Search results for "Statistical fluctuations"
showing 10 items of 12 documents
Self-assembly of bioelastomeric structures from solutions: Mean-field critical behavior and Flory-Huggins free energy of interactions
1993
Elastic and quasi-elastic light scattering studies were performed on aqueous solutions of poly (Val-Pro-Gly-Gly), a representative synthetic bioelastomer that differs from the previously studied poly (Val-Pro-Gly-Val-Gly) by the deletion of the hydrophobic Val in position four. When the spinodal line was approached from the region of thermodynamic stability, the intensity of light scattered by fluctuations, and the related lifetime and correlation length, were observed to diverge with mean-field critical exponents for both systems. Fitting of the experimental data allowed determining the spinodal and binodal (coexistence) lines that characterize the phase diagrams of the two systems, and it…
Capillary Waves in a Colloid-Polymer Interface
2004
The structure and the statistical fluctuations of interfaces between coexisting phases in the Asakura-Oosawa (AO) model for a colloid--polymer mixture are analyzed by extensive Monte Carlo simulations. We make use of a recently developed grand canonical cluster move with an additional constraint stabilizing the existence of two interfaces in the (rectangular) box that is simulated. Choosing very large systems, of size LxLxD with L=60 and D=120, measured in units of the colloid radius, the spectrum of capillary wave-type interfacial excitations is analyzed in detail. The local position of the interface is defined in terms of a (local) Gibbs surface concept. For small wavevectors capillary wa…
Role of statistical fluctuations in the emission ofδelectrons from dissipative heavy-ion collisions
1990
Energy spectra of {delta} electrons emitted in coincidence with deep-inelastic heavy-ion collisions are calculated within a Langevin Monte Carlo description using the surface-friction model. We investigate the effects that wipe out the originally expected oscillatory pattern of the spectra. Emphasis is placed on the role of statistical fluctuations in extracting interaction time distributions of deep-inelastic collisions from the measured {delta}-electron spectra. The calculations are compared to data for U+Au at 8.65 MeV/nucleon.
Spatial multifractal properties of wave packets in the Anderson model of localization.
1993
The multifractal properties of electronic wave functions in disordered samples are investigated. In a given energy range all eigenstates are determined for the same disorder configuration in the Anderson model of localization. It is shown that the singularity spectrum and the generalized dimensions change only slowly with energy, aside from statistical fluctuations. More important, the wave packet constructed by linear combination of the eigenstates shows quantitatively the same multifractal properties. Consequences for the transport properties of electronic states in disordered systems are discussed.
SU-FF-T-15: Comparison of Various Monte Carlo Codes for Brachytherapy Source Dosimetry
2009
Purpose: Monte Carlo simulations are used for dosimetric evaluation of brachytherapysources. Various investigators had demonstrated good agreement between the measured and simulated data while some others have shown discrepancies between the two methods. These discrepancies were attributed to the errors in cross section data, differences in phantom and source geometry and composition. However, the exact causes of these differences have not yet fully explored. The goal of this project is to verify the differences among the widely available Monte Carlo codes for brachytherapysourcedosimetry.Material and method: These investigations are based on VariSource 192 Ir , Model VS2000, IsoAid Advanta…
Über eine bestimmung der peaklage von reinen und komplexen photopeaks
1966
Abstract To determine the center of photopeaks normally occuring in γ-spectra in complex form, some modified methods are developed for most typical cases: a. single peak and constant background; b. single peak and exponentially decreasing background; c. two overlapping peaks at different distances of energy and varying peak intensities. The statistical fluctuations can be widely eliminated by use of a simple averaging method, so that peak center locations can be evaluated even in the case of relatively small peak intensities. Applying the methods proposed to some cases of strongly overlapping photopeaks, excellent agreement between the theoretical and experimentally obtained values could be…
Double-seed stabilization of a continuum generated from fourth-order modulation instability
2013
Summary form only given. Modulation instability (MI) is a ubiquitous process in which a weak field is exponentially amplified through a balance between dispersive and nonlinear effects. In single-mode scalar optical fibers, the positive Kerr nonlinearity phase-mismatch can be compensated by anomalous second-order dispersion, a process known as MI2. But phase-matched solutions can also exist in normal second-order dispersion region, thanks to negative even higher-order terms [1]. This process, that we label MI4, gives rise to a pair of narrow sidebands widely detuned far from the pump. MI may grow spontaneously from broadband noise and is usually the main process involved in the early stages…
A method for fitting multi-component decay curves
1982
Abstract A generalization of a non-iterative method recently proposed by Mukoyama for the fitting of two-component decay curve is presented. Two modifications of the procedure are also suggested, by which the influence of the statistical fluctuations of the data may be reduced. Results of fairly good quality are obtained also for three- and, to a lesser extent, for four-component decay curves.
Low-energy couplings of QCD from current correlators near the chiral limit
2004
We investigate a new numerical procedure to compute fermionic correlation functions at very small quark masses. Large statistical fluctuations, due to the presence of local ``bumps'' in the wave functions associated with the low-lying eigenmodes of the Dirac operator, are reduced by an exact low-mode averaging. To demonstrate the feasibility of the technique, we compute the two-point correlator of the left-handed vector current with Neuberger fermions in the quenched approximation, for lattices with a linear extent of L~1.5 fm, a lattice spacing a~0.09 fm, and quark masses down to the epsilon-regime. By matching the results with the corresponding (quenched) chiral perturbation theory expres…
Lysozyme crystallization rates controlled by anomalous fluctuations
2005
Abstract Nucleation of protein aggregates and crystals is a process activated by statistical fluctuations of concentration. Nucleation rates may change by several orders of magnitude upon apparently minor changes in the multidimensional space of parameters (temperature, pH, protein concentration, salt type and concentrations, additives). We use available data on hen egg lysozyme crystal induction times in different solution conditions. We measure by static and dynamic light scattering the amplitudes and lifetimes of anomalously ample and long-lived fluctuations occurring in proximity of the liquid–liquid demixing region of the given lysozyme solutions. This allows determining the related sp…