∑-Δ调制器分组量化编码

∑-Δ调制器在对变化的交流测量信号实现A/D转换处理时可以省略复杂的数字抽取滤波器、抗混叠前置滤波器和采样保持器,直接转换计算。为充分减少数据冗余,加快转换计算速度,简化电路设计,采用分组量化编码方法。用多个计数器对调制器输出的1bit码流分别连续计数,DSP对计数结果计算处理。通过分组编码,可以方便的对调制器输出数据存储、处理,根据转换精度和转换速度要求灵活的选择利用前次转换的部分相关数据,而且电路实现和控制容易。给出了原理电路和计算分析结果,具有实用价值。

基于分组量化的高效超维计算分类方法

针对当前超维计算(hyperdimensional computing,HD)中大多数方法计算量大、效率低的问题,提出了一种基于分组量化的高效超维计算分类方法,在保证准确性的情况下提高HD模型的计算效率.该方法首先使用点积操作替代余弦相似度运算来降低HD计算推理阶段的计算量;其次,考虑到查询超向量的相似度计算随着类数的增加而增加,设计了一个分组查询方案,通过检查类的子集来减少相似度计算;最后,使用双值2次幂的量化方式来消除推理阶段的乘法运算,进一步提高计算速度.实验结果表明,与其他HD计算模型相比,所提方法性能优良,在相同的精度水平下,明显降低了能耗和执行时间.

舒适护理联合分组量化考核对胃食管反流微量射频治疗预后的影响

目的探讨舒适护理与分组量化考核在胃食管反流微量射频治疗中的应用及对患者预后的影响。方法选取我院收治的76例胃食管反流微量射频治疗患者为研究对象,随机分为研究组和对照组,各38例。研究组患者采用舒适护理,并对护理效果进行量化考核;对照组患者采用常规护理,对比分析两组患者的护理质量、舒适度、预后情况等。结果研究组患者CVRS评分、舒适度评分明显低于对照组(P<0.05)。研究组护理质量评分显著高于对照组(P<0.05)。研究组患者的术后黏膜损伤发生率为0.00%,出血率为5.26%,并发症发生率为7.89%,明显分别低于对照组的5.26%、15.79%、18.42%(P<0.05)。结论舒适护理联合分组量化考核应用于胃食管反流微量射频治疗患者中,可全面兼顾患者的身心舒适度,提高护理质量,对患者预后有积极的促进作用。

学生分组量化管理

在分析非正式群体在班级管理中优、劣势的基础上,提炼出学生分组量化管理,对该模式的目的、实施、特点三方面加以阐述,强调学生分组量化管理的良好效果和积极意义。

基于视觉掩蔽的半脆弱水印技术研究

以人眼视觉系统的掩蔽特性为基础,提出了一种基于分组量化的自适应半脆弱水印嵌入方案,该方案能够在不参考原始载体的情况下对数字图像同时进行版权保护和内容认证。仿真实验结果表明,所提出的半脆弱水印方案不仅具有较好的透明性,对JPEG压缩、叠加噪声、平滑滤波等常规图像处理操作具有较好的鲁棒性,而且能够对剪切、替换等恶意图像篡改做出报警并确定被篡改位置。同时常规图像处理下其误检率与漏检率均比较低。

用于图像内容认证的半脆弱水印嵌入算法

提出了一种用于图像内容认证的半脆弱水印嵌入算法,该算法以人眼视觉特性为基础,能够通过分组量化过程将水印信号自适应嵌入到原始图像的小波域内.该算法提取水印信息时不需要原始载体图像.仿真实验表明,本文算法不仅具有较好的透明性,而且对JPEG压缩、叠加噪声、平滑滤波等常见图像处理操作具有较好的鲁棒性,同时能够对剪切、替换等恶意图像篡改做出报警并确定被篡改位置.

