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Pulse transit time

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https://www.readbyqxmd.com/read/28339132/formation-of-endohedral-metallofullerene-emf-ions-of-mnc2m-m%C3%A2-%C3%A2-la-y-n%C3%A2-%C3%A2-%C3%A2-6-50%C3%A2-%C3%A2-%C3%A2-2%C3%A2-m%C3%A2-%C3%A2-%C3%A2-194-in-the-laser-ablation-process-with-graphene-as-precursor
#1
Xianglei Kong, Xiaodi Bao
RATIONALE: Graphene has been found to be a versatile precursor for the generation of mono-endohedral metallofullerenes (EMFs) of alkali and alkali earth metal atoms. Thus, it is important to investigate whether graphene is also a good precursor for the generation of EMFs including multi-metal atoms or some transition metal atoms. METHODS: Experiments were performed on a 7.0 T Fourier transform ion cyclotron resonance (FT ICR) mass spectrometer. Laser ablation mass spectra were obtained by laser irradiation on mixtures of graphene and LaCl3 , YCl3 or HAuCl4 on a stainless steel plate...
March 24, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28336426/sar-simulations-safety
#2
Thomas M Fiedler, Mark E Ladd, Andreas K Bitz
At ultra-high fields, the assessment of radiofrequency (RF) safety presents several new challenges compared to low-field systems. Multi-channel RF transmit coils in combination with parallel transmit techniques produce time-dependent and spatially varying power loss densities in the tissue. Further, in ultra-high-field systems, localized field effects can be more pronounced due to a transition from the quasistationary to the electromagnetic field regime. Consequently, local information on the RF field is required for reliable RF safety assessment as well as for monitoring of RF exposure during MR examinations...
March 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28328013/validation-of-surface-to-volume-ratio-measurements-derived-from-oscillating-gradient-spin-echo-on-a-clinical-scanner-using-anisotropic-fiber-phantoms
#3
Gregory Lemberskiy, Steven H Baete, Martijn A Cloos, Dmitry S Novikov, Els Fieremans
A diffusion measurement in the short-time surface-to-volume ratio (S/V) limit (Mitra et al., Phys Rev Lett. 1992;68:3555) can disentangle the free diffusion coefficient from geometric restrictions to diffusion. Biophysical parameters, such as the S/V of tissue membranes, can be used to estimate microscopic length scales non-invasively. However, due to gradient strength limitations on clinical MRI scanners, pulsed gradient spin echo (PGSE) measurements are impractical for probing the S/V limit. To achieve this limit on clinical systems, an oscillating gradient spin echo (OGSE) sequence was developed...
March 22, 2017: NMR in Biomedicine
https://www.readbyqxmd.com/read/28327464/monte-carlo-simulations-of-time-of-flight-pet-with-double-ended-readout-calibration-coincidence-resolving-times-and-statistical-lower-bounds
#4
Stephen E Derenzo
This paper demonstrates through Monte Carlo simulations that a practical positron emission tomograph with (1) deep scintillators for efficient detection, (2) double-ended readout for depth-of-interaction information, (3) fixed-level analog triggering, and (4) accurate calibration and timing data corrections can achieve a coincidence resolving time (CRT) that is not far above the statistical lower bound. One Monte Carlo algorithm simulates a calibration procedure that uses data from a positron point source. Annihilation events with an interaction near the entrance surface of one scintillator are selected, and data from the two photodetectors on the other scintillator provide depth-dependent timing corrections...
