广义时频分析方法在耳声发射研究中的应用 Ⅰ.仿真瞬态诱发耳声发射信号的时频分布

为了研究瞬态诱发耳声发射的时频分布,寻找其时频分布的最佳计算方法,首先筚计介绍了广时频分析方法,并描述了其中二次时频表示方法的特特点,然后用Ｗｉｇｎｅｒ分布及其改进型分布计算了仿真的瞬态诱发耳声发射信号的时频分布,通过对不同分布计算结果的比较,得出了锥形核分布最适合用于描述瞬态诱发耳声发射的时频分布。     

广义时频分析方法在耳声发射研究中的应用 Ⅰ.仿真瞬态诱发耳声发射信号的时频分布

为了研究瞬态诱发耳声发射的时频分布, 寻找其时频分布的最佳计算方法, 首先系统地介绍了广义时频分析方法,并描述了其中二次时频表示方法的特点,然后用Ｗｉｇｎｅｒ 分布及其改进型分布计算了仿真的瞬态诱发耳声发射信号的时频分布,通过对不同分布计算结果的比较,得出了锥形核分布最适合用于描述瞬态诱发耳声发射的时频分布。     

广义时频分析方法在耳声发射研究中的应用 Ⅱ.短声与短纯音诱发耳声发射信号的时频分布

为了进一步探讨耳声发射的产生机制,需要研究不同类型刺激诱发的耳声发射之间的相互关系,主要研究短声与短纯音诱发的耳声发射,用广义时频分析方法中的锥形核分布分别计算了它们的时频分布,从其时频分布分析了它们之间的相互关系。结果表明：具有不同中心频率的短纯音刺激诱发耳声发射的时频分布的迭加与短声刺激诱发的耳声发射的时频分布具有相似性,两者时频分布中的主要频率成分数目、潜伏期和持续时间完全相同,它们高度的相     

广义时频分析方法在耳声发射研究中的应用Ⅱ.短声与短纯音诱发耳声发射信号的时频分布

为了进一步探讨耳声发射的产生机制,需要研究不同类型刺激诱发的耳声发射之间的相互关系.主要研究短声与短纯音诱发的耳声发射,用广义时频分析方法中的锥形核分布分别计算了它们的时频分布,从其时频分布分析了它们之间的相互关系.结果表明:具有不同中心频率的短纯音刺激诱发耳声发射的时频分布的迭加与短声刺激诱发的耳声发射的时频分布具有相似性,两者时频分布中的主要频率成分数目、潜伏期和持续时间完全相同,它们高度的相关性支持了短声与短纯音诱发的耳声发射具有共同的产生器的观点.     

耳声发射信号的小波分析及应用

为了利用瞬态诱发耳声发射信号,对耳蜗性和蜗后性两种感音神经性耳聋进行诊断和定位,提出了一种基于小波变换的方法,用于对感音神经性耳聋病变进行诊断和定位。首先,获得听力正常耳信号的小波变换的对数均方根－频率曲线范围,及在对侧刺激声作用下,信号受抑制的小波变换的对数均方根－频率曲线范围;然后根据某一受试耳有无对侧刺激声作用下的瞬态诱发耳声发射信号,得出其小波变换的对数均方根曲线及受抑制的对数均方根曲线。最后,检测受试耳的两条曲线是否分别在正常值范围内,由此对受试耳的耳蜗及内侧橄榄耳蜗系统功能进行检测,同时根据每一条曲线将蜗性及蜗后病变定位到某一细致的频带。此方法与目前临床上采用的耳声发射结合ABR和纯音测听的诊断方法能很好地吻合。     

短纯音诱发耳声发射的指数方法时频分析

目的在于使用指数分布方法计算来自于正常人耳短纯音诱发耳声发射（Ｔｏｎｅ－ｂｕｒｓｔＥｖｏｋｅｄＯｔｏａｃｏｕｓｔｉｃＥｍｉｓｓｉｏｎｓ,ＴＢＯＡＥｓ）的时频分布。对耳声发射的定量分析依赖于谱方法,而ＴＢＯＡＥｓ是非平稳信号,因此传统的谱分析方法已不能满足要求,指数分布能很好地给出ＴＢＯＡＥｓ的时频表示。我们根据对仿真信号及实测ＴＢＯＡＥｓ的计算结果,分析了其时频分布的特点,并对不同的频率成份与潜伏期的关系进行了描述。     

