Search results for " frequency"
showing 10 items of 1398 documents
Flip angle considerations in (3)helium-MRI.
2000
3Helium-MRI ((3)He-MRI) can be used for analysis of lung function, e. g. dynamic imaging of ventilation and gas diffusion within the lung, assessment of intrapulmonary oxygen concentrations and their time course. During imaging, the irreversible signal loss due to depolarizing radio frequency excitations can be described using the flip angle (FA) alpha. This parameter has to be quantified in order to account for it during quantitative assessment of the (3)helium signal intensity and its temporal development. This technical report reviews two different methods to determine alpha. Limitations and possible error sources of each method are discussed.
Space–bandwidth product of optical signals and systems
1996
The space–bandwidth product (SW) is fundamental for judging the performance of an optical system. Often the SW of a system is defined only as a pure number that counts the degrees of freedom of the system. We claim that a quasi-geometrical representation of the SW in the Wigner domain is more useful. We also represent the input signal as a SW in the Wigner domain. For perfect signal processing it is necessary that the system SW fully embrace the signal SW.
Mutual Information Analysis of Brain-Heart Interactions in Epileptic Children
2021
In this work we apply the network physiology paradigm to retrieve information from central and autonomic nervous systems before focal epileptic seizure, represented respectively by electroencephalogram (EEG) signals and R-R intervals (RRI), and investigate on the presence and strength of brain-heart interactions by computing mutual information (MI) measures. Statistical significance of MI values was tested through surrogate time series generated with the random shuffle approach. Our results suggest that the proposed method for aligning signals representing brain and heart activity measured with different sampling rates, is capable of revealing coupling between RRI representing heart system,…
Missense and nonsense mutations in melanocortin 1 receptor (MC1R) gene of different goat breeds: association with red and black coat colour phenotype…
2009
Abstract Background Agouti and Extension loci control the relative amount of eumelanin and pheomelanin production in melanocytes that, in turn, affects pigmentation of skin and hair. The Extension locus encodes the melanocortin 1 receptor (MC1R) whose permanent activation, caused by functional mutations, results in black coat colour, whereas other inactivating mutations cause red coat colour in different mammals. Results The whole coding region of the MC1R gene was sequenced in goats of six different breeds showing different coat colours (Girgentana, white cream with usually small red spots in the face; Maltese, white with black cheeks and ears; Derivata di Siria, solid red; Murciano-Granad…
Systematic screening for mutations in the human serotonin-2A (5-HT2A) receptor gene: Identification of two naturally occurring receptor variants and …
1996
A statistically significant association between a silent mutation (102T/C) in the serotonin-2A (5-HT2A) receptor gene and schizophrenia has recently been reported in a sample of Japanese patients and healthy controls. This finding suggests that genetic predisposition to schizophrenia may be affected by a functional 5-HT2A receptor variant that is in linkage disequilibrium with 102T/C. In the present study, we have sought to identify genetic variation in the 5-HT2A receptor gene by screening genomic DNA samples from 91 unrelated subjects comprising 45 patients with schizophrenia and 46 healthy controls by using single-strand conformation analysis. We have identified four nucleotide sequence …
Research and Implementation of Energy Dispersal Algorithm for DRM System
2020
The article investigates the randomization algorithm of the OFDM signal energy used in modern digital broadcasting systems. Transmission part of the DRM system was modeled in MATLAB/Simulink software environment, bit sequences allocation tests were conducted using the original information signal and the corresponding modulation symbols with a scrambling algorithm and without it.
A performance study of LTE MIMO-OFDM systems using the extended one-ring MIMO channel model
2012
In this paper, we consider a long-term evolution (LTE) system for the downlink by using multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) techniques. The downlink channel is modeled by the socalled extended MIMO one-ring model. This model extends the well-known narrowband one-ring model with respect to frequency selectivity. The symbol error rate (SER) performance of the LTE MIMO-OFDM system is investigated for the downlink by employing different kinds of spatial encoders, where it is assumed that the channel state information (CSI) is perfectly known. For comparison, the space-time block coding (STBC) scheme, the vertical Bell Laboratories layered spac…
Reading traffic signs while driving: Are linguistic word properties relevant in a complex, dynamic environment?
2019
When driving a vehicle, do we read the words displayed on traffic signs just as we do in more standard conditions? In the driving context, stimulus quality is generally worse, and reading has to be performed at the same time as we are doing other tasks. In the present work, we examined the effects of word frequency and word length on reading in such circumstances. A stimulus presentation mimicking the approach to the traffic sign increased the effect of word frequency, but not the effect of word length, on reading latency. In addition, performing the reading task while driving along a simulated route produced similar results. Therefore, in the context of the driving activity, the advantage …
Periodic Orthogonal Wavelets and Wavelet Packets
2018
In this chapter, we discuss how to derive versatile families of periodic discrete-time orthogonal wavelets and wavelet packets from discrete and discrete-time splines outlined in Chap. 3. These wavelets and wavelet packets, although not having compact supports, are well localized in the time domain. They can have any number of discrete vanishing moments. Their DFT spectra tend to have a rectangular shape when the spline order grows and provide a collection of refined splits of the Nyquist frequency band. The wavelet and wavelet packet transforms are implemented in a fast way using the FFT.
Analysis of multi degree of freedom systems with fractional derivative elements of rational order
2014
In this paper a novel method based on complex eigenanalysis in the state variables domain is proposed to uncouple the set of rational order fractional differential equations governing the dynamics of multi-degree-of-freedom system. The traditional complex eigenanalysis is appropriately modified to be applicable to the coupled fractional differential equations. This is done by expanding the dimension of the problem and solving the system in the state variable domain. Examples of applications are given pertaining to multi-degree-of-freedom systems under both deterministic and stochastic loads.