Sec Period Research Articles

Effects of Transient Cerebral Hypoperfusion on Human Auditory Brainstem Responses

Adequate cerebral blood flow perfusion is crucial to maintaining brain function. The auditory brainstem response (ABR) has been demonstrated to be the most powerful diagnostic tool for assessing auditory function. This study aimed to determine the ABR under transient cerebral hypoperfusion caused by using oscillatory lower body negative pressure (OLBNP). As chronic cerebral hypoperfusion has been associated with the prolongation of the latency of ABR waves, we hypothesized that the fluctuation of cerebral blood flow perfusion also affects this latency. As prior data showing that cerebral autoregulation is not effectively engaged when pressure fluctuations are shorter than 30 sec periods (i.e., higher than 0.03 Hz), we used the sinusoidal pattern of an 18 sec period (0.056 Hz) of 0 ~ - 40 mmHg OLBNP to induce transient cerebral hypoperfusion. Here, we measured ABR and cerebral blood flow velocity (MCAv) during 12 min of control and 12 min of OLBNP (40 cycle of 18-sec periods) in 15 subjects (3 of whom were excluded from the analysis due to an insufficient number of data for ABR). Periodical changes in cerebrovascular variables were aligned relative to each 18 sec of OLBNP cycle onset and were subdivided into three phases (phase-1: 0 ~ 6 sec, phase-2: 6 ~ 12 sec, and phase-3: 12 ~ 18 sec of OLBNP onset). For the ABR analysis, a total of 6800 individual sweeps were recorded for 12 min in the control and OLBNP conditions, and the recorded sweeps in the OLBNP condition were subdivided into three phases. We observed that OLBNP caused cyclic fluctuations of MCAv. One-way repeated-measures analysis of variance (ANOVA) and the post-hoc comparison revealed that MCAv decreased significantly in phases-1 and -2 compared to the control and phase-3 (F(3, 33) = 16.54, p < 0.001). As for the ABR data, ANOVA and the post-hoc comparison revealed that the latency of wave V of ABR at phase-2 was delayed compared to phase-1 (F(3, 33) = 3.70, p < 0.05). Moreover, the results showed that the inter-individual difference in the variance over the phase conditions of the latency of wave V was significantly related to that of cerebral blood flow (r = 0.641, p < 0.05). Our data demonstrate that the fluctuation of cerebral blood flow perfusion could lead to the prolongation of the latency of ABR waves. This suggests that the transient cerebral hypoperfusion induced by an acute orthostatic blood shift to the lower body could impair auditory function.

Heart rate change and clinical characteristics in patients with neck myoclonus: An observational study

ObjectiveThis study was conducted to evaluate heart rate (HR) change and clinical characteristics in patients with neck myoclonus (NM), a physiological motor phenomenon occurring during sleep. MethodsFor 18 consecutive patients in whom NM was confirmed from video-polysomnography, we analyzed 576 NMs. Change rate of HR at each 1 sec point towards the averaged HR in prior 5 sec period was calculated before and after all NM events. ResultsFindings show NM events as more prevalent during REM sleep than during NREM sleep (83.9% vs. 16.1%). For NM without cortical arousal in REM and NREM sleep, the respective HR increased 20 s before NM (p < 0.05); the change rate was up to 13%. For NM with cortical arousal in REM sleep, the HR increased 50 s before NM (p < 0.05); the change rate reached 18%. Three NM subjects showed abnormal vocalization or shouting during REM. Six NM subjects had excessive daytime sleepiness without sleep disorder. ConclusionHR increased before NM events, which may be associated with pathophysiology of NM. NM may possibly be associated with excessive daytime sleepiness or abnormal behaviors during REM sleep. SignificanceHR increase is associated with pathophysiology of NM and clinical symptoms.