March 22, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28324936/a-preliminary-study-on-multi-wavelength-ppg-based-pulse-transit-time-detection-for-cuffless-blood-pressure-measurement
#5
Jing Liu, Yuan-Ting Zhang, Xiao-Rong Ding, Wen-Xuan Dai, Ni Zhao
Pulse transit time (PTT) has been widely studied as an index of blood pressure (BP) changes. In recent years, some prototypes of PTT-based wearable BP measurement devices have been developed, which can relieve users from the discomfort caused by the inflating cuff used in auscultatory and oscillometric BP measurement techniques. However, in the common practice for PTT detection, multi-site sensor implementation on human body is required, making it difficult for the integration of wearable devices. Since multi-wavelength (MW) photoplethysmogram (PPG) signals carry blood pulsation information of different blood vessels embedded in different skin depths, the time difference between different wavelength PPG signals collected at the same body site can be treated as a special PTT on a short length of blood vessels beneath the skin...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28315390/quantifying-the-dynamic-density-driven-convection-in-high-permeability-packed-beds
#6
Ying Teng, Lanlan Jiang, Yingting Fan, Yu Liu, Dayong Wang, Abuliti Abudula, Yongchen Song
The density driven convection phenomenon is expected to have a significant and positive role in CO2 geological storage capacity and safety. The onset and development of density-driven convective on the core scale is critical to understand the mass transfer mechanism. In this paper, laboratory experiments were conducted to investigate the density-driven convective in a vertical tube. The deuterium oxide (D2O)/manganese chloride (MnCl2) water solution in water or brine were as an analog for CO2-rich brine in original brine...
March 14, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28303943/increased-chemical-weathering-during-the-deglacial-to-mid-holocene-summer-monsoon-intensification
#7
Pavan Miriyala, N P Sukumaran, B Nagender Nath, P B Ramamurty, A V Sijinkumar, B Vijayagopal, V Ramaswamy, Tyson Sebastian
Chemical weathering and the ensuing atmospheric carbon dioxide consumption has long been considered to work on geological time periods until recently when some modelling and natural records have shown that the weathering-related CO2 consumption can change at century to glacial-interglacial time scale. Last glacial to interglacial transition period is a best test case to understand the interplay between Pco2-temperature-chemical weathering when a pulse of rapid chemical weathering was initiated. Here we show, from a high resolution 54 ka record from the Andaman Sea in the northern Indian Ocean, that the chemical weathering responds to deglacial to mid-Holocene summer monsoon intensification in the Myanmar watersheds...
March 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28287159/double-wall-carbon-nanotube-hybrid-mode-locker-in-tm-doped-fibre-laser-a-novel-mechanism-for-robust-bound-state-solitons-generation
#8
Maria Chernysheva, Anastasia Bednyakova, Mohammed Al Araimi, Richard C T Howe, Guohua Hu, Tawfique Hasan, Alessio Gambetta, Gianluca Galzerano, Mark Rümmeli, Aleksey Rozhin
The complex nonlinear dynamics of mode-locked fibre lasers, including a broad variety of dissipative structures and self-organization effects, have drawn significant research interest. Around the 2 μm band, conventional saturable absorbers (SAs) possess small modulation depth and slow relaxation time and, therefore, are incapable of ensuring complex inter-pulse dynamics and bound-state soliton generation. We present observation of multi-soliton complex generation in mode-locked thulium (Tm)-doped fibre laser, using double-wall carbon nanotubes (DWNT-SA) and nonlinear polarisation evolution (NPE)...
March 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28281031/pulse-transit-time-as-a-tool-to-characterize-obstructive-and-central-apneas-in-children
#9
Lucie Griffon, Alessandro Amaddeo, Jorge Olmo Arroyo, Rossana Tenconi, Serena Caggiano, Sonia Khirani, Brigitte Fauroux
PURPOSE: The characterization of apneas during polysomnography (PSG) as obstructive or central is a key element of a sleep study. Pulse transit time (PTT) has demonstrated its potential as a noninvasive surrogate marker for inspiratory efforts. The aim of the study was to assess the ability of PTT to classify apneas as central or obstructive, as compared to respiratory inductance plethysmography (RIP) in children. METHODS: Overnight PSG with simultaneous PTT recording was performed on 11 consecutive children (mean age 8...
