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Your search keyword '"Welling, M. S."' showing total 22 results
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22 results on '"Welling, M. S."'

1. Dynamic roughening of the magnetic flux landscape in YBa$_2$Cu$_3$O$_{7-x}$

Author

Aegerter, C. M., Welling, M. S., and Wijngaarden, R. J.

Subjects
Condensed Matter - Statistical Mechanics, Condensed Matter - Superconductivity
Abstract

We study the magnetic flux landscape in YBa$_2$Cu$_3$O$_{7-x}$ thin films as a two dimensional rough surface. The vortex density in the superconductor forms a self-affine structure in both space and time. This is characterized by a roughness exponent $\alpha = 0.76(3)$ and a growth exponent $\beta = 0.57(6)$. This is due to the structure and distribution of flux avalanches in the self-organized critical state, which is formed in the superconductor. We also discuss our results in the context of other roughening systems in the presence of quenched disorder., Comment: 13 pages, 7 figures, accepted for publication in Physica A

Published
2004
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2. Self-organized criticality induced by quenched disorder: experiments on flux avalanches in NbH$_x$ films

Author

Welling, M. S., Aegerter, C. M., and Wijngaarden, R. J.

Subjects
Condensed Matter - Statistical Mechanics, Condensed Matter - Superconductivity
Abstract

We present an experimental study of the influence of quenched disorder on the distribution of flux avalanches in type-II superconductors. In the presence of much quenched disorder, the avalanche sizes are power-law distributed and show finite size scaling, as expected from self-organized criticality (SOC). Furthermore, the shape of the avalanches is observed to be fractal. In the absence of quenched disorder, a preferred size of avalanches is observed and avalanches are smooth. These observations indicate that a certain minimum amount of disorder is necessary for SOC behavior. We relate these findings to the appearance or non-appearance of SOC in other experimental systems, particularly piles of sand., Comment: 4 pages, 4 figures

Published
2004
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3. Self-organized criticality in the Bean state in YBa$_2$Cu$_3$O$_{7-x}$ thin films

Author

Aegerter, C. M., Welling, M. S., and Wijngaarden, R. J.

Subjects
Condensed Matter - Soft Condensed Matter, Condensed Matter - Statistical Mechanics
Abstract

The penetration of magnetic flux into a thin film of YBa$_2$Cu$_3$O$_{7-x}$ is studied when the external field is ramped slowly. In this case the flux penetrates in bursts or avalanches. The size of these avalanches is distributed according to a power law with an exponent of $\tau$ = 1.29(2). The additional observation of finite-size scaling of the avalanche distributions, with an avalanche dimension D = 1.89(3), gives strong indications towards self-organized criticality in this system. Furthermore we determine exponents governing the roughening dynamics of the flux surface using some universal scaling relations. These exponents are compared to those obtained from a standard roughening analysis., Comment: 4 pages, 4 figures, submitted to PRL

Published
2003

8. Self-organized criticality in the Bean state in YBa2Cu3O7-x thin films

Author

Aegerter, C. M., Welling, M. S., Wijngaarden, R. J., and Photo Conversion Materials

Subjects
Statistical Mechanics (cond-mat.stat-mech), genetic structures, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Condensed Matter - Soft Condensed Matter, equipment and supplies, eye diseases, Physics::Fluid Dynamics, Condensed Matter::Soft Condensed Matter, Condensed Matter::Materials Science, Condensed Matter::Superconductivity, Soft Condensed Matter (cond-mat.soft), sense organs, human activities, Condensed Matter - Statistical Mechanics
Abstract

The penetration of magnetic flux into a thin film of YBa$_2$Cu$_3$O$_{7-x}$ is studied when the external field is ramped slowly. In this case the flux penetrates in bursts or avalanches. The size of these avalanches is distributed according to a power law with an exponent of $\tau$ = 1.29(2). The additional observation of finite-size scaling of the avalanche distributions, with an avalanche dimension D = 1.89(3), gives strong indications towards self-organized criticality in this system. Furthermore we determine exponents governing the roughening dynamics of the flux surface using some universal scaling relations. These exponents are compared to those obtained from a standard roughening analysis., Comment: 4 pages, 4 figures, submitted to PRL

Published
2004

16. Avalanches and Self-Organized Criticality in superconductors.

Author

Wijngaardena, R. J., Welling, M. S., Aegerter, C. M., and Menghini, M.

