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Seo, Younghun, and Nam Yul Yu. "Additive Orthant Loss for Deep Face Recognition." Applied Sciences 12, no. 17 (August 28, 2022): 8606. http://dx.doi.org/10.3390/app12178606.
Повний текст джерелаАнотація:
In this paper, we propose a novel loss function for deep face recognition, called the additive orthant loss (Orthant loss), which can be combined for softmax-based loss functions to improve the feature-discriminative capability. The Orthant loss makes features away from the origin using the rescaled softplus function and an additive margin. Additionally, the Orthant loss compresses feature spaces by mapping features to an orthant of each class using element-wise operation and 1-bit quantization. As a consequence, the Orthant loss improves the inter-class separabilty and the intra-class compactness. We empirically show that the ArcFace combined with the Orthant loss further compresses and moves the feature spaces farther away from the origin compared to the original ArcFace. Experimental results show that the new combined loss has the most improved accuracy on CFP-FP, AgeDB-30, and MegaFace testing datasets, among some of the latest loss functions.
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V'yugin, V. V., and V. P. Maslov. "Extremal Relations between Additive Loss Functions and the Kolmogorov Complexity." Problems of Information Transmission 39, no. 4 (October 2003): 380–94. http://dx.doi.org/10.1023/b:prit.0000011276.88154.91.
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Zhou, Shengwei, Caikou Chen, Guojiang Han, and Xielian Hou. "Double Additive Margin Softmax Loss for Face Recognition." Applied Sciences 10, no. 1 (December 19, 2019): 60. http://dx.doi.org/10.3390/app10010060.
Повний текст джерелаАнотація:
Learning large-margin face features whose intra-class variance is small and inter-class diversity is one of important challenges in feature learning applying Deep Convolutional Neural Networks (DCNNs) for face recognition. Recently, an appealing line of research is to incorporate an angular margin in the original softmax loss functions for obtaining discriminative deep features during the training of DCNNs. In this paper we propose a novel loss function, termed as double additive margin Softmax loss (DAM-Softmax). The presented loss has a clearer geometrical explanation and can obtain highly discriminative features for face recognition. Extensive experimental evaluation of several recent state-of-the-art softmax loss functions are conducted on the relevant face recognition benchmarks, CASIA-Webface, LFW, CALFW, CPLFW, and CFP-FP. We show that the proposed loss function consistently outperforms the state-of-the-art.
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Khalfallah, Mohammed El-arbi, Mohammed Lakhdar Hadji, and Josep Vives. "Pricing cumulative loss derivatives under additive models via Malliavin calculus." Boletim da Sociedade Paranaense de Matemática 41 (December 23, 2022): 1–15. http://dx.doi.org/10.5269/bspm.51549.
Повний текст джерелаАнотація:
We show that integration by parts formulas based on Malliavin-Skorohod calculus techniques for additive processes help us to compute quantities like ${\E}(L_T h(L_T))$ for different suitable functions $h$ and different models for the cumulative loss process $L_T$. These quantities are important in Insurance and Finance. For example they appear in computing expected shortfall risk measures or stop-loss contracts. The formulas given in the present paper, obtained by simple proofs, generalize the formulas given in a recent paper by Hillairet, Jiao and Réveillac using Malliavin calculus techniques for the standard Poisson process, a particular case of additive process.
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Hüllermeier, Eyke, Marcel Wever, Eneldo Loza Mencia, Johannes Fürnkranz, and Michael Rapp. "A flexible class of dependence-aware multi-label loss functions." Machine Learning 111, no. 2 (January 13, 2022): 713–37. http://dx.doi.org/10.1007/s10994-021-06107-2.
Повний текст джерелаАнотація:
AbstractThe idea to exploit label dependencies for better prediction is at the core of methods for multi-label classification (MLC), and performance improvements are normally explained in this way. Surprisingly, however, there is no established methodology that allows to analyze the dependence-awareness of MLC algorithms. With that goal in mind, we introduce a class of loss functions that are able to capture the important aspect of label dependence. To this end, we leverage the mathematical framework of non-additive measures and integrals. Roughly speaking, a non-additive measure allows for modeling the importance of correct predictions of label subsets (instead of single labels), and thereby their impact on the overall evaluation, in a flexible way. The well-known Hamming and subset 0/1 losses are rather extreme special cases of this function class, which give full importance to single label sets or the entire label set, respectively. We present concrete instantiations of this class, which appear to be especially appealing from a modeling perspective. The assessment of multi-label classifiers in terms of these losses is illustrated in an empirical study, clearly showing their aptness at capturing label dependencies. Finally, while not being the main goal of this study, we also show some preliminary results on the minimization of this parametrized family of losses.
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Zhao, Feng, Peng Zhang, Ran Zhang, and Mengwei Li. "UnifiedFace: A Uniform Margin Loss Function for Face Recognition." Applied Sciences 13, no. 4 (February 11, 2023): 2350. http://dx.doi.org/10.3390/app13042350.
Повний текст джерелаАнотація:
Face recognition has achieved great success due to the development of deep convolutional neural networks (DCNNs) and loss functions based on margin. However, complex DCNNs bring a large number of parameters as well as computational effort, which pose a significant challenge to resource-constrained embedded devices. Meanwhile, the popular margin-based loss functions all introduce only one type of margin and cannot further introduce a larger margin to achieve tighter classification boundary. In contrast to the common approach, we believe that additive and multiplicative margins should be used jointly to introduce larger margins from the margin perspective. Therefore, we propose a new margin-based loss function called UnifiedFace. First, we introduce an additive margin in the target angle activation function. Second, we add a multiplicative margin in the non-target angle. UnifiedFace introduces both additive and multiplicative margins, allowing for the introduction of large margins to achieve more compact intra-class variance and closer separated inter-class variance. In addition, we specifically design efficient face recognition models called GhostFaceNet for resource-constrained embedded devices. Experimental results demonstrate that UnifiedFace achieves state-of-the-art performance or performance competed with popular methods in training datasets of different sizes. UnifiedFace achieves optimal performance in models of varying complexity. Moreover, competitive results are achieved in the large-scale test set IJBB/C, especially the state-of-the-art performance achieved in TAR (FAR=1e−6). GhostFaceNet can significantly improve operational efficiency without significantly degrading recognition performance, making it ideal for embedded devices with limited resources.
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Fang, Le-Heng, Wei Lin, and Qiang Luo. "Brain-Inspired Constructive Learning Algorithms with Evolutionally Additive Nonlinear Neurons." International Journal of Bifurcation and Chaos 28, no. 05 (May 2018): 1850068. http://dx.doi.org/10.1142/s0218127418500682.
Повний текст джерелаАнотація:
In this article, inspired partially by the physiological evidence of brain’s growth and development, we developed a new type of constructive learning algorithm with evolutionally additive nonlinear neurons. The new algorithms have remarkable ability in effective regression and accurate classification. In particular, the algorithms are able to sustain a certain reduction of the loss function when the dynamics of the trained network are bogged down in the vicinity of the local minima. The algorithm augments the neural network by adding only a few connections as well as neurons whose activation functions are nonlinear, nonmonotonic, and self-adapted to the dynamics of the loss functions. Indeed, we analytically demonstrate the reduction dynamics of the algorithm for different problems, and further modify the algorithms so as to obtain an improved generalization capability for the augmented neural networks. Finally, through comparing with the classical algorithm and architecture for neural network construction, we show that our constructive learning algorithms as well as their modified versions have better performances, such as faster training speed and smaller network size, on several representative benchmark datasets including the MNIST dataset for handwriting digits.
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Braems, Elke, Bart Swinnen, and Ludo Van Den Bosch. "C9orf72 loss-of-function: a trivial, stand-alone or additive mechanism in C9 ALS/FTD?" Acta Neuropathologica 140, no. 5 (September 2, 2020): 625–43. http://dx.doi.org/10.1007/s00401-020-02214-x.
Повний текст джерелаАнотація:
Abstract A repeat expansion in C9orf72 is responsible for the characteristic neurodegeneration in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) in a still unresolved manner. Proposed mechanisms involve gain-of-functions, comprising RNA and protein toxicity, and loss-of-function of the C9orf72 gene. Their exact contribution is still inconclusive and reports regarding loss-of-function are rather inconsistent. Here, we review the function of the C9orf72 protein and its relevance in disease. We explore the potential link between reduced C9orf72 levels and disease phenotypes in postmortem, in vitro, and in vivo models. Moreover, the significance of loss-of-function in other non-coding repeat expansion diseases is used to clarify its contribution in C9orf72 ALS/FTD. In conclusion, with evidence pointing to a multiple-hit model, loss-of-function on itself seems to be insufficient to cause neurodegeneration in C9orf72 ALS/FTD.
