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Pulse transit time

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https://www.readbyqxmd.com/read/28207773/local-versus-global-aortic-pulse-wave-velocity-in-early-atherosclerosis-an-animal-study-in-apoe-mice-using-ultrahigh-field-mri
#1
Alexander Gotschy, Wolfgang R Bauer, Patrick Winter, Peter Nordbeck, Eberhard Rommel, Peter M Jakob, Volker Herold
Increased aortic stiffness is known to be associated with atherosclerosis and has a predictive value for cardiovascular events. This study aims to investigate the local distribution of early arterial stiffening due to initial atherosclerotic lesions. Therefore, global and local pulse wave velocity (PWV) were measured in ApoE-/- and wild type (WT) mice using ultrahigh field MRI. For quantification of global aortic stiffness, a new multi-point transit-time (TT) method was implemented and validated to determine the global PWV in the murine aorta...
2017: PloS One
https://www.readbyqxmd.com/read/28198883/angle-resolved-coherent-wave-mixing-using-a-4%C3%A2-%C3%A2-fs-ultra-broad-bandwidth-laser
#2
I P Mercer, T Witting, T Driver, R J Cogdell, J P Marangos, J W G Tisch
We demonstrate angle-resolved coherent (ARC) wave mixing using 4 fs light pulses derived from a laser source that spans 550-1000 nm. We believe this to be the shortest pulse duration used to date in coherent multi-dimensional spectroscopy. The marriage of this ultra-broad band, few-cycle coherent source with the ARC technique will permit new investigations of the interplay between energy transfers and quantum superposition states spanning 8200  cm<sup>-1</sup>. We applied this configuration to measurements on the photosynthetic low light (LL) complex from Rhodopseudomonas palustris in solution at ambient temperature...
February 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28179195/multiplexed-mri-methods-for-rapid-estimation-of-global-cerebral-metabolic-rate-of-oxygen-consumption
#3
Hyunyeol Lee, Michael C Langham, Ana E Rodriguez-Soto, Felix W Wehrli
The global cerebral metabolic rate of oxygen (CMRO2), which reflects metabolic activity of the brain under various physiologic conditions, can be quantified using a method, referred to as 'OxFlow', which simultaneously measures hemoglobin oxygen saturation in a draining vein (Yv) and total cerebral blood flow (tCBF). Conventional OxFlow (Conv-OxFlow) entails four interleaves incorporated in a single pulse sequence - two for phase-contrast based measurement of tCBF in the supplying arteries of the neck, and two to measure the intra- to extravascular phase difference in the superior sagittal sinus to derive Yv [Jain et al...
February 6, 2017: NeuroImage
https://www.readbyqxmd.com/read/28166774/highly-wearable-cuff-less-blood-pressure-and-heart-rate-monitoring-with-single-arm-electrocardiogram-and-photoplethysmogram-signals
#4
Qingxue Zhang, Dian Zhou, Xuan Zeng
BACKGROUND: Long-term continuous systolic blood pressure (SBP) and heart rate (HR) monitors are of tremendous value to medical (cardiovascular, circulatory and cerebrovascular management), wellness (emotional and stress tracking) and fitness (performance monitoring) applications, but face several major impediments, such as poor wearability, lack of widely accepted robust SBP models and insufficient proofing of the generalization ability of calibrated models. METHODS: This paper proposes a wearable cuff-less electrocardiography (ECG) and photoplethysmogram (PPG)-based SBP and HR monitoring system and many efforts are made focusing on above challenges...
February 6, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28161327/unveiling-the-excited-state-energy-transfer-pathways-in-peridinin-chlorophyll-a-protein-by-ultrafast-multi-pulse-transient-absorption-spectroscopy
#5
Kipras Redeckas, Vladislava Voiciuk, Donatas Zigmantas, Roger G Hiller, Mikas Vengris
Time-resolved multi-pulse methods were applied to investigate the excited state dynamics, the interstate couplings, and the excited state energy transfer pathways between the light-harvesting pigments in peridinin-chlorophyll a-protein (PCP). The utilized pump-dump-probe techniques are based on perturbation of the regular PCP energy transfer pathway. The PCP complexes were initially excited with an ultrashort pulse, resonant to the S0→S2 transition of the carotenoid peridinin. A portion of the peridinin-based emissive intramolecular charge transfer (ICT) state was then depopulated by applying an ultrashort NIR pulse that perturbed the interaction between S1 and ICT states and the energy flow from the carotenoids to the chlorophylls...
