Peripheral actions and direct central-local communications of melanocortin 4 receptor signaling

Melanocortin 4 receptor(MC4R),the most important monogenetic cause of human metabolic disorders,has been of great interest to many researchers in the field of energy homeostasis and public health.Because MC4R is a vital pharmaceutical target for maintaining controllable appetite and body weight for professional athletes,previous studies have mainly focused on the central,rather than the peripheral,roles of MC4R.Thus,the local expression of MC4R and its behavioral regulation remain unclear.In an attempt to shed light on different directions for future studies of MC4R signaling,we review a series of recent and important studies exploring the peripheral functions of MC4R and the direct physiological interaction between peripheral organs and central MC4R neurons in this article.

Ambiguity function analysis and side peaks suppression of Link16 signal based passive radar

Link16 data link is the communication standard of the joint tactical information distribution system(JTIDS)used by the U.S.military and North Atlantic Treaty Organization,which is applied as the opportunistic illuminator for passive radar in this paper.The time-domain expression of the Link16 signal is established,and its ambiguity function expression is derived.The timedelay dimension and Doppler dimension side peaks of which lead to the appearance of the false target during target detection.To solve the problem,the time-delay dimension and Doppler dimension side peaks suppression methods are proposed.For the problem that the conventional mismatched filter(MMF)cannot suppress the time-delay dimension side peaks,a neighborhood MMF(NMMF)is proposed.Experimental results demonstrate the effectiveness of the proposed methods.

Approach to blind estimation of the PN sequence in DS-SS signals with residual carrier

This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise （PN） sequence estimation in low signal to noise ratios （SNR） direct sequence spread spectrum （DS-SS） signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR.

STUDY OF MISMATCHED FILTERING OF PASSIVE RADAR USING TV SIGNAL

This letter delnonstrates the structure of the passive radar using TV signals. Because the TV signal is a kind of pseudoperiodic signal, the matched filtering of color TV signals would yield high sidelobes which cause the range ambiguity. To overcome this problem, the mismatched filter is proposed to suppress the correlation sidelobcs of matched filtering of TV signals. By utilizing the iteration process, this method could achieve the required peak sidclobc level. The impacts of the noise and target movement on mismatched filtering are also analysed, Simulation results are included to demonstrate the effectiveness of the proposed technique.

The Wnt/β-catenin signaling pathway in the tumor microenvironment of hepatocellular carcinoma

The Wnt/β-catenin signaling pathway regulates many aspects of tumor biology,and many studies have focused on the role of this signaling pathway in tumor cells.However,it is now clear that tumor development and metastasis depend on the two-way interaction between cancer cells and their environment,thereby forming a tumor microenvironment(TME).In this review,we discuss how Wnt/β-catenin signaling regulates cross-interactions among different components of the TME,including immune cells,stem cells,tumor vasculature,and noncellular components of the TME in hepatocellular carcinoma.We also investigate their preclinical and clinical insights for primary liver cancer intervention,and explore the significance of using Wnt/β-catenin mutations as a biomarker to predict resistance in immunotherapy.

Delay Analysis and Formulation Inference of Signalized Intersection for Traffic Congestion Conditions

Vehicle delay is an important measure to evaluate the signal timings of signalized intersections.When optimization the signal control parameters, delays of vehicles from all approach directions of an intersection should be considered. Based on the analysis of the vehicle delay on an approach of intersection, directed against the typical condition of a congested intersection-over-saturated condition, the paper has analyzed and inferred the intersection delay dynamic formulation, and has established the relation between intersection delay,the signal timings, vehicle arrival rate and the queue lengths, and that provides useful information for understanding vehicle delay of signalized intersection and for establishing performance index function of signal timing optimization.

Sensorless Monitoring of a Motor-Drive Machanical System Based on Adaptive Signal Decomposition

A method for estimating current harmonics of an induction motor is introduced which is used for sensorless monitoring of a mechanical system driven by the motor. The method is based on an adaptive signal representation and is proposed to extract weak harmonics from a noisy current signal, especially in the presence of additive interference caused by transient modulation waves. As an application, a rotor unbalance experiment of rotating machinery driven by an induction motor is carried out, The result shows that the eccentricity harmonic magnitude of a current signal obtained by the method represents the rotor unbalance conditions sensitively. Vibration analysis is used to validate the proposed method.

Analysis of an improved acquisition method for high-dynamic BOC signal

To reach a compromise between short acquisition time and excellent detection probability for the high-dynamic binary offset carrier (BOC) signal, an overall algorithm based on discrete polynomial-phase transform (DPT) and partial matching filter (PMF)-fast Fourier transform (FFT) algorithm is given. The high order items of received signals are removed by the method of DPT, and the PMF-FFT algorithm is redesigned for the BOC signal. The simulation experiments and theoretical analyses verify that the improved algorithm has attained improvement in acquisition performance. © 2016 Beijing Institute of Aerospace Information.

