Signal Relay Research Articles

Amplifying In-Vehicle DTV Entertainment: ATSC 3.0 Broadcast Signal Relay via WiFi Gateway

Amplifying In-Vehicle DTV Entertainment: ATSC 3.0 Broadcast Signal Relay via WiFi Gateway

A CMOS-Based 4-Bit Absolute-Value Detector for BCI Signal Feature Extraction

In recent years, the integrated circuit industry has developed rapidly. Since the advent of the first computer, the performance of chips has increased exponentially while the size and power consumption have also decreased. Today, a high-performance chip is much smaller than a card. The increase in computing power also means that there are more possibilities in the field of computing and simulation. Many disciplines have also made new breakthroughs due to the improvement of computing power. Brain-computer interfaces and technologies such as rehabilitation medicine and virtual reality based on it are very promising technologies that allow the brain to interact directly with external devices. However, the signals of the human brain are very complex, and the brain-computer interface, as a signal relay station between the human brain and external devices, requires very powerful data processing capabilities. This article will first introduce the brain-computer interface technology and the method of processing the signals in it, and then propose an efficient absolute-value detector circuit design to achieve a very important step in signal processing.

Mechanical stimulation from the surrounding tissue activates mitochondrial energy metabolism in Drosophila differentiating germ cells.

In multicellular lives, the differentiation of stem cells and progenitor cells is often accompanied by a transition from glycolysis to mitochondrial oxidative phosphorylation (OXPHOS). However, the underlying mechanism of this metabolic transition remains largely unknown. In this study, we investigate the role of mechanical stress in activating OXPHOS during differentiation of the female germline cyst in Drosophila. We demonstrate that the surrounding somatic cells flatten the 16-cell differentiating cyst, resulting in an increase of the membrane tension of germ cells inside the cyst. This mechanical stress is necessary to maintain cytosolic Ca2+ concentration in germ cells through a mechanically activated channel, transmembrane channel-like. The sustained cytosolic Ca2+ triggers a CaMKI-Fray-JNK signaling relay, leading to the transcriptional activation of OXPHOS in differentiating cysts. Our findings demonstrate a molecular link between cell mechanics and mitochondrial energy metabolism, with implications for other developmentally orchestrated metabolic transitions in mammals.

Revealing observatory networks through object stories: Instrumental networks

This paper presents three pieces that use objects, or object types, to reveal the material, personal, institutional and commercial networks that surrounded the introduction and successful use of instruments, systems and techniques. The objects explored are: the Hourly Signal Relay, used within the time signal system of the Royal Observatory, Greenwich, from the mid-nineteenth century; photographic glass plates from the British 1874 transit of Venus expeditions; and an electronic imaging tube, Lallemand’s camera, developed in Paris and used at the Lick Observatory in California in the 1960s. Each story uses examples of failure as a means of highlighting a lack of robustness in or effort required to maintain these networks. Once created, however, such networks could, as the second two stories note, go on to develop and support alternative approaches, helping to create success from apparent failure. Nevertheless, complexity, failure and fragility have also led to the underrepresentation or obscurity of these objects in museum collections, until given focused attention in these studies. The paper forms part of a collection of articles: Revealing observatory networks through object stories. The other papers in the collection are ‘Object itineraries’, and ‘Observatory audiences’ and the genesis of the collection is discussed in the ‘Introduction’.

Fluid shear stress triggers cholesterol biosynthesis and uptake in inner medullary collecting duct cells, independently of nephrocystin-1 and nephrocystin-4.