瞬态刺激诱发耳声发射非线性特性的研究

耳声发射（ＯｔｏａｃｏｕｓｔｉｃＥｍｉｓｓｉｏｎｓ,ＯＡＥｓ）是目前对外周听觉系统是否完好无损评价的客观指标。瞬态刺激诱发的耳声发射（ＴｒａｎｓｉｅｎｔＥｖｏｋｅｄＯＡＥｓ,ＴＥＯＡＥｓ）在初始部分通常混杂有伪迹成份（主要指耳道对刺激声直接反射的回声）,这就使得ＯＡＥｓ的测量在临床使用中受到了很多的限制。因此,为了消除伪迹,一种称作“导出的非线性响应＂（ＤｅｒｉｖｅｄＮｏｎｌｉｎｅａｒｉｔｙＲｅｓｐｏｎｓｅ,ＤＮＬＲ）的非线性处理技术取代了传统的线性同步平均技术。本文的主要目的首先是根据听觉系统结构的特点建立了一个简单的模型,通过该模型解释了ＤＮＬＲ方法成立的第一个基本假设,然后根据对正常听力成年人耳朵的实测结果,计算了ＴＥＯＡＥｓ的输入／输出关系曲线,并证明了ＤＮＬＲ方法成立的第二个基本假设,最后对ＤＮＬＲ技术和同步平均技术进行了比较和分析,并且得到了一些有益的结论。     

瞬态诱发耳声发射的能量分布图

耳声发射是近年来耳科界研究的热点。文章提出以小波变换提取不同尺度下瞬态诱发耳声发射（ＴＥＯＡＥ）的小波信号,并以其平均能量作为特征参数,建立了ＴＥＯＡＥ能量分布图,为ＴＥＯＡＥ的定量频率分析提供新手段。ＴＥＯＡＥ能量分布图以正常人的平均能量作为０ｄＢ,以单侧５％位数作为９５％正常值范围,它体现了能量的损失情况,便于与纯音测听的结果相比较。ＴＥＯＡＥ能量分布图的建立,说明ＴＥＯＡＥ信号也包含了定量的频率信息,并提供了其定量分析的有效手段,有较好的临床应用前景     

诱发性耳声发射的掩蔽

３４例听觉正常受试者（共４８耳）进行疏波短声诱发性耳声发射（ＥＯＡＥ）掩蔽实验,项目包括同侧同时掩蔽、同侧后掩蔽和对倒后掩蔽。同时掩蔽的掩蔽声是稳态白噪声,后掩蔽的掩蔽声是宽带噪声。同侧同时掩蔽强度达３０ｄＢＳＬ时,未观察到对ＥＯＡＥ的掩蔽效应,但对主观听觉感受有掩蔽作用,表明ＥＯＡＥ的客观属性反映听觉行为有其局限性、同侧及对侧后掩蔽出现掩蔽效应时的掩蔽强度分别为３０和５０ｄＢＳＬ,掩蔽阈约分别为５９和６８ｄＢＳＬ。耳蜗的机械特性－非线性或耳蜗内存在的某种功能性的反馈调节系统可能是同侧后掩蔽的作用机理。下行的对侧橄榄耳蜗内侧束对外毛细胞主动收缩的抑制性作用,可有效解释对倒后掩蔽的ＥＯＡＥ变化。     

