Since the satellite communication goes in the trend of high-frequency and fast speed, the coefficients updating and the precision of the traditional pre-distortion feedback methods need to be further improved. On this...Since the satellite communication goes in the trend of high-frequency and fast speed, the coefficients updating and the precision of the traditional pre-distortion feedback methods need to be further improved. On this basis, this paper proposes dual loop feedback pre-distortion, which uses two first-order Volterra filter models to reduce the computing complexity and a dynamic error adjustment model to construct a revised feedback to ensure a better pre-distortion performance. The computation complexity, iterative convergence speed and precision of the proposed method are theoretically analyzed. Simulation results show that this dual loop feedback pre-distortion can speed the updating of coefficients and ensure the linearity of the amplifier output.展开更多
Scanning probe microscopes (SPM) are limited in their speed of data acquisition by the mechanical stability of the scanner. Therefore many types of scanners have been developed to achieve a rigid setup while maintaini...Scanning probe microscopes (SPM) are limited in their speed of data acquisition by the mechanical stability of the scanner. Therefore many types of scanners have been developed to achieve a rigid setup while maintaining an acceptable image size. We have followed here a different path to accelerate data acquisition by improving the feedback loop to achieve the same SPM image quality in a shorter time. While the feedback loop in a scanning probe microscope typically starts to probe a new pixel starting from the previous position, we have reduced the total control time by using an improved starting point for the feedback loop at each pixel. By exploiting the information of the already scanned pixels a forecast for the new pixel is created. We have successfully used several simple methods for a prognosis in MATLAB simulations like one dimensional linear or cubic extrapolation and others. Only scanning tunnelling microscope data from real experiments were used to test the forecasts. A doubling of the speed was achieved in the most favourable cases.展开更多
The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with ...The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.展开更多
Recently, self-sustained oscillatory genetic regulatory networks (GRNs) have attracted significant attention in the biological field. Given a GRN, it is important to anticipate whether the network could generate osc...Recently, self-sustained oscillatory genetic regulatory networks (GRNs) have attracted significant attention in the biological field. Given a GRN, it is important to anticipate whether the network could generate oscillation with proper parameters, and what the key ingredients for the oscillation are. In this paper the ranges of some function-related parameters which are favorable to sustained oscillations are considered. In particular, some oscillatory motifs appearing with high-frequency in most of the oscillatory GRNs are observed. Moreover, there are some anti-oscillatory motifs which have a strong oscillation repressing effect. Some conclusions analyzing these motif effects and constructing oscillatory GRNs are provided.展开更多
In this paper, we develop a new mathematical model for the mammalian circadian clock, which incorporates both transcriptional/translational feedback loops (TTFLs) and a cAMP-mediated feedback loop. The model shows t...In this paper, we develop a new mathematical model for the mammalian circadian clock, which incorporates both transcriptional/translational feedback loops (TTFLs) and a cAMP-mediated feedback loop. The model shows that TTFLs and cAMP signalling cooperatively drive the circadian rhythms. It reproduces typical experimental observations with qualitative similarities, e.g. circadian oscillations in constant darkness and entrainment to light dark cycles. In addition, it can explain the phenotypes of cAMP-mutant and Rev-erba^-/^- -mutant mice, and help us make an experimentally-testable prediction: oscillations may be rescued when arrhythmic mice with constitutively low concentrations of cAMP are crossed with Rev-erba^-/- mutant mice. The model enhances our understanding of the mammalian circadian clockwork from the viewpoint of the entire cell.展开更多
Magnetrons are widely used in microwave-based industrial applications, which are rapidly developing. However, the coupling between their output frequency and power as well as their wideband spectra restricts their fur...Magnetrons are widely used in microwave-based industrial applications, which are rapidly developing. However, the coupling between their output frequency and power as well as their wideband spectra restricts their further application. In this work, the output frequency and power of a magnetron are decoupled by self-injection. Moreover, the spectral bandwidth is narrowed, and the phase noise is reduced for most loop phase values. In order to predict the frequency variation with loop phase and injection ratio, a theoretical model based on a circuit equivalent to the magnetron is developed. Furthermore, the developed model also shows that the self-injection magnetron is stabler than the free-running magnetron and that the magnetron's phase noise can be reduced significantly for most loop phase values. Experimental results confirm the conclusions obtained using the proposed model.展开更多
Network motifs hold a very important status in genetic regulatory networks. This paper aims to analyse the dynamical property of the network motifs in genetic regulatory networks. The main result we obtained is that t...Network motifs hold a very important status in genetic regulatory networks. This paper aims to analyse the dynamical property of the network motifs in genetic regulatory networks. The main result we obtained is that the dynamical property of a single motif is very simple with only an asymptotically stable equilibrium point, but the combination of several motifs can make more complicated dynamical properties emerge such as limit cycles. The above-mentioned result shows that network motif is a stable substructure in genetic regulatory networks while their combinations make the genetic regulatory network more complicated.展开更多
This paper mainly introduces an output control method with high stable precision of a large power IGBT arc welding inverter. Experiments indicate that this kind of control mode can effectively improve the static and d...This paper mainly introduces an output control method with high stable precision of a large power IGBT arc welding inverter. Experiments indicate that this kind of control mode can effectively improve the static and dynamic characteristics and stability of power supply system. And it can decrease the spatters in the welding process apparently. This power supply is especially suitable to automatic robot welding assembly line. It will be the developing direction of robot welding supply in the future.展开更多