February 2, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28159487/the-use-of-pulse-transit-time-in-pediatric-sleep-studies-a-systematic-review
#6
REVIEW
Laurelle A Smith, Patrick J Dawes, Barbara C Galland
As a surrogate measure of blood pressure, pulse transit time (PTT) is commonly used in studies investigating arterial function and respiratory sleep disturbance. A systematic search of the literature was conducted with the aim of reviewing the usefulness of the technique within pediatric sleep studies. All studies that used PTT as a diagnostic tool during sleep in infants, children or adolescents were considered. The search yielded 425 articles, of which 21 full-text articles met inclusion criteria, the majority reporting on obstructive sleep apnea (OSA)...
November 30, 2016: Sleep Medicine Reviews
https://www.readbyqxmd.com/read/28158243/long-term-pulse-wave-velocity-outcomes-with-aerobic-and-resistance-training-in-kidney-transplant-recipients-a-pilot-randomised-controlled-trial
#7
Ellen M O'Connor, Pelagia Koufaki, Thomas H Mercer, Herolin Lindup, Eilish Nugent, David Goldsmith, Iain C Macdougall, Sharlene A Greenwood
BACKGROUND: This pilot study examined long-term pulse wave velocity (PWV) and peak oxygen uptake (VO2peak) outcomes following a 12-week moderate-intensity aerobic or resistance training programme in kidney transplant recipients. METHOD: Single-blind, bi-centre randomised controlled parallel trial. 42 out of 60 participants completed a 9-month follow-up assessment (Aerobic training = 12, Resistance training = 10 and usual care = 20). Participants completed 12 weeks of twice-weekly supervised aerobic or resistance training...
2017: PloS One
https://www.readbyqxmd.com/read/28126420/respiratory-effort-from-the-photoplethysmogram
#8
Paul S Addison
The potential for a simple, non-invasive measure of respiratory effort based on the pulse oximeter signal - the photoplethysmogram or 'pleth' - was investigated in a pilot study. Several parameters were developed based on a variety of manifestations of respiratory effort in the signal, including modulation changes in amplitude, baseline, frequency and pulse transit times, as well as distinct baseline signal shifts. Thirteen candidate parameters were investigated using data from healthy volunteers. Each volunteer underwent a series of controlled respiratory effort maneuvers at various set flow resistances and respiratory rates...
January 23, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28113300/estimation-of-pulse-transit-time-as-a-function-of-blood-pressure-using-a-nonlinear-arterial-tube-load-model
#9
Mingwu Gao, Hao-Min Cheng, Shih-Hsien Sung, Chen-Huan Chen, Nicholas B Olivier, Ramakrishna Mukkamala
OBJECTIVE: Pulse transit time (PTT) varies with blood pressure (BP) throughout the cardiac cycle, yet, because of wave reflection, only one PTT value at the diastolic BP level is conventionally estimated from proximal and distal BP waveforms. The objective was to establish a technique to estimate multiple PTT values at different BP levels in the cardiac cycle. METHODS: A technique was developed for estimating PTT as a function of BP (to indicate the PTT value for every BP level) from proximal and distal BP waveforms...
September 22, 2016: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28113242/a-novel-method-for-continuous-non-invasive-cuff-less-measurement-of-blood-pressure-evaluation-in-patients-with-non-alcoholic-fatty-liver-disease
#10
Trine Seeberg, James Orr, Hanne Austad, Morten Roed, Steffen Dalgard, David Houghton, David Jones, Frode Strisland
OBJECTIVE: One promising approach for a continuous, non-invasive, cuff-less ambulatory BP monitor is to measure the pulse wave velocity or the inversely proportional pulse transit time (PTT), based on electrical and optical physiological measurements in the chest area. A device termed IsenseU-BP+ has been developed for measuring continuous BP, as well as other physiological data. The objective of this paper is to present results from the first clinical evaluation with a wide range of patients...
