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。     

Effects of GSM cellular phones on human hearing: the European project "GUARD"

The European multicenter project named GUARD involved nine centers and aimed to assess potential changes in auditory function as a consequence of exposure to low-intensity electromagnetic fields (EMFs) produced by GSM cellular phones. Participants were healthy young adults without any evidence of hearing or ear disorders. Auditory function was assessed immediately before and after exposure to EMFs, and only the exposed ear was tested. The procedure was conducted twice in a double blinded design, once with a genuine EMF exposure and once with a sham exposure (at least 24 h apart). Tests for assessment of auditory function were hearing threshold level (HTL), transient otoacoustic emissions (TEOAE), distortion product otoacoustic emissions (DPOAE), and auditory brainstem response (ABR). The exposure consisted of speech at a typical conversational level delivered via an earphone to one ear, plus genuine or sham EMF exposure. The EMF exposure used the output of a software-controlled consumer cellular phone at full power for 10 min. A system of phone positioning that allowed participants to freely move their heads without affecting exposure was used. Analysis of the data showed there were no effects of exposure to GSM mobile phone signals on the main measures of the status of the auditory system.     

Assignment of relevés to pre‐defined classes by supervised clustering of plant communities using a new composite index

Question: How does a newly designed method of supervised clustering perform in the assignment of relevé (species composition) data to a previously established classification. How do the results compare to the assignment by experts and to the assignment using a completely different numerical method? Material: Relevés analysed represent 4186 Czech grassland plots and 4990 plots from a wide variety of vegetation types (359 different associations or basal communities) in The Netherlands. For both data sets we had at our disposal an expert classification, and for the Czech data we also had available a numerical classification as well as a classification based on a neural network method (multi‐layer perceptron). Methods: Two distance indices, one qualitative and one quantitative, are combined into a single index by weighted multiplication. The composite index is a distance index for the dissimilarity between relevés and vegetation types. For both data sets the classifications by the new method were compared with the existing classifications. Results: For the Czech grasslands we correctly classified 81% of the plots to the classes of an expert classification at the alliance level and 71% to the classes of the numerical classification. Correct classification rates for the Dutch relevés were 64, 78 and 83 % for the lowest (subassociation or association), association, and alliance level, respectively. Conclusion: Our method performs well in assigning community composition records to previously established classes. Its performance is comparable to the performance of other methods of supervised clustering. Compared with a multi‐layer perceptron (a type of artificial neural network), fewer parameters have to be estimated. Our method does not need the original relevé data for the types, but uses synoptic tables. Another practical advantage is the provision of directly interpretable information on the contributions of separate species to the result.     

Comparison of transient otoacoustic emission responses from neonatal and adult ears.

Transient otoacoustic emission (TEOAE) responses from neonatal (age: 48 h) and adult subjects (age: 26.6 +/- 10.0 yr) were analyzed by the combined use of recurrence quantification analysis and singular value decomposition. The data from the two age groups showed significant differences and similarities. The neonatal responses presented less deterministic structures than those of the adults in terms of recurrent dynamic features. In both data sets, the same high level of individual specific dynamic features was observed. The results from the singular value decomposition analysis suggest that a large percentage of variability in all of the analyzed responses can be explained by four to five essential modes. This number is lower than that observed in simulated TEOAE responses generated by a five-component gammatone model. A possible explanation is presented, based on simple instrumental and morphoanatomic considerations.     

The prevalence and expression of inherited connexin 26 mutations associated with nonsyndromic hearing loss in the Israeli population

