Adversarial training for tabular data with attack propagation

Adversarial attacks are a major concern in security-centered applications, where malicious actors continuously try to mislead Machine Learning (ML) models into wrongly classifying fraudulent activity as legitimate, whereas system maintainers try to stop them. Adversarially training ML models that are robust against such attacks can prevent business losses and reduce the work load of system maintainers. In such applications data is often tabular and the space available for attackers to manipulate undergoes complex feature engineering transformations, to provide useful signals for model training, to a space attackers cannot access. Thus, we propose a new form of adversarial training where attacks are propagated between the two spaces in the training loop. We then test this method empirically on a real world dataset in the domain of credit card fraud detection. We show that our method can prevent about 30% performance drops under moderate attacks and is essential under very aggressive attacks, with a trade-off loss in performance under no attacks smaller than 7%

Using Open Data to Rapidly Benchmark Biomolecular Simulations : Phospholipid Conformational Dynamics

Molecular dynamics (MD) simulations are widely used to monitor time-resolved motions of biomacromolecules, although it often remains unknown how closely the conformational dynamics correspond to those occurring in real life. Here, we used a large set of open-access MD trajectories of phosphatidylcholine (PC) lipid bilayers to benchmark the conformational dynamics in several contemporary MD models (force fields) against nuclear magnetic resonance (NMR) data available in the literature: effective correlation times and spin-lattice relaxation rates. We found none of the tested MD models to fully reproduce the conformational dynamics. That said, the dynamics in CHARMM36 and Slipids are more realistic than in the Amber Lipid14, OPLS-based MacRog, and GROMOS-based Berger force fields, whose sampling of the glycerol backbone conformations is too slow. The performance of CHARMM36 persists when cholesterol is added to the bilayer, and when the hydration level is reduced. However, for conformational dynamics of the PC headgroup, both with and without cholesterol, Slipids provides the most realistic description because CHARMM36 overestimates the relative weight of similar to 1 ns processes in the headgroup dynamics. We stress that not a single new simulation was run for the present work. This demonstrates the worth of open-access MD trajectory databanks for the indispensable step of any serious MD study: benchmarking the available force fields. We believe this proof of principle will inspire other novel applications of MD trajectory databanks and thus aid in developing biomolecular MD simulations into a true computational microscope-not only for lipid membranes but for all biomacromolecular systems.Peer reviewe

Neuropeptide Y inhibits interleukin-1β-induced phagocytosis by microglial cells

<p>Abstract</p> <p>Background</p> <p>Neuropeptide Y (NPY) is emerging as a modulator of communication between the brain and the immune system. However, in spite of increasing evidence that supports a role for NPY in the modulation of microglial cell responses to inflammatory conditions, there is no consistent information regarding the action of NPY on microglial phagocytic activity, a vital component of the inflammatory response in brain injury. Taking this into consideration, we sought to assess a potential new role for NPY as a modulator of phagocytosis by microglial cells.</p> <p>Methods</p> <p>The N9 murine microglial cell line was used to evaluate the role of NPY in phagocytosis. For that purpose, an IgG-opsonized latex bead assay was performed in the presence of lipopolysaccharide (LPS) and an interleukin-1β (IL-1β) challenge, and upon NPY treatment. A pharmacological approach using NPY receptor agonists and antagonists followed to uncover which NPY receptor was involved. Moreover, western blotting and immunocytochemical studies were performed to evaluate expression of p38 mitogen-activated protein kinase (MAPK) and heat shock protein 27 (HSP27), in an inflammatory context, upon NPY treatment.</p> <p>Results</p> <p>Here, we show that NPY inhibits phagocytosis of opsonized latex beads and inhibits actin cytoskeleton reorganization triggered by LPS stimulation. Co-stimulation of microglia with LPS and adenosine triphosphate also resulted in increased phagocytosis, an effect inhibited by an interleukin-1 receptor antagonist, suggesting involvement of IL-1β signaling. Furthermore, direct application of LPS or IL-1β activated downstream signaling molecules, including p38 MAPK and HSP27, and these effects were inhibited by NPY. Moreover, we also observed that the inhibitory effect of NPY on phagocytosis was mediated <it>via </it>Y₁receptor activation.</p> <p>Conclusions</p> <p>Altogether, we have identified a novel role for NPY in the regulation of microglial phagocytic properties, in an inflammatory context.</p

Soil composite-concrete systems : characterization of the geocomposite-soil interface

