MEC-Based Jamming-Aided Anti-Eavesdropping with Deep Reinforcement Learning for WBANs

Wireless body area network (WBAN) suffers secure challenges, especially the eavesdropping attack, due to constraint resources. In this article, deep reinforcement learning (DRL) and mobile edge computing (MEC) technology are adopted to formulate a DRL-MEC-based jamming-aided anti-eavesdropping (DMEC-JAE) scheme to resist the eavesdropping attack without considering the channel state information. In this scheme, a MEC sensor is chosen to send artificial jamming signals to improve the secrecy rate of the system. Power control technique is utilized to optimize the transmission power of both the source sensor and the MEC sensor to save energy. The remaining energy of the MEC sensor is concerned to ensure routine data transmission and jamming signal transmission. Additionally, the DMEC-JAE scheme integrates with transfer learning for a higher learning rate. The performance bounds of the scheme concerning the secrecy rate, energy consumption, and the utility are evaluated. Simulation results show that the DMEC-JAE scheme can approach the performance bounds with high learning speed, which outperforms the benchmark schemes.

Joint application of radar visibility reduction and anti-radar masking technologies to protect aircraft from remote monitoring systems

Using spectral energy equations of transmission-reception of wave processes in radio channel with scattering on object and direct radio channel, analysis of energy ratios of information signals and active masking interference at inputs of receivers of remote monitoring systems is carried out. Measures to reduce visibility are aimed at changing the reflective signatures of objects in the interests of reducing the de-masking features contained in secondary electromagnetic radiation to limits that exclude the performance of radar monitoring tasks at established distances and time intervals. Active interference is designed to mask information signals in receiving channels of radar at power that does not allow detecting their designers by passive radar. In case of joint application of not iceability reducing devices and active jammers, radar range reducing coefficient is determined by product of coefficient characterizing possibility of autonomous masking of information signals and coefficient achievable due to reduction of secondary electromagnetic radiation power in the second degree. The laws of increase of aircraft stealth from radar observation with joint application of technologies of reduction of radar visibility and masking by intentional interference created from sides of protected objects and from assigned points have been investigated. In order to maintain the desired signal-to-noise ratio at the output of the receiver with a decrease in the duration of the probing signal, it is necessary to proportionally increase the density of the emitted energy. With given antenna sizes, the maximum signal transmission range is proportional to the root square of their cyclic carrier frequency; increase of this parameter leads to increase of partial coefficient of directional action and effective area of antenna. With a decrease in the cyclic frequency of the carrier of the probing signal, inorder to maintain the required directional properties of the antennas, it is necessary to increase their dimensions.

Equilibrium Stochastic Delay Processes

Stochastic processes with temporal delay play an important role in science and engineering whenever finite speeds of signal transmission and processing occur. However, an exact mathematical analysis of their dynamics and thermodynamics is available for linear models only. We introduce a class of stochastic delay processes with nonlinear time-local forces and linear time-delayed forces that obey fluctuation theorems and converge to a Boltzmann equilibrium at long times. From the point of view of control theory, such ``equilibrium stochastic delay processes'' are stable and energetically passive, by construction. Computationally, they provide diverse exact constraints on general nonlinear stochastic delay problems and can, in various situations, serve as a starting point for their perturbative analysis. Physically, they admit an interpretation in terms of an underdamped Brownian particle that is either subjected to a time-local force in a non-Markovian thermal bath or to a delayed feedback force in a Markovian thermal bath. We illustrate these properties numerically for a setup familiar from feedback cooling and point out experimental implications.

