Removing ECG contamination from EMG recordings: a comparison of ICA-based and other filtering procedures

Trunk muscle electromyography (EMG) is often contaminated by the electrocardiogram (ECG), which hampers data analysis and potentially yields misinterpretations. We propose the use of independent component analysis (ICA) for removing ECG contamination and compared it with other procedures previously developed to decontaminate EMG. To mimic realistic contamination while having uncontaminated reference signals, we employed EMG recordings from peripheral muscles with different activation patterns and superimposed distinct ECG signals that were recorded during rest at conventional locations for trunk muscle EMG. ICA decomposition was performed with and without a separately collected ECG signal as part of the data set and contaminated ICA modes representing ECG were identified automatically. Root mean squared relative errors and correlations between the linear envelopes of uncontaminated and contaminated EMG were calculated to assess filtering effects on EMG amplitude. Changes in spectral content were quantified via mean power frequencies. ICA-based filtering largely preserved the EMG's spectral content. Performance on amplitude measures was especially successful when a separate ECG recording was included. That is, the ICA-based filtering can produce excellent results when EMG and ECG are indeed statistically independent and when mode selection is flexibly adjusted to the data set under study.     

Effects of psychophysiological stress on trapezius muscles blood flow and electromyography during static load

Mental stress was induced by the Stroop colour word task (CW task) and the effects on the micro-circulation and electromyography (EMG) in the upper portion of the trapezius muscle were studied during a series of fatiguing, standardized static contractions. A lowered blood flow of the skin recorded continuously by laser-Doppler flowmetry (LDF) was used as a stress indicator in addition to an elevated heart rate. Muscle blood flow was recorded continuously by LDF using a single optical fibre placed inside the muscle, and related to surface EMG. A group of 20 healthy women of different ages was examined. Recordings were made during a 50-min period in the following sequence: a 10-min series of alternating 1-min periods of rest and stepwise increased contraction induced by keeping the arms straight and elevated at 30, 60, 90 and 135° with a 1-kg load carried in each hand; a 10-min recovery period without load; a repeated contraction series with simultaneous performance of the CW task; a second 10-min recovery period, and a second contraction series without CW task. Signal processing was done on line by computer. The LDF and root mean square (rms)-EMG values were calculated, as well as the EMG mean power frequency (MPF) for fatigue. The CW-task added to the contraction series caused an increase in the heart rate accompanied by a decrease in the blood flow to the skin and a 30% increase in the blood flow in the exercising muscle. Both returned to normal during the subsequent recovery period and showed normal levels during the final contraction series without CW. The rms-EMG showed a 20% increase that persisted during the final contraction series performed without CW. There was no influence on MPF. This CW has previously been shown to evoke an increased secretion of adrenaline from the adrenal medullae to the blood. The increased blood flow in the exercising muscle would therefore appear to have been caused by -adrenoceptor vasodilatation, and the fall in the blood flow in the skin by -adrenoceptor vasoconstriction. The findings may have implications for work situations characterized by repetitive static loads to the shoulder muscles and psychological stress.     

水培经济植物对污水中磷的吸收利用及去除效果

对13种经济植物在污水水培条件下净化污水中磷的能力进行了研究。结果表明,黑麦草(Lolium multiflorum)、水芹(Oenanthe stolonifera)、莴苣(Lactuca sativavar.angustana)、酸模(Poly-gonum iapathifolium)、生菜(Lactuca sativa)、小葱(Allium ascalonicum)、五月慢青菜(Brassica chinen-sis)等品种具有较高的净化能力。在4个半月的水培中,TP的去除量分别达到10.27、10.35、6.5~6.896、.91、5.72、5.46和6.19 g.m-2;TP的去除率分别达到94.5%、95.2%、93.6%~99.3%、99.6%、99.5%、95%和89.2%。植物吸收作用是最主要的污水磷去除机制,沉淀在污水磷净化中的作用较小。污水中磷的去除与植物的生长期密切相关。黑麦草、水芹等7种植物适宜作为苏南地区冬季化粪池污水水培植物。     

