Analysis of Magneto-Optical Hysteresis Loops of Amorphous and Surface-Crystalline Fe-Based Ribbons

Three Fe-based ribbon-type samples prepared by a conventional planar flow casting process are studied from the viewpoint of the amorphous Fe₈₀Si₄B₁₆ and partially surface crystallized Fe₈₀Si₁₀B₁₀, and Fe_80.5Nb_6.9B_12.6, microstructures. Surface magnetic properties are investigated by magneto-optical Kerr microscopy, allowing the measurement of a local hysteresis loop from a selected area on the ribbon surface, and simultaneously, a domain structure corresponding to a definite point at the loop. For an amorphous sample, the changes in the slopes of hysteresis loops are related either to the size of the selected surface area, from which the loop is measured, or to the type, width, and movement of magnetic domains through this area. In the first case, the resizing of the area simulates an effect of changing the diameter of the incident laser beam on the magneto-optical properties of the ribbon. In the latter case, the observed wide-curved and fingerprint domains are responsible for markedly different shapes of the hysteresis loops at lower magnetic fields. If the surface is crystallized, the magnetic properties are more homogenous, showing typical one-jump magnetization reversal with less dependence on the size of the surface area. The magneto-optical experiments are completed by transmission electron microscopy and magnetic force microscopy.     

Synthesis and Characterization of Holmium-Doped Iron Oxide Nanoparticles

Rare earth atoms exhibit several interesting properties, for example, large magnetic moments and luminescence. Introducing these atoms into a different matrix can lead to a material that shows multiple interesting effects. Holmium atoms were incorporated into an iron oxide nanoparticle and the concentration of the dopant atom was changed in order to determine its influence on the host crystal. Its magnetic and magneto-optical properties were investigated by vibrating sample magnetometry and Faraday rotation measurements. The luminescent characteristics of the material, in solution and incorporated in a polymer thin film, were probed by fluorescence experiments.     

Enhanced Magneto-Optic Properties in Sputtered Bi- Containing Ferrite Garnet Thin Films Fabricated Using Oxygen Plasma Treatment and Metal Oxide Protective Layers

Magneto-optic (MO) imaging and sensing are at present the most developed practical applications of thin-film MO garnet materials. However, in order to improve sensitivity for a range of established and forward-looking applications, the technology and component-related advances are still necessary. These improvements are expected to originate from new material system development. We propose a set of technological modifications for the RF-magnetron sputtering deposition and crystallization annealing of magneto-optic bismuth-substituted iron-garnet films and investigate the improved material properties. Results show that standard crystallization annealing for the as-deposited ultrathin (sputtered 10 nm thick, amorphous phase) films resulted in more than a factor of two loss in the magneto-optical activity of the films in the visible spectral region, compared to the liquid-phase grown epitaxial films. Results also show that an additional 10 nm-thick metal-oxide (Bi₂O₃) protective layer above the amorphous film results in ~2.7 times increase in the magneto-optical quality of crystallized iron-garnet films. On the other hand, the effects of post-deposition oxygen (O₂) plasma treatment on the magneto-optical (MO) properties of Bismuth substituted iron garnet thin film materials are investigated. Results show that in the visible part of the electromagnetic spectrum (at 532 nm), the O₂ treated (up to 3 min) garnet films retain higher specific Faraday rotation and figures of merit compared to non-treated garnet films.     

Raman spectra of single cell from gastrointestinal cancer patients

AIM: To explore the difference between cancer cells and normal cells,we investigated the Raman spectra of single cells from gastrointestinal cancer patients. METHODS: All samples were obtained from 30 diagnosed as gastrointestinal cancer patients. The flesh tumor specimen is located in the center of tumor tissue, while the normal ones were 5 cm away from the outside tumor section. The imprint was put under the microscope and a single cell was chosen for Raman measurement. All spectra were collected at confocal Raman micro-spectroscopy (British Renishaw) with NIR 780 nm laser. RESULTS: We measured the Raman spectra of several cells from gastrointestinal cancer patients. The result shows that there exists the strong line at 1 002 /cm with less half-width assigned to the phenylalanine in several cells. The Raman lines of white cell were lower and less, while those of red cell were not only higher in intensity and more abundant, but also had a particular C-N breathing stretching band of pyrrole ring at 1 620-1 540 /cm. The line at 1 084 /cm assigned to phosphate backbone of DNA became obviously weaker in cancer cell. The Raman spectra of stomach cancer cells were similar to those of normal cells, but the Raman intensity of cancer cells was much lower than that of normal cells, and even some lines disappear. The lines of enteric cancer cells became weaker than spectra above and many lines disappeared, and the cancer cells in different position had different fluorescence intensity. CONCLUSION: The Raman spectra of several cells from cancer patients show that the structural changes of cancer cells happen and many bonds rupture so that the biological function of cells are lost.The results indicate that Raman spectra can offer the experiment basis for the cancer diagnosis and treatment.     