Quantitative analysis of globularization and modeling of TC17 alloy with basketweave microstructure

The globularization behavior and mechanism of TC17 alloy with basketweave microstructure were investigated, and the models of dynamic and static globularization kinetics were established. The quantitative and metallographic results show that the globularization of α phase is sensitive to the parameters of deformation and heat treatment. By EBSD analysis, the formation and evolution mechanisms of intra-α boundaries are related to discontinuous dynamic recrystallization and continuous dynamic recrystallization, which can form α grains with high and low misorientations between neighbour grains after the heat treatment, respectively. Based on the globularization behavior and mechanism, two modified JMAK models are developed to predict the dynamic and static globularization kinetics, and the mean absolute relative errors(MARE) of 10.67% and 13.80% indicate the accuracy of the dynamic and static globularization kinetics models. The results of this work can provide guidance for controlling microstructure of titanium alloy.

Rice Repetitive DNA Sequence RRD3:a Plant Promoter and Its Application to RNA Interference

Previously, a moderately repetitive DNA sequence （RRD3） was cloned from rice （Oryza sativa L.） by DNA renaturation kinetics. Sequence analysis revealed several conserved promoter motifs, including four TATA-boxes and a CAAT-box, and promoter activity was shown in Escherichia coli and mammalian expression systems. Here, we inserted the RRD3 fragment into the plant promoter-capture vector, pCAMBIA1391Z, and examined whether the RRD3 fragment has promoter activity in plants. Transgenic tobacco and rice calli both showed β-glucuronidase （GUS） activity, indicating that RRD3 can act as a promoter in both monocot and dicot plants. Based on the promoter characteristic of RRD3, we designed a plant universal binary vector, pCRiRRD3, which is suitable for performing researches on plant RNA interference. This vector has two multiple cloning sites to facilitate sense and antisense cloning of the target sequence, separated by an intron fragment of 200 bp. The efficiency of the vector for gene silencing was assayed by histochemical and quantitative fluorometric GUS assays in transgenic tobacco. These research results suggested that this plant RNAi vector pCRiRRD3 can effectively perform gene silencing researches on both monocot and dicot plants.

Expression and significance of homeodomain protein Cdx2 in gastric carcinoma and precancerous lesions

AIM： To investigate the expression and significance of caudal-related homeobox transcription factor （Cdx2） in gastric carcinoma （GC） and precancerous lesions. METHODS： The expression of Cdx2 in GC, precancer- ous lesions and normal gastric mucosa were detected using immunohistochemical method. Hematoxylin and eosin staining, alcian blue/periodic acid-schiff and high iron diamine/alcian blue staining were used to classify intestinal metaplasia （IM） and GC. RESULTS： Cdx2 was not detected in normal gas- tric mucosa. Cdx2 expression was detected in 87.1% （101/116） of IM, 50% （36/72） of dysplasia and 48.2% （41/85） of GC. The Cdx2-expressing cells in IM were more prevalent than in dysplasia and carcinoma （P 〈 0.05）. There was no relationship between Cdx2 ex- pression and the classification of IM or the degree of dysplasia. Expression of Cdx2 was significantly higher in intestinal-type carcinoma than in diffuse and mixed- type carcinoma （P 〈 0.05）. Positive expression of Cdx2was mainly found in moderately to well differentiated GC. There was a negative association between nuclear Cdx2 expression and lymph node metastasis and tumor, nodes, metastasis stage of GC （P 〈 0.05）. The patients with Cdx2-positive expression showed a higher survival rate than those with Cdx2-negative expression （P = 0.038）. Multivariate analysis revealed that the expres- sion of Cdx2 and lymph node metastasis were indepen- dent prognostic indicators of GC （P 〈 0.05）.

EVALUATION OF GEOCHEMICAL QUALITY CONTROLIN DETERMINATION OF Mn IN SOILS USING A SEQUENTIAL CHEMICAL EXTRACTION

Sequential chemical extraction procedure has been widely used to partition particulate trace metals into various fractions and to describe the distribution and the statue of trace metals in geo environment. One sequential chemical extraction procedure was employed here to partition various fractions of Mn in soils. The experiment was designed with quality controlling concept in order to show sampling and analytical error. Experimental results obtained on duplicate analysis of all soil samples demonstrated that the precision was less than 10%(at 95%confidence level). The accuracy was estimated by comparing the accepted total concentration of Mn in standard reference materials (SRMs) with the measured sum of the individual fractions. The recovery of Mn from SRM1 and SRM2 was 94.1%and 98.4%, respectively. The detection limit, accuracy and precision of the sequential chemical extraction procedure were discussed in detailed. All the results suggest that the trueness of the analytical method is satisfactory.

