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This paper introduces a novel method for the three-dimensional characterization of flyers based on microscopic photonic Doppler velocimetry (PDV) velocity field measurements. By strategically positioning 56 PDV velocity measurement spots within a circle of 0.50 mm diameter at an interval of approximately 58 μm, we achieve spatially resolved measurements of the velocity history of the flyer during its flight within the barrel and subsequent impact on a transparent window. Crucial data, such as displacement history, impact time, and impact pulse duration, can be extracted at each measurement spot. Furthermore, a correlation analysis of these datasets enables the reconstruction of the flyer's three-dimensional morphology, both during its flight inside the barrel and at the critical moment of impact with the window. This method offers a remarkable temporal resolution in the order of nanoseconds and a spatial resolution in the order of micrometers. With the characteristics of high spatial resolution and high experimental efficiency, the microscope PDV technology is poised to become an essential research tool in the study of action mechanisms, design optimization, and determination of initiation criteria for exploding foil initiators. [ABSTRACT FROM AUTHOR]

Properties of fragmentation from an explosively driven 316L stainless steel spherical shell section fabricated by a laser powder bed additive manufacturing process with minimal surface finishing are investigated. This shell is driven by an insensitive high explosive, resulting in high strain rate deformation (>8 × 103 s−1) and failure of the stainless steel. Photonic Doppler velocimetry measures the expansion rate; dynamic radiography and high-speed imaging capture the fracture behavior of the stainless steel. The fracture response of the additively manufactured stainless steel shell is compared to published experimental results on additively manufactured 316L stainless steel and conventionally manufactured wrought 316L and 304 stainless steel shell fragmentation. Despite preferred crack orientation, suggesting the influence of surface grooves on fracture time, fragment size is identical to that measured in a similar experiment on wrought 304 stainless steel. Further analysis indicates that the 316L additively manufactured stainless steel shell exhibits comparable spall strength and fragmentation toughness to conventionally manufactured stainless steel yet lower failure strain due to surface stress concentrations. [ABSTRACT FROM AUTHOR]

To accelerate the convergence rate of high-dimensional optimization problems, inspired by the cooperative hunting process of spider colonies named Anelosimus eximius, a new A. eximius colony algorithm (AECA) was proposed to solve combinatorial optimization problems. In the AECA, a certain direction component of the problem solution is represented as a certain direction in which a spider travels, so that a high-dimensional optimization problem can be transformed into multiple low-dimensional optimization problems. The AECA includes two intelligent behaviors: the random walk of spiders and the summoning of the initiator. The random walk of spiders ensures the diversity of spider colonies, whereas the summoning of the initiator can accelerate the convergence rate. We theoretically proved that the AECA is globally convergent. The inversion method of asteroid spectrum reflectance template can be used to solve the problem that the measured planetary spectrum is affected by the asteroid absorption effect and improves the accuracy of celestial Doppler difference velocimetry, which uses celestial spectrum to provide the information of velocity measurement for navigation. The essence of this method is the optimal combination problem of intrinsic mode functions (IMFs). We applied the AECA to the inversion of the planetary spectrum reflectance template. Experimental results show that, compared with genetic algorithms (GAs), the AECA can obtain the optimal combination of spectrum reflectance templates faster. In addition, to verify the universality of the AECA, for the classical knapsack problem, the AECA has a better optimization effect, faster convergence rate, and higher stability than other swarm intelligence algorithms such as GA, discrete particle swarm optimization, and the quantum genetic algorithm. [ABSTRACT FROM AUTHOR]

An understanding of turbulence and mixing is essential to the knowledge of turbulent dissipation, sediment transport, advection of nutrient-rich and organic effluents, and stormwater runoff in prototype water systems, as well as in laboratory channels used for physical modeling of geometrically-scaled full-scale water bodies and for validation of computational models. The acoustic Doppler velocimeter (ADV) system is a robust instrument well suited for such turbulence measurements in open channel flows. The application of acoustic Doppler velocimeter to transient free-surface flows is reviewed in this paper. Based upon field applications and laboratory experiments, the intricacy and inherent difficulties are discussed. The experience and expertise in transient flows highlighted the importance of the signal processing and precise synchronization. Finally, we stress a major benefit of the acoustic Doppler velocimetry for its capability to be used in both field and laboratory, in turn providing some level of confidence in the comparison between full-scale and laboratory data. [ABSTRACT FROM AUTHOR]

Ultrasound velocimetry has been widely used for blood flow imaging. However, the flow measurements are constrained to resolve the in‐plane 2D flow components when using a 1D transducer array. In this work, an ultrasound speckle decorrelation analysis‐based velocimetry (3C‐vUS) is proposed for 3D velocity components measurement using a 1D transducer array. The 3C‐vUS theory is first derived and validated with numerical simulations and phantom experiments. The in vivo testing results show that 3C‐vUS can accurately measure the blood flow 3D‐velocity‐components of the human carotid artery at arbitrary probe‐to‐vessel angles throughout the cardiac cycle. With such capability, the 3C‐vUS will alleviate the requirement of operators and promote disease screening for blood flow‐related disorders. [ABSTRACT FROM AUTHOR]

