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Doppler velocimetry

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https://www.readbyqxmd.com/read/28186103/quantum-lock-in-force-sensing-using-optical-clock-doppler-velocimetry
#1
Ravid Shaniv, Roee Ozeri
Force sensors are at the heart of different technologies such as atomic force microscopy or inertial sensing. These sensors often rely on the measurement of the displacement amplitude of mechanical oscillators under applied force. The best sensitivity is typically achieved when the force is alternating at the mechanical resonance frequency of the oscillator, thus increasing its response by the mechanical quality factor. The measurement of low-frequency forces, that are below resonance, is a more difficult task as the resulting oscillation amplitudes are significantly lower...
February 10, 2017: Nature Communications
https://www.readbyqxmd.com/read/28157946/self-mixing-birefringent-dual-frequency-laser-doppler-velocimeter
#2
Junbao Chen, Hongbin Zhu, Wei Xia, Dongmei Guo, Hui Hao, Ming Wang
A self-mixing birefringent dual-frequency laser Doppler velocimeter (SBD-LDV) for high-resolution velocity measurements is presented in this paper. The velocity information of the object can be accurately extracted from the self-mixing Doppler frequency shift of the birefringent light-carried microwave signal. We generate a virtual stable light-carried microwave by using a birefringent dual-frequency He-Ne laser which further simplifies the structure of the light source. Moreover, the optical configuration based on the laser self-mixing interference brings benefits of compact optical setup, self-alignment, and direction discriminability...
January 23, 2017: Optics Express
https://www.readbyqxmd.com/read/28155328/advanced-laser-based-techniques-for-gas-phase-diagnostics-in-combustion-and-aerospace-engineering
#3
Andreas Ehn, Jiajian Zhu, Xuesong Li, Johannes Kiefer
Gaining information of species, temperature, and velocity distributions in turbulent combustion and high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use of optical and spectroscopic techniques, and in particular laser-based diagnostics, has shown outstanding abilities for performing non-intrusive in situ diagnostics. The development of instrumentation, such as robust lasers with high pulse energy, ultra-short pulse duration, and high repetition rate along with digitized cameras exhibiting high sensitivity, large dynamic range, and frame rates on the order of MHz, has opened up for temporally and spatially resolved volumetric measurements of extreme dynamics and complexities...
January 1, 2017: Applied Spectroscopy
https://www.readbyqxmd.com/read/28153658/first-trimester-alcohol-exposure-alters-placental-perfusion-and-fetal-oxygen-availability-affecting-fetal-growth-and-development-in-a-non-human-primate-model
#4
Jamie O Lo, Matthias C Schabel, Victoria H J Roberts, Xiaojie Wang, Katherine S Lewandowski, Kathleen A Grant, Antonio E Frias, Christopher D Kroenke
BACKGROUND: Prenatal alcohol exposure leads to impaired fetal growth, brain development, and stillbirth. Placental impairment likely contributes to these adverse outcomes, but the mechanisms and specific vasoactive effects of alcohol that links altered placental function to impaired fetal development remain areas of active research. OBJECTIVE: Recently, we developed magnetic resonance imaging techniques in nonhuman primates to characterize placental blood oxygenation through measurements of T2* and perfusion using dynamic contrast-enhanced magnetic resonance imaging...
January 30, 2017: American Journal of Obstetrics and Gynecology
https://www.readbyqxmd.com/read/28152557/perinatal-outcome-of-placental-massive-perivillous-fibrin-deposition-a-case-control-study
#5
Louise Devisme, Claire Chauvière, Hélène Franquet-Ansart, Anastasia Chudzinski, Morgane Stichelbout, Véronique Houfflin-Debarge, Damien Subtil
OBJECTIVE: To describe the obstetric outcomes associated with massive perivillous fibrin deposition (MFD) compared with a control series and to determine if outcome differs according to the extent of fibrin deposition. METHOD: Retrospective case-control study based on placentas analyzed over a consecutive 12-years period. MFD was considered severe if it extended over more than 50% of the placenta and moderate between 25 and 50%. RESULTS: During the study period, MFD was observed on 71 placentas, 39 severe and 32 moderate...