Properties of Bio-oil from Fast Pyrolysis of Rice Husk

Physicochemical properties of bio-oil obtained from fast pyrolysis of rice husk were studied in the present work.Molecular distillation was used to separate the crude bio-oil into three fractions viz.light fraction,middle fraction and heavy fraction.Their chemical composition was analyzed by gas chromatograph and mass spectrometer（GC-MS）.The thermal behavior,including evaporation and decomposition,was investigated using thermogravimetric analyzer coupled with Fourier transform infrared spectrometer（TG-FTIR）.The product distribution was significantly affected by contents of cellulose,hemicellulose and lignin.The bio-oil yield was 46.36%（by mass） and the yield of gaseous products was 27%（by mass）.The chemicals in the bio-oil included acids,aldehydes,ketones,alcohols,phenols,sugars,etc.The light fraction was mainly composed of acids and compounds with lower boiling point temperature,the middle and heavy fractions were consisted of phenols and levoglucosan.The thermal stability of the bio-oil was determined by the interactions and intersolubility of compounds.It was found that the thermal stability of bio-oil was better than the light fraction,but worse than the middle and heavy fractions.

Quantitative analysis of diffusion-weighted magnetic resonance images:differentiation between prostate cancer and normal tissue based on a computer-aided diagnosis system

Diffusion-weighted imaging(DWI) is considered to be one of the dominant modalities used in prostate cancer(PCa) detection and the assessment of lesion aggressiveness,especially for peripheral zone(PZ) PCa.Computer-aided diagnosis(CAD),which is capable of automatically extracting and evaluating image features,can integrate multiple parameters and improve the detection of PCa.In this study,13 quantitative image features were extracted from DWI by CAD,and diagnostic efficacy was analyzed in both the PZ and transition zone(TZ).The results demonstrated that there was a significant difference(P<0.05) between PCa and non-PCa for nine of the 13 features in the PZ and five of the 13 features in the TZ.Besides,the prediction outcome of CAD had a strong correlation with the DWI scores that were graded by experienced radiologists according to the Prostate Imaging-Reporting and Data System Version 2(PI-RADS v2).

Differentiation of rat adipose tissue-derived mesenchymal stem cells towards a nucleus pulposus-like phenotype in vitro

Objective： To differentiate rat adipose tissue-derived mesenchymal stem cells （ADSCs） into cells with a nucleus pulposus-like phenotype in vitro, so as to lay a foundation for the cell-based transplantation therapy of degenerated intervertebral discs. Methods： Rat ADSCs were isolated only from the subcutaneous inguinal region and purified by limited dilution. ADSCs of the third passages were analyzed by fluorescence activated cell sorter （FACS） to detect the cell surface markers （Sca-1, CD44, CD45, CDI lb）. To induce ADSCs to- wards a nucleus pulposus-like phenotype, ADSCs were immobilized in 3-dimensional alginate hydrogels and cultured in an inducing medium containing transforming growth factor-beta1 （TGF- β1） under hypoxia （2% O2）, while control groups under normoxia （21% O2） in alginate beads in medium with or without the presence of TGF-β 1. Semiquantitative reverse transcription polymerase chain reaction （RT-PCR） was carried out to evaluate phenotypic and biosynthetic activities in the process of differentiation. Meanwhile, Alcian blue staining were used to detect the formation of sulfated glycosaminoglycans （GAGs） in the differentiated cells. Results： The purified ADSCs were fibroblast-like and proliferated rapidly in vitro. The flow cytometry showed that ADSCs were positive for Sca-1 and CD44, negative for CD45 and CD11b. The results of RT-PCR manifested that the gene expressions of Sox-9, aggrecan and collagen Ⅱ, which were chondrocyte specific, were upregulated in medium containing TGF-β1 under hypoxia （2% O2）. Likewise, gene expression of HIF-1 a, which was characteristics of in- tervertebral discs, was also upregulated. Simultaneously, Alcian blue staining exhibited the formation of many GAGs. Conclusions： The approach in our experiment is a simple and effective way to acquire a large quantity of homogenous ADSCs. Rat ADSCs can be differentiated into nucleus pulposus-like cells. ADSCs may replace bone marrow mesenchymal stem cells as a new kind of seed cells in regeneration of degenerated intervertebral discs using cell transolantation therarw.