Background/Objectives: The utility of shear wave elastography (SWE) as an adjunct to ultrasound biometry and Doppler velocimetry for the examination of placental dysfunction and suboptimal fetal growth is unclear. To date, limited data exist correlating the mechanical properties of placentae with fetal growth. This study aimed to investigate the relationship between placental shear wave velocity (SWV) and ultrasound estimated fetal weight (EFW), and to ascertain if placental SWV is a suitable proxy measure of placental function in the surveillance of small-for-gestational-age (SGA) pregnancies. Methods: This prospective, observational cohort study compared the difference in placental SWV between SGA and appropriate-for-gestational-age (AGA) pregnancies. There were 221 women with singleton pregnancies in the study cohort—136 (61.5%) AGA and 85 (38.5%) SGA. Fetal biometry, Doppler velocimetry, the deepest vertical pocket of amniotic fluid, and mean SWV were measured at 2–4-weekly intervals from recruitment to birth. Results: There was no difference in mean placental SWV in SGA pregnancies compared to AGA pregnancies, nor was there any relationship to EFW. Conclusions: Although other studies have shown some correlation between increased placental stiffness and SGA pregnancies, our investigation did not support this. The mechanical properties of placental tissue in SGA pregnancies do not result in placental SWVs that are apparently different from those of AGA controls. As this study did not differentiate between constitutionally or pathologically small fetuses, further studies in growth-restricted cohorts would be of benefit. [ABSTRACT FROM AUTHOR]

Objective: Fetoscopic closure of spina bifida using heated and humidified carbon dioxide gas (hhCO2) has been associated with lower maternal morbidity compared with open closure. Fetal cardiovascular changes during these surgical interventions are poorly defined. Our objective was to compare fetal bradycardia (defined as fetal heart rate (FHR) < 110 bpm for 10 min) and changes in umbilical artery (UA) Doppler parameters during open vs fetoscopic closure. Methods: This was a prospective cohort study of 22 open and 46 fetoscopic consecutive in‐utero closures conducted between 2019 and 2023. Both cohorts had similar preoperative counseling and clinical management. FHR and UA Doppler velocimetry were obtained systematically during preoperative assessment, every 5 min during the intraoperative period, and during the postoperative assessment. FHR, UA pulsatility index (PI) and UA end‐diastolic flow (EDF) were segmented into hourly periods during surgery, and the lowest values were averaged for analysis. Umbilical vein maximum velocity was measured in the fetoscopic cohort. At each timepoint at which FHR was recorded, maternal heart rate and systolic and diastolic blood pressure were measured. Results: Fetal bradycardia occurred in 4/22 (18.2%) cases of open closure and 21/46 (45.7%) cases of fetoscopic closure (P = 0.03). FHR decreased gradually in both cohorts after administration of general anesthesia and decreased further during surgery. FHR was significantly lower during hour 2 of surgery in the fetoscopic‐repair cohort compared with the open‐repair cohort. The change in FHR from baseline in the final stage of fetal surgery was significantly more pronounced in the fetoscopic‐repair cohort compared with the open‐repair cohort (mean, −32.4 (95% CI, −35.7 to −29.1) bpm vs −23.5 (95% CI, −28.1 to −18.8) bpm; P = 0.002). Abnormal UA‐EDF (defined as absent or reversed EDF) occurred in 3/22 (13.6%) cases in the open‐repair cohort and 23/46 (50.0%) cases in the fetoscopic‐repair cohort (P = 0.004). There were no differences in UA‐EDF or UA‐PI between closure techniques at the individual stages of assessment. Conclusions: We observed a decrease in FHR and abnormalities in UA Doppler parameters during both open and fetoscopic spina bifida closure. Fetal bradycardia was more prominent during fetoscopic closure following hhCO2 insufflation, but FHR recovered after cessation of hhCO2. Changes in FHR and UA Doppler parameters during in‐utero spina bifida closure were transient, no cases required emergency delivery and no fetoscopic closure was converted to open closure. These observations should inform algorithms for the perioperative management of fetal bradycardia associated with in‐utero spina bifida closure. © 2024 International Society of Ultrasound in Obstetrics and Gynecology. Linked article: There is a comment on this article by Rychik. Click here to view the Editorial. [ABSTRACT FROM AUTHOR]

