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Root Mean Square (root + mean_square)
Terms modified by Root Mean Square Selected AbstractsPreliminary rapport on head posture and muscle activity in subjects with class I and IIJOURNAL OF ORAL REHABILITATION, Issue 11 2005I. C. GADOTTI summary, Forward head posture may cause alterations in the stomatognathic system, including changes in the muscle activity of the masticatory muscles and dental occlusion alterations. Considering the need for further understanding of the relationship between the stomatognathic system and the cervical region, the purpose of this study was to analyse the head posture and the electromyographic (EMG) activity of the anterior portion of temporal and masseter muscles bilaterally among bruxist's subjects with different dental occlusion classifications using the Angle method. The study consisted of 20 female volunteers, between the ages of 17 and 27 years. They were separated into two groups (class I and class II occlusions) according to a dentist-performed evaluation. An assessment of forward head posture was conducted using a photographic technique (angular calculus) combined with a clinical analysis. In the EMG analyses, active differential surface electrodes (Ag) were utilized and were placed bilaterally on the belly of masseter and temporal muscles, perpendicular to the muscles fibres. The EMG signal recorded during bilateral isotonic mastication, was presented using the Root Mean Square and was processed by Matlab software. The results indicated that the EMG responses of temporal and masseter muscles tend to be modified by occlusion alteration class II. Subjects with class II occlusion tended to present more occurrence of forward head posture with alterations in the muscle activity pattern between masseter and temporal muscles. [source] Optical aberration measurements in dog and cat eyes: interest & limitACTA OPHTHALMOLOGICA, Issue 2008SG ROSOLEN Purpose To measure the ocular optical aberrations in dog and cat using a wavefront aberrometer based on Hartmann-Shack technology. Methods Two dogs and one cat were sedated (Medetomidine, 0.1 mg/kg) and their right eye (RE) pupils were artificially dilated (tropicamide). Wavefront aberrations were measured using an irx3 aberrometer (Imagine Eyes, Orsay, France). Prior to each measurement, the eye was aligned with the instrument optical axis by centering both the eye pupil and Purkinje images. The Hartmann-Shack spot images were produced by an array of 1024 microlenses that defined a 7.2x7.2 mm square area in the pupil plane. In preliminary tests, spot image histograms were optimized by adjusting the sensor acquisition time. Wavefront aberrations were then repeatedly measured 10 times in each animal's RE. Spherical defocus, astigmatism and Zernike coefficients up to the 8th order were finally analyzed. Results The optimal acquisition time was 10 ms for all animals, instead of 33 ms when measuring human eyes. Refractive errors could be analyzed in a 6 mm pupil diameter in all cases. The dilated pupil often exceed the sensor area. The average refractive errors in dog #1, dog #2 and the cat were +2.9D(-2.0D)111°;-0.8D(-0.8D)126° and +3.3D(-2.1D)98°, respectively while their Root Mean Square (RMS) higher-order aberrations amounted to 1.9, 1.1, and 2.1 µm RMS respectively. Standard deviation in sphere and cylinder was 1.0D in the cat and less than 0.5D in both dogs. Standard deviation in the higher-order RMS was 0.8 µm in the cat and less than 0.5 µm in both dogs. The observation of individual data revealed that a significant part of this variability was due to blink-related changes in aberrations. Conclusion Ocular optical aberrations can be easily measured in dog and cat using a Hartmann-Shack aberrometer with reduced image acquisition time. The tested animals had relatively large higher-order wavefront aberrations when compared to date measured in healthy human eyes. Measurement reproducibility was notably affected by tear layer effects. This variability could probably be reduced using a larger sensor area, specific head contention device and artificial tears. This new diagnostic technique is easily feasible without any use of anaesthesia and provides less variability and more detailed information than skiascopy. Wavefront aberrometry could be useful in both research and clinical applications. [source] Influence of playing wind instruments on activity of masticatory musclesJOURNAL OF ORAL REHABILITATION, Issue 9 2007A. GOTOUDA Summary, The aim of this study was to elucidate the influence of change in sound tone of playing wind instruments on activity of jaw-closing muscles and the effect of sustained playing for a long time on fatigue of jaw-closing muscles. Electromyograms (EMG) of 19 brass instrument players and 14 woodwind instrument players were measured while playing instruments in tuning tone and high tone and under other conditions. Nine brass instrument players and nine woodwind instrument players played instruments for 90 min. Before and after the exercise, power spectral analyses of EMG from masseter muscles at 50% of maximum voluntary clenching level were performed and mean power frequency (MPF) were calculated. Root mean square (RMS) of EMG in masseter and temporal muscles while playing were slightly larger than those at rest but extremely small in comparison with those during maximum clenching. Root mean square in orbicularis oris and digastric muscles were relatively large when playing instruments. In the brass instrument group, RMS in high tone was significantly higher than that in tuning tone in all muscles examined. In the woodwind instrument group, RMS in high tone was not significantly higher than that in tuning tone in those muscles. Mean power frequency was not decreased after sustained playing in both instrument groups. These findings indicate that contractive load to jaw-closing muscles when playing a wind instrument in both medium and high tone is very small and playing an instrument for a long time does not obviously induce fatigue of jaw-closing muscles. [source] Decentralized Parametric Damage Detection Based on Neural NetworksCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 3 2002Zhishen Wu In this paper, based on the concept of decentralized information structures and artificial neural networks, a decentralized parametric identification method for damage detection of structures with multi-degrees-of-freedom (MDOF) is conducted. First, a decentralized approach is presented for damage detection of substructures of an MDOF structure system by using neural networks. The displacement and velocity measurements from a substructure of a healthy structure system and the restoring force corresponding to this substructure are used to train the decentralized detection neural networks for the purpose of identifying the corresponding substructure. By using the trained decentralized detection