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A fundamental task in formal concept analysis is the enumeration of formal concepts. Among the fastest algorithms for this task belong algorithms which are based on Close-by-One (CbO), a tree recursive algorithm using lexicographical order of formal concepts to ensure that each formal concept is enumerated exactly once. State-of-the-art algorithms based on CbO, e.g. FCbO, In-Close4, and In-Close5, employ several techniques, which we call pruning, to avoid some unnecessary computations. However, the number of the formal concepts can be exponential w.r.t. dimension of the input data. Therefore, the algorithms do not scale well and large datasets become intractable. To resolve this weakness, several parallel and distributed algorithms were proposed. We propose four new CbO-based algorithms intended for Apache Spark or a similar programming model and show how the pruning can be incorporated into them. We experimentally evaluate the impact of the pruning and demonstrate the scalability of the new algorithms. [ABSTRACT FROM AUTHOR]

N -methyl-D-aspartate receptors (NMDARs) play a significant role in developing several central nervous system (CNS) disorders. Currently, memantine, used for treating Alzheimer's disease, and ketamine, known for its anesthetic and antidepressant properties, are two clinically used NMDAR open-channel blockers. However, despite extensive research into NMDAR modulators, many have shown either harmful side effects or inadequate effectiveness. For instance, dizocilpine (MK-801) is recognized for its powerful psychomimetic effects due to its high-affinity and nearly irreversible inhibition of the GluN1/GluN2 NMDAR subtypes. Unlike ketamine, memantine and MK-801 also act through a unique, low-affinity "membrane-to-channel inhibition" (MCI). We aimed to develop an open-channel blocker based on MK-801 with distinct inhibitory characteristics from memantine and MK-801. Our novel compound, K2060, demonstrated effective voltage-dependent inhibition in the micromolar range at key NMDAR subtypes, GluN1/GluN2A and GluN1/GluN2B, even in the presence of Mg2+. K2060 showed reversible inhibitory dynamics and a partially trapping open-channel blocking mechanism with a significantly stronger MCI than memantine. Using hippocampal slices, 30 µM K2060 inhibited excitatory postsynaptic currents in CA1 hippocampal neurons by ∼51 %, outperforming 30 µM memantine (∼21 % inhibition). K2060 exhibited No Observed Adverse Effect Level (NOAEL) of 15 mg/kg upon intraperitoneal administration in mice. Administering K2060 at a 10 mg/kg dosage resulted in brain concentrations of approximately 2 µM, with peak concentrations (Tmax) achieved within 15 minutes. Finally, applying K2060 with trimedoxime and atropine in mice exposed to tabun improved treatment outcomes. These results underscore K2060's potential as a therapeutic agent for CNS disorders linked to NMDAR dysfunction. [Display omitted] • Both memantine and K2060 exhibit a "partial trapping" blocking mechanism at NMDARs. • K2060 inhibits NMDARs more potently but with slower kinetics compared to memantine. • K2060 demonstrates stronger membrane-to-channel inhibition than memantine. • K2060 effectively crosses the blood-brain barrier and has a NOAEL of 15 mg/kg. • K2060 with trimedoxime+atropine enhances survival in tabun poisoning. [ABSTRACT FROM AUTHOR]

Two recently published algorithms for computation of formal concepts are analyzed. The first algorithm, by Ma et al. (2016), is claimed to provide a new and efficient algorithm for generating all object-oriented concepts. We recall that the generating of all object-oriented concepts and generating of all standard concepts is basically the same problem, since the object-oriented case and the standard case are easily reducible to each other via the set complement. Taking this reducibility into account, Ma et al. merely repeat results by Qian and Wei (2014). The algorithm is not efficient due to its exponential space complexity. Furthermore, we show that the space complexity can be significantly improved by a simple tweak. The algorithm then becomes equivalent to Chein's algorithm, initially published in 1969. The second analyzed algorithm was published by Singh (2017), who proposes an extension of Formal Concept Analysis which handles vague (fuzzy interval valued) data and provides a method for computation of the associated concept lattice. We show that the same extension has been proposed before by Djouadi and Prade in 2009; that the proposed algorithm is incorrect and that it becomes an already known algorithm when we fix it. Additionally, we fix multiple errors in information about related literature committed by Singh. [ABSTRACT FROM AUTHOR]

