1,257 research outputs found
Bridging length and time scales in sheared demixing systems: from the Cahn-Hilliard to the Doi-Ohta model
We develop a systematic coarse-graining procedure which establishes the
connection between models of mixtures of immiscible fluids at different length
and time scales. We start from the Cahn-Hilliard model of spinodal
decomposition in a binary fluid mixture under flow from which we derive the
coarse-grained description. The crucial step in this procedure is to identify
the relevant coarse-grained variables and find the appropriate mapping which
expresses them in terms of the more microscopic variables. In order to capture
the physics of the Doi-Ohta level, we introduce the interfacial width as an
additional variable at that level. In this way, we account for the stretching
of the interface under flow and derive analytically the convective behavior of
the relevant coarse-grained variables, which in the long wavelength limit
recovers the familiar phenomenological Doi-Ohta model. In addition, we obtain
the expression for the interfacial tension in terms of the Cahn-Hilliard
parameters as a direct result of the developed coarse-graining procedure.
Finally, by analyzing the numerical results obtained from the simulations on
the Cahn-Hilliard level, we discuss that dissipative processes at the Doi-Ohta
level are of the same origin as in the Cahn-Hilliard model. The way to estimate
the interface relaxation times of the Doi-Ohta model from the underlying
morphology dynamics simulated at the Cahn-Hilliard level is established.Comment: 29 pages, 2 figures, accepted for publication in Phys. Rev.
Supersymmetry solution for finitely extensible dumbbell model
Exact relaxation times and eigenfunctions for a simple mechanical model of
polymer dynamics are obtained using supersymmetry methods of quantum mechanics.
The model includes the finite extensibility of the molecule and does not make
use of the self-consistently averaging approximation. The finite extensibility
reduces the relaxation times when compared to a linear force. The linear
viscoelastic behaviour is obtained in the form of the ``generalized Maxwell
model''. Using these results, a numerical integration scheme is proposed in the
presence of a given flow kinematics.Comment: 5 pages, 2 figure
Amidoschwarz10B in der forensischen Spurenuntersuchung: Vergleichende Untersuchungen an forensischem Spurenmaterial
Zusammenfassung: Blutspuren gehören zu den aussagekräftigsten Spuren in der forensischen Fallanalyse. Einerseits kann die Beurteilung von Aussehen, Menge, Form und Verteilung an Tatorten Hinweise auf den Tathergang geben. Andererseits lassen sich heute auch aus kleinsten Blutmengen zumeist vollständige DNA-Profile erstellen, die dann ebenfalls eine Rekonstruktion des Tatablaufs und über die molekulargenetische DNA-Analyse Aussagen zur Tatbeteiligung von Personen ermöglichen. In der vorgestellten Studie wurden Vollblutproben auf unterschiedliche Spurenträger aufgebracht und mithilfe des Hexagon OBTI® auf das Vorhandensein von Blut hin untersucht. Nach Inkubation mit 2 verschiedenen Zubereitungen von Amidoschwarz10B konnte gezeigt werden, dass dessen Einsatz zu starken Beeinträchtigungen bzw. falsch-negativen Ergebnissen des OBTI führen kann. Ein negativer Einfluss von Amidoschwarz10B auf das Probenmaterial war hingegen bei den nachfolgend durchgeführten DNA-Analysen nicht festzustelle
Drought-stressed, irrigated, and additive-treated corn silages for growing cattle
Cattle fed drought-stressed corn silage gained about 10% slower but were just as efficient as cattle fed irrigated corn silage. Because the irrigated corn out yielded the drought corn (17.4 VS. 8.2 tons per acre), the irrigated silage gave a much higher cattle gain per acre (1928 VS. 940 1b). Silo Guard II®-treated silage had an advantage in DM recovery and feed conversion over its control and produced 4.6 more pounds of cattle gain per ton of crop ensiled. Cattle fed H/M Inoculant®- treated silage gained significantly faster than cattle fed the control, however, the treated silage gave only slight improvements in DM recovery and gain per ton of crop ensiled
Fluctuation relations and coarse-graining
We consider the application of fluctuation relations to the dynamics of
coarse-grained systems, as might arise in a hypothetical experiment in which a
system is monitored with a low-resolution measuring apparatus. We analyze a
stochastic, Markovian jump process with a specific structure that lends itself
naturally to coarse-graining. A perturbative analysis yields a reduced
stochastic jump process that approximates the coarse-grained dynamics of the
original system. This leads to a non-trivial fluctuation relation that is
approximately satisfied by the coarse-grained dynamics. We illustrate our
results by computing the large deviations of a particular stochastic jump
process. Our results highlight the possibility that observed deviations from
fluctuation relations might be due to the presence of unobserved degrees of
freedom.Comment: 19 pages, 6 figures, very minor change
Effective temperatures in a simple model of non-equilibrium, non-Markovian dynamics
The concept of effective temperatures in nonequilibrium systems is studied
within an exactly solvable model of non-Markovian diffusion. The system is
coupled to two heat baths which are kept at different temperatures: one
('fast') bath associated with an uncorrelated Gaussian noise and a second
('slow') bath with an exponential memory kernel. Various definitions of
effective temperatures proposed in the literature are evaluated and compared.