The oncoprotein SET is frequently overexpressed in many types of tumors and contributes to malignant initiation and progression through multiple mechanisms,including the hijacking of the tumor suppressors p53 and PP2A...The oncoprotein SET is frequently overexpressed in many types of tumors and contributes to malignant initiation and progression through multiple mechanisms,including the hijacking of the tumor suppressors p53 and PP2A.Targeting aberrant SET represents a promising strategy for cancer intervention.However,the mechanism by which endogenous SET is regulated in cancer cells remains largely unknown.Here,we identified the tumor suppressor p53 as a key regulator that transcriptionally repressed the expression of SET in both normal and cancer cells.In addition,p53 stimulated PP2A phosphatase activity via p53-mediated transcriptional repression of SET,whereby SET-mediated inhibition of PP2A was alleviated.Moreover,targeting the interaction between SET and PP2A catalytic subunit(PP2Ac)with FTY720 enhanced stress-induced p53 activation via PP2A-mediated dephosphorylation of p53 on threonine 55(Thr55).Therefore,our findings uncovered a previously unknown p53-SETPP2A regulatory feedback loop.To functionally potentiate this feedback loop,we designed a combined therapeutic strategy by simultaneously administrating a p53 activator and SET antagonist in cancer cells and observed a dramatic synergistic effect on tumor suppression.Our study reveals mechanistic insight into the regulation of the oncoprotein SET and raises a potential strategy for cancer therapy by stimulating the p53-SET-PP2A feedback loop.展开更多
Background Cancer-associated fibroblasts (CAFs) play a vital role in facilitating tumor progression through extensive reciprocal interplay with cancer cells. Tumor-derived extracellular vesicles (EVs) are the critical...Background Cancer-associated fibroblasts (CAFs) play a vital role in facilitating tumor progression through extensive reciprocal interplay with cancer cells. Tumor-derived extracellular vesicles (EVs) are the critical mediators involved in the crosstalk between cancer cells and stromal cells, contributing to the metastasis of cancers. Yet, the biological mechanisms of tumor-derived EVs in triggering CAFs phenotype to stimulate the lymph node (LN) metastasis of bladder cancer (BCa) are largely unknown. Here, we aimed to explore the effects and molecular mechanisms of tumor-derived EV-mediated CAFs phenotype in regulating BCa LN metastasis. Methods The high-throughput sequencing was utilized to identify the crucial long non-coding RNA (lncRNA) associated with CAF enrichment in BCa. The functional role of the transition of fibroblasts to CAFs induced by LINC00665-mediated EVs was investigated through the in vitro and in vivo assays. Chromatin isolation by RNA purification assays, fluorescence resonance energy transfer assays, cytokine profiling and patient-derived xenograft (PDX) model were performed to explore the underlying mechanism of LINC00665 in the LN metastasis of BCa. Results We found that CAFs are widely enriched in the tumor microenvironment of BCa, which correlated with BCa lymphangiogenesis and LN metastasis. We then identified a CAF-associated long non-coding RNA, LINC00665, which acted as a crucial mediator of CAF infiltration in BCa. Clinically, LINC00665 was associated with LN metastasis and poor prognosis in patients with BCa. Mechanistically, LINC00665 transcriptionally upregulated RAB27B expression and induced H3K4me3 modification on the promoter of RAB27B through the recruitment of hnRNPL. Moreover, RAB27B-induced EVs secretion endowed fibroblasts with the CAF phenotype, which reciprocally induced LINC00665 overexpression to form a RAB27B-HGF-c-Myc positive feedback loop, enhancing the lymphangiogenesis and LN metastasis of BCa. Importantly, we demonstrated that blocking EV-transmitted LINC00665 or HGF broke this loop and impaired BCa lymphangiogenesis in a PDX model. Conclusion Our study uncovers a precise mechanism that LINC00665 sustains BCa LN metastasis by inducing a RAB27B-HGF-c-Myc positive feedback loop between BCa cells and fibroblasts, suggesting that LINC00665 could be a promising therapeutic target for patients with LN metastatic BCa.展开更多
In the face of the elevated incidence and mortality rate of septic shock in the ICU,this retrospective study seeks to investigate the indicative and predictive value of high-mobility group box 1(HMGB1)and miR-146b in ...In the face of the elevated incidence and mortality rate of septic shock in the ICU,this retrospective study seeks to investigate the indicative and predictive value of high-mobility group box 1(HMGB1)and miR-146b in patients with septic shock.Quantitative RTPCR was employed in this study to quantify the HMGB1 and miR-146b levels in plasma samples obtained from the patient group and healthy controls.The investigation involved the comparison between the two groups and tracking changes in the patient group over time.The finding revealed that upon admission,the patient group exhibited markedly elevated relative expression levels of HMGB1,which subsequently decreased over time.Conversely,the patient group displayed significantly reduced relative expression levels of miR-146b upon admission,which subsequently increased over time compared to the control group.Receiver operating characteristic(ROC)curves showed good predictive value for HMGB1 and miR-146b.The experimental results suggest that HMGB1 and miR-146b serve as valuable and convenient biomarkers for evaluating the severity of septic shock and predicting mortality.Additionally,it is proposed that serum miR-146b may be inducible and potentially exerts a negative regulatory effect on the expression of HMGB1.展开更多
Cervical cancer(CC)is recognized as the most common neoplasm in the female reproductive system worldwide.The lack of chemotherapeutic agents with outstanding effectiveness and safety severely compromises the anti-cipa...Cervical cancer(CC)is recognized as the most common neoplasm in the female reproductive system worldwide.The lack of chemotherapeutic agents with outstanding effectiveness and safety severely compromises the anti-cipated prognosis of patients.Aloperine(ALO)is a natural quinolizidine alkaloid with marked anti-cancer effects on multiple malignancies as well as favorable activity in relieving inflammation,allergies and infection.However,its therapeutic efficacy and underlying mechanism in CC are still unclear.In the current study,MTT assay was employed to evaluate the viability of HeLa cells exposed to ALO to preliminarily estimate the effectiveness of ALO in CC.Then,the effects of ALO on the proliferation and apoptosis of HeLa cells were further investigated by plate colony formation and flow cytometry,respectively,while the migration and invasion of ALO-treated HeLa cells were evaluated using Transwell assay.Moreover,nude mice were subcutaneously inoculated with HeLa cells to demonstrate the anti-CC properties of ALO in vivo.The molecular mechanisms underlying these effects of ALO were evaluated by Western blot and immunohistochemical analysis.This study experimentally demonstrated that ALO inhibited the proliferation of HeLa cells via G2 phase cell cycle arrest.Simultaneously,ALO promoted an increase in the percentage of apoptotic HeLa cells by increasing the Bax/Bcl-2 ratio.Additionally,the migration and invasion of HeLa cells were attenuated by ALO treatment,which was considered to result from inhibition of epithelial-to-mesenchymal transition.For molecular mechanisms,the expression and activation of the IL-6-JAK1-STAT3 feedback loop were markedly suppressed by ALO treatment.This study indicated that ALO markedly suppresses the proliferation,migration and invasion and enhances the apoptosis of HeLa cells.In addition,these prominent anti-CC properties of ALO are associated with repression of the IL-6-JAK1-STAT3 feedback loop.展开更多