neural networks, the difference of the interstory restoring force between the damaged substructures and the undamaged substructures can be calculated. An evaluation index, that is, relative root mean square (RRMS) error, is presented to evaluate the condition of each substructure for the purpose of health monitoring. Although neural networks have been widely used for nonparametric identification, in this paper, the decentralized parametric evaluation neural networks for substructures are trained for parametric identification. Based on the trained decentralized parametric evaluation neural networks and the RRMS error of substructures, the structural parameter of stiffness of each subsystem can be forecast with high accuracy. The effectiveness of the decentralized parametric identification is evaluated through numerical simulations. It is shown that the decentralized parametric evaluation method has the potential of being a practical tool for a damage detection methodology applied to structure-unknown smart civil structures. [source] The influence of pool length on local turbulence production and energy slope: a flume experimentEARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2004Douglas M. Thompson Abstract The in,uence of pool length on the strength of turbulence generated by vortex shedding was investigated in a 6 m long recirculating ,ume. The experiment utilized a 38% constriction of ,ow and an average channel-bed slope of 0·007. The base geometry for the intermediate-length pool experiment originated from a highly simpli,ed, 0·10 scale model of a forced pool from North Saint Vrain Creek, Colorado. Discharge in the ,ume was 31·6 l/s, which corresponds to a discharge in the prototype channel of 10 m3/s. Three shorter and four longer pool lengths also were created with a ,xed bed to determine changes in turbulence intensities and energy slope with pool elongation. Three-dimensional velocities were measured with an acoustic Doppler velocimeter at 31,40 different 0·6-depth and near-bed locations downstream of the rectangular constriction. The average velocity and root mean square (RMS) of the absolute magnitude of velocity at both depths are signi,cantly related to the distance from the constriction in most pool locations downstream of the constriction. In many locations, pool elongation results in a non-linear change in turbulence intensities and average velocity. Based on the overall ,ow pattern, the strongest turbulence occurs in the center of the pool along the shear zone between the jet and recirculating eddy. The lateral location of this shear zone is sensitive to changes in pool length. Energy slope also was sensitive to pool length due to a combination of greater length of the pool and greater head loss with shorter pools. The results indicate some form of hydraulic optimization is possible with pools adjusting their length to adjust the location and strength of turbulent intensities in the center of pools, and lower their rate of energy dissipation. Copyright © 2004 John Wiley & Sons, Ltd. [source] Prior pallidotomy reduces and modifies neuronal activity in the subthalamic nucleus of Parkinson's disease patientsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2008A. Zaidel Abstract Parkinson's disease (PD) patients with prior radio-frequency lesions in the internal segment of the globus pallidus (GPi, pallidotomy), whose symptoms have deteriorated, may be candidates for further invasive treatment such as subthalamic deep brain stimulation (STN DBS). Six patients with prior pallidotomy (five unilaterally; one bilaterally) underwent bilateral STN DBS. The microelectrode recordings (MERs, used intraoperatively for STN verification), ipsilateral and contralateral to pallidotomy, and MERs from 11 matched PD patients who underwent bilateral STN DBS without prior pallidotomy were compared. For each trajectory, average, variance and mean successive difference (MSD, a measure of irregularity) of the root mean square (RMS) of the STN MER were calculated. The RMS in trajectories ipsilateral to pallidotomy showed significant reduction of the mean average and MSD of STN activity when compared with trajectories from patients without prior pallidotomy. The RMS parameters contralateral to pallidotomy tend to lie between those ipsilateral to pallidotomy and those without prior pallidotomy. The average STN power spectral density of oscillatory activity was notably lower ipsilateral to pallidotomy than contralateral, or without prior pallidotomy. The finding that pallidotomy reduces STN activity and changes firing characteristics, in conjunction with the effectiveness of STN DBS despite prior pallidotomy, calls for reappraisal and modification of the current model of the basal ganglia (BG) cortical network. It highlights the critical role of direct projections from the BG to brain-stem structures and suggests a possible GPi,STN reciprocal positive-feedback mechanism. [source] EMG and Oxygen Uptake Responses During Slow and Fast Ramp Exercise in HumansEXPERIMENTAL PHYSIOLOGY, Issue 1 2002Barry W. Scheuermann This study examined the relationship between muscle recruitment patterns using surface electromyography (EMG) and the excess O2 uptake (ExV,O2) that accompanies slow (SR, 8 W min,1) but not fast (FR, 64 W min,1) ramp increases in work rate (WR) during exercise on a cycle ergometer. Nine subjects (2 females) participated in this study (25 ± 2 years, ± S.E.M.). EMG was obtained from the vastus lateralis and medialis and analysed in the time (root mean square, RMS) and frequency (median power frequency, MDPF) domain. Results for each muscle were averaged to provide an overall response and expressed relative to a maximal voluntary contraction (%MVC). ,V,O2/,WR was calculated for exercise below (S1) and above (S2) the lactate threshold (LT) using linear regression. The increase in RMS relative to the increase in WR for exercise below the LT (,RMS/,WR-S1) was determined using linear regression. Due to non-linearities in RMS above the LT, ,RMS/,WR-S2 is reported as the difference in RMS (,RMS) and the difference in WR (,WR) at end-exercise and the LT. SR was associated with a higher (P < 0.05) ,V,O2/,WR (S1, 9.3 ± 0.3 ml min,1 W,1; S2, 12.5 ± 0.6 ml min,1 W,1) than FR (S1, 8.5 ± 0.4 ml min,1 W,1; S2, 7.9 ± 0.4 ml min,1 W,1) but a similar ,RMS/,WR-S1 (SR, 0.11 ± 0.01% W,1; FR, 0.10 ± 0.01% W,1). ExV,O2 was greater (P < 0.05) in SR (3.6 ± 0.7 l) than FR (-0.7 ± 0.4 l) but was not associated with a difference in either ,RMS/,WR-S2 (SR, 0.14 ± 0.01% W,1; FR, 15 ± 0.02% W,1) or MDPF (SR, 2.6 ± 5.9%; FR, -15.4 ± 4.5%). The close matching between power output and RMS during SR and FR suggests that the ExV,O2 of heavy exercise is not associated with the recruitment of additional motor units since ExV,O2 was observed during SR only. Compared to the progressive decrease in MDPF observed during FR, the MDPF remained relatively constant during SR