March 9, 2017: Sleep & Breathing, Schlaf & Atmung
https://www.readbyqxmd.com/read/28269566/dual-modality-arterial-pulse-monitoring-system-for-continuous-blood-pressure-measurement
#10
Wen-Xuan Dai, Yuan-Ting Zhang, Jing Liu, Xiao-Rong Ding, Ni Zhao
Accurate and ambulatory measurement of blood pressure (BP) is essential for efficient diagnosis, management and prevention of cardiovascular diseases (CVDs). However, traditional cuff-based BP measurement methods provide only intermittent BP readings and can cause discomfort with the occlusive cuff. Although pulse transit time (PTT) method is promising for cuffless and continuous BP measurement, its pervasive use is restricted by its limited accuracy and requirement of placing sensors on multiple body sites...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28269221/cuff-pressure-induced-pat-changes-modelling-and-experimental-verification-towards-calibration-of-blood-pressure-surrogates
#11
Erik Bresch, Lars Schmitt, Dennis De Matteis, Jens Muehlsteff
Arterial Blood Pressure (ABP) is one of the most often measured vital parameters in daily clinical practice. State-of-the-Art non-invasive ABP measurement technologies have obvious limitations and are still mainly based on uncomfortable techniques by complete or partial occlusions of arteries. Additionally, embodiments are bulky, difficult to apply for the layman, or provide only intermittent measurements. We have been investigating the pulse arrival time (PAT) and pulse transit time (PTT) methodology for unobtrusive blood pressure (BP) measurements...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28269220/using-multiple-placements-of-accelerometers-to-measure-cardiovascular-pulse-transit-times
#12
Natalie Kurgan Canino, Ruisheng Wang, Charles J Robinson
To measure pulse transit times (PTT) and calculate pulse wave velocities (PWV), tri-axial and uniaxial accelerometers were placed in groups of 2 to 4 over the manubrium, xiphoid process, forehead, wrist and ankle, and/or over the carotid, femoral, and posterior auricular arteries in 11 consented supine subjects. Signals were sampled at 1 kHz and filtered. Radial vectors were calculated from the tri-axial measurements. A 3-lead ECG was simultaneously collected over the same 180 s window, as well as respiratory rate...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28269219/comparison-of-methods-for-the-evaluation-of-nibp-from-pulse-transit-time
#13
L Peter, N Noury, M Cerny, I Nykl
Non-invasive blood pressure measurement (NIBP) is one of the most discussed topic in cardiovascular medicine. Currently continuous measurement of blood pressure is possible by invasive methods, which makes the measurement impractical for Doctors and uncomfortable for the patients. It is possible to use special devices to measure blood pressure noninvasively continuously but there are still some problems with long time monitoring and comfort for patient. Physiologically there is connection between electrical and mechanical heart functions, propagation of pulse wave and blood pressure value...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28269218/a-pulse-transit-time-based-fusion-method-for-the-noninvasive-and-continuous-monitoring-of-respiratory-rate
#14
Xiao-Rong Ding, Yuan-Ting Zhang, Hon Ki Tsang, Walter Karlen
The purpose of this study was to investigate whether pulse transit time (PTT) can be used for continuous monitoring of respiratory rate (RR). We derived PTT from the electrocardiogram and photoplethysmogram obtained from 42 recordings of CapnoBase, a publicly available benchmark data set for validating respiratory related measurements. The number of breaths in a minute (RR#) was estimated from the heart rate interval (HRI), pulse rate interval (PRI), and from PTT. In addition, to improve the estimation reliability, we investigated a fusion of the three HRI, PRI and PTT derived estimations...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28269047/pulse-transit-time-and-heart-rate-variability-in-sleep-staging
#15
Sobhan Salari Shahrbabaki, Beena Ahmed, Thomas Penzel, Dean Cvetkovic
This paper presents a new and robust algorithm for detection of sleep stages by using the lead I of the Electrocardiography (ECG) and a fingertip Photoplethysmography (PPG) sensor, validated using multiple overnight PSG recordings consisting of 20 human subjects (9 insomniac and 11 healthy). Heart Rate Variability (HRV) and Pulse Transit Time (PTT) biomarkers which were extracted from ECG and PPG biosignals then employed to extract features. Distance Weighted k-Nearest Neighbours (DWk-NN) was used as classifier to differentiate sleep epochs...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28268983/double-sensor-complementary-placement-method-to-reduce-motion-artifacts-in-ppg-using-fast-independent-component-analysis