Size Effects in Optical and Magneto-Optical Response of Opal-Cobalt Heterostructures

Search for new types of efficient magnetoplasmonic structures that combine high transparency with strong magneto-optical (MO) activity is an actual problem. Here, we demonstrate that composite heterostructures based on thin perfectly-arranged opal films and a perforated cobalt nanolayer meet these requirements. Anomalous transmission appears due to periodic perforation of Co consistent with the regular set of voids between opal spheres, while resonantly enhanced MO response involves the effects of surface plasmon-polariton (SPP) excitation at opal/Co interface or those associated with photonic band gap (PBG) in opal photonic crrystals. We observed the enhancement of the MO effect of up to 0.6% in the spectral vicinity of the SPP excitation, and several times less strong effect close to the PBG, while the combined appearance of PBG and SPP decreases the resultant MO response. Observed resonant magneto-optical properties of opal/Co heterostructures show that they can be treated as functional self-assembled magnetoplasmonic crystals with resonantly enhanced and controllable MO effect.     

Effect of chromosomal proteins extractable with low concentrations of NaCl on chromatin structure of resting and proliferating cells.

When quiescent WI-38 cells are stimulated to proliferate by nutritional changes, the chromatin of stimulated cells shows an increased ellipticity in circular dichroism spectra and an increased ability to bind ethidium bromide. The differences between the chromatins of quiescent and stimulated cells are abolished if both chromatins are treated with 0.25 M NaCl. However, when salt-treated chromatins are reconstituted by dialysis agains 10 mM Tris-HCl, the difference in circular dichroism spectra and ethidium bromide binding re-appear. Furthermore, addition of the 0.25 M NaCl extract from chromatin of stimulated cells to chromatin of quiescent cells causes an increased ellipticity in circular dichroism spectra similar to that of stimulated chromatin. Since only proteins (mostly nonhistones) are detectable in the 0.25 M NaCl extract, these results strongly suggest that the chromosomal proteins extractable with low concentrations of salt are responsible for the functional and structural changes occurring in chromatin of WI-38 cells stimulated to proliferate.     

Solid-State Synthesis of Polyaniline/Single-Walled Carbon Nanotubes: A Comparative Study with Polyaniline/Multi-Walled Carbon Nanotubes

The polyaniline/single-walled carbon nanotubes (PANI/SWNTs) composites with a content of SWNTs varying from 8 wt% to 32 wt% were synthesized using a solid-state synthesis method. The structure and morphology of the samples were characterized by fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical performances of the composites were investigated by galvanostatic charge–discharge and cycling stability measurements. The structure and properties of PANI/SWNTs were compared with those of PANI/multi-walled carbon nanotubes (PANI/MWNTs) prepared under the same polymerization conditions. The results from FTIR and UV-vis spectra showed that the composites with SWNTs displayed a higher oxidation and doping degree than pure PANI, which is similar to that of PANI/MWNTs. The morphological studies revealed that PANI/SWNTs did not display any rod-like and granular-like features, which appeared in PANI/MWNTs. The galvanostatic charge–discharge measurements indicated that the specific capacitance of PANI/SWNTs is not higher than that of PANI/MWNTs, but the PANI/SWNTs exhibited higher cycling stability and more stable electrochemical behavior in neutral and alkaline electrolytes than PANI/MWNTs.     

A Functional Examination of Hapten-Binding Derivatives from a Murine Myeloma Protein with Immunoglobulin Features

Various enzymatic derivatives of the murine myeloma protein IgA(MOPC-315) were subjected to hapten-binding quantitation and circular dichroic analysis in an attempt to ascertain the structural localization and functional definition of the immunoglobulin active site. The extrinsic Cotton effects observed with near saturation of the active site of the derivatives using epsilon-Dnp-L-lysine were qualitatively and quantitatively identical when normalized with respect to their macromolecular content of Dnp-binding sites; ellipticity maxima of 378 and 438 nm and an ellipticity minimum of 325 nm were recorded. Fluorescence quenching data confirmed the molecular nature of the derivation products of IgA(MOPC-315) but also introduced disparity with respect to binding kinetics, i.e., K values of 2.31 x 10(6), 6.62 x 10(6), and 2.06 x 10(7) M(-1) were determined for IgA(MOPC-315), Fab'(MOPC-315), and Fv(MOPC-315), respectively. We speculate that the results can be explained by possible modulating effects on haptenbinding contributed by novel conformations introduced through proteolysis.     