February 2, 2017: Prenatal Diagnosis
https://www.readbyqxmd.com/read/28148767/ultrasound-imaging-velocimetry-with-interleaved-images-for-improved-pulsatile-arterial-flow-measurements-a-new-correction-method-experimental-and-in-vivo-validation
#6
Katharine H Fraser, Christian Poelma, Bin Zhou, Eleni Bazigou, Meng-Xing Tang, Peter D Weinberg
Blood velocity measurements are important in physiological science and clinical diagnosis. Doppler ultrasound is the most commonly used method but can only measure one velocity component. Ultrasound imaging velocimetry (UIV) is a promising technique capable of measuring two velocity components; however, there is a limit on the maximum velocity that can be measured with conventional hardware which results from the way images are acquired by sweeping the ultrasound beam across the field of view. Interleaved UIV is an extension of UIV in which two image frames are acquired concurrently, allowing the effective interframe separation time to be reduced and therefore increasing the maximum velocity that can be measured...
February 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28147696/an-improved-asay-window-technique-for-investigating-the-micro-spall-of-an-explosively-driven-tin
#7
Yongtao Chen, Renkai Hong, Haoyu Chen, Tiegang Tang, Guowu Ren
An improved Asay window technique is employed to experimentally investigate the micro-spalling fragments of a melted tin subjected to high explosive loading. Compared to the traditional Asay window, details of the new design are illustrated, through the use of photonic Doppler velocimetry to record high-quality micro-spall signals. The analytical method is established to convert the measured data into the spatial volume density distribution, being in quantitative agreement with that obtained from the x-ray radiograph...
January 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28147596/acoustic-and-streaming-velocity-components-in-a-resonant-waveguide-at-high-acoustic-levels
#8
Virginie Daru, Ida Reyt, Hélène Bailliet, Catherine Weisman, Diana Baltean-Carlès
Rayleigh streaming is a steady flow generated by the interaction between an acoustic wave and a solid wall, generally assumed to be second order in a Mach number expansion. Acoustic streaming is well known in the case of a stationary plane wave at low amplitude: it has a half-wavelength spatial periodicity and the maximum axial streaming velocity is a quadratic function of the acoustic velocity amplitude at antinode. For higher acoustic levels, additional streaming cells have been observed. Results of laser Doppler velocimetry measurements are here compared to direct numerical simulations...
January 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28114884/everrest-prospective-study-a-6-year-prospective-study-to-define-the-clinical-and-biological-characteristics-of-pregnancies-affected-by-severe-early-onset-fetal-growth-restriction
#9
Rebecca Spencer, Gareth Ambler, Jana Brodszki, Anke Diemert, Francesc Figueras, Eduard Gratacós, Stefan R Hansson, Kurt Hecher, Angela Huertas-Ceballos, Neil Marlow, Karel Marsál, Eva Morsing, Donald Peebles, Carlo Rossi, Neil J Sebire, John F Timms, Anna L David
BACKGROUND: Fetal growth restriction (FGR) is a serious obstetric condition for which there is currently no treatment. The EVERREST Prospective Study has been designed to characterise the natural history of pregnancies affected by severe early onset FGR and establish a well phenotyped bio-bank. The findings will provide up-to-date information for clinicians and patients and inform the design and conduct of the EVERREST Clinical Trial: a phase I/IIa trial to assess the safety and efficacy of maternal vascular endothelial growth factor (VEGF) gene therapy in severe early onset FGR...
January 23, 2017: BMC Pregnancy and Childbirth
https://www.readbyqxmd.com/read/28103875/effects-of-plasmodium-falciparum-infection-on-umbilical-artery-resistance-and-intrafetal-blood-flow-distribution-a-doppler-ultrasound-study-from-papua-new-guinea
#10
Maria Ome-Kaius, Stephan Karl, Regina Alice Wangnapi, John Walpe Bolnga, Glen Mola, Jane Walker, Ivo Mueller, Holger Werner Unger, Stephen John Rogerson
BACKGROUND: Doppler velocimetry studies of umbilical artery (UA) and middle cerebral artery (MCA) flow help to determine the presence and severity of fetal growth restriction. Increased UA resistance and reduced MCA pulsatility may indicate increased placental resistance and intrafetal blood flow redistribution. Malaria causes low birth weight and fetal growth restriction, but few studies have assessed its effects on uteroplacental and fetoplacental blood flow. METHODS: Colour-pulsed Doppler ultrasound was used to assess UA and MCA flow in 396 Papua New Guinean singleton fetuses...