正常足月儿畸变产物耳声发射(DPOAEs)特性分析

研究提出正常足月儿畸变产物耳声发射（ＤＰＯＡＥｓ） 特性分析如下：１ ． ＤＰＯＡＥｓ 反应强度曲线,ＤＰ 图显示两个反应峰（ｆ２ ＝ １ ．６ 和５ ．０ ｋＨｚ） 和一个反应谷（ｆ２ ＝ ３ ．１ ～４ ．０ ｋＨｚ） ;２． ＤＰＯＡＥ 本底噪声及其特性,ｆ２ ＝ １．０ ｋＨｚ 其测试频率点（２ｆ１ －ｆ２） 本底噪声最高（Ｐ＜ ０ ．０５） ,ｆ２ ＝ ３ ．１ ,４．０ 和５ ．０ｋＨｚ ,测试频率点（２ｆ１ －ｆ２） 本底噪声较低（Ｐ＜ ０．０５） ;除ｆ２ ＝ ４．０ ｋＨｚ 外,ＤＰＯＡＥ 本底噪声与其反应强度均未呈现直线相关特性;３ ． ＤＰＯＡＥ ＳＮＲ 特性,ｆ２ ＝ １．０ ｋＨｚ 其ＳＮＲ 最小（Ｐ＝ ０．０００） ,ｆ２ ＝２ ．０ ｋＨｚ 其ＳＮＲ 最大（Ｐ０ ．００３） ;４． ＤＰＯＡＥ ＳＮＲ 和ＴＥＯＡＥ ＳＮＲ 相关特性,除１．０ ｋＨｚ 频段外,其余频段其二者间均有着非常显著的直线相关特性。     

Wrapping Up Greenhouse Gas Emissions An Assessment of GHG Emission Reduction Related to Efficient Packaging Use: An Assessment of GHG Emission Reduction Related to Efficient Packaging Use

The use of packaging materials results in greenhouse gas (GHG) emissions through production and transport of materials and packaging and through end-of-life management. In this article, we investigate the potential reduction of GHGs that are related to packaging. For this purpose, we use the dynamic MATTER-MARKAL model in which the western European energy and materials system is modeled. The results show that GHGs related to packaging can technically be reduced by up to 58% in the period 1995–2030. Current European packaging directives will result in a 10% emission reduction. Cost-effective improved material management 1 that includes lightweighting, reusable packages, material recycling, and related strategies can contribute a 22% GHG emission reduction. An additional 13% reduction becomes cost effective when a GHG emission penalty of 100 euros per metric ton 2 (EUR/ton) is introduced (1 EUR 0.9 USD). Generally speaking, improved material management dominates the gains that can be achieved without a penalty or with low GHG emission penalties (up to 100 EUR/ton CO2 equivalent). By contrast, the reduction of emissions in materials production and waste handling dominate when high GHG penalties are applied (between 100 and 500 EUR/ton CO2 equivalent). Given the significant technical potential and the low costs, more attention should be paid to material efficiency improvement in GHG emission reduction strategies.     

改良法建立妊娠期高血压疾病大鼠模型

目的寻找理想的妊娠期高血压疾病动物模型。方法60只雌性Wistar大鼠分为六组,分别为正常妊娠组（A组）、左旋亚硝酸精氨酸甲酯（L-NAME）腹腔注射组（B组）、生理盐水注射组（C组）、假手术组（D组）、双侧子宫动脉结扎术组（E组）以及L-NAME腹腔注射联合腹主动脉缩窄术组（F组）,对大鼠血压、尿蛋白值以及胎鼠、胎盘、胎鼠头的重量进行监测并观察肾脏、胎盘的病理改变。结果F组孕鼠于孕13d即出现了蛋白尿、血压升高,较B组及E组出现时间早（P〈0.05）,其胎鼠体重、胎头重量下降较各组更明显（P〈0.05）,肾小球小动脉管壁增厚、管腔狭窄;胎盘出现血管间膜增厚、纤维蛋白沉积等妊娠高血压疾病的典型病理改变。结论L-NAME腹腔注射联合腹主动脉缩窄术是更为理想的建立妊娠高血压疾病动物模型的方法。     

Otoacoustic emissions,auditory evoked potentials and self-reported gender in people affected by disorders of sex development (DSD)