Effect of silicon carbide, magnesium oxide as reinforcing elements and zinc sterate as binding agent in the characterization of Al functionally graded materials for automotive applications

The possibility of delivering a practically evaluated material, for the most part, relies on the oddity and the institutionalization approach. In this novel work, we moved toward an efficient assembling strategy where 100µ high stimulated ball milled (MM 500) powders are exposed to steadily applied to a minimal burden containing compaction and launch process promptly pursued by sintering in a rounded heater with ASTM (G39) standardization. The processed compacts are the mix of having unadulterated aluminum of 98% virtue as network constituent and SiC and magnesium oxide going about as strengthening specialists with positive extents with the standard of blends conceptualization. The Al-SiC-MgO2 (Aluminum-Silicon carbide-magnesium oxide) samples are portrayed for their compression test as the compact crossectional area is 283.35 mm2. Furthermore, the examples are tested for hardness and we see that the hardness of the FGM is changing concerning the piece of strengthening operators and the coupling specialists included. Zinc stearate is mostly expanding the fragility in the segments though polyvinyl liquor is expanding the delicate quality of the parts. Microstructural properties of Al-SiC-MgO2 are then surveyed by an altered metallurgical magnifying instrument (GX 53) detail to plainly comprehend the stage connection between's the lattice and the fortifying components and we saw that the limits of the silicon carbide and the magnesium oxide are delicate because of less bonding between them. Tribological properties are surveyed by the pin on disc wear analyzer of model TR 201 with loads ranging from 30 to 90 N, sliding speeds 0.6–3.8 m per sec and time period from 10 min to 60 min. SEM and XRD investigation are extensively performed on these processed FGM to evaluate the dissemination of the grains along with their limits and their material formation and settlement in the crystal lattice. The outcomes of the work demonstrated that the Al-SiC-MgO2 with particular (85% + 10% + 5%) has more grounded grain limits at their expanding temperature. The distinct extents of the at long last fabricated FGM have similar extents of lattice and the strengthening components show the standardization of the actualized procedure.

Deep Learning Based on 1-D Ensemble Networks Using ECG for Real-Time User Recognition

The postmobile era will go beyond using individual smart devices and allow for user interaction by connecting various devices with sensing capabilities, such as smartphones, wearable devices, automobiles, and the Internet of Things. Wearable devices can continuously collect a variety of information on the users and their environment as the devices are worn in daily life. Because of this, real-time big data analysis technology is needed. This paper proposes a deep learning-based ensemble network model for improving the performance and overcoming the problems, which can occur on a single network. This model is designed so that the features produced by n number of single networks are combined and relearned. In addition, different parameter values are used on each single network, and the data used in the experiments are generated by the fiducial point method, which uses feature point detection, and the nonfiducial point method for periods of 1 sec and n sec. In the experiment results, in the case of fiducial point-based ECG signals, the ensemble network recognition performance shows a maximum of 0.8% higher accuracy than that of the single network. In the case of a 1 sec period nonfiducial point-based ECG signal, the ensemble network recognition performance is a minimum of 0.4% and a maximum of 1% higher than that of the single network. In the case of an n sec period, there is a maximum difference of 1.3%, and the proposed ensemble network shows better performance than the single network.

Markerless Tumor Tracking using Fast-kV Switching Dual Energy Imaging with the On-Board Imager of a Commercial Linac