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Dumaswala, U. J., L. Zhuo, S. Mahajan, P. N. M. Nair, H. G. Shertzer, P. Dibello, and D. W. Jacobsen. "Glutathione protects chemokine-scavenging and antioxidative defense functions in human RBCs." American Journal of Physiology-Cell Physiology 280, no. 4 (April 1, 2001): C867—C873. http://dx.doi.org/10.1152/ajpcell.2001.280.4.c867.
Повний текст джерелаАнотація:
Oxidant stress, in vivo or in vitro, is known to induce oxidative changes in human red blood cells (RBCs). Our objective was to examine the effect of augmenting RBC glutathione (GSH) synthesis on 1) degenerative protein loss and 2) RBC chemokine- and free radical-scavenging functions in the oxidatively stressed human RBCs by using banked RBCs as a model. Packed RBCs were stored up to 84 days at 1–6°C in Adsol or in the experimental additive solution (Adsol fortified with glutamine, glycine, and N-acetyl-l-cysteine). Supplementing the conventional additive with GSH precursor amino acids improved RBC GSH synthesis and maintenance. The rise in RBC γ-glutamylcysteine ligase activity was directly proportional to the GSH content and inversely proportional to extracellular homocysteine concentration, methemoglobin formation, and losses of the RBC proteins band 3, band 4.1, band 4.2, glyceraldehyde-3-phosphate dehydrogenase, and Duffy antigen ( P < 0.01). Reduced loss of Duffy antigen correlated well with a decrease in chemokine RANTES (regulated upon activation, normal T-cell expressed, and secreted) concentration. We conclude that the concomitant loss of GSH and proteins in oxidatively stressed RBCs can compromise RBC scavenging function. Upregulating GSH synthesis can protect RBC scavenging (free radical and chemokine) function. These results have implications not only in a transfusion setting but also in conditions like diabetes and sickle cell anemia, in which RBCs are subjected to chronic/acute oxidant stresses.
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Tobechukwu, Nwakuya Maureen. "Quantile Generalized Additive Model a Robust Alternative to Generalized Additive Model." International Journal of Mathematical Research 10, no. 1 (December 27, 2021): 12–18. http://dx.doi.org/10.18488/journal.24.2021.101.12.18.
Повний текст джерелаАнотація:
Nonparametric regression is an approach used when the structure of the relationship between the response and the predictor variable is unknown. It tries to estimate the structure of this relationship since there is no predetermined form. The generalized additive model (GAM) and quantile generalized additive (QGAM) model provides an attractive framework for nonparametric regression. The QGAM focuses on the features of the response beyond the central tendency, while the GAM focuses on the mean response. The analysis was done using gam and qgam packages in R, using data set on live-births, fertility-rate and birth-rate, where, live-birth is the response with fertility-rate and birth-rate as the predictors. The spline basis function was used while selecting the smoothing parameter by marginal loss minimization technique. The result shows that the basis dimension used was sufficient. The QGAM results show the effect of the smooth functions on the response variable at 25th, 50th, 75th and 95th quantiles, while the GAM showed only the effect of the predictors on the mean response. The results also reveal that the QGAM have lower Akaike information criterion (AIC) and Generalized cross-validation (GVC) than the GAM, hence producing a better model. It was also observed that the QGAM and the GAM at the 50th quantile had the same R2adj(77%), meaning that both models were able to explain the same percentage of variation in the models, this we attribute to the fact that mean regression and median regression are approximately the same, hence the observation is in agreement with existing literature. The plots reveal that some of the residuals of the GAM were seen to fall outside the confidence band while in QGAM all the residuals fell within the confidence band producing a better smooth.
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Gwizdała, W., A. Dawid, and Z. Gburski. "Molecular Dynamics Simulation Study of the Liquid Crystal Phase in a Small Mesogene Cluster (5CB)22." Solid State Phenomena 140 (October 2008): 89–96. http://dx.doi.org/10.4028/www.scientific.net/ssp.140.89.
Повний текст джерелаАнотація:
The molecular dynamics (MD) technique was used to investigate the nano droplet composed of twenty mesogene molecules 4-cyano-4-n-pentylbiphenyl (5CB). The 5CB molecules were treated as rigid bodies, the intermolecular interaction was taken to be the full site-site pairwise additive Lennard-Jones (LJ) potential plus a Coulomb interaction. The radial distribution functions in the temperature range from 150 to 400 K, were calculated as well as the linear and angular velocity autocorrelation functions. In addition the total dipole moment autocorrelation function and dielectric loss of (5CB)22 mesogene cluster were calculated and the liquid crystal ordering in the nanoscale system was studied up to its vaporization temperature.
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Wang, Xiaobo, Shifeng Zhang, Shuo Wang, Tianyu Fu, Hailin Shi, and Tao Mei. "Mis-Classified Vector Guided Softmax Loss for Face Recognition." Proceedings of the AAAI Conference on Artificial Intelligence 34, no. 07 (April 3, 2020): 12241–48. http://dx.doi.org/10.1609/aaai.v34i07.6906.
Повний текст джерелаАнотація:
Face recognition has witnessed significant progress due to the advances of deep convolutional neural networks (CNNs), the central task of which is how to improve the feature discrimination. To this end, several margin-based (e.g., angular, additive and additive angular margins) softmax loss functions have been proposed to increase the feature margin between different classes. However, despite great achievements have been made, they mainly suffer from three issues: 1) Obviously, they ignore the importance of informative features mining for discriminative learning; 2) They encourage the feature margin only from the ground truth class, without realizing the discriminability from other non-ground truth classes; 3) The feature margin between different classes is set to be same and fixed, which may not adapt the situations very well. To cope with these issues, this paper develops a novel loss function, which adaptively emphasizes the mis-classified feature vectors to guide the discriminative feature learning. Thus we can address all the above issues and achieve more discriminative face features. To the best of our knowledge, this is the first attempt to inherit the advantages of feature margin and feature mining into a unified loss function. Experimental results on several benchmarks have demonstrated the effectiveness of our method over state-of-the-art alternatives. Our code is available at http://www.cbsr.ia.ac.cn/users/xiaobowang/.
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Sasse, Jana, Malte Schön, and Christian Hopmann. "Static Mixers Producible by Additive Manufacturing: Novel Rapid Automatic Optimisation and Practical Evaluation." Polymers 14, no. 21 (November 1, 2022): 4646. http://dx.doi.org/10.3390/polym14214646.
Повний текст джерелаАнотація:
In the extrusion of plastics, the thermal and material homogeneity of the plastic melt at the die entry are of high importance for the extrudate quality. While static mixers are widely used to improve the melt homogeneity, previous attempts at optimisation for reduced pressure loss and improved mixing had to be performed by hand and human experience, limiting the degrees of freedom and efficiency. A new automatic optimisation method based on the open source software OpenFOAM was developed. Using immersed boundary methods, new target functions in the pre-existing routine adjointShapeOptimizationFoam and an additional algorithm checking the suitability for additive manufacturing and fixing the geometry during run-time is presented. The new algorithm is used to optimise an existing static mixer based on an X-type geometry with integrated oil channels, maximising the heat exchange between oil and melt. Based on the results of these simulative optimisations, the best candidates were manufactured using selective laser melting and experimental trials were run. Experimental validation shows that with our optimisation algorithm, a pressure loss reduction of 10% could be achieved. The core melt temperature was reduced by 6 ∘C, improving the thermal homogenisation as well. While the main advantage of this method is the rapid optimisation taking the operating point into account, the trials also showed positive results in off-design operating points. This allows the low-cost design and manufacture of individualised static mixers.
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Borysov, Sergiy I., Brook S. Nepon-Sixt, and Mark G. Alexandrow. "The N Terminus of the Retinoblastoma Protein Inhibits DNA Replication via a Bipartite Mechanism Disrupted in Partially Penetrant Retinoblastomas." Molecular and Cellular Biology 36, no. 5 (December 28, 2015): 832–45. http://dx.doi.org/10.1128/mcb.00636-15.
Повний текст джерелаАнотація:
The N-terminal domain of the retinoblastoma (Rb) tumor suppressor protein (RbN) harbors in-frame exon deletions in partially penetrant hereditary retinoblastomas and is known to impair cell growth and tumorigenesis. However, how such RbN deletions contribute to Rb tumor- and growth-suppressive functions is unknown. Here we establish that RbN directly inhibits DNA replication initiation and elongation using a bipartite mechanism involving N-terminal exons lost in cancer. Specifically, Rb exon 7 is necessary and sufficient to target and inhibit the replicative CMG helicase, resulting in the accumulation of inactive CMGs on chromatin. An independent N-terminal loop domain, which forms a projection, specifically blocks DNA polymerase α (Pol-α) and Ctf4 recruitment without affecting DNA polymerases ε and δ or the CMG helicase. Individual disruption of exon 7 or the projection in RbN or Rb, as occurs in inherited cancers, partially impairs the ability of Rb/RbN to inhibit DNA replication and block G1-to-S cell cycle transit. However, their combined loss abolishes these functions of Rb. Thus, Rb growth-suppressive functions include its ability to block replicative complexes via bipartite, independent, and additive N-terminal domains. The partial loss of replication, CMG, or Pol-α control provides a potential molecular explanation for how N-terminal Rb loss-of-function deletions contribute to the etiology of partially penetrant retinoblastomas.