January 19, 2017: Malaria Journal
https://www.readbyqxmd.com/read/28103551/ultrasound-flow-mapping-for-the-investigation-of-crystal-growth
#11
Norman Thieme, Paul Bonisch, Dagmar Meier, Richard Nauber, Lars Buttner, Kaspars Dadzis, Olf Patzold, Lamine Sylla, Jurgen Czarske
A high energy conversion and cost efficiency are keys for the transition to renewable energy sources, e.g. solar cells. The efficiency of multi-crystalline solar cells can be improved by enhancing the understanding of its crystallization process, especially the directional solidification. In this paper, a novel measurement system for the characterization of flow phenomena and solidification processes in low-temperature model experiments on the basis of ultrasound Doppler velocimetry is described. It captures turbulent flow phenomena in two planes with a frame rate of 3...
January 16, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28059254/nonmechanical-scanning-laser-doppler-velocimetry-for-distribution-measurements-of-two-dimensional-velocity-vectors-based-on-optical-quadrature-detection
#12
Koichi Maru
This paper proposes a nonmechanical scanning laser Doppler velocimeter (LDV) for measuring the distribution of two-dimensional velocity vectors. In the proposed LDV, an optical quadrature detection technique and a nonmechanical axial scanning technique are introduced into a reference-type LDV. Consequently, the LDV has a simple optical system without multiple light sources or frequency shifting and does not have any moving mechanisms in the probe. The experimental results obtained using a sensor probe setup indicate that the function of measuring two-dimensional velocity vectors and the scanning function are successfully demonstrated...
December 20, 2016: Applied Optics
https://www.readbyqxmd.com/read/28050448/accuracy-of-pelvic-mass-score-in-pre-operative-determination-of-malignancy-in-adnexal-masses
#13
Lakshmi Mohan, Arun Rao, Sonali Ullal, Gowtham Krishna
INTRODUCTION: Suspicious adnexal masses are common clinical problems in gynaecological practice. A reliable diagnostic tool for the early detection of the ovarian malignancy is essential. AIM: To validate a new scoring system -Pelvic Mass Score (PMS) in predicting the nature of the adnexal mass pre-operatively. MATERIALS AND METHODS: A prospective observational study was carried out in 100 consenting women with an undiagnosed adnexal mass requiring operative intervention...
November 2016: Journal of Clinical and Diagnostic Research: JCDR
https://www.readbyqxmd.com/read/28029583/acr-appropriateness-criteria-assessment-of-fetal-well-being
#14
Lynn Simpson, Nadia J Khati, Sandeep P Deshmukh, Kika M Dudiak, Mukesh G Harisinghani, Tara L Henrichsen, Benjamin J Meyer, David A Nyberg, Liina Poder, Thomas D Shipp, Carolyn M Zelop, Phyllis Glanc
Although there is limited evidence that antepartum testing decreases the risk for fetal death in low-risk pregnancies, women with high-risk factors for stillbirth should undergo antenatal fetal surveillance. The strongest evidence supporting antepartum testing pertains to pregnancies complicated by intrauterine fetal growth restriction secondary to uteroplacental insufficiency. The main ultrasound-based modalities to determine fetal health are the biophysical profile, modified biophysical profile, and duplex Doppler velocimetry...
October 28, 2016: Journal of the American College of Radiology: JACR
https://www.readbyqxmd.com/read/27957524/fetal-hemodynamic-parameters-in-low-risk-pregnancies-doppler-velocimetry-of-uterine-umbilical-and-middle-cerebral-artery
#15
C O Figueira, F G Surita, M S Dertkigil, S L Pereira, J R Bennini, S S Morais, J Mayrink, J G Cecatti
Objective. To elaborate curves of longitudinal reference intervals of pulsatility index (PI) and systolic velocity (SV) for uterine (UtA), umbilical (UA), and middle cerebral arteries (MCA), in low risk pregnancies. Methods. Doppler velocimetric measurements of PI and SV from 63 low risk pregnant women between 16 and 41 weeks of gestational age. Means (±SD) for intervals of gestational age and percentiles 5, 50, and 95 were calculated for each parameter. The Intraclass Correlation Coefficients (ICC) were also estimated for assessing intra- and intervariability of measurements...