Both otoacoustic emissions (OAEs) and auditory evoked potentials (AEPs) are sexually dimorphic, and both are believed to be influenced by prenatal androgen exposure. OAEs and AEPs were collected from people affected by 1 of 3 categories of disorders of sex development (DSD) — (1) women with complete androgen insensitivity syndrome (CAIS); (2) women with congenital adrenal hyperplasia (CAH); and (3) individuals with 46,XY DSD including prenatal androgen exposure who developed a male gender despite initial rearing as females (men with DSD). Gender identity (GI) and role (GR) were measured both retrospectively and at the time of study participation, using standardized questionnaires. The main objective of this study was to determine if patterns of OAEs and AEPs correlate with gender in people affected by DSD and in controls. A second objective was to assess if OAE and AEP patterns differed according to degrees of prenatal androgen exposure across groups. Control males, men with DSD, and women with CAH produced fewer spontaneous OAEs (SOAEs) – the male-typical pattern – than control females and women with CAIS. Additionally, the number of SOAEs produced correlated with gender development across all groups tested. Although some sex differences in AEPs were observed between control males and females, AEP measures did not correlate with gender development, nor did they vary according to degrees of prenatal androgen exposure, among people with DSD. Thus, OAEs, but not AEPs, may prove useful as bioassays for assessing early brain exposure to androgens and predicting gender development in people with DSD.     

An Improved Class of Estimators for Finite Population Mean in Sample Surveys

This paper proposes a class of estimators for estimating the finite population mean -Y of a study variate y using information on two auxiliary variates, one of which is positively and the other negatively correlated with the study variate y. An “asymptotically optimum estimator” (AOE) in the class is identified with its bias and mean square error formulae. It is observed that the proposed AOE is more efficient than Srivastava (1965), Srivastava (1974), Prasad (1989) and Gandge , Varghese , and Prabhu-Ajgaonkar (1993) estimators.     

一种改进的荧光共振能量转移方法分析同质二聚体内蛋白质-蛋白质相互作用

荧光共振能量转移(fluorescence resonance energy transfer, FRET)技术日益广泛的应用于检测活细胞中分子内和分子间的相互作用. 由于FRET仅发生于相互作用的供体和受体,即供体-受体复合物之间,所以检测的FRET信号必须经标准化处理以去除供体受体比例和浓度的影响然后才能够进行FRET的比较研究. 由于供体和受体的比例相同,分子内FRET的检测较为简单;而分子间FRET的检测存在更多的不确定因素,导致现有的方法很难精确定量.根据1类特殊的分子间相互作用,同质二聚体的独特特征,推导出供体 受体复合物的含量,进而开发了1种同质二聚体分子间FRET的精确定量的方法,以1种同质二聚体,雌激素受体α(estrogen receptor alpha, ERα)为供体和受体对,通过和其它的方法比较,证实了该方法用于FRET检测可获得更可靠的结果.     

The activity of Drosophila Hairless is required in pupae but not in embryos to inhibit Notch signal transduction

 Drosophila Hairless (H) encodes a negative regulator of Notch signalling. H activity antagonizes Notch (N) signalling during bristle development at the pupal stage. We show here by clonal analysis that H acts by inhibiting signal transduction rather than by promoting signal production, during both selection of microchaete precursors in the notum and vein cell differentiation in the wing. Allele-specific interactions further suggest that H inhibits Notch signal transduction by interacting directly with Suppressor of Hairless. Unexpectedly, this regulatory function of H appears to be essential only during imaginal development. Using a null allele of H that corresponds to a deletion of the H coding sequence, we show that embryos devoid of both maternal and zygotic gene products develop similarly to wild-type embryos. Thus, H activity is not strictly required to regulate N-mediated cell fate choices in the embryo. Received: 7 October 1997 / Accepted: 24 November 1997     

An analysis of relationships among plant community phenology and seasonal metrics of Normalized Difference Vegetation Index in the northern part of the monsoon region of China