Connexin 26 (GJB2) mutations lead to hearing loss in a significant proportion of all populations studied so far, despite the fact that at least 50 other genes are also associated with hearing loss. The entire coding region of connexin 26 was sequenced in 75 hearing impaired children and adults in Israel in order to determine the percentage of hearing loss attributed to connexin 26 and the types of mutations in this population. Age of onset in the screened population was both prelingual and postlingual, with hearing loss ranging from moderate to profound. Almost 39% of all persons tested harbored GJB2 mutations, the majority of which were 35delG and 167delT mutations. A novel mutation, involving both a deletion and insertion, 51del12insA, was identified in a family originating from Uzbekistan. Several parameters were examined to establish whether genotype-phenotype correlations exist, including age of onset, severity of hearing loss and audiological characteristics, including pure-tone audiometry, tympanometry, auditory brainstem response (ABR), and transient evoked otoacoustic emissions (TEOAE). All GJB2 mutations were associated with prelingual hearing loss, though severity ranged from moderate to profound, with variability even among hearing impaired siblings. We have not found a significant difference in hearing levels between individuals with 35delG and 167delT mutations. Our results suggest that, in Israel, clinicians should first screen for the common 167delT and 35delG mutations by simple and inexpensive restriction enzyme analysis, although if these are not found, sequencing should be done to rule out additional mutations due to the ethnic diversity in this region.     

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     

A systematic review on the effect of low-dose radiation on hearing

Numerous studies have documented the adverse effects of high-dose radiation on hearing in patients. On the other hand, radiographers are exposed to a low dose of ionizing radiation, and the effect of a low dose of radiation on hearing is quite abstruse. Therefore, the present systematic review aimed to elucidate the effect of low-dose ionizing radiation on hearing. Two authors independently carried out a comprehensive data search in three electronic databases, including PUBMED/MEDLINE, CINAHL, and SCOPUS. Eligible articles were independently assessed for quality by two authors. Cochrane Risk of Bias tool was used assess quality of the included studies. Two articles met the low-dose radiation exposure criteria given by Atomic Energy Regulatory Board (AERB) and National Council on Radiation Protection (NCRP) guidelines. Both studies observed the behavioral symptoms, pure-tone hearing sensitivity at the standard, extended high frequencies, and the middle ear functioning in low-dose radiation-exposed individuals and compared with age and gender-matched controls. One study assessed the cochlear function using transient-evoked otoacoustic emissions (TEOAE). Both studies reported that behavioral symptoms of auditory dysfunction and hearing thresholds at extended high frequencies were higher in radiation-exposed individuals than in the controls. The current systematic review concludes that the low-dose ionizing radiation may affect the hearing adversely. Nevertheless, further studies with robust research design are required to explicate the cause and effect relationship between the occupational low-dose ionizing radiation exposure and hearing.

     

植物生活史型定量划分及其权重配置方法——以四棱豆生活史型划分为例

植物生活史型定量划分方法研究是植物生活史型研究的重要内容。现有的生活史型定量划分方法是基于主成分分析法(PCA)建立起来的,未考虑性状指标之间的相互影响,因此需要探索适用于"网状"结构指标体系的植物生活史型划分新方法。根据植物生活史型划分指标的层次性特点,以攀援型和矮生型四棱豆(Psophocarpus tetragonolobus)为例,分别采用主成分分析法(PCA)、层次分析法(AHP)和网络层次分析法(ANP)对性状指标进行权重配置,计算性状指标的综合得分和生活史型划分参数,结果如下:与ANP相比,PCA计算的V型(营养生长型)参数值偏低(x在0.39以下),S型(有性生殖型)参数值偏高(z在0.453以上);AHP计算的V型参数值偏高(x在0.614以上),S型参数值偏低(z在0.088以下);3种方法计算的生活史型划分参数差异明显。由于PCA、AHP均要求性状指标之间相互独立,不能排除性状指标之间的关联,因此基于PCA、AHP的四棱豆生活史型划分结果均出现了偏差,表明性状指标之间的相关性影响了生活史型划分结果。ANP的指标体系为"网状"结构,其控制层、网络层各个指标之间均存在关联。构建ANP的判断矩阵时提取了性状指标的相关矩阵信息,权重配置反映了性状指标之间的相关关系。基于ANP方法对攀援型和矮生型四棱豆生活史型的划分结果分别为V0.517C0.327S0.156和V0.416C0.43S0.154。当性状指标之间的相关不显著时,可采用PCA和AHP法分配权重;当性状指标之间存在显著相关时,采用ANP法进行权重配置更为恰当。综上所述,基于ANP的植物生活史型划分方法解决了性状指标之间相互影响问题,为植物生活史型定量研究提供了新的有效方法。     