Markerless tumor tracking (MTT) using template matching is currently being considered for real-time lung tumor tracking using single energy (SE) fluoroscopy. A limitation of MTT is that the tumor has to be clearly visible on images. In cases where the tumor is obscured by bony anatomy, dual energy (DE) imaging may be used to create a soft tissue only image, improving tumor visibility as well as the accuracy of MTT. The goal of this study is to evaluate MTT with fast-kV switching DE imaging using the on-board imager (OBI) of a commercial linear accelerator. Fast-kV switching DE fluoroscopy was implemented on the OBI of a commercial linac. This technique produces x-ray pulses that alternate between programmed tube voltages (ie, 120 and 60 kVp) at a rate of 15 Hz. To evaluate MTT with DE fluoroscopy, a motion phantom, consisting of a torso with embedded ribs and spine along with a cavity having lung-equivalent density, was used. Simulated tumors (5-25 mm diameter) were placed inside the lung equivalent compartment of the phantom, and then programmed to simulate breathing. Three categories of motion with varying periods were considered: static (ST), slow-motion (SM) - 5 sec period and fast-motion (FM) - 2.5 sec period. While the target was moving, fast-kV switching DE images were acquired over 360° of rotation allowing the tumor projection to overlap with varying amounts of bone. Weighted logarithmic subtraction was performed on consecutive high-low projections to produce soft tissue images. A template-based matching algorithm was then used to track target motion on both DE and SE sequences. Successful matching was defined as any instance in which the algorithm matched the template on the image. Tumor tracking coordinates were also evaluated against ground truth motion using the root-mean-squared error (RMSE). For the 5 mm target, the success rates ranged from 11-17% for SE vs. 36-63% for DE imaging, for the three types of motion considered. Because of the low success rates, RMSE were not evaluated for this target. The 10 mm target demonstrated success rates of 66-73% and 87-90% for SE and DE, respectively. The corresponding RMSE for SE were 2.7, 2.9 and 3.4 mm, while for DE they were 0.2, 1.0 and 0.5 mm, for ST, SM and FM, respectively. For the 15 mm target, SE success rates ranged from 84-89% vs. 90-94% for DE. RMSE for SE was 0.5, 2.0 and 1.4 mm vs. 0.2, 0.5, and 0.2 mm for DE for ST, SM and FM, respectively. For the larger tumors (20 and 25 mm), the success rates were > 90% for both SE and DE. RMSE for SE and DE were <1.1 mm and <0.4 mm, respectively, for all motion categories. Fast-kV switching DE imaging has been implemented on the OBI of a commercial linac. Overall, MTT with DE imaging results in higher success rates and lower RMSE than using SE imaging alone. The approach allows for the accurate tracking of small tumors where MTT fails on SE imaging due to overlapping bony anatomy.

Probabilistic seismic hazard assessment for Hanoi city

In this study, the methodology of probabilistic seismic hazard assessment proposed by Cornell and Esteva in 1968 was applied for Hanoi city, using an earthquake catalog updated until 2018 and a comprehensive seismotectonic model of the territory of Vietnam and adjacent sea areas. Statistical methods were applied for declustering the earthquake catalog, then the maximum likelihood method was used to estimate the parameters of the Gutenberg–Richter Law and the maximum magnitude for each seismic source zone. Two GMPEs proposed by Campbell &amp; Bozorgnia (2008) and Akkar et al., (2014) were selected for use in hazard analysis. Results of PSHA for Hanoi city are presented in the form of probabilistic seismic hazard maps, depicting peak horizontal ground acceleration (PGA) as well as 5-hertz (0.2 sec period) and 1-hertz (1.0 sec. period) spectral accelerations (SA) with 5-percent damping on a uniform firm rock site condition, with 10%, 5%, 2% and 0,5% probability of exceedance in 50 years, corresponding to return times of 475; 975; 2,475 and 9,975 years, respectively. The results of PSHA show that, for the whole territory of Hanoi city, for all four return periods, the predicted PGA values correspond to the intensity of VII to IX degrees according to the MSK-64 scale. As for the SA maps, for all four return periods, the predicted SA values at 1.0 s period correspond to the intensity of VI to VII, while the predicted SA values at 0.2 s period correspond to the intensity of VIII to X according to the MSK-64 scale. This is the last updated version of the probabilistic seismic hazard maps of Hanoi city. The 2019 probabilistic seismic hazard maps of Hanoi city display earthquake ground motions for various probability levels and can be applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy.

Influence of stabilization and short-term relaxation to compression generated by stocking welt

This research was carried out to investigate the influence of yarns and knitting parameters, stabilization, and relaxation processes on compression properties of knitted fabrics, used for stocking welt or other compression products. It is well-known that there is a high correlation between the mechanical properties of the fabric and its generated pressure. Also, it is proved that generated compression values decrease during the time they are being worn. In this research, it was found that course and wale density of knitted fabric, as well as tensile force values, increased after the stabilization process. Moreover, increases of linear density of core yarn (PU) of elastomeric yarn do not have direct linear influence to its generated tensile force. The results of short-term stress relaxation tests (300 sec) showed that the major alteration of the generated compression values appears during the first 100 sec period of relaxation process.