2016: TheScientificWorldJournal
https://www.readbyqxmd.com/read/27956506/hugoniot-equation-of-state-of-rock-materials-under-shock-compression
#16
Q B Zhang, C H Braithwaite, J Zhao
Two sets of shock compression tests (i.e. conventional and reverse impact) were conducted to determine the shock response of two rock materials using a plate impact facility. Embedded manganin stress gauges were used for the measurements of longitudinal stress and shock velocity. Photon Doppler velocimetry was used to capture the free surface velocity of the target. Experimental data were obtained on a fine-grained marble and a coarse-grained gabbro over a shock pressure range of approximately 1.5-12 GPa...
January 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/27941711/recurrent-acute-myocardial-infarction-in-a-patient-with-severe-coronary-artery-ectasia-implication-of-antithrombotic-therapy
#17
Tomoko Tomioka, Satoshi Takeuchi, Yoshitaka Ito, Hiroki Shioiri, Jiro Koyama, Kanichi Inoue
BACKGROUND Acute myocardial infarction (AMI) can be caused not only by plaque rupture/erosion, but also by many other mechanisms. Thromboembolism due to atrial fibrillation and coronary thrombosis due to coronary artery ectasia are among the causes. Here we report on a case of recurrent myocardial infarction with coronary artery ectasia. CASE REPORT Our case was a 78-year-old woman with hypertension. Within a one-month interval, she developed AMI twice at the distal portion of her right coronary artery along with coronary artery ectasia...
December 12, 2016: American Journal of Case Reports
https://www.readbyqxmd.com/read/27939906/hypoperfusion-in-response-to-epinephrine-in-local-anaesthetics-investigation-of-dependence-on-epinephrine-concentration-spread-of-hypoperfusion-and-time-to-maximal-cutaneous-vasoconstriction
#18
Rafi Sheikh, Khashayar Memarzadeh, Christian Torbrand, Jonas Blohmé, Malin Malmsjö
OBJECTIVES: The present study aimed to examine hypoperfusion in response to epinephrine following the administration of a local anaesthetic. The concentration of epinephrine that causes maximal hypoperfusion, the spread of hypoperfusion in the tissue and the time to the stabilization of hypoperfusion were investigated. METHODS: Blood perfusion was monitored using laser Doppler velocimetry and laser speckle contrast imaging of random-pattern advancement flaps (1 × 4 cm) or intact skin on the pig flank...
November 11, 2016: Journal of Plastic, Reconstructive & Aesthetic Surgery: JPRAS
https://www.readbyqxmd.com/read/27939473/bedside-cardiovascular-maternal-interrogation-in-the-first-trimester-to-predict-different-phenotypes-of-hypertensive-disorders-in-pregnancy
#19
Daniela Denis Di Martino, Tamara Stampalija, Eleonora Rosti, Daniela Casati, Valentina Signorelli, Sara Zullino, Cristina Mastroianni, Mariachiara Quadrifoglio, Enrico Ferrazzi
OBJECTIVE: The aim is to evaluate if maternal cardiovascular indices, in the first trimester of pregnancy, might be useful to differentiate women who develop different hypertensive disorders of pregnancy (HDP). STUDY DESIGN: Method: 1399 pregnant women attending screening for chromosomal aneuploidies were recruited. The following parameters were measured: Doppler Velocimetry of uterine arteries; Peripheral blood pressure; Aortic Pressure derived from applanation tonometry...
October 2016: Pregnancy Hypertension
https://www.readbyqxmd.com/read/27934516/impact-of-spatial-distribution-of-charged-groups-in-core-poly-n-isopropylacrylamide-based-microgels-on-the-resultant-composite-structures-prepared-by-seeded-emulsion-polymerization-of-styrene
#20
Takumi Watanabe, Chiaki Kobayashi, Chihong Song, Kazuyoshi Murata, Takuma Kureha, Daisuke Suzuki
A series of raspberry-shaped composite microgels were synthesized by seeded emulsion polymerization of styrene in the presence of hydrogel particles with different distributions of charged groups. Unlike microgels whose charged groups are localized in their center,29 polystyrene nanoparticles were formed inside the core microgels when the microgels whose charged groups were localized on their surface were used as cores for seeded emulsion polymerization. The effects of the surface charge densities of the core microgels and the concentration of styrene monomer during the polymerization on the resultant structures of composite microgels were investigated...
December 6, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
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