The phenomenon of mass ejection from shocked surface is a crucial issue in high-energy density physics and shock compression science. Ejecta from double-shock loaded metallic targets is important in some practical applications, but there are only a few research types on this aspect due to experimental difficulty. We proposed a new method of double-shock loading based on intense laser, that is, the laser is injected into a vacuum hohlraum to generate strong radiation and plasma jet simultaneously, and the target are respectively subjected to two shocks by these two different mechanisms. In the experiment, double-shock process was clearly observed by photonic Doppler velocimetry system, and the recompression of target due to the second shock was presented by x-ray photography. After the free surface was broken, the ejecta showed a unique multi-layer density structure for the first time. This work achieves effective double-shock loading with only one single laser pulse, which is valuable for understanding the metal damage under multiple shocks and the evolution of ejected materials. It also provides an experimental design for studying the material response in complex environments. [ABSTRACT FROM AUTHOR]

Vegetation plays a key role in trapping sediments and further controlling pollutants. However, few studies were conducted to clarify the erosion and deposition laws of sediments and the influence factors caused by vegetation patch properties, which is not conducive to the revelation of riverbank protection and erosion prevention. Therefore, this study investigated the change in scouring and deposition characteristics around submerged vegetation patches of nine kinds of typical configurations and their influencing factors. Vegetation patches were assembled from three vegetation densities (G/d = 0.83, 1.3, and 1.77, representing dense, medium, and sparse, respectively), and three vegetation patch thicknesses (dn = 170, 400, and 630, representing narrow, usual, and wide, respectively), to measure vegetation patch property influences. Flow velocity, scouring, and deposition characteristics under nine patches were determined by a hydraulic flume experiment, three-dimensional acoustic Doppler velocimetry (ADV), and three-dimensional laser scanner, and then ten geometry and morphology indices were measured and calculated based on the results of laser scanning. Results showed that both vegetation patch density and thickness were positively related to the turbulence kinetic energy (TKE) above the vegetation canopy, and only vegetation patch density was negatively related to the flow velocity above the vegetation canopy. The relation between the product of density and vegetation patch thickness and erosion area in planform (EA) showed a power function (R2 = 0.644). Both density and vegetation patch thickness determined the scouring degree, but deposition location and amount did not rely on each one simply. On average, medium density showed the smallest maximum erosion length (MEL), EA, deposition area in planform (DA), and average deposition length (ADL) and a minimum of the above parameters also occurred at narrow vegetation patch thickness. The shape factor of the erosion volume (SFEV), the shape factor of the deposition volume (SFDV), ADL, and MEL of medium density and narrow thickness vegetation patch (G/d = 1.3, dn = 170) were significantly smaller than that of other types of patches. DA and equivalent prismatic erosion depth on the erosion area (EPED) were significantly linearly related (R2 = 0.766). Consequently, most sediment was deposited close to the vegetation patch edge. It is suggested that vegetation patch thickness and density should be given to control sediment transport. In particular, natural vegetation growth changes vegetation patch density and then alters vegetation patch thickness. Management and repair need to be first considered. The results of this study shed light on riparian zone recovery and vegetation filter strip mechanism. [ABSTRACT FROM AUTHOR]

Objective: To assess the association of the umbilicocerebral ratio (UCR) with adverse perinatal outcome in late preterm small‐for‐gestational age (SGA) fetuses and to investigate the effect on perinatal outcomes of immediate delivery. Design: Multicentre cohort study with nested randomised controlled trial (RCT). Setting: Nineteen secondary and tertiary care centres. Population: Singleton SGA pregnancies (estimated fetal weight [EFW] or fetal abdominal circumference [FAC] <10th centile) from 32 to 36+6 weeks. Methods: Women were classified: (1) RCT‐eligible: abnormal UCR twice consecutive and EFW below the 3rd centile at/or below 35 weeks or below the 10th centile at 36 weeks; (2) abnormal UCR once or intermittent; (3) never abnormal UCR. Consenting RCT‐eligible patients were randomised for immediate delivery from 34 weeks or expectant management until 37 weeks. Main outcome measures: A composite adverse perinatal outcome (CAPO), defined as perinatal death, birth asphyxia or major neonatal morbidity. Results: The cohort consisted of 690 women. The study was halted prematurely for low RCT‐inclusion rates (n = 40). In the RCT‐eligible group, gestational age at delivery, birthweight and birthweight multiple of the median (MoM) (0.66, 95% confidence interval [CI] 0.59–0.72) were significantly lower and the CAPO (n = 50, 44%, p < 0.05) was more frequent. Among patients randomised for immediate delivery there was a near‐significant lower birthweight (p = 0.05) and higher CAPO (p = 0.07). EFW MoM, pre‐eclampsia, gestational hypertension and Doppler classification were independently associated with the CAPO (area under the curve 0.71, 95% CI 0.67–0.76). Conclusions: Perinatal risk was effectively identified by low EFW MoM and UCR. Early delivery of SGA fetuses with an abnormal UCR at 34–36 weeks should only be performed in the context of clinical trials. [ABSTRACT FROM AUTHOR]