September 12, 2016: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28102355/determining-arterial-wave-transit-time-from-a-single-aortic-pressure-pulse-in-rats-vascular-impulse-response-analysis
#11
Ru-Wen Chang, Chun-Yi Chang, Liang-Chuan Lai, Ming-Shiou Wu, Tai-Horng Young, Yih-Sharng Chen, Chih-Hsien Wang, Kuo-Chu Chang
Arterial wave transit time (τw) in the lower body circulation is an effective biomarker of cardiovascular risk that substantially affects systolic workload imposed on the heart. This study evaluated a method for determining τw from the vascular impulse response on the basis of the measured aortic pressure and an assumed triangular flow (Q(tri)). The base of the unknown Q(tri) was constructed with a duration set equal to ejection time. The timing of the peak triangle was derived using a fourth-order derivative of the pressure waveform...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28090301/pulmonary-pulse-wave-transit-time-is-associated-with-right-ventricular-pulmonary-artery-coupling-in-pulmonary-arterial-hypertension
#12
Kurt W Prins, E Kenneth Weir, Stephen L Archer, Jeremy Markowitz, Lauren Rose, Marc Pritzker, Richard Madlon-Kay, Thenappan Thenappan
Pulmonary pulse wave transit time (pPTT), defined as the time for the systolic pressure pulse wave to travel from the pulmonary valve to the pulmonary veins, has been reported to be reduced in pulmonary arterial hypertension (PAH); however, the underlying mechanism of reduced pPTT is unknown. Here, we investigate the hypothesis that abbreviated pPTT in PAH results from impaired right ventricular-pulmonary artery (RV-PA) coupling. We quantified pPTT using pulsed-wave Doppler ultrasound from 10 healthy age- and sex-matched controls and 36 patients with PAH...
December 2016: Pulmonary Circulation
https://www.readbyqxmd.com/read/28089491/satellite-and-central-transitions-selective-1-h-27-al-d-hmqc-experiments-at-very-fast-mas-for-quadrupolar-couplings-determination
#13
Nghia Tuan Duong, Yusuke Nishiyama
Recent study has demonstrated the application of the proton-detected heteronuclear multi-quantum coherence (HMQC) at ultrafast Magic Angle Spinning (MAS) to probe quadrupolar nuclei including (14)N and (35)Cl. In addition, for half-integer quadrupolar nucleus like (35)Cl, the quadrupolar product can be calculated based on the shift difference between the center band of satellite transition (ST) and the central transition (CT) peaks. The applicability of this technique is further investigated on spin I=5/2, namely (27)Al nucleus, and kaolin is chosen as the testing sample...
January 4, 2017: Solid State Nuclear Magnetic Resonance
https://www.readbyqxmd.com/read/28071764/aligned-copper-nanorod-arrays-for-highly-efficient-generation-of-intense-ultra-broadband-thz-pulses
#14
S Mondal, Q Wei, W J Ding, H A Hafez, M A Fareed, A Laramée, X Ropagnol, G Zhang, S Sun, Z M Sheng, J Zhang, T Ozaki
We demonstrate an intense broadband terahertz (THz) source based on the interaction of relativistic-intensity femtosecond lasers with aligned copper nanorod array targets. For copper nanorod targets with a length of 5 μm, a maximum 13.8 times enhancement in the THz pulse energy (in ≤20 THz spectral range) is measured as compared to that with a thick plane copper target under the same laser conditions. A further increase in the nanorod length leads to a decrease in the THz pulse energy at medium frequencies (≤20 THz) and increase of the electromagnetic pulse energy in the high-frequency range (from 20-200 THz)...
January 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28065997/rapid-evaporation-at-the-superheat-limit-of-methanol-ethanol-butanol-and-n-heptane-on-platinum-films-supported-by-low-stress-sin-membranes
#15
Eric J Ching, C Thomas Avedisian, Richard C Cavicchi, Do Hyun Chung, Jeff Rah, Michael J Carrier
The bubble nucleation temperatures of several organic liquids (methanol, ethanol, butanol, n-heptane) on stress-minimized platinum (Pt) films supported by SiN membranes is examined by pulse-heating the membranes for times ranging from 1 µs to 10 µs. The results show that the nucleation temperatures increase as the heating rates of the Pt films increase. Measured nucleation temperatures approach predicted superheat limits for the smallest pulse times which correspond to heating rates over 10(8) K/s, while nucleation temperatures are significantly lower for the longest pulse times...