Background:Considering the increase in the proportion of lung adenocarcinoma(LUAD)cases among all lung cancers and its considerable contribution to cancer-related deaths worldwide,we sought to identify novel oncogenes...Background:Considering the increase in the proportion of lung adenocarcinoma(LUAD)cases among all lung cancers and its considerable contribution to cancer-related deaths worldwide,we sought to identify novel oncogenes to provide potential targets and facilitate a better understanding of the malignant progression of LUAD.Methods:The results from the screening of transcriptome and survival analyses according to the integrated Gene Expression Omnibus(GEO)datasets and The Cancer Genome Atlas(TCGA)data were combined,and a promising risk biomarker called meiotic nuclear divisions 1(MND1)was selectively acquired.Cell viability assays and subcutaneous xenograftmodelswere used to validate the oncogenic role ofMND1 in LUADcell proliferation and tumor growth.Aseries of assays,including mass spectrometry,co-immunoprecipitation(Co-IP),and chromatin immunoprecipitation(ChIP),were performed to explore the underlying mechanism.Results:MND1 up-regulation was identified to be an independent risk factor for overall survival in LUAD patients evaluated by both tissue microarray staining and third party data analysis.In vivo and in vitro assays showed that MND1 promoted LUAD cell proliferation by regulating cell cycle.The results of the Co-IP,ChIP and dual-luciferase reporter assays validated that MND1 competitively bound to tumor suppressor Kruppel-like factor 6(KLF6),and thereby protecting E2F transcription factor 1(E2F1)from KLF6-induced transcriptional repression.Luciferase reporter and ChIP assays found that E2F1 activated MND1 transcription by binding to its promoter in a feedback manner.Conclusions:MND1,KLF6,and E2F1 form a positive feedback loop to regulate cell cycle and confer DDP resistance in LUAD.MND1 is crucial for malignant progression and may be a potential therapeutic target in LUAD patients.展开更多
Background:Head and neck squamous cell carcinoma(HNSCC)is one of the most frequent malignancies worldwide and is characterized by unfavorable prognosis,high lymph node metastasis and early recurrence.However,the mole...Background:Head and neck squamous cell carcinoma(HNSCC)is one of the most frequent malignancies worldwide and is characterized by unfavorable prognosis,high lymph node metastasis and early recurrence.However,the molecular events regulating HNSCC tumorigenesis remain poorly understood.Therefore,uncovering the underlying mechanisms is urgently needed to identify novel and promising therapeutic targets for HNSCC.In this study,we aimed to explore the role of pleckstrin-2(PLEK2)in regulating HNSCC tumorigenesis.Methods:The expression pattern of PLEK2 and its clinical significance in HNSCC were determined by analyzing publicly assessable datasets and our own independent HNSCC cohort.In vitro and in vivo experiments,including cell proliferation,colony formation,Matrigel invasion,tumor sphere formation,ALDEFLUOR,Western blotting assays and xenograft mouse models,were used to investigate the role of PLEK2 in regulating the malignant behaviors of HNSCC cells.The underlying molecular mechanisms for the tumor-promoting role of PLEK2 were elucidated using co-immunoprecipitation,cycloheximide chase analysis,ubiquitination assays,chromatin immunoprecipitation-quantitative polymerase chain reaction,luciferase reporter assays and rescue experiments.Results:The expression levels of PLEK2 mRNA and protein were significantly increased in HNSCC tissues,and PLEK2 overexpression was strongly associated with poor overall survival and therapeutic resistance.Additionally,PLEK2 was important for maintaining the proliferation,invasion,epithelial-mesenchymal transition,cancer stemness and tumorigenesis of HNSCC cells and could alter the cellular metabolism of the cancer cells.Mechanistically,PLEK2 interacted with c-Myc and reduced the association of F-box and WD repeat domain containing 7(FBXW7)with c-Myc,thereby avoiding ubiquitination and subsequent proteasome-mediated degradation of c-Myc.Moreover,the c-Myc signaling activated by PLEK2 was important for sustaining the aggressive malignant phenotypes and tumorigenesis of HNSCC cells.c-Myc also directly bounded to the PLEK2 promoter and activated its transcription,forming a positive feedback loop.Conclusions:Collectively,these findings uncover a previously unknown molecular basis of PLEK2-enhanced c-Myc signaling in HNSCC,suggesting that PLEK2 may represent a promising therapeutic target for treating HNSCC.展开更多
We propose an all-optical WDM buffer for optical packet switching system, which consists of NOLM and feedback loop. The proposed structure provides more than 40 turn buffering and nice output of buffered data when sel...We propose an all-optical WDM buffer for optical packet switching system, which consists of NOLM and feedback loop. The proposed structure provides more than 40 turn buffering and nice output of buffered data when selected by control signal.展开更多
Trichomes are universally present in plants and their development is delicately regulated.Trichomes are responsible for pubescence,whose density is associated with some agronomic traits such as insect resis-tance,evap...Trichomes are universally present in plants and their development is delicately regulated.Trichomes are responsible for pubescence,whose density is associated with some agronomic traits such as insect resis-tance,evapotranspiration,and yield.Almost a century ago,three dominant alleles related to pubescence density in soybean,namely Pd1(dense pubescence),Ps(sparse pubescence),and P1(glabrous),were iden-tified.However,their molecular identity and genetic relationships remain unclear.In this study,through a genome-wide association study and map-based cloning,we determined the genetic basis of these three traits.The sparse-pubescence phenotype of Ps was attributed to a copy-number variation of a 25.6-kb sequence that includes a gene encoding a protein with WD40 and RING domains.The dense-pubescence phenotype of Pd1 was attributed to a T-C transition in the last exon of an HD-Zip transcription factor gene,and the glabrous phenotype of P1 was caused by a G-A transition in the first exon of a lipid transfer protein gene.Genetic and biochemical analyses revealed that Pd1 functions as a transcriptional activator that can bind the promoters of the P1 and Ps genes to induce their expression;Interestingly,Pd1 can also bind its own promoter and inhibit its gene transcription.In addition,Ps can interact with Pd1 and weaken the tran-scriptional activity of Pd1.Taken together,our results demonstrate that Pd1,Ps,and P1 form a complex feedback loop to regulate pubescence formation in soybean.展开更多