Subjects
*SUPERCONDUCTORS, *AVALANCHES, *NATURAL disasters, *MAGNETOOPTICS, *MAGNETOOPTICAL devices, *DENSITY
Abstract

We review the use of superconductors as a playground for the experimental study of front roughening and avalanches. Using the magneto-optical technique, the spatial distribution of the vortex density in the sample is monitored as a function of time. The roughness and growth exponents corresponding to the vortex `landscape' are determined and compared to the exponents that characterize the avalanches in the framework of Self-Organized Criticality. For those situations where a thermo-magnetic instability arises, an analytical non-linear and non-local model is discussed, which is found to be consistent to great detail with the experimental results. On anisotropic substrates, the anisotropy regularizes the avalanches. [ABSTRACT FROM AUTHOR]

Published
2006
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17. Noise correction for roughening analysis of magnetic flux profiles in YBa2Cu3O7—x.

Author

Welling, M. S., Aegerter, C. M., and Wijngaarden, R. J.

Subjects
*MAGNETIC flux, *THIN films, *NOISE, *SURFACE roughness, *STATISTICAL correlation
Abstract

Analyzes the roughening of magnetic flux profiles in the critical state of YBa2Cu3O7-x thin films. Methods used to characterize the self-affine behavior; Impact of noise on the correlation functions; Experimental details.

Published
2004
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18. Noise correction for roughening analysis of magnetic flux profiles in YBa2Cu3O7—x.

Author

Welling, M. S., Aegerter, C. M., and Wijngaarden, R. J.

Subjects
MAGNETIC flux, THIN films, NOISE, SURFACE roughness, STATISTICAL correlation
Abstract

Analyzes the roughening of magnetic flux profiles in the critical state of YBa2Cu3O7-x thin films. Methods used to characterize the self-affine behavior; Impact of noise on the correlation functions; Experimental details.

Published
2004
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19. Determination of the stochastic evolution equation from noisy experimental data.

Author

Maunuksela, J., Myllys, M., Merikoski, J., Timonen, J., Kärkkäinen, T., Welling, M. S., and Wijngaarden, R. J.

Subjects
STOCHASTIC analysis, FLUCTUATIONS (Physics), WIENER processes, EVOLUTION equations, NOISE, MAGNETIC flux
Abstract

: We have determined the coefficients of the Kardar-Parisi-Zhang equation as functions of coarse graining, which best describe the time evolution and spatial behavior observed for slow-combustion fronts in sheets of paper and magnetic flux fronts in a thin-film high-Tc superconductor. Reconstruction of the relevant equation of motion and its coefficients was mainly based on the inverse method proposed by Lam and Sander [Phys. Rev. Lett. 71, 561 (1993)]. The coefficient of the nonlinear term was also determined from the local slope-dependence of the front velocity. [ABSTRACT FROM AUTHOR]

Published
2003
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21. The price of prints.

Author

Welling, M. S.

Abstract

A letter to the editor is presented about pricing of prints.

Published
2001

22. [Pharmacotherapy for obesity].

Author

van Rossum EFC, Welling MS, van der Voorn B, van der Valk ES, Abawi O, and van den Akker ELT

Subjects
Bariatric Surgery, Bupropion therapeutic use, Combined Modality Therapy, Drug Combinations, Drug Therapy, Combination, Humans, Hunger drug effects, Life Style, Liraglutide therapeutic use, Naltrexone therapeutic use, Satiation drug effects, Treatment Outcome, Weight Loss drug effects, Anti-Obesity Agents therapeutic use, Obesity therapy
Abstract

Obesity is a complex endocrine disease, mainly caused by environmental, behavioral and biological factors. Maintaining weight loss is extremely difficult due to the neuro-endocrine dysregulations that stimulate the body to return to the previous, increased, weight. Identifying underlying weight-gaining factors is needed, including medication-related, psychological and endocrine factors, as well as monogenic obesity. The cornerstone of treatment is optimization of lifestyle and all other contributing factors. Achieving at least 5% weight loss already has important health benefits. If combined lifestyle intervention (CLI) alone is not successful, pharmacotherapy or bariatric surgery can be added for patients with increased weight-related health risks. Recently, novel pharmacotherapy became available, among which, liraglutide 3 mg and the combination therapy naltrexone/bupropion, which leads to an additional 5-6% mean weight loss compared to CLI alone. For rare forms of obesity there are specific drugs that target defects in the regulation of hunger and satiety. Promising new pharmacotherapy for obesity is under development.

Published
2021

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