This study focuses on relationships between the phenological growing season of plant communities and the seasonal metrics of Normalized Difference Vegetation Index (NDVI) at sample stations and pixels overlying them, and explores the procedure for determining the growing season of terrestrial vegetation at the regional scale, using threshold NDVI values obtained by surface–satellite analysis at individual stations/pixels. The cumulative frequency of phenophases has been calculated for each plant community and each year in order to determine the growing season at the three sample stations from 1982 to 1993. The precise thresholds were arbitrarily set as the dates on which the phenological cumulative frequency reached 5% and 10% (for the beginning) and 90% and 95% (for the end). The beginning and end dates of the growing season were then applied each year as time thresholds, to determine the corresponding 10-day peak greenness values from NDVI curves for 8-km² pixels overlying the phenological stations. According to a trend analysis, a lengthening of the growing seasons and an increase of the integrated growing season NDVI have been detected in the central part of the research region. The correlation between the beginning dates of the growing season and the corresponding threshold NDVI values is very low, which indicates that the satellite-sensor-derived greenness is independent of the beginning time of the growing season of local plant communities. Other than in spring, the correlation between the end dates of the growing season and the corresponding threshold NDVI values is highly significant. The negative correlation shows that the earlier the growing season terminates, the larger the corresponding threshold NDVI value, and vice versa. In order to estimate the beginning and end dates of the growing season using the threshold NDVI values at sites without phenological data from 1982 to 1993, we calculated the spatial correlation coefficients between NDVI time-series at each sample station and other contiguous sites year by year. The results provide the spatial extrapolation area of the growing season for each sample station. Thus, we can use the threshold NDVI value obtained at one sample station/pixel for a year to determine the growing season at the extrapolation sites with a similar vegetation type for the same year. Received: 25 October 2000 / Revised: 19 June 2001 / Accepted: 19 June 2001     

一种改进的PAE方法及其在锦鸡儿组(锦鸡儿属)特有性分析中的应用

针对特有性简约性分析（PAE）不足之处,提出一个新的改进分析方法。主要区别是,新方法对分布区内分类群区分了原始和演化,相应地编码为0／1;为了获取分类群原始和演化的特性,分析以分类群分支图为基础。新方法是系统发育与地理分布相统一原理的一个具体的定量化探讨。用新方法分析了豆科锦鸡儿属锦鸡儿组15种,结果表明新方法优于以前的PAE方法。用新的改进方法分析得到的可能的祖先分布区是原始类群树锦鸡儿和一大类属内原始类群的分布区。与目前属的起源问题的一般观点相一致。     

An analysis of proton fluxes coupled to electron transport and ATP synthesis in chloroplast thylakoids

Electron transport, phosphorylation and internal proton concentration were measured in illuminated spinach chloroplast thylakoid membranes under a number of conditions. Regardless of the procedure used to vary these parameters, the data fit a simple chemiosmotic model. Protons from Photosystem II did not appear to be utilized differently from those derived from Photosystem I. The maximal phosphorylation efficiency ($\text{P}\text{e}{}_2$) for photophosphorylation in washed thylakoids under oxidizing conditions is likely to be $\text{4}\text{3}$. This value is consistent with a proton-to-electron-pair ratio of 4 for electron flow through both photosystems and a proton-to-ATP ratio of 3 for the chloroplast proton-ATPase.     

An imbalance in autophagy contributes to retinal damage in a rat model of oxygen-induced retinopathy

In retinopathy of prematurity (ROP), the abnormal retinal neovascularization is often accompanied by retinal neuronal dysfunction. Here, a rat model of oxygen-induced retinopathy (OIR), which mimics the ROP disease, was used to investigate changes in the expression of key mediators of autophagy and markers of cell death in the rat retina. In addition, rats were treated from birth to postnatal day 14 and 18 with 3-methyladenine (3-MA), an inhibitor of autophagy. Immunoblot and immunofluorescence analysis demonstrated that autophagic mechanisms are dysregulated in the retina of OIR rats and indicated a possible correlation between autophagy and necroptosis, but not apoptosis. We found that 3-MA acts predominantly by reducing autophagic and necroptotic markers in the OIR retinas, having no effects on apoptotic markers. However, 3-MA does not ameliorate retinal function, which results compromised in this model. Taken together, these results revealed the crucial role of autophagy in retinal cells of OIR rats. Thus, inhibiting autophagy may be viewed as a putative strategy to counteract ROP.