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McGowan, Erin, Vidita Gawade, and Weihong (Grace) Guo. "A Physics-Informed Convolutional Neural Network with Custom Loss Functions for Porosity Prediction in Laser Metal Deposition." Sensors 22, no. 2 (January 10, 2022): 494. http://dx.doi.org/10.3390/s22020494.
Повний текст джерелаАнотація:
Physics-informed machine learning is emerging through vast methodologies and in various applications. This paper discovers physics-based custom loss functions as an implementable solution to additive manufacturing (AM). Specifically, laser metal deposition (LMD) is an AM process where a laser beam melts deposited powder, and the dissolved particles fuse to produce metal components. Porosity, or small cavities that form in this printed structure, is generally considered one of the most destructive defects in metal AM. Traditionally, computer tomography scans measure porosity. While this is useful for understanding the nature of pore formation and its characteristics, purely physics-driven models lack real-time prediction ability. Meanwhile, a purely deep learning approach to porosity prediction leaves valuable physics knowledge behind. In this paper, a hybrid model that uses both empirical and simulated LMD data is created to show how various physics-informed loss functions impact the accuracy, precision, and recall of a baseline deep learning model for porosity prediction. In particular, some versions of the physics-informed model can improve the precision of the baseline deep learning-only model (albeit at the expense of overall accuracy).
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Genova, Jansller, Antonio Melo, Paulo Rupolo, Silvana Carvalho, Leandro Costa, and Paulo Carvalho. "A summary of feed additives, intestinal health and intestinal alkaline phosphatase in piglet nutrition." Czech Journal of Animal Science 65, No. 8 (August 30, 2020): 281–94. http://dx.doi.org/10.17221/70/2020-cjas.
Повний текст джерелаАнотація:
Weaning is considered the “critical window” in the piglet’s life because it is associated with several stress factors, such as loss of contact with the mother and original litter, solid diet, environmental and structural changes, and the establishment of a new hierarchy. During this abrupt period, several events such as reduced feed intake, high morbidity, susceptibility to enteric infections and post-weaning diarrhoea are observed. The nutritional landscape of the piglet gut is modified, which can compromise the maturity of the gastrointestinal system, the stable intestinal microbiome and the active immunity developed as an indicator of intestinal health. However, with increased awareness of feed safety issues and the development of drug-resistant bacteria, the interest in producing pigs without the use of antimicrobial growth promoters (AGP) is increasing, since long-term use and therapeutic doses of AGP can contribute to the reduction of bacterial diversity and increase of inflammatory bowel disease (IBD). Thus, the most widely researched alternatives include the use of feed additives, feeding strategies, nutraceuticals/functional foods and available handling that can reduce the risk of IBD beyond basic nutritional functions. Studies have reported intestinal alkaline phosphatase as a new nutritional therapy associated with intestinal health which may be a “key additive” in the AGP replacement. In this review article, the purpose is to show some current aspects of feed additive research, addressing a concept of the “intestinal health” from different points of view and properties of alkaline phosphatase.
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Wideman, Jeremy G., Nancy E. Go, Astrid Klein, Erin Redmond, Sebastian W. K. Lackey, Tan Tao, Hubert Kalbacher, Doron Rapaport, Walter Neupert, and Frank E. Nargang. "Roles of the Mdm10, Tom7, Mdm12, and Mmm1 Proteins in the Assembly of Mitochondrial Outer Membrane Proteins in Neurospora crassa." Molecular Biology of the Cell 21, no. 10 (May 15, 2010): 1725–36. http://dx.doi.org/10.1091/mbc.e09-10-0844.
Повний текст джерелаАнотація:
The Mdm10, Mdm12, and Mmm1 proteins have been implicated in several mitochondrial functions including mitochondrial distribution and morphology, assembly of β-barrel proteins such as Tom40 and porin, association of mitochondria and endoplasmic reticulum, and maintaining lipid composition of mitochondrial membranes. Here we show that loss of any of these three proteins in Neurospora crassa results in the formation of large mitochondrial tubules and reduces the assembly of porin and Tom40 into the outer membrane. We have also investigated the relationship of Mdm10 and Tom7 in the biogenesis of β-barrel proteins. Previous work showed that mitochondria lacking Tom7 assemble Tom40 more efficiently, and porin less efficiently, than wild-type mitochondria. Analysis of mdm10 and tom7 single and double mutants, has demonstrated that the effects of the two mutations are additive. Loss of Tom7 partially compensates for the decrease in Tom40 assembly resulting from loss of Mdm10, whereas porin assembly is more severely reduced in the double mutant than in either single mutant. The additive effects observed in the double mutant suggest that different steps in β-barrel assembly are affected in the individual mutants. Many aspects of Tom7 and Mdm10 function in N. crassa are different from those of their homologues in Saccharomyces cerevisiae.
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Sundt, Bjørn. "Discussion on D.C.M. Dickson & H.R. Waters Multi-Period Aggregate Loss Distributions for a Life Portfolio." ASTIN Bulletin 29, no. 2 (November 1999): 311–14. http://dx.doi.org/10.2143/ast.29.2.504617.
Повний текст джерелаАнотація:
In the present discussion we point out the relation of some results in Dickson & Waters (1999) to similar results in Sundt (1998a, b).We shall need some notation. For a positive integer m let m be the set of all m × 1 vectors with positive integer-valued elements and m+ = m ~ {0}. A vector will be denoted by a bold-face letter and each of its elements by the corresponding italic with a subscript denoting the number of the elements; the subscript · denotes the sum of the elements. Let m0 be the class of probability functions on m with a positive probability at 0 and m+ the class of probability functions on m+. For j = 1,…, m we introduce the m × 1 vector ej where the jth element is one and all the other elements zero. We make the convention that summation over an empty range is equal to zero.Let g ∈ m0 be the compound probability function with counting distribution with probability function v ∈ 10 and severity distribution with probability function h ∈ m+; we shall denote this compound probability function by v V h. Sundt (1998a) showed thatwhere φv denotes the De Pril transform of v, given byMotivated by (2) Sundt (1998a) defined the De Pril transform φg of g byThis defines the De Pril transform for all probability functions in m0. Insertion of (2) in (3) givesand by solving φg(X) we obtainSundt (1998a) studies the De Pril transform defined in this way and found in particular that it is additive for convolutions.
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Phillips, Steven, and Jane Elith. "Logistic Methods for Resource Selection Functions and Presence-Only Species Distribution Models." Proceedings of the AAAI Conference on Artificial Intelligence 25, no. 1 (August 4, 2011): 1384–89. http://dx.doi.org/10.1609/aaai.v25i1.7799.
Повний текст джерелаАнотація:
In order to better protect and conserve biodiversity, ecologists use machine learning and statistics to understand how species respond to their environment and to predict how they will respond to future climate change, habitat loss and other threats. A fundamental modeling task is to estimate the probability that a given species is present in (or uses) a site, conditional on environmental variables such as precipitation and temperature. For a limited number of species, survey data consisting of both presence and absence records are available, and can be used to fit a variety of conventional classification and regression models. For most species, however, the available data consist only of occurrence records --- locations where the species has been observed. In two closely-related but separate bodies of ecological literature, diverse special-purpose models have been developed that contrast occurrence data with a random sample of available environmental conditions. The most widespread statistical approaches involve either fitting an exponential model of species' conditional probability of presence, or fitting a naive logistic model in which the random sample of available conditions is treated as absence data; both approaches have well-known drawbacks, and do not necessarily produce valid probabilities. After summarizing existing methods, we overcome their drawbacks by introducing a new scaled binomial loss function for estimating an underlying logistic model of species presence/absence. Like the Expectation-Maximization approach of Ward et al. and the method of Steinberg and Cardell, our approach requires an estimate of population prevalence, $\Pr(y=1)$, since prevalence is not identifiable from occurrence data alone. In contrast to the latter two methods, our loss function is straightforward to integrate into a variety of existing modeling frameworks such as generalized linear and additive models and boosted regression trees. We also demonstrate that approaches by Lele and Keim and by Lancaster and Imbens that surmount the identifiability issue by making parametric data assumptions do not typically produce valid probability estimates.
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Galindo-Trigo, Sergio, Thomas M. Grand, Christian A. Voigt, and Lisa M. Smith. "A malectin domain kinesin functions in pollen and seed development in Arabidopsis." Journal of Experimental Botany 71, no. 6 (January 17, 2020): 1828–41. http://dx.doi.org/10.1093/jxb/eraa023.
