MENTOR: Human Perception-Guided Pretraining for Iris Presentation Detection

Incorporating human salience into the training of CNNs has boosted performance in difficult tasks such as biometric presentation attack detection. However, collecting human annotations is a laborious task, not to mention the questions of how and where (in the model architecture) to efficiently incorporate this information into model's training once annotations are obtained. In this paper, we introduce MENTOR (huMan pErceptioN-guided preTraining fOr iris pResentation attack detection), which addresses both of these issues through two unique rounds of training. First, we train an autoencoder to learn human saliency maps given an input iris image (both real and fake examples). Once this representation is learned, we utilize the trained autoencoder in two different ways: (a) as a pre-trained backbone for an iris presentation attack detector, and (b) as a human-inspired annotator of salient features on unknown data. We show that MENTOR's benefits are threefold: (a) significant boost in iris PAD performance when using the human perception-trained encoder's weights compared to general-purpose weights (e.g. ImageNet-sourced, or random), (b) capability of generating infinite number of human-like saliency maps for unseen iris PAD samples to be used in any human saliency-guided training paradigm, and (c) increase in efficiency of iris PAD model training. Sources codes and weights are offered along with the paper.Comment: 8 pages, 3 figure

Znaczenie kliniczne badań nad aromatazą

Aromatase is a member of the cytochrome P450 superfamily that catalyzes the conversion of androgens (C19), namely testosterone and androstenedione, into oestrogens (C18), oestradiol, and oestrone, respectively. The enzyme is active in various tissues in both females and males, thus oestrogens are produced not only in gonads but also in extra-gonadal localizations such as brain, adipose tissue, breast, skin, and bone. Aromatase gene CYP19A1 located on chromosome 15 comprises nine coding exons and a number of alternative non-coding first exons that regulate tissue-specific expression. Studies on local regulation of aromatase expression and activity are important for understanding processes such as growth of oestrogen-dependent breast cancer. Rare clinical conditions of aromatase deficiency and excess have revealed some new and unexpected oestrogen functions in metabolism and bone health in both women and men. They were further studied using transgenic animal models such as aromatase knockout mice (ArKO) or (AROM+) mice overexpressing human aromatase. Research on aromatase was important for its practical outcome as it contributed to the development of aromatase inhibitors (AIs), an effective and safe group of drugs for the first-line endocrine therapy of breast cancer. Further studies are needed to establish AIs application in other oestrogen-dependent conditions, to overcome the resistance in breast cancer patients, and to develop tissue-specific selective inhibitors. (Pol J Endocrinol 2010; 61 (1): 126–134)Aromataza jest enzymem należącym do rodziny cytochromu P450. Katalizuje reakcję hydroksylacji prowadzącą do powstania estrogenów: estradiolu i estronu z androgenowych substratów, odpowiednio: testosteronu i androstendionu. Aktywność enzymu i produkcję estrogenów wykazano w różnych tkankach zarówno u kobiet, jak i u mężczyzn. Poza gonadami aromataza jest aktywna na przykład w mózgu, tkance tłuszczowej, gruczole piersiowym, skórze i kościach. Gen aromatazy CYP19A1, zlokalizowany na chromosomie 15, składa się z dziewięciu kodujących egzonów i alternatywnych niekodujących pierwszych egzonów, których swoista tkankowo transkrypcja reguluje ekspresję genu. Poznanie mechanizmów regulujących lokalną ekspresję i aktywność aromatazy przyczynia się między innymi do lepszego zrozumienia procesów istotnych dla rozwoju estrogenozależnego raka piersi. Opisy klinicznych przypadków niedoboru i nadmiaru aromatazy oraz analiza fenotypu myszy transgenicznych pozbawionych aromatazy (ArKO) lub z jej nadekspresją (AROM+) ujawniły dotychczas nieznane i często zaskakujące funkcje estrogenów u obu płci. Badania podstawowe nad aromatazą znalazły swoje praktyczne zastosowanie w pracach nad inhibitorami aromatazy. Stanowią one obecnie pierwszoplanowe leczenie hormonalne raka piersi kobiet po menopauzie, w przypadku obecności receptorów estrogenowych w komórkach guza. Potrzebne są dalsze badania nad zastosowaniem inhibitorów aromatazy w innych schorzeniach zależnych od estrogenów, nad przeciwdziałaniem rozwojowi oporności powstającej w trakcie terapii oraz opracowaniem selektywnych inhibitorów swoistych tkankowo. (Endokrynol Pol 2010; 61 (1): 126-134

Teaching AI to Teach: Leveraging Limited Human Salience Data Into Unlimited Saliency-Based Training