Comparison of the Values of Solar Cell Contact Resistivity Measured with the Transmission Line Method (TLM) and the Potential Difference (PD)

This work presents a comparison of values of the contact resistivity of silicon solar cells obtained using the following methods: the transmission line model method (TLM) and the potential difference method (PD). Investigations were performed with two independent scientific units. The samples were manufactured with silver front electrodes. The co-firing process was performed in an infrared belt furnace in a temperature range of 840 to 960 °C. The electrical properties of a batch of solar cells fabricated in two cycles were investigated. This work focuses on the different metallisation temperatures of co-firing solar cells and measurements were carried out using the methods mentioned. In the TLM and PD methods, the same calculation formulae were used. Moreover, solar cell parameters measured with these methods had the same, similar, or sometimes different but strongly correlated values. Based on an analysis of the selected databases, this article diagnoses the recent and current state of knowledge regarding the employment of the TLM and PD methods and the available hardware base. These methods are of interest to various research centres, groups of specialists dealing with the optimisation of the electrical properties of silicon photovoltaic cells, and designers of measuring instruments.     

心动周期信号功率谱超低频带的生理意义

用比较分带动态谱（ＣＢＲＳ）分析技术,比较物理或药物试验前后心动周期信号（ＨＰＳ）的分带动态谱,以确定ＨＰＳ超低频段（ＵＬＦ）的生理意义。由ＣＭ５导联获取体表心电信号（ＥＣＳ）,采样频率３００Ｈｚ,采样１０ｍｉｎ,以保证有５１２个以上的心动周期（ＨＰ）存在。从ＥＣＳ提取ＲＲ间期形成ＲＲ数字时间序列,称为心动周期信号［ＨＰＳ（ｎ）］,每次移动１６个ＨＰ作２５６个心动周期序列ＨＰＳ（ｎ）的加窗傅立叶变换。将功率谱分三带（ＵＬＦ：０．００３～０．０４Ｈｚ;低频带,ＬＦ：０．０４～０．１４Ｈｚ;高频带,ＨＦ：０．１４～０．５Ｈｚ）,形成三分带自归一（或自适应）动态谱,在统一标度下形成物理或药物试验前后的ＣＢＲＳ。计算总功率（ＴＰＶ）,每带的绝对功率（ＡＰＵ、ＡＰＬ、ＡＰＨ）,每带的相对功率（ＲＰＵ、ＲＰＬ、ＲＰＨ）,ＵＬＦ和ＬＦ与ＨＦ带功率之比（ＲＵＨ、ＲＬＨ）。结果：在ＣＢＲＳ中,ＬＦ带的右部的变化趋势同ＨＦ带,ＬＦ带的左部的变化趋势同ＵＬＦ带。ＲＰＵ与ＲＵＨ的变化趋势同于（同符号）平均心率（ＭＨＲ）,ＲＰＨ的变化趋势反于（反符号）ＭＨＲ。结论：①ＨＰＳ谱的ＵＬＦ带反映交感神经系统的活动;②ＬＦ带是混合带或过渡带?     

Circular dichroism spectra of short,fixed-nucleus alanine helices

Very short alanine peptide helices can be studied in a fixed-nucleus, helix-forming system [Siedlicka, M., Goch, G., Ejchart, A., Sticht, H. & Bierzynski, A. (1999) Proc. Natl. Acad. Sci. USA 96, 903-908]. In a 12-residue sequence taken from an EF-hand protein, the four C-terminal peptide units become helical when the peptide binds La(3+), and somewhat longer helices may be made by adding alanine residues at the C terminus. The helices studied here contain 4, 8, or 11 peptide units. Surprisingly, these short fixed-nucleus helices remain almost fully helical from 4 to 65 degrees C, according to circular dichroism results reported here, and in agreement with titration calorimetry results reported recently. These peptides are used here to define the circular dichroism properties of short helices, which are needed for accurate measurement of helix propensities. Two striking properties are: (i) the temperature coefficient of mean peptide ellipticity depends strongly on helix length; and (ii) the intensity of the signal decreases much less rapidly with helix length, for very short helices, than supposed in the past. The circular dichroism spectra of the short helices are compared with new theoretical calculations, based on the experimentally determined direction of the NV(1) transition moment.     