生态治理技术评价指标体系

为了对生态治理技术进行更加科学合理的评价,在确定了指标体系构建思路的基础上,根据评价指标的筛选原则,通过对评价指标的理论初选和专家筛选,构建了能够揭示生态治理技术本身属性、相宜性、应用效果、推广潜力等的综合评价指标体系。该指标体系包含目标层和指标层两个层次,目标层为生态治理技术适应效果,指标层分为控制性指标和分类评价指标。控制性指标包含5个一级指标和14个二级指标,适用于所有类型的生态治理技术;分类评价指标为三级指标,共有水土保持技术、荒漠化治理技术、石漠化治理技术和生态恢复技术四个类型的三级指标各29个,针对不同的生态治理技术可以选用合适的三级指标对其进行评价。这样的评价指标体系既可体现区域差异,又可建立公共评价平台,为生态治理技术的评估提供了科学依据和关键技术支撑。     

The Effects of Electronic Cigarette Emissions on Systemic Cotinine Levels,Weight and Postnatal Lung Growth in Neonatal Mice

Background/ObjectiveElectronic cigarette (E-cigarettes) emissions present a potentially new hazard to neonates through inhalation, dermal and oral contact. Exposure to nicotine containing E-cigarettes may cause significant systemic absorption in neonates due to the potential for multi-route exposure. Systemic absorption of nicotine and constituents of E-cigarette emissions may adversely impact weight and lung development in the neonate. To address these questions we exposed neonatal mice to E-cigarette emissions and measured systemic cotinine levels and alveolar lung growth.

Methods/Main Results

Neonatal mice were exposed to E-cigarettes for the first 10 days of life. E-cigarette cartridges contained either 1.8% nicotine in propylene glycol (PG) or PG vehicle alone. Daily weights, plasma and urine cotinine levels and lung growth using the alveolar mean linear intercept (MLI) method were measured at 10 days of life and compared to room air controls. Mice exposed to 1.8% nicotine/PG had a 13.3% decrease in total body weight compared to room air controls. Plasma cotinine levels were found to be elevated in neonatal mice exposed to 1.8% nicotine/PG E-cigarettes (mean 62.34± 3.3 ng/ml). After adjusting for sex and weight, the nicotine exposed mice were found to have modestly impaired lung growth by MLI compared to room air control mice (p<.054 trial 1; p<.006 trial 2). These studies indicate that exposure to E-cigarette emissions during the neonatal period can adversely impact weight gain. In addition exposure to nicotine containing E-cigarettes can cause detectable levels of systemic cotinine, diminished alveolar cell proliferation and a modest impairment in postnatal lung growth.     

Auditory neuropathy: a report on three cases with early onsets and major neonatal illnesses

We report 3 children without any brainstem auditory evoked potential (BAEP) neural component who all retained isolated cochlear microphonic potentials as well as click-evoked otoacoustic emissions. Two of them demonstrated only moderately impaired audiometric thresholds. These features correspond to a peculiar pattern of auditory dysfunction recently coined `auditory neuropathy'. In contrast with the published previous cases of auditory neuropathy presenting with an acquired hearing deficit as children or young adults, all 3 children had a history of major neonatal illness and the auditory neuropathy was already demonstrated in the first months of their lives.     

Expert elicitation and data noise learning for material flow analysis using Bayesian inference

Bayesian inference allows the transparent communication and systematic updating of model uncertainty as new data become available. When applied to material flow analysis (MFA), however, Bayesian inference is undermined by the difficulty of defining proper priors for the MFA parameters and quantifying the noise in the collected data. We start to address these issues by first deriving and implementing an expert elicitation procedure suitable for generating MFA parameter priors. Second, we propose to learn the data noise concurrent with the parametric uncertainty. These methods are demonstrated using a case study on the 2012 US steel flow. Eight experts are interviewed to elicit distributions on steel flow uncertainty from raw materials to intermediate goods. The experts' distributions are combined and weighted according to the expertise demonstrated in response to seeding questions. These aggregated distributions form our model parameters' informative priors. Sensible, weakly informative priors are adopted for learning the data noise. Bayesian inference is then performed to update the parametric and data noise uncertainty given MFA data collected from the United States Geological Survey and the World Steel Association. The results show a reduction in MFA parametric uncertainty when incorporating the collected data. Only a modest reduction in data noise uncertainty was observed using 2012 data; however, greater reductions were achieved when using data from multiple years in the inference. These methods generate transparent MFA and data noise uncertainties learned from data rather than pre-assumed data noise levels, providing a more robust basis for decision-making that affects the system.     