Renal epithelial cells are subjected to fluid shear stress of urine flow. Several cellular structures act as mechanosensors-the primary cilium, microvilli and cell adhesion complexes-that directly relay signals to the cytoskeleton to regulate various processes including cell differentiation and renal cell functions. Nephronophthisis (NPH) is an autosomal recessive tubulointerstitial nephropathy leading to end-stage kidney failure before adulthood. NPHP1 and NPHP4 are the major genes which code for proteins that form a complex at the transition zone of the primary cilium, a crucial region required for the maintenance of the ciliary composition integrity. These two proteins also interact with signaling components and proteins associated with the actin cytoskeleton at cell junctions. Due to their specific subcellular localization, we wondered whether NPHP1 and NPHP4 could ensure mechanosensory functions. Using a microfluidic set up, we showed that murine inner medullary collecting ductal cells invalidated for Nphp1 or Nphp4 are more responsive to immediate shear exposure with a fast calcium influx, and upon a prolonged shear condition, an inability to properly regulate cilium length and actin cytoskeleton remodeling. Following a transcriptomic study highlighting shear stress-induced gene expression changes, we showed that prolonged shear triggers both cholesterol biosynthesis pathway and uptake, processes that do not seem to involve neither NPHP1 nor NPHP4. To conclude, our study allowed us to determine a moderate role of NPHP1 and NPHP4 in flow sensation, and to highlight a new signaling pathway induced by shear stress, the cholesterol biosynthesis and uptake pathways, which would allow cells to cope with mechanical stress by strengthening their plasma membrane through the supply of cholesterol.

Neuroprotective effect of chitosan oligosaccharide on alcohol-induced hippocampal injury using proteomic analysis.

Alcoholism is a serious public health problem, and the abuse of drinking seriously damages the health of people. Chitosan oligosaccharides (COSs) are small-molecule oligosaccharides with amino groups that have many unique properties. The neuroprotective effect of COS on alcohol-induced hippocampal injury in Sprague-Dawley (SD) rats was investigated. The discrimination ratio of the COS group in the Y-maze experiment was 59.3% higher than that of the ETOH group. Meanwhile, the discrimination index was less than 0 in the ETOH group but greater than 0 in the COS group during the object recognition test. The cells in the COS group were more tightly arranged than those in the ETOH group. Proteomics was used to identify differentially expressed proteins in the hippocampus. There were 27 differentially expressed proteins in the COS and ETOH group for further bioinformatic analysis. There are three enriched pathway categories, namely, primary immunodeficiency, hedgehog signaling, and sulfur relay system. Next, sonic hedgehog signaling pathway-related proteins were verified through western blotting. The protein expression level of β-arrestin-2 in the COS group was 2.85 times higher than that in the ETOH group. This work may contribute to understanding the underlying mechanism of the neuroprotective effect of COS against alcohol-induced hippocampal injury in SD rats.

Processing of retransmitted GPS signals in the problem of measuring the total electron content in the ionosphere

Objectives. For a method for estimating the total electron content in the ionosphere based on the retransmission of the L1 GPS navigation signal by a repeater nanosatellite (SR) to the frequencies of 150/400 MHz allocated for geophysical research and their reception at a ground-based receiving point (RP), it is necessary to develop the algorithms for coherent accumulation of received relayed signals and measurement of the difference between their delays at observation intervals up to a few seconds.Methods. The proposed algorithms provide phase demodulation of the received signals at each of the relay frequencies in accordance with the dynamics of the mutual spatial movement of the navigation satellite (NS), SR and RP; multiplying the result by the estimate of the navigation message combined time delay, generated by the receiver of the direct navigation signal on the NS-RP route, intra-period processing over the entire duration of the observation in a filter matched with the signal of the navigation satellite, and inter-period coherent accumulation of the results of intra-period processing at a single-valued range interval. Coherent accumulation, taking into account a random uncontrolled shift in the frequency of the retransmitted signal, is implemented by discrete Fourier transform of the vectors formed for each resolution element in the delay time from inter-period readings of the results of intra-period processing, taking into account the range migration during the mutual movement of the NS, SR and RP.Results. It is shown that by the output signal of the coherent accumulator makes it is possible to detect retransmitted signals at each of the retransmission frequencies, to measure accurately the difference in delay times, and estimate the total electron content on the SR-RP path. The results of modeling are presented, confirming the efficiency of the proposed algorithms in estimating the total electron content on the SR-RP route.Conclusion. An algorithm for coherent accumulation of received retransmitted signals and measurement of the difference between their delays is developed, and its simulation is performed. The algorithm can be used for estimating TEC based on the retransmission of signals from GPS.