An AEM system calibration

VTEM data was collected over a ground loop laid out near Cape Naturaliste, WA. The system calibration was determined to be correct within experimental error. The current induced in the ground loop and the airborne VTEM response agree within experimental error to theoretical predictions of amplitude, shape and decay characteristics from channel 6 onwards. Because the background response of the ground dominated the early time channels, it was not possible to exactly quantify the early time calibration for Channels 1 to 5. With GPS systems fitted to the airborne loop and the helicopter, 10 bathymetry survey lines were analysed to determine the statistical variations to be expected in system geometry in ?straight and level balanced flight?. Approximately Gaussian variances found for geometry parameters imply that the VTEM system geometry for this specific system could be specified as a mean value with 95% confidence limits at 2 standard deviations. The mean geometry and 95% limits for VTEM-24 Tx-Rx assembly were: 35 (±3) m below and 22 (±4) m behind the GPS sensor on the tail of the helicopter, displaced 3 (±3) m to port. Tilted nose down at 5.5 (±6)o and tilted to starboard 1 (±6)o The VTEM geometry has been historically quoted as a nominal 40 m below the helicopter altimeter, although some reports have used a figure of 37 m. This measurement suggests that true VTEM loop altitudes are in fact somewhat higher than the numbers delivered in historic data. Correct vertical offset is critical in quantitative modelling. Further, previously modelled dips of discrete conductors may need to be adjusted by 5.5 o to be consistent with the systematic loop tilt. The loop swing in-line (distance behind helicopter) shows a small energy peak at the 12 sec pendulum frequency, plus additional effects at longer periods attributed to gradual speed variations. The loop swing from side-to-side exhibits a 20-30 sec period, identical to the sideways helicopter accelerations, and is hypothesised to be due to controlled pilot steering adjustments to keep on-line.

Oscillatory Patterns of Phase Cone Formations near to Epileptic Spikes Derived from 256-Channel Scalp EEG Data.

Our objective was to determine if there are any distinguishable phase cone clustering patterns present near to epileptic spikes. These phase cones arise from episodic phase shifts due to the coordinated activity of cortical neurons at or near to state transitions and can be extracted from the high-density scalp EEG recordings. The phase cone clustering activities in the low gamma band (30–50 Hz) and in the ripple band (80–150 Hz) were extracted from the analytic phase after taking Hilbert transform of the 256-channel high density (dEEG) data of adult patients. We used three subjects in this study. Spatiotemporal contour plots of the unwrapped analytic phase with 1.0 ms intervals were constructed using a montage layout of 256 electrode positions. Stable phase cone patterns were selected based on the criteria that the sign of the spatial gradient did not change for at least three consecutive time samples and the frame velocity was within the range of propagation velocities of cortical axons. These plots exhibited dynamical formation of phase cones which were higher in the seizure area as compared with the nearby surrounding brain areas. Spatiotemporal oscillatory patterns were also visible during ±5 sec period from the location of the spike. These results suggest that the phase cone activity might be useful for noninvasive localization of epileptic sites and also for examining the cortical neurodynamics near to epileptic spikes.

BRAIN ACTIVATION CHANGES DURING THE DELAY PERIOD IN A WORKING MEMORY TASK: NORMAL AGING-RELATED EFFECTS

Brain activation is assumed to be constant during the delay period of a delay match to sample task (DMTS). The objective was to examine the dynamic changes in brain activation (using fMRI) during a DMTS in young and older healthy subjects. There were 33 young participants (under 40 years old) and 23 older participants (over 55 years old). The study was approved by the Research Ethics Committee of the Faculty of Health Sciences in Trinity College Dublin. All participants signed informed consent before participating in study. The DMS task had 3 trial types: face-name, face and a control (scrambled images). Trials consisted of an encode phase (2s), a delay (18s) and a probe phase (4s), with a jittered inter-trial interval (6–14s). There were 75 trials (25 face-name pairs, 25 face and 25 control stimuli). The regressors for the analysis included in the first case regressors for the encoding, delay and probe periods but these were expanded to subdivide the delay period into three 6 sec period: initial, middle, and late periods. Statistical significance was set at voxel-wise threshold of p≤0.005. To correct for multiple comparisons, each cluster had a minimum size of 683μl (23 voxels) which was calculated using AlphaSim (AFNI) to get a family wise error corrected statistical significance level of p<0.05. For the young group the statistical parametric map (SPM) of the face vs control are shown in Figure 1 and with the delay period sub-divided into 3 parts in Figure 2. Similarly the face-name DMTS results are shown in Figure 3 and Figure 4 (split delay periods). In Figure 5, face vs control activation patterns seen in the older healthy groups (split delay) are seen, and Figure 6 contain the results from the face-name vs control task. The statistical maps show that during the delay period with either face or face-name stimuli, the activation pattern varied among the 3 different periods in both young and older cohorts.