The next generation of high-power lasers enables repetition of experiments at orders of magnitude higher frequency than what was possible using the prior generation.Facilities requiring human intervention between lase...The next generation of high-power lasers enables repetition of experiments at orders of magnitude higher frequency than what was possible using the prior generation.Facilities requiring human intervention between laser repetitions need to adapt in order to keep pace with the new laser technology.A distributed networked control system can enable laboratory-wide automation and feedback control loops.These higher-repetition-rate experiments will create enormous quantities of data.A consistent approach to managing data can increase data accessibility,reduce repetitive data-software development and mitigate poorly organized metadata.An opportunity arises to share knowledge of improvements to control and data infrastructure currently being undertaken.We compare platforms and approaches to state-of-the-art control systems and data management at high-power laser facilities,and we illustrate these topics with case studies from our community.展开更多
Aims:This review was developed to introduce the essential components and variants of structural equation modeling(SEM),synthesize the common issues in SEM applications,and share our views on SEM’s future in ecologica...Aims:This review was developed to introduce the essential components and variants of structural equation modeling(SEM),synthesize the common issues in SEM applications,and share our views on SEM’s future in ecological research.Methods:We searched the Web of Science on SEM applications in ecological studies from 1999 through 2016 and summarized the potential of SEMs,with a special focus on unexplored uses in ecology.We also analyzed and discussed the common issues with SEM applications in previous publications and presented our view for its future applications.Results:We searched and found 146 relevant publications on SEM applications in ecological studies.We found that five SEM variants had not commenly been applied in ecology,including the latent growth curve model,Bayesian SEM,partial least square SEM,hierarchical SEM,and variable/model selection.We identified ten common issues in SEM applications including strength of causal assumption,specification of feedback loops,selection of models and variables,identification of models,methods of estimation,explanation of latent variables,selection of fit indices,report of results,estimation of sample size,and the fit of model.Conclusions:In previous ecological studies,measurements of latent variables,explanations of model parameters,and reports of key statistics were commonly overlooked,while several advanced uses of SEM had been ignored overall.With the increasing availability of data,the use of SEM holds immense potential for ecologists in the future.展开更多
A revised concept for urban water metabolism (UWM) is presented in this study to address the inadequacies in current research on UWM and the problems associated with the traditional urban water metabolic process. Fe...A revised concept for urban water metabolism (UWM) is presented in this study to address the inadequacies in current research on UWM and the problems associated with the traditional urban water metabolic process. Feedback loops can be analyzed to increase the water environmental carrying capacity (WECC) of the new urban water metabolism system (UWMS) over that of a traditional UWMS. An analysis of the feedback loops of an UWMS was used to construct a system dynamics (SD) model for the system under a WECC restriction. Water metabolic processes were simulated for different scenarios using the Tongzhou District in Beijing as an example. The results for the newly developed UWM case showed that a water environment of Tongzhou District could support a population of 1.1926 × 106, an irrigation area of 375.521 km2, a livestock of 0.7732 × 106, and an industrial value added of ¥193.14 × 109 (i.e. about US$28.285 × 109) in 2020. A sensitivity analysis showed that the WECC could be improved to some extent by constructing new sewage treatment facilities or by expanding the current sewage treatment facilities, using reclaimed water and improving the water circulation system.展开更多
The circadian clock temporally coordinates plant growth and metabolism in close synchronization with the diurnal and seasonal environmental changes. Research over the last decade has identified a number of clock compo...The circadian clock temporally coordinates plant growth and metabolism in close synchronization with the diurnal and seasonal environmental changes. Research over the last decade has identified a number of clock components and a variety of regulatory mechanisms responsible for the rhythmic oscillations in metabolic and physiological activities. At the core of the clock, transcriptional/translational feedback loops modulate the expression of a significant proportion of the genome. In this article, we briefly describe some of the very recent advances that have improved our understanding of clock organization and function in Arabidopsis thaliana. The new studies illustrate the role of clock protein complex for- mation on circadian gating of plant growth and identify alternative splicing as a new regulatory mechanism for clock function. Examination of key clock properties such as temperature compensation has also opened new avenues for func- tional research within the plant clockwork. The emerging connections between the circadian clock and metabolism, hor- mone signaling and response to biotic and abiotic stress also add new layers of complexity to the clock network and underscore the significance of the circadian clock regulating the daily life of plants.展开更多
文摘Since the satellite communication goes in the trend of high-frequency and fast speed, the coefficients updating and the precision of the traditional pre-distortion feedback methods need to be further improved. On this basis, this paper proposes dual loop feedback pre-distortion, which uses two first-order Volterra filter models to reduce the computing complexity and a dynamic error adjustment model to construct a revised feedback to ensure a better pre-distortion performance. The computation complexity, iterative convergence speed and precision of the proposed method are theoretically analyzed. Simulation results show that this dual loop feedback pre-distortion can speed the updating of coefficients and ensure the linearity of the amplifier output.