Terahertz Photoconductivity Spectra of Electrodeposited Thin Bi Films

Electron dynamics in the polycrystalline bismuth films were investigated by measuring emitted terahertz (THz) radiation pulses after their photoexcitation by tunable wavelength femtosecond duration optical pulses. Bi films were grown on metallic Au, Pt, and Ag substrates by the electrodeposition method with the Triton X-100 electrolyte additive, which allowed us to obtain more uniform films with consistent grain sizes on any substrate. It was shown that THz pulses are generated due to the spatial separation of photoexcited electrons and holes diffusing from the illuminated surface at different rates. The THz photoconductivity spectra analysis has led to a conclusion that the thermalization of more mobile carriers (electrons) is dominated by the carrier–carrier scattering rather than by their interaction with the lattice.     

Phasic changes in upper airway impedance

To identify within breath variations in the mechanical properties of the isolated upper airway, we examined changes in impedance spectra over the course of the respiratory cycle. Changes were evaluated with a modified forced oscillation technique applied to the isolated, sealed upper airways of nine anesthetized mongrel dogs. Upper airway impedance spectra were studied during sequential 350 msec epochs. We found spectral changes which were reproducible within the respiratory cycle. Impedance spectra revealed that during mid-inspiration at the point of peak upper airway muscle activity, the low frequency real part decreased and the imaginary part was less negative and less steep. During late inspiration and early expiration the impedance values returned to their end-expiratory values. The only significant change in parameter estimates from a three-parameter model indicated an increase in compliance. Since these changes correlated not only with tidal flow through the lower trachea and lung but also with upper airway muscle activation, we reasoned that changes in impedance could have resulted from an increase in upper airway size. Therefore, we used a sealed speaker system and, while the animal was apnoeic, evaluated impedance at two different airway pressures and the resultant volumes. The changes in impedance spectra with a volume increase were similar to those seen during spontaneous breathing efforts. We conclude that the mechanical properties of the upper airway change during the respiratory cycle and that these changes correlate with the respiratory activation of upper airway muscles. We suspect that these changes in input impedance could reflect a change in the size of the airway rather than a true increase in elasticity.     

Optical Constants of Crystallized TiO2 Coatings Prepared by Sol-Gel Process

Titanium oxide coatings have been deposited by the sol-gel dip-coating method. Crystallization of titanium oxide coatings was then achieved through thermal annealing at temperatures above 400 °C. The structural properties and surface morphology of the crystallized coatings were studied by micro-Raman spectroscopy and atomic force microscopy, respectively. Characterization technique, based on least-square fitting to the measured reflectance and transmittance spectra, is used to determine the refractive indices of the crystallized TiO₂ coatings. The stability of the synthesized sol was also investigated by dynamic light scattering particle size analyzer. The influence of the thermal annealing on the optical properties was then discussed. The increase in refractive index with high temperature thermal annealing process was observed, obtaining refractive index values from 1.98 to 2.57 at He-Ne laser wavelength of 633 nm. The Raman spectroscopy and atomic force microscopy studies indicate that the index variation is due to the changes in crystalline phase, density, and morphology during thermal annealing.     