The production of nanomaterials through environmentally friendly methods is a top priority in the sustainable development of nanotechnology. This paper presents data on the synthesis of silver nanoparticles using an aqueous extract of Sphagnum fallax moss at room temperature. The morphology, stability, and size of the nanoparticles were analyzed using various techniques, including transmission electron microscopy, Doppler laser velocimetry, and UV-vis spectroscopy. In addition, Fourier transform infrared spectroscopy was used to analyze the presence of moss metabolites on the surface of nanomaterials. The effects of different concentrations of citrate-stabilized and moss extract-stabilized silver nanoparticles on cell viability, necrosis induction, and cell impedance were compared. The internalization of silver nanoparticles into both monolayers and three-dimensional cells spheroids was evaluated using dark-field microscopy and hyperspectral imaging. An eco-friendly method for the synthesis of silver nanoparticles at room temperature is proposed, which makes it possible to obtain spherical nanoparticles of 20–30 nm in size with high bioavailability and that have potential applications in various areas of human life. [ABSTRACT FROM AUTHOR]

A novel multi-longitudinal mode 532 nm photonic Doppler velocimetry (PDV) was proposed to solve the problem of high bandwidth requirements in shock experiments with velocities up to km/s. Compared to the conventional PDV system operating at 1550 nm, the utilization of a shorter wavelength of 532 nm enables nearly three times the velocity resolution. However, it also leads to a threefold increase in the Doppler frequency shift for a given velocity. To mitigate the bandwidth constraints, a multi-longitudinal mode laser is employed to downconvert the signal, effectively reducing the bandwidth requirements. The efficacy of this method is validated through theoretical analysis and experimental investigations on detonation shock scenarios. Furthermore, this approach eliminates the necessity for modulators, frequency shifters, and other devices, facilitating its applicability to non-communication bands. [ABSTRACT FROM AUTHOR]

The apparent velocity measured by an interferometric surface velocimeter is a function of both the surface velocity and the time derivative of the refractive index along the measurement path. We employed this dual sensitivity to simultaneously measure km/s surface velocities and 1018 cm−3 average plasma densities with combined VISAR (velocity interferometer system for any reflector) and PDV (photonic Doppler velocimetry) measurements in experiments performed on the Z Pulsed Power Facility. We detail the governing equations, associated assumptions, and analysis specifics and show that the surface velocity can be extracted without knowledge of the specific plasma density profile. [ABSTRACT FROM AUTHOR]

The Disc Acceleration eXperiment (DAX) is one of the most recent experimental methods of performance characterization of new energetic materials. A cylindrical explosive charge accelerates a thin metallic disc and its velocity is measured continuously using photonic Doppler velocimetry. The detonation velocity is measured simultaneously. The DAX test can be used to obtain the Chapman-Jouguet (CJ) detonation pressure and to describe detonation products expansion using reduced amount of explosive. A series of DAX tests was performed at various charge diameters and disc thicknesses with Semtex 1 A plastic bonded explosive and sensitized nitromethane. The DAX-like evaluation was also applied to previously measured data of Semtex 1A and A-IX-1 explosives. The optimum disc thickness is determined by the disc to explosive mass ratio of 0.01e0.08. The repeatability of the Semtex 1 A detonation pressure results is about four times lower compared to the pressed and liquid explosives. [ABSTRACT FROM AUTHOR]

In this study, flow behavior in a meandering channel was investigated experimentally and numerically. The experiments were carried out for nine different cases on a channel consisting of 180° and 120° angle bends following successively. Measurements were conducted employing Acoustic Doppler Velocimetry (ADV) at 13 different points in the inner, middle, and outer bends of the sections located at significant bends along the channel. Depth-averaged velocity, velocity profiles, bed shear stress, and turbulence kinetic energy parameters were considered to understand the flow behavior in the meandering channel. A 1:1 scale numerical model of the experimental setup was generated using the Computational Fluid Dynamics (CFD) method through the verified FLOW-3D software (HYDRO 2022R1). It was found to be successful in estimating all parameters and was capable of investigating the flow behavior in the meandering channel. Additionally, a mesh independence study was performed, and four different turbulence models were compared. As a result, as the flow encountered the first meander in the channel, secondary flow occurred, and lateral momentum transfer took place. Therefore, velocity increased by approximately 30% from the first meander of 180° angles to the second meander of 120° angles. Therefore, the most critical zone was the inner bend of the 120-angle meander. [ABSTRACT FROM AUTHOR]

