This article focuses on the issue of cooperative spectrum sensing (CSS) in a mobile energy-harvesting cognitive radio network (EH-CRN), where secondary transmitters (STs) are powered by the ...radio-frequency (RF) signal emitted from primary transmissions. Only the STs with sufficient energy participate in CSS, and send their local sensing decisions to a fusion center (FC), which makes a final decision on the state of the spectrum by a general <inline-formula> <tex-math notation="LaTeX">k </tex-math></inline-formula>-out-of-<inline-formula> <tex-math notation="LaTeX">M(k) </tex-math></inline-formula> fusion rule. The target of this article is to develop an optimal CSS strategy in terms of final decision threshold <inline-formula> <tex-math notation="LaTeX">k </tex-math></inline-formula> that maximizes the expected achievable throughput of the EH-CRN, subject to a collision constraint and an energy causality constraint. We first show that the EH-CRN can be divided into an energy-deficit state and a spectrum-deficit state depending on the final decision threshold. The final decision threshold has a negative correlation with the number of STs participating in CSS in the energy-deficit state, and has no impact on that in the spectrum-deficit state. We then derive the collision probability and the expected achievable throughput of the EH-CRN, both of which are indicated to be determined by the active probability of a ST, the state of the spectrum, and the spectrum access opportunity. By tackling the tradeoff between the active probability and spectrum access opportunity introduced by the final decision threshold, we derive the optimal final decision threshold that maximizes the expected achievable throughput of the EH-CRN while protecting primary transmissions to a predefined extent. Extensive numerical simulations are conducted to illustrate the performance versus the final decision threshold. One of the main findings indicates that the optimal range of final decision threshold in the energy-deficit state could be acquired by the number of reporting received at the FC.
In this study, a novel and fast maximum power point tracking (MPPT) algorithm for a photovoltaic generation system is proposed. The main idea is to remove the random number in the voltage calculation ...equation of the conventional cuckoo search method. The advantages of the proposed method include 1) fast maximum power point (MPP) tracking speed and high MPP tracking accuracy under both uniform insolation and partially shaded conditions (PSCs), 2) simple MPPT structure, and 3) consistent solution can be achieved with only three particles and only one parameter is required to be tuned. In order to validate the effectiveness and correctness of the proposed method, both simulation and experiments are carried out on a 300 W prototyping circuit. According to the experimental results, the proposed MPPT method can improve the tracking time by 46.42% and 11.76% comparing to conventional perturb and observe (P&O) and variable-step P&O technique, respectively. In addition, the proposed method can successfully track the global MPP in 249 of 252 different PSC patterns. The tracking accuracies under both uniform irradiance and PSC conditions are all higher than 99.8%.
Trend of dense deployment of 802.11 WLANs makes it urgent to design effective and efficient channel access schemes. IEEE 802.11ax standard for the next generation WLAN introduces the orthogonal ...frequency division multiple access (OFDMA) mechanism that supports downlink and uplink multi-user transmissions over multiple resource units (RUs). In this paper, we, integrating the multi-user transmissions with the target wake time (TWT) mechanism, propose the Scheduling Channel Access with TWT (SCAT) scheme. The SCAT wakes up stations (STAs) no more than the number of RUs in each target beacon so that the channel can be accessed on schedule without contention. Additionally, we develop a mathematical model to derive the throughput and delay arising from sleeping (DAFS) under the SCAT, which are used to formulate the throughput maximization problem (TMP) subject to delay constraint. Then, the TMP is solved by the genetic algorithm in which a tree is chosen as a chromosome. The solution to the TMP enables the SCAT to assign the optimal listen intervals and the next target beacons to the STAs so that the maximum throughput is achieved. Simulation results show the SCAT outperforms the existing schemes in throughput, channel utilization, and energy efficiency.