信号分子在生物脱氮中的作用及检测方法

生物脱氮是由微生物主导的地球氮循环中的重要环节之一,主要包括硝化、反硝化和厌氧氨氧化(anaerobic ammonium oxidation,anammox)等过程。在微生物联合作用下,污水中的有机氮及氨氮经一系列作用转化为氮气,这种经济高效、环境友好的处理工艺在世界范围内得到广泛应用。群体感应(quorum sensing,QS)以信号分子为媒介通过改变菌群密度和周围环境变化来调节微生物的各种行为。大量的研究已证实调控QS信号分子在生物脱氮中具有应用潜力。本文介绍了各种信号分子类型,从基因组学、实际应用等方面综述了各类信号分子以及检测方法,同时针对酰基高丝氨酸内酯(acyl homoserine lactones,AHLs)类信号分子在生物脱氮中的作用进行详细介绍。然而不足之处在于信号分子研究只是停留在实验室阶段,仅仅研究了单一信号分子对生物脱氮的影响。未来可将信号分子应用于实际污水,研究多种信号分子共同作用以及多种微生物之间的QS现象。     

Angiosperm DNA contamination by endophytic fungi: Detection and methods of avoidance

PCR primers with broad applicability are useful in many molecular-based studies; however, their universality can compromise results when DNA contaminants also are amplified. Eighty-one templates ofDahlia (Asteraceae), primarily extracted from native Mexican populations, were tested for the presence of fungal contaminants; out of these, almost 1 in 7 templates (13.6%) was contaminated. In a second survey across 12 angiosperm families using material collected in Illinois, fungal DNA contaminated over 60% of the templates analyzed. Endophytic fungi often are symptomless symbionts living within the above-ground tissues of their angiosperm hosts and are not affected by surface sterilization techniques. Recent studies have revealed their widespread occurrence and broad host range. We also present field strategies for obtaining plant material to reduce the possibility of collecting infected leaves and a simple screening test for detecting fungal DNA in angiosperm templates.     

Surface EMG amplitude and frequency dependence on exerted force for the upper trapezius muscle: a comparison between right and left sides

Surface electromyographic (EMG) amplitude and mean power frequency (MPF) were used to study the isometric muscular activity of the right versus the left upper trapezius muscles in 14 healthy right-handed women. The EMG activity was recorded simultaneously with force signals during a 10-15 s gradually increasing exertion of force, up to maximal force. Only one side at a time was tested. On both sides there was a significant increase in EMG amplitude (microV) during the gradually increasing force from 0% to 100% maximal voluntary contraction (MVC). The right trapezius muscle showed significantly less steep slopes for regression of EMG amplitude versus force at low force levels (0%-40% MVC) compared intra-individually with high force levels (60%-100% MVC). This was not found for the left trapezius muscle. At 40% MVC a significantly lower MPF value was found for the right trapezius muscle intra-individually compared with the left. An increase in MPF between 5% and 40% MVC was statistically significant when both sides were included in the test. The differences in EMG activity between the two sides at low force levels could be due to more slow-twitch (type I fibres) motor unit activity in the right trapezius muscles. It is suggested that this is related to right-handed activity.     