Повний текст джерелаАнотація:
Abstract The kinesin family is greatly expanded in plants compared with animals and, with more than a third up-regulated in expression during cell division, it has been suggested that this expansion facilitated complex plant-specific cytoskeletal rearrangements. The cell cycle-regulated kinesins include two with an N-terminal malectin domain, a protein domain that has been shown to bind polysaccharides and peptides when found extracellularly in receptor-like kinases. Although malectin domain kinesins are evolutionarily deep rooted, their function in plants remains unclear. Here we show that loss of MALECTIN DOMAIN KINESIN 2 (MDKIN2) results in stochastic developmental defects in pollen, embryo, and endosperm. High rates of seed abnormalities and abortion occur in mdkin2 mutants through a partial maternal effect. No additive effect or additional developmental defects were noted in mdkin1 mdkin2 double mutants. MDKIN2 is expressed in regions of cell division throughout the plant. Subcellular localization of MDKIN2 indicates a role in cell division, with a possible secondary function in the nuclei. Our results reveal a non-essential but important role for a malectin domain kinesin during development in plants.
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Leifeld, J., C. Bader, E. Borraz, M. Hoffmann, M. Giebels, M. Sommer, and J. Augustin. "Are C-loss rates from drained peatlands constant over time? The additive value of soil profile based and flux budget approach." Biogeosciences Discussions 11, no. 8 (August 15, 2014): 12341–73. http://dx.doi.org/10.5194/bgd-11-12341-2014.
Повний текст джерелаАнотація:
Abstract. Drained peatlands are CO2 hotspots and lose important soil functions over time. In contrast to mineral soils, their high carbon density induces long lasting and high emissions. These emissions can be estimated using various approaches which cover different system boundaries in time and space. Here we compare 5 years flux measurements from manual chambers with a soil profile based method to estimate carbon losses from two temperate fens under different management intensity drained at the end of the 19th century. According to the flux measurements, both grassland sites currently lose significant amounts of carbon as CO2 in the order of 7.1 and 9.1 t CO2-C ha−1a−1 when managed non-intensively or intensively, respectively. Profile based estimates, which make use of the difference in ash concentration along the soil profile, reveal a total of 284 and 619 t C ha−1 since the onset of drainage. These substantial losses are accompanied by a sharp decrease in peat quality as measured by NMR spectroscopy, confirming that a large part of former topsoil material is already mineralized. On average, the profile based estimate converts to smaller annual loss rates of 2.2 (non-intensive) and 4.8 t CO2−C ha−1a−1 (intensive) management. Our data, together with historical flux measurements at this site, provide evidence that peat decomposition rates increased over time, despite declining organic matter quality. We suggest that higher management intensities (i.e., higher fertilization and changes in carbon export from the field), including drainage, and increased mean annual temperature may be important factors for higher emissions today. These two methods are complementary in terms of time horizon and system boundary and, in conjunction, confirm the long-term emission potential of temperate drained organic grassland soils.
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Soares Ribeiro, Vanessa Soares Ribeiro, Lucas Navarro Paolucci, José Henrique Schoereder, and Ricardo Ribeiro de Castro Solar. "Divergence of Ant Communities Over Time in a Fragmented Atlantic Rain Forest Landscape." Sociobiology 69, no. 3 (September 7, 2022): e8099. http://dx.doi.org/10.13102/sociobiology.v69i3.8099.
Повний текст джерелаАнотація:
Habitat fragmentation changes biological communities and its spatiotemporal dynamics – which may lead to either biotic homogenization or heterogenization along time and space. Both processes can occur by addition, replacement or loss of species within communities, altering compositional similarity across the landscape. We investigated which of these two processes (biotic homogenization or heterogenization) occurs, and its possible underlying mechanism, over 15 years in an Atlantic Forest landscape using ants as model organisms. We sampled ants in 17 forest fragments across three different years, compared their composition similarity, species richness, and species richness of groups classified according to their habitat preferences. We sampled a total of 132 ant species. Ant communities in fragments diverged over time, suggesting they experienced an idiosyncratic structuring process. This biotic heterogenization occurred through an additive process, as ant species richness increased over time, mainly due to an increase of generalist ant species, and a decrease of forest specialist ant species. These changes occurred despite the higher forest cover in the landscape along years. Since different species can perform different functions in ecosystems, this biotic heterogenization may have implications for ecosystem functioning. Investigating how disturbances structure biological communities over time, especially those performing important ecosystem functions, can shed light to our understanding of possible changes in ecosystem functions and consequently for forest regeneration.
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MADAN, DILIP B., MARTIJN PISTORIUS, and WIM SCHOUTENS. "CONIC TRADING IN A MARKOVIAN STEADY STATE." International Journal of Theoretical and Applied Finance 20, no. 02 (March 2017): 1750010. http://dx.doi.org/10.1142/s0219024917500108.
Повний текст джерелаАнотація:
Trading strategies are valued using nonlinear conditional expectations based on concave probability distortions. They are also referred to as expectation with respect to a nonadditive probability. The nonadditive probability attains conservatism by exaggerating upwards the probabilities of tail loss events and simultaneously deflating the probabilities of tail gain events. Fixed points for value and policy iterations are obtained when probabilities are distorted and they fail to exist for classical linear or additive expectations. Illustrations are provided for Markovian systems in one, two and five dimensions. Trading positions are seen to balance prediction rewards against the demands for hedging value functions.
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Ismail, Ismail Hassan, Christi Andrin, Darin McDonald, and Michael J. Hendzel. "BMI1-mediated histone ubiquitylation promotes DNA double-strand break repair." Journal of Cell Biology 191, no. 1 (October 4, 2010): 45–60. http://dx.doi.org/10.1083/jcb.201003034.
Повний текст джерелаАнотація:
Polycomb group (PcG) proteins are major determinants of cell identity, stem cell pluripotency, and epigenetic gene silencing during development. The polycomb repressive complex 1, which contains BMI1, RING1, and RING2, functions as an E3-ubuiquitin ligase. We found that BMI1 and RING2 are recruited to sites of DNA double-strand breaks (DSBs) where they contribute to the ubiquitylation of γ-H2AX. In the absence of BMI1, several proteins dependent on ubiquitin signaling, including 53BP1, BRCA1, and RAP80, are impaired in recruitment to DSBs. Loss of BMI1 sensitizes cells to ionizing radiation to the same extent as loss of RNF8. The simultaneous depletion of both proteins revealed an additive increase in radiation sensitivity. These data uncover an unexpected link between the polycomb and the DNA damage response pathways, and suggest a novel function for BMI1 in maintaining genomic stability.
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Kirchner, Alexander, Burghardt Klöden, Thomas Weißgärber, Bernd Kieback, Achim Schoberth, Daniel Greitemeier, and Sarah Bagehorn. "Mechanical Properties of Ti-6Al-4V Fabricated by Electron Beam Melting." Key Engineering Materials 704 (August 2016): 235–40. http://dx.doi.org/10.4028/www.scientific.net/kem.704.235.
Повний текст джерелаАнотація:
Powder bed additive manufacturing of titanium components offers several advantages. The high freedom of design enables the fabrication of structurally optimized, lightweight parts. Complex geometries may serve additional functions. The use of additive manufacturing has the potential to revolutionize logistics by dramatically reducing lead time and enabling a high degree of customization. Manufacturing near net shape parts reduces the loss of expensive material.For the application in safety relevant parts certainty about static and fatigue strength is critical. A challenge arises from complex influences of built parameters, heat treatments and surface quality. Ti-6Al-4V specimen built by electron beam melting (EBM) were subjected to heat treatments adapted to various employment scenarios. The results of tensile and fatigue testing as well as crack propagation and fractography will be compared to titanium manufactured conventionally and by selective laser melting (SLM). The mechanical behavior will be correlated to the microstructural evolution caused by the heat treatments
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Narendran, Ganesan, Avdhoot Walunj, A. Mohan Kumar, Praveen Jeyachandran, Nasser S. Awwad, Hala A. Ibrahium, M. R. Gorji, and D. Arumuga Perumal. "Experimental Demonstration of Compact Polymer Mass Transfer Device Manufactured by Additive Manufacturing with Hydrogel Integration to Bio-Mimic the Liver Functions." Bioengineering 10, no. 4 (March 26, 2023): 416. http://dx.doi.org/10.3390/bioengineering10040416.
Повний текст джерелаАнотація:
In this paper, we designed and demonstrated a stimuli-responsive hydrogel that mimics the mass diffusion function of the liver. We have controlled the release mechanism using temperature and pH variations. Additive manufacturing technology was used to fabricate the device with nylon (PA-12), using selective laser sintering (SLS). The device has two compartment sections: the lower section handles the thermal management, and feeds temperature-regulated water into the mass transfer section of the upper compartment. The upper chamber has a two-layered serpentine concentric tube; the inner tube carries the temperature-regulated water to the hydrogel using the given pores. Here, the hydrogel is present in order to facilitate the release of the loaded methylene blue (MB) into the fluid. By adjusting the fluid’s pH, flow rate, and temperature, the deswelling properties of the hydrogel were examined. The weight of the hydrogel was maximum at 10 mL/min and decreased by 25.29% to 10.12 g for the flow rate of 50 mL/min. The cumulative MB release at 30 °C increased to 47% for the lower flow rate of 10 mL/min, and the cumulative release at 40 °C climbed to 55%, which is 44.7% more than at 30 °C. The MB release rates considerably increased when the pH dropped from 12 to 8, showing that the lower pH had a major impact on the release of MB from the hydrogel. Only 19% of the MB was released at pH 12 after 50 min, and after that, the release rate remained nearly constant. At higher fluid temperatures, the hydrogels lost approximately 80% of their water in just 20 min, compared to a loss of 50% of their water at room temperature. The outcomes of this study may contribute to further developments in artificial organ design.