suggesting that either (i) there was no appreciable recruitment of the less efficient type II muscle fibres, at least in addition to those recruited initially at the onset of exercise, or (ii) the decrease in MDPF associated with fatigue was offset by the addition of a higher frequency of type II fibres recruited to replace the fatigued motor units. [source] Co-seismic slip from the 1995 July 30 Mw= 8.1 Antofagasta, Chile, earthquake as constrained by InSAR and GPS observationsGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2002M. E. Pritchard Summary We analyse radar interferometric and GPS observations of the displacement field from the 1995 July 30 Mw= 8.1 Antofagasta, Chile, earthquake and invert for the distribution of slip along the co-seismic fault plane. Using a fixed fault geometry, we compare the use of singular-value decomposition and constrained linear inversion to invert for the slip distribution and find that the latter approach is better resolved and more physically reasonable. Separate inversions using only GPS data, only InSAR data from descending orbits, and InSAR data from both ascending and descending orbits without the GPS data illustrate the complimentary nature of GPS and the presently available InSAR data. The GPS data resolve slip near GPS benchmarks well, while the InSAR provides greater spatial sampling. The combination of ascending and descending InSAR data contributes greatly to the ability of InSAR to resolve the slip model, thereby emphasizing the need to acquire this data for future earthquakes. The rake, distribution of slip and seismic moment of our preferred model are generally consistent with previous seismic and geodetic inversions, although significant differences do exist. GPS data projected in the radar line-of-sight (LOS) and corresponding InSAR pixels have a root mean square (rms) difference of about 3 cm. Comparison of our predictions of vertical displacement and observed uplift from corraline algae have an rms of 10 cm. Our inversion and previous results reveal that the location of slip might be influenced by the 1987 Mw= 7.5 event. Our analysis further reveals that the 1995 slip distribution was affected by a 1988 Mw= 7.2 event, and might have influenced a 1998 Mw= 7.0 earthquake that occurred downdip of the 1995 rupture. Our slip inversion reveals a potential change in mechanism in the southern portion of the rupture, consistent with seismic results. Predictions of the satellite LOS displacement from a seismic inversion and a joint seismic/GPS inversion do not compare favourably with the InSAR observations. [source] The Impact of Interfacial Mixing on Förster Transfer at Conjugated Polymer HeterojunctionsADVANCED FUNCTIONAL MATERIALS, Issue 1 2009Anthony M. Higgins Abstract Neutron reflectivity and photoluminescence measurements are reported on bilayers of polyfluorene-based conjugated polymers. By using a novel thermal processing procedure it is possible to control the width of the interface between poly(9,9-dioctylfluorene) (F8) and poly(9,9-dioctylfluorene- alt -benzothiadiazole) (F8BT), and measure the impact of interfacial roughness on the resonant energy transfer of excitons at the interface (Förster transfer). It is found that increasing the root mean square (rms) roughness of the F8/F8BT interface over the range of ,1,nm to ,5,nm leads to a greatly enhanced Förster transfer from F8 to F8BT molecules. By comparing photoluminescence measurements with simple calculations it is concluded that the level of enhancement of the F8BT peak at rough interfaces can only be adequately explained if mixing of F8 and F8BT at a molecular level dominates over the interfacial roughness due to thermally excited capillary waves. [source] Active microwave remote sensing for soil moisture measurement: a field evaluation using ERS-2HYDROLOGICAL PROCESSES, Issue 11 2004Jeffrey P. Walker Abstract Active microwave remote sensing observations of backscattering, such as C-band vertically polarized synthetic aperture radar (SAR) observations from the second European remote sensing (ERS-2) satellite, have the potential to measure moisture content in a near-surface layer of soil. However, SAR backscattering observations are highly dependent on topography, soil texture, surface roughness and soil moisture, meaning that soil moisture inversion from single frequency and polarization SAR observations is difficult. In this paper, the potential for measuring near-surface soil moisture with the ERS-2 satellite is explored by comparing model estimates of backscattering with ERS-2 SAR observations. This comparison was made for two ERS-2 overpasses coincident with near-surface soil moisture measurements in a 6 ha catchment using 15-cm time domain reflectometry probes on a 20 m grid. In addition, 1-cm soil moisture data were obtained from a calibrated soil moisture model. Using state-of-the-art theoretical, semi-empirical and empirical backscattering models, it was found that using measured soil moisture and roughness data there were root mean square (RMS) errors from 3·5 to 8·5 dB and r2 values from 0·00 to 0·25, depending on the backscattering model and degree of filtering. Using model soil moisture in place of measured soil moisture reduced RMS errors slightly (0·5 to 2 dB) but did not improve r2 values. Likewise, using the first day of ERS-2 backscattering and soil moisture data to solve for RMS surface roughness reduced RMS errors in backscattering for the second day to between 0·9 and 2·8 dB, but did not improve r2 values. Moreover, RMS differences were as large as 3·7 dB and r2 values as low as 0·53 between the various backscattering models, even when using the same data as input. These results suggest that more research is required to improve the agreement between backscattering models, and that ERS-2 SAR data may be useful for estimating fields-scale average soil moisture but not variations at the hillslope scale. Copyright © 2004 John Wiley & Sons, Ltd. [source] Laminar separation bubble on an Eppler 61 airfoilINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 6 2010Samir B. Savaliya Abstract Laminar separation bubble that occurs on the suction side of the Eppler 61 airfoil at Re=46000 is studied. The incompressible flow equations are solved using a stabilized finite element method. No turbulence model is used. The variation of the bubble length and its location, with the angle of attack (,), is studied in detail. An abrupt increase in the lift coefficient is observed at ,,4.5°. It is found to be related to a sudden decrease in the separation bubble length at the trailing edge of the airfoil. Significant differences are observed in the results from the 2D and 3D computations. Stall is observed in 3D simulations, but is found to be absent in 2D. The laminar bubble, which fails to reattach in 3D for ,>14°, continues to reattach for , as large as 20° in the 2D computations. Reynolds stress calculations in