Chemical profile of the active fraction of Yi-Gan San by HPLC–DAD–Q-TOF–MS and its neuroprotective effect against glutamate-induced cytotoxicity

Yi-Gan San(YGS), a traditional Chinese medicine for dementia-related symptoms, was previously fractionated. One active fraction, YGS40 exhibited a neuroprotective effect against glutamate-induced cytotoxicity. In the present study, high-performance liquid chromatography, coupled with diode-array detection and quadrupole time-of-flight mass spectrometry, was applied for the identification of its chemical constituents and for quantification studies. The chemical profile of YGS40 consisted of sixty-four identified or tentatively characterized compounds. The levels of the major marker compounds increased significantly in the mixed decoction compared with those in the single plant decoction. The results suggest the high precision of the analyses of most of the constituents in YGS40 and establish the quantitative variations of the major marker compounds between the single and mixed decoction processes.

Laboratory Testing of Magnetic Tracers for Soil Erosion Measurement

Soil erosion, which includes soil detachment, transport, and deposition, is one of the important dynamic land surface processes. The magnetic tracer method is a useful method for studying soil erosion processes. In this study, five types of magnetic tracers were made with fine soil, fly ash, cement, bentonite, and magnetic powder （reduced iron powder） using the method of disk granulation. The tracers were uniformly mixed with soil and tested in the laboratory using simulated rainfall and inflow experiments to simulate the interrill and rill components of soil erosion, in order to select one or more tracers which could be used to study detachment and deposition by the erosive forces of raindrops and surface flow of water on a slope. The results showed that the five types of magnetic tracers with high magnetic susceptibility and a wide range of sizes had a range of 0.99-1.29 gcm-3 in bulk density. In the interrill and rill experiments, the tracers FC1 and FC2 which consisted of fly ash and cement at ratios of 1：1 and 2：1, respectively, were transported in phase with soil particles since the magnetic susceptibility of sediment approximated that of the soil which was uneroded and the slopes of the regression equations between the detachment of sediment and magnetic tracers FC1 and FC2 were very close to the expected value of 20, which was the original soil/tracer ratio. The detachment and deposition on slopes could be accurately reflected by the magnetic susceptibility differences. The change in magnetic susceptibility depended on whether deposition or detachment occurred. However, the tracer FS which consisted of fine soil and the tracers FB1 and FB2 which consisted of fly ash and bentonite at ratios of 1：1 and 2：1, respectively, were all unsuitable for soil erosion study since there was no consistent relationship between sediment and tracer detachment for increasing amounts of runoff. Therefore, the tracers FC1 and FC2 could be used to study soil erosion by water.

Monopole and Coulomb Field as Duals within the Unifying Reissner–Nordstrm Geometry

We are going to prove that the Monopole and the Coulomb fields are duals within the unifying structure provided by the Reissner–Nordstr¨om spacetime. This is accomplished when noticing that in order to produce the tetrad that locally and covariantly diagonalizes the stress-energy tensor, both the Monopole and the Coulomb fields are necessary in the construction. Without any of them it would be impossible to express the tetrad vectors that locally and covariantly diagonalize the stress-energy tensor. Then, both electromagnetic fields are an integral part of the same structure, the Reissner–Nordstr¨om geometry.