Single-Cell Motility Analysis of Stimulated Diatoms using a Microchamber

Motility of diatom cells that were stimulated by irradiation with controlled visible lights were studied using a microchamber. Isolated Navicula sp. cells were deposited in a microchamber made of poly(dimethylsiloxane) in order to realize a long period observation. In the first experiment, the diatom cells were continuously observed for 60 min by an optical microscope. If the microchamber does not appropriately work, the 60 min observation should be difficult, because the cells were moved outside the observation area. In the first 20 min, the cells were irradiated by a halogen lamp. Then, the light shielded by a cut-off filter (cut-off wavelength: 550 nm) irradiated to the sample for the next 20 min. In the final 20 min, the sample was irradiated without the filter again. Brightness was kept at 500 lux for 60 min by a dimming filter to avoid effects of brightness. Then, movements of 17 individual cells were analyzed by a two-dimensional trajectory analysis software. As a result, the velocities of 12 cells were decreased while the light was shielded by the filter (20-40 min). T-test results also suggested that the velocity was significantly decreased. In the second experiments, we prepared small colonies of diatom cells in a microchamber with 12 days incubation. Then, the colonies were irradiated with a mercury lamp with three different cut filters for 100 sec period. In this experiment, we focused on inactive (stopped) cells. The cells were found to start to move after the irradiation. However, after stopping the irradiation, the velocities of the activated cells were decreased gradually. In addition, the decrease was affected by the types of the filters. Our data revealed a possibility of detailed analysis of diatom motility using the microchamber system.

Short-Term Memory Effects on Crossing the Boundary: Discrimination between Large and Small Quantities in Angelfish (Pterophyllum scalare).

Rudimentary quantification abilities are found in numerous animal species and in human infants all demonstrating the ability to discriminate between quantities differing in numerical size. An open question is whether individuals rely on different underlying systems to discriminate between large (analogue magnitude system (AMS) for number of items exceeding 3) and small quantities (object-file system (OFS) for number of items below 4), or they use only one system (AMS) for the entire number range. The two-system hypothesis has been supported by finding reduced ability to discriminate between quantities that cross the large-small boundary in several species. Recently, the role of cognitive representation, i.e., memory, in quantity discrimination has also been recognized. Here, we investigated whether angelfish can discriminate quantities across the boundary under two memory conditions. In a binary choice test, single angelfish were allowed to see groups (shoals) of conspecifics of different numerical size on the two sides of their test tank. In Experiment 1, their choice was recorded after a 2-sec retention interval during which shoal size information was unavailable. Angelfish were able to discriminate the larger shoal across the boundary when the shoals differed by a 2:1 or higher ratio, but not when the ratio was lower. In Experiment 2, however, with a 15-sec retention interval, angelfish could only detect a four-fold difference in ratio but failed to detect a three- or a two-fold difference across the boundary. These results suggest that angelfish can remember smaller differences for a short (2 sec) but not for a longer (15 sec) period. Together with previous findings, the current results support the idea that angelfish use two distinct systems for representing quantity, but they may recruit the AMS even for the small number range under some circumstances, e.g., when higher memory demand is imposed by a greater retention interval.

Site Classification and Design Response Spectra for Seismic Code Provisions - (II) Proposal

In the companion paper (I - Database and Site Response Analyses), site-specific response analyses were performed at more than 300 domestic sites. In this study, a new site classification system and design response spectra are proposed using results of the site-specific response analyses. Depth to bedrock (H) and average shear wave velocity of soil above the bedrock () were adopted as parameters to classify the sites into sub-categories because these two factors mostly affect site amplification, especially for shallow bedrock region. The 20 m of depth to bedrock was selected as the initial parameter for site classification based on the trend of site coefficients obtained from the site-specific response analyses. The sites having less than 20 m of depth to bedrock (H1 sites) are sub-divided into two site classes using 260 m/s of while the sites having greater than 20 m of depth to bedrock (H2 sites) are sub-divided into two site classes at equal to 180 m/s. The integration interval of 0.4 ~ 1.5 sec period range was adopted to calculate the long-period site coefficients () for reflecting the amplification characteristics of Korean geological condition. In addition, the frequency distribution of depth to bedrock reported for Korean sites was also considered in calculating the site coefficients for H2 sites to incorporate sites having greater than 30 m of depth to bedrock. The relationships between the site coefficients and rock shaking intensity were proposed and then subsequently compared with the site coefficients of similar site classes suggested in other codes.