Neuroinflammation has been reported to be associated with Alzheimer's disease (AD) pathogenesis. Neuroinflammation is generally considered as an outcome of glial activation; however, we recently ...demonstrated that T helper (Th)17 cells, a subpopulation of proinflammatory CD4+ T cells, are also involved in AD pathogenesis. Transforming growth factor (TGF)-β1, a cytokine that can be expressed in the brain, can be immunosuppressive, but its effects on lymphocyte-mediated neuroinflammation in AD pathogenesis have not been well addressed. In the current study we administered TGF-β1 via intracerebroventricle (ICV) and intranasal (IN) routes in AD model rats to investigate its antiinflammatory and neuroprotective effects. The AD rat model was prepared by bilateral hippocampal injection of amyloid-β (Aβ)1-42. TGF-β1 was administered via ICV one hour prior to Aβ1-42 injection or via both nares seven days after Aβ1-42 injection. ICV administration of TGF-β1 before Aβ1-42 injection remarkably ameliorated Aβ1-42-induced neurodegeneration and prevented Aβ1-42-induced increases in glia-derived proinflammatory mediators (TNF-α, IL-1β and iNOS), as well as T cell-derived proinflammatory cytokines (IFN-γ, IL-2, IL-17 and IL-22), in the hypothalamus, serum or cerebrospinal fluid (CSF) in a concentration-dependent manner. TGF-β1 pretreatment also prevented Aβ1-42-induced decreases in the neurotrophic factors, IGF-1, GDNF and BDNF, and in the antiinflammatory cytokine, IL-10. Similarly, IN administration of TGF-β1 after Aβ1-42 injection reduced neurodegeneration, elevation of proinflammatory mediators and cytokines, and reduction of neurotrophic and antiinflammatory factors, in the hypothalamus, serum or CSF. These findings suggest that TGF-β1 suppresses glial and T cell-mediated neuroinflammation and thereby alleviates AD-related neurodegeneration. The effectiveness of IN administered TGF-β1 in reducing Aβ1-42 neurotoxicity suggests a possible therapeutic approach in patients with AD.
Single‐housed stress elicits a range of social isolation‐related behavioral and neurobiological abnormalities. To investigate single housing‐induced behavioral changes and sex differences on stress ...outcomes, we examined single‐housed stress‐induced learning and memory impairment, depression‐like behaviors, neuroplasticity abnormalities and underlying mechanism. The results showed that male and female mice socially isolated for 8 weeks had significantly decreased memory acquisition, as demonstrated in the learning curve of the Morris water maze task. Memory consolidation and retrieval were also decreased in both the single‐housed male and female mice. These findings were corroborated further by the two classical animal models, Y‐maze and novel object recognition tests, as demonstrated by reduced spontaneous alternation and recognition index in both sexes of single‐housed mice. Subsequent studies suggested that single‐housed male mice exhibited increased immobility time in both the forced swim and tail suspension tests, while the female mice only exhibited increased immobility time in the tail suspension test. Moreover, single‐housed stress significantly decreased the apical and basal branch points, dendritic length, and spine density in the CA1 of hippocampal neurons in both male and female mice. These effects were consistent with decreased neuroplasticity and neuroprotective‐related molecules such as synaptophysin, PSD95, PKA, pCREB and BDNF expression. These findings suggest that loss of neuronal remodeling and neuroprotective mechanisms due to single housing are involved in behavioral changes in both male and female mice. The results provide further evidence that neuroplasticity‐related signaling plays a crucial role in isolation‐induced effects on neuropsychiatric behavioral deficits in both sexes.
To investigate single housing‐induced behavioral changes and sex differences on stress outcomes, we examined single‐housed stress‐induced learning and memory impairment, depression‐like behaviors, neuroplasticity abnormalities and underlying mechanism. The data suggest that loss of neuronal remodeling and neuroprotective mechanisms are involved in behavioral changes in female and male mice after single housing. The results provide further evidence that neuroplasticity‐related signaling plays a crucial role in stress‐related disorders such as depression and cognitive deficits.
