Mark ratio modulation over pulse position modulation

Orthogonal modulation superimposes non-amplitude-modulated signals on Manchester coded or pulse position modulated amplitude shift keying (ASK) signals, allowing two traffic flows with different bit rates to be modulated on the same wavelength channel, and hence improving spectrum efficiency. Inspired by the orthogonal modulation, this paper proposes a novel modulation format, i.e., mark ratio modulation over pulse position modulation (PPM), which utilizes the mark ratio difference between the PPM symbols and the inverse PPM symbols to deliver an overlaid signal. Better than traditional orthogonal modulation, in the mark ratio modulation over PPM, both low-speed and high-speed traffic flows are modulated by ASK with no need to sacrifice the extinction ratio, while keeping the reception simple and easy. According to theoretical analysis and test, we found 4PPM is a good option, which can balance the trade-off between the PPM signal\u27s effective bit rate and the mark ratio modulated signal\u27s quality

Ordered Semiconducting Nitrogen-Graphene Alloys

The interaction between substitutional nitrogen atoms in graphene is studied by performing first principles calculations. The nearest neighbor interaction between nitrogen dopants is highly repulsive because of the strong electrostatic repulsion between nitrogen atoms, which prevents the full phase separation in nitrogen doped graphene. Interestingly, there are two relatively stable nitrogen-nitrogen pairs due to the anisotropy charge redistribution induced by nitrogen doping. We reveal two stable semiconducting ordered N doped graphene structures C3N and C12N through the cluster expansion technique and particle swarm optimization method. In particular, C12N has a direct band gap of 0.98 eV. The heterojunctions between C12N and graphene nanoribbons might be promising organic solar cells

MRI Lesion Load of Cerebral Small Vessel Disease and Cognitive Impairment in Patients With CADASIL

Background and objective: Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the best known and the most common monogenic small vessel disease (SVD). Cognitive impairment is an inevitable feature of CADASIL. Total SVD score and global cortical atrophy (GCA) scale were found to be good predictors of poor cognitive performance in community-dwelling adults. We aimed to estimate the association between the total SVD score, GCA scale and the cognitive performance in patients with CADASIL.Methods: We enrolled 20 genetically confirmed CADASIL patients and 20 controls matched by age, gender, and years of education. All participants underwent cognitive assessments to rate the global cognition and individual domain of executive function, information processing speed, memory, language, and visuospatial function. The total SVD score and GCA scale were rated.Results: The CADASIL group performed worse than the controls on all cognition measures. Neither global cognition nor any separate domain of cognition was significantly different among patients grouped by total SVD score. Negative correlations between the GCA score and cognitive performance were observed. Approximately 40% of the variance was explained by the total GCA score in the domains of executive function, information processing speed, and language. The superficial atrophy score was associated with poor performance in most of the domains of cognition. Adding the superficial atrophy score decreased the prediction power of the deep atrophy score on cognitive impairment alone.Conclusions: The GCA score, not the total SVD score, was significantly associated with poor cognitive performance in patients with CADASIL. Adding the superficial atrophy score attenuated the prediction power of the deep atrophy score on cognitive impairment alone

Research on Regional Trunk Logistics Operating Cost

In order to ensure the balance of trunk transportation resources, logistics enterprises generally require transport vehicles to return to the initial distribution after completing the transportation task, so as to facilitate the next phase of transportation operations. Most logistics enterprises waste the trunk transportation resources in the whole process of logistics transportation. At this time, we need to choose a comprehensive transportation network optimization method to improve the vehicle loading rate, reduce the transportation cost, and design a new form of trunk transportation network. The article analyzes the operation flow of trunk transportation logistics