both 2D and 3D indicate the extent to which the outer flow is affected by the presence of bubble. It is found that the Reynolds stress components and are of comparable order of magnitude indicating that spanwise fluctuations are significant. The effect of the time window used to compute the time-averaged aerodynamic coefficients is studied. The time-averaged and root mean square (rms) value of the aerodynamic coefficients are calculated for both 2D and 3D computations and compared with the previously published experimental results. The 3D computations show good agreement with the earlier data. The variation of the rms value of the aerodynamic coefficients with angle of attack shows certain peaks. The cause of their appearance is investigated. The effect of Reynolds number is studied. The increase in Re at ,=10° is found to reduce the bubble length and cause it to move closer to the leading edge. Copyright © 2009 John Wiley & Sons, Ltd. [source] Dual diversity combining and decision feedback equalizer in indoor millimetre-wave channelINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 8 2002Chien-Ching Chiu Abstract Wideband communication characteristics of wireless indoor millimetre-wave channel for arched and rectangular buildings are investigated. The impulse responses of arched and rectangular buildings for any transmitter,receiver location are computed by shooting and bouncing ray/image (SBR/Image) techniques. By using the impulse responses of these multipath channels, the impact of shapes of building is presented and the bit error rate performance of binary phase shift keying (BPSK) system with phase and timing recovery circuits are also calculated. Moreover, dual space antenna diversity technique and decision feedback equalizer (DFE) with four forward and three feedback taps are used to combat the multipath fading. Numerical results show that the mean root mean square (rms) delay spread for the arched building is smaller than that for the rectangular building. In addition, it is also found that the transmission rate can be up to 20 Mbps for indoor millimetre-wave channel of these two buildings by using dual space diversity and DFE. Copyright © 2002 John Wiley & Sons, Ltd. [source] Direct detection of the protein quaternary structure and denatured entity by small-angle scattering: guanidine hydrochloride denaturation of chaperonin protein GroELJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2002Yasutaka Seki A change in the higher-order structure of an oligomeric protein is directly detectable by small-angle scattering. A small-angle X-ray scattering (SAXS) study of the denaturation process of the chaperonin protein GroEL by guanidine hydrochloride (GdnHCl) showed that the disappearance of the quaternary structure can be monitored by using a Kratky plot of the scattered intensities, demonstrating the advantage of the SAXS method over other indirect methods, such as light scattering, circular dichroism (CD), fluorescence and sedimentation. The collapse of the quaternary structure was detected at a GdnHCl concentration of 0.8,M for a solution containing ADP (adenosine diphosphate)/Mg2+(2,mM)/K+. From pairwise plots of the change in forward scattering intensity J(0)/C (weight-average molecular weight) and the z -average (root mean square) radius of gyration against the GdnHCl concentration, the stability and nature of the denatured protein can be determined. The SAXS results suggest that the GroEL tetradecamer directly dissociates to the unfolded coil without going through a globular monomer state. The denatured ensemble is not a single unfolded monomer coil particle, but some mixture of entangled aggregates and a monomer of the coil molecules. Small-angle scattering is a powerful method for the detection and study of changes in quaternary and higher-order structures of oligomeric proteins. [source] STANDARD SCALES FOR CRISPNESS, CRACKLINESS AND CRUNCHINESS IN DRY AND WET FOODS: RELATIONSHIP WITH ACOUSTICAL DETERMINATIONSJOURNAL OF TEXTURE STUDIES, Issue 4 2008MAITE A. CHAUVIN ABSTRACT A trained panel developed rating scales for crispness, crunchiness and crackliness for dry and wet foods based on the auditory perception of selected foods. The newly developed scales were then evaluated by 40 untrained panelists and the sound perception of standard foods was assessed through the analysis of the root mean square (RMS) of the 5-s audio waveforms and multidimensional scaling (MDS). The RMS was highly correlated to auditory sensory perception of crispness (r = 0.83 and 0.96), crunchiness (r = 0.99 and 0.99) and crackliness (r = 0.88 and 0.96) for dry and wet foods, respectively. MDS technique applied for the 40 untrained panelists was instructive in assessing auditory textural differences of naďve panelists and a useful statistical instrument to graphically validate selected scales. Auditory perception of the selected foods were rated similarly using standard auditory texture scales for crispness, crunchiness and crackliness developed by the trained panel (oral evaluation) and MDS results from the untrained panel (recordings). PRACTICAL APPLICATIONS Crispness, crunchiness and crackliness are not only important and useful descriptors of food texture, but are also desirable textural qualities in many foods. The lack of consistency in the procedures used for the evaluation of crunchy, crispy and crackly in sensory studies often results in confusion when training expert panels. Research will benefit textural studies through an improvement of consistent textural definitions and development of standard scales and evaluation techniques. The crispness, crunchiness and crackliness scales developed and applied in the current study represent a new potential standard frame of reference that may be used for training panelists in texture parameters related to food auditory perception. The scales may be considered illustrations demonstrating full and practical ranges for each texture attribute with regard to analyzing auditory parameters of foods and effective objective tools for assessing panelists in descriptive analysis. [source] DFT-GIAO 1H and 13C NMR prediction of chemical shifts for the configurational assignment of 6,-hydroxyhyoscyamine diastereoisomersMAGNETIC RESONANCE IN CHEMISTRY, Issue 7 2009Marcelo A. Muńoz Abstract 1H and 13C NMR chemical shift calculations using the density functional theory,gauge including/invariant atomic orbitals (DFT,GIAO) approximation at the B3LYP/6-311G++(d,p) level of theory have been used to assign both natural diastereoisomers of 6,-hydroxyhyoscyamine. The theoretical chemical shifts of the 1H and 13C atoms in both isomers were calculated using a previously determined conformational distribution, and the theoretical and experimental values were cross-compared. For protons, the obtained average absolute differences and root mean square (rms) errors for each comparison showed that the experimental