SWIPT Aided Cooperative Communications With Energy Harvesting-Based Selective-Decode-and-Forward Protocol: Benefiting From Channel Aging Effect

Simultaneous wireless information and power transfer (SWIPT) in radio-frequency (RF) bands enables flexible deployment of battery-powered relays for extending communication coverage. Relays receive downlink RF signals emitted by a source for information decoding and energy harvesting, while the harvested energy is consumed for both information decoding and information forwarding to a destination. An energy harvesting based selective-decode-and-forward (EH-SDF) protocol is proposed, where only the relays having information correctly decoded are activated for information forwarding, while others harvest and store energy for the future use. By considering the channel aging effect, we propose a joint relay selection, power allocation, transmit beamforming and signal splitting design in order to maximise the end-to-end (e2e) throughput of this EH-SDF aided cooperative communication system. Two scenarios with/without direct link between the source and the destination are studied, respectively. The original formulated non-convex optimisation problems with coupled variables are decoupled into three subproblems which are solved by an iterative optimisation algorithm. Numerical results demonstrate that our design with the EH-SDF protocol achieves a higher e2e throughput than the traditional decode-and-forward (DF) counterpart. Moreover, the impact of the channel aging effect on the e2e throughput is also evaluated.

Mechanical Characteristics and Vibration Control of Railway Signal Relay

Introduction: In order to solve the problems of time-consuming and poor effects of traditional mechanical vibration control methods for the relay, the mechanical characteristics and vibration control of railway signal relays are studied in this paper. Based on the analysis of the mechanical characteristics of railway signal relays, the mechanical characteristic parameters of the relay, such as contact force, initial pressure, contact clearance, and overtravel are explored. On this basis, mechanical vibration control is completed based on particle swarm optimization. Methods: First, sensors are used to collect the data on the railway signal relay, and the mechanical vibration control model of the railway signal relay is built. Then, the structure of the PID vibration controller and LQR vibration controller in the model is analyzed. Finally, the controller parameters are adjusted through particle swarm optimization to improve the mechanical vibration control effect of the relay. Results: The simulation results show that the average signal-to-noise ratio of the method is 67dB, the collected data has low noise, and the control time is short, which is 1.4 s. Conclusion: The displacement of the railway signal relay controlled by the method is always less than 0.15 mm, and the control effect is good, which can be widely used in practice.

Anti-PD-L1 antibodies promote cellular proliferation by activating the PD-L1-AXL signal relay in liver cancer cells.

Immune checkpoint inhibitors (ICIs) are emerging treatments for advanced hepatocellular carcinoma (HCC); however, evidence has shown they may induce hyperprogressive disease via unexplained mechanisms. In this study, we investigated the possible stimulative effect of ICIs on programmed cell death-ligand 1 (PD-L1)-harboring liver cancer cells under immunocompetent cell-free conditions. The sarcomatous HAK-5 cell line displayed the highest expression of PD-L1 among 11 human liver cancer cell lines used in this study. HLF showed moderate expression, while HepG2, Hep3B, and HuH-7 did not show any. Moreover, sarcomatous HCC tissues expressed high levels of PD-L1. We observed approximately 20% increase in cell proliferation in HAK-5 cells treated with anti-PD-L1 antibodies, such as durvalumab and atezolizumab, for 48h compared with that of those treated with the control IgG and the anti-PD-1 antibody pembrolizumab. No response to durvalumab or atezolizumab was shown in PD-L1-nonexpressing cells. Loss-of-function and gain-of-function experiments for PD-L1 in HAK-5 and HepG2 cells resulted in a significant decrease and increase in cell proliferation, respectively. Phosphorylated receptor tyrosine kinase array and immunoprecipitation revealed direct interactions between PD-L1 and AXL in tumor cells. This was stabilized by extrinsic anti-PD-L1 antibodies in a glycosylated PD-L1-dependent manner. Activation of AXL, triggering signal relay to the Akt and Erk pathways, boosted tumor cell proliferation both in vitro and in xenografted tumors in NOD/SCID mice. Collectively, this suggests that anti-PD-L1 antibodies stimulate cell proliferation via stabilization of the PD-L1-AXL complex in specific types of liver cancer, including in HCC with mesenchymal components. Therapeutic anti-PD-L1 antibodies promote cell proliferation by stabilizing the PD-L1-AXL complex in PD-L1-abundant neoplasms, including in HCC with mesenchymal components. Such a mechanism may contribute to the development of hyperprogressive disease.

