Photonic generation of Terahertz (THz) carriers displays high potential for THz communications with a large tunable range and high modulation bandwidth. While many photonics-based THz generations ...have recently been demonstrated with discrete bulky components, their practical applications are significantly hindered by the large footprint and high energy consumption. Herein, we present an injection-locked heterodyne source based on generic foundry-fabricated photonic integrated circuits (PIC) attached to a uni-traveling carrier photodiode generating high-purity THz carriers. The generated THz carrier is tunable within the range of 0-1.4 THz, determined by the wavelength spacing between the two monolithically integrated distributed feedback (DFB) lasers. This scheme generates and transmits a 131 Gbits
net rate signal over a 10.7-m distance with -24 dBm emitted power at 0.4 THz. This monolithic dual-DFB PIC-based THz generation approach is a significant step towards fully integrated, cost-effective, and energy-efficient THz transmitters.
Migration plays a critical role in the evolution of cooperation under the framework of evolutionary game theory. Previous studies have demonstrated that individuals might make their migration ...decisions based on various information, for example, their current cooperative environments, potential advantages of new places, and their own aspirations. In reality, people may perceive environment information and make decisions based on these information. In this paper, we introduce an environment-driven migration into evolutionary public goods games which are carried out on a two-dimensional plane, where individuals decide whether to migrate according to the probabilities determined by the differences between the local and global cooperative environments. We find that such an environment-driven migration can effectively enhance cooperation. Furthermore, there exists an optimal migration noise that leads to a highest cooperation level. In addition, we also find that appropriate moving speeds and migration tendencies, as well as relatively low population densities in the model are more favorable to the evolution of cooperation.
Graphic Abstract
Considering the situation that environmental issues become more serious day by day, research on practical applications of semiconductor photocatalysis for environmental purification has attracted ...broad attention, including the remediation of water pollution, air contaminant treatment, photocatalytic sterilization
etc.
, among which the application of semiconductor photocatalytic properties for the disinfection of soil surfaces, air and water, such as TiO
2
, is of great interest. In this paper, we give an overview of the photocatalytic antibacterial ability of TiO
2
and other novel carbon material semiconductors. We have introduced the background information of photocatalytic disinfection and the disinfection mechanism of pure TiO
2
. Furthermore, other modified TiO
2
sterilization materials are listed, such as those with doping modification. In addition, some novel carbon based nanomaterials are discussed as well in this review, for instance, g-C
3
N
4
, carbon nanotubes and graphene nanosheets. Finally, we present an outlook over two dimensional (2D) materials and coupling techniques based on the combination of photocatalysis and other sterilization technologies.
With increasingly serious environmental issues, practical applications of semiconductor photocatalysts for environmental purification have attracted broad attention. Semiconductor photocatalysts for the disinfection of soil surfaces, air and water are of great interest.
Client-side optics are facing an ever-increasing upgrading pace, driven by upcoming 5G related services and datacenter applications. The demand for a single lane data rate is soon approaching 200 ...Gbps. To meet such high-speed requirement, all segments of traditional intensity modulation direct detection (IM/DD) technologies are being challenged. The characteristics of electrical and optoelectronic components and the performance of modulation, coding, and digital signal processing (DSP) techniques are being stretched to their limits. In this context, we witnessed technological breakthroughs in several aspects, including development of broadband devices, novel modulation formats and coding, and high-performance DSP algorithms for the past few years. A great momentum has been accumulated to overcome the aforementioned challenges. In this article, we focus on IM/DD transmissions, and provide an overview of recent research and development efforts on key enabling technologies for 200 Gbps per lane and beyond. Our recent demonstrations of 200 Gbps short-reach transmissions with 4-level pulse amplitude modulation (PAM) and discrete multitone signals are also presented as examples to show the system requirements in terms of device characteristics and DSP performance. Apart from digital coherent technologies and advanced direct detection systems, such as Stokes-vector and Kramers-Kronig schemes, we expect high-speed IM/DD systems will remain advantageous in terms of system cost, power consumption, and footprint for short reach applications in the short- to mid- term perspective.
In this paper, we study the problem of data gathering with compressive sensing (CS) in wireless sensor networks (WSNs). Unlike the conventional approaches, which require uniform sampling in the ...traditional CS theory, we propose a random walk algorithm for data gathering in WSNs. However, such an approach will conform to path constraints in networks and result in the non-uniform selection of measurements. It is still unknown whether such a non-uniform method can be used for CS to recover sparse signals in WSNs. In this paper, from the perspectives of CS theory and graph theory, we provide mathematical foundations to allow random measurements to be collected in a random walk based manner. We find that the random matrix constructed from our random walk algorithm can satisfy the expansion property of expander graphs. The theoretical analysis shows that a k-sparse signal can be recovered using `1 minimization decoding algorithm when it takes m = O(k log(n=k)) independent random walks with the length of each walk t = O(n=k) in a random geometric network with n nodes. We also carry out simulations to demonstrate the effectiveness of the proposed scheme. Simulation results show that our proposed scheme can significantly reduce communication cost compared to the conventional schemes using dense random projections and sparse random projections, indicating that our scheme can be a more practical alternative for data gathering applications in WSNs.