不同麻醉方式对老年冠心病患者围术期血流动力学及ECG的影响

目的：探讨对择期腹部手术的老年冠心病患者心脏血流动力学及心脏电活动影响较小的麻醉方式。方法：133例择期腹腔手术的老年冠心病患者随机分为硬膜外麻醉组（EA）,全麻组（GA）和腰-硬联合麻醉组（CSEA）。术中连续监测,分时段记录平均动脉压（MAP）、心率（HR）、血氧饱和度（SaO2）及异常心电图,比较3组组间及组内差异。结果：麻醉后15 min和麻醉后30 min,GA组的SaO2明显高于EA组（P〈0.05）。麻醉后15min、30 min和60 min CSEA组MAP值比EA组明显升高（P〈0.05）;麻醉后30 min,CSEA组的HR比EA组明显升高（P〈0.05）;麻醉后15 min和30 min,CSEA组的SaO2比EA组明显升高（P〈0.05）。组内比较,EA组麻醉后15min、30 min、60 min,MAP、HR、SaO2三个指标均比麻醉前明显降低（P〈0.05）,GA组和CSEA组前后比较差异不明显（P〉0.05）。异常ECG,组间比较,GA组和CSEA组ST-T改变发生率在麻醉后15 min、30 min、60 min、术毕时均明显低于EA组（P〈0.05,P〈0.01）,GA组和CSEA组心律失常发生率在麻醉后15 min、30 min、60 min均明显低于EA组（P〈0.05,P〈0.01）;组内比较,GA组和CSEA组的ST-T改变和心律失常发生率在麻醉后15 min、30min、60 min、术毕时均明显低于麻醉前（P〈0.05,P〈0.01）。结论：老年冠心病患者腹腔手术时全麻和腰-硬联合麻醉术中血流动力学较稳定,心电异常发生率较小。     

Accurate and efficient estimation of benthic populations: A comparison between removal estimation and conventional sampling techniques

A Circular Depletion Sampler (CDS) was designed to allow the removal of consecutive subsamples from a sample area, while minimizing immigration and emigration. Equal sampling effort was expended during each removal period to permit estimation of both the probability of capture, and the number of individuals not captured from a sample area. Average probabilities of capture from 270 CDS samples ranged from 0.19 per minute for Antocha (Tipulidae) to 0.96 for Paratendipes (Chiroal (3 removal periods), Surber, and kick-net methods. Removal population estimates were consistently higher and less variable than those of the other methods. Estimates of diversity from samples taken with conventional methods were biased by differences in catchability, and by emigration. Separation of benthos from detritus took about twice as long per unit sample area for Surber and kick-net methods, although sampling time per unit area was nearly equal for all three methods. Removal estimates using only the first two catches were comparable to estimates based on three catches, indicating a further possible increase in efficiency.     

随机抽样对蛋白质相互作用网络度分布的影响

蛋白质相互作用(PPI)网络,是目前系统研究蛋白质层面细胞活动的重要工具,PPI网络的度分布是研究复杂网络性质的重要物理量。随着蛋白质相互作用数据量不断的增加,其数据的可靠性是否会对PPI网络的度分布造成影响,并不确定。本文对四种模式生物的PPI网络数据,按照5%的增长比率,随机删除PPI网络的边,来检验随机抽样对PPI网络度分布的影响。结果表明,各种实验数据的误差不会对真实PPI网络的度分布造成干扰,且在目前描述网络度分布的五种函数中,广延指数函数拟合程度最优。     

Effects of frontal ganglion removal and starvation on activity and distribution of six gut enzymes in Locusta

A study has been made on the effects of frontal ganglion removal and starvation on the activities and distribution of α- and β-glucosidase, α- and β-galactosidase, trehalase, and ‘trypsin’ in various regions of the alimentary canal of adult locusts. Both treatments resulted in a reduction in the amount of enzyme activity. In addition, the distribution of enzyme activity was changed by comparison with the operated control insects; the foregut of starved and operated animals showing a smaller proportion of the overall gut enzyme activity. The results are discussed in relation to the control of enzyme secretion.     