October 2016: International Journal of Heat and Mass Transfer
https://www.readbyqxmd.com/read/28063656/effect-of-cyclic-redox-oscillations-on-water-quality-in-freshwater-acid-sulfate-soil-wetlands
#16
Niloofar Karimian, Scott G Johnston, Edward D Burton
Restoration of acid sulfate soil (ASS) wetlands by freshwater re-flooding can lead to the reformation of various Fe(II) and reduced inorganic sulfur (RIS) species in surface soil layers. However, in many locations, wetland water levels undergo large seasonal fluctuations that drive extreme redox oscillations. Newly formed RIS species [e.g. greigite, mackinawite, nano-pyrite and S(0)] and Fe(II) are vulnerable to rapid oxidation during dry periods and may generate substantial acidity. Rainfall following a dry period may then mobilise acidity and metal cations in surface waters prior to eventual recovery in pH by re-establishment of reducing conditions...
January 4, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28060961/pilot-study-estimation-of-stroke-volume-and-cardiac-output-from-pulse-wave-velocity
#17
Yurie Obata, Maki Mizogami, Daniel Nyhan, Dan E Berkowitz, Jochen Steppan, Viachaslau Barodka
BACKGROUND: Transesophageal echocardiography (TEE) is increasingly replacing thermodilution pulmonary artery catheters to assess hemodynamics in patients at high risk for cardiovascular morbidity. However, one of the drawbacks of TEE compared to pulmonary artery catheters is the inability to measure real time stroke volume (SV) and cardiac output (CO) continuously. The aim of the present proof of concept study was to validate a novel method of SV estimation, based on pulse wave velocity (PWV) in patients undergoing cardiac surgery...
2017: PloS One
https://www.readbyqxmd.com/read/28059179/rabi-oscillations-produced-by-adiabatic-pulse-due-to-initial-atomic-coherence
#18
Anatoly A Svidzinsky, Hichem Eleuch, Marlan O Scully
If an electromagnetic pulse is detuned from atomic transition frequency by amount Δ>1/τ, where τ is the turn-on time of the pulse, then atomic population adiabatically follows the pulse intensity without causing Rabi oscillations. Here we show that, if initially, the atom has nonzero coherence, then the adiabatic pulse yields Rabi oscillations of atomic population ρ<sub>aa</sub>(t), and we obtain analytical solutions for ρ<sub>aa</sub>(t). Our findings can be useful for achieving generation of coherent light in the backward direction in the QASER scheme in which modulation of the coupling between light and atoms is produced by Rabi oscillations...
January 1, 2017: Optics Letters
https://www.readbyqxmd.com/read/28046980/we-fg-206-05-new-arterial-spin-labeling-method-for-simultaneous-estimation-of-arterial-cerebral-blood-volume-cerebral-blood-flow-and-arterial-transit-time
#19
M Johnston, H Liu, C Whitlow, Y Jung
PURPOSE: To demonstrate the feasibility of a novel Arterial Spin Labeling (ASL) method for simultaneously measuring cerebral blood flow (CBF), arterial transit time (ATT), and arterial cerebral blood volume (aCBV) without the use of a contrast agent. METHODS: A series of multi-TI ASL images were acquired from one healthy subject on a 3T Siemens Skyra, with the following parameters: PCASL labeling with variable TI [300, 400, 500, 600, 700, 800, 900, 1000, 1500, 2000, 2500, 3000, 3500, 4000] ms, labeling bolus 1400 ms when TI allows, otherwise 100 ms less than TI, TR was minimized for each TI, two sinc shaped pre-saturation pulses were applied in the imaging plane immediately before 2D EPI acquisition...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28018731/accurate-measurement-of-the-pulse-wave-delay-with-imaging-photoplethysmography
#20
Alexei A Kamshilin, Igor S Sidorov, Laura Babayan, Maxim A Volynsky, Rashid Giniatullin, Oleg V Mamontov
Assessment of the cardiovascular parameters using noncontact video-based or imaging photoplethysmography (IPPG) is usually considered as inaccurate because of strong influence of motion artefacts. To optimize this technique we performed a simultaneous recording of electrocardiogram and video frames of the face for 36 healthy volunteers. We found that signal disturbances originate mainly from the stochastically enhanced dichroic notch caused by endogenous cardiovascular mechanisms, with smaller contribution of the motion artefacts...
December 1, 2016: Biomedical Optics Express
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