In this paper, we investigate power-efficient directed preconfigured cycles (p-Cycles) for asymmetric traffic protection in elastic optical networks (EONs) against single link failure. Owing to the ...advantage of distinguishing traffic amount in two directions, directed p-cycles consume low power by allocating different spectrum slots and modulation formats for each direction. A mixed integer linear programming (MILP) model is formulated to minimize total power consumption, which takes into account directed cycle generation, spectrum allocation, modulation adaptation, and protection capacity. To increase the scalability, the MILP model is decomposed, and a two-step approach is proposed: improved cycle enumeration and a simplified integer linear programming model. Extensive simulations are performed to study the power consumption of p-cycles under different traffic patterns in terms of traffic asymmetry (TASY), anycast ratio (AR), and the number of data centers (DCs). The results strongly demonstrate that directed p-cycles obtain significant power savings for protecting asymmetric traffic in EONs. The power savings rise up to 46.91% and 36.38% compared with undirected p-cycles as the TASY and AR increase, respectively. Moreover, the directed p-cycles achieve valuable power savings (up to 46.1%) with the introduction of DCs while the amount of power savings does not depend on the number of DCs.
We propose a cost-effective and memory-aware end-to-end learning scheme utilizing bi-directional gated recurrent unit (bi-GRU) for geometric constellation shaping (GCS) under the first-order regular ...perturbation (FRP) auxiliary channel. The performance of the proposed system has been numerically verified at a 32 GBd 5-channel wavelength division multiplexing (WDM) 64 quadrature amplitude modulation (QAM) 800 km optical coherent communication system. Results show that the proposed bi-GRU based GCS scheme can achieve a performance gain over square 64QAM in mutual information (MI) with 0.12 bits/symbol and a Q-factor gain of 0.4 dB at optimal launched optical power. When transmission distance is extended to 1280 km, a generalized mutual information (GMI) gain of 0.136 bits/symbol is observed. Additionally, compared with the bi-directional long short-term memory (bi-LSTM) based GCS, the proposed bi-GRU scheme has lower computation complexity with similar system performance.
In this letter, a new protection technique, namely Spectrum Shared pre-configured cycles (SS-p-cycles), is proposed for survivable elastic optical networks. SS-p-cycles permit to cut spectrum usage ...and spectrum fragmentation ratio (SFR) by leveraging special spectrum sharing among multiple p-cycles that have common link(s). To compute SS-p-cycles, we first formulate an integer linear programming model to obtain the optimal solution in small instance, and then develop a time-efficient heuristic algorithm to solve large-scale instances. Simulation results have demonstrated that the proposed SS-p-cycles outperform conventional p-cycles without spectrum sharing in terms of spectrum usage and SFR.
Even though elastic optical networks (EONs) are promising to provision increasingly dynamic and heterogeneous traffic, the requirements on bandwidth-variable optical devices bring upgrading ...challenges in current wavelength-division multiplexing (WDM) optical networks. Mixed-line-rate (MLR) optical networks offer a transitional solution that allows several coexisting line rates (e.g., 10/40/100 Gb/s). In this paper, we investigate distance-adaptive preconfigured-cycle (pCycle) protection scheme in MLR optical networks. Path-length-limited p-cycles are designed to be assigned line rate depending on the length of each protection path. Instead of conventional candidate cycle enumeration, a mixed integer linear programming (MILP) model is formulated to directly generate the optimal p-cycles with the minimum capital expenditures (CAPEX) cost. We also develop two algorithms to make the proposed MILP model scalable. Simulation results indicate that the algorithms are time efficient for solving the MILP-based p-cycle design. We further compare our p-cycle design method with other schemes, and demonstrate that our method largely reduces the CAPEX cost for more than 40%, mainly in transponder cost. To the best of our knowledge, this is the first time that distance-adaptive p-cycle design without candidate cycle enumeration is proposed for MLR optical networks.
Morphine dependence, a devastating neuropsychiatric condition, may be closely associated with gut microbiota dysbiosis. Ginsenoside Rg1 (Rg1), an active ingredient extracted from the roots of Panax ...ginseng C.A. Meyer, has potential health-promoting effects on the nervous system. However, its role in substance use disorders remains unclear. Here, we explored the potential modulatory roles of Rg1 in protection against morphine dependence.
Conditioned place preference (CPP) was used for establishing a murine model of morphine dependence. 16S rRNA gene sequencing and metabolomics were performed for microbial and metabolite analysis. Molecular analysis was tested for evaluating the host serum and brain responses.
Rg1 prevented morphine-induced CPP in mice. The 16S rRNA gene-based microbiota analysis demonstrated that Rg1 ameliorated morphine-induced gut microbiota dysbiosis, specifically for Bacteroidetes. Moreover, Rg1 also inhibited gut microbiota-derived tryptophan metabolism and reduced the serotonin, 5-hydroxytryptamine receptor 1B (5-HTR1B), and 5-hydroxytryptamine receptor 2 A (5-HTR2A) levels. However, the Rg1-induced amelioration of CPP was not observed in mice when their gut microbiome was depleted by non-absorbable antibiotics. Subsequently, gavage with Bacteroides vulgatus increased the abundance of Bacteroidetes. B. vulgatus supplementation synergistically enhanced Rg1-alleviated morphine-induced CPP in mice with microbiome knockdown. Co-treatment with B. vulgatus and Rg1 produced suppressive effects against morphine dependency by inhibiting tryptophan metabolism and reducing the serotonin and 5-HTR1B/5-HTR2A levels.
The gut microbiota-tryptophan metabolism-serotonin plays an important role in gut–brain signaling in morphine disorders, which may represent a novel approach for drug dependence treatment via manipulation of the gut microbial composition and tryptophan metabolite.
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•Ginsenoside Rg1 inhibit morphine dependence in mice.•Inhibition of ginsenoside Rg1 on morphine-dependent mice is associated with gut microbiota and tryptophan metabolism.•Bacteroides vulgaris synergistically enhanced ginsenoside Rg1 inhibit morphine dependence in mice.
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