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Sanjie Zhentong capsules were scanned by using a near infrared spectra probe with different drug mass fraction and the spectral information of capsule shells and contents in it were obtained. Then partial least squares (PLS) models were developed for the prediction of mass fraction of Fritillariae Thunbergii Bulbus and Resine draconis in Sanjie Zhentong capsules. The correlation coefficient (r9c)) and root mean standard error( RMSEC) of 0.949 5, 0.958 2 and 4.742 4, 4.135 7. The models obtained correlation coefficient (r(v)) of 0.919 2, 0.936 7 and root mean square error (RMSECV) of 6.158 9, 5.037 3 respectively in the training set. The paired T test analysis of statistics showed that there were no significant difference between predictive values and measure values. The established models reflected a strong prediction performance and can meet the needs of the production.
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Medicamentos de Ervas Chinesas/química , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Cápsulas/química , Análise dos Mínimos QuadradosRESUMO
The control of planetary rovers, which are high performance mobile robots that move on deformable rough terrain, is a challenging problem. Taking lateral skid into account, this paper presents a rough terrain model and nonholonomic kinematics model for planetary rovers. An approach is proposed in which the reference path is generated according to the planned path by combining look-ahead distance and path updating distance on the basis of the carrot following method. A path-following strategy for wheeled planetary exploration robots incorporating slip compensation is designed. Simulation results of a four-wheeled robot on deformable rough terrain verify that it can be controlled to follow a planned path with good precision, despite the fact that the wheels will obviously skid and slip.
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Modelos Teóricos , Robótica , AlgoritmosRESUMO
Fully actuated system (FAS) approach was proposed in 2020 and 2021 as a general framework for control system analysis and design based on a newly discovered general type of fully actuated models for dynamical systems. Due to its great advantages and power in dealing with complicated nonlinear time-varying and time-delay systems with possibly nonholonomic features, it has attracted much attention in the control community immediately since its birth. By now, numerous results have been produced for analysis and control of various types of complicated systems, which cover the topics of adaptive control, robust control, predictive control and fault-tolerant control, and involve time-varying and time-delay systems, discrete-time systems, stochastic systems and even impulsive systems. Meanwhile, a large number of applications have also been carried out. These include spacecraft control, aircraft and quadrotor control, robot control and control of power electronic systems and servo systems. In this article, an overview of the FAS approach is presented, ranging from models, basic theories, and control techniques to applications.
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In this article, the λ -policy iteration ( λ -PI) method for the optimal control problem of discrete-time linear systems is reconsidered and restated from a novel aspect. First, the traditional λ -PI method is recalled, and some new properties of the traditional λ -PI are proposed. Based on these new properties, a modified λ -PI algorithm is introduced with its convergence proven. Compared with the existing results, the initial condition is further relaxed. The data-driven implementation is then constructed with a new matrix rank condition for verifying the feasibility of the proposed data-driven implementation. A simulation example verifies the effectiveness of the proposed method.
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Although the literature on control of overhead crane systems is extensive and relatively mature, there is still a need to develop strategies that can simultaneously handle factors such as the double pendulum effect, variable cable length, input saturation, input dead zones, and external disturbances. This article is concerned with adaptive tracking control for underactuated overhead cranes in the presence of the above-mentioned challenging effects. The proposed controller is composed of the following two components. First, a tracking signal vector that effectively reduces system swing magnitudes is constructed to improve the transient performance and guarantee smooth operation of the system. Second, an adaptive law is designed to estimate and compensate for the overall effects of the friction, the external disturbances, and certain nonlinearities. The system stability has been proved rigorously via the Lyapunov method and Barbalat's lemma. Extensions to the cases with input saturation and dead zones have also been discussed. Extensive numerical simulations have been conducted to verify the performance and robustness of the proposed controller, in comparison to some existing methods.