Mao (Soft Computing 21(24):7293–7311, 2017) claims to make contributions to the study of reduction in attributes in concept lattices by using graph theory. Some of her results could affect development of formal concept analysis; in particular, her three new algorithms for formal concept enumeration promise a lesser time complexity. Unfortunately, as we show, all the three algorithms are incorrect. [ABSTRACT FROM AUTHOR]

We present a reduction theorem which relates sets of fixpoints of fuzzy closure operators to sets of fixpoints of ordinary closure operators. As a result we obtain a method to compute sets of fixpoints of fuzzy closure operators by algorithms available for ordinary operators. We also provide explicit descriptions of selected algorithms which result from the presented approach. [ABSTRACT FROM AUTHOR]

Abstract Singh (2018) claims to propose an extension of formal concept analysis for handling multi-polar information. For this setting he invents an algorithm. The aim of this note is two-fold: First, we show that Singh's algorithm is inefficient, since it is a direct generalization of one of the least efficient algorithms known in formal concept analysis, and strictly speaking, the algorithm is incorrect. Second, we are reminded that many algorithms already exist which can be used instead. This is because Singh's setting is already covered by a more general and well established framework of formal fuzzy concept analysis. [ABSTRACT FROM AUTHOR]

Binary variables classify into two types: asymmetric variables, where one state (1 or 0) is significantly more valuable than the other, and symmetric variables, where both states are equally valuable. Boolean matrix factorization (BMF), a popular methodology of preprocessing and analyzing tabular binary data, handles its input as asymmetric variables. In the paper, we develop an alternative that handles Boolean matrices as symmetric variables. Our method differs from traditional BMF in that the factors are linearly ordered by priority, and factors can contradict each other, meaning that one factor can assign a value of 1 while the other assigns a value of 0. In such a case, the factor with higher priority is the relevant one. Through experiments, we demonstrate that our approach provides a more compact data description than a straightforward application of the traditional BMF methods. Moreover, it is even able to overcome the Schein rank. [ABSTRACT FROM AUTHOR]

Abstract We propose two ways to make factorization of attribute-oriented fuzzy concept lattices recently studied by Ciobanu & Văideanu more efficient. Firstly, we show that the blocks of the corresponding factor lattice are determined by a particular fuzzy interior operator. This allows us to compute an attribute-oriented fuzzy concept lattice by intents. Such a computation requires fewer traversals through data, as the number of the attributes is usually smaller than the number of objects. Secondly, we scale the input data in such a way that the factor lattice can be computed as a one-sided fuzzy-crisp concept lattice. Our experiments indicate that both methods lead to a significant improvement in efficiency of computation of the factor lattice. In addition, we improve and extend the theory provided by Ciobanu & Văideanu. [ABSTRACT FROM AUTHOR]

Dependencies in data describing objects and their attributes represent a key topic in understanding relational data. In this paper, we examine certain dependencies of data described by fuzzy attributes such as green or high performance, i.e. attributes which apply to objects to certain degrees. Such attributes subsume Boolean attributes as a particular case. We utilize the framework of residuated structures of truth degrees as developed in modern fuzzy logic and examine several fundamental problems for our dependencies. These include connections to existing dependencies for fuzzy as well as Boolean attributes, connections to interior- and closure-like structures, definition and properties of semantic entailment including an efficient check of entailment, various model-theoretical properties, a logical calculus of the dependencies inspired by the well-known Armstrong rules with its ordinary-style as well as graded-style syntactico-semantical completeness, fully informative sets of all dependencies that are valid in given data including a constructive description of minimal such sets, as well as various other problems. [ABSTRACT FROM AUTHOR]

