Underwater wireless optical communication (UWOC) has received widespread attention recently due to its advantages in terms of high bandwidth, low power consumption and low delay. However, unlike ...underwater acoustic communication systems, the underwater wireless optical communication system is limited by its short communication range. In order to enlarge its application domain, it requires relaying and routing technology to achieve long-distance high bandwidth reliable transmissions (e.g., real-time video streaming). Although pre-deploying large number of sensor nodes is one of the possible solutions, this is impractical in response to emergency events such as oil pipeline leakage and shipwreck recovery. To this end, in this paper, we leverage swarms of autonomous underwater vehicles (AUVs) to build underwater optical communication links to transfer real-time video streaming. We first model the optical transmission channel considering solar noise, and then calculate both the optical communication angle and the reliable communicating range that satisfy a pre-defined bit error rate (BER). We then formulate the deployment optimization problem while targeting on minimizing both deployment energy consumption and delay. We also take positioning errors of AUVs into account to guarantee reliable communications. We provide an energy efficient algorithm to solve the formulated deployment problem. Through extensive simulations, we show that the algorithm effectively improves the deployment performance and achieves reliable communications.
To implement high-speed wireless communication from the deep ocean to the sea surface leveraging multiple autonomous underwater vehicles (AUVs) with underwater wireless optical communication (UWOC) ...technique is an emerging and promising technology that enables real-time data collection for accurate underwater exploration and monitoring, e.g., coordinated moving targets tracking. However, multi-hop UWOC is more susceptible to beam misalignment and positional uncertainty caused by external interference in the harsh marine environments. To address these challenges, we design a cooperative movement scheme for multiple AUVs based on deep reinforcement learning (DRL) approach to realize robust and reliable optical communication under mobile target tracking scenarios. In this scheme, we first model the optical channel with optical noise and then analyze the link performance of multiple AUVs to meet the bit error rate (BER) requirements. Afterwards, we map the cooperative optical communication problem to a Markov decision process (MDP) by incorporating the extended Kalman filter (EKF) technique to enhance effective communication. Finally, we propose a cooperative control strategy for multiple mobile AUVs based on deep deterministic policy gradient (DDPG). Through extensive simulations, it is demonstrated that the proposed algorithm is effective in achieving reliable underwater optical communication under mobile scenarios.
In marine wireless sensor networks, swarms of unmanned aerial vehicles (UAVs) based optical communication system can be leveraged to transmit underwater real-time monitoring data which enables a ...variety of potential maritime missions, such as video streaming for underwater surveillance and target tracking. However, due to the high directionality of optical beams and the mechanical instability of UAVs caused by the wind, the optical link via UAVs as relays is very fragile. To deal with the challenge, in this study, we model the problem as a partially observed Markov decision process (POMDP), and propose a novel link maintenance scheme based on the cooperative multi-agent deep deterministic policy gradient (MADDPG) approach to control the swarms of UAVs, which integrates the UAV dynamics model and the optical communication model. In this scheme, multiple UAVs act as agents controlling their own states in real-time under the complex wind field, in order to keep mechanical stability through cooperation, and dynamically maintain the reliability of the optical links which maximize communication performance to achieve reliable end-to-end optical communication and reduce energy consumption. Through numerical simulations, it demonstrates that the proposed optimization scheme is effective and achieves robust performance in terms of communication quality and energy consumption.
Aims
The etiology of Parkinson's disease (PD) is complex and the mechanism is unclear. It has become a top priority to find common factors that induce and affect PD pathology. We explored the key ...role of hypoxia in promoting the pathological propagation of α‐synuclein (α‐syn) and the progression of PD.
Methods
We performed PD modeling by conducting intracranial stereotaxic surgery in the unilateral striatum of mice. We then measured protein aggregation in vitro. The rotarod and pole tests were employed next to measure the damage of the phenotype. Pathological deposition and autophagy were also observed by immunofluorescence staining and protein levels measured by western blotting.
Results
We demonstrated that short‐term hypoxia activated phosphorylated (p)‐α‐syn in mice. We confirmed that p‐α‐syn was more readily formed aggregates than α‐syn in vitro. Furthermore, we found that hypoxia promoted the activation and propagation of endogenous α‐syn, contributing to the earlier degeneration of dopaminergic neurons in the substantia nigra and the deposition of p‐α‐syn in our animal model. Finally, autophagy inhibition contributed to the above pathologies.
Conclusion
Hypoxia was shown to accelerate the pathological progression and damage phenotype in PD model mice. The results provided a promising research target for determining common interventions for PD in the future.
Hypoxic stress specifically promotes α‐synuclein (α‐syn) aggregation and propagation by inducing the conversion of endogenous α‐syn into p‐α‐syn, thereby accelerating α‐syn prefabricated fibrils‐induced loss of dopaminergic neurons in the substantia nigra and PD‐like behavioral deficits in mice.
•The selected proposals are utilized to calculate the background regions as the propagation seeds.•The texture and global structure of images are integrated to refine the saliency-detection ...results.•With ERW propagation, our method can distinguish salient objects from the background reliably.
Recently, many graph-based algorithms are applied in the research of saliency detection, which use the border of an image as a background query. This frequently leads to undesired errors and retrieval outputs when the boundaries of the salient objects concerned touch, or connect with, the image’s border. In this paper, a novel bottom-up saliency-detection algorithm is proposed to tackle and overcome the above issue. First, we utilize object proposals to collect the background seeds reliably. Then, the Extended Random Walk (ERW) algorithm is adopted to propagate the prior background labels to the rest of the pixels in an image. Finally, we refine the saliency map by taking both the textural and structure-information into consideration simultaneously. Experiments on publicly available data sets show that our proposed method achieves competitive results against the state-of-the-art approaches.