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The region of attraction of the Lyapunov asymptotic stability at the origin is defined to be a ball centered at the origin, which is clearly simply connected and also bounded in the local case. In this article, the concept of substability is proposed, which allows "gaps" and "holes" in the region of attraction of the Lyapunov exponential stability, and also allows the origin to be a boundary point of the region of attraction. The concept is meaningful and useful in many practical applications, but is particularly made so with the control of single- and multi-order subfully actuated systems. Specifically, the singular set of a sub-FAS is first defined, and a substabilizing controller is then designed such that the closed-loop system is a constant linear one with an arbitrarily assignable eigen-polynomial, but with its initial values restricted within a so-called region of exponential attraction (ROEA). Consequently, the substabilizing controller drives all the state trajectories starting from the ROEA exponentially to the origin. The introduced concept of substabilization is of great importance because, on the one side, it is often practically useful since the designed ROEA is often large enough for certain applications, while on the other side, Lyapunov asymptotically stabilizing controllers can be further easily established based on substabilization. Several examples are given to demonstrate the proposed theories.
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A general time-varying nonlinear uncertain system with time-varying delays is proposed, which is composed of two subsystems: one is an uncertain fully actuated subsystem representing the controllable part in the system, the other is an isolated globally uniformly asymptotically (GUA) stable autonomous subsystem which represents the uncontrollable part in the system. Both the single-order fully actuated system (FAS) and the multiorder FAS representations of the controllable subsystem are introduced. The problem of robust stabilization of such a compound system with full-state feedback can be converted into an input-to-state GUA stabilization problem of the fully actuated subsystem, which is solved for both types of single- and multiorder FASs with very general assumptions on the uncertain perturbed functions. Under certain conditions, the solution reduces to that for robust stabilization with partial-state feedback, and naturally reduce to that for robust stabilization of FASs. Two illustrative examples demonstrate both the effect and the application procedure of the proposed robust stabilization approach.
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PURPOSE: Intracranial hemangiopericytomas (HPCs) are rare, and they have a tendency for local recurrence and metastases. The purpose of this study was to evaluate the relationship between CT perfusion (CTP) parameters and microvessel density (MVD) of HPCs and compare CTP parameters in parenchyma and peritumoral edema of HPCs. MATERIALS AND METHODS: The study was approved by the ethics committee, and written informed consent was obtained. Ten patients with HPCs and peritumoral edema, confirmed by pathological results, received 64-slice CT perfusion imaging before operation. To evaluate vascular attenuation of tumoral parenchyma, we immunostained the specimen sections for CD-34, measured the integrated optical density of all the positive stained CD-34 cells in the microscopic field, and calculated its ratio to total area of field as MVD. Perfusion analysis was calculated using the Patlak method. Using a 1-cm distance from the outer enhancing tumor margin as a boundary, the peritumoral edema was divided into an immediate and a distant part. The quantitative CTP parameters, including cerebral blood volume (CBV), permeability-surface area product (PS) of parenchyma, and immediate and distant peritumoral edemas, were compared. CBV and PS in parenchyma and immediate and distant peritumoral edemas of HPCs were also compared to their respective contralateral normal white matter. The correlations between MVD, CBV, and PS of tumoral parenchyma were analyzed. RESULTS: Positive correlations existed between CBV and MVD, PS and MVD (P < 0.05) respectively in the 10 patients. Furthermore, the values of CBV and PS in parenchyma of HPCs were significantly higher than those of the contralateral normal white matter and peritumoral edema (P < 0.05). The value of CBV in peritumoral edema of HPCs were lower than that of contralateral normal white matter (P < 0.05), while the value of PS in immediate and distant peritumoral edemas of HPCs were not significantly difference with that of contralateral normal white matter (P > 0.05). Finally, the values of CBV and PS did not show a significant difference between immediate and distant peritumoral edemas. CONCLUSIONS: CT perfusion imaging, especially determination of maximal CBV and corresponding PS values in the parenchyma, may be a useful and non-invasive technique for the preoperative evaluation of hemodynamic features of HPCs with peritumoral edema. CBV of peritumoral edema indicate that HPCs have a possibility of infiltration, this need further radiological-pathological research.
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Edema Encefálico/diagnóstico por imagem , Neoplasias Encefálicas/irrigação sanguínea , Hemangiopericitoma/irrigação sanguínea , Microvasos/diagnóstico por imagem , Doenças Raras , Adulto , Idoso , Feminino , Hemangiopericitoma/diagnóstico por imagem , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Doenças Raras/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodosRESUMO
Microbes are the drivers for disposing of organic solid waste (OSW) during aerobic fermentation. Notwithstanding, the significance of microbes is underestimated in numerous studies on aerobic fermentation product assessments. Here, we investigated the humification degree (HD), and the humic acid content was assessed in terms of the bacterial community. The bacterial communities were useful indicators for making predictions and even correctly determined the categories of OSWs with 94% accuracy. The bacterial codes can also provide a better prediction of HD. Our results demonstrate that the bacteria code is a reliable biological method to assess HD effectively. Bacterial codes can be used as ecological and biological indicators to evaluate the quality of aerobic fermentation of different materials.