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Hu, Huan, Ming Tao Zhou, and Xu Dong Hu. "Development of Composite Antifreeze to Ecological Slope Protection Substrate." Advanced Materials Research 827 (October 2013): 355–59. http://dx.doi.org/10.4028/www.scientific.net/amr.827.355.
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Referring to the antifreeze improved test of cement-soil and combining with its own characteristics and functions of the ecological slope protection material, the paper selects palm fiber, silicon powder and surface active agent as the antifreeze raw materials to the ecological slope protection substrate. Based on the method of antifreeze on concrete, through the evaluation of relative dynamic elastic modulus and mass loss rates in the process of freeze-thaw cycles, the results show that the best composite antifreeze to improve the frost resistance property of the ecological slope protection substrate is that palm fiber: silicon powder: surface active agent=1:3:0.05. While the additive amount reaches 1.5% by weight of the dry ecological slope protection substrate, the best effect will be obtained.
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Nord-Larsen, Thomas, Henrik Meilby, and Jens Peter Skovsgaard. "Simultaneous estimation of biomass models for 13 tree species: effects of compatible additivity requirements." Canadian Journal of Forest Research 47, no. 6 (June 2017): 765–76. http://dx.doi.org/10.1139/cjfr-2016-0430.
Повний текст джерелаАнотація:
A desirable feature of biomass models distinguishing different tree components is compatible additivity of the component functions. Due to forcing of parameter estimates, such additivity is achieved at an expense of precision of the component functions. This study aimed to analyse the loss of precision incurred by forcing of parameters in tree biomass models due to (i) additivity constraints, (ii) combining global and species-specific parameters, and (iii) estimating component functions simultaneously as a system instead of as individual equations. Based on biomass data from 697 trees including 13 different species, we estimated a set of compatibly additive, nonlinear biomass models using simultaneous estimation and compared these with less restricted model systems. In line with other similar studies, the overall model system explained 88%–99% of the variation in individual biomass components. Compared with the unrestricted model, restricting parameters to obtain compatible additivity resulted in a change in RMSE of –0.6% to 5.4%. When restricting parameter estimates using both species-specific and global parameters, RMSE increased by 1.7%–13.1%. Estimating model parameters using simultaneous estimation (nonlinear iterated seemingly unrelated regression, NSUR) increased model bias compared with ordinary least squares estimation (OLS) for most biomass components. Contrary to expectations, NSUR estimation did not lead to a reduction in the standard error of estimates.
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Savischenko, N. V., and E. V. Lebeda. "Multi-position signal coherent reception error probability in a channel with generalized gamma or K fading and white noise." Information and Control Systems, no. 1 (February 19, 2019): 76–88. http://dx.doi.org/10.31799/1684-8853-2019-1-76-88.
Повний текст джерелаАнотація:
Introduction:One of the main problems in communication theory is giving definitions to such characteristics of an information transmission system as noise immunity (error probability) and transfer rate. Their knowledge allows you to determine the transmitted information quality and quantity, respectively. The calculation of the error probability for a communications channel (for example, with fading) allows you to estimate the loss or gain in noise immunity with modems of various signal designs.Purpose:Developing a technique for calculating the probability of a bit error with coherent reception of signals in a communication channel with additive white Gaussian noise and general (non-selective in terms of frequency) fading described by gamma distribution orKdistribution (called gamma fading andKfading respectively).Results:The obtained relations allow you to calculate the reception noise immunity in arbitrary twodimensional signaling designs for a communication channel with gamma orKfading and additive white Gaussian noise. Examples are given of bit error probability calculation for phase modulation and quadrature-amplitude modulation signals. The calculation of error probability in a channel with fading for two different distribution laws was reduced to a new special function which is an integral of the product of Tricomi function and an algebraic function. This allowed us to develop a universal mathematical approach valid for both variants of fading. To calculate the new special function introduced in the article and its representation through the known functions, we used both classical hypergeometric functions and a generalized hypergeometric functions of two variables which is Kampé de Fériet function.Practical relevance:When using multi-position signal structures in new telecommunication standards, this technique allows you to obtain an estimate of their potential noise immunity, objectively comparing signal constructions and correctly choosing the best options for new modem developer.
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Timakov, Benjamin, and Ping Zhang. "Genetic Analysis of a Y-Chromosome Region That Induces Triplosterile Phenotypes and Is Essential for Spermatid Individualization in Drosophila melanogaster." Genetics 155, no. 1 (May 1, 2000): 179–89. http://dx.doi.org/10.1093/genetics/155.1.179.
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Abstract The heterochromatic Y chromosome of Drosophila melanogaster contains ~40 Mb of DNA but has only six loci mutable to male sterility. Region h1-h9 on YL, which carries the kl-3 and kl-5 loci, induces male sterility when present in three copies. We show that three separate segments within the region are responsible for the triplosterility and have an additive effect on male fertility. The triplosterile males displayed pleiotropic defects, beginning at early postmeiotic stages. However, the triplosterility was unaffected by kl-3 or kl-5 alleles. These data suggest that region h1-h9 is complex and may contain novel functions in addition to those of the previously identified kl-3 and kl-5 loci. The kl-3 and kl-5 mutations as well as deficiencies within region h1-h9 result in loss of the spermatid axonemal outer dynein arms. Examination using fluorescent probes showed that males deficient for h1-h3 or h4-h9 displayed a postmeiotic lesion with disrupted individualization complexes scattered along the spermatid bundle. In contrast, the kl-3 and kl-5 mutations had no effect on spermatid individualization despite the defect in the axonemes. These results demonstrate that region h1-h9 carries genetically separable functions: one required for spermatid individualization and the other essential for assembling the axonemal dynein arms.
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Li, Jun-yi, and Jian-hua Li. "Fast Image Search with Locality-Sensitive Hashing and Homogeneous Kernels Map." Scientific World Journal 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/350676.
Повний текст джерелаАнотація:
Fast image search with efficient additive kernels and kernel locality-sensitive hashing has been proposed. As to hold the kernel functions, recent work has probed methods to create locality-sensitive hashing, which guarantee our approach’s linear time; however existing methods still do not solve the problem of locality-sensitive hashing (LSH) algorithm and indirectly sacrifice the loss in accuracy of search results in order to allow fast queries. To improve the search accuracy, we show how to apply explicit feature maps into the homogeneous kernels, which help in feature transformation and combine it with kernel locality-sensitive hashing. We prove our method on several large datasets and illustrate that it improves the accuracy relative to commonly used methods and make the task of object classification and, content-based retrieval more fast and accurate.
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Wong, Alex, Mukund Mundhra, and Stefano Soatto. "Stereopagnosia: Fooling Stereo Networks with Adversarial Perturbations." Proceedings of the AAAI Conference on Artificial Intelligence 35, no. 4 (May 18, 2021): 2879–88. http://dx.doi.org/10.1609/aaai.v35i4.16394.
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We study the effect of adversarial perturbations of images on the estimates of disparity by deep learning models trained for stereo. We show that imperceptible additive perturbations can significantly alter the disparity map, and correspondingly the perceived geometry of the scene. These perturbations not only affect the specific model they are crafted for, but transfer to models with different architecture, trained with different loss functions. We show that, when used for adversarial data augmentation, our perturbations result in trained models that are more robust, without sacrificing overall accuracy of the model. This is unlike what has been observed in image classification, where adding the perturbed images to the training set makes the model less vulnerable to adversarial perturbations, but to the detriment of overall accuracy. We test our method using the most recent stereo networks and evaluate their performance on public benchmark datasets.
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Gobal, Arash, and Bahram Ravani. "An Adaptive Discrete Element Method for Physical Modeling of the Selective Laser Sintering Process." Applied Mechanics and Materials 869 (August 2017): 69–84. http://dx.doi.org/10.4028/www.scientific.net/amm.869.69.
Повний текст джерелаАнотація:
Selective Laser Sintering (SLS) has recently become one of the fastest growing additive manufacturing processes due to its capability of fabricating metal parts with high dimensional accuracy and surface quality. Physical modeling of this process plays an important role in properly controlling the process parameters of the process. In this paper, we present a 3 dimensional, adaptive discrete element method for simulation of the SLS process on personal computers. The presented method models the laser-powder interaction at particle level, achieving high simulation accuracy while adaptively increasing the discrete element size as local temperatures drop inside the powder bed for improved efficiency. Numerical shape functions are developed for calculating individual particle temperatures at any point during the simulation. Results show that this physical model improves the runtime significantly in virtual simulation of SLS process without loss of simulation accuracy.