文摘Scanning probe microscopes (SPM) are limited in their speed of data acquisition by the mechanical stability of the scanner. Therefore many types of scanners have been developed to achieve a rigid setup while maintaining an acceptable image size. We have followed here a different path to accelerate data acquisition by improving the feedback loop to achieve the same SPM image quality in a shorter time. While the feedback loop in a scanning probe microscope typically starts to probe a new pixel starting from the previous position, we have reduced the total control time by using an improved starting point for the feedback loop at each pixel. By exploiting the information of the already scanned pixels a forecast for the new pixel is created. We have successfully used several simple methods for a prognosis in MATLAB simulations like one dimensional linear or cubic extrapolation and others. Only scanning tunnelling microscope data from real experiments were used to test the forecasts. A doubling of the speed was achieved in the most favourable cases.
文摘The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10975015)the National Basic Research Program of China (Grant No. 2007CB814800)
文摘Recently, self-sustained oscillatory genetic regulatory networks (GRNs) have attracted significant attention in the biological field. Given a GRN, it is important to anticipate whether the network could generate oscillation with proper parameters, and what the key ingredients for the oscillation are. In this paper the ranges of some function-related parameters which are favorable to sustained oscillations are considered. In particular, some oscillatory motifs appearing with high-frequency in most of the oscillatory GRNs are observed. Moreover, there are some anti-oscillatory motifs which have a strong oscillation repressing effect. Some conclusions analyzing these motif effects and constructing oscillatory GRNs are provided.
基金Project supported by the State Key Program of National Natural Science Foundation of China (Grant No 60736028)the National Natural Science Foundation of China (Grant Nos 10871074 and 60704045)the Research Fund for the Doctoral Program of Higher Education of China (Grant No 20070558053)
文摘In this paper, we develop a new mathematical model for the mammalian circadian clock, which incorporates both transcriptional/translational feedback loops (TTFLs) and a cAMP-mediated feedback loop. The model shows that TTFLs and cAMP signalling cooperatively drive the circadian rhythms. It reproduces typical experimental observations with qualitative similarities, e.g. circadian oscillations in constant darkness and entrainment to light dark cycles. In addition, it can explain the phenotypes of cAMP-mutant and Rev-erba^-/^- -mutant mice, and help us make an experimentally-testable prediction: oscillations may be rescued when arrhythmic mice with constitutively low concentrations of cAMP are crossed with Rev-erba^-/- mutant mice. The model enhances our understanding of the mammalian circadian clockwork from the viewpoint of the entire cell.
基金supported by the National Basic Research Program of China(Grant No.2013CB328902)the National Natural Science Foundation of China(Grant No.61501311)
文摘Magnetrons are widely used in microwave-based industrial applications, which are rapidly developing. However, the coupling between their output frequency and power as well as their wideband spectra restricts their further application. In this work, the output frequency and power of a magnetron are decoupled by self-injection. Moreover, the spectral bandwidth is narrowed, and the phase noise is reduced for most loop phase values. In order to predict the frequency variation with loop phase and injection ratio, a theoretical model based on a circuit equivalent to the magnetron is developed. Furthermore, the developed model also shows that the self-injection magnetron is stabler than the free-running magnetron and that the magnetron's phase noise can be reduced significantly for most loop phase values. Experimental results confirm the conclusions obtained using the proposed model.
基金Project supported by the National Natural Science Foundation of China (Grant No 10672093) and Innovation Foundation of , Shanghai University for Postgraduates, China.
文摘Network motifs hold a very important status in genetic regulatory networks. This paper aims to analyse the dynamical property of the network motifs in genetic regulatory networks. The main result we obtained is that the dynamical property of a single motif is very simple with only an asymptotically stable equilibrium point, but the combination of several motifs can make more complicated dynamical properties emerge such as limit cycles. The above-mentioned result shows that network motif is a stable substructure in genetic regulatory networks while their combinations make the genetic regulatory network more complicated.
文摘This paper mainly introduces an output control method with high stable precision of a large power IGBT arc welding inverter. Experiments indicate that this kind of control mode can effectively improve the static and dynamic characteristics and stability of power supply system. And it can decrease the spatters in the welding process apparently. This power supply is especially suitable to automatic robot welding assembly line. It will be the developing direction of robot welding supply in the future.
基金supported by Beijing Municipal Natural Science Foundation(7192126)the National Natural Science Foundation of China(81872311,82073132,82122054,and 81720108027)+1 种基金the National Key R&D Program of China(2019YFC1005200,and 2019YFC1005201)CAMS Innovation Fund for Medical Sciences(2021-I2M-1-016)。
文摘The oncoprotein SET is frequently overexpressed in many types of tumors and contributes to malignant initiation and progression through multiple mechanisms,including the hijacking of the tumor suppressors p53 and PP2A.Targeting aberrant SET represents a promising strategy for cancer intervention.However,the mechanism by which endogenous SET is regulated in cancer cells remains largely unknown.Here,we identified the tumor suppressor p53 as a key regulator that transcriptionally repressed the expression of SET in both normal and cancer cells.In addition,p53 stimulated PP2A phosphatase activity via p53-mediated transcriptional repression of SET,whereby SET-mediated inhibition of PP2A was alleviated.Moreover,targeting the interaction between SET and PP2A catalytic subunit(PP2Ac)with FTY720 enhanced stress-induced p53 activation via PP2A-mediated dephosphorylation of p53 on threonine 55(Thr55).Therefore,our findings uncovered a previously unknown p53-SETPP2A regulatory feedback loop.To functionally potentiate this feedback loop,we designed a combined therapeutic strategy by simultaneously administrating a p53 activator and SET antagonist in cancer cells and observed a dramatic synergistic effect on tumor suppression.Our study reveals mechanistic insight into the regulation of the oncoprotein SET and raises a potential strategy for cancer therapy by stimulating the p53-SET-PP2A feedback loop.