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Compostagem , Bactérias , Substâncias Húmicas/análise , Esterco , Solo , Resíduos SólidosRESUMO
BACKGROUND: This study demonstrates a critical role in CNS innate immunity of the microglial Toll-like receptor 4 (TLR4) in the induction and maintenance of behavioral hypersensitivity in a rat model of bone cancer pain with the technique of RNA interference (RNAi). We hypothesized that after intramedullary injection of Walker 256 cells (a breast cancer cell line) into the tibia, CNS neuroimmune activation and subsequent cytokine expression are triggered by the stimulation of microglial membrane-bound TLR4. RESULTS: We assessed tactile allodynia and spontaneous pain in female Sprague-Dawley (SD) rats after intramedullary injection of Walker 256 cells into the tibia. In a complementary study, TLR4 small interfering RNA(siRNA) was administered intrathecally to bone cancer pain rats to reduce the expression of spinal TLR4. The bone cancer pain rats treated with TLR4 siRNA displayed significantly attenuated behavioral hypersensitivity and decreased expression of spinal microglial markers and proinflammatory cytokines compared with controls. Only intrathecal injection of TRL4 siRNA at post-inoculation day 4 could prevent initial development of bone cancer pain; intrathecal injection of TRL4 siRNA at post-inoculation day 9 could attenuate, but not completely block, well-established bone cancer pain. CONCLUSIONS: TLR4 might be the main mediator in the induction of bone cancer pain. Further study of this early, specific, and innate CNS/microglial response, and how it leads to sustained glial/neuronal hypersensitivity, might lead to new therapies for the prevention and treatment of bone cancer pain syndromes.
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Neoplasias Ósseas/complicações , Terapia Genética/métodos , Mielite/genética , Dor Intratável/genética , RNA Interferente Pequeno/farmacologia , Receptor 4 Toll-Like/genética , Animais , Citocinas/metabolismo , Modelos Animais de Doenças , Regulação para Baixo/efeitos dos fármacos , Regulação para Baixo/genética , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Hiperalgesia/genética , Hiperalgesia/imunologia , Hiperalgesia/terapia , Mediadores da Inflamação/metabolismo , Microglia/imunologia , Microglia/metabolismo , Mielite/imunologia , Mielite/terapia , Medição da Dor , Dor Intratável/imunologia , Dor Intratável/terapia , Interferência de RNA/fisiologia , RNA Interferente Pequeno/uso terapêutico , Ratos , Ratos Sprague-Dawley , Tíbia/patologia , Tíbia/fisiopatologia , Tíbia/cirurgia , Receptor 4 Toll-Like/antagonistas & inibidores , Resultado do Tratamento , Células Tumorais CultivadasRESUMO
Heavy metal ions (Ni(2+), Zn(2+), and Cr(3+)) can be effectively removed from real polynary metal ions-bearing electroplating wastewaters by a carbonation process, with â¼99% of metal ions removed in most cases. The synchronous formation of layered double hydroxide (LDH) precipitates containing these metal ions was responsible for the self-purification of wastewaters. The constituents of formed polynary metals-LDHs mainly depended on the Ni(2+):Zn(2+):Cr(3+) molar ratio in wastewaters. LDH was formed at pH of 6.0-8.0 when the Ni(2+)/Zn(2+) molar ratio ≥ 1 where molar fraction of trivalent metal in the wastewaters was 0.2-0.4, otherwise ZnO, hydrozincite, or amorphous precipitate was observed. In the case of LDH formation, the residual concentration of Ni(2+), Zn(2+), and Cr(3+) in the treated wastewaters was very low, about 2-3, â¼2, and â¼1 mg/L, respectively, at 20-80 °C and pH of 6.0-8.0, indicating the effective incorporation of heavy metal ions into the LDH matrix. Furthermore, the obtained LDH materials were used to adsorb azoic dye GR, with the maximum adsorption amount of 129-134 mg/g. We also found that the obtained LDHs catalyzed more than 65% toluene to decompose at 350 °C under ambient pressure. Thus the current research has not only shown effective recovery of heavy metal ions from the electroplating wastewaters in an environmentally friendly process but also demonstrated the potential utilization of recovered materials.