chemical shifts of dextrorotatory and levorotatory 6,-hydroxyhyoscyamines correlated well with the theoretical values calculated for the (3R,6R,2,S) and (3S,6S,2,S) configurations, respectively, whereas for 13C atoms the calculations were unable to differentiate between isomers. The nature of the relatively large chemical shift differences observed in nuclei that share similar chemical environments between isomers was asserted from the same calculations. It is shown that the anisotropic effect of the phenyl group in the tropic ester moiety, positioned under the tropane ring, has a larger shielding effect over one ring side than over the other one. Copyright © 2009 John Wiley & Sons, Ltd. [source] Interaction of Artificial and Physiological Activation of the Gastrocnemius During GaitNEUROMODULATION, Issue 2 2008Colleen C. Monaghan BSc ABSTRACT Objectives., The purpose of this research was to understand the effects of surface functional electrical stimulation (FES) of the tibial nerve on the activation of the gastrocnemius medialis of the stimulated side. Methods., FES was carried out on six healthy subjects, initiated at three different times during gait: early, mid, and late stance. Each stimulation burst consisted of 15 pulses, applied for 300 msec, at 50 Hz stimulation frequency. Mixed model statistical analysis was carried out on the median onset and offset times of the gastrocnemius medialis and the root mean square of the interpulse interval responses. Results., Results indicate that the electromyography response to FES is dependent on the time of application. The most prominent effects found in the intervals between the stimulation pulses (interpulse intervals) were found when stimulation was applied early in the stance phase. This study revealed that the only statistically significant effect on burst timing was a delay in offset timing due to mid-timed stimulation. Conclusions., We conclude that additional activation may have been compensated, at least in part, by blocking of the physiological activation during the stimulation burst. [source] A pilot study on the differences in wavefront aberrations between two ethnic groups of young generally myopic subjectsOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 6 2008Alejandro Cervińo Abstract A comparative population-based cross-sectional study design was used to examine the prevalence of wavefront patterns in two different ethnic groups, and the relationship of these patterns with ocular biometrics and gender. The Shin,Nippon SRW5000 open field autorefractor, the Wavefront Analysis Supported Customized Ablation (WASCA) wavefront analyser and the IOLMaster were used to determine wavefront aberrations, mean spherical equivalent (SE) refractive error and axial length (AL). Seventy-four eyes from 74 young healthy subjects (44 British Asians, 30 Caucasians; 36 men, 38 women; mean age 22.51 ± 3.89 years) with mean SE averaging ,1.90 ± 2.76 D (range ,10.88 to +2.19 D) were examined. Relationships between ethnicity, gender, AL and SE, against the wavefront high-order root mean square, and aberration components up to the fifth order, were assessed by using multiple regression and correlation analysis. AL on its own accounted for 4.7% of the variance in trefoil component (F1,72 = 4.602; p = 0.035), 13.7% of coma component (F1,72 = 12.536; p = 0.001), 6.1% of trefoil component (F1,72 = 5.705; p = 0.020) and 9.8% of coefficient (F1,72 = 8.908; p = 0.004). A significant model emerged (F2,71 = 6.164; p = 0.003) for ethnicity and axial length, accounting for 12.4% of variance in primary spherical aberration with ethnicity accounting for 8.4% of that variance. For Caucasian subjects, a significant correlation was found between axial length and (Pearson's correlation coefficient ,0.500; p = 0.005) and (Pearson's correlation coefficient ,0.423; p = 0.020). For British Asian subjects, AL was only correlated with coefficient (Pearson's correlation coefficient ,0.358; p = 0.017). Ethnicity is a factor to be considered in the variability of wavefront aberration, particularly spherical aberration. Relationship between AL and wavefront aberrations seems to vary between ethnicities. If higher order aberrations play a role in the emmetropization process, this may be different for different populations. [source] Refractive group differences in accommodation microfluctuations with changing accommodation stimulusOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2006Mhairi Day Abstract Purpose:, Microfluctuations of accommodation are known to increase in magnitude with increasing accommodation stimulus. Reduced sensitivity to blur in myopic subjects could also lead to increases in the magnitude of the microfluctuations. The aim of this study is to examine the effect of variations in accommodation stimulus upon the microfluctuations in different refractive groups. Methods:, Thirty-six subjects were divided into three groups depending upon their refractive error and age of onset of their myopia; 12 emmetropes (EMMs), 12 early onset myopes (EOMs) and 12 late-onset myopes (LOMs). Steady-state accommodation responses were recorded continuously for 2 min using the Shin-Nippon SRW-5000 autorefractor at a sampling rate of 52 Hz while viewing targets at accommodation stimuli levels of 0, 1, 2, 3 and 4 D in a Badal (+5 D) optical system. Results:, The EMMs and EOMs showed systematic increases in the root mean square (r.m.s.) value of the microfluctuations with increasing accommodation stimulus. In contrast, no systematic variation with accommodation stimulus was found for the LOMs. Power spectrum analysis demonstrated that increases in the size of the microfluctuations were mediated by increases in the power of the low frequency components of the accommodation response. Conclusions:, The magnitude of the microfluctuations in the EMMs and EOMs may be influenced primarily by accommodation response-induced zonular relaxation effects or to changes in the physical properties of the accommodation plant with increasing accommodation response. The LOMs may have an increased baseline neural blur threshold, which appears to modulate the magnitude of the accommodative microfluctuations for low accommodation levels. At higher accommodation demands, the changes in the physical properties of the accommodation plant or the zonular relaxation effects appear to exceed the blur threshold, and the known association between microfluctuations and accommodation stimulus level is restored. [source] Left Atrial Ablation at the Anatomic Areas of Ganglionated Plexi for Paroxysmal Atrial FibrillationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 10 2010EVGENY POKUSHALOV M.D., Ph.D. Background:,Modification of left atrial ganglionated plexi (GP) is a promising technique for the treatment of paroxysmal atrial fibrillation (AF) but its therapeutic efficacy is not established. This study aimed at evaluating the effectiveness of anatomic