An evaluation of ensign wasp classification (Hymenoptera: Evaniidae) based on molecular data and insights from ribosomal RNA secondary structure

Abstract.  Ensign wasps (Hymenoptera: Evaniidae) are colourful, frequently collected and easily distinguished from other parasitic Hymenoptera. Despite many fascinating biological attributes, this group of insects has been overlooked by ecologists and systematists. An imposing obstacle inhibiting research on these wasps is the current state of their chaotic and potentially flawed classification, which has more than 50% of all described species assigned to the genus Evania – a taxon long suspected of being polyphyletic. The generic classification has recently been redefined on the basis of morphological characters. We tested this reinterpreted classification by analysing sequence data from three genes [28S ribosomal RNA (rRNA), 16S rRNA and cytochrome oxidase I (COI)] under parsimony and Bayesian criteria. For the 28S and 16S rRNAs, we illustrate the predicted secondary structures and provide a series of summary statistics for them; information pertaining to these structures was incorporated into our phylogenetic analyses where appropriate. Phylogenetically, our results indicate that this new generic classification is relatively sound, but that more data are required to understand intergeneric relationships.     

Otoacoustic emissions at different click intensities: invariant and subject-dependent features.

A study of click-evoked otoacoustic emissions (CEOAEs) elicited at stimulation intensities from 35 to >80 dB was carried out by recurrence quantification analysis on signals from both normal and hearing-impaired subjects. In normal subjects, a clear scaling of determinism with increasing stimulation intensity was observed in the click intensity range from 41 to 59 dB. Outside that range and, in particular, above its upper end, subject-dependent features appeared in the form of different maximal levels of determinism. A comparative analysis of responses from hearing-impaired subjects with conductive hearing losses and sensorineural hearing losses suggested that the principal contributor to this behavior is the middle ear and allowed us to discriminate the two pathologies solely on the basis of CEOAEs. These observations are consistent with a simple phenomenological model of the auditory periphery in which different functional modules are sequentially recruited at increasing stimulus intensities, with a consequent rise in CEOAE coherence.     

A comparison of results from parameter estimations of impulse responses of the transient visual system

Parameter estimations of a fourth-order linear model are applied to data from subthreshold measurements of impulse responses of the transient visual system. These impulse responses were obtained experimentally by several subjects, at two different background luminance levels and for different field sizes. The parameter estimations show consistent results over different subjects. For both different background levels and field sizes there are consequent changes in the estimated parameters. On the basis of these changes a proposal is made for a spatiotemporal model of the transient visual system.Interdepartmental Group Retina Models. Participating Groups: IPO Institute for Perception Research, Eindhoven, EE Department, Eindhoven University of Technology     

基于对象特征的山东省丘陵地区多时相遥感土地覆被自动分类

对于基于像元的土地覆被分类来说,植被的分类是难点。使用多时相面向对象分类方法可以较好的解决这个问题。以山东省烟台市丘陵地区为研究区,采用Landsat TM(Landsat Thematic Mapper remotely sensed imagery)、DEM(Digital Elevation Model)、坡度、坡位、坡向等多种数据,利用基于对象特征的多时相分类方法对研究区进行土地覆盖自动分类。首先对影像进行多尺度分割并检验分割结果选取合适的分割尺度,然后分析对象的光谱、纹理、形状特征。根据各类地物的光谱特征、地理相关性、形状、空间分布等特征,明确类别之间的差异。建立决策树使用隶属度函数进行模糊分类,借助支持向量机提高分类精度。研究结果表明,通过使用多时相影像采用面向对象分类方法,相对于传统的基于像素的分类可以明显提高分类精度,尤其是解决了乔灌草的区分问题。     

Formalized reproduction of an expert‐based phytosociological classification: A case study of subalpine tall‐forb vegetation