Machine learning models have shown increased accuracy in classification tasks when the training process incorporates human perceptual information. However, a challenge in training human-guided models is the cost associated with collecting image annotations for human salience. Collecting annotation data for all images in a large training set can be prohibitively expensive. In this work, we utilize ''teacher'' models (trained on a small amount of human-annotated data) to annotate additional data by means of teacher models' saliency maps. Then, ''student'' models are trained using the larger amount of annotated training data. This approach makes it possible to supplement a limited number of human-supplied annotations with an arbitrarily large number of model-generated image annotations. We compare the accuracy achieved by our teacher-student training paradigm with (1) training using all available human salience annotations, and (2) using all available training data without human salience annotations. We use synthetic face detection and fake iris detection as example challenging problems, and report results across four model architectures (DenseNet, ResNet, Xception, and Inception), and two saliency estimation methods (CAM and RISE). Results show that our teacher-student training paradigm results in models that significantly exceed the performance of both baselines, demonstrating that our approach can usefully leverage a small amount of human annotations to generate salience maps for an arbitrary amount of additional training data.Comment: 12 pages, 8 figure

Initial growth of Ba on Ge(001): An STM and DFT study

An ordered alkaline-earth submonolayer on a clean Si(001) surface provides a template for growth of the atomically sharp, crystalline Si-oxide interface that is ubiquitous in the semiconductor device industry. It has been suggested that submonolayers of Sr or Ba on Ge(001) could play a similar role as on structurally identical Si(001), overcoming known limitations of the Ge(001) substrate such as amorphization of its oxidation layers. In this paper the initial stage of the Ba oxidation process, i.e., adsorption and organization of Ba atoms on the Ge(001) surface as a function of temperature (270−770 K) for coverage 1.0 monolayer (ML) and 0.15−0.4 ML, is studied using scanning tunneling microscopy (STM) and density functional theory (DFT). Three types of features have been identified on the Ba-covered Ge(001) surface. They originate from isolated Ba adatoms, isolated Ba ad-dimers, and the Ba ad-dimers assembled into short-range, randomly distributed chains that run across the Ge dimer rows. We find from both STM measurements and DFT calculations that the latter is the dominant structure on Ge(001) with increasing coverage

Higher order reconstructions of the Ge(001) surface induced by a Ba layer

Structural properties of Ba-induced reconstructions on a Ge(001) surface, based on atomic-resolution ultra high-vacuum scanning tunneling microscopy measurements, are discussed. It is shown that while the Ba - Ge layer, which fully covers the surface, is dominated by a phase with an internal 2 × 3 periodicity, it also includes portions of higher order 2 × 6 and 4 × 3 surface reconstructions, always accompanied by 1D protrusions embedded into the dominating phase. Modelling the observed higher order structures, using the elementary cell of the 2 × 3 phase calculated within the density functional theory, is shown to reproduce the experimental data very well. As such the higher order reconstructions can be treated as local defects of the dominating 2 × 3 phase

STM and DFT study on formation and characterization of Ba-incorporated phases on a Ge(001) surface

We characterize the incorporation of Ba adatoms into the Ge(001) surface, resulting in the formation of one-dimensional structures with an internal 2×3 periodicity, after the deposition of Ba atoms at 970 K or at room temperature followed by a 770 K anneal. Scanning tunneling microscopy (STM) data were compared with theoretically simulated STM images generated by density functional theory electronic structure calculations. Excellent agreement between experiment and simulation was found when using an adopted structural model that assumes partial removal of the surface Ge dimers in the [1–10] surface direction and subsequent addition of a single Ba atom to the substrate second layer. Structural assignments for a number of defects observed within regions of the 2×3 reconstruction were also obtained

Characterization of a [4Fe-4S]-ferredoxin model based on a concave tetradentate thiol ligand system

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Experimental analysis of waste tyres as a sustainable source of energy

© The Authors, published by EDP Sciences, 2019. Nowadays, the stability of energy supply that additionally should be sustainable is one of the most important global issues. Thus, many new potential energy sources are being investigated. Since automobile industry is growing, a huge amount of waste tyres (WT) occur each year. Pyrolysis of scrap tyres can be considered as a sustainable way to recover significant amounts of energy as well as the valuable materials. Potential of waste tyres in the energy sector is studied in this work. Proximate, ultimate and thermogravimetric (TG) analysis of mechanically grounded WT sample was done. Waste tyres feature high heating value combined with carbon content as high as 87.90 % (on dry ash-free basis). Additionally, TG analysis allows to choose optimal operating temperature for pyrolysis process which is between 350 and 500°C. However, the sulphur content is also relatively high - around 2 wt.% - and it is the most important challenge for utilizing this waste in a thermochemical way.The paper was financial supported by Department of Air Conditioning, Heating, Gas Engineering and Air Protection; Wroclaw University of Science and Technology (No. 0401/0055/18)