基金funded by the National Key Research and Development Program of China(Grant No.2022YFA1305500 and 2018YFA0902803)the National Natural Science Foundation of China(Grant No.82173272,82173271,81825016,82103536,82103416,81871945 and 81902589)+1 种基金Guangdong Basic and Applied Basic Research Foundation(Grant No.2021B1515020091,2020A1515010815,2018B010109006,and 2021A1515010355)the Science and Technology Program of Guangzhou,China(Grant No.202002030388,201803010049,and 2017B020227007).
文摘Background Cancer-associated fibroblasts (CAFs) play a vital role in facilitating tumor progression through extensive reciprocal interplay with cancer cells. Tumor-derived extracellular vesicles (EVs) are the critical mediators involved in the crosstalk between cancer cells and stromal cells, contributing to the metastasis of cancers. Yet, the biological mechanisms of tumor-derived EVs in triggering CAFs phenotype to stimulate the lymph node (LN) metastasis of bladder cancer (BCa) are largely unknown. Here, we aimed to explore the effects and molecular mechanisms of tumor-derived EV-mediated CAFs phenotype in regulating BCa LN metastasis. Methods The high-throughput sequencing was utilized to identify the crucial long non-coding RNA (lncRNA) associated with CAF enrichment in BCa. The functional role of the transition of fibroblasts to CAFs induced by LINC00665-mediated EVs was investigated through the in vitro and in vivo assays. Chromatin isolation by RNA purification assays, fluorescence resonance energy transfer assays, cytokine profiling and patient-derived xenograft (PDX) model were performed to explore the underlying mechanism of LINC00665 in the LN metastasis of BCa. Results We found that CAFs are widely enriched in the tumor microenvironment of BCa, which correlated with BCa lymphangiogenesis and LN metastasis. We then identified a CAF-associated long non-coding RNA, LINC00665, which acted as a crucial mediator of CAF infiltration in BCa. Clinically, LINC00665 was associated with LN metastasis and poor prognosis in patients with BCa. Mechanistically, LINC00665 transcriptionally upregulated RAB27B expression and induced H3K4me3 modification on the promoter of RAB27B through the recruitment of hnRNPL. Moreover, RAB27B-induced EVs secretion endowed fibroblasts with the CAF phenotype, which reciprocally induced LINC00665 overexpression to form a RAB27B-HGF-c-Myc positive feedback loop, enhancing the lymphangiogenesis and LN metastasis of BCa. Importantly, we demonstrated that blocking EV-transmitted LINC00665 or HGF broke this loop and impaired BCa lymphangiogenesis in a PDX model. Conclusion Our study uncovers a precise mechanism that LINC00665 sustains BCa LN metastasis by inducing a RAB27B-HGF-c-Myc positive feedback loop between BCa cells and fibroblasts, suggesting that LINC00665 could be a promising therapeutic target for patients with LN metastatic BCa.
基金Supported by the Natural Science Foundation of Hubei Province(2021CFB026)Scientific Research Project of Hubei Pathophysiological Society(2021HBAP002)+2 种基金Medical Service Capacity Building and Health Personnel Training Project of the Central Government(New Finance Society[2022]No.255)Key Project of Science and Technology Program of Nanshan District,Shenzhen(NS2022014)Wu Jieping Medical Foundation Clinical Research Project(320.6750.2021-11-12)。
文摘In the face of the elevated incidence and mortality rate of septic shock in the ICU,this retrospective study seeks to investigate the indicative and predictive value of high-mobility group box 1(HMGB1)and miR-146b in patients with septic shock.Quantitative RTPCR was employed in this study to quantify the HMGB1 and miR-146b levels in plasma samples obtained from the patient group and healthy controls.The investigation involved the comparison between the two groups and tracking changes in the patient group over time.The finding revealed that upon admission,the patient group exhibited markedly elevated relative expression levels of HMGB1,which subsequently decreased over time.Conversely,the patient group displayed significantly reduced relative expression levels of miR-146b upon admission,which subsequently increased over time compared to the control group.Receiver operating characteristic(ROC)curves showed good predictive value for HMGB1 and miR-146b.The experimental results suggest that HMGB1 and miR-146b serve as valuable and convenient biomarkers for evaluating the severity of septic shock and predicting mortality.Additionally,it is proposed that serum miR-146b may be inducible and potentially exerts a negative regulatory effect on the expression of HMGB1.
基金This work was supported by the National Natural Science Foundation of China(No.82001850)Shanxi Basic Application Research(No.201901D211491)+2 种基金the Scientific Research Project of Shanxi Health Commission(No.2019038)the Doctoral Research Project of Shanxi Medical University(No.XD1901)the Doctoral Research Project of Shanxi Province(No.SD1901).