GP modification by means of an implantable arrhythmia monitoring device. Methods:,In 56 patients with paroxysmal AF, radiofrequency ablation at anatomic sites, where the main clusters of GP have been identified in the left atrium, was performed. In all patients, an electrocardiogram monitor (Reveal XT, Medtronic Inc., Minneapolis, MN, USA) was implanted before (n = 7) or immediately after (n = 49) AF ablation. Results:,Average duration of the procedure was 142 ± 18 min and average fluoroscopy time 20 ± 7 min. In total, 53,81 applications of RF energy were delivered (mean of 18.2 ± 3.8 at each of the four areas of GP ablation). Heart rate variability was assessed in 31 patients. Standard deviation of RR intervals over the entire analyzed period, the root mean square of differences between successive RR intervals, and high frequencies decreased, while HRmin, HRmean, and LF to HF ratio increased immediately postablation; these values returned to baseline 6 months after the procedure. At end of 12-month follow-up, 40 (71%) patients were free of arrhythmia recurrence. Ten patients had AF recurrence, two patients had left atrial flutter, and four patients had episodes of flutter as well as AF recurrence. Duration of episodes of AF after ablation gradually decreased over the follow-up period. Conclusions:,Regional ablation at the anatomic sites of the left atrial GP can be safely performed and enables maintenance of sinus rhythm in 71% of patients with paroxysmal AF for a 12-month period. (PACE 2010; 33:1231,1238) [source] Relationship Between Abnormal Microvolt T-Wave Alternans and Poor Glycemic Control in Type 2 Diabetic PatientsPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 10 2007GIULIO MOLON M.D. Background:Abnormal microvolt T-wave alternans (TWA) predicts the risk of ventricular arrhythmias and sudden cardiac death. Although type 2 diabetes is associated with an increased risk of these events, there is a dearth of available data on microvolt TWA measurements in type 2 diabetic populations. Methods:We studied 59 consecutive type 2 diabetic outpatients without manifest cardiovascular disease (CVD) and 35 non-diabetic controls who were matched for age, sex, and blood pressure values. Microvolt TWA analysis was performed non-invasively using the CH-2000 system during a sub-maximal exercise with the patient sitting on a bicycle ergometer. Results:The frequency of abnormal TWA was significantly higher in diabetic patients than in controls (25.4 vs 5.7%; P < 0.01). Among diabetic patients, those with abnormal TWA (n = 15) had remarkably higher hemoglobin A1c (HbA1c) (8.1 ± 0.9 vs 7.1 ± 0.8%, P < 0.001) and slightly smaller time-domain heart rate variability parameters (i.e., RMSSD, root mean square of difference of successive R-R intervals) than those with normal TWA (n = 44). Gender, age, body mass index, lipids, blood pressure values, cigarette smoking, diabetes duration, microvascular complication status, QTc interval, and current use of medications did not significantly differ between the groups. In multivariate regression logistic analysis, HbA1c (OR 13.6, 95% CI 2.0,89.1; P = 0.0076) predicted abnormal TWA independent of RMSSD values and other potential confounders. Conclusions:Our findings suggest that abnormal TWA is a very common condition (,25%) among people with type 2 diabetes without manifest CVD and is closely correlated to glycemic control. [source] Assessment of Noise in Digital ElectrocardiogramsPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2002VELISLAV BATCHVAROV BATCHVAROV, V., et al.: Assessment of Noise in Digital Electrocardiograms. Technically related noise in 12-lead ECGs recorded with ambulatory recorders has never been systematically compared with that in ECGs recorded with conventional ECGs. This study compared serial 10-second ECGs obtained in ten healthy men, age 22,45 years, who were recorded in the supine resting position using a (1) MAC VU recorder, (2) digital ambulatory SEER MC recorder with a Multi-Link detachable ECG cable, and (3) digital ambulatory SEER MC recorder with a light ambulatory ECG cable. In each ECG, averaged sinus rhythm cycles of the entire recording were realigned with the native signal and subtracted. The resulting "residuum" was quantified by computing its standard deviation and root mean square of successive differences (RMSSD). While the RMSSD residuum values were significantly lower with the MAC VU recorder (6.27 ± 0.98 ,V) than with the SEER MC recorder with either ECG cables (7.29 ± 1.31 and 7.17 ± 1.31 ,V, P < 0.003 and p < 0.02), the difference was practically negligible and there was no detectable difference in the standard deviation residuum values. The study concludes that valid ECG investigations of serial ECG testing may be conducted using the ambulatory SEER MC recorders providing the biological sources of ECG noise are controlled. The available technology for noise assessment suggests that studies involving advanced analysis of serial ECGs (e.g., of drug related changes), should incorporate objective characterisation of ECG quality. [source] Measurement and analysis of truck transport vibration levels and damage to packaged tangerines during transitPACKAGING TECHNOLOGY AND SCIENCE, Issue 4 2005Bundit Jarimopas Abstract The purpose of this study was to measure the vibration levels in commercial truck shipments in Thailand and observe the effects on packaged fruit. The study measured the vibration levels in two of the most commonly used truck types to ship packaged goods as a function of road condition and vehicle speed. The suspension type on the trailers studied was leaf-spring. The results of damage to packaged tangerine fruit as a function of location in the payload are also presented. The data presented in this study will assist product and package designers to reduce damage in transit. The results showed that vibration levels increased with speed and as a result of road condition. Analysis of variance indicated that three controlling factors, road surface, truck speed and truck type, significantly affected (p , 0.05) peak PSD, PSD* (root mean square) over the frequency range 2,5,Hz, and fruit damage. As expected, based on previous work, an increase in truck speed resulted in an increase in vibration levels and damage to packaged fruit. The laterite road condition produced the highest vibration level for a given truck and travelling speed followed by concrete highway and asphalt road conditions. Fruit damage was found to be greatest in the uppermost container for every combination of road, truck type and travelling speed, which also corresponded to the highest vibration levels recorded. The results showed that a significant amount of damage can occur on unpaved roads (laterite), while the packages are transported from farms and harvesting areas to regional truck terminals. Damage on asphalt road conditions was minimal. This paper provides an updated history