SU‐F‐T‐518: Development and Characterization of a Gated Treatment System Implemented with An In‐House Optical Tracking System and the Elekta Response Interface

Purpose:To report the development and characterization of the first in‐house gating system implemented with an optical tracking system (OTS) and the Elekta Response™ interface.Methods:The Response™ connects a patient tracking system with a linac, enabling the tracking system to control radiation delivery. The developed system uses an in‐house OTS to monitor patient breathing. The OTS consists of two infrared‐based cameras, tracking markers affixed on patient. It achieves gated or breath‐held (BH) treatment by calling beam ON/OFF functions in the Response™ dynamic‐link library (DLL). A 4D motion phantom was used to evaluate its dosimetric and time delay characteristics. Two FF‐ and two FFF‐IMRT beams were delivered in non‐gated, BH and gated mode. The sinusoidal gating signal had a 6 sec period and 15 mm amplitude. The duty cycle included 10%, 20%, 30% and 50%. The BH signal was adapted from the sinusoidal wave by inserting 15 sec BHs. Each delivery was measured with a 2D diode array (MapCHECK™) and compared with the non‐gated delivery using gamma analysis (3%). The beam ON/OFF time was captured using the service graphing utility of the linac.Results:The gated treatments were successfully delivered except the 10% duty cycle. The BH delivery had perfect agreement (100%) with non‐gated delivery; the agreement of gated delivery decreased from 99% to 88% as duty cycle reduced from 50% to 20%. The beam on/off delay was on average 0.25/0.06 sec. The delivery time for the 50%, 30% and 20% duty cycle increased by 29%, 71% and 139%, respectively. No dosimetric or time delay difference was noticed between FF‐ and FFF‐IMRT beams.Conclusion:The in‐house gating system was successfully developed with dosimetric and time delay characteristics in line with published results for commercial systems. It will be an important platform for further research and clinical development of gated treatment.

TH‐CD‐209‐07: Preliminary Experimental Comparison of Spot‐ and Continuous Line Scanning with Or Without Rescanning for Gated Proton Therapy

Purpose:We aim to compare the performance of discrete spot‐ or continuous line scanning combined with rescanning in mitigating residual organ motion during gated proton therapy treatments.Methods:The Quasar respiratory phantom was used to move a 2D scintillation detector on a linear trajectory with sinusoidal motion pattern (sin4), 20 mm peak‐to‐peak amplitude and 5 sec period. Its motion was monitored using a customized solution based on optical tracking technology. We compared spot and line scanning plans for a monoenergetic 150 MeV circular field, 50.4 mm radius at isocenter. Transverse dose distributions at 13 cm depth in PMMA (15.47 mm water equivalent) were measured to compare three options for motion mitigation: rescanning (10× factor), gating and their combination. The gating window was centered in the trajectory plateau to simulate end‐exhale gated treatment in presence of 2 mm and 4 mm residual motion, parallel or perpendicular to the primary scanning direction.Results:When the target moves perpendicular to the primary scanning direction, large dose deviations are measured (γ3%/3mm=47%) without mitigation techniques. Beam gating combined with rescanning restores target coverage (γ3%/3mm=91%). For parallel target motion, observed dose distortions in the non‐compensated irradiation are smaller (γ3%/3mm=77%). Beam gating alone recovers the 100% gamma pass‐rate at 3%/3mm. Continuous line scanning reduces delivery time by up to 60% with respect to discrete spot scanning in presence of motion mitigation, and improves homogeneity when rescanning is applied (up to 20%, perpendicular motion, 4 mm residual motion).Conclusion:The direction of motion has a large impact on the target dose coverage. Nevertheless, even in the worst case scenario, gating combined with rescanning could mitigate the impact of motion on dose deposition. Moreover, continuous line rescanning improves the robustness against residual motion in the gating window.This study has received funding from the European Community's Seventh Framework Programme (FP7/2007–2013) under grant agreement n.290605 (PSI‐FELLOW/COFUND) and ‘Giuliana and Giorgio Stefanini Foundation’