The Mechanisms of GPR55 Receptor Functonal Selectivity

The objective of the project is to establish the mechanisms of multidirectional signal transmission through the same G-protein coupled receptor GPR55. Using the CRISPR-Cas9 system, clones of the MDA-MB-231 line knockout for the GPR55 (3 clones) and CB2 (CNR2 - 6 clones) receptor genes were obtained. On clones of the MDA-MB-231 line with a knockout CB2 receptor, the cytotoxic activity of the pro-apoptotic ligand docosahexaenoyldopamine (DHA-DA) did not change or slightly increased, while the pro-proliferative activity of the most active synthetic ligand of the GPR55 receptor (ML-184) completely disappeared. On the original line MDA-MB-231, the stimulatory effect of ML-184 is removed by the CB2 receptor blocker, but not by GPR55. At the same time, the stimulating effect of ML-184 is practically not manifested on cell lines knockout at the GPR55 receptor. Thus, it can be confidently assumed that when proliferation is stimulated with the participation of the GPR55 receptor, a signal is transmitted from the CB2 receptor to the GPR55 receptor due to the formation of a heterodimer. GPR18 and TRPV1 receptors are additionally involved in the implementation of the cytotoxic effect of DHA-DA, while the CB1 receptor is not involved. In the implementation of the cytotoxic action of DHA-DA, the predominant participation of one of the Ga subunits was not found, but the Ga13 subunit plays a decisive role in the implementation of the proproliferative action. The Gaq subunit is also important, although to a lesser extent than Ga13.

Selective control of synaptically-connected circuit elements by all-optical synapses

Understanding percepts, engrams and actions requires methods for selectively modulating synaptic communication between specific subsets of interconnected cells. Here, we develop an approach to control synaptically connected elements using bioluminescent light: Luciferase-generated light, originating from a presynaptic axon terminal, modulates an opsin in its postsynaptic target. Vesicular-localized luciferase is released into the synaptic cleft in response to presynaptic activity, creating a real-time Optical Synapse. Light production is under experimenter-control by introduction of the small molecule luciferin. Signal transmission across this optical synapse is temporally defined by the presence of both the luciferin and presynaptic activity. We validate synaptic Interluminescence by multi-electrode recording in cultured neurons and in mice in vivo. Interluminescence represents a powerful approach to achieve synapse-specific and activity-dependent circuit control in vivo.

Influence of Nicotine from Diverse Delivery Tools on the Autonomic Nervous and Hormonal Systems

Background: Through measurements of the heart rate variability (HRV) accompanied by the pertinent biomarker assays, the effects of nicotine and byproducts derived from alternative nicotine delivery systems (ANDS) on the autonomic nervous system (ANS) and hormonal system have been investigated. Methods: HRV was studied in a group of volunteers (17 people), involving non-smokers, i.e., who never smoked before (11), ex-smokers (4) and active smokers (2). ANDS and smoking simulators, including regular, nicotine-free and electronic cigarettes; tobacco heating systems; chewing gums and nicotine packs of oral fixation (nic-packs), were used. Blood pressure, levels of stress hormones in saliva and catecholamines in the blood were also monitored. Results: HRV analysis showed relatively small changes in HRV and in the other studied parameters with the systemic use of nic-packs with low and moderate nicotine contents (up to 6 mg) compared to other ANDS. Conclusions: The HRV method is proven to be a promising technique for evaluation of the risks associated with smoking, dual use of various ANDS and studying the biomedical aspects of smoking cessation. Nic-packs are shown to be leaders in biological safety among the studied ANDS. A sharp surge in the activity of the sympathetic division of the ANS within the first minutes of the use of nicotine packs implies that nicotine begins to act already at very low doses (before entering the blood physically in any significant amount) through fast signal transmission to the brain from the nicotinic and taste buds located in the mouth area.

Anti-infection roles of miR-155-5p packaged in exosomes secreted by dendritic cells infected with Toxoplasma gondii