Velocity measurements of fast-moving objects are essential to a growing number of geotechnical applications. A photonic Doppler velocimeter (PDV) was configured to acquire the velocity–time history of a decelerating projectile from impact into soil through final burial. The PDV was setup using two independent lasers that were frequency shifted by approximately 0.2 GHz, which permitted recording low velocity data that are typically lost in homodyne configuration employing one laser only. Validation tests were carried out using a rotating target which verified the PDV measurements. The PDV was deployed in a vertical impact laboratory range to obtain deceleration records within carefully prepared soil targets. Two penetration tests into clayey sand targets that were performed by impacting conical projectiles are presented to demonstrate the repeatability of the experimental methodology. In this study, deceleration histories from impact at a velocity of 155 m/s were measured. Time-dependent depth of penetration and penetration resistance were calculated, with high fidelity, from the velocity–time records. The results were nearly identical for both tests for the velocity–time record, and it was possible to track the penetration velocity down to 20 m/s. This demonstrates that PDV measurements are well suited for measuring penetration resistance at ballistic velocities. [ABSTRACT FROM AUTHOR]

Introduction: Growth-restricted fetuses may have changes in their neuroanatomical structures that can be detected in prenatal imaging. We aim to compare corpus callosal length (CCL) and cerebellar vermian height (CVH) measurements between fetal growth restriction (FGR) and control fetuses and to correlate them with cerebral Doppler velocimetry in growth-restricted fetuses. Methods: This was a prospective cohort of FGR after 20 weeks of gestation with ultrasound measurements of CCL and CVH. Control cohort was assembled from fetuses without FGR who had growth ultrasound after 20 weeks of gestation. We compared differences of CCL or CVH between FGR and controls. We also tested for the correlations of CCL and CVH with middle cerebral artery (MCA) pulsatility index (PI) and vertebral artery (VA) PI in the FGR group. CCL and CVH measurements were adjusted by head circumference (HC). Results: CCL and CVH were obtained in 68 and 55 fetuses, respectively. CCL/HC was smaller in FGR fetuses when compared to control fetuses (difference = 0.03, 95% CI: [0.02, 0.04], p < 0.001). CVH/HC was larger in FGR fetuses compared to NG fetuses (difference = 0.1, 95% CI: [−0.01, 0.02], p = < 0.001). VA PI multiples of the median were inversely correlated with CVH/HC (rho = −0.53, p = 0.007), while CCL/HC was not correlated with VA PI. Neither CCL/HC nor CVH/HC was correlated with MCA PI. Conclusions: CCL/HC and CVH/HC measurements show differences in growth-restricted fetuses compared to a control cohort. We also found an inverse relationship between VA PI and CVH/HC. The potential use of neurosonography assessment in FGR assessment requires continued explorations. Plain Language Summary: In this study, we compared ultrasound measurements of several brain structures in fetuses with reduced or normal growth. We also evaluated the correlation of the size/length of these brain structures to blood flow of several blood vessels to the brain. We found that measurements of the small brain (CVH) are larger in pregnancies with growth problems. We also found that the blood flow of the vessel in the back side of the brain (vertebral artery [VA] Doppler) is inversely correlated with the CVH. These findings add to the literature on the use of ultrasound specifically to assess brain structures in pregnancies that are affected by growth problems. Deeper understanding of these associations may help establish which pregnancies with growth problems may need the most help later in life. [ABSTRACT FROM AUTHOR]

We demonstrate a flexible multichannel fiber-based imaging Doppler spectrometer to characterize plasmas in high intensity (≥1 × 1018 W/cm2) laser-plasma experiments at high repetition rates. This instrument collects data from ×21 different plasma locations combining optical fibers and a single imaging spectrometer. This diagnostic maps the plasma velocity evolution as a function of time with sub-pico-second resolution. Experimental results showing 2D velocity measurements of plasma with 20 μm spatial resolution are presented. Intensities of the order of 1018 W/cm2 were used to generate a plasma, while a much less intense, frequency doubled (400 nm), probe beam (1011 W/cm2) was used to measure the Doppler shift from the plasma critical surface. The instrument can be scaled to a larger number of channels (e.g., 100) still using a single spectrometer. [ABSTRACT FROM AUTHOR]