Encoding–decoding-based fusion estimation with filter-and-forward relays and stochastic measurement delays

This paper addresses the encoding–decoding-based fusion estimation problem for a class of systems with signal relays and stochastic measurement delays. A set of Bernoulli distributed random variables is used to model the randomly occurring measurement delays. To enhance the system performance and extend the transmission distance, a filter-and-forward relay is adopted in the transmission link. To handle the limited bandwidth of the communication channels, an encoding–decoding scheme based on a probabilistic quantizer is proposed for the sensor–relay and relay–estimator channels. For each relay, a local filter is constructed with a proper filter gain at each time step with aim to minimize an upper bound of the local estimation error covariance. The effects of the encoding–decoding scheme on the error covariance are also analyzed quantitatively. The estimates obtained from the local filters are then fused at the remote estimator using the covariance intersection fusion strategy. Finally, a target tracking simulation example is presented to demonstrate the effectiveness of the proposed framework.

Vibration signal-based defect detection method for railway signal relay using parameter-optimized VMD and ensemble feature selection

Railway signal relay (RSR) plays a critical role in the railway signaling system and its failure may bring serious consequences. At present, the manual-based RSR defect detection method has many shortcomings. A vibration-based defect detection method for RSR is proposed to solve this problem. First, since most of the variational mode decomposition (VMD) optimization strategies do not apply to the vibration signal of RSR, a parameter-optimized VMD based on a hybrid criterion of sample entropy (SampEn) and Pearson correlation coefficient (PCC) is proposed. Second, an ensemble feature selection method combining Filter method and Embedded method is proposed to select defect-sensitive features. The ensemble is considered as a multi-criteria decision-making (MCDM) problem and solved using the VIKOR method, which can integrate the advantages of each feature selection method to select the optimal feature subset. Finally, the effectiveness of the proposed method is verified by real vibration signals of RSR.

Mechanical pressure-induced dedifferentiation of myofibroblasts inhibits scarring via SMYD3/ITGBL1 signaling.

Pressure therapy (PT) is an effective intervention for reducing scarring, but its underlying mechanism remains largely unclear. Here, we demonstrate that human scar-derived myofibroblasts dedifferentiate into normal fibroblasts in response to PT, and we identify how SMYD3/ITGBL1 contributes to the nuclear relay of mechanical signals. In clinical specimens, reductions in SMYD3 and ITGBL1 expression levels are strongly associated with the anti-scarring effects of PT. The integrin β1/ILK pathway is inhibited in scar-derived myofibroblasts upon PT, leading to decreased TCF-4 and subsequently to reductions in SMYD3 expression, which reduces the levels of H3K4 trimethylation (H3K4me3) and further suppresses ITGBL1 expression, resulting the dedifferentiation of myofibroblasts into fibroblasts. In animal models, blocking SMYD3 expression results in reductions of scarring, mimicking the positive effects of PT. Our results show that SMYD3 and ITGBL1 act as sensors and mediators of mechanical pressure to inhibit the progression of fibrogenesis and provide therapeutic targets for fibrotic diseases.