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Hu, Chaofang, Zelong Zhang, Xianpeng Zhou, and Na Wang. "Command filter-based fuzzy adaptive nonlinear sensor-fault tolerant control for a quadrotor unmanned aerial vehicle." Transactions of the Institute of Measurement and Control 42, no. 2 (August 9, 2019): 198–213. http://dx.doi.org/10.1177/0142331219865377.
Повний текст джерелаАнотація:
In this paper, a novel asymptotic fuzzy adaptive nonlinear fault tolerant control (FTC) scheme is presented for the under-actuated dynamics of a quadrotor unmanned aerial vehicle (UAV) subject to diverse sensor faults. The proposed FTC approach can deal with both additive sensor faults (bias, drift, loss of accuracy) and multiplicative sensor fault (loss of effectiveness). The overall dynamics is separated into position loop and attitude loop for FTC controllers design. Combining uncertain parameters and external disturbances, the four types of faults occurring in velocity sensors and Euler angle rate sensors are transformed equivalently into the unknown nonlinear function vectors and uncertain control gains. Fuzzy logic systems are used to approximate the lumped nonlinear functions, and adaptive parameters are estimated online. Nussbaum technique is introduced to deal with the unknown control gains. For both control loops, FTC controllers are designed via command filter-based backstepping approach, in which sliding mode control is introduced to establish asymptotic stability. All tracking error signals of the closed-loop control system are proved to converge to zero asymptotically. Finally, simulation comparisons with other methods demonstrate the effectiveness of the proposed FTC approach for quadrotor UAV with sensor faults.
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Alirezazadeh, Pendar, Fadi Dornaika, and Abdelmalik Moujahid. "Deep Learning with Discriminative Margin Loss for Cross-Domain Consumer-to-Shop Clothes Retrieval." Sensors 22, no. 7 (March 30, 2022): 2660. http://dx.doi.org/10.3390/s22072660.
Повний текст джерелаАнотація:
Consumer-to-shop clothes retrieval refers to the problem of matching photos taken by customers with their counterparts in the shop. Due to some problems, such as a large number of clothing categories, different appearances of clothing items due to different camera angles and shooting conditions, different background environments, and different body postures, the retrieval accuracy of traditional consumer-to-shop models is always low. With advances in convolutional neural networks (CNNs), the accuracy of garment retrieval has been significantly improved. Most approaches addressing this problem use single CNNs in conjunction with a softmax loss function to extract discriminative features. In the fashion domain, negative pairs can have small or large visual differences that make it difficult to minimize intraclass variance and maximize interclass variance with softmax. Margin-based softmax losses such as Additive Margin-Softmax (aka CosFace) improve the discriminative power of the original softmax loss, but since they consider the same margin for the positive and negative pairs, they are not suitable for cross-domain fashion search. In this work, we introduce the cross-domain discriminative margin loss (DML) to deal with the large variability of negative pairs in fashion. DML learns two different margins for positive and negative pairs such that the negative margin is larger than the positive margin, which provides stronger intraclass reduction for negative pairs. The experiments conducted on publicly available fashion datasets DARN and two benchmarks of the DeepFashion dataset—(1) Consumer-to-Shop Clothes Retrieval and (2) InShop Clothes Retrieval—confirm that the proposed loss function not only outperforms the existing loss functions but also achieves the best performance.
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Barrow, J. R., and M. R. Capecchi. "Compensatory defects associated with mutations in Hoxa1 restore normal palatogenesis to Hoxa2 mutants." Development 126, no. 22 (November 15, 1999): 5011–26. http://dx.doi.org/10.1242/dev.126.22.5011.
Повний текст джерелаАнотація:
The rhombencephalic neural crest play several roles in craniofacial development. They give rise to the cranial sensory ganglia and much of the craniofacial skeleton, and are vital for patterning of the craniofacial muscles. The loss of Hoxa1 or Hoxa2 function affects the development of multiple neural crest-derived structures. To understand how these two genes function together in craniofacial development, an allele was generated that disrupts both of these linked genes. Some of the craniofacial defects observed in the double mutants were additive combinations of those that exist in each of the single mutants, indicating that each gene functions independently in the formation of these structures. Other defects were found only in the double mutants demonstrating overlapping or synergistic functions. We also uncovered multiple defects in the attachments and trajectories of the extrinsic tongue and hyoid muscles in Hoxa2 mutants. Interestingly, the abnormal trajectory of two of these muscles, the styloglossus and the stylohyoideus, blocked the attachment of the hyoglossus to the greater horn of the hyoid, which in turn correlated exactly with the presence of cleft palate in Hoxa2 mutants. We suggest that the hyoglossus, whose function is to depress the lateral edges of the tongue, when unable to make its proper attachment to the greater horn of the hyoid, forces the tongue to adopt an abnormal posture which blocks closure of the palatal shelves. Unexpectedly, in Hoxa1/Hoxa2 double mutants, the penetrance of cleft palate is dramatically reduced. We show that two compensatory defects, associated with the loss of Hoxa1 function, restore normal attachment of the hyoglossus to the greater horn thereby allowing the palatal shelves to lift and fuse above the flattened tongue.
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Kawase, Yasushi, and Hanna Sumita. "Randomized Strategies for Robust Combinatorial Optimization." Proceedings of the AAAI Conference on Artificial Intelligence 33 (July 17, 2019): 7876–83. http://dx.doi.org/10.1609/aaai.v33i01.33017876.
Повний текст джерелаАнотація:
In this paper, we study the following robust optimization problem. Given an independence system and candidate objective functions, we choose an independent set, and then an adversary chooses one objective function, knowing our choice. The goal is to find a randomized strategy (i.e., a probability distribution over the independent sets) that maximizes the expected objective value in the worst case. This problem is fundamental in wide areas such as artificial intelligence, machine learning, game theory and optimization. To solve the problem, we propose two types of schemes for designing approximation algorithms. One scheme is for the case when objective functions are linear. It first finds an approximately optimal aggregated strategy and then retrieves a desired solution with little loss of the objective value. The approximation ratio depends on a relaxation of an independence system polytope. As applications, we provide approximation algorithms for a knapsack constraint or a matroid intersection by developing appropriate relaxations and retrievals. The other scheme is based on the multiplicative weights update (MWU) method. The direct application of the MWU method does not yield a strict multiplicative approximation algorithm but yield one with an additional additive error term. A key technique to overcome the issue is to introduce a new concept called (η,γ)-reductions for objective functions with parameters η and γ. We show that our scheme outputs a nearly α-approximate solution if there exists an α-approximation algorithm for a subproblem defined by (η,γ)-reductions. This improves approximation ratios in previous results. Using our result, we provide approximation algorithms when the objective functions are submodular or correspond to the cardinality robustness for the knapsack problem.
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Alam, Aafreen. "Reduction of Speckle Noise in SAR Images With Hybrid Wavelet Filter." International Journal for Research in Applied Science and Engineering Technology 10, no. 7 (July 31, 2022): 4834–39. http://dx.doi.org/10.22214/ijraset.2022.46014.
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Abstract: Images produced by synthetic aperture radar (SAR) are crucial for observing and visualizing situations. However, speckle noise makes it difficult to assess SAR images since it reduces image quality and leads to incorrect interpretation. Multiplicative noise features can be found in speckle noise. For the past few years, experts have concentrated on despeckling or speckle reduction. However, the majority of the current efforts showed a loss of edge information. Since wavelet transform and bivariate shrinkage functions have many advantages, this study is devoted to designing a method for speckle removal. After performing a logarithmic transformation to turn multiplicative noise into additive noise, the suggested approach next applies a Lee filter. Then, a wavelet transform was used to breakdown the filtered image. Prior to applying the median filter, the bivariate shrinkage function was used to estimate each coefficient. The simulation results demonstrate that the suggested approach outperforms previous work and several traditional methods
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Luo, Man, Li-Ke Jiang, Yao-Xiong Huang, Ming Xiao, Bo Li, and Guo-Lin Zou. "Effects of Citral on Aspergillus flavus Spores by Quasi-elastic Light Scattering and Multiplex Microanalysis Techniques." Acta Biochimica et Biophysica Sinica 36, no. 4 (April 1, 2004): 277–83. http://dx.doi.org/10.1093/abbs/36.4.277.