O conhecimento dos mecanismos de interacção entre solos e geossintéticos é fundamental para o dimensionamento de obras em solo reforçado. Com o objectivo de caracterizar a interface entre um solo e um geossintético, foram realizados ensaios de corte directo e de arranque de um geocompósito drenante disponível no mercado. Os ensaios de corte directo foram realizados em conformidade com a norma NP EN ISO 12957-1:2007. Para a determinação da resistência do geocompósito ao arranque no solo foi concebida e utilizada uma caixa de arranque em laboratório, tendo os ensaios sido realizados de acordo com os procedimentos referidos na norma NP EN 13738:2007.The knowledge of the interaction mechanism between soils and geosynthetics is crucial for the design of construction in reinforced soil. With the purpose of characterising the mechanical behaviour of the interface between a soil and a geosynthetic, direct shear tests and pullout tests were carried out with a geocomposite available in the market. The direct shear tests were performed in compliance with the NP EN ISO 12957-1:2007 standard. For the determination of the pullout resistance of the geocomposite in the soil, a pullout box was conceived and used in the laboratory, and the tests were carried out in accordance with the NP EN 13738:2007 standard

Soil composite-concrete systems : characterization of geocomposite-concrete interface

Com o objectivo de caracterizar mecanicamente a interface entre um geocompósito, disponível no mercado, e um tipo de betão procedeu-se a um programa de ensaios experimentais. Este estudo foi iniciado com a realização de ensaios de determinação das propriedades em tracção do geocompósito, em conformidade com a norma NP EN ISO 10319:2005. A caracterização da ligação entre geocompósito e betão foi efectuada com recurso a ensaios de arranque directo, com diferentes níveis de tensão de confinamento, no sentido de ser obtida a envolvente de rotura da interface. Neste trabalho, a metodologia e os procedimentos adoptados nos diversos ensaios são descritos e os principais resultados obtidos são apresentados e analisados.In order to characterize the mechanical interface between a geocomposite available in the market and a type of concrete, an experimental program was carried out. This study was initiated with a series of tests for the determination of the tensile properties of the geocomposite, according to the NP EN ISO 10319:2005 standard. The characterization of bond between geocomposite and concrete was carried out using direct pullout tests with different levels of confinement, in order to define the yield surface of the interface. In this work the methodology and procedures followed in the different experimental tests are described and the main results are presented and analysed

Histamine stimulates neurogenesis in the rodent subventricular zone

Neural stem/progenitor cells present in the subventricular zone (SVZ) are a potential source of repairing cells after injury. Therefore, the identification of novel players that modulate neural stem cells differentiation can have a huge impact in stem cell-based therapies. Herein, we describe a unique role of histamine in inducing functional neuronal differentiation from cultured mouse SVZ stem/progenitor cells. This proneurogenic effect depends on histamine 1 receptor activation and involves epigenetic modifications and increased expression of Mash1, Dlx2, and Ngn1 genes. Biocompatible poly (lactic-co-glycolic acid) microparticles, engineered to release histamine in a controlled and prolonged manner, also triggered robust neuronal differentiation in vitro. Preconditioning with histamine-loaded microparticles facilitated neuronal differentiation of SVZ-GFP cells grafted in hippocampal slices and in in vivo rodent brain. We propose that neuronal commitment triggered by histamine per se or released from biomaterial-derived vehicles may represent a new tool for brain repair strategies. STEM CELLS 2012; 30:773784Fundacao para a Ciencia e a Tecnologia-Portugal [SFRH/BD/42848/2008, SFRH/BPD/34841/2007, PTDC/SAU-NEU/104415/2008, PTDC/SAU-NEU/101783/2008, PTDC/CTM/099659/2008]; Fundacao Calouste Gulbenkian [96542]info:eu-repo/semantics/publishedVersio

Lightweight Automated Feature Monitoring for Data Streams

Monitoring the behavior of automated real-time stream processing systems has become one of the most relevant problems in real world applications. Such systems have grown in complexity relying heavily on high dimensional input data, and data hungry Machine Learning (ML) algorithms. We propose a flexible system, Feature Monitoring (FM), that detects data drifts in such data sets, with a small and constant memory footprint and a small computational cost in streaming applications. The method is based on a multi-variate statistical test and is data driven by design (full reference distributions are estimated from the data). It monitors all features that are used by the system, while providing an interpretable features ranking whenever an alarm occurs (to aid in root cause analysis). The computational and memory lightness of the system results from the use of Exponential Moving Histograms. In our experimental study, we analyze the system's behavior with its parameters and, more importantly, show examples where it detects problems that are not directly related to a single feature. This illustrates how FM eliminates the need to add custom signals to detect specific types of problems and that monitoring the available space of features is often enough.Comment: 10 pages, 5 figures. AutoML, KDD22, August 14-17, 2022, Washington, DC, U