•Decomposition of multicomponent multivariate signals which partially overlap in the joint time-frequency domain is presented.•The method is based on the eigenvectors of the signal autocorrelation ...matrix.•The multivariate signal components are obtained as linear combinations of the eigenvectors that minimize the concentration measure in the time-frequency domain.•Simulation results validate the proposed method.
A solution of the notoriously difficult problem of characterization and decomposition of multicomponent multivariate signals which partially overlap in the joint time-frequency domain is presented. This is achieved based on the eigenvectors of the signal autocorrelation matrix. The analysis shows that the multivariate signal components can be obtained as linear combinations of the eigenvectors that minimize the concentration measure in the time-frequency domain. A gradient-based iterative algorithm is used in the minimization process and for rigor, a particular emphasis is given to dealing with local minima associated with the gradient descent approach. Simulation results over illustrative case studies validate the proposed algorithm in the decomposition of multicomponent multivariate signals which overlap in the time-frequency domain.
A class of doubly stochastic graph shift operators (GSO) is proposed, which is shown to exhibit: (i) lower and upper L2-boundedness for locally stationary random graph signals, (ii) L2-isometry for ...i.i.d. random graph signals with the asymptotic increase in the incoming neighbourhood size of vertices, and (iii) preservation of the mean of any graph signal – all prerequisites for reliable graph neural networks. These properties are obtained through a statistical consistency analysis of the proposed graph shift operator, and by exploiting the dual role of the doubly stochastic GSO as a Markov (diffusion) matrix and as an unbiased expectation operator. For generality, we consider directed graphs which exhibit asymmetric connectivity matrices. The proposed approach is validated through an example on the estimation of a vector field.
The present study investigated effects of squat resistance training on intermuscular hypertrophy of quadriceps femoris muscles (i.e., rectus femoris, RF; vastus intermedius, VI; vastus medialis, VM; ...and vastus lateralis, VL). Eighteen university students (age: 24.1 ± 1.7 years, 9 females) underwent 7 weeks of parallel squat training (2 days/week) preceded by a 2-week familiarization period. Squat strength (1RM) and cross-sectional area (CSA) of four quadriceps muscles were assessed at baseline and at the end of the study. At posttest, 1RM and CSA of quadriceps muscles significantly increased (p < 0.01), with moderate-to-large effect (ES = 1.25−2.11) for 1RM (8.33 ± 6.64 kg), VM CSA (0.12 ± 0.08 cm2), and VL CSA (0.19 ± 0.09 cm2) and small effect (ES = 0.89−1.13) for RF CSA (0.17 ± 0.15 cm2) and VI CSA (0.16 ± 0.18 cm2). No significant differences were found in the changes of CSA between muscles (F = 0.638, p = 0.593). However, the squat 1RM gain was significantly associated only with the changes in CSA of the VL muscle (r = 0.717, p < 0.001). The parallel squat resulted in significant growth of all quadriceps muscles. However, the novelty of this study is that the increase in strength is associated only with hypertrophy of the VL muscle.
Graph signal processing deals with signals which are observed on an irregular graph domain. While many approaches have been developed in classical graph theory to cluster vertices and segment large ...graphs in a signal independent way, signal localization based approaches to the analysis of data on graph represent a new research direction which is also a key to big data analytics on graphs. To this end, after an overview of the basic definitions of graphs and graph signals, we present and discuss a localized form of the graph Fourier transform. To establish analogy with classical signal processing, spectral domain and vertex domain definitions of the localization window are given next. The spectral and vertex localization kernels are then related to the wavelet transform, followed by their polynomial approximations and a study of filtering and inversion operations. For rigor, the analysis of energy representation and frames in the localized graph Fourier transform is extended to the energy forms of vertex-frequency distributions, which operate even without the requirement to apply localization windows. Another link with classical signal processing is established through the concept of local smoothness, which is subsequently related to the paradigm of signal smoothness on graphs, a lynchpin which connects the properties of the signals on graphs and graph topology. This all represents a comprehensive account of the relation of general vertex-frequency analysis with classical time-frequency analysis, an important but missing link for more advanced applications of graph signal processing. The theory is supported by illustrative and practically relevant examples.