The exotic photophysical properties of organic–inorganic hybrid perovskite with long exciton lifetimes and small binding energy have appeared as promising front‐runners for next‐generation ...non‐volatile flash photomemory. However, the long photo‐programming time of photomemory limits its application on light‐fidelity (Li‐Fi), which requires high storage capacity and short programming times. Herein, the spatially addressable perovskite in polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO)/perovskite composite film as an photoactive floating gate is demonstrated to elucidate the effect of morphology on the photo‐responsive characteristics of photomemory. The chelation between lead ion and PEO segment promotes the anti‐solvent functionalities of the perovskite/PS‐b‐PEO composite film, thus allowing the solution‐processable poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) to act as the active channel. Through manipulating the interfacial area between perovskite and P3HT, fast photo‐induced charge transfer rate of 0.056 ns−1, high charge transfer efficiency of 89%, ON/OFF current ratio of 104, and extremely low programming time of 5 ms can be achieved. This solution‐processable and fast photo‐programmable non‐volatile flash photomemory can trigger the practical application on Li‐Fi.
The spatially addressable perovskite in a polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO)/perovskite composite film as an photoactive floating gate is demonstrated. By manipulating the interfacial area between the perovskite and active channel, a fast photo‐induced charge transfer rate of 0.056 ns−1, high charge transfer efficiency of 89%, ON/OFF current ratio of 104, and extremely low programming time of 5 ms can be achieved.
Alzheimer's disease (AD) is one of the major disabling and lethal diseases for aged individuals worldwide. To date, there are more than 10 hypotheses proposed for AD pathology. The beta-amyloid (Aβ) ...cascade hypothesis is the most widely accepted and proposes that the accumulation of Aβ in the brain is one potential mechanism for AD pathogenesis. Because some Aβ-overloaded patients do not have AD syndrome, this hypothesis is challenged from time to time. More recently, it has been shown that intracellular Aβ plays a key role in AD pathology. Aβ is internalized by receptors distributed on the cell membrane. Among these receptors, the alpha7 nicotinic acetylcholine receptor (α7 nAChR) has been shown to play an important role in AD. The α7 nAChR is a ligand-gated ion channel and is expressed in pivotal brain regions (e.g., the cerebral cortex and hippocampus) responsible for cognitive functions. The α7 nAChR is localized both presynaptically and postsynaptically, where it activates intracellular signaling cascades. Its agonist has been investigated in clinical studies to improve cognitive functions in AD. Although many studies have shown the importance of the α7 nAChR in AD, little is known regarding its role in AD pathology. Therefore, in the current review, we summarized the basic information regarding the structures and functions of the α7 nAChR, the distribution and expression of the α7 nAChR, and the role of the α7 nAChR in mediating Aβ internalization. We subsequently focused on introducing the comprehensive α7 nAChR related signaling pathways and how these signaling pathways are integrated with the α7 nAChR to play a role in AD. Finally, we stressed the AD therapy that targets the α7 nAChR.
•Intracellular Aβ is an early pathological marker in AD patients and AD-like animal.•The α7nAChR agonist rescues the Aβ induced neurotoxicity.•NF-κB/TNF/CDK5, MAPK, JAK, NOS etc. are related to Aβ induced neurotoxicity.•The α7nAChR-mediated neuroprotection is achieved via JAK2/STAT3 etc. pathway.•The α7nAChR could be aimed as a therapeutic target in AD.
The faithful storage and coherent manipulation of quantum states with matter-systems would enable the realization of large-scale quantum networks based on quantum repeaters. To achieve useful ...communication rates, highly multimode quantum memories are required to construct a multiplexed quantum repeater. Here, we present a demonstration of on-demand storage of orbital-angular-momentum states with weak coherent pulses at the single-photon-level in a rare-earth-ion-doped crystal. Through the combination of this spatial degree-of-freedom (DOF) with temporal and spectral degrees of freedom, we create a multiple-DOF memory with high multimode capacity. This device can serve as a quantum mode converter with high fidelity, which is a fundamental requirement for the construction of a multiplexed quantum repeater. This device further enables essentially arbitrary spectral and temporal manipulations of spatial-qutrit-encoded photonic pulses in real time. Therefore, the developed quantum memory can serve as a building block for scalable photonic quantum information processing architectures.
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