Background Toxoplasma gondii is a zoonotic intracellular protozoon that is estimated to infect about 30% of the world’s population, resulting in toxoplasmosis in immunocompromised patients and adverse outcomes in cases of primary infection during pregnancy. Exosomes are tubular vesicles secreted by cells, and function in intercellular communication. It has been reported that the exosomes secreted by T. gondii-infected immune cells transmit infection signals to the uninfected cells. However, the mechanism and effect of the exosome transmission are still vague. We therefore investigated the function of the exosomes transmitted from DC2.4 cells infected with the T. gondii RH strain (Tg-DC-Exo) to the uninfected cells, as well as their roles in anti-infection. Methods We conducted exosome isolation and identification with ultracentrifugation, transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and western blot (WB) analysis. Exosome uptake by recipient cells was identified by PKH67 assay. The signal transmission and the abundance of miR-155-5p were determined using transwell assay and qRT-PCR. For detection of immune responses, cytokine secretion was evaluated. The T. gondii B1 gene was determined to evaluate tachyzoite proliferation. Results We observed that Toxoplasma infection upregulated miR-155-5p expression in DC2.4 cell-secreted exosomes, and those exosomes could be ingested by murine macrophage RAW264.7 cells. Tg-DC-Exo and miR-155-5p stimulated host proinflammatory immune responses including increased production of proinflammatory cytokines IL-6 and TNF-α, and proinflammatory marker-inducible nitric oxide synthase (iNOS). The NF-κB pathway was activated by downregulation of SOCS1, leading to inhibition of T. gondii tachyzoite proliferation in RAW264.7 cells. Conclusions Our findings provide a novel mechanism for how infected cells transmit infection signals to the uninfected cells through exosome secretion after T. gondii infection, followed by inflammatory responses and anti-infection reactions, which may help us develop a new strategy for toxoplasmosis prevention, especially in immunocompromised patients. Graphical Abstract

Salivary Exosomes: From Waste to Promising Periodontitis Treatment

Periodontitis is a chronic inflammatory condition that causes tooth loss by destroying the supporting components of the teeth. In most cases, it is difficult to diagnose early and results in severe phases of the disease. Given their endogenous origins, exosomes, which are rich in peptides, lipids, and nucleic acids, have emerged as a cell-free therapeutic approach with low immunogenicity and increased safety. Because the constituents of exosomes can be reprogrammed depending on disease states, exosomes are increasingly being evaluated to act as potential diagnostic biomarkers for dental disease, including periodontitis. Exosomes also have been demonstrated to be involved in inflammatory signal transmission and periodontitis progression in vitro, indicating that they could be used as therapeutic targets for periodontal regeneration. Nevertheless, a review on the involvement of salivary exosomes in periodontitis in impacting the successful diagnosis and treatment of periodontitis is still lacking in the literature. Thus, this review is intended to scrutinize recent advancements of salivary exosomes in periodontitis treatment. We summarize recent research reports on the emerging roles and characteristics of salivary exosomes, emphasizing the different expressions and changed biological roles of exosomes in periodontitis.

Social isolation induces neuroinflammation and microglia overactivation, while dihydromyricetin prevents and improves them

Background Anxiety disorders are the most prevalent mental illnesses in the U.S. and are estimated to consume one-third of the country’s mental health treatment cost. Although anxiolytic therapies are available, many patients still exhibit treatment resistance, relapse, or substantial side effects. Further, due to the COVID-19 pandemic and stay-at-home order, social isolation, fear of the pandemic, and unprecedented times, the incidence of anxiety has dramatically increased. Previously, we have demonstrated dihydromyricetin (DHM), the major bioactive flavonoid extracted from Ampelopsis grossedentata, exhibits anxiolytic properties in a mouse model of social isolation-induced anxiety. Because GABAergic transmission modulates the immune system in addition to the inhibitory signal transmission, we investigated the effects of short-term social isolation on the neuroimmune system. Methods Eight-week-old male C57BL/6 mice were housed under absolute social isolation for 4 weeks. The anxiety-like behaviors after DHM treatment were examined using elevated plus-maze and open field behavioral tests. Gephyrin protein expression, microglial profile changes, NF-κB pathway activation, cytokine level, and serum corticosterone were measured. Results Socially isolated mice showed increased anxiety levels, reduced exploratory behaviors, and reduced gephyrin levels. Also, a dynamic alteration in hippocampal microglia were detected illustrated as a decline in microglia number and overactivation as determined by significant morphological changes including decreases in lacunarity, perimeter, and cell size and increase in cell density. Moreover, social isolation induced an increase in serum corticosterone level and activation in NF-κB pathway. Notably, DHM treatment counteracted these changes. Conclusion The results suggest that social isolation contributes to neuroinflammation, while DHM has the ability to improve neuroinflammation induced by anxiety.