Introduction
Nickel (Ni) is one of the well-known toxic metals found in the environment. However, its influence on thyroid function is not explored enough. Hence, the aim of this study was to analyse ...the potential of Ni to disrupt thyroid function by exploring the relationship between blood Ni concentration and serum hormone levels (TSH, T4, T3, fT4 and fT3), as well as the parameters of thyroid homeostasis (SPINA-GT and SPINA-GD) by using correlation analysis and Benchmark (BMD) concept.
Methods
Ni concentration was measured by ICP-MS method, while CLIA was used for serum hormone determination. SPINA Thyr software was used to calculate SPINA-GT and SPINA-GD parameters. BMD analysis was performed by PROAST software (70.1). The limitations of this study are the small sample size and the uneven distribution of healthy and unhealthy subjects, limited confounding factors, as well as the age of the subjects that could have influenced the obtained results.
Results and discussion
The highest median value for blood Ni concentration was observed for the male population and amounted 8,278 µg/L. Accordingly, the statistically significant correlation was observed only in the male population, for Ni-fT4 and Ni-SPINA-GT pairs. The existence of a dose-response relationship was established between Ni and all the measured parameters of thyroid functions in entire population and in both sexes. However, the narrowest BMD intervals were obtained only in men, for Ni - SPINA-GT pair (1.36-60.9 µg/L) and Ni - fT3 pair (0.397-66.8 µg/L), indicating that even 78.68 and 83.25% of men in our study might be in 10% higher risk of Ni-induced SPINA-GT and fT3 alterations, respectively. Due to the relationship established between Ni and the SPINA-GT parameter, it can be concluded that Ni has an influence on the secretory function of the thyroid gland in men. Although the further research is required, these findings suggest possible role of Ni in thyroid function disturbances.
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Matched Filtering on Directed Graphs Stankovic, Isidora; Brajovic, Milos; Ioana, Cornel ...
IEEE transactions on systems, man, and cybernetics. Systems,
06/2024
Journal Article
Recenzirano
The matched filter is a crucial concept in both signal analysis and convolutional neural networks (CNNs). Previous work has addressed graph matched filtering principles for undirected graphs. This ...article expands upon the existing literature, by exploring matched filtering principles for signals on directed graphs. In such cases, the adjacency matrix is asymmetric, and commonly results in nonorthogonal eigenvectors. The presented concept is supported by a detailed analysis and numerical examples.
Type 2 diabetes mellitus (T2DM) increases the risk of cardiovascular disease, especially myocardial injury. Due to their hypoglycemic effects, glucagon-like peptide-1 receptor agonists (GLP-1RAs) are ...efficiently used for T2DM management. GLP-1RAs also have anti-inflammatory and antioxidative effects and can improve cardiac function. The aim of this study was to investigate the cardioprotective effects of liraglutide, a GLP-1RA, on isoprenaline-induced myocardial injury in rats. The study included four groups of animals. They were pretreated with saline for 10 days + saline on days 9 and 10 (control), saline for 10 days + isoprenaline on days 9 and 10 (isoprenaline group), liraglutide for 10 days + saline on days 9 and 10 (liraglutide group), and liraglutide for 10 days, and on days 9 and 10 isoprenaline was administered. This study evaluated ECG, myocardial injury markers, oxidative stress markers, and pathohistological changes. The results showed that liraglutide mitigated the isoprenaline-induced cardiac dysfunction recorded by ECG. Liraglutide reduced serum markers of myocardial injury such as high-sensitive troponin I, aspartate aminotransferase, alanine aminotransferase, reduced thiobarbituric acid reactive substances, increased catalase and superoxide dismutase activity, increased reduced glutathione level, and improved lipid profile. Liraglutide induced antioxidative protection and alleviated isoprenaline-induced myocardial injury.
An ecologically acceptable "green" method of extraction cold-pressing is applied in order to reduce the use of organic solvents and preserve bioactive substances from raw material. Therefore, the ...work aimed to characterize cold-pressed oils obtained from non-intensively grown walnuts. Walnut samples were collected on the territory of Western and Central Serbia. 12 cold-pressed oils were used for the analysis. The content of water and volatile substances, index of refraction and specific absorbances, content of total phenols and antioxidant activity of the hydrophilic and lipophilic fraction of the oil were examined. Microbiological analyses included: the total number of bacteria, the total number of molds, and the presence of sulphite-reducing clostridia and Escherichia coli. In 11 oil samples, the content of water and volatile substances was in accordance with the national Rulebook. The refractive index varies from 1.4725 to 1.4745 for walnut oils. Cold-pressed walnut oils differ in the ranges of specific absorbances (1.08-1.75 at 232 nm and 0.04-0.15 at 270 nm). The content of total phenols in walnut oil was from 3.25 to 5.41 mg GAE/100 mL. The lipophilic fraction of oils showed a significantly higher antioxidant potential compared to the hydrophilic fraction. The results of DPPH* radical scavenging activities the lipophilic fraction was from 17.53% to 39.21%. In all tested walnut oil samples, the total number of bacteria and molds was low. The presence of sulfite-reducing clostridia and Escherichia coli was not detected. In addition to the general quality and biological value of the oils, it is important that they are microbiologically safe.