Abstract. Delimitation of vegetation units in phytosociology is traditionally based on expert knowledge. Applications of expert‐based classifications are often inconsistent because criteria for assigning relevés to vegetation units are seldom given explicitly. Still, there is, e.g. in nature conservation, an increasing need for a consistent application of vegetation classification using computer expert systems for unit identification. We propose a procedure for formalized reproduction of an expert‐based vegetation classification, which is applicable to large phytosociological data sets. This procedure combines Bruelheide's Cocktail method with a similarity‐based assignment of relevés to constancy columns of a vegetation table. As a test of this method we attempt to reproduce the expert‐based phytosociological classification of subalpine tall‐forb vegetation of the Czech Republic which has been made by combination of expert judgement and stepwise numerical classification of 718 relevés by TWINSPAN. Applying the Cocktail method to a geographically stratified data set of 21794 relevés of all Czech vegetation types, we defined groups of species with the statistical tendency of joint occurrences in vegetation. Combinations of 12 of these species groups by logical operators AND, OR and AND NOT yielded formal definitions of 14 of 16 associations which had been accepted in the expert‐based classification. Application of these formal definitions to the original data set of 718 relevés resulted in an assignment of 376 relevés to the associations. This assignment agreed well with the original expert‐based classification. Relevés that remained un‐assigned because they had not met the requirements of any of the formal definitions, were subsequently assigned to the associations by calculating similarity to relevé groups that had already been assigned to the associations. A new index, based on frequency and fidelity, was proposed for calculating similarity. The agreement with the expert‐based classification achieved by the formal definitions was still improved after applying the similarity‐based assignment. Results indicate that the expert‐based classification can be successfully formalized and converted into a computer expert system.     

Structural classification of multi-input nonlinear systems

We present new structural classification and parameter estimation results that are applicable to multi-input nonlinear systems. The mathematical relationships between the self- and cross-(Volterra and Wiener) kernels are derived for a basic two-input nonlinear structure. These results are then used to develop classification methods for more complicated two-input structures. Algorithms for estimating the parameters (linear and nonlinear subsystems) of these structures are also presented.     

Development and prevalidation of a list of structure-activity relationship rules to be used in expert systems for prediction of the skin-sensitising properties of chemicals

The new European Union (EU) chemicals policy, as described in the White Paper entitled Strategy for a Future Chemicals Policy, has identified a need for computer-based tools suitable for predicting the hazardous properties of chemicals. Two sets of structural alerts (fragments of chemical structure) for the prediction of skin sensitisation hazard classification ("R43, may cause sensitisation by skin contact") have been drawn up, based on sensitising chemicals from a regulatory database (containing data for the EU notification of new chemicals). These alerts comprise 15 rules for chemical structures deemed to be sensitising by direct action of the chemicals with cells or proteins within the skin, and three rules for substructures that act indirectly, i.e. requiring chemical or biochemical transformation. The predictivity rates of the rules were found to be good (positive predictivity, 88%; false-positive rate, 1%; specificity, 99%; negative predictivity, 74%; false-negative rate, 80%; sensitivity, 20%). Because of the confidential nature of the regulatory database, the rules are supported by examples of sensitising chemicals taken from the "Allergenliste" now held by the Federal Institute for Risk Assessment (BfR) and the DEREK for Windows expert system. The rules were prevalidated against data not used for their development. As a result of the prevalidation study, it is proposed that the two sets of structural alerts should be taken forward for formal validation, with a view to incorporating them into regulatory guidelines.     

Sleep classification in infants based on artificial neural networks.

The study reports on the possibility of classifying sleep stages in infants using an artificial neural network. The polygraphic data from 4 babies aged 6 weeks, 6 months and 1 year recorded over 8 hours were available for classification. From each baby 22 signals were recorded, digitized and stored on an optical disc. Subsets of these signals and additional calculated parameters were used to obtain data vectors, each of which represents an interval of 30 sec. For classification, two types of neural networks were used, a Multilayer Perceptron and a Learning Vector Quantizer. The teaching input for both networks was provided by a human expert. For the 6 sleep classes in babies aged 6 months, a 65% to 80% rate of correct classification (4 babies) was obtained for the testing data not previously seen.