We generalize the notion of complete binary relation on complete lattice to residuated lattice valued ordered sets and show its properties. Then we focus on complete fuzzy tolerances on fuzzy complete lattices and prove they are in one-to-one correspondence with extensive isotone Galois connections. Finally, we prove that any fuzzy complete lattice factorized by a complete fuzzy tolerance is again a fuzzy complete lattice. [ABSTRACT FROM AUTHOR]

We provide a new approach to fusion of Fuzzy Formal Concept Analysis and Rough Set Theory. As a starting point we take into account a couple of fuzzy relations, one of them represents the lower approximation, while the other one the upper approximation of a given data table. By defining appropriate concept-forming operators we transfer the roughness of the input data table to the roughness of corresponding formal fuzzy concepts in the sense that a formal fuzzy concept is considered as a collection of objects accompanied with two fuzzy sets of attributes--those which are shared by all the objects and those which at least one object has. In the paper we study the properties of such formal concepts and show their relationship with concepts formed by well-known isotone and antitone operators. [ABSTRACT FROM AUTHOR]

G. Ciobanu, C. Văideanu (2015) [1] define the similarity of objects in attribute-oriented fuzzy concept lattice and claim that it is different from the similarity of objects induced by the corresponding fuzzy context. We show that this claim is wrong and that the two similarities are equal. As a consequence we get that attribute-oriented concept lattices and standard concept lattices induce the same similarity on objects. [ABSTRACT FROM AUTHOR]

We present results on bases of closure systems over residuated lattices, which appear in applications of fuzzy logic. Unlike the Boolean case, the situation is not straightforward as there are two non-commuting generating operations involved. We present a decomposition theorem for a general closure operator and utilize it for computing generators and bases of the closure system. We show that bases are not unique and may in general have different sizes, and obtain a constructive description of the size of a largest base. We prove that if the underlying residuated lattice is a chain, all bases have the same size. [ABSTRACT FROM AUTHOR]

In this paper, we deal with suitable generalizations of the notion of bond between contexts, as part of the research area of Formal Concept Analysis. We study different generalizations of the notion of bond within the-fuzzy setting. Specifically, given a formal context, there are three prototypical pairs of concept-forming operators, and this immediately leads to three possible versions of the notion of bond (so-calledhomogeneous bondwrt certain pair of concept-forming operators). The first results show a close correspondence between a homogeneous bond between two contexts and certain special types of mappings between the sets of extents (or intents) of the corresponding concept lattices. Later, we introduce the so-calledheterogeneous bonds(considering simultaneously two types of concept-forming operators) and generalize the previous relationship to mappings between the sets of extents (or intents) of the corresponding concept lattices. [ABSTRACT FROM AUTHOR]

We present results regarding row and column spaces of matrices whose entries are elements of residuated lattices. In particular, we define the notions of a row and column space for matrices over residuated lattices, provide connections to concept lattices and other structures associated to such matrices, and show several properties of the row and column spaces, including properties that relate the row and column spaces to Schein ranks of matrices over residuated lattices. Among the properties is a characterization of matrices whose row (column) spaces are isomorphic. In addition, we present observations on the relationships between results established in Boolean matrix theory on one hand and formal concept analysis on the other hand. [ABSTRACT FROM AUTHOR]