Video between Architecture and Telepathy

On 6 January 1973, Chilean media artist Juan Downey exhibited Plato Now at the Everson Museum of Art in Syracuse, New York. A hybrid multichannel video installation and performance, this was Downey’s restaging of Plato’s Parable of the Cave—the “Now” registering what the myth might look like from the vantage of his own historical moment. And whereas Plato’s original operated through an inflexible division between the space of the mind and a derivative sensual reality, Plato Now explicitly sought to blur those philosophical lines by assembling a relay of invisible energies, brain waves, video signals, and telepathic communications, such that the space of mind and sensual reality became speculatively entangled. This article clarifies just how Plato Now did this, and situates its philosophical vision as a significant, if relatively unremarked, aesthetic prefiguration of the new materialist tendencies towards relationality, hybrid assemblages, and vibrant conceptions of energy and matter.

Joint Optimization of Condition-Based Maintenance and Performance Control for Linear Multi-State Consecutively Connected Systems

Industrial systems such as signal relay stations and oil pipeline systems can be modeled as linear multi-state consecutively connected systems, which comprise sequentially ordered elements and fail if the first and the final elements are not connected. The performance level of each element is controllable, which determines how many elements an element can connect and affects its degradation rate. Accumulated degradation can cause element failure, which may lead to costly system failure. This paper aims to minimize long-term maintenance-related costs, including system failure costs. We provide optimal maintenance planning and performance control for every system degradation state through Markov decision process modeling and a dynamic programming algorithm. Load-sharing, restricted maintenance capacity, maintenance setup costs, and the structural characteristics of the system are considered in the model, all of which influence the optimal maintenance and performance control policy. Regarding degradation management, reducing the difference in degradation levels between elements, e.g., replacing more-degraded elements first, can be cost-effective. However, increasing the difference in degradation by maintenance or performance control can also lower maintenance-related costs in specific situations, which is discussed in numerical experiments. We also illustrate structural insights regarding the proposed model, including sensitivity analyses of maintenance capacity, setup costs, and the difference between preventive and corrective replacement costs.

Design and Implementation of a Miniature Jellyfish-Inspired Robot

With the development of the global marine industry, the demand to investigate underwater environments using robots is increasing. Inspired by the unique structure and excellent swimming ability of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Aurelia aurita</i> , a miniature jellyfish-inspired robot is developed. The robot comprises a headshell, six tentacles, a primary drive component, two flywheel steering components, a lightweight foam block, a dsPIC control system, and an energy supply component. The tentacles are covered with a 0.1-mm-thick silicone membrane and modeled in the shape of an umbrella. The membrane is driven by a gear motor to mimic the contraction and expansion of the interior cavity of a jellyfish; it exhibits the swimming behavior via water jet propulsion. Three-dimensional swimming is achieved by the flywheel steering components following the conservation of angular momentum. A built-in LoRa communication module (433 MHz) enables a robust, real-time connection between the robot and a terrestrial console. The small-sized, lightweight jellyfish robot has a diameter of 110 mm and a height of 140 mm; it weighs 318 g and achieves autonomous swimming with low power consumption. The robot can be used for underwater signal relay, environmental monitoring, and geological investigations.

The prolactin receptor scaffolds Janus kinase 2 via co-structure formation with phosphoinositide-4,5-bisphosphate.

Class 1 cytokine receptors transmit signals through the membrane by a single transmembrane helix to an intrinsically disordered cytoplasmic domain that lacks kinase activity. While specific binding to phosphoinositides has been reported for the prolactin receptor (PRLR), the role of lipids in PRLR signaling is unclear. Using an integrative approach combining nuclear magnetic resonance spectroscopy, cellular signaling experiments, computational modeling, and simulation, we demonstrate co-structure formation of the disordered intracellular domain of the human PRLR, the membrane constituent phosphoinositide-4,5-bisphosphate (PI(4,5)P2) and the FERM-SH2 domain of the Janus kinase 2 (JAK2). We find that the complex leads to accumulation of PI(4,5)P2 at the transmembrane helix interface and that the mutation of residues identified to interact specifically with PI(4,5)P2 negatively affects PRLR-mediated activation of signal transducer and activator of transcription 5 (STAT5). Facilitated by co-structure formation, the membrane-proximal disordered region arranges into an extended structure. We suggest that the co-structure formed between PRLR, JAK2, and PI(4,5)P2 locks the juxtamembrane disordered domain of the PRLR in an extended structure, enabling signal relay from the extracellular to the intracellular domain upon ligand binding. We find that the co-structure exists in different states which we speculate could be relevant for turning signaling on and off. Similar co-structures may be relevant for other non-receptor tyrosine kinases and their receptors.

