359 research outputs found
Criticality in Dynamic Arrest: Correspondence between Glasses and Traffic
Dynamic arrest is a general phenomenon across a wide range of dynamic
systems, but the universality of dynamic arrest phenomena remains unclear. We
relate the emergence of traffic jams in a simple traffic flow model to the
dynamic slow down in kinetically constrained models for glasses. In kinetically
constrained models, the formation of glass becomes a true (singular) phase
transition in the limit . Similarly, using the Nagel-Schreckenberg
model to simulate traffic flow, we show that the emergence of jammed traffic
acquires the signature of a sharp transition in the deterministic limit \pp\to
1, corresponding to overcautious driving. We identify a true dynamical
critical point marking the onset of coexistence between free flowing and jammed
traffic, and demonstrate its analogy to the kinetically constrained glass
models. We find diverging correlations analogous to those at a critical point
of thermodynamic phase transitions.Comment: 4 pages, 4 figure
Derivation of Instrument Requirements for Polarimetry using Mg, Fe, and Mn lines between 250 and 290 nm
Judge et al. (2021) recently argued that a region of the solar spectrum in
the near-UV between about 250 and 290 nm is optimal for studying magnetism in
the solar chromosphere due to an abundance of Mg II, Fe II, and Fe I lines that
sample various heights in the solar atmosphere. In this paper we derive
requirements for spectropolarimetric instruments to observe these lines. We
derive a relationship between the desired sensitivity to magnetic field and the
signal-to-noise of the measurement from the weak-field approximation of the
Zeeman effect. We find that many lines will exhibit observable polarization
signals for both longitudinal and transverse magnetic field with reasonable
amplitudes
In-vitro volumeberekening met behulp van driedimensionale echoscopie
Driedimensionale echoscopie neemt toe in populariteit.De klinische relevantie van driedimensionale echoscopie voor de verloskunde is echter niet bewezen. Wij veronderstellen dat de mogelijkheid van volumemetingen een meerwaarde zal opleveren voor de klinische praktijk. De standaard gebruikte handmatige methode is bewerkelijk en afhankelijk van de ervaring van de onderzoeker. Het is gelukt een semigeautomatiseerde methode voor volumeberekeningen te ontwikkelen. Deze methode is reproduceerbaar en lijkt betrouwbaar. In dit artikel worden de resultaten besproken van een pilotstudy
QRS classification and spatial combination for robust heart rate detection in low-quality fetal ECG recordings
Non-invasive fetal electrocardiography (ECG) can be used for prolonged monitoring of the fetal heart rate (FHR). However, the signal-to-noise-ratio (SNR) of non-invasive ECG recordings is often insufficient for reliable detection of the FHR. To overcome this problem, source separation techniques can be used to enhance the fetal ECG. This study uses a physiology-based source separation (PBSS) technique that has already been demonstrated to outperform widely used blind source separation techniques. Despite the relatively good performance of PBSS in enhancing the fetal ECG, PBSS is still susceptible to artifacts. In this study an augmented PBSS technique is developed to reduce the influence of artifacts. The performance of the developed method is compared to PBSS on multi-channel non-invasive fetal ECG recordings. Based on this comparison, the developed method is shown to outperform PBSS for the enhancement of the fetal ECG
Exchange bias and interface electronic structure in Ni/Co3O4(011)
A detailed study of the exchange bias effect and the interfacial electronic
structure in Ni/Co3O4(011) is reported. Large exchange anisotropies are
observed at low temperatures, and the exchange bias effect persists to
temperatures well above the Neel temperature of bulk Co3O4, of about 40 K: to
~80 K for Ni films deposited on well ordered oxide surfaces, and ~150 K for Ni
films deposited on rougher Co3O4 surfaces. Photoelectron spectroscopy
measurements as a function of Ni thickness show that Co reduction and Ni
oxidation occur over an extended interfacial region. We conclude that the
exchange bias observed in Ni/Co3O4, and in similar ferromagnetic metallic/Co3O4
systems, is not intrinsic to Co3O4 but rather due to the formation of CoO at
the interface.Comment: 8 pages, 6 figures. Accepted for publication in Physical Review B
Critical bending point in the Lyapunov localization spectra of many-particle systems
The localization spectra of Lyapunov vectors in many-particle systems at low
density exhibit a characteristic bending behavior. It is shown that this
behavior is due to a restriction on the maximum number of the most localized
Lyapunov vectors determined by the system configuration and mutual
orthogonality. For a quasi-one-dimensional system this leads to a predicted
bending point at n_c \approx 0.432 N for an N particle system. Numerical
evidence is presented that confirms this predicted bending point as a function
of the number of particles N.Comment: 4 pages, 4 figure
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