山区丘陵型血吸虫病传播控制地区防治措施变化与成本-效果评价I疫情调查及流行因素分析

目的调查与分析山区丘陵型血吸虫病流行区达到传播控制标准(传控达标)后疾病流行现状及影响因素,为同类地区制定实现传播阻断目标的策略和措施提供参考依据。方法选择2008年传控达标的四川省眉山市东坡区为研究区,收集2008-2010年血吸虫病疫情资料;于2011年4-11月开展血吸虫病流行因素现况调查,采用系统抽样结合环境抽查法调查钉螺分布情况,采用血清免疫学和粪便孵化法筛查当地常住居民血吸虫感染情况,采用塑料杯顶管孵化法普查散养耕牛血吸虫感染情况,采用问卷法调查当地居民疫水接触情况。选择2006年传控达标的德阳市旌阳区和2007年传控达标的眉山市仁寿县的2个村为传播风险快速评估调查点,采用简单随机抽样结合快速现场评估方法,于2011年对钉螺和感染性钉螺分布、野粪和含血吸虫卵野粪分布等情况进行调查。结果2008-2010年眉山市东坡区检查居民18.26万～21.33万人,人群血检阳性率为6.30%～6.81%,血吸虫感染率为0.02%～0.07%;共检查耕牛2 835～7 260头,未发现血吸虫感染病畜;发现钉螺面积190.00～232.00 hm2,活螺密度0.02～0.19只/0.1 m2,未发现感染性钉螺。2011年,东坡区共检查居民20.44万人,血检阳性率为4.98%,未发现粪检阳性者;普查散放耕牛1 735头,未发现粪检阳性牛;共查出有螺面积99.00 hm2,活螺密度为0.18只/0.1 m2,未发现感染性钉螺;共在4个村对537名居民进行问卷调查,沟、渠、塘、水田等是当地居民主要接触疫水环境,其中沟和水田环境在传控达标前和达标后的年平均接触频次中位数分别为20、30人次和15、30人/次(χ沟2=1.61,χ水田2=0.03,P均>0.05);渠和塘达标前年平均接触频次中位数分别为15人次和30人次,而在达标后则明显减少(χ渠2=10.35,χ塘2=18.69,P均<0.01)。2011年2个村的快速评估调查显示,有螺框平均出现率分别为60.15%和12.12%,活螺平均密度分别为1.19只/0.1 m2和0.20只/0.1 m2,均未发现感染性钉螺;共采集牛、羊等野粪78份,经孵化检查未发现阳性。结论山区丘陵型血吸虫病流行区传控达标后,防治成果较为巩固,但潜在流行因素依然存在,表现为人群血检阳性率较高,耕牛数量较多,潜在传染源依然存在;钉螺面积和活螺密度下降不明显。提示亟需开发、研究更适宜的防治新技术和新措施,加快推进山丘地区的血防工作进程。     

Mn2(+)-binding properties of a recombinant protein-tyrosine kinase derived from the human insulin receptor.

The divalent cation-binding properties of the human insulin receptor tyrosine kinase domain were examined kinetically and by electron paramagnetic resonance and circular dichroic spectroscopy. The protein-tyrosine kinase activity of the purified cytoplasmic domain can be activated nearly 10-fold by 3 mM Mn2+ in the presence or absence of 5 mM Mg2+. Electron paramagnetic resonance spectra of the purified, acid-denatured kinase domain and assays of EDTA-treated kinase show that the purified protein does not possess residual, tightly bound Mn2+. Electron paramagnetic resonance spectroscopy was used to directly measure the binding constant of the kinase domain for Mn2+. The results indicate that the recombinant cytoplasmic domain of the human insulin receptor does not bind Mn2+ tightly in the absence or presence of MgATP (Kd greater than 0.8 mM). Furthermore, the enzyme does not show a strong preference for MnATP binding when both MgATP and MnATP are present. The far-ultraviolet circular dichroic spectrum of this domain is characterized by a negative maximum at 207 nm. In the presence of Mn2+, but not Mg2+, changes in the mean residue-weight ellipticity at 207 nm occur that are consistent with a decrease in alpha-helical content. The addition of ATP to Mn2(+)-bound protein does not further perturb the spectrum. We conclude that Mn2+ ions, although they bind weakly, induce an activating conformational change in the secondary structure of the human insulin receptor cytoplasmic domain. Activation by Mn2+ is unlikely to be significant in intact cells, but it may mimic the action of a physiological activator.     

Intermediate spectra and photocycle kinetics of the Asp96 --> asn mutant bacteriorhodopsin determined by singular value decomposition with self-modeling

Singular value decomposition with self-modeling is applied to resolve the intermediate spectra and kinetics of the Asp96 --> Asn mutant bacteriorhodopsin. The search for the difference spectra of the intermediates is performed in eigenvector space on the stoichiometric plane. The analysis of data at pH values ranging from 4 to 8 and temperatures between 5 and 25 degrees C reveals significant, early partial recovery of the initial state after photoexcitation. The derived spectra are not biased by assumed photocycles. The intermediate spectra derived in the initial step differ from spectra determined in prior analyses, which results in intermediate concentrations with improved stoichiometric properties. Increasingly more accurate photocycles follow with increasing assumed complexity, of which parallel models are favored, consistent with recent, independent experimental evidence.     

Reproducibility of the vesicular breath sounds in normal subjects.

