40 research outputs found
Allergenomics of the tick Ixodes ricinus reveal important α-Gal-carrying IgE-binding proteins in red meat allergy
No full textSupplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3864]This is the peer-reviewed version of the following article: Apostolovic, D.; Mihailovic, J.; Commins, S. P.; Wijnveld, M.; Kazimirova, M.; Starkhammar, M.; Stockinger, H.; Platts-Mills, T. A. E.; Cirkovic Velickovic, T.; Hamsten, C.; et al. Allergenomics of the Tick Ixodes Ricinus Reveals Important α-Gal–Carrying IgE-Binding Proteins in Red Meat Allergy. Allergy: European Journal of Allergy and Clinical Immunology 2020, 75 (1), 217–220. [https://doi.org/10.1111/all.13978
Evaluation of seven time-frequency representation algorithms applied to broadband echolocation signals
No full textTime-frequency representation algorithms such as spectrograms have proven to be useful tools in marine biosonar signal analysis. Although there are several different time-frequency representation algorithms designed for different types of signals with various characteristics, it is unclear which algorithms that are best suited for transient signals, like the echolocation signals of echolocating whales. This paper describes a comparison of seven different time-frequency representation algorithms with respect to their usefulness when it comes to marine biosonar signals. It also provides the answer to how close in time and frequency two transients can be while remaining distinguishable as two separate signals in time-frequency representations. This is, for instance, relevant in studies where echolocation signal component azimuths are compared in the search for the exact location of their acoustic sources. The smallest time difference was found to be 20 µs and the smallest frequency difference 49 kHz of signals with a −3 dB bandwidth of 40 kHz. Among the tested methods, the Reassigned Smoothed Pseudo Wigner-Ville distribution technique was found to be the most capable of localizing closely spaced signal components
Automatic time-frequency analysis of echolocation signals using the matched Gaussian multitaper spectrogram
No full textHigh-resolution time-frequency (TF) images of multi-component signals are of great interest for visualization, feature extraction and estimation. The matched Gaussian multitaper spectrogram has been proposed to optimally resolve multi-component transient functions of Gaussian shape. Hermite functions are used as multitapers and the weights of the different spectrogram functions are optimized. For a fixed number of multitapers, the optimization gives the approximate Wigner distribution of the Gaussian shaped function. Increasing the number of multitapers gives a better approximation, i.e. a better resolution, but the cross-terms also become more prominent for close TF components. In this submission, we evaluate a number of different concentration measures to automatically estimate the number of multitapers resulting in the optimal spectrogram for TF images of dolphin echolocation signals. The measures are evaluated for different multi-component signals and noise levels and a suggestion of an automatic procedure for optimal TF analysis is given. The results are compared to other well known TF estimation algorithms and examples of real data measurements of echolocation signals from a beluga whale (Delphinapterus leucas) are presented
The scaled reassigned spectrogram adapted for detection and localisation of transient signals
No full textThe reassigned spectrogram can be used to improve the readability of a time-frequency representation of a non-stationary and multi-component signal. However for transient signals the reassignment needs to be adapted in order to achieve good localisation of the signal components. One approach is to scale the reassignment. This paper shows that by adapting the shape of the time window used with the spectrogram and by scaling the reassignment, perfect localisation can be achieved for a transient signal component. It is also shown that without matching the shape of the window, perfect localisation is not achieved. This is used to both identify the time-frequency centres of components in a multi-component signal, and to detect the shapes of the signal components. The scaled reassigned spectrogram with the matching shape window is shown to be able to resolve close components and works well for multi-components signals with noise. An echolocation signal from a beluga whale (Delphinapterus leucas) provides an example of how the method performs on a measured signal
Scaled reassigned spectrograms applied to linear transducer signals
No full textThis study evaluates the applicability of scaled reassigned spectrograms (ReSTS) on ultrasound radio frequency data obtained with a clinical linear array ultrasound transducer. The ReSTS's ability to resolve axially closely spaced objects in a phantom is compared to the classical cross-correlation method with respect to the ability to resolve closely spaced objects as individual reflectors using ultrasound pulses with different lengths. The results show that the axial resolution achieved with the ReSTS was superior to the cross-correlation method when the reflected pulses from two objects overlap. A novel B-mode imaging method, facilitating higher image resolution for distinct reflectors, is proposed
The Matched Reassignment Applied to Echolocation Data
No full textPrevious studies have shown that measurements of beluga whale (Delphinapterus leucas) and bottlenose dolphin (Tur-siops truncatus) echolocation signals at off-axis angles may be well modeled using a Gaussian bell function or a chirped Gaussian function as envelope. In this paper, we apply a novel technique, the matched window reassignment, for investigation of a range of models of dolphin echolocation transients. Using a set of parameterized skewed envelopes and a dictionary-based estimation algorithm, it is shown that the Rényi entropy can be used as an evaluation measure of the model fit. Acoustic recordings from an array of hydrophones of a beluga's echolocation signal are investigated, where the Gaussian envelope frequency modulation function resulted in the lowest Rényi entropy mean and the two-parametric Gum-bel model showed the best observed fit
Objective detection and time-frequency localization of components within transient signals
No full textAn automatic component detection method for overlapping transient pulses in multi-component signals is presented and evaluated. The recently proposed scaled reassignment technique is shown to have the best achievable resolution for closely located Gaussian shaped transient pulses, even in heavy disruptive noise. As a result, the method automatically detects and counts the number of transients, giving the center times and center frequencies of all components with considerable accuracy. The presented method shows great potential for applications in several acoustic research fields, where coinciding Gaussian shaped transients are analyzed. The performance is tested on measured data from a laboratory pulse-echo setup and from a dolphin echolocation signal measured simultaneously at two different locations in the echolocation beam. Since the method requires little user input, it should be easily employed in a variety of research projects
Evaluation of seven time-frequency representation algorithms applied to broadband echolocation signals [Elektronisk resurs]
No full textTime-frequency representation algorithms such as spectrograms have proven to be useful tools in marine biosonar signal analysis. Although there are several different time-frequency representation algorithms designed for different types of signals with various characteristics, it is unclear which algorithms that are best suited for transient signals, like the echolocation signals of echolocating whales. This paper describes a comparison of seven different time-frequency representation algorithms with respect to their usefulness when it comes to marine biosonar signals. It also provides the answer to how close in time and frequency two transients can be while remaining distinguishable as two separate signals in time-frequency representations. This is, for instance, relevant in studies where echolocation signal component azimuths are compared in the search for the exact location of their acoustic sources. The smallest time difference was found to be 20 µs and the smallest frequency difference 49 kHz of signals with a −3 dB bandwidth of 40 kHz. Among the tested methods, the Reassigned Smoothed Pseudo Wigner-Ville distribution technique was found to be the most capable of localizing closely spaced signal components