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Abstract Citral refined from Litsea cubeba oil has been found to have a strong influence on fungi, especially Aspergillus flavus. Multiplex microanalysis and quasi-elastic light scattering techniques were applied to study the effects of citral on Aspergillus flavus spores from the levels of membrane, organelle and intracellular macromolecule. It was found that citral injured the wall and the membrane of A. flavus spore, resulting in decrease of its elasticity. After entering the cell, citral not only influenced the genetic expression of mitochondrion reduplication and its morphology, but also changed the aggregation of protein-like macromolecules. As a result, cells, organelles and macromolecules lost their normal structures and functions, eventually leading to the loss of germination ability of A. flavus spores. Since Litsea cubeba oil as food additive and antifungal agent is safe and less poisonous, it is important to elucidate the inhibitory mechanisms of Litsea cubeba oil on the germination ability of A. flavus spore.
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Zolotavkin, Yevhen, and Martti Juhola. "A New QIM-Based Watermarking Method Robust to Gain Attack." International Journal of Digital Multimedia Broadcasting 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/910808.
Повний текст джерелаАнотація:
We propose a new watermarking method based on quantization index modulation. A concept of initial data loss is introduced in order to increase capacity of the watermarking channel under high intensity additive white Gaussian noise. According to the concept some samples in predefined positions are ignored even though this produces errors in the initial stage of watermark embedding. The proposed method also exploits a new form of distribution of quantized samples where samples that interpret “0” and “1” have differently shaped probability density functions. Compared to well-known watermarking schemes, this provides an increase of capacity under noise attack and introduces a distinctive feature. Two criteria are proposed that express the feature numerically. The criteria are utilized by a procedure for estimation of a gain factor after possible gain attack. Several state-of-the-art quantization-based watermarking methods were used for comparison on a set of natural grayscale images. The superiority of the proposed method has been confirmed for different types of popular attacks.
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Manfreda, S., and M. Fiorentino. "A stochastic approach for the description of the water balance dynamics in a river basin." Hydrology and Earth System Sciences 12, no. 5 (September 17, 2008): 1189–200. http://dx.doi.org/10.5194/hess-12-1189-2008.
Повний текст джерелаАнотація:
Abstract. The present paper introduces an analytical approach for the description of the soil water balance dynamics over a schematic river basin. The model is based on a stochastic differential equation where the rainfall forcing is interpreted as an additive noise in the soil water balance. This equation can be solved assuming known the spatial distribution of the soil moisture over the basin transforming the two-dimensional problem in space in a one dimensional one. This assumption is particularly true in the case of humid and semihumid environments, where spatial redistribution becomes dominant producing a well defined soil moisture pattern. The model allowed to derive the probability density function of the saturated portion of a basin and of its relative saturation. This theory is based on the assumption that the soil water storage capacity varies across the basin following a parabolic distribution and the basin has homogeneous soil texture and vegetation cover. The methodology outlined the role played by the soil water storage capacity distribution of the basin on soil water balance. In particular, the resulting probability density functions of the relative basin saturation were found to be strongly controlled by the maximum water storage capacity of the basin, while the probability density functions of the relative saturated portion of the basin are strongly influenced by the spatial heterogeneity of the soil water storage capacity. Moreover, the saturated areas reach their maximum variability when the mean rainfall rate is almost equal to the soil water loss coefficient given by the sum of the maximum rate of evapotranspiration and leakage loss in the soil water balance. The model was tested using the results of a continuous numerical simulation performed with a semi-distributed model in order to validate the proposed theoretical distributions.
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Cribbs, Sushma K., Kristina Crothers, and Alison Morris. "Pathogenesis of HIV-Related Lung Disease: Immunity, Infection, and Inflammation." Physiological Reviews 100, no. 2 (April 1, 2020): 603–32. http://dx.doi.org/10.1152/physrev.00039.2018.
Повний текст джерелаАнотація:
Despite anti-retroviral therapy (ART), human immunodeficiency virus-1 (HIV)-related pulmonary disease continues to be a major cause of morbidity and mortality for people living with HIV (PLWH). The spectrum of lung diseases has changed from acute opportunistic infections resulting in death to chronic lung diseases for those with access to ART. Chronic immune activation and suppression can result in impairment of innate immunity and progressive loss of T cell and B cell functionality with aberrant cytokine and chemokine responses systemically as well as in the lung. HIV can be detected in the lungs of PLWH and has profound effects on cellular immune functions. In addition, HIV-related lung injury and disease can occur secondary to a number of mechanisms including altered pulmonary and systemic inflammatory pathways, viral persistence in the lung, oxidative stress with additive effects of smoke exposure, microbial translocation, and alterations in the lung and gut microbiome. Although ART has had profound effects on systemic viral suppression in HIV, the impact of ART on lung immunology still needs to be fully elucidated. Understanding of the mechanisms by which HIV-related lung diseases continue to occur is critical to the development of new preventive and therapeutic strategies to improve lung health in PLWH.
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Veerkamp, R. F., and R. Thompson. "Multi-trait covariance functions to estimate genetic correlations between milk yield, dry-matter intake and live weight during lactation." BSAP Occasional Publication 24 (1999): 147–51. http://dx.doi.org/10.1017/s1463981500043168.
Повний текст джерелаАнотація:
AbstractEnergy balance is a function of dry-matter intake (DMI), live weight and milk yield over a certain time period. To investigate potential strategies to use genetic selection for the improvement of the negative energy balance, genetic co-variances were estimated among DMI, live weight and milk yield during the first 15 weeks of lactation (no.=628). Rather than estimating the full 45 by 45 matrix a random regression model was used to estimate a second order covariance functions for the additive genetic and permanent environmental effects. Fixed effects were test-day, a group effect and week in lactation. Estimates for the genetic covariance function demonstrated that a high level of milk yield is only moderately correlated with a high level of DMI (0.21) but very strongly correlated to an increase of intake (0.97) and a loss of live weight (-0.46) during the first 15 weeks of lactation. Levels of weight and intake were correlated strongly (0.81). Estimates for the genetic correlations between weeks 1 and 15 were 0.79, 0.34 and 0.83 for milk yield, DMI and live weight respectively. DMI during early lactation was negatively correlated with milk yield but DMI during the later weeks was positively correlated with milk yield. The implication is that when selection is for a linear combination of milk yield, DMI and live weight (i.e. energy balance or efficiency) the moment in lactation of measuring each trait on the cow is of importance
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Huang, Fangyi, Hua Su, and Xiaoli Tang. "Microwave dielectric properties of Na+-substituted CaMg0.9Li0.2Si2O6 ceramics." MATEC Web of Conferences 355 (2022): 01024. http://dx.doi.org/10.1051/matecconf/202235501024.
Повний текст джерелаАнотація:
Ceramics with low dielectric constant are widely used in high frequency substrates. The low temperature sintered CaMg0.9-xNa2xLi0.2Si2O6(x = 0–0.05 and 0.1) ceramics with low dielectric constant and dielectric loss were prepared by the traditional solid-state reaction method, with 0.5wt%LBSCA additive. The XRD patterns of the samples were obtained by X-ray diffraction and it was found that there were three ceramic components, CaMgSi2O6, CaSiO3 and Na2MgSiO4, which indicated that the experimental sample was a multiphase ceramic system. Through the trend of bulk density as functions of the content of substitution and the change of SEM morphology, it could be found that appropriate amount of Na+ substitution can promote the grain growing and the densification of ceramics. Results demonstrated that both the Q × f and εr were relevant to bulk density and the second phase. The τf was also affected by the second phase to some extent. In particular, the ceramics sintered at 925 °C for 3h possessed the desirable microwave dielectric properties for LTCC application: εr = 7.03, Q × f = 17,956 GHz, and τf= −79 ppm/°C.
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Newbold, Tim. "Future effects of climate and land-use change on terrestrial vertebrate community diversity under different scenarios." Proceedings of the Royal Society B: Biological Sciences 285, no. 1881 (June 20, 2018): 20180792. http://dx.doi.org/10.1098/rspb.2018.0792.
Повний текст джерелаАнотація:
Land-use and climate change are among the greatest threats facing biodiversity, but understanding their combined effects has been hampered by modelling and data limitations, resulting in part from the very different scales at which land-use and climate processes operate. I combine two different modelling paradigms to predict the separate and combined (additive) effects of climate and land-use change on terrestrial vertebrate communities under four different scenarios. I predict that climate-change effects are likely to become a major pressure on biodiversity in the coming decades, probably matching or exceeding the effects of land-use change by 2070. The combined effects of both pressures are predicted to lead to an average cumulative loss of 37.9% of species from vertebrate communities under ‘business as usual’ (uncertainty ranging from 15.7% to 54.2%). Areas that are predicted to experience the effects of both pressures are concentrated in tropical grasslands and savannahs. The results have important implications for the conservation of biodiversity in future, and for the ability of biodiversity to support important ecosystem functions, upon which humans rely.
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Kubicek, Penhaker, Augustynek, Cerny, and Oczka. "Segmentation of Articular Cartilage and Early Osteoarthritis based on the Fuzzy Soft Thresholding Approach Driven by Modified Evolutionary ABC Optimization and Local Statistical Aggregation." Symmetry 11, no. 7 (July 2, 2019): 861. http://dx.doi.org/10.3390/sym11070861.