of measured and quantified levels of vibration for these specific trucks and road conditions. Copyright © 2005 John Wiley & Sons, Ltd. [source] Impact of nitridation on structural and optical properties of MOVPE-grown m-plane GaN layers on LiAlO2PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009C. Mauder Abstract In this paper, we investigate the influence of the nitridation of LiAlO2 substrates on the growth of m-plane (1-100) GaN layers by metal-organic vapour phase epitaxy (MOVPE). Before thin film deposition, we performed an in-situ substrate pretreatment by exposing the wafer to NH3 for different times between no pretreatment and 300 s. The properties of subsequently grown layers show a significant dependency on this nitridation step. We find that this procedure is essential for obtaining pure m-plane GaN films and has a beneficial effect on the X-ray rocking curve (XRC) full width at half maximum (FWHM) value, which decreases by almost two orders of magnitude. Deposited layers with NH3 pretreatment also exhibit much smoother surfaces with a reduction of the root mean square (RMS) roughness value from ,20 to ,6 nm. Additionally, the nitridation greatly increases the GaN band edge emission intensity in room temperature (RT) photoluminescence (PL) spectroscopy. Furthermore, we compare the sensitivity of the substrate against water for uncoated LiAlO2 wafers with and without nitridation process. While the untreated surface shows a clear roughening when dipped into de-ionized (DI) water for 5 min, we can see no significant impact on the nitridated substrate surface. This indicates a change in surface composition which protects the sensitive substrate surface and provides good conditions for the nucleation of high-quality m-plane GaN films. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Simple Relationship for Predicting Impact Sensitivity of Nitroaromatics, Nitramines, and NitroaliphaticsPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 2 2010Hossein Keshavarz, Mohammad Abstract This paper describes the development of a simple model for predicting the impact sensitivity of nitroaromatics, benzofuroxans, nitroaromatics with ,-CH, nitramines, nitroaliphatics, nitroaliphatics containing other functional groups, and nitrate energetic compounds using their molecular structures. The model is optimized using a set of 86 explosives for which different structural parameters exist. The model is applied to a test set of 120 explosives from a variety of the mentioned chemical families in order to confirm the reliability of a new method. Elemental composition and two specific structural parameters, that can increase or decrease impact sensitivity, would be needed in this new scheme. The predicted impact sensitivities for both sets have a root mean square (rms) of deviation from experiment of 23,cm, which shows good agreement with respect to the measured values as compared to the best available empirical correlations. [source] Genetic influences on heart rate variability at rest and during stressPSYCHOPHYSIOLOGY, Issue 3 2009Xiaoling Wang Abstract We tested whether the heritability of heart rate variability (HRV) under stress is different from rest and its dependency on ethnicity or gender. HRV indexed by root mean square of successive differences (RMSSD) and high-frequency (HF) power was measured at rest and during 3 stressors in 427 European and 308 African American twins. No ethnic or gender differences were found for any measures. There was a nonsignificant increase in heritability of RMSSD (from 0.48 to 0.58) and HF (from 0.50 to 0.58) under stress. Up to 81% and 60% of the heritabilities of RMSSD and HF under stress could be attributed to genes influencing rest levels. The heritabilities due to genes expressed under stress were 0.11 for RMSSD and 0.23 for HF. The findings suggest that, independent of ethnicity and gender, HRV regulation at rest and under stress is largely influenced by the same genes with a small but significant contribution of stress-specific genetic effects. [source] Influence of Heavy Cigarette Smoking on Heart Rate Variability and Heart Rate Turbulence ParametersANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 4 2009Goksel Cagirci M.D. Background: Cigarette smoking increases the risk of cardiovascular events related with several mechanisms. The most suggested mechanism is increased activity of sympathetic nervous system. Heart rate variability (HRV) and heart rate turbulence (HRT) has been shown to be independent and powerful predictors of mortality in a specific group of cardiac patients. The goal of this study was to assess the effect of heavy cigarette smoking on cardiac autonomic function using HRV and HRT analyses. Methods: Heavy cigarette smoking was defined as more than 20 cigarettes smoked per day. Heavy cigarette smokers, 69 subjects and nonsmokers 74 subjects (control group) were enrolled in this study. HRV and HRT analyses [turbulence onset (TO) and turbulence slope (TS)] were assessed from 24-hour Holter recordings. Results: The values of TO were significantly higher in heavy cigarette smokers than control group (,1.150 ± 4.007 vs ,2.454 ± 2.796, P = 0.025, respectively), but values of TS were not statistically different between two groups (10.352 ± 7.670 vs 9.613 ± 7.245, P = 0.555, respectively). Also, the number of patients who had abnormal TO was significantly higher in heavy cigarette smokers than control group (23 vs 10, P = 0.006). TO was correlated with the number of cigarettes smoked per day (r = 0.235, P = 0.004). While LF and LF/HF ratio were significantly higher, standard deviation of all NN intervals (SDNN), standard deviation of the 5-minute mean RR intervals (SDANN), root mean square of successive differences (RMSSD), and high-frequency (HF) values were significantly lower in heavy smokers. While, there was significant correlation between TO and SDNN, SDANN, RMSSD, LF, and high frequency (HF), only HF was correlated with TS. Conclusion: Heavy cigarette smoking has negative effect on autonomic function. HRT is an appropriate noninvasive method to evaluate the effect of cigarette on autonomic function. Simultaneous abnormal HRT and HRV values may explain increased cardiovascular event risk in heavy cigarette smokers. [source] Heart Rate Variability in Patients with Essential Hyperhidrosis: Dynamic Influence of Sympathetic and Parasympathetic ManeuversANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2005Dayimi Kaya M.D. Background: Essential hyperhidrosis has been associated with an increased activity of the sympathetic system. In this study, we investigated cardiac autonomic function in patients with essential hyperhidrosis and healthy controls by time and frequency domain analysis of heart rate variability (HRV). Method: In this study, 12 subjects with essential hyperhidrosis and 20 healthy subjects were included. Time and frequency domain parameters of HRV were