Shp2-mediated molecular signaling in control of embryonic stem cell self-renewal and differentiation

A key issue to be addressed in stem cell biology is the molecular signaling mechanism controlling embryonic stem （ES） cell pluripotency. Stem cell properties are dictated by specific transcription factors and epigenetic processes such as DNA methylation and chromatin remodeling. Several cytokines/growth factors have been identified as critical ES cell regulators. However, there is a gap in our knowledge of the intracellular signaling pathways linking extracellular signals to transcriptional regulation in ES cells. This short review discusses the physiological role of Shp2, a cytoplasmic tyro- sine phosphatase, in the molecular switch governing ES cell self-renewal versus differentiation. Shp2 promotes ES cell differentiation, mainly through bi-directional modulation of Erk and Stat3 pathways. Deletion of Shp2 in mouse ES cells results in more efficient self-renewal. This observation provides the impetus to develop Shp2 inhibitors for maintenance and amplification of ES cells in culture.

Schizonepeta tenuifolia inhibits collagen stimulated platelet function via suppressing MAPK and Akt signaling

The prevalence of cardiovascular diseases(CVDs)is increasing at a rapid pace in developed countries,and CVDs are the leading cause of morbidity and mortality.Natural products and ethnomedicine have been shown to reduce the risk of CVDs.Schizonepeta(S.)tenuifolia is a medicinal plant widely used in China,Korea,and Japan and is known to exhibit anti-inflammatory,antioxidant,and immunomodulatory activities.We hypothesized that given herbal plant exhibit pharmacological activities against CVDs,we specifically explored its effects on platelet function.Platelet aggregation was evaluated using standard light transmission aggregometry.Intracellular calcium mobilization was assessed using Fura-2/AM,and granule secretion(ATP release)was measured in a luminometer.Fibrinogen binding to integrin a_(Ⅱb)β_3,was assessed using flow cytometry.Phosphorylation of mitogen-activated protein kinase(MAPK)signaling molecules and activation of the protein kinase B(Akt)was assessed using Western blot assays.S.tenuifolia,extract potently and significantly inhibited platelet aggregation,calcium mobilization,granule secretion,and fibrinogen binding to integrin a_(Ⅱb)β_3.Moreover,all extracts significantly inhibited MAPK and Akt phosphorylation.S.tenuifolia extract inhibited platelet aggregation and granule secretion,and attenuated collagen mediated GPVI downstream signaling,indicating the potential therapeutic effects of these plant extracts on the cardiovascular system and platelet function.We suggest that S.tenuifolia extract may be a potent candidate to treat platelet-related CVDs and to be used as an antiplatelet and antithrombotic agent.

DOA estimation of wideband signals based on iterative spectral reconstruction

In order to solve the problem of coherent signal subspace method(CSSM) depending on the estimated accuracy of signal subspace, a new direction of arrival(DOA) estimation method of wideband source, which is based on iterative adaptive spectral reconstruction, is proposed. Firstly, the wideband signals are divided into several narrowband signals of different frequency bins by discrete Fourier transformation(DFT). Then, the signal matched power spectrum in referenced frequency bins is computed, which can form the initial covariance matrix. Finally, the linear restrained minimum variance spectral(Capon spectral) of signals in other frequency bins are reconstructed using sequential iterative means, so the DOA can be estimated by the locations of spectral peaks. Theoretical analysis and simulation results show the proposed method based on the iterative spectral reconstruction for the covariance matrices of all sub-bands can avoid the problem of determining the signal subspace accurately with the coherent signal subspace method under the conditions of small samples and low signal to noise ratio(SNR), and it can also realize full dimensional focusing of different sub-band data, which can be applied to coherent sources and can significantly improve the accuracy of DOA estimation.

System Design and Signal Processing for Frequency Diverse Array Radar

Frequency diverse array(FDA)radar has been studied for more than 15 years and has attracted a lot of attention due to its potential advantages over the well-known phased array radar.The representative feature of FDA is range-angle-time-dependent transmit beampattern and its underlying properties are continuously revealed in the research.The formulation and exploitation of the transmit diversity with a frequency increment is the fundamental principle,which brings extra degrees-of-freedom(DOFs)in the transmit dimension.As the FDA radar carries additional information in range,it provides more flexibility in signal processing and also brings in new technical issues.This article overviews the state-of-the-art in FDA radar area and its applications,mainly based on the progress in our group.There are two main catalogs in FDA radar area,namely coherent FDA and FDA-MIMO(multiple-input multiple-output)radars.Potential applications including target parameter estimation,ambiguous clutter suppression,and deceptive jammer suppression are discussed.

