Resonant probing spin-0 and spin-2 dark matter mediators with fixed target experiments

We discuss the mechanism to produce electron-specific dark matter mediators of spin-0 and spin-2 in the electron fixed target experiments such as NA64 and LDMX. The secondary positrons induced by the electromagnetic shower can produce the mediators via annihilation on atomic electrons. That mechanism, for some selected kinematics, results in the enhanced sensitivity with respect to the bounds derived by the bremsstrahlunglike emission of the mediator in the specific parameter space. We derive the corresponding experimental reach of the NA64 and LDMX.Comment: 12 pages, 7 figures. Typos are corrected, efficiencies are added, the version is accepted for publication in PR

Electrical properties of polyurethane metal complexes

The static and dynamic electrical conductivity of coordination compounds of 2, 4-tolylene diisocyanate with Cu (II) and Fe (II) halides, and also polyurethanes synthesized from them are studied. According to the proposed model, the electrical conductivity of metal coordination polyurethanes is associated with electron exchange bettween metal ions of different valence, and depends on saturation with electrons of hetero-atoms entering into the composition of the flexible parts of the macro-chain. © 1990

Artificial intelligence as a legal category: doctrinal approach to formulating a definition

Objective: to conduct a critical analysis of the existing definitions of artificial intelligence and develop an authors’ version of the concept acceptable for legal sciences.Methods: the methodological basis of the study is a set of scientific cognition methods, including abstract-logical method, comparison and correlation analysis.Results: the main regularities of decision-making by artificial intelligence are identified; the mechanism of its perception of objective reality is determined; the fundamental ability of machine learning to conform its behavior to socially acceptable processes is confirmed. It is assumed that there are many ways to describe artificial intelligence: by indicating the action mechanism, the basic operation principles, the range of tasks to be solved, etc. However, the most convincing and consistent is position of those researchers who tend to describe the AI phenomenon by designating its properties and characteristics. The authors state that there is no definition of “artificial intelligence” in the modern legal doctrine. As a result of a comprehensive analysis of various scientific sources in a systematic unity with own judgments, it is proposed to introduce the author’s version of the “artificial intelligence” concept into scientific circulation.Scientific novelty: the paper presents an assessment of the “artificial intelligence” concept definitions available in the scientific literature and legal framework, as well as the authors’ opinion on their relevance, comprehensiveness and topicality; there is an attempt to formulate the definition taking into account all the significant properties of artificial intelligence.Practical significance: is due to the current impossibility to apply legal norms and rules to relations involving artificial intelligence taking into account their specifics. The main provisions and conclusions of the study can be used to improve the mechanisms of legal regulation of artificial intelligence in the Russian Federation

Mistletoe lectin dissociates into catalytic and binding subunits before translocation across the membrane to the cytoplasm

AbstractHybridomas producing monoclonal antibodies (mAbs) against the mistletoe lectin A-chain (MLA) were obtained to investigate the intracellular routing and translocation of ribosome-inactivating proteins. Anti-MLA mAb MNA5 did not bind the holotoxin but interacted with isolated MLA. This epitope was not recognized upon MLA denaturation or conjugation of MLA with the ricin binding subunit (RTB). Furthermore, the mAbs did not appreciably react with a panel of MLA synthetic octapeptides linked to the surface of polyethylene pins. A study of the cytotoxicity of mistletoe lectin, ricin, and chimeric toxin MLA/RTB for the hybridomas revealed that interchain disulfide bond reduction and subunit dissociation are required for cytotoxic activity of mistletoe lectin

Formation of 24Mg* in the Splitting of 28Si Nuclei by 1-GeV Protons

The 28Si(p, p' gamma)24Mg reaction has been studied at the ITEP accelerator by the hadron-gamma coincidence method for a proton energy of 1 GeV. Two reaction products are detected: a 1368.6-keV gamma-ray photon accompanying the transition of the 24Mg* nucleus from the first excited state to the ground state and a proton p' whose momentum is measured in a magnetic spectrometer. The measured distribution in the energy lost by the proton in interaction is attributed to five processes: the direct knockout of a nuclear alpha cluster, the knockout of four nucleons with a total charge number of 2, the formation of the DeltaSi isobaric nucleus, the formation of the Delta isobar in the interaction of the incident proton with a nuclear nucleon, and the production of a pi meson, which is at rest in the nuclear reference frame. The last process likely corresponds to the reaction of the formation of a deeply bound pion state in the 28P nucleus. Such states were previously observed only on heavy nuclei. The cross sections for the listed processes have been estimated.Comment: 14 pages, 3 figures submitted to JETP Letter