Повний текст джерелаАнотація:
Articular cartilage assessment, with the aim of the cartilage loss identification, is a crucial task for the clinical practice of orthopedics. Conventional software (SW) instruments allow for just a visualization of the knee structure, without post processing, offering objective cartilage modeling. In this paper, we propose the multiregional segmentation method, having ambitions to bring a mathematical model reflecting the physiological cartilage morphological structure and spots, corresponding with the early cartilage loss, which is poorly recognizable by the naked eye from magnetic resonance imaging (MRI). The proposed segmentation model is composed from two pixel’s classification parts. Firstly, the image histogram is decomposed by using a sequence of the triangular fuzzy membership functions, when their localization is driven by the modified artificial bee colony (ABC) optimization algorithm, utilizing a random sequence of considered solutions based on the real cartilage features. In the second part of the segmentation model, the original pixel’s membership in a respective segmentation class may be modified by using the local statistical aggregation, taking into account the spatial relationships regarding adjacent pixels. By this way, the image noise and artefacts, which are commonly presented in the MR images, may be identified and eliminated. This fact makes the model robust and sensitive with regards to distorting signals. We analyzed the proposed model on the 2D spatial MR image records. We show different MR clinical cases for the articular cartilage segmentation, with identification of the cartilage loss. In the final part of the analysis, we compared our model performance against the selected conventional methods in application on the MR image records being corrupted by additive image noise.
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Monge, I., R. Krishnamurthy, D. Sims, F. Hirth, M. Spengler, L. Kammermeier, H. Reichert, and P. J. Mitchell. "Drosophila transcription factor AP-2 in proboscis, leg and brain central complex development." Development 128, no. 8 (April 15, 2001): 1239–52. http://dx.doi.org/10.1242/dev.128.8.1239.
Повний текст джерелаАнотація:
We report loss- and gain-of-function analyses that identify essential roles in development for Drosophila transcription factor AP-2. A mutagenesis screen yielded 16 lethal point mutant alleles of dAP-2. Null mutants die as adults or late pupae with a reduced proboscis, severely shortened legs (~30% of normal length) lacking tarsal joints, and disruptions in the protocerebral central complex, a brain region critical for locomotion. Seven hypomorphic alleles constitute a phenotypic series yielding hemizygous adults with legs ranging from 40–95% of normal length. Hypomorphic alleles show additive effects with respect to leg length and viability; and several heteroallelic lines were established. Heteroallelic adults have moderately penetrant defects that include necrotic leg joints and ectopic growths (sometimes supernumerary antennae) invading medial eye territory. Several dAP-2 alleles with DNA binding domain missense mutations are null in hemizygotes but have dominant negative effects when paired with hypomorphic alleles. In wild-type leg primordia, dAP-2 is restricted to presumptive joints. Ectopic dAP-2 in leg discs can inhibit but not enhance leg elongation indicating that functions of dAP-2 in leg outgrowth are region restricted. In wing discs, ectopic dAP-2 cell autonomously transforms presumptive wing vein epithelium to ectopic sensory bristles, consistent with an instructive role in sensory organ development. These findings reveal multiple functions for dAP-2 during morphogenesis of feeding and locomotor appendages and their neural circuitry, and provide a new paradigm for understanding AP-2 family transcription factors.
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Sinclair, Sean R., Siddhartha Banerjee, and Christina Lee Yu. "Sequential Fair Allocation." ACM SIGMETRICS Performance Evaluation Review 50, no. 1 (June 20, 2022): 95–96. http://dx.doi.org/10.1145/3547353.3526951.
Повний текст джерелаАнотація:
We consider the problem of dividing limited resources to individuals arriving over T rounds. Each round has a random number of individuals arrive, and individuals can be characterized by their type (i.e. preferences over the different resources). A standard notion of 'fairness' in this setting is that an allocation simultaneously satisfy envy-freeness and efficiency. For divisible resources, when the number of individuals of each type are known upfront, the above desiderata are simultaneously achievable for a large class of utility functions. However, in an online setting when the number of individuals of each type are only revealed round by round, no policy can guarantee these desiderata simultaneously. We show that in the online setting, the two desired properties (envy-freeness and efficiency) are in direct contention, in that any algorithm achieving additive counterfactual envy-freeness up to a factor of LT necessarily suffers a efficiency loss of at least 1 / LT. We complement this uncertainty principle with a simple algorithm, Guarded-Hope, which allocates resources based on an adaptive threshold policy and is able to achieve any fairness-efficiency point on this frontier.
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Witke, Walter, Wei Li, David J. Kwiatkowski, and Frederick S. Southwick. "Comparisons of CapG and gelsolin-null macrophages." Journal of Cell Biology 154, no. 4 (August 20, 2001): 775–84. http://dx.doi.org/10.1083/jcb.200101113.
Повний текст джерелаАнотація:
Capping the barbed ends of actin filaments is a critical step for regulating actin-based motility in nonmuscle cells. The in vivo function of CapG, a calcium-sensitive barbed end capping protein and member of the gelsolin/villin family, has been assessed using a null Capg allele engineered into mice. Both CapG-null mice and CapG/gelsolin double-null mice appear normal and have no gross functional abnormalities. However, the loss of CapG in bone marrow macrophages profoundly inhibits macrophage colony stimulating factor–stimulated ruffling; reintroduction of CapG protein by microinjection fully restores this function. CapG-null macrophages also demonstrate ∼50% impairment of immunoglobulin G, and complement-opsonized phagocytosis and lanthanum-induced vesicle rocketing. These motile functions are not impaired in gelsolin-null macrophages and no additive effects are observed in CapG/gelsolin double-null macrophages, establishing that CapG function is distinct from, and does not overlap with, gelsolin in macrophages. Our observations indicate that CapG is required for receptor-mediated ruffling, and that it is a major functional component of macrophage phagocytosis. These primary effects on macrophage motile function suggest that CapG may be a useful target for the regulation of macrophage-mediated inflammatory responses.
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Su, Shan, Cristina Di Poto, Rabindra Roy, Xuefeng Liu, Wanxing Cui, Alexander Kroemer, and Habtom W. Ressom. "Long-term culture and characterization of patient-derived primary hepatocytes using conditional reprogramming." Experimental Biology and Medicine 244, no. 11 (June 11, 2019): 857–64. http://dx.doi.org/10.1177/1535370219855398.
Повний текст джерелаАнотація:
Cultivation of primary human hepatocytes (PHHs) often faces obstacles including failure of long-term in vitro culture, weak proliferation ability, rapid loss of liver-specific function and morphology, and tendency of fibrosis. Previous research focused on immortalization methods, such as telomerase and viral, to culture immortalized primary human hepatocytes, which may lose some of the normal properties. However, non-immortalized PHHs often fail to maintain long-term viability and functionality. These highlight the urgent need for developing new culture strategy for PHHs. In the present study, we isolated PHHs from fresh human liver tissues representing different liver diseases and age groups. We used conditional reprogramming, without permanent immortalization, for long-term in vitro primary human hepatocytes cultivation and characterization. For functional characterization, we assessed CYP3A4, 1A1 and 2C9 activities and measured the mRNA expression of albumin, s100a4, krt8, krt18, cyp1a1, cyp3a4, cyp2b6, cyp2c8, cyp2c9, and cyp2d6. Additionally, we compared the DNA fingerprint of the cells against their original liver tissues using short tandem repeat (STR) analysis. We found that PHHs-derived from young patients can survive for more than three months, while the lifespan of primary human hepatocytes derived from adult patients ranges from two to three months, which is longer than most commercial primary hepatocytes. Importantly, the cells at early passages retain strong CYP3A4, 1A1 and 2C9 activities and the DNA fingerprints are identical with their original tissues. Through conditional programming, we achieved, for the first time, a high level of success rate in the long-term in vitro cultivation of primary human hepatocytes-derived patients representing diverse liver disease. Moreover, the conditional programming cell culture technology reported in this paper requires neither co-culture with additive cells, nor complex and expensive components, such as collagen sandwich or spheroid culture. We thus believe that the patient-derived PHHs cultivation using conditional programming may provide a viable and valuable cell model to study liver disease-related mechanisms. Impact statement Commercially available primary human hepatocytes rapidly lose their proliferative ability and liver-specific functions over a few cultivation days. The demand for pharmaceutical toxicity screening and liver disease research requires the development of long-term primary hepatocyte culture methods. This manuscript addresses this challenge by introducing for the first time successful long-term in vitro cultivation of primary human hepatocytes from a range of liver transplantation patients using conditional reprogramming technique. The beauty of this technique is that it is not a permanent immortalization and does not require co-culture with additive cells. The primary human hepatocytes retain proliferative capacity, genetic stability, and hepatocyte-specific functions at early passages. In view of these, we believe that scientists and researchers will benefit from using these highly valuable cell models to study diverse liver diseases.