An intrusion detection approach based on improved deep belief network

In today's interconnected society, cyberattacks have become more frequent and sophisticated, and existing intrusion detection systems may not be adequate in the complex cyberthreat landscape. For instance, existing intrusion detection systems may have overfitting, low classification accuracy, and high false positive rate (FPR) when faced with significantly large volume and variety of network data. An intrusion detection approach based on improved deep belief network (DBN) is proposed in this paper to mitigate the above problems, where the dataset is processed by probabilistic mass function (PMF) encoding and Min-Max normalization method to simplify the data preprocessing. Furthermore, a combined sparsity penalty term based on Kullback-Leibler (KL) divergence and non-mean Gaussian distribution is introduced in the likelihood function of the unsupervised training phase of DBN, and sparse constraints retrieve the sparse distribution of the dataset, thus avoiding the problem of feature homogeneity and overfitting. Finally, simulation experiments are performed on the NSL-KDD and UNSW-NB15 public datasets. The proposed method achieves 96.17% and 86.49% accuracy, respectively. Experimental results show that compared with the state-of-the-art methods, the proposed method achieves significant improvement in classification accuracy and FPR

Synthesis of a MnO2–graphene foam hybrid with controlled MnO2 particle shape and its use as a supercapacitor electrode

A simple approach was developed to synthesize the three-dimensional (3D) hybrid of manganese dioxide (MnO2) and graphene foam. The morphology of the MnO2 nanostructures can be readily controlled by the solution acidity. Furthermore, we demonstrate that, serving as a free-standing supercapacitor electrode, this novel three-dimensional hybrid gives a remarkable specific capacitance (560 F/g at the current density of 0.2 A/g) and excellent cycling stability

Supercapacitor electrode based on three-dimensional graphene–polyaniline hybrid

Three-dimensional (3D) graphene was synthesized by chemical vapour deposition with nickel foam as a substrate. Based on the 3D graphene foams, free-standing graphene–polyaniline (PANI) hybrids were produced by in-situ polymerization of aniline monomer under acid condition, and characterized by scanning electron microscopy (SEM), Fourier transformation infrared (FTIR), and Raman spectroscopy. Furthermore, we show that supercapacitor electrodes based on the 3D graphene–PANI hybrid exhibit high specific capacitances (346 Fg−1 at a discharge current density of 4 Ag−1), suggesting that the light and inexpensive 3D graphene foams are a promising candidate for energy storage

WO₃ Nanoflakes for Enhanced Photoelectrochemical Conversion

We developed a postgrowth modification method of two-dimensional WO₃ nanoflakes by a simultaneous solution etching and reducing process in a weakly acidic condition. The obtained dual etched and reduced WO₃ nanoflakes have a much rougher surface, in which oxygen vacancies are created during the simultaneous etching/reducing process for optimized photoelectrochemical performance. The obtained photoanodes show an enhanced photocurrent density of ∼1.10 mA/cm² at 1.0 V <i>vs</i> Ag/AgCl (∼1.23 V <i>vs</i> reversible hydrogen electrode), compared to 0.62 mA/cm² of pristine WO₃ nanoflakes. The electrochemical impedance spectroscopy measurement and the density functional theory calculation demonstrate that this improved performance of dual etched and reduced WO₃ nanoflakes is attributed to the increase of charge carrier density as a result of the synergetic effect of etching and reducing

Solar-Driven Photoelectrochemical Probing of Nanodot/Nanowire/Cell Interface

We report a nitrogen-doped carbon nanodot (N-Cdot)/TiO₂ nanowire photoanode for solar-driven, real-time, and sensitive photoelectrochemical probing of the cellular generation of H₂S, an important endogenous gasotransmitter based on a tunable interfacial charge carrier transfer mechanism. Synthesized by a microwave-assisted solvothermal method and subsequent surface chemical conjugation, the obtained N-Cdot/TiO₂ nanowire photoanode shows much enhanced photoelectrochemical photocurrent compared with pristine TiO₂ nanowires. This photocurrent increase is attributed to the injection of photogenerated electrons from N-Cdots to TiO₂ nanowires, confirmed by density functional theory simulation. In addition, the charge transfer efficiency is quenched by Cu²⁺, whereas the introduction of H₂S or S^2– ions resets the charge transfer and subsequently the photocurrent, thus leading to sensitive photoelectrochemical recording of the H₂S level in buffer and cellular environments. Moreover, this N-Cdot-TiO₂ nanowire photoanode has been demonstrated for direct growth and interfacing of H9c2 cardiac myoblasts, with the capability of interrogating H₂S cellular generation pathways by vascular endothelial growth factor stimulation as well as inhibition