555单稳态触发器的触发特性分析

为研究单稳态触发器的触发特性,分析了555单稳态触发器的触发特性,研究了电路输出状态与外加触发信号的关系。分析了输入触发信号为周期性脉冲信号时输出信号对输入信号的分频作用,从而扩展了单稳态触发器的应用方向。Multisim仿真实验证明了所述观点正确性。

Role of cyclooxygenase-2 gene polymorphisms in pancreatic carcinogenesis

AIM:To evaluate the clinical significance of-765G/C and-1195G/A cyclooxygenase-2 (COX-2) gene polymorphisms in patients with pancreatic cancer (PC).METHODS:The study included 201 patients:85 with PC and 116 healthy controls.-765G/C and-1195G/A COX-2 gene polymorphisms were studied in DNA isolated from blood samples.The associations of the analyzed genotypes and clinical data at diagnosis were evaluated.RESULTS:We found an increased frequency of the homozygous-1195AA COX-2 genotype in patients with PC (53.7%) compared with the control group (21%) (P < 0.01).In contrast,the distribution of genotypeand allele frequencies of the-765G/C COX-2 polymorphism in the PC patients were not different from those in control groups.A correlation between presence of homozygous-1195AA COX-2 genotype and tumor size > 3 cm was observed (P < 0.05).Analyzed polymorphisms were unrelated to the patients' sex and age,nor to the presence of regional or distant metastases.CONCLUSION:These preliminary results indicate that the-1195G/A COX-2 polymorphism may play an important role in PC prognosis and carcinogenesis.

MIMO-OFDM Scheme Using ApFFT over 3GPP SCM Channels

The all-phase fast Fourier transform (apFFT) is proposed as a digital demodulation algorithm in place of the fast Fourier transform (FFT) for orthogonal frequency division multiplexing (OFDM) based multiple-input multiple-output (MIMO) communication systems. The amplitude spectrum of apFFT-demodulated symbols is the square of that of the FFT, which helps reduce the Gaussian noise to a great extent. Moreover, the phases of apFFT symbols are not affected by the frequency shift between the transmitter and receiver oscillators. These properties particularly appeal to MIMO systems over frequency-selective fading channels. The proposed MIMO-OFDM system employing the apFFT is validated using the spatial channel model (SCM) proposed by the third generation partnership project (3GPP). The simulation results demonstrate that the performance of the proposed system after compensating for the rate loss due to zero bits inserted in the space-frequency OFDM (SF-OFDM) coding scheme, still considerably outperforms the conventional system over 3GPP SCM channels, especially under poor channel conditions.

Study on the Interaction Between Tangerine Peel and Beer by Absorption Spectrum

This paper presents a new method to study the interaction between tangerine peel and beer by absorption spectrum.The author explores the change laws and the differences of the absorbance on some wave band from the absorption spectrums of tangerine peel and the mixture of tangerine peel and beer. The results show that there is an obvious difference around 323 nm though the absorbance values of the two samples are almost similar in the most bands. The absorbance value of the mixture is obviously greater than that of tangerine peel at 276 nm in the spectrums, and there is a shift of the peak position in the absorption spectrum of the mixture, which shows the differences of the absorbance values and the peak positions of the two samples. Through comparing the characteristics of the two samples' absorption spectrums, a new method for researching new pharmacological action of tangerine peel is presented in this paper. The result indicates that the technology of spectrum analysis will play an important role in the research and development of Chinese herbal pharmacology and new pharmacology.

Investigation of the two-quasiparticle bands in the doubly-odd nucleus ^(166)Ta using a particle-number conserving cranked shell model

The high-spin rotational properties of two-quasiparticle bands in the doubly-odd 166Ta are analyzed using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency hw are reproduced very well by the particle-number conserving calculations, which provides a reliable support to the configuration assignments in previous works for these bands. The backbendings in these two-quasiparticle bands are analyzed by the calculated occupation probabilities and the contributions of each orbital to the total angular momentum alignments. The moments of inertia and alignments for the Gallagher-Moszkowski partners of these observed two-quasiparticle rotational bands are also predicted.

Invariant Measures and Asymptotic Gaussian Bounds for Normal Forms of Stochastic Climate Model

The systematic development of reduced low-dimensional stochastic climate models from observations or comprehensive high dimensional climate models is an important topic for atmospheric low-frequency variability,climate sensitivity,and improved extended range forecasting.Recently,techniques from applied mathematics have been utilized to systematically derive normal forms for reduced stochastic climate models for low-frequency variables.It was shown that dyad and multiplicative triad interactions combine with the climatological linear operator interactions to produce a normal form with both strong nonlinear cubic dissipation and Correlated Additive and Multiplicative(CAM) stochastic noise.The probability distribution functions(PDFs) of low frequency climate variables exhibit small but significant departure from Gaussianity but have asymptotic tails which decay at most like a Gaussian.Here,rigorous upper bounds with Gaussian decay are proved for the invariant measure of general normal form stochastic models.Asymptotic Gaussian lower bounds are also established under suitable hypotheses.