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Galvanoplastia , Hidróxidos/química , Metais Pesados/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Dióxido de Carbono/química , Cátions/química , Concentração de Íons de Hidrogênio , Resíduos Industriais/análise , Metalurgia , Purificação da Água/métodos , Difração de Raios XRESUMO
OBJECTIVE: To investigate antifungal activity of butenafine in comparison with that of natamycin, amphotericin B and fluconazole against ocular pathogenic filamentous fungi in vitro. METHODS: It was an experimental study. Susceptibility tests were performed against 260 isolates of ocular pathogenic filamentous fungi by broth dilution antifungal susceptibility test of filamentous fungi approved by the Clinical and Laboratory Standards Institute (CLSI) M38-A document. The isolates included Fusarium spp. (136), Aspergillus spp. (98), Alternaria alternata (9), Curvularia lunata (3), and unusual ocular pathogens (14). Final concentration ranged from 0.008 to 16.000 mg/L for butenafine, from 0.031 to 16.000 mg/L for amphotericin B and natamycin, and from 0.5 to 256.0 mg/L for fluconazole. Following incubation at 35 degrees C for 48 h, minimal inhibitory concentration (MIC) was determined according to the CLSI M38-A document. For amphotericin B and natamycin, the MIC was defined as the lowest drug concentration that prevented any discernible growth. For butenafine and fluconazole, the MIC was defined as the lowest concentration in which an approximately 75% reduction compared to the growth of the control was observed. Candida parapsilosis ATCC22019 was used as quality control strains to validated the results. Mean MIC and MIC range, the MIC at which 50% of the isolates tested were inhibited (MIC(50)) and the MIC at which 90% of the isolates tested were inhibited (MIC(90)), were provided for all the isolates tested by using descriptive statistical analysis with the statistical SPSS package (version 13.0). RESULTS: MIC(90) of butenafine, natamycin, amphotericin B and fluconazole were 4, 8, 2 and 512 mg/L for Fusarium spp., respectively; 0.063, 32.000, 2.000 and 256.000 mg/L for Aspergillus spp., respectively; 0.5, 8.0, 2.0 and 128.0 mg/L for Alternaria alternate, respectively; 0.125, 2.000, 0.500 and 4.000 mg/L for Curvularia lunata, respectively; and 1, 4, 1 and 256 mg/L for unusual ocular pathogens, respectively. CONCLUSIONS: Butenafine exhibits potent antifungal activity against a wide variety of ocular pathogenic fungi, especially for Aspergillus spp., Alternaria alternata, Curvularia lunata, and some unusual ocular pathogens and may have a role in future studies of antifungal eye drops and treating fungal keratitis.
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Antifúngicos/farmacologia , Benzilaminas/farmacologia , Fungos/efeitos dos fármacos , Naftalenos/farmacologia , Anfotericina B/farmacologia , Infecções Oculares Fúngicas/microbiologia , Fluconazol/farmacologia , Fungos/isolamento & purificação , Humanos , Testes de Sensibilidade Microbiana , Natamicina/farmacologiaRESUMO
We demonstrate a water-based synthetic route to fabricate composite inverse opals for simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Our process involves the conformal deposition of poly(3,4-ethylenedioxythiophene) (PEDOT) and PEDOT/Au on the skeletons of Ni inverse opals via cyclic voltammetric scans (CV) to initiate the electropolymerization of 3,4-ethylenedioxythiophene (EDOT) monomers. The resulting samples, Ni@PEDOT, and Ni@PEDOT/Au inverse opals, exhibit a three-dimensional ordered macroporous platform with a large surface area and interconnected pore channels, desirable attributes for facile mass transfer and strong reaction for analytes. Structural characterization and material/chemical analysis including scanning electron microscope, X-ray photoelectron spectroscopy, and Raman spectroscopy are carried out. The sensing performances of Ni@PEDOT and Ni@PEDOT/Au inverse opals are explored by conducting CV scans with various concentrations of AA, DA, and UA. By leveraging the structural advantages of inverse opals and the selection of PEDOT/Au composite, the Ni@PEDOT/Au inverse opals reveal improved sensing performances over those of conventional PEDOT-based nanostructured sensors.