Organophosphorus compounds (OP) are a constant problem, both in the military and in the civilian field, not only in the form of acute poisoning but also for their long-lasting consequences. No antidote has been found that satisfactorily protects against the toxic effects of organophosphates. Likewise, there is no universal cure to avert damage after poisoning. The key mechanism of organophosphate toxicity is the inhibition of acetylcholinesterase. The overstimulation of nicotinic or muscarinic receptors by accumulated acetylcholine on a synaptic cleft leads to activation of the glutamatergic system and the development of seizures. Further consequences include generation of reactive oxygen species (ROS), neuroinflammation, and the formation of various other neuropathologists. In this review, we present neuroprotection strategies which can slow down the secondary nerve cell damage and alleviate neurological and neuropsychiatric disturbance. In our opinion, there is no unequivocal approach to ensure neuroprotection, however, sooner the neurotoxicity pathway is targeted, the better the results which can be expected. It seems crucial to target the key propagation pathways, i.e., to block cholinergic and, foremostly, glutamatergic cascades. Currently, the privileged approach oriented to stimulating GABAAR by benzodiazepines is of limited efficacy, so that antagonizing the hyperactivity of the glutamatergic system could provide an even more efficacious approach for terminating OP-induced seizures and protecting the brain from permanent damage. Encouraging results have been reported for tezampanel, an antagonist of GluK1 kainate and AMPA receptors, especially in combination with caramiphen, an anticholinergic and anti-glutamatergic agent. On the other hand, targeting ROS by antioxidants cannot or already developed neuroinflammation does not seem to be very productive as other processes are also involved. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is a complex disorder with unknown etiology. Currently, only symptomatic therapy of AD is available, comprising cholinesterase inhibitors and N-methyl-d-aspartate (NMDA) receptor antagonists. Drugs targeting only one pathological condition have generated only limited efficacy. Thus, combining two or more therapeutic interventions into one molecule is believed to provide higher benefit for the treatment of AD. In the presented study, we designed, synthesized, and biologically evaluated 15 novel fluoren-9-amine derivatives. The in silico prediction suggested both the oral availability and permeation through the blood–brain barrier (BBB). An initial assessment of the biological profile included determination of the cholinesterase inhibition and NMDA receptor antagonism at the GluN1/GluN2A and GluN1/GluN2B subunits, along with a low cytotoxicity profile in the CHO-K1 cell line. Interestingly, compounds revealed a selective butyrylcholinesterase (BChE) inhibition pattern with antagonistic activity on the NMDARs. Their interaction with butyrylcholinesterase was elucidated by studying enzyme kinetics for compound 3c in tandem with the in silico docking simulation. The docking study showed the interaction of the tricyclic core of new derivatives with Trp82 within the anionic site of the enzyme in a similar way as the template drug tacrine. From the kinetic analysis, it is apparent that 3c is a competitive inhibitor of BChE. [ABSTRACT FROM AUTHOR]

"Novichok" refers to a new group of nerve agents called the A-series agents. Their existence came to light in 2018 after incidents in the UK and again in 2020 in Russia. They are unique organophosphorus-based compounds developed during the Cold War in a program called Foliant in the USSR. This review is based on original chemical entities from Mirzayanov's memoirs published in 2008. Due to classified research, a considerable debate arose about their structures, and hence, various structural moieties were speculated. For this reason, the scientific literature is highly incomplete and, in some cases, contradictory. This review critically assesses the information published to date on this class of compounds. The scope of this work is to summarize all the available and relevant information, including the physicochemical properties, chemical synthesis, mechanism of action, toxicity, pharmacokinetics, and medical countermeasures used to date. The environmental stability of A-series agents, the lack of environmentally safe decontamination, their high toxicity, and the scarcity of information on post-contamination treatment pose a challenge for managing possible incidents. [ABSTRACT FROM AUTHOR]

