Search results for "FREQUENCY"
showing 10 items of 2158 documents
Characteristics and treatment of Multiple Sclerosis-related trigeminal neuralgia: An Italian multi-centre study
2019
Abstract Background The prevalence of trigeminal neuralgia (TN) in Multiple Sclerosis (MS) patients is higher than in the general population and its management can be particularly challenging. Our aim is to describe the characteristics, treatment and prognostic factors of MS-related TN in a retrospective multicentre study. Methods Neurologists members of the RIREMS group (Rising Researchers in MS) enrolled MS patients with a TN diagnosis and filled out a spreadsheet comprising their clinical data. Results Population consisted of 298 patients. First-choice preventive treatments were carbamazepine and oxcarbazepine. A surgical procedure was performed in 81 (30%) patients, most commonly gamma …
Sequential effects in the lexical decision task: the role of the item frequency of the previous trial.
2003
Two lexical decision experiments were conducted to determine whether there is a specific, localized influence of the item frequency of consecutive trials (i.e., first-order sequential effects) when the trials are not related to each other. Both low-frequency words and nonwords were influenced by the frequency of the precursor word (Experiment 1). In contrast, high-frequency words showed little sensitivity to the frequency of the precursor word (Experiment 2), although they showed longer reaction times for word trials preceded by a nonword trial. The presence of sequential effects in the lexical decision task suggests that participants shift their response criteria on a trial-by-trial basis.
The effect of neighborhood frequency in reading: Evidence with transposed-letter neighbors
2007
Transposed-letter effects (e.g., jugde activates judge) pose serious models for models of visual-word recognition that use position-specific coding schemes. However, even though the evidence of transposed-letter effects with nonword stimuli is strong, the evidence for word stimuli is scarce and inconclusive. The present experiment examined the effect of neighborhood frequency during normal silent reading using transposed-letter neighbors (e.g., silver, sliver). Two sets of low-frequency words were created (equated in the number of substitution neighbors, word frequency, and number of letters), which were embedded in sentences. In one set, the target word had a higher frequency transposed-le…
The frequency effect for pseudowords in the lexical decision task
2005
Four experiments were designed to investigate whether the frequency of words used to create pseudowords plays an important role in lexical decision. Computational models of the lexical decision task (e.g., the dual route cascaded model and the multiple read-out model) predict that latencies to low-frequency pseudowords should be faster than latencies to high-frequency pseudowords. Consistent with this prediction, results showed that when the pseudowords were created by replacing one internal letter of the base word (Experiments 1 and 3), high-frequency pseudowords yielded slower latencies than low-frequency pseudowords. However, this effect occurred only in the leading edge of the response …
Decoding Emotional Valence from Electroencephalographic Rhythmic Activity
2017
We attempt to decode emotional valence from electroencephalographic rhythmic activity in a naturalistic setting. We employ a data-driven method developed in a previous study, Spectral Linear Discriminant Analysis, to discover the relationships between the classification task and independent neuronal sources, optimally utilizing multiple frequency bands. A detailed investigation of the classifier provides insight into the neuronal sources related with emotional valence, and the individual differences of the subjects in processing emotions. Our findings show: (1) sources whose locations are similar across subjects are consistently involved in emotional responses, with the involvement of parie…
Self-Trapping of Magnetic Oscillation Modes in Landau Flux-Closure Structures
2005
We investigated the magnetodynamics in rectangular Permalloy platelets by means of time-resolved x-ray photoemission microscopy. 10 nm thick platelets of size 16 x 32 microm were excited by an oscillatory field along the short side of the sample with a fundamental frequency of 500 MHz and considerable contributions of higher harmonics. Under the influence of the oscillatory field, the Néel wall in the initial classical Landau pattern shifts away from the center, corresponding to an induced magnetic moment perpendicular to the exciting field. This phenomenon is explained by a self-trapping effect of the dominating spin-wave mode when the system is excited just below the resonance frequency. …
Pressure dependence of the low-frequency dielectric constant of KNbO_3
1997
The effect of pressure on the low-frequency dielectric constant, $\epsilon_0$, of single crystals of KNbO_3 is investigated by means of capacitance measurements. The dielectric constant increases with pressure up to 22.5 kbar, where it exhibits a large value ($\epsilon_0$ = 5000), and then decreases. This change in its behaviour is related to a phase transition induced by pressure. On decompression, the samples do not revert back to the ambient pressure phase.
Structure and dynamic dielectric behaviour of ferroelectric [NH2(CH3)2]3Sb2Br9(DMABA)
2000
The crystal structure of DMABA has been determined at 293 and 180 K. It crystallizes in the monoclinic P21/c space group. The structure was refined to R1 = 0.0466 for 1269 independent reflections at 293 K and R1 = 0.038 for 1728 reflections at 180 K. DMABA is isomorphous with the chlorine analogue, DMACA. Its anionic sublattice forms corrugated two-dimensional layers in the bc plane. There are two crystallographically independent, disordered dimethylammonium cations in the crystal structure. One of them occupies cavities inside the polyanionic layers; the other is located between the layers. The temperature dependence of lattice parameters has been determined between 100 and 290 K. The pres…
Uniaxial Pressure Effects on the Dielectric Properties of the PLZT-x/65/35 (x = 9.75 and 10) Ceramics
2012
The influence of uniaxial pressure (0-1000 bars) applied parallel to the ac electric field on the dielectric properties of PLZT-x/65/35 ceramics (x = 9.75 and 10) was investigated. The results show that the applied stress has a significant influence on the dielectric properties of PLZT ceramics. Applying uniaxial pressure leads to the reduction of the electric permittivity (ϵ) peak and the frequency dispersion. Moreover, the peak of ϵ becomes diffuse and shifts to a higher temperature with increasing pressure. The results show that applying uniaxial pressure induces similar effects as the increase in Ti−ion concentration in the PZT system. We interpreted our results based on the domain swit…
Dielectric Characterization of Fruit Nectars at Low RF Frequencies
2015
Dielectric properties of apple, apricot, peach, and pear nectars were studied in the frequency range from 15 kHz to 30 MHz and the temperature range from 25 to 60 degrees C. Both the relative dielectric constants and the dielectric loss factors decreased by increasing frequency and increased linearly with increasing temperature with values in the order 10(4)-10(2) and 10(5)-10(2), respectively. The power dissipation densities and the power penetration depths were found to increase linearly with temperature. Power dissipation densities remained essentially constant for all the samples while power penetration depths decreased significantly on increasing frequency. The dependence of each of th…