Effects of solution environment on mammalian cell fermentation broth properties: Enhanced impurity removal and clarification performance

The processing of recombinant proteins from high cell density, high product titer cell cultures containing mammalian cells is commonly performed using tangential flow microfiltration (MF). However, the increased cellular debris present in these complex feed streams can prematurely foul the membrane, adversely impacting MF capacity and throughput. In addition, high cell density cell culture streams introduce elevated levels of process‐related impurities, which increase the burden on subsequent purification operations to remove these complex media components and impurities. To address this challenge, an evaluation of mammalian cell culture broth buffer properties was examined to determine if enhanced impurity removal and clarification performance could be achieved. A framework is presented here for establishing optimized mammalian cell culture buffer conditions, involving trade‐offs between product recovery and purification and improved clarification at manufacturing‐scale production. A reduction in cell culture broth pH to 4.7–5.0 induced flocculation and impurity precipitation which increased the average feed particle‐size. These conditions led to enhanced impurity removal and improved MF throughput and filter capacity for several mammalian systems. Feed conditions were further optimized by controlling ionic composition along with pH to improve product recovery from high cell density/high product titer cell cultures. Biotechnol. Bioeng. 2011; 108:50–58. © 2010 Wiley Periodicals, Inc.     

Effects of removal of riparian vegetation on algae and heterotrophs in a Mediterranean stream

The effect of removal of a riparian strip on aquaticautotrophic (algae) and heterotrophic (bacteria,macroinvertebrates) organisms was monitored in aMediterranean stream during the canopy growing period.Community composition, biomass and metabolicactivities were compared with those recorded during apre-riparian removal period and in a forested stretchdownstream. Higher irradiance was associated with Cladophora increase in the logged section. Algalbiomass increased up to ten times, and productivitywas up to four times higher than in the pre-removalperiod and the forested section. Bacterialcommunities showed higher ectoenzymatic activities(-glucosidase, -xylosidase) in thelogged section than in forested conditions. Moreoverthe coincidence between the maxima of-glucosidase and chlorophyll-a suggeststhat bacterial activity was enhanced by the higheravailability of high-quality algal material. Themacroinvertebrate community had higher density andbiomass in the logged section than in the forestedsection and in the pre-removal period. Scrapers andfilterers become dominant after riparian removal,while shredders, predators and collectors did not showsignificant changes either between sites or periods.Responses of environmental variables and bioticcommunities indicate that the changes occurring in thestream due to riparian removal could be consideredbottom-up controlled, as increased illumination wasthe main mechanism responsible.     

模拟增温和功能群去除对岷江冷杉幼苗存活和生长的影响

通过模拟增温和功能群去除试验,研究不同功能群的草本植物在岷江冷杉幼苗更新定植过程的作用,分析其在温度升高条件下生理指标的变化.结果表明:增温提高了岷江冷杉幼苗的存活率和植物体内非结构性碳水化合物含量,但抑制了幼苗的生长和根冠比.岷江冷杉幼苗的非结构性碳水化合物含量,尤其是可溶性糖含量与存活率呈显著正相关.不增温处理中,草本植物降低了幼苗的存活率,促进幼苗的株高生长和地上生物量积累,禾本科植物和杂类草抑制了幼苗根系生长和地下生物量的积累;增温处理中,杂类草的存在提高了幼苗的存活率,莎草科则显著抑制了幼苗根系生长和地下生物量的积累,禾本科植物和杂类草抑制了幼苗的高生长和地上生物量积累.模拟增温提高了林线树种岷江冷杉幼苗的存活率,但使其面临来自草本植物更剧烈的竞争,抑制其生长.     

优势种去除对崇明东滩盐沼湿地生态系统的影响

盐沼生态系统环境梯度明显,物种组成较简单,是研究生物多样性与生态系统功能关系的理想对象。本研究以崇明东滩盐沼湿地为研究区域,研究优势种去除对植物群落结构以及底栖动物群落的影响。结果表明:(1)去除处理仅对植物群落分株密度有极显著效应(P0.01)。去除组和对照组物种组成差异随时间增加而减小,处理效应逐渐减弱。(2)去除组底栖动物密度均低于对照组,但差异不显著。(3)盐沼植物群落特征与底栖动物群落有密切关系,植物密度、冠层高度与底栖动物密度相关性极显著。去除优势种后,植物群落分株密度升高,群落内剩余物种占比有所上升,次优势种对群落的补偿效应具有较大贡献;而底栖动物群落密度下降,其生物量和多样性指数的变化趋势与密度并不一致。上述结果表明生物多样性变化影响了盐沼湿地生态系统植物群落和底栖动物群落结构,进而可能影响物质循环和能量流动过程。     

间伐和林下植被剔除对毛竹林土壤氮矿化速率及其温度敏感性的影响

选择中亚热带毛竹人工林为研究对象,利用野外原位和室内培养相结合的方法,探讨不同间伐强度(25%间伐、50%间伐)和林下植被剔除对土壤氮矿化速率及其温度敏感性的影响。结果表明,25%间伐显著增加土壤氨化速率(P0.01),但降低硝化速率(P0.01);50%间伐显著增加土壤硝化速率(P0.01),而林下植被剔除显著降低土壤硝化速率(P0.01)。相关分析的结果表明,土壤氨化速率与有机碳(SOC)、全氮(TN)及全磷(TP)含量呈显著负相关关系;硝化速率与SOC、含水量(SWC)呈显著正相关关系,与铵态氮(NH~+_4-N)含量呈显著负相关关系。随着温度的升高,不同处理下的氨化速率均显著增加(P0.01),而硝化速率显著降低(P0.01)。25%间伐显著降低土壤净氮矿化和氨化过程的Q_(10)值,对硝化过程的Q_(10)值影响不显著;50%间伐对氨化和硝化过程的Q_(10)值影响均不显著;林下植被剔除对氨化过程的Q_(10)值影响不显著,但显著增加硝化过程的Q_(10)值。不同处理下的土壤氮矿化过程的Q_(10)值介于1.17—1.36之间。25%间伐和林下植被保留有利于毛竹林土壤氮素的供给。     

凋落物和土壤覆盖对动物取食和搬运辽东栎种子的影响

在六盘山区的华北落叶松人工林,研究了清除凋落物、凋落物覆盖和土壤覆盖(以不清除凋落物直接将种子投放于森林地表为对照)等处理对动物取食和搬运辽东栎种子的影响.结果表明:种子释放3d后,凋落物和土壤覆盖处理种子均具有较高的留存率(分别为10.7％和7.0％);释放14 d后,土壤覆盖处理种子的留存率仍最高(0.7％),但凋落物覆盖处理种子的留存率为0.凋落物和土壤覆盖处理种子的就地取食率很高(分别为45.9％和41.5％);清除凋落物处理种子的就地取食率最低(27.0％),但其被搬运后的取食率最高(49.8％);凋落物覆盖、清除凋落物和土壤覆盖处理种子被动物搬运后的埋藏率均显著高于对照(P＜0.01).种子被动物搬运后集中分布于5 m以内,尤其在＜1 m和l～2m两个距离组的分布频率更高;种子被搬运后取食的平均距离大干埋藏的平均距离,以土壤覆盖和凋落物覆盖处理最大,分别为2.38 m±0.55 m和1.44m±0.26 m.     

Effects of ammonium ion removal on growth and MAb production of hybridoma cells

Production of monoclonal antibody against hepatitis B surface antigen was carried out by perfusion culture coupled with a selective removal system for ammonium ion. The removal system is composed of three sub-systems namely, cell separation by cross-flow ceramic filter, dialysis by hollow fiber module and ion-exchange by zeolite A-3 packed bed column. The ammonium ion concentration in the culture broth was effectively maintained below the inhibitory level, and the viable cell density reached 2.5×10⁷ cells ml^–1 which was three times that of conventional perfusion cultures. The monoclonal antibody accumulated to a concentration as high as 26.3×10⁵ mIU^–1. This is already almost half of the amount producedin vivo. The numerical investigation of the ammonium ion removal system showed the possibility to improve much more the performance of this perfusion cultivation system.     

林下植被抚育对樟人工林生态系统碳储量的影响

以亚热带东部地区48年生樟(Cinnamomum camphora)人工林为研究对象, 探讨不同林下植被处理方式对植被和土壤碳储量的影响。研究结果表明: 1)林下植被抚育增加了植被的碳储量, 增幅为48.87%, 平均每年比未抚育林分增加了0.62 t·hm^-2; 2)林下植被抚育降低了土壤有机碳含量, 降低幅度介于4.79%-34.13%之间, 其中0-10 cm、10-20 cm土层比未抚育林分分别降低了10.16 g·kg^-1和8.58 g·kg^-1, 差异达到显著水平(p < 0.05); 3)林下植被抚育降低了森林土壤碳储量, 降低幅度介于1.98%-43.45%之间, 其中0-10 cm和10-20 cm土层分别降低了15.39 t·hm^-2和11.58 t·hm^-2, 差异达到极显著水平(p < 0.01)和显著水平(p < 0.05); 4)林下植被抚育降低了森林生态系统总碳储量, 降低幅度为4.27%, 但差异不显著。因此, 林下植被抚育虽有利于植被碳储量的积累, 但降低了土壤有机碳含量和储量。     

Effects of temporary calf removal and eCG on pregnancy rates to timed-insemination in progesterone-treated postpartum Nellore cows

The objective was to evaluate the effects of temporary calf removal (TCR), eCG administration, or both, in a progesterone-based protocol. Suckled Nellore cows (40-80 d postpartum, n=443) with body condition scores from 2.0 to 3.5 (5-point scale) on three farms were all given a synchronizing protocol (PEPE). At the start (designated Day 0), cows were given an intravaginal device (1.0 g of progesterone) and 2.5mg of estradiol benzoate (EB) im. On Day 8, the device was removed and cows were given PGF(2 alpha) (150 microg of D-cloprostenol im), followed in 24h by 1.0mg EB im, and 30-36 h thereafter, fixed-time AI. The design was a 2 x 2 factorial; main effects were TCR (54-60 h; from device removal to FTAI) and eCG treatment (300 IU im, concurrent with PGF(2 alpha)). Transrectal ultrasonography was done on Days -10 and 0 to detect anestrus (absence of a CL at both examinations) and approximately 30 d after FTAI (pregnancy diagnosis). Data were analyzed by logistic regression. The following variables did not significantly affect pregnancy rates: farm, postpartum interval, cyclicity, inseminators, and semen (sire). Overall, 77% of the cows were deemed anestrus. Pregnancy rates were similar (P>0.05) among treatment groups: Control (54/108=50.0%), TCR (44/106=41.5%), eCG (63/116=54.3%), and TCR+eCG (49/113=43.4%). Pregnancy rate was higher in multiparous than primiparous cows (186/360, 51.7% vs. 24/83, 28.9%, P<0.01), but was not significantly affected by cyclicity status or body condition score. In conclusion, temporary calf removal, eCG, or both, did not significantly increase pregnancy rate to timed-insemination in a progesterone-based synchronization protocol in postpartum Nellore cows with acceptable body condition.     

Effects of large-scale removal of coyotes on pronghorn and mule deer productivity and abundance

We tested the hypothesis that predation by coyotes (Canis latrans) impacts pronghorn (Antilocapra americana) and mule deer (Odocoileus hemionus) populations. We did so by examining the effects of coyote removal on pronghorn and mule deer populations within 12 large areas (>10,500 km²) located in Wyoming and Utah during 2007 and 2008. Pronghorn productivity (fawn to adult female ratio) and abundance were positively correlated with the number of coyotes removed and removal effort (hours spent hunting coyotes from aircraft) although the correlation between pronghorn productivity and removal effort was not statistically significant (P = 0.08). Mule deer productivity and abundance were not correlated with either the number of coyotes removed or removal effort. Coyote removal conducted during the winter and spring provided greater benefit than removals conducted during the prior fall or summer. Our results suggest that coyote removal conducted over large areas increases fawn survival and abundance of pronghorn but not mule deer. © 2011 The Wildlife Society.