文摘Cervical cancer(CC)is recognized as the most common neoplasm in the female reproductive system worldwide.The lack of chemotherapeutic agents with outstanding effectiveness and safety severely compromises the anti-cipated prognosis of patients.Aloperine(ALO)is a natural quinolizidine alkaloid with marked anti-cancer effects on multiple malignancies as well as favorable activity in relieving inflammation,allergies and infection.However,its therapeutic efficacy and underlying mechanism in CC are still unclear.In the current study,MTT assay was employed to evaluate the viability of HeLa cells exposed to ALO to preliminarily estimate the effectiveness of ALO in CC.Then,the effects of ALO on the proliferation and apoptosis of HeLa cells were further investigated by plate colony formation and flow cytometry,respectively,while the migration and invasion of ALO-treated HeLa cells were evaluated using Transwell assay.Moreover,nude mice were subcutaneously inoculated with HeLa cells to demonstrate the anti-CC properties of ALO in vivo.The molecular mechanisms underlying these effects of ALO were evaluated by Western blot and immunohistochemical analysis.This study experimentally demonstrated that ALO inhibited the proliferation of HeLa cells via G2 phase cell cycle arrest.Simultaneously,ALO promoted an increase in the percentage of apoptotic HeLa cells by increasing the Bax/Bcl-2 ratio.Additionally,the migration and invasion of HeLa cells were attenuated by ALO treatment,which was considered to result from inhibition of epithelial-to-mesenchymal transition.For molecular mechanisms,the expression and activation of the IL-6-JAK1-STAT3 feedback loop were markedly suppressed by ALO treatment.This study indicated that ALO markedly suppresses the proliferation,migration and invasion and enhances the apoptosis of HeLa cells.In addition,these prominent anti-CC properties of ALO are associated with repression of the IL-6-JAK1-STAT3 feedback loop.
基金Project of Jiangsu Provincial Medical Talent,Grant/Award Number:ZDRCA2016033China Postdoctoral Science Foundation,Grant/Award Number:2018M640465+2 种基金National Natural Science Foundation of China,Grant/Award Numbers:81672295,81702265,81802277,81872378Research Program of Jiangsu Health Department,Grant/Award Number:LGY2016025Social Development Project of Jiangsu Province,Grant/Award Number:BE2019758。
文摘Background:Considering the increase in the proportion of lung adenocarcinoma(LUAD)cases among all lung cancers and its considerable contribution to cancer-related deaths worldwide,we sought to identify novel oncogenes to provide potential targets and facilitate a better understanding of the malignant progression of LUAD.Methods:The results from the screening of transcriptome and survival analyses according to the integrated Gene Expression Omnibus(GEO)datasets and The Cancer Genome Atlas(TCGA)data were combined,and a promising risk biomarker called meiotic nuclear divisions 1(MND1)was selectively acquired.Cell viability assays and subcutaneous xenograftmodelswere used to validate the oncogenic role ofMND1 in LUADcell proliferation and tumor growth.Aseries of assays,including mass spectrometry,co-immunoprecipitation(Co-IP),and chromatin immunoprecipitation(ChIP),were performed to explore the underlying mechanism.Results:MND1 up-regulation was identified to be an independent risk factor for overall survival in LUAD patients evaluated by both tissue microarray staining and third party data analysis.In vivo and in vitro assays showed that MND1 promoted LUAD cell proliferation by regulating cell cycle.The results of the Co-IP,ChIP and dual-luciferase reporter assays validated that MND1 competitively bound to tumor suppressor Kruppel-like factor 6(KLF6),and thereby protecting E2F transcription factor 1(E2F1)from KLF6-induced transcriptional repression.Luciferase reporter and ChIP assays found that E2F1 activated MND1 transcription by binding to its promoter in a feedback manner.Conclusions:MND1,KLF6,and E2F1 form a positive feedback loop to regulate cell cycle and confer DDP resistance in LUAD.MND1 is crucial for malignant progression and may be a potential therapeutic target in LUAD patients.
基金National Natural Science Foundation of China,Grant/Award Number:81901006Guangdong Basic and Applied Basic Research Foundation,Grant/Award Number:2020A1515110051+1 种基金Scientific Research Talent Cultivation Project of Stomatological Hospital,Southern Medical University,Grant/Award Number:RC202005Science Research Cultivation Program of Stomatological Hospital,Southern Medical University,Grant/Award Number:PY2020002。
文摘Background:Head and neck squamous cell carcinoma(HNSCC)is one of the most frequent malignancies worldwide and is characterized by unfavorable prognosis,high lymph node metastasis and early recurrence.However,the molecular events regulating HNSCC tumorigenesis remain poorly understood.Therefore,uncovering the underlying mechanisms is urgently needed to identify novel and promising therapeutic targets for HNSCC.In this study,we aimed to explore the role of pleckstrin-2(PLEK2)in regulating HNSCC tumorigenesis.Methods:The expression pattern of PLEK2 and its clinical significance in HNSCC were determined by analyzing publicly assessable datasets and our own independent HNSCC cohort.In vitro and in vivo experiments,including cell proliferation,colony formation,Matrigel invasion,tumor sphere formation,ALDEFLUOR,Western blotting assays and xenograft mouse models,were used to investigate the role of PLEK2 in regulating the malignant behaviors of HNSCC cells.The underlying molecular mechanisms for the tumor-promoting role of PLEK2 were elucidated using co-immunoprecipitation,cycloheximide chase analysis,ubiquitination assays,chromatin immunoprecipitation-quantitative polymerase chain reaction,luciferase reporter assays and rescue experiments.Results:The expression levels of PLEK2 mRNA and protein were significantly increased in HNSCC tissues,and PLEK2 overexpression was strongly associated with poor overall survival and therapeutic resistance.Additionally,PLEK2 was important for maintaining the proliferation,invasion,epithelial-mesenchymal transition,cancer stemness and tumorigenesis of HNSCC cells and could alter the cellular metabolism of the cancer cells.Mechanistically,PLEK2 interacted with c-Myc and reduced the association of F-box and WD repeat domain containing 7(FBXW7)with c-Myc,thereby avoiding ubiquitination and subsequent proteasome-mediated degradation of c-Myc.Moreover,the c-Myc signaling activated by PLEK2 was important for sustaining the aggressive malignant phenotypes and tumorigenesis of HNSCC cells.c-Myc also directly bounded to the PLEK2 promoter and activated its transcription,forming a positive feedback loop.Conclusions:Collectively,these findings uncover a previously unknown molecular basis of PLEK2-enhanced c-Myc signaling in HNSCC,suggesting that PLEK2 may represent a promising therapeutic target for treating HNSCC.