MO-FG-BRA-02: A Feasibility Study of Integrating Breathing Audio Signal with Surface Surrogates for Respiratory Motion Management

Purpose: Tracking the surrogate placed on patient skin surface sometimes leads to problematic signals for certain patients, such as shallow breathers. This in turn impairs the 4D CT image quality and dosimetric accuracy. In this pilot study, we explored the feasibility of monitoring human breathing motion by integrating breathing sound signal with surface surrogates. Methods: The breathing sound signals were acquired though a microphone attached adjacently to volunteer's nostrils, and breathing curve were analyzed using a low pass filter. Simultaneously, the Real-time Position Management™ (RPM) system from Varian were employed on a volunteer to monitor respiratory motion including both shallow and deep breath modes. The similar experiment was performed by using Calypso system, and three beacons taped on volunteer abdominal region to capture breath motion. The period of each breathing curves were calculated with autocorrelation functions. The coherence and consistency between breathing signals using different acquisition methods were examined. Results: Clear breathing patterns were revealed by the sound signal which was coherent with the signal obtained from both the RPM system and Calypso system. For shallow breathing, the periods of breathing cycle were 3.00±0.19 sec (sound) and 3.00±0.21 sec (RPM); For deep breathing, the periods were 3.49± 0.11 sec (sound) and 3.49±0.12 sec (RPM). Compared with 4.54±0.66 sec period recorded by the calypso system, the sound measured 4.64±0.54 sec. The additional signal from sound could be supplement to the surface monitoring, and provide new parameters to model the hysteresis lung motion. Conclusion: Our preliminary study shows that the breathing sound signal can provide a comparable way as the RPM system to evaluate the respiratory motion. It's instantaneous and robust characteristics facilitate it possibly to be a either independently or as auxiliary methods to manage respiratory motion in radiotherapy.

Metabolic Responses to Whole-Body Vibration Varying in Frequency and Amplitude

Whole-body vibration (WBV) has been shown to provide neurological potentiation, thereby enhancing muscular activity. To date, how WBV might influence energy metabolism has not been fully elucidated. PURPOSE: This study was undertaken to assess the effect of various vibratory loads on metabolic responses during WBV and subsequent aerobic exercise. METHODS: Sixteen subjects (21.0±2 yr) including eight men and eight women underwent six WBV sessions that differed in frequency (e.g., 30-Hz, 40-Hz, and 50-Hz) and amplitude (e.g., 1-2 mm and 2-3 mm) in a randomized order. In each WBV session, subjects performed 10 sets of 10 body weight squats with each set lasting 30 sec and 1-min rest period between sets on a vibration platform with a vibration load that represented one of the six frequency-amplitude combinations. Each vibration treatment was immediately followed by 20 min of a constant load cycle exercise at 65% VO2peak. Oxygen uptake (VO2) and respiratory exchange ratio (RER) were measured throughout WBV and subsequent exercise. The average VO2 and RER of both WBV and exercise were analyzed using 2-way (frequency × amplitude) repeated measure ANOVA followed by pairwise comparisons involving Bonferroni correction. RESULTS: During WBV, VO2 demonstrated a progressive increase as a function of vibration frequency and amplitude. A significant main effect of amplitude was observed for VO2 in l·min-1 (F=6.326, p=0.02) and ml·kg-1·min-1 (F=5.497, p=0.03). The highest VO2 occurred at 50-Hz and 2-3 mm (e.g., 13.1±2.4 ml·kg-1·min-1). During subsequent exercise, VO2 responded similarly to that seen in WBV, and there were trends (p = 0.08-0.10) towards a greater VO2 at higher frequencies or amplitudes. No effects of vibration frequency or amplitude on RER were found during either WBV or subsequent exercise. CONCLUSIONS: WBV can augment metabolic responses in a load-dependent manner when administered concurrently with body-weight squats. Such a stimulating effect seems to persist during aerobic exercise that commences immediately after WBV.