This work describes the development of a particle tracking velocimetry (PTV) algorithm designed to improve three-dimensional (3D), three-component velocity field measurements using a single plenoptic camera. Particular focus is on mitigating the longstanding depth uncertainty issues that have traditionally plagued plenoptic particle image velocimetry (PIV) experiments by leveraging the camera's ability to generate multiple perspective views of a scene in order to assist both particle triangulation and tracking. 3D positions are first estimated via light field ray bundling (LFRB) whereby particle rays are projected into the measurement volume using image-to-object space mapping. Tracking is subsequently performed independently within each perspective view, providing a statistical amalgamation of each particle's predicted motion through time in order to help guide 3D trajectory estimation while simultaneously protecting the tracking algorithm from physically unreasonable fluctuations in particle depth positions. A synthetic performance assessment revealed a reduction in the average depth errors obtained by LFRB as compared to the conventional multiplicative algebraic reconstruction technique when estimating particle locations. Further analysis using a synthetic vortex ring at a magnification of − 0.6 demonstrated plenoptic-PIV capable of maintaining the equivalent of 0.1–0.15 voxel accuracy in the depth domain at a spacing to displacement ratio of 5.3–10.5, an improvement of 84–89% compared to plenoptic-PIV. Experiments were conducted at a spacing to displacement ratio of approximately 5.8 to capture the 3D flow field around a rotor within the rotating reference frame. The resulting plenoptic-PIV/PTV vector fields were evaluated with reference to a fixed frame stereoscopic-PIV (stereo-PIV) validation experiment. A systematic depth-wise (radial) component of velocity directed toward the wingtip, consistent with observations from prior literature and stereo-PIV experiments, was captured by plenoptic-PTV at magnitudes similar to the validation data. In contrast, the plenoptic-PIV did not discern any coherent indication of radial motion. Our algorithm constitutes a significant advancement in enhancing the functionality and versatility of single-plenoptic camera flow diagnostics by directly addressing the primary limitation associated with plenoptic imaging. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the maternal-fetal hemodynamic effects after osteopathic manipulative treatment by measuring vital signs and Doppler velocimetry in third-trimester pregnant women. Materials and methods: This is a prospective study with pregnant women undergoing outpatient follow-up and hospitalized in a ward at Instituto Fernandes Figueira/Fiocruz, between August 2021 to August 2022, during the SARS-CoV-2 pandemic. This study was registered in REBEC under Register Number RBR-9q7kvg and approved by the ethics committee under number 32216620.0.0000.5269. The study population was composed of 51 pregnant women between 28 and 40 weeks of gestation, over 18 years of age, allocated in a single group. Pregnancies with multiple fetuses, malformations, premature rupture of the membrane, and active labor were excluded. The procedures evaluated maternal-fetal hemodynamics using three consecutive measures of ultrasound examination with Doppler velocimetry, and three maternal vital signs measured by an electronic blood pressure monitor. Results: Most vital signs changed after osteopathic treatment. However, only the systolic blood pressure (109.92 ±14.42 to 110.71±12.8, p = 0.033), diastolic blood pressure (79.8±11.54 to 77.57±9.44, p = 0.018) and heart rate (87.59±11.93 to 81.12±10.26, p = 0.000) in the sitting position, systolic blood pressure (110.75±13.26 to 108.59±13.07; p = 0.034) in the supine, and heart rate (83.22±11.29 to 80.39±11.0; p = 0.013) in left lateral decubitus reached statistical significance. The oximetry measures (98.55±0.64 to 98.67±0.68; p = 0.098) stayed stable during all three positions. All artery values remained stable after treatment, and no statistically significant difference was recorded in the artery results. Conclusion: Responses to osteopathic treatment in women in the third trimester of pregnancy did not affect uteroplacental and fetoplacental circulation. However, some maternal vital signs had statistically significant results, with a decrease in diastolic blood pressure and heart rate, and an increase in systolic blood pressure in the sitting position, a decrease of heart rate in the left lateral decubitus position, and systolic blood pressure in the supine position. All the results observed were maintained in the normal parameters. The study responses attest to the safety of using the osteopathic manipulative treatment for the fetus and for pregnant women with comorbidities. [ABSTRACT FROM AUTHOR]