ETS-1 is a transcription factor that is a member of the E26 transformation-specific (ETS) family. Galanin receptor 2 (GalR2), a subtype of receptors of the neuropeptide galanin, has been shown to ...have an antidepressant-like effect after activation in rodents. Our previous study has shown that overexpression of ETS-1 increases the expression of GalR2 in PC12 phaeochromocytoma cells. However, whether ETS-1 has an antidepressant-like effect is still unclear. In this study, we found that chronic mild stress (CMS) decreased the expression of both ETS-1 and GalR2 in the ventral hippocampus of rats. Meanwhile, we demonstrated that overexpression of ETS-1 increased the expression of GalR2 in primary hippocampal neurons. Importantly, we showed that overexpression of ETS-1 in the ventral hippocampus counteracted the depression-like behaviors of CMS rats. Furthermore, we found that overexpression of ETS-1 increased the level of downstream phosphorylated extracellular signal-regulated protein kinases 1 and 2 (p-ERK1/2) of GalR2 in the ventral hippocampus of CMS rats. Taken together, our findings suggest that ETS-1 has an antidepressant-like effect in rats, which might be mediated by increasing the level of GalR2 and its downstream p-ERK1/2 in the ventral hippocampus.
Existing range-based localization schemes for under-water acoustic sensor networks (UASNs) rely on sufficient and accurate distance measurements. However, in practice, ranging packets are inevitably ...corrupted due to packet collisions and signal noises, resulting in missing and noisy distance measurements and further degrading localization performance significantly. In this paper, we propose a packet corruption tolerant localization algorithm to address this challenge. First, we design an energy-efficient mechanism to gather inter-node distance measurements and form partially observed Square Distance Matrix (SDM). Then, leveraging the intrinsic low-rank structure of SDM, the reconstruction of true SDM is formulated as a Frobenius-norm regularized matrix factorization problem and an improved Newton-Raphson method is designed to solve this problem. Finally, we apply Multi-Dimension Scaling technique to localize all the nodes based on the reconstructed SDM. Simulation results demonstrate that, our proposed algorithm outperforms the benchmark approaches in terms of localization accuracy, coverage and stability.
Galanin receptor1 (GalR1) transcript levels are elevated in the rat ventral periaqueductal gray (vPAG) after chronic mild stress (CMS) and are related to depression-like behavior. To explore the ...mechanisms underlying the elevated GalR1 expression, we carried out molecular biological experiments in vitro and in animal behavioral experiments in vivo. It was found that a restricted upstream region of the
gene, from -250 to -220, harbors an E-box and plays a negative role in the
promoter activity. The transcription factor Scratch2 bound to the E-box to down-regulate
promoter activity and lower expression levels of the
gene. The expression of Scratch2 was significantly decreased in the vPAG of CMS rats. Importantly, local knockdown of Scratch2 in the vPAG caused elevated expression of GalR1 in the same region, as well as depression-like behaviors. RNAscope analysis revealed that GalR1 mRNA is expressed together with Scratch2 in both GABA and glutamate neurons. Taking these data together, our study further supports the involvement of GalR1 in mood control and suggests a role for Scratch2 as a regulator of depression-like behavior by repressing the
gene in the vPAG.
Depression-like behavior in rat Wang, Peng; Li, Hui; Barde, Swapnali ...
Proceedings of the National Academy of Sciences - PNAS,
08/2016, Letnik:
113, Številka:
32
Journal Article
Recenzirano
Odprti dostop
The neuropeptide galanin coexists in rat brain with serotonin in the dorsal raphe nucleus and with noradrenaline in the locus coeruleus (LC), and it has been suggested to be involved in depression. ...We studied rats exposed to chronic mild stress (CMS), a rodent model of depression. As expected, these rats showed several endophenotypes relevant to depression-like behavior compared with controls. All these endophenotypes were normalized after administration of a selective serotonin reuptake inhibitor. The transcripts for galanin and two of its receptors, galanin receptor 1 (GALR1) and GALR2, were analyzed with quantitative real-time PCR using laser capture microdissection in the following brain regions: the hippocampal formation, LC, and ventral periaqueductal gray (vPAG). Only Galr1 mRNA levels were significantly increased, and only in the latter region. After knocking down Galr1 in the vPAG with an siRNA technique, all parameters of the depressive behavioral phenotype were similar to controls. Thus, the depression-like behavior in rats exposed to CMS is likely related to an elevated expression of Galr1 in the vPAG, suggesting that a GALR1 antagonist could have antidepressant effects.
Galanin receptor 2 (GAL2R) is a G protein-coupled receptor for the neuropeptide galanin that regulates many important physiological functions and pathological processes. To investigate the molecular ...mechanism governing
GAL2R
gene transcription, the rat
GAL2R
promoter was isolated and analyzed. We found that the region from −320 to −300 of the
GAL2R
promoter contains two putative ETS-1 elements and plays an important role in regulating
GAL2R
promoter activity. We also showed that transcription factor ETS-1 bound to this region in vitro and in vivo. Overexpression of ETS-1 significantly increased
GAL2R
promoter activity and transcription of the
GAL2R
gene, whereas knockdown of ETS-1 produced the opposite effects. In addition, we showed that ETS-1 recruited co-activator p300 to the
GAL2R
promoter. These data indicate a role for ETS-1 in the control of the
GAL2R
gene expression and provide a basis for understanding the transcriptional regulation of the
GAL2R
gene.
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