Isolation of Retinal Pigment Epithelial Cells from Guinea Pig Eyes.

This protocol describes the isolation of cells of the retinal pigment epithelium (RPE) from the eyes of young pigmented guinea pigs for potential application in molecular biology studies, including gene expression analyses. In the context of eye growth regulation and myopia, the RPE likely plays a role as a cellular relay for growth modulatory signals, as it is located between the retina and the two walls of the eye, such as the choroid and sclera. While protocols for isolating the RPE have been developed for both chicks and mice, these protocols have proven not to be directly translatable to the guinea pig, which has become an important and widely used mammalian myopia model. In this study, molecular biology tools were used to examine the expression of specific genes to confirm that the samples were free of contamination from the adjacent tissues. The value of this protocol has already been demonstrated in an RNA-Seq study of RPE from young pigmented guinea pigs exposed to myopia-inducing optical defocus. Beyond eye growth regulation, this protocol has other potential applications in studies of retinal diseases, including myopic maculopathy, one of the leading causes of blindness in myopes, in which the RPE has been implicated. The main advantage of this technique is that it is relatively simple andonce perfected, yields high-quality RPE samples suitable for molecular biology studies, including RNA analysis.

The building blocks of caveolae revealed: caveolins finally take center stage.

The ability of cells to divide, migrate, relay signals, sense mechanical stimuli, and respond to stress all rely on nanoscale invaginations of the plasma membrane known as caveolae. The caveolins, a family of monotopic membrane proteins, form the inner layer of the caveolar coat. Caveolins have long been implicated in the generation of membrane curvature, in addition to serving as scaffolds for signaling proteins. Until recently, however, the molecular architecture of caveolins was unknown, making it impossible to understand how they operate at a mechanistic level. Over the past year, two independent lines of evidence - experimental and computational - have now converged to provide the first-ever glimpse into the structure of the oligomeric caveolin complexes that function as the building blocks of caveolae. Here, we summarize how these discoveries are transforming our understanding of this long-enigmatic protein family and their role in caveolae assembly and function. We present new models inspired by the structure for how caveolins oligomerize, remodel membranes, interact with their binding partners, and reorganize when mutated. Finally, we discuss emerging insights into structural differences among caveolin family members that enable them to support the proper functions of diverse tissues and organisms.

Controlling periodic long-range signalling to drive a morphogenetic transition.

Cells use signal relay to transmit information across tissue scales. However, the production of information carried by signal relay remains poorly characterised. To determine how the coding features of signal relay are generated, we used the classic system for long-range signalling: the periodic cAMP waves that drive Dictyostelium collective migration. Combining imaging and optogenetic perturbation of cell signalling states, we find that migration is triggered by an increase in wave frequency generated at the signalling centre. Wave frequency is regulated by cAMP wave circulation, which organises the long-range signal. To determine the mechanisms modulating wave circulation, we combined mathematical modelling, the general theory of excitable media, and mechanical perturbations to test competing models. Models in which cell density and spatial patterning modulate the wave frequency cannot explain the temporal evolution of signalling waves. Instead, our evidence leads to a model where wave circulation increases the ability for cells to relay the signal, causing further increase in the circulation rate. This positive feedback between cell state and signalling pattern regulates the long-range signal coding that drives morphogenesis.