obtained from all of the participants after a 15-minute resting period in supine position, during controlled respiration (CR) and handgrip exercise (HGE) in sitting position over 5-minute periods in each stage. Results: Baseline values of HRV parameters including RR interval, SDNN and root mean square of successive R-R interval differences, low frequency (LF), high frequency (HF), normalized unit of high frequency (HFnu), normalized unit of low frequency (LFnu), and LF/HF ratio were identical in two groups. During CR, no difference was detected between the two groups with respect to HRV parameters. However, the expected increase in mean heart rate (mean R-R interval) did not occur in hyperhidrotic group, whereas it did occur in the control group (Friedman's P = 0.000). Handgrip exercise induced significant decrease in mean R-R interval in both groups and no difference was detected between the two groups with respect to the other HRV parameters. When repeated measurements were compared with two-way ANOVA, there was statistically significant difference only regarding mean heart rate in two groups (F = 6.5; P = 0.01). Conclusion: Our overall findings suggest that essential hyperhidrosis is a complex autonomic dysfunction rather than sympathetic overactivity, and parasympathetic system seems to be involved in pathogenesis of this disorder. [source] Effects of Right Coronary Artery PTCA on Variables of P-Wave Signal Averaged ElectrocardiogramANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2003Marco Budeus M.D. Background: P-wave signal averaged ECG has been used to detect atrial late potentials that were found in paroxysmal atrial fibrillation. Ischemia is supposed to trigger ventricular late potentials, which indicate an elevated risk for ventricular tachycardia. Preexistent ventricular late potentials measured by ventricular signal averaged ECG is supposed to be eliminated by successful PTCA. Methods: We examined the incidence of atrial late potentials in patients with a proximal stenosis of the right coronary artery and new onset of atrial fibrillation. Furthermore, we investigated the anti-ischemic effect of a successful percutaneous transluminal coronary angioplasty.(PTCA) of the right coronary artery. P-wave signal averaged ECG from 23 patients who had a PTCA of the right coronary artery (group A) were compared to age, sex, and disease-matched control subjects (group B) one day before, one day after, and one month after PTCA. Results: A new appearance of paroxysmal atrial fibrillation was presented in eight patients before PTCA (group A1) of group A. Patients with a stenosis of the right coronary artery had a significantly higher incidence of supraventricular extrasystoles in a 24-hour-Holter ECG (131.1 ± 45.4 vs 17.1 ± 18.9, P < 0.0002). The duration of the filtered P wave was longer (124.8 ± 11.9 vs 118.5 ± 10.1 ms, P < 0.04) and the root mean square of the last 20 ms (RMS 20) was significantly lower in group A than in group B (2.87 ± 1.09 vs 3.97 ± 1.12 ,V, P < 0.01). A successful PTCA caused an increase in RMS 20 (2.87 ± 1.11 vs 4.19 ± 1.19 ,V, P < 0.02) and a decrease in filtered P-wave duration (124.8 ± 11.9 vs 118.4 ± 10.4 ms, P < 0.04). Preexistent atrial late potentials were found among 15 patients before PTCA. After successful PTCA only 3 out of 15 patients were affected (P < 0.0004) after one day, as well as after one month. All patients with a history of atrial fibrillation did not suffer from an arrhythmic recurrence within the following six months after successful PTCA. Conclusion: A stenosis of the right coronary artery is associated with atrial late potentials. A successful PTCA of the right coronary artery eliminates preexistent atrial late potentials and may reduce the risk of atrial fibrillation. [source] Ethnic (Black-White) Contrasts in 24-Hour Heart Rate Variability in Male Adolescents with High and Low Blood Pressure: The Bogalusa Heart StudyANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 3 2000Elaine M. Urbina M.D. Background: Heart rate variability (HRV) has been used to study autonomic effects on the heart. The time-domain measure RMSSD (root mean square of successive differences) represents high frequency (HF) changes in HRV reflecting parasympathetic nervous system activity (PS). The frequency-domain ratio of low to high power (LF/HF) represents sympathetic (SYMP) to PS balance. In adults, increased SYMP tone has been found in hypertensive as compared to normals. The present study was performed to look for differences in HRV by race and between young subjects with high and low levels of diastolic blood pressure (DBP). Methods: Subjects included 34 healthy males age 13,17 years (53% white). Half were selected with K4 DBP < 85th% for height (HT) measured twice, 3,5 years apart. Half had DBP < 15th% for HT. Subjects underwent a physical examination including BP, HT, WT, and ECG prior to Holter monitor application. HRV data was analyzed from 24-hour Holter recordings obtained during normal activity. Results: The RMSSD was lower in whites compared to blacks for day, night, and 24-hour average (P , 0.05) with day-time measurements showing the largest racial difference. This suggests increased PS tone in blacks especially with activity. The LF/HF ratio was higher in whites for all times, reaching significance during the day (all P , 0.05) suggesting SYMP predominance in whites during activity. Subjects with higher levels of DBP had lower RMSSD and higher LF/HF ratio for all times, but these did not reach statistical significance. Conclusions: There is a trend towards SYMP predominance in children with higher DBP. Healthy white adolescents exhibit increased SYMP tone compared to blacks when measured during normal daytime activity. [source] Non-destructive electrical resistivity tomography for indoor investigation: the case of Kapnikarea Church in AthensARCHAEOLOGICAL PROSPECTION, Issue 1 2008G. N. Tsokas Abstract The area inside and around the church of Kapnikarea in Athens (Greece), was explored by means of electrical resistivity tomography (ERT). ,Flat base' electrodes were used exclusively because the survey had to be fully non-destructive. The performance of ,flat base' electrodes was satisfactory, leading to inversions of small root mean square (RMS) errors and reliable subsurface images, which were checked against existing borehole logs. High-resistivity anomalies were observed beneath the floor of the church. They are attributed to possible voids, remains of ancient wells, or other man-made structures concealed under the floor of the church. The results show that ,flat base' electrodes provided the advantage of fully non-destructive geoelectrical measurements. They also show that the use of the non-destructive ERT method offers a serious alternative and a complementary method to ground-penetrating radar surveys inside existing monuments. 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