We study the problem of decomposition of object-attribute matrices whose entries contain degrees to which objects have attributes. The degrees are taken from a bounded partially ordered scale. Examples of such matrices are binary matrices, matrices with entries from a finite chain, or matrices with entries from the unit interval [0, 1]. We study the problem of decomposition of a given object-attribute matrix I with degrees into an object-factor matrix A with degrees and a binary factor-attribute matrix B, with the number of factors as small as possible. We present a theorem which shows that decompositions which use particular formal concepts of I as factors for the decomposition are optimal in that the number of factors involved is the smallest possible. We show that the problem of computing an optimal decomposition is NP-hard and present two heuristic algorithms for its solution along with their experimental evaluation. For the first algorithm, we provide its approximation ratio. Experiments indicate that the second algorithm, which is considerably faster than the first one, delivers decompositions whose quality is comparable to the decompositions delivered by the first algorithm. We also present an illustrative example demonstrating a factor analysis interpretation of the decomposition studied in this paper. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a novel light transmission technique for detecting sol–gel transition. The technique uses a fluorescent light source, a CCD camera and a clear borosilicate mold to measure the light transmission characteristics of liquid aerogel precursors as they gel. We used tetramethoxysilane-based aerogel precursors (TMOS:MeOH:H2O:NH4OH). Some of the precursor mixtures were doped with strongly absorbing probes in order to facilitate visual observation of the gelation process and improve image quality, whereas others were not doped. Solutions were placed in the mold and heated under pressure in a hot-press. In all cases, we observed that the solutions darkened in appearance and recorded this phenomenon with the CCD camera. To quantify the degree of darkening we converted the RGB images to a hue-saturation-intensity color space. Plots of hue and intensity versus temperature were characterized by a decrease at 95–115°C. Visual inspection confirmed that the solutions started to gel in this temperature range, resulting in an increase in particle size, increase in extent of light scattering, and subsequent decrease in transmitted light. [Copyright &y& Elsevier]

• Small set of seven compounds was developed building upon YNT-185. • Compounds were tested as orexin receptor type 2 modulators. • Switch from agonist (YNT-185) to antagonist (new compounds) was observed. • Compounds retained low cytotoxicity profile and predicted CNS availability. • Top-ranked compound 15 was submitted to pharmacokinetic study in vivo. YNT-185 is the first known small molecule acting as orexin 2 receptor (OX 2 R) agonist with implication to narcolepsy treatment, served as a template scaffold in generating a small set of seven compounds with predictive affinity to OX 2 R. The design of the new small molecules was driven mostly by improving physicochemical properties of the parent drug YNT-185 in parallel with in silico studies, later suggesting their favorable binding modes within the active site of OX 2 R. We obtained seven new potential OX 2 R binders that were evaluated in vitro for their CNS availability, cytotoxicity, and behavior pattern on OX 2 R. Out of them, 15 emerged as the most potent modulator of OX 2 R, which, contrary to YNT-185, displayed inverse mode of action, i.e. antagonist profile. 15 was also submitted to an in vivo experiment revealing its ability to permeate through BBB into the brain with a short half-life. [ABSTRACT FROM AUTHOR]

The neuropeptides, orexin A and orexin B (also known as hypocretins), are produced in hypothalamic neurons and belong to ligands for orphan G protein-coupled receptors. Generally, the primary role of orexins is to act as excitatory neurotransmitters and regulate the sleep process. Lack of orexins may lead to sleep disorder narcolepsy in mice, dogs, and humans. Narcolepsy is a neurological disorder of alertness characterized by a decrease of ability to manage sleep-wake cycles, excessive daytime sleepiness, and other symptoms, such as cataplexy, vivid hallucinations, and paralysis. Thus, the discovery of orexin receptors, modulators, and their causal implication in narcolepsy is the most important advance in sleep-research. The presented work is focused on the evaluation of compounds L1–L11 selected by structure-based virtual screening for their ability to modulate orexin receptor type 2 (OX2R) in comparison with standard agonist orexin-A together with their blood-brain barrier permeability and cytotoxicity. We can conclude that the studied compounds possess an affinity towards the OX2R. However, the compounds do not have intrinsic activity and act as the antagonists of this receptor. It was shown that L4 was the most potent antagonistic ligand to orexin A and displayed an IC50 of 2.2 µM, offering some promise mainly for the treatment of insomnia. [ABSTRACT FROM AUTHOR]