An ecologically acceptable "green" method of extraction cold-pressing is applied in order to reduce the use of organic solvents and preserve bioactive substances from raw material. Therefore, the ...work aimed to characterize cold-pressed oils obtained from non-intensively grown walnuts. Walnut samples were collected on the territory of Western and Central Serbia. 12 cold-pressed oils were used for the analysis. The content of water and volatile substances, index of refraction and specific absorbances, content of total phenols and antioxidant activity of the hydrophilic and lipophilic fraction of the oil were examined. Microbiological analyses included: the total number of bacteria, the total number of molds, and the presence of sulphite-reducing clostridia and Escherichia coli. In 11 oil samples, the content of water and volatile substances was in accordance with the national Rulebook. The refractive index varies from 1.4725 to 1.4745 for walnut oils. Cold-pressed walnut oils differ in the ranges of specific absorbances (1.08-1.75 at 232 nm and 0.04-0.15 at 270 nm). The content of total phenols in walnut oil was from 3.25 to 5.41 mg GAE/100 mL. The lipophilic fraction of oils showed a significantly higher antioxidant potential compared to the hydrophilic fraction. The results of DPPH* radical scavenging activities the lipophilic fraction was from 17.53% to 39.21%. In all tested walnut oil samples, the total number of bacteria and molds was low. The presence of sulfite-reducing clostridia and Escherichia coli was not detected. In addition to the general quality and biological value of the oils, it is important that they are microbiologically safe. Keywords: refractive index, specific absorbances, phenolic content, antioxidant capacity, microbiological evaluation Ekoloski prihvatljiva "zelena" metoda ekstrakcije hladno presovanje se primenjuje u cilju smanjenja upotrebe organskih rastvaraca i ocuvanja bioaktivnih materija iz sirovine. Stoga je i cilj rada da se okarakterisu hladno cedena ulja dobijena od neintenzivno gajenih oraha sakupljenih na teritoriji Zapadne i Centralne Srbije. U 12 dobijenih orahovih ulja ispitivan je sadrzaj vode i isparljivih materija, indeks refrakcije i specificne apsorbancije, sadrzaj ukupnih fenola kao i antioksidativna aktivnost hidrofilne i lipofilne frakcije. Mikrobioloske analize su obuhvatile: ukupan broj bakterija, ukupan broj plesni, prisustvo sulfitoredukujucih klostridija i Escherichia coli. U 11 uzoraka ulja sadrzaj vode i isparljivih materija bio je u skladu sa Pravilnikom za nerafinisana ulja. Rezultati su pokazali da se indeks refrakcije ulja kretao od 1,4725 do 1,4745. Takode, medu uzorcima su utvrdene varijacije u specificnim apsorpcijama na 232 i 270 nm (1,08-1,75 na 232 nm i 0,04-0,15 na 270 nm). Sadrzaj ukupnih fenola je iznosio od 3,25 do 5,41 mg GAE/100 mL. Lipofilna frakcija ulja pokazala je znacajno veci antioksidativni potencijal u poredenju sa hidrofilnom frakcijom. Antioksidativna aktivnost lipofilne frakcije ulja, merena DPPH* metodom, iznosila je od 17,53% do 39,21%. Ukupan broj bakterija i plesni bio je nizak. Prisustvo sulfitoredukujucih klostridija kao i Escherichia coli nije detektovano. Pored opsteg kvaliteta i bioloske vrednosti ulja, vazno je da su ulja mikrobioloski bezbedna. Kljucne reci: indeks refrakcije, specificne apsorbance, ukupni fenoli, antioksidativni kapacitet, mikrobioloska evaluacija