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OBJECTIVE: To investigate antifungal activity of silver nitrate compared with fluconazole, ketoconazole and amphotericin B against ocular pathogenic fungi in vitro. METHODS: It was an experimental study. Susceptibility tests were performed against 260 isolates (15 genera and 29 species) of ocular pathogenic fungi by broth dilution antifungal susceptibility testing of filamentous fungi (M38-A) approved by National Committee for Clinical Laboratory Standards (NCCLS). Final concentrations ranged from 0.031 to 16.000 mg/L for silver nitrate, ketoconazole and amphotericin B, from 0.5 - 256.0 mg/L for fluconazole. Minimum inhibitory concentration (MIC) was defined as the lowest drug concentration that showed absence of growth or complete growth inhibition (100%). The end points were determined as 100% growth inhibition for silver nitrate and amphotericin B, and > or = 75% growth inhibition for ketoconazole and fluconazole. RESULTS: The MICs at which 90% of isolates were inhibited (MIC(90)) of silver nitrate, ketoconazole, amphotericin B and fluconazole were 2.000, 512.000, 32.000 and 2.000 mg/L for Fusarium species, respectively; 1.000, 256.000, 2.000 and 2.000 mg/L for Aspergillus species, respectively; 2.000, 128.000, 4.000 and 2.000 mg/L for Alternaria alternate, respectively; 2.000, 4.000, 0.125 and 0.500 mg/L for Curvularia lunata, respectively; and 1.000, 256.000, 1.000 and 1.000 mg/L for unusual ocular pathogens, respectively. Silver nitrate was highly active against Aspergillus species (92.9% susceptible at a MIC of < or = 1.0 mg/L) and Fusarium species (96.3% susceptible at a MIC of < or = 2.0 mg/L). 95.6% of Fusarium species and 90.8% of Aspergillus species exhibited resistance to fluconazole, 44.1% of Fusarium species and 42.9% of Aspergillus species exhibited resistance to amphotericin B, 66.2% of Fusarium species exhibited resistance to ketoconazole. The activity of silver nitrate against the fluconazole-resistant, ketoconazole-resistant and amphotericin B-resistant strains was high. CONCLUSION: Silver nitrate has promising activity against a wide variety of ocular pathogenic fungi in vitro, and may have a role in future studies of antifungal eye drops and treating fungal keratitis.
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Antifúngicos/farmacologia , Fungos Mitospóricos/efeitos dos fármacos , Nitrato de Prata/farmacologia , Infecções Oculares Fúngicas/microbiologia , Humanos , Ceratite/microbiologia , Testes de Sensibilidade Microbiana , Fungos Mitospóricos/isolamento & purificaçãoRESUMO
Oxidative stress is increasingly recognized as a central event contributing to the degeneration of dopaminergic neurons in the pathogenesis of Parkinson's disease (PD). Although reactive oxygen species (ROS) production is implicated as a causative factor in PD, the cellular and molecular mechanisms linking oxidative stress with dopaminergic neuron death are complex and not well characterized. The primary insults cause the greatest production of ROS, which contributes to oxidative damage by attacking all macromolecules, including lipids, proteins and nucleic acids, leading to defects in their physiological function. Consequently, the defects in these macromolecules result in mitochondrial dysfunction and neuroinflammation, which subsequently enhance the production of ROS and ultimately neuronal damage. The interaction between these various mechanisms forms a positive feedback loop that drives the progressive loss of dopaminergic neurons in PD, and oxidative stressmediated neuron damage appears to serve a central role in the neurodegenerative process. Thus, understanding the cellular and molecular mechanisms by which oxidative stress contributes to the loss of dopaminergic neurons may provide a promising therapeutic approach in PD treatment.