文摘We propose an all-optical WDM buffer for optical packet switching system, which consists of NOLM and feedback loop. The proposed structure provides more than 40 turn buffering and nice output of buffered data when selected by control signal.
基金the National Key Research and Development Program(2016YFD0100401)the Ministry of Agriculture of the People's Republic of China(2016ZX08009003)the National Natural Science Foundation of China(grant nos.32001501,31788103,and 31525018).
文摘Trichomes are universally present in plants and their development is delicately regulated.Trichomes are responsible for pubescence,whose density is associated with some agronomic traits such as insect resis-tance,evapotranspiration,and yield.Almost a century ago,three dominant alleles related to pubescence density in soybean,namely Pd1(dense pubescence),Ps(sparse pubescence),and P1(glabrous),were iden-tified.However,their molecular identity and genetic relationships remain unclear.In this study,through a genome-wide association study and map-based cloning,we determined the genetic basis of these three traits.The sparse-pubescence phenotype of Ps was attributed to a copy-number variation of a 25.6-kb sequence that includes a gene encoding a protein with WD40 and RING domains.The dense-pubescence phenotype of Pd1 was attributed to a T-C transition in the last exon of an HD-Zip transcription factor gene,and the glabrous phenotype of P1 was caused by a G-A transition in the first exon of a lipid transfer protein gene.Genetic and biochemical analyses revealed that Pd1 functions as a transcriptional activator that can bind the promoters of the P1 and Ps genes to induce their expression;Interestingly,Pd1 can also bind its own promoter and inhibit its gene transcription.In addition,Ps can interact with Pd1 and weaken the tran-scriptional activity of Pd1.Taken together,our results demonstrate that Pd1,Ps,and P1 form a complex feedback loop to regulate pubescence formation in soybean.
基金A.J.acknowledges the support from DOE Grant#DESC0016804.
文摘The next generation of high-power lasers enables repetition of experiments at orders of magnitude higher frequency than what was possible using the prior generation.Facilities requiring human intervention between laser repetitions need to adapt in order to keep pace with the new laser technology.A distributed networked control system can enable laboratory-wide automation and feedback control loops.These higher-repetition-rate experiments will create enormous quantities of data.A consistent approach to managing data can increase data accessibility,reduce repetitive data-software development and mitigate poorly organized metadata.An opportunity arises to share knowledge of improvements to control and data infrastructure currently being undertaken.We compare platforms and approaches to state-of-the-art control systems and data management at high-power laser facilities,and we illustrate these topics with case studies from our community.
基金supported by the Sustainable Energy Pathways(CHE)Program(#1230246)the Dynamics of Coupled Natural and Human Systems(CNH)Program(#1313761)of the US National Science Foundation(NSF)。
文摘Aims:This review was developed to introduce the essential components and variants of structural equation modeling(SEM),synthesize the common issues in SEM applications,and share our views on SEM’s future in ecological research.Methods:We searched the Web of Science on SEM applications in ecological studies from 1999 through 2016 and summarized the potential of SEMs,with a special focus on unexplored uses in ecology.We also analyzed and discussed the common issues with SEM applications in previous publications and presented our view for its future applications.Results:We searched and found 146 relevant publications on SEM applications in ecological studies.We found that five SEM variants had not commenly been applied in ecology,including the latent growth curve model,Bayesian SEM,partial least square SEM,hierarchical SEM,and variable/model selection.We identified ten common issues in SEM applications including strength of causal assumption,specification of feedback loops,selection of models and variables,identification of models,methods of estimation,explanation of latent variables,selection of fit indices,report of results,estimation of sample size,and the fit of model.Conclusions:In previous ecological studies,measurements of latent variables,explanations of model parameters,and reports of key statistics were commonly overlooked,while several advanced uses of SEM had been ignored overall.With the increasing availability of data,the use of SEM holds immense potential for ecologists in the future.
文摘A revised concept for urban water metabolism (UWM) is presented in this study to address the inadequacies in current research on UWM and the problems associated with the traditional urban water metabolic process. Feedback loops can be analyzed to increase the water environmental carrying capacity (WECC) of the new urban water metabolism system (UWMS) over that of a traditional UWMS. An analysis of the feedback loops of an UWMS was used to construct a system dynamics (SD) model for the system under a WECC restriction. Water metabolic processes were simulated for different scenarios using the Tongzhou District in Beijing as an example. The results for the newly developed UWM case showed that a water environment of Tongzhou District could support a population of 1.1926 × 106, an irrigation area of 375.521 km2, a livestock of 0.7732 × 106, and an industrial value added of ¥193.14 × 109 (i.e. about US$28.285 × 109) in 2020. A sensitivity analysis showed that the WECC could be improved to some extent by constructing new sewage treatment facilities or by expanding the current sewage treatment facilities, using reclaimed water and improving the water circulation system.
文摘The circadian clock temporally coordinates plant growth and metabolism in close synchronization with the diurnal and seasonal environmental changes. Research over the last decade has identified a number of clock components and a variety of regulatory mechanisms responsible for the rhythmic oscillations in metabolic and physiological activities. At the core of the clock, transcriptional/translational feedback loops modulate the expression of a significant proportion of the genome. In this article, we briefly describe some of the very recent advances that have improved our understanding of clock organization and function in Arabidopsis thaliana. The new studies illustrate the role of clock protein complex for- mation on circadian gating of plant growth and identify alternative splicing as a new regulatory mechanism for clock function. Examination of key clock properties such as temperature compensation has also opened new avenues for func- tional research within the plant clockwork. The emerging connections between the circadian clock and metabolism, hor- mone signaling and response to biotic and abiotic stress also add new layers of complexity to the clock network and underscore the significance of the circadian clock regulating the daily life of plants.