Analysis of weak signal detection based on tri-stable system under Levy noise

Stochastic resonance system is an effective method to extract weak signal.However,system output is directly influenced by system parameters.Aiming at this,the Levy noise is combined with a tri-stable stochastic resonance system.The average signal-to-noise ratio gain is regarded as an index to measure the stochastic resonance phenomenon.The characteristics of tri-stable stochastic resonance under Levy noise is analyzed in depth.First,the method of generating Levy noise,the effect of tri-stable system parameters on the potential function and corresponding potential force are presented in detail.Then,the effects of tri-stable system parameters w,a,b,and Levy noise intensity amplification factor D on the resonant output can be explored with different Levy noises.Finally,the tri-stable stochastic resonance system is applied to the bearing fault detection.Simulation results show that the stochastic resonance phenomenon can be induced by tuning the system parameters w,a,and b under different distributions of Levy noise,then the weak signal can be detected.The parameter intervals which can induce stochastic resonances are approximately equal.Moreover,by adjusting the intensity amplification factor D of Levy noise,the stochastic resonances can happen similarly.In bearing fault detection,the detection effect of the tri-stable stochastic resonance system is superior to the bistable stochastic resonance system.

ATP-citrate lyase regulates stemness and metastasis in hepatocellular carcinoma via the Wnt/β-catenin signaling pathway

Background: Hepatocellular carcinoma(HCC) is one of the most highly malignant tumors. Liver tumor-initiating cells(LTICs) have been considered to contribute to HCC progression and metastasis. ATP-citrate lyase(ACLY), as a key enzyme for de novo lipogenesis, has been reported to be upregulated in various tumors. However, its expression and role in HCC and LTICs remain unknown. Methods: The expressions of ACLY in HCC tissues were detected by quantitative real-time PCR(q RT-PCR), Western blotting and immunohistochemistry. Kaplan-Meier curves and Chi-square test were used to determine the clinical significance of ACLY expression in HCC patients. A series of assays were performed to determine the function of ACLY on stemness, migration and invasion of HCC cells. Luciferase reporter assay, Western blotting and immunoprecipitation were used to study the regulation of the Wnt/β-catenin signaling by ACLY. Rescue experiments were performed to investigate whether β-catenin was the mediator of ACLY-regulated stemness and migration in HCC cells. Results: ACLY was highly expressed in HCC tissues and LTICs. Overexpression of ACLY was significantly correlated with poor prognosis, progression and metastasis of HCC patients. Knockdown of ACLY remarkably suppressed stemness properties, migration and invasion in HCC cells. Mechanistically, ACLY could regulate the canonical Wnt pathway by affecting the stability of β-catenin, and Lys49 acetylation of β-catenin might mediate ACLY-regulated β-catenin level in HCC cells. Conclusions: ACLY is a potent regulator of Wnt/β-catenin signaling in modulating LTICs stemness and metastasis in HCC. ACLY may serve as a new target for the diagnosis and treatment of HCC.

VCR-LFM-BPSK signal design for countering advanced interception technologies

The hybrid waveform of linear frequency modulation and binary phase shift keying(LFM-BPSK)can take advantages of the LFM and BPSK signals,and reduce the defects of them.However,with the development of interception technology for the LFM-BPSK signal,the application of the signal is limited.In this paper,to improve the anti-interception performance of the hybrid waveform,a new waveform of LFM-BPSK with the varying chirp rate(denoted as VCR-LFM-BPSK)is designed.In this design,based on the working principle of the interception frame for the LFM-BPSK signal,different chirp rates are introduced in different sub-pulses to prevent the signal from being intercepted by the frame.Then,to further improve the anti-interception performance of the VCR-LFM-BPSK signal,the chirp rates are optimized by minimizing the interception capability of the interceptor.Moreover,based on the VCR-LFM-BPSK signal with the optimized chirp rates,the binary phases are designed via a multiobjective Pareto optimization to improve the capabilities of autocorrelation and spectrum.Simulation results demonstrate that the designed VCR-LFM-BPSK signal outperforms the traditional LFM-BPSK signal in countering the advanced interception technologies.

