Search results for "ACOUSTIC"
showing 10 items of 1590 documents
Invariance of Lyapunov exponents and Lyapunov dimension for regular and irregular linearizations
2014
Nowadays the Lyapunov exponents and Lyapunov dimension have become so widespread and common that they are often used without references to the rigorous definitions or pioneering works. It may lead to a confusion since there are at least two well-known definitions, which are used in computations: the upper bounds of the exponential growth rate of the norms of linearized system solutions (Lyapunov characteristic exponents, LCEs) and the upper bounds of the exponential growth rate of the singular values of the fundamental matrix of linearized system (Lyapunov exponents, LEs). In this work the relation between Lyapunov exponents and Lyapunov characteristic exponents is discussed. The invariance…
The chaotic Dadras–Momeni system: control and hyperchaotification
2015
In this paper a novel three-dimensional autonomous chaotic system, the so called Dadras-Momeni system, is considered and two different control techniques are employed to realize chaos control and chaos synchronization. Firstly, the optimal control of the chaotic system is discussed and an open loop feedback controller is proposed to stabilize the system states to one of the system equilibria, minimizing the cost function by virtue of the Pontryagin’s minimum principle. Then, an adaptive control law and an update rule for uncertain parameters, based on Lyapunov stability theory, are designed both to drive the system trajectories to an equilibrium or to realize a complete synchronization of t…
Impact of local order and stoichiometry on the ultrafast magnetization dynamics of Heusler compounds
2015
Nowadays, a wealth of information on ultrafast magnetization dynamics of thin ferromagnetic films exists in the literature. Information is, however, scarce on bulk single crystals, which may be especially important for the case of multi-sublattice systems. In Heusler compounds, representing prominent examples for such multi-sublattice systems, off-stoichiometry and degree of order can significantly change the magnetic properties of thin films, while bulk single crystals may be generally produced with a much more well-defined stoichiometry and a higher degree of ordering. A careful characterization of the local structure of thin films versus bulk single crystals combined with ultrafast demag…
Low-Cost Solution for Magnetic Field Mapping Device
2018
Distribution of magnetic field around different magnetic objects is important for various applications of magnetic materials. Field distribution can be measured with a 3-axis Hall probe sensor, which is moved around the sample. There are excellent systems available in market for this purpose for example, magnetic field mapper MMS-1A-RS from SENIS AG. However, these systems are quite expensive, starting from 25000=C. Here we demonstrate how a simple automated magnetic field mapper can be made from common parts found in laboratories, test it to verify accuracy, compare results with numerical simulations and discuss the benefits of this low-cost alternative.
Interface magnetization of ultrathin epitaxial Co2FeSi(110)/Al2O3films
2007
Element-specific magnetic properties of ultrathin epitaxial Co2FeSi(110) films were measured using x-ray magnetic circular dichroism (XMCD). The epitaxial Heusler films were grown by RF magnetron sputtering on substrates. The magnetization of thicker films as determined by XMCD is smaller than expected for a half-metallic material. In addition, the magnetization decreases considerably for films thinner than 10 nm. The thickness dependence of the magnetic moment can be described by introducing a certain number of dead layers representing a deficiency of magnetization at the interfaces. Quantitative evaluation results in a dead layer thickness of 0.8 nm at room temperature, consisting of a te…
A new voice from Sardinia: Uromenus annae (Targioni-Tozzetti, 1881 (Insecta: Orthoptera: Tettigoniidae: Bradyporinae: Ephippigerini)
2019
Recent findings of the Sardinian endemic Bushcricket Uromenus annae (Targioni Tozzetti, 1881) allowed the authors to retrace the nomenclatorial history of the species. The rearing of living specimens resulted in the recording of the male song, previously unknown. Since the Neotype previously established by Fontana & Buzzetti (2001) is lost, a new Neotype is here designated. Affinities with other congeneric species are discussed.
The Structure and Usage of Female and Male Mouse Ultrasonic Vocalizations Reveal only Minor Differences
2012
Ultrasonic vocalizations (USV) of mice are increasingly recognized as informative dependent variables in studies using mouse models of human diseases. While pup vocalizations primarily serve to re-establish contact with the mother, adult male ‘‘songs’’ were considered to be courtship signals. Alternatively, mouse USVs may generally function as territorial signals. To distinguish between these two hypotheses, we compared the structure and usage of adult male and female USVs in staged resident-intruder encounters. If calls function primarily as courtship signals, males should respond stronger than females, specifically when presented with a female intruder. Refuting this hypothesis, we found …
Hearing in Real-Life Environments (HERE) : Structure and Reliability of a Questionnaire on Perceived Hearing for Older Adults
2019
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Beneficial effects of choir singing on cognition and well-being of older adults: Evidence from a cross-sectional study.
2021
Background and objectivesChoir singing has been associated with better mood and quality of life (QOL) in healthy older adults, but little is known about its potential cognitive benefits in aging. In this study, our aim was to compare the subjective (self-reported) and objective (test-based) cognitive functioning of senior choir singers and matched control subjects, coupled with assessment of mood, QOL, and social functioning.Research design and methodsWe performed a cross-sectional questionnaire study in 162 healthy older (age ≥ 60 years) adults (106 choir singers, 56 controls), including measures of cognition, mood, social engagement, QOL, and role of music in daily life. The choir singers…
Multisensory integration in hemianopia and unilateral spatial neglect: Evidence from the sound induced flash illusion.
2016
Recent neuropsychological evidence suggests that acquired brain lesions can, in some instances, abolish the ability to integrate inputs from different sensory modalities, disrupting multisensory perception. We explored the ability to perceive multisensory events, in particular the integrity of audio-visual processing in the temporal domain, in brain-damaged patients with visual field defects (VFD), or with unilateral spatial neglect (USN), by assessing their sensitivity to the 'Sound-Induced Flash Illusion' (SIFI). The study yielded two key findings. Firstly, the 'fission' illusion (namely, seeing multiple flashes when a single flash is paired with multiple sounds) is reduced in both left- …