Measurements of mass flow through a three-outlet spillway modeled after a scaled-down spillway were conducted. The inlet and channel leading up to the outlets were placed to lead the water toward the outlet at an angle. With this, measurements of the water level at three locations were recorded by magnetostrictive sensors. The volumetric flow rates for each individual outlet were recorded separately to study the differences between them. Additionally, Acoustic Doppler Velocimetry was used to measure water velocities close to the outlets. The conditions changed were the inlet volume flow rate and the flow distribution was measured at 90, 100, 110, and 200 L per second. Differences between the outlets were mostly within the error margin of the instruments used in the experiments with larger differences shown for the 200 L test. The results produced together with a CAD model of the setup can be used for verification of CFD methods. A simulation with the k-epsilon turbulence model is included and compared to earlier experiments and the new experimental results. Larger differences are seen in the new experiments. Differing inlet conditions are assumed as the principal cause for the differences seen. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the association and the potential value of prelabour fetal heart rate short‐term variability (STV) determined by computerised cardiotocography (cCTG) and maternal and fetal Doppler in predicting labour outcomes. Design: Prospective cohort study. Setting: The Prince of Wales Hospital, a tertiary maternity unit, in Hong Kong SAR. Population: Women with a term singleton pregnancy in latent phase of labour or before labour induction were recruited during May 2019–November 2021. Methods: Prelabour ultrasonographic assessment of fetal growth, Doppler velocimetry and prelabour cCTG monitoring including Dawes–Redman CTG analysis were registered shortly before induction of labour or during the latent phase of spontaneous labour. Main outcome measures: Umbilical cord arterial pH, emergency delivery due to pathological CTG during labour and neonatal intensive care unit (NICU)/special care baby unit (SCBU) admission. Results: Of the 470 pregnant women invited to participate in the study, 440 women provided informed consent and a total of 400 participants were included for further analysis. Thirty‐four (8.5%) participants underwent emergency delivery for pathological CTG during labour. A total of 6 (1.50%) and 148 (37.00%) newborns required NICU and SCBU admission, respectively. Middle cerebral artery pulsatility index (MCA‐PI) and MCA‐PI z‐score were significantly lower in pregnancies that required emergency delivery for pathological CTG during labour compared with those that did not (1.23 [1.07–1.40] versus 1.40 [1.22–1.64], p = 0.002; and 0.55 ± 1.07 vs. 0.12 ± 1.06), p = 0.049]. This study demonstrated a weakly positive correlation between umbilical cord arterial pH and prelabour log10 STV (r = 0.107, p = 0.035) and the regression analyses revealed that the contributing factors for umbilical cord arterial pH were smoking (p = 0.006) and prelabour log10 STV (p = 0.025). Conclusions: In pregnant women admitted in latent phase of labour or for induction of labour at term, prelabour cCTG STV had a weakly positive association with umbilical cord arterial pH but was not predictive of emergency delivery due to pathological CTG during labour. [ABSTRACT FROM AUTHOR]

The impact of turbulent coflows on the dynamics of turbulent twin round jets is investigated experimentally. Parallel twin jets, at three jet spacing values and two Reynolds number/jet-to-coflow velocity ratios, were released into turbulent coflows with two distinct levels of turbulence intensity. Velocity measurements were made using acoustic Doppler velocimetry. An increase in the coflow turbulence intensity leads to an earlier merging and combining of the jets and also accelerates the rate of decay with downstream distance of the mean centerline excess velocity of the jets. The mean velocity on the symmetry line, for different values of jet spacing, ratios of jet exit velocity to coflow mean velocity, and coflow turbulence intensity, is self-similar when scaled by the maximum mean velocity on the symmetry line and the corresponding streamwise distance. Moreover, as the turbulence level of the coflow intensifies, the turbulence intensity along the symmetry line of the jets increases. The longitudinal integral length scale on the symmetry line of the twin jets decreases as the coflow turbulence intensity increases. The energy spectra of the coflowing twin jets show that the turbulence in the coflow transfers the energy contained by the larger scales to the smaller scales at a greater rate than that which occurs for jets in a quiescent background. However, as the jet spacing increases, less energy is transferred to the smaller scales. [ABSTRACT FROM AUTHOR]

The vortices, backflow, and siltation caused by sediment-laden flow are detrimental to the safe and efficient operation of pumping stations. To explore the effects of water–sediment two-phase flow on the velocity field, vorticity field, and sediment distribution within intake structures, field tests and numerical simulations were conducted in this study with consideration for the sediment concentration, flow rate, and start-up combination. We applied a non-contact laser scanner and ultrasonic Doppler velocimetry to obtain the field data and reverse modeling of the three-dimensional model of the intake structure under siltation. A multiphase flow model based on the Euler–Euler approach combined with the k-ε turbulence model was adopted for numerical simulation under 10 working conditions, and the reliability was verified with field data. The results indicate that sediment promotes the evolution of coaxial vortices into larger-scale spiral vortices along the water depth, and the process of sediment deposition is controlled by the range, intensity, and flow velocity of the backflow zone. Furthermore, the maximum volume fraction of the near-bottom sediment increased by 202.01% compared to the initial state. The increase in flow rate exacerbates the turbulence of the flow field. Although the increase in sediment concentration benefits the flow diffusion, it further promotes sediment deposition. This study provides a new idea for modeling complex surfaces and considers different operating conditions. It can serve as a scientific reference for the structural optimization and anti-siltation design of similar water-conservancy projects. [ABSTRACT FROM AUTHOR]

