significantly smaller than those found in van der Waals glasses. Amplitudes and activation energies of the carbon-bonded and oxygen-bonded hydrogens are …
On the Multifractal Character of the Lorenz Attractor
1992
A detailed analysis of the Lorenz attractor in connection with generalized dimensions is presented in this work. Different methods have been employed to estimate these dimensions. Two of them are of standard type. A new method, based on the minimal spanning tree of the point distribution, is extensively tested in this work. It turns out that the Lorenz attractor is very appropriate for being analyzed through this technique, which produces a very clean estimate of the extrema scaling indices α min and α max . The different methods give qualitatively the same result: The Lorenz attractor has a multifractal character
Search for a Standard Model Higgs Boson inWH→ℓvbb¯inpp¯Collisions ats=1.96 TeV
2009
We present a search for a standard model Higgs boson produced in association with a W boson using 2.7 fb(-1) of integrated luminosity of pp collision data taken at square root s = 1.96 TeV. Limits on the Higgs boson production rate are obtained for masses between 100 and 150 GeV/c(2). Through the use of multivariate techniques, the analysis achieves an observed (expected) 95% confidence level upper limit of 5.6 (4.8) times the theoretically expected production cross section for a standard model Higgs boson with a mass of 115 GeV/c(2).
Search for the Higgs Boson in theH→WW(*)→l+νl−ν¯Decay Channel inppCollisions ats=7 TeVwith the ATLAS Detector
2012
A search for the Higgs boson has been performed in the H -> WW(*()) -> l+vl-(v) over bar channel (l = e/mu) with an integrated luminosity of 2.05 fb(-1) of pp collisions at root s = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. No significant excess of events over the expected background is observed and limits on the Higgs boson production cross section are derived for a Higgs boson mass in the range 110 GeV< m(H) < 300 GeV. The observations exclude the presence of a standard model Higgs boson with a mass 145 < m(H) < 206 GeV at 95% confidence level.
Elastic properties, structures and phase transitions in model colloids
2004
The nature of the melting transition for a system of hard discs with translational degrees of freedom in two spatial dimensions has been analysed by a combination of computer simulation methods and a finite size scaling technique. The behaviour of the system is consistent with the predictions of the Kosterlitz–Thouless–Halperin–Nelson–Young (KTHNY) theory. The structural and elastic properties of binary colloidal mixtures in two and three spatial dimensions are discussed as well as those of colloidal systems with quenched point impurities. Hard and soft discs in external periodic (light-) fields show rich phase diagrams including freezing and melting transitions when the density of the syst…
Automatic generation of emissivity maps on a European scale
2009
The remote sensing measurement of the land surface temperature from satellites provides an overview of this magnitude on a continuous and regular basis. The study of its evolution in time and space is a critical factor in many scientific fields such as weather forecasting, detection of forest fires, climate change, and so on. The main problem of making this measurement from satellite data is the need to correct the effects of the atmosphere and the surface emissivity. In this work, these corrections have been made using a split-window algorithm. The aim was to define an enhanced vegetation cover method and develop a system that used it, in order to automatically generate maps of land surfac…