Search

Abstract: Pharmacological measurement of baroreflex sensitivity (BRS) is widely accepted and used in clinical practice. Following the introduction of pharmacologically induced BRS (p-BRS), alternative assessment methods eliminating the use of drugs were in the center of interest of the cardiovascular research community. In this study we investigated whether p-BRS using phenylephrine injection can be predicted from non-pharmacological time and frequency domain indices computed from electrocardiogram (ECG) and blood pressure (BP) data acquired during deep breathing. In this scheme, ECG and BP data were recorded from 16 subjects in a two-phase experiment. In the first phase the subjects performed irregular deep breaths and in the second phase the subjects received phenylephrine injection. From the first phase of the experiment, a large pool of predictors describing the local characteristic of beat-to-beat interval tachogram (RR) and systolic blood pressure (SBP) were extracted in time and frequency domains. A subset of these indices was selected using twelve subjects with an exhaustive search fused with a leave one subject out cross validation procedure. The selected indices were used to predict the p-BRS on the remaining four test subjects. A multivariate regression was used in all prediction steps. The algorithm achieved best prediction accuracy with only two features extracted from the deep breathing data, one from the frequency and the other from the time domain. The normalized L2-norm error was computed as 22.9% and the correlation coefficient was 0.97 (p=0.03). These results suggest that the p-BRS can be estimated from non-pharmacological indices computed from ECG and invasive BP data related to deep breathing. [Copyright &y& Elsevier]

This paper presents a sequence of signal processing and hierarchical clustering techniques utilized to process signals with low signal-to-noise ratio (SNR) measured by multiple AE sensors. Noise and other extraneous events present major challenges for the detection and monitoring of AE signals generated by the inception of microcracks and their growth. Characteristics of AE waveforms released during controlled mode-I fracture are explored, and these characteristics are used for clustering AE and locating the fracture. With hierarchical clustering and signal "denoising" techniques, it is possible to locate the position of the crack plane with high accuracy using AE signals of poor quality, wherein the spatial distribution of clusters is indicative of crack propagation. [ABSTRACT FROM AUTHOR]

A new adaptive time-frequency (t-f) analysis and classification procedure is applied to impact acoustic signals for detecting hazelnuts with cracked shells and three types of damaged wheat kernels. Kernels were dropped onto a steel plate, and the resulting impact acoustic signals were recorded with a PC-based data acquisition system. These signals were segmented with a flexible local discriminant bases (F-LDB) procedure in the time-frequency plane to extract discriminative patterns between damaged and undamaged food kernels. The F-LDB procedure requires no prior knowledge of the relevant time or frequency indices of the impact acoustics signals for classification. The method automatically finds all crucial time-frequency indices from the training data by combining local cosine packet analysis and a frequency axis clustering approach, which supports individual time and frequency band adaptation. Diseriminant features are extracted from the adaptively segmented acoustic signal, sorted according to a Fisher class separability criterion, post-processed by principal component analysis, and fed to a linear discriminant classifier. Experimental results establish the superior performance of the proposed approach when compared to prior techniques reported in the literature or used in the field. The new approach separated damaged wheat kernels (IDK, pupal, and scab) from undamaged wheat kernels with 96%, 82%, and 94% accuracy, respectively. It also separated cracked-shell hazelnuts from those with undamaged shells with 97.1% accuracy. The adaptation capability of the algorithm to the time-frequency patterns of signals makes it a universal method for food kernel inspection that can resist the impact acoustic variability between different kernel and damage types. [ABSTRACT FROM AUTHOR]

Treatability of textile dye-bath effluents by advanced oxidation with Fenton and Fenton-like reagents (FeII/ H2O2 and FeIII/ H2O2), in the presence and absence ofUV light was investigated, using a reactive azo-dye (Procion Red HE7B), and typical dye bath constituents. Under the experimental conditions employed, it was found that with 20 min UV irradiation, complete color removal and 79% total organic carbon degradation is possible, when the system is operated at pH=3, and with a H2O2/Fe(II) molar ratio of 20:1. The increased dissolved solids content of the treated solution implies the necessity of an appropriate membrane system to make the effluent reusable in the dye/wash processes. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved. [ABSTRACT FROM AUTHOR]

This study presents the results of morphometric analysis of a total of 473 skulls ascribed to adult animals were sufficiently complete to allow the measurement of their foramen magnum; and for 472 of them the foramen magnum index could be calculated. The dorsal notch was only seen in the group of mesocephalic dogs where about 17% of all skulls exhibited this feature. The average length of the dorsal notch was found to be 2.59 mm. Not a single skull in the dolichocephalic dog group showed any sign of a dorsal notch. The results of this study show that the dorsal notch in the foramen magnum widely seen dogs of the Middle Ages, and point to a morphological variation. [ABSTRACT FROM AUTHOR]

Study design:Prospective cohort study.Objectives:To compare the health-related quality of life (HRQoL) in people with spinal cord injury (SCI) who use the Internet versus those who don't and with a control group of able-bodied individuals. To investigate the frequency of Internet usage before and after injury. To evaluate the differences in terms of demographic features of both groups, analyze the variation in the Internet usage pattern of people with SCI before and after the injury.Setting:Istanbul, Turkey.Methods:A total of 60 people with SCI (38 Internet users, 22 nonusers) were included in the study. The control group consisted of 33 healthy persons of similar age and sex. The HRQoL was evaluated with the SF-36 Health Survey.Results:The scores of all the subscales of the SF-36, except vitality, were significantly lower in people with SCI than those of the controls'. The bodily pain subscale and physical component scores were found to be significantly higher in people with SCI using the Internet than the nonuser group with SCI (P<0.05). The Internet usage frequency increased significantly in people with SCI after injury (P<0.05). A significant correlation was found between time since injury and Internet use (r=0.365, P=0.007).Conclusion:Although HRQoL scores were lower in people with an SCI, the physical status component score was better in the Internet user SCI group. As there is a significant increase in the time spent online after injury, the Internet could be an effective modality to contact and educate people with an SCI. [ABSTRACT FROM AUTHOR]

Smoothness is an important factor in consumer perception of tissue quality, with physical modification and chemical additions to the paper able to enhance tissue handle. Therefore objective measurement of the papers mechanical properties in developing new products and maintaining existing quality is vital. In this study the surface chemical composition of the softener treated paper is investigated using ToF-SIMS, and related to the surface frictional properties of the paper. [ABSTRACT FROM AUTHOR]