#16
Frank P-W Lo, Max Q-H Meng
A novel sensor placement method for better removal of motion artifacts (MA) from photoplethysmography (PPG) signal using Fast Independent Component Analysis (ICA) is proposed in this paper. The method enhances the determination of pulse transit time (PTT) of PPG signals. The design makes use of double reflectance mode based PPG probes, which are placed complementary to each other and on the two sides of a single finger. Furthermore, a novel indicator denoted as Separating Factor is proposed as well. It helps evaluating the performance of ICA with different sensors configuration...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28268912/photoplethysmography-derivatives-and-pulse-transit-time-in-overnight-blood-pressure-monitoring
#17
Sobhan Salari Shahrbabaki, Beena Ahmed, Thomas Penzel, Dean Cvetkovic
Overnight continuous blood pressure measurement provides simultaneous monitoring of blood pressure and sleep architecture. By this means, we are able to investigate whether different sleep events are associated to blood pressure fluctuations. In this paper, we used the Pulse Transit Time (PTT) to develop and evaluate functions for measurement of blood pressure. We focused on the first and second derivatives of fingertip Photoplethysmography (PPG) recordings to detect PPG critical points. By applying R wave of ECG and PPG critical points, we created two PTT-based models for estimation of systolic and diastolic blood pressure (SBP and DBP)...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28268403/cuff-less-ppg-based-continuous-blood-pressure-monitoring-a-smartphone-based-approach
#18
Aman Gaurav, Maram Maheedhar, Vijay N Tiwari, Rangavittal Narayanan
Cuff-less estimation of systolic (SBP) and diastolic (DBP) blood pressure is an efficient approach for non-invasive and continuous monitoring of an individual's vitals. Although pulse transit time (PTT) based approaches have been successful in estimating the systolic and diastolic blood pressures to a reasonable degree of accuracy, there is still scope for improvement in terms of accuracies. Moreover, PTT approach requires data from sensors placed at two different locations along with individual calibration of physiological parameters for deriving correct estimation of systolic and diastolic blood pressure (BP) and hence is not suitable for smartphone deployment...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28263079/%C3%AF-expansive-heteroleptic-ruthenium-ii-complexes-as-reverse-saturable-absorbers-and-photosensitizers-for-photodynamic-therapy
#19
Li Wang, Huimin Yin, Mohammed A Jabed, Marc Hetu, Chengzhe Wang, Susan Monro, Xiaolin Zhu, Svetlana Kilina, Sherri A McFarland, Wenfang Sun
Five heteroleptic tris-diimine ruthenium(II) complexes [RuL(N^N)2](PF6)2 (where L is 3,8-di(benzothiazolylfluorenyl)-1,10-phenanthroline and N^N is 2,2'-bipyridine (bpy) (1), 1,10-phenanthroline (phen) (2), 1,4,8,9-tetraazatriphenylene (tatp) (3), dipyrido[3,2-a:2',3'-c]phenazine (dppz) (4), or benzo[i]dipyrido[3,2-a:2',3'-c]phenazine (dppn) (5), respectively) were synthesized. The influence of π-conjugation of the ancillary ligands (N^N) on the photophysical properties of the complexes was investigated by spectroscopic methods and simulated by density functional theory (DFT) and time-dependent DFT...
March 6, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28241577/gouy-phase-shift-for-annular-beam-profiles-in-attosecond-experiments
#20
F Schlaepfer, A Ludwig, M Lucchini, L Kasmi, M Volkov, L Gallmann, U Keller
Attosecond pump-probe measurements are typically performed by combining attosecond pulses with more intense femtosecond, phase-locked infrared (IR) pulses because of the low average photon flux of attosecond light sources based on high-harmonic generation (HHG). Furthermore, the strong absorption of materials at the extreme ultraviolet (XUV) wavelengths of the attosecond pulses typically prevents the use of transmissive optics. As a result, pump and probe beams are typically recombined geometrically with a center-hole mirror that reflects the larger IR beam and transmits the smaller XUV, which leads to an annular beam profile of the IR...
February 20, 2017: Optics Express
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