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This paper discusses the impact of the adjacent channels on the 1-dB compression point, the IP3 and the IP5 of Radio Frequency (RF) amplifier by n-tone test. By combining the theoretical derivation and software simulation, the model analysis for the third/five order polynomial nonlinear amplifier has been achieved. Moreover, the control variable method is adopted to draw the curves for the input/output signals. The research shows that the 1-dB compression point, the IP3 and the IP5 drop as n increases, and they all have symmetry for a given n. The fifth-order polynomial nonlinear amplifier model is proposed, the research shows that the adjacent channels have a great impact on the 1-dB compression point, the IP3 and the IP5 of the desired channel. This effect must be taken into account in actual RF amplifier designs and wireless communication architectures. [ABSTRACT FROM AUTHOR]

In this paper, the implementation and electro-migration (EM) study in GaAs pHEMT stacked distributed power amplifier (SDPA) is presented. A 0.2 − 7 GHz PA is designed using a 0.15 μ m GaAs pHEMT process, which employs 4-distributed 2-stacked-field effect transistors (FETs) to obtain about 1-watt output power with corresponding power added efficiency (PAE) of 26–32% within a very small chip size of 2.9 mm2. Using the finite element analysis (FEA), the EM prediction for an SDPA is achieved effectively to find the weakest spot for the stacked distributed PA. This can provide valuable guidance for circuit design and analysis. [ABSTRACT FROM AUTHOR]

Aims The aims of this study are to apply a theory-based mechanistic model to describe the pharmacokinetics (PK) and pharmacodynamics (PD) of S- and R-warfarin. Methods Clinical data were obtained from 264 patients. Total concentrations for S- and R-warfarin were measured by ultra-high performance liquid tandem mass spectrometry. Genotypes were measured using pyrosequencing. A sequential population PK parameter with data method was used to describe the international normalized ratio (INR) time course. Data were analyzed with NONMEM. Model evaluation was based on parameter plausibility and prediction-corrected visual predictive checks. Results Warfarin PK was described using a one-compartment model. CYP2C9 *1/*3 genotype had reduced clearance for S-warfarin, but increased clearance for R-warfarin. The in vitro parameters for the relationship between prothrombin complex activity (PCA) and INR were markedly different (A = 0.560, B = 0.386) from the theory-based values (A = 1, B = 0). There was a small difference between healthy subjects and patients. A sigmoid Emax PD model inhibiting PCA synthesis as a function of S-warfarin concentration predicted INR. Small R-warfarin effects was described by competitive antagonism of S-warfarin inhibition. Patients with VKORC1 AA and CYP4F2 CC or CT genotypes had lower C50 for S-warfarin. Conclusion A theory-based PKPD model describes warfarin concentrations and clinical response. Expected PK and PD genotype effects were confirmed. The role of predicted fat free mass with theory-based allometric scaling of PK parameters was identified. R-warfarin had a minor effect compared with S-warfarin on PCA synthesis. INR is predictable from 1/PCA in vivo. [ABSTRACT FROM AUTHOR]

Isoproterenol (ISO)-induced myocardial ischemia animal model has been widely applied to the study of myocardial ischemia and evaluation of drug efficacy. Metabolic profiling of endogenous compounds can make a deep insight into biochemical process of the ISO-induced myocardial ischemia rats. Herein, rats were treated with ISO (2 mg x kg(-1)) for 10 days. After the model was established by measuring myocardial histopathology and plasma creatine kinase, GC/TOF-MS was used to determine endogenous metabolites in plasma and cardiac muscle of rats, and pattern recognition was used to process the data. Results showed that the plasma metabolic profiling of ISO-induced myocardial ischemia rats was significantly different from that of the control, and it had the tendency to the normal state after the discontinue of ISO injection. Besides, the cardiac muscle of rats treated with ISO for 10 days and the normal cardiac muscle could also be separated clearly. The potential biomarkers in plasma and cardiac muscle of model rats had homogeneity and their own specialty. Biochemical metabolic pathway analysis indicated that this myocardial ischemia model was involved in the alternation of energy metabolism, saccharometabolism, lipid metabolism, nucleoside metabolism and amino acid metabolism, and in relationship with oxidative stress. These findings revealed that metabonomics may be a promising tool to evaluate myocardial ischemia rat model induced by ISO and could further extend the study of pharmacodynamic action of drugs at the molecular level.

In order to explore the scientific connotation of "Fangzhengduiying (formula corresponding to pattern types)", "Qiyinliangxuzheng (Qi and Yin deficiency pattern)" of myocardial ischemia rat model and GC-TOF/MS based metabonomic method were used for comparing the effects of Sheng-mai injection, Salvia injection and propranolol in the present study. After data processing and pattern recognition, Sheng-mai injection showed better efficacy than the other two drugs in accordance with not only visual observation from PLS-DA scores plots but also the number of abnormal endogenous compounds restored to the normal level. Further studies showed that Sheng-mai injection could normalize the level of plasma endothelin-1, the index related to cardiovascular diseases and sleep disorders, which verified the results of metabonomics. Finally, the regulated metabolites and related metabolic pathways were analyzed, and it was supposed that the effects of Sheng-mai injection involved in the alternation of energy metabolism, lipid metabolism, amino acids metabolism, and so on. These findings provided scientific evidence to Shengmai "Fang" used for "Qi and Yin deficiency pattern" correspondingly, indicating that metabonomics has great potential in traditional Chinese medical research, which provides a novel approach and way to modernization of traditional Chinese medicine.

The global metabolite profiles of endogenous compounds of Wistar rats from 12 to 20 weeks old were investigated to take deep insight into and get better understanding of the pathogenesis of development and aging. Plasma from Wistar rats at 12, 14, 16, 18, and 20 weeks old were analyzed using GC/TOFMS. Multivariate data analysis was then used to process the metabonomic data which indicated excellent separation between different weeks and showed that the metabolic profiles of the samples changed with age, enabling age-related metabolic trajectories to be visualized. Decreased concentrations of citric acid, cis-aconitic acid, 9-(z)-hexadecenoic acid along with increased levels of hexanedioic acid, alpha-tocopherol, 3-indole propionic acid, etc contributed to the separation. Several major metabolic pathways were identified to be involved in metabolic regulation. This suggests that GC/TOFMS-based metabonomics is a powerful alternative approach to identifying potential biomarkers and investigating the physiological developments of aging and it is important to employ suitable age-match control group in metabonomic study of physiological monitoring, drug safety assessment, and disease diagnosis, etc.