Abstract 251: Measuring the Association of CPR Quality Metrics and Intra-Arrest End-Tidal Carbon Dioxide

Background: End-tidal carbon dioxide (ETCO 2 ) is an indicator of blood flow during low-flow states such as during CPR delivery. Given that cardiac arrest survival is sensitive to CPR quality, ETCO2 might serve to guide CPR during clinical care. ETCO 2 has been shown to be a useful indicator of CPR quality in laboratory arrest models, however, there is a lack of clinical data assessing this relationship in humans. Objectives: To determine the association between quantitative CPR performance and intra-arrest ETCO2 in a time-based analysis of clinical resuscitation events. Methods: In this single center retrospective study we collected ETCO 2 data and time-synchronized CPR quality metrics using CPR-recording defibrillators (MRx QCPR, Philips Healthcare) during cardiac arrest events between 08/2007-06/2012. For each case, mean ETCO 2 for each 30 sec segment of CPR was calculated manually by averaging the peaks of each capnographic waveform. CPR 30 sec segments were divided into tertiles based on rate and depth, and combined to form nine groups representing combinations of CPR performance. A mixed-effect regression of mean ETCO 2 with the nine CPR combinations was performed using shallow depth and slow rate as the reference category. Results: Of the 54 arrest events with both CPR quality metrics and ETCO 2 waveform data, we extracted 992 30 sec blocks that had compression pauses &lt; 5 sec. Deep compression depth coupled with a slow, medium or fast rate and a medium depth coupled with a fast rate produced statistically significant higher ETCO 2 values than the reference category (see figure). Conclusions: Greater compression rate and depth are associated with higher mean ETCO 2 during the same 30 sec period of time. This relationship suggests a physiologic response to CPR quality as detected via ETCO 2 measurement. The potential clinical use of ETCO2 to guide CPR requires further investigation.

Effects of 5‐fluorouracil and scopolamine in three variations of the autoshaping procedure

The experiments in the present study examined whether 5‐ fluorouracil (5‐FU) or scopolamine would be more disruptive to the Instrumental or Pavlovian conditioning aspects of the autoshaping procedure. We compared the effects of saline, scopolamine or 5‐FU in the traditional autoshaping procedure with both Pavlovian and Instrumental components (autoshaping‐PI) to an autoshaping procedure with predominantly Instrumental contingencies (autoshaping‐I) and an autoshaping procedure with predominantly Pavlovian associations (autoshaping‐P). Mice were presented a tone on a variable‐time schedule, with the tone remaining on for 6 sec or until a nose‐poke response occurred (autoshaping‐PI; autoshaping‐I). If no response was made during the tone, the dipper was presented at the end of the 6 sec period (autoshaping‐PI; autoshaping‐P). Mice acquired autoshaped responses in all three procedures, although acquisition occurred more quickly in autoshaping‐PI. Responding in the autoshaping‐PI and autoshaping‐I procedures revealed more disruptions after injections of 5‐FU and scopolamine demonstrating either the increased sensitivity of these two procedures to drug effects.

Joint inversion of Rayleigh wave phase velocity and ellipticity using USArray: Constraining velocity and density structure in the upper crust

Rayleigh wave ellipticity, or H/V ratio, observed on the surface is particularly sensitive to shallow earth structure. In this study, we jointly invert measurements of Rayleigh wave H/V ratio and phase velocity between 24–100 and 8–100 sec period, respectively, for crust and upper mantle structure beneath more than 1000 USArray stations covering the western United States. Upper crustal structure, in particular, is better constrained by the joint inversion compared to inversions based on phase velocities alone. In addition to imaging Vs structure, we show that the joint inversion can be used to constrain Vp/Vs and density in the upper crust. New images of uppermost crustal structure (&lt;3 km depth) are in excellent agreement with known surface features, with pronounced low Vs, low density, and high Vp/Vs anomalies imaged in the locations of several major sedimentary basins including the Williston, Powder River, Green River, Denver, and San Juan basins. These results demonstrate not only the consistency of broadband H/V ratios and phase velocity measurements, but also that their complementary sensitivities have the potential to resolve density and Vp/Vs variations.