Enhanced vibrational resonance in a single neuron with chemical autapse for signal detection

Many animals can detect the multi-frequency signals from their external surroundings.The understanding for underlying mechanism of signal detection can apply the theory of vibrational resonance,in which the moderate high frequency driving can maximize the nonlinear system's response to the low frequency subthreshold signal.In this work,we study the roles of chemical autapse on the vibrational resonance in a single neuron for signal detection.We reveal that the vibrational resonance is strengthened significantly by the inhibitory autapse in the neuron,while it is weakened typically by the excitatory autapse.It is generally believed that the inhibitory synapse has a suppressive effect in neuronal dynamics.However,we find that the detection of the neuron to the low frequency subthreshold signal can be improved greatly by the inhibitory autapse.Our finding indicates that the inhibitory synapse may act constructively on the detection of weak signal in the brain and neuronal system.

Target location with signal fitting and sub-aperture tracking for airborne multi-channel radar

The location of a moving target based on signal fitting and sub-aperture tracking from an airborne multi-channel radar is dealt with.The proposed approach is applied in two steps：first,the ambiguous slant-range velocity is derived with a modified single-snapshot multiple direction of arrival estimation method,and second,the unambiguous slant-range velocity is found using a track-based criterion.The prominent advantage of the proposed approach is that the unambiguous slant-range velocity can be very large.Besides,the first stage is carried out at the determinate range-Doppler test cell by azimuth searching for fitting best to the moving target signal,therefore,the location performance would not be sacrificed in order to suppress clutter and/or interference.The effectiveness and efficiency of the proposed method are validated with a set of airborne experimental data.

Cancer systems biology:signal processing for cancer research

In this editorial we introduce the research paradigms of signal processing in the era of systems biology.Signal processing is a field of science traditionally focused on modeling electronic and communications systems,but recently it has turned to biological applications with astounding results.The essence of signal processing is to describe the natural world by mathematical models and then,based on these models,develop efficient computational tools for solving engineering problems.Here,we underline,with examples,the endless possibilities which arise when the battle-hardened tools of engineering are applied to solve the problems that have tormented cancer researchers.Based on this approach,a new field has emerged,called cancer systems biology.Despite its short history,cancer systems biology has already produced several success stories tackling previously impracticable problems.Perhaps most importantly,it has been accepted as an integral part of the major endeavors of cancer research,such as analyzing the genomic and epigenomic data produced by The Cancer Genome Atlas(TCGA) project.Finally,we show that signal processing and cancer research,two fields that are seemingly distant from each other,have merged into a field that is indeed more than the sum of its parts.

Six2 is negatively correlated with prognosis and facilitates epithelial-mesenchymal transition via TGF-β/Smad signal pathway in hepatocellular carcinoma

Background: Increasing evidence indicates that Six2 contributes to tumorigenesis in various tumor in- cluding hepatocellular carcinoma (HCC). This study aimed to determine the role of Six2 in HCC and to elucidate the association of Six2 with clinical pathological characteristics. Methods: The expressions of Six2 in HCC tumor, para-tumor tissue and portal vein tumor thrombus (PVTT) were detected by tissue microarray technique, immunohistochemistry, real-time RT-PCR and West- ern blotting. Chi-square and Kaplan-Meier analysis were used to analyze the correlation between Six2 expression and prognosis of HCC patients. Lentivirus mediated Six2 knockdown, spheroid formation as- say, proliferation assay and subcutaneous tumor implantation were performed to determine the function of Six2. Results: In 274 HCC samples, Six2 was strongly expressed. Kaplan-Meier analysis revealed that high ex- pression of Six2 was correlated with a shorter overall survival (OS) and disease-free survival (DFS). More- over, Six2 expression was associated with sex, alpha-fetoprotein, tumor size and portal vein invasion. Six2 was highly expressed in PVTT. Six2 knockdown inhibited HCC cell lines proliferation, migration, and self-renewal in vitro and in vivo. In addition, low-expression of Six2 weakened TGF-β induced Smad4 activation and epithelial-mesenchymal transition in HCC cell lines. Conclusions: Elevated Six2 expression in HCC tumor patients was associated with negative prognosis. Upregulated Six2 promoted tumor growth and facilitated HCC metastasis via TGF-β/Smad signal pathway.

Biomechanical Signals Human-Computer Interface for Severe Motor Disabilities

A system that allows computer interaction by disabled people with very low mobility and who cannot use the standard procedure based on keyboard and mouse is presented. The development device uses the patient’s voluntary biomechanical signals, specifically, winks—which constitute an ability that generally remains in this kind of patients—, as interface to control the computer. A prototype based on robust and low-cost elements has been built and its performance has been validated through real trials by 16 users without previous training. The system can be optimized after a learning period in order to be adapted to every user. Also, good results were obtained in a subjective satisfaction survey that was completed by the users after carrying out the test trials.