The range of validity of these definitions is discussed. It is shown in
particular, that the effective temperature defined from the
fluctuation-dissipation relation mirrors the temperature of the slow bath in
parameter regions corresponding to a separation of time scales. On the
contrary, quasi-static and thermodynamic definitions of an effective
temperature are found to display the temperature of the fast bath in most
parameter regions
Search for excited τ-leptons and leptoquarks in the final state with τ-leptons and jets in pp collisions at √s = 13 TeV
A search is reported for excited τ-leptons and leptoquarks in events with two hadronically decaying τ-leptons and two or more jets. The search uses proton-proton (pp) collision data at √s = 13 TeV recorded by the ATLAS experiment during the Run 2 of the Large Hadron Collider in 2015–2018. The total integrated luminosity is 139 fb−1. The excited τ-lepton is assumed to be produced and to decay via a four-fermion contact interaction into an ordinary τ-lepton and a quark-antiquark pair. The leptoquarks are assumed to be produced in pairs via the strong interaction, and each leptoquark is assumed to couple to a charm or lighter quark and a τ-lepton. No excess over the background prediction is observed. Excited τ-leptons with masses below 2.8 TeV are excluded at 95% CL in scenarios with the contact interaction scale Λ set to 10 TeV. At the extreme limit of model validity where Λ is set equal to the excited τ-lepton mass, excited τ-leptons with masses below 4.6 TeV are excluded. Leptoquarks with masses below 1.3 TeV are excluded at 95% CL if their branching ratio to a charm quark and a τ-lepton equals 1. The analysis does not exploit flavour-tagging in the signal region
Validation of non-REM sleep stage decoding from resting state fMRI using linear support vector machines
A growing body of literature suggests that changes in consciousness are reflected in specific connectivity patterns of the brain as obtained from resting state fMRI (rs-fMRI). As simultaneous electroencephalography (EEG) is often unavailable, decoding of potentially confounding sleep patterns from rs-fMRI itself might be useful and improve data interpretation. Linear support vector machine classifiers were trained on combined rs-fMRI/EEG recordings from 25 subjects to separate wakefulness (S0) from non-rapid eye movement (NREM) sleep stages 1 (S1), 2 (S2), slow wave sleep (SW) and all three sleep stages combined (SX). Classifier performance was quantified by a leave-one-subject-out cross-validation (LOSO-CV) and on an independent validation dataset comprising 19 subjects. Results demonstrated excellent performance with areas under the receiver operating characteristics curve (AUCs) close to 1.0 for the discrimination of sleep from wakefulness (S0|SX), S0|S1, S0|S2 and S0|SW, and good to excellent performance for the classification between sleep stages (S1|S2:~0.9; S1|SW:~1.0; S2|SW:~0.8). Application windows of fMRI data from about 70 s were found as minimum to provide reliable classifications. Discrimination patterns pointed to subcortical-cortical connectivity and within-occipital lobe reorganization of connectivity as strongest carriers of discriminative information. In conclusion, we report that functional connectivity analysis allows valid classification of NREM sleep stages
Searches for lepton-flavour-violating decays of the Higgs boson into eτ and μτ in √s=13 TeV pp collisions with the ATLAS detector
This paper presents direct searches for lepton flavour violation in Higgs boson decays, H → eτ and H → μτ, performed using data collected with the ATLAS detector at the LHC. The searches are based on a data sample of proton-proton collisions at a centre-of-mass energy √s = 13 TeV, corresponding to an integrated luminosity of 138 fb−1. Leptonic (τ → ℓνℓντ) and hadronic (τ → hadrons ντ) decays of the τ-lepton are considered. Two background estimation techniques are employed: the MC-template method, based on data-corrected simulation samples, and the Symmetry method, based on exploiting the symmetry between electrons and muons in the Standard Model backgrounds. No significant excess of events is observed and the results are interpreted as upper limits on lepton-flavour-violating branching ratios of the Higgs boson. The observed (expected) upper limits set on the branching ratios at 95% confidence level, β(H → eτ) < 0.20% β(0.12%) and (H → μτ ) < 0.18% (0.09%), are obtained with the MC-template method from a simultaneous measurement of potential H → eτ and H → μτ signals. The best-fit branching ratio difference, β(H → μτ) → β(H → eτ), measured with the Symmetry method in the channel where the τ-lepton decays to leptons, is (0.25 ± 0.10)%, compatible with a value of zero within 2.5σ
Carrier capture and relaxation in Stranski-Krastanow InxGa1-xAs/GaAs(311)B quantum dots
We have investigated the structure and optical properties of In0.6Ga0.4As/GaAs(311)B quantum dots (QD's) formed by the Stranski-Krastanow growth mode during metal-organic chemical-vapor deposition. We find that (311)B QD structures display a higher energy QD luminescence emission and a stronger wetting-layer emission than (100) QD's of similar diameter and density. Temperature-dependent photoluminescence (PL) measurements reveal shallow QD confinement energies and strong interaction between neighboring quantum dots. Longer PL rise times of the ground-state emission of (311)B QD's compared to (100) QD's are ascribed to the effect of differing numbers, energies, and level spacings of QD confined states on intersublevel relaxation mechanisms at low-carrier excitation densities
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