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Wyszukujesz frazę "Lehmann, Tomasz" wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
Attention-based U-Net for image demoiréing
Autorzy:
Lehmann, Tomasz M.
Powiązania:
https://bibliotekanauki.pl/articles/2201228.pdf
Data publikacji:
2022
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Instytut Informatyki Technicznej
Tematy:
image demoiréing
computer vision
attention U-Net
cross-sampling
Opis:
Image demoiréing is a particular example of a picture restoration problem. Moiré is an interference pattern generated by overlaying similar but slightly offset templates. In this paper, we present a deep learning based algorithm to reduce moiré disruptions. The proposed solution contains an explanation of the cross-sampling procedure - the training dataset management method which was optimized according to limited computing resources. Suggested neural network architecture is based on Attention U-Net structure. It is an exceptionally effective model which was not proposed before in image demoiréing systems. The greatest improvement of this model in comparison to U-Net network is the implementation of attention gates. These additional computing operations make the algorithm more focused on target structures. We also examined three MSE and SSIM based loss functions. The SSIM index is used to predict the perceived quality of digital images and videos. A similar approach was applied in various computer vision areas. The author’s main contributions to the image demoiréing problem contain the use of the novel architecture for this task, innovative two-part loss function, and the untypical use of the cross-sampling training procedure.
Źródło:
Machine Graphics & Vision; 2022, 31, 1/4; 3--17
1230-0535
2720-250X
Pojawia się w:
Machine Graphics & Vision
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inhibition of CYP17 expression by adrenal androgens and transforming growth factor β in adrenocortical cells.
Autorzy:
Biernacka-Łukanty, Justyna
Lehmann, Tomasz
Trzeciak, Wiesław
Powiązania:
https://bibliotekanauki.pl/articles/1041500.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
CYP17
adrenocortical cells
TGF-β
androgens
expression
Opis:
Cytochrome P450c17, encoded by the CYP17 gene, is a component of the 17a-hydroxylase/17,20-lyase enzyme complex essential for production of adrenal glucocorticoids and androgens as well as gonadal androgens. The expression of CYP17 in adrenocortical cells is stimulated by corticotropin (ACTH) via the signal transduction pathway involving cAMP and protein kinase A (PKA). Thus, in addition to glucocorticoids, ACTH stimulates formation of adrenal androgens, which are known to induce transforming growth factor β (TGF-β) secretion. TGF-β in turn inhibits steroid hormone output by attenuating both basal and ACTH-dependent expression of CYP17. The present study revealed that treatment of bovine and human H295R adrenocortical cells with androgens resulted in a decrease in the basal level of CYP17 transcript and cortisol secretion, without affecting forskolin-stimulated levels. We also demonstrated that in H295R cells TGF-β inhibited both basal and forskolin-stimulated accumulation of CYP17 mRNA. Determination of promoter activity, directing luciferase reporter gene expression in H295R cells transfected with deletion fragments of bovine CYP17 promoter, indicated that the -483 to -433 bp fragment of the promoter was necessary for the inhibitory action of TGF-β on CYP17 expression. It is concluded that in bovine and human adrenocortical cells, androgens inhibit basal CYP17 expression probably at the transcriptional level and independently of the effect of TGF-β.
Źródło:
Acta Biochimica Polonica; 2004, 51, 4; 907-917
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temporal pattern of the induction of SF-1 gene expression by the signal transduction pathway involving 3',5'-cyclic adenosine monophosphate.
Autorzy:
Lehmann, Tomasz
Biernacka-Łukanty, Justyna
Saraco, Nora
Langlois, Dominique
Li, Jacques
Trzeciak, Wiesław
Powiązania:
https://bibliotekanauki.pl/articles/1041435.pdf
Data publikacji:
2005
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
steroidogenensis
CYP11A1
Y-1 cells
SF-1
cAMP pathway
Opis:
The objective of our study was to investigate the effect of stimulation of the cAMP-dependent pathway on the expression of an orphan nuclear receptor, SF-1/Ad4BP in mouse adrenal tumour, Y-1 cells in culture. We evaluated the temporal pattern of the effects of corticotropin (ACTH) and the adenylyl cyclase activator forskolin on the level of SF-1 mRNA, and compared the time course of induction of SF-1 with that of CYP11A1. Forskolin, corticotropin and 8-Br-cAMP significantly elevated the level of the SF-1 transcript, after 1.5 h of incubation, with a concomitant increase of SF-1 protein level, observed after 6 h. The CYP11A1 transcript increased gradually over the incubation period, and reached the maximal level after 12 to 24 h. The steady-state level of the SF-1 transcript was unaffected by forskolin when the cells were incubated with actinomycin D, indicating that stimulation of the cAMP pathway results in enhanced transcription of the gene. The effect of forskolin was augmented by cycloheximide, suggesting that an inhibitory protein, whose synthesis was inhibited by cycloheximide, could be involved in negative regulation of SF-1 expression. It is concluded that SF-1 expression is positively regulated by the cAMP pathway at the transcriptional level, and can represent the primary event in cAMP-mediated induction of steroid hormone synthesis in Y-1 cells.
Źródło:
Acta Biochimica Polonica; 2005, 52, 2; 485-491
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Xception-based Architecture with Cross-sampled Training for Image Quality Assessment on KonIQ-10ĸ
Autorzy:
Tomasz, M. Lehmann
Przemyslaw, Rokita
Powiązania:
https://bibliotekanauki.pl/articles/31339412.pdf
Data publikacji:
2023
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Instytut Informatyki Technicznej
Tematy:
image quality assessment
computer vision
Xception
Opis:
Image quality assessment is a crucial task in various fields such as digital photography, online content creation, and automated quality control, as it ensures an optimal visual experience and aids in maintaining consistent standards. In this paper, we propose an efficient method for training image quality assessment models on the KonIQ-10ĸ dataset. Our novel approach utilizes a dual-Xception architecture that analyzes both the image content and additional image parameters, outperforming traditional single convolutional models. We introduce cross-sampling methods with random draw sampling of instances from majority classes, effectively enhancing prediction quality in the Mean Opinion Score(MOS) ranges that are underrepresented in the database. This methodology allows us to achieve near state-of-the-art results with limited computing costs and resources. Most importantly, our predictions across the entire spectrum of MOS values maintain consistent quality. Because of using a novel and highly effective method for image sampling, we achieved these results with much lower computational cost, making our approach the most effective way of MOS estimation on the KonIQ-10ĸ database.
Źródło:
Machine Graphics & Vision; 2023, 32, 2; 109-127
1230-0535
2720-250X
Pojawia się w:
Machine Graphics & Vision
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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