Introduction: The objective of this study was to evaluate the association between fetal cardiac deformation analysis (CDA) and cardiac function with severe adverse perinatal outcomes in fetuses with isolated left congenital diaphragmatic hernia (CDH). Methods: CDA in each ventricle (contractility, size, and shape), evaluated by speckle tracking and novel FetalHQ software, and markers of cardiac function (E/A ratios, pulmonary and aortic peak systolic velocities, and sigmoid annular valve diameters), were evaluated in fetuses with isolated left CDH. Two evaluations were performed: at referral (CDA and function) and within 3 weeks of delivery (CDA). Severe adverse neonatal outcomes were considered neonatal death (ND) or survival with CDH-associated pulmonary hypertension (CDH-PH). Differences and associations between CDA, cardiac function, and severe adverse outcomes were estimated. Results: Fifty fetuses were included, and seventeen (34%) had severe adverse neonatal outcomes (11 ND and 6 survivors with CDH-PH). At first evaluation, the prevalence of a small left ventricle was 34% (17/50) with a higher prevalence among neonates presenting severe adverse outcomes (58.8 [10/17] vs. 21.2% [7/33]; p = 0.01; OR, 5.03 [1.4–19.1; p = 0.01]) and among those presenting with neonatal mortality (8/11 [72.7] vs. 9/39 [23.0%]; p = 0.03; OR, 8.9 [1.9–40.7; p = 0.005]). No differences in cardiac function or strain were noted between fetuses with or without severe adverse outcomes. Within 3 weeks of delivery, the prevalence of small left ventricle was higher (19/34; 55.8%) with a more globular shape (reduced transverse/longitudinal ratio). A globular right ventricle was significantly associated with ND or survival with CDH-PH (OR, 14.2 [1.5–138.3]; p = 0.02). Conclusion: Fetuses with isolated CDH at risk of perinatal death or survival with CDH-PH had a higher prevalence of a small left ventricle and abnormal shape of the right ventricle. [ABSTRACT FROM AUTHOR]

This study examines the S-characteristic, a key factor affecting the safe grid connection and operation of pumped-storage units, and its significant impact on the safety of pumped-storage power stations. We conducted numerical simulations and model experiments to investigate vortex motion characteristics in the vaneless space and runner passage of pump-turbines operating within the S-shaped region, along with an analysis of pressure pulsation characteristics. The accuracy of these simulations was validated through laser Doppler velocimetry experiments, and particle image velocimetry experiments were used to capture vortex motion in the vaneless space. We observed that vortices generated on the guide vane side follow the flow direction, blocking the guide vane passage, while those generated by runner blades move in the opposite direction. Employing an entropy production theory and the Liutex method, we investigated vortex distribution and hydraulic loss in the S-shaped region. The results show that reduced flow rates lead to significant vortices in the vaneless space and guide vane area, which become main contributors to energy loss in this region. These vortices, along with those in the runner passage, mainly arise from flow separation on blade and guide vane surfaces due to suboptimal inflow conditions. The study also identifies pressure fluctuations in the vaneless space, induced by a rotating stall, as the most significant pressure pulsation phenomenon, which significantly impacts the performance of the unit in both upstream and downstream directions. [ABSTRACT FROM AUTHOR]

Optical up-conversion photonic Doppler velocimetry (PDV) based on stimulated Brillouin Scattering (SBS) with an all-fiber link structure is proposed in this article. Because SBS limits the laser power transmitted by a fiber over long distances, the probe does not have enough outgoing light to reach the measured surface and cannot receive the signal light. Traditionally, SBS is avoided, but it is a phase-conjugated light and shifts down relative to the source light, so it can be used as a reference light in the laser interference structure to achieve up-conversion heterodyne velocimetry. Compared with general homodyne velocimetry (DPS), SBS-PDV naturally upconverts and has more interference fringes and higher resolution at low-speed measurement. In the gas multiple reflection impact compression experiment, the velocity measurement results of SBS-PDV and dual-laser heterodyne Velocimetry (DLHV) are basically consistent, and the accuracy is better than 0.8%. Due to its coaxial heterodyne optical path, this kind of photonic Doppler velocimetry is suitable for low-velocity and long-distance practical applications in the field of shock wave physics. [ABSTRACT FROM AUTHOR]

Composite traits involve multiple components that, only when combined, gain a new synergistic function. Thus, how they evolve remains a puzzle. We combined field experiments, microscopy, chemical analyses, and laser Doppler vibrometry with comparative phylogenetic analyses to show that two carnivorous Nepenthes pitcher plant species independently evolved similar adaptations in three distinct traits to acquire a new, composite trapping mechanism. Comparative analyses suggest that this new trait arose convergently through “spontaneous coincidence” of the required trait combination, rather than directional selection in the component traits. Our results indicate a plausible mechanism for composite trait evolution and highlight the importance of stochastic phenotypic variation as a facilitator of evolutionary novelty. [ABSTRACT FROM AUTHOR]

Noninvasive optical measurements of the shockwave propagation velocity using multiple pulse illumination allow deducing the shockwave pressure amplitude through Hugoniot relations and an appropriate equation of state of the medium. This technique is particularly useful for spatially resolved measurements near the shockwave emission site. Due to diffraction, however, a shockwave front can significantly change its morphology, rendering precise velocity measurements non-trivial. As solution we propose a