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Neurônios Dopaminérgicos/patologia , Mitocôndrias/patologia , Estresse Oxidativo , Doença de Parkinson/patologia , Animais , Morte Celular , Neurônios Dopaminérgicos/metabolismo , Humanos , Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , Doença de Parkinson/metabolismo , Espécies Reativas de Oxigênio/metabolismoRESUMO
Mitochondria are important organelles in virtually all eukaryotic cells, and are involved in a wide range of physiological and pathophysiological processes. Besides the generation of cellular energy in the form of adenosine triphosphate, mitochondria are also involved in calcium homeostasis, reactive oxygen species production and the activation of the intrinsic cell death pathway, thus determining cell survival and death. Mitochondrial abnormalities have been implicated in a wide range of disorders, including neurodegenerative disease such as Parkinson's disease (PD), and considered as a primary cause and central event responsible for the progressive loss of dopaminergic neurons in PD. Thus, reversion or attenuation of mitochondrial dysfunction should alleviate the severity or progression of the disease. The present review systematically summarizes the possible mechanisms associated with mitochondriamediated dopaminergic neuron damage in PD, in an attempt to elucidate the requirement for further studies for the development of effective PD treatments.
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Neurônios Dopaminérgicos/metabolismo , Mitocôndrias/genética , Doença de Parkinson/genética , Cálcio/metabolismo , Morte Celular/genética , Neurônios Dopaminérgicos/patologia , Humanos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/genéticaRESUMO
A type of generalized proportional-integral-derivative observers is proposed for descriptor linear systems. Based on a general parametric solution to a type of generalized Sylvester matrix equations, a parametric design approach for such observers is established. The proposed approach provides parameterizations for all the observer gain matrices, gives the parametric expression for the corresponding left eigenvector matrix of the observer system matrix, realizes the elimination of impulsive behaviors, and guarantees the regularity of the observer system. The design method can offer all the degrees of design freedom, which can be utilized to achieve various desired system specifications and performances. In addition, a numerical example is employed to show the design procedure and illustrate the effect of the presented approach.
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Algoritmos , Inteligência Artificial , Modelos Lineares , Reconhecimento Automatizado de Padrão/métodos , Simulação por ComputadorRESUMO
Lung cancer is the major form of cancer resulting in cancer-related mortality around the world. MicroRNAs are endogenous small non-coding single-stranded RNAs, which can engage in the regulation of gene expression. In this study, miR-18a-5p significantly upregulated in non-small cell lung cancer (NSCLC) tissues and NSCLC cell lines, suggesting an oncogenic function in lung cancer. Additionally, miR-18a-5p can promote carcinogenesis by directly targeting interferon regulatory factor 2 (IRF2). Further experiments indicated that IRF2 can increase cell apoptosis, inhibit cell proliferation and migration ability. Our study demonstrates that miR-18a-5p promotes autophagy in NSCLC. Collectively, these results indicate that miR-18a-5p can not only promote NSCLC by suppressing IRF2, but also will be a promising target in the near future.
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Carcinoma Pulmonar de Células não Pequenas/patologia , Fator Regulador 2 de Interferon/metabolismo , Neoplasias Pulmonares/patologia , MicroRNAs/metabolismo , Células A549 , Animais , Antagomirs/metabolismo , Autofagia , Sequência de Bases , Caderinas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/genética , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Receptores ErbB/metabolismo , Células HEK293 , Humanos , Fator Regulador 2 de Interferon/antagonistas & inibidores , Fator Regulador 2 de Interferon/genética , Antígeno Ki-67/metabolismo , Neoplasias Pulmonares/genética , Camundongos , Camundongos Nus , MicroRNAs/antagonistas & inibidores , MicroRNAs/genética , Alinhamento de Sequência , Regulação para CimaRESUMO
A parametric design approach for proportional-integral (PI) observers for continuous-time descriptor linear systems is proposed based on a complete general parametric solution to the generalized Sylvester matrix equation. The proposed approach provides complete parameterizations for all the observer gain matrices, gives the parametric expression for the corresponding finite left eigenvector matrix of the observer system matrix, realizes elimination of impulsive responses, and guarantees the regularity of the observer system. The design method offers all the degrees of design freedom, which can be utilized to achieve various desired system specifications and performances and, thus, has great potentials in applications. A numerical example is employed to show the design procedure and illustrate the effect of the proposed approach. Simulation results show a satisfactory tracking performance for descriptor linear systems.