Nonfiltered (NF) lung sounds from the apical area of the heart along with lung volumes and ECG signals were recorded from 5 normal subjects. The signals were digitized and subjected to three methods of heart sound cancellation: 75-Hz high-pass filtering (75 HF), ECG-triggered blanking (BL) and adaptive noise cancelling (AF) [IEEE Trans. Biomed. Engng 33: 1141-1148, 1986]. The sound signals were then subjected to the fast Fourier transform algorithm to obtain power spectra. Five breaths from each subject were analyzed, and their spectra were similar and slightly skewed to the right. The average values of mean, median and mode frequencies of the whole breath of 5 subjects, respectively, were for NF: 64.62 +/- 3.74, 44.57 +/- 2.06 and 36.75 +/- 1.79 Hz; for 75 HF: 150.42 +/- 17.49, 114.02 +/- 6.43 and 86.16 +/- 3.13 Hz; for BL: 81.76 +/- 6.02, 52.36 +/- 2.79, 41.10 +/- 3.15 Hz; for AF: 96.87 +/- 11.58, 68.23 +/- 10.44 and 52.25 +/- 8.97 Hz. These values showed no differences between subjects. The F values obtained by the two-way analysis of variance of all breaths of all subjects (mean, median, mode) were: NF: 0.161, 0.341, 0.089; 75 HF: 0.455, 0.042, 0.085; BL: 0.108, 0.082, 0.057; AF: 0.130, 0.204, 0.113 (all p greater than 0.1). The data revealed a remarkable lack of variation within and between subjects, suggesting similar sites and mechanisms of production and transmission.     

Exploration of Free Energy Surface and Thermal Effects on Relative Population and Infrared Spectrum of the Be6B11− Fluxional Cluster

The starting point to understanding cluster properties is the putative global minimum and all the nearby local energy minima; however, locating them is computationally expensive and difficult. The relative populations and spectroscopic properties that are a function of temperature can be approximately computed by employing statistical thermodynamics. Here, we investigate entropy-driven isomers distribution on Be₆B₁₁⁻ clusters and the effect of temperature on their infrared spectroscopy and relative populations. We identify the vibration modes possessed by the cluster that significantly contribute to the zero-point energy. A couple of steps are considered for computing the temperature-dependent relative population: First, using a genetic algorithm coupled to density functional theory, we performed an extensive and systematic exploration of the potential/free energy surface of Be₆B₁₁⁻ clusters to locate the putative global minimum and elucidate the low-energy structures. Second, the relative populations’ temperature effects are determined by considering the thermodynamic properties and Boltzmann factors. The temperature-dependent relative populations show that the entropies and temperature are essential for determining the global minimum. We compute the temperature-dependent total infrared spectra employing the Boltzmann factor weighted sums of each isomer’s infrared spectrum and find that at finite temperature, the total infrared spectrum is composed of an admixture of infrared spectra that corresponds to the spectra of the lowest-energy structure and its isomers located at higher energies. The methodology and results describe the thermal effects in the relative population and the infrared spectra.     

Improved assessment of intravascular Doppler coronary flow velocity profile

Easy and safe in- vivo flow velocity studies in small coronary arteries have become feasible using a 0.014 or 0.018 guidewire with an integrated Doppler probe in its tip (FloWire, Cardiometrics). Assessment of the flow velocity profile by the ratio of diastolic to systolic flow velocity (DSVR) is used as a diagnostic parameter. However, DSVR is a coarse quantifier of the flow velocity profile, and is subject to large physiologic variance and depends crucially on the quality of the Doppler signal. The aim of our study was to test parameters derived from statistical time series analysis for monitoring the quality of the instantaneous peak velocity (IPV) signal. Improvement of quantification of changes in quality and shape of flow velocity profiles by these parameters as compared to DSVR was a second goal.We investigated analog-digital converted IPV- signals and video registrations of corresponding greyscale spectra of intracoronary Doppler flow velocity signals. The signals were analyzed by using the autocorrelation function (ACF) in the time domain and a fast Fourier transform (FFT) in the frequency domain (standard time series statistics). The first minimum of autocorrelation function turned out to be very sensitive to signal quality, and Fisher's g of the periodogram was the parameter of choice for shape analysis. In 11 patients with coronary artery disease, pre and post PTCA, the sensitivity of DSVR and signal to noise ratio to changes in shape and quality of the flow velocity signals was compared to that of the new parameters. Nineteen Doppler flow velocity samples of good quality from measurements in nonstenotic vessels and 7 flow velocity tracings with visible artefacts were used to assess the value of these parameters in monitoring signal quality.By comparison with corresponding parameters in use (SNR and DSVR) a significantly improved performance of the new statistical parameters was observed with respect to sensitivity to changes in signal quality and flow profile. In view of these results and because of the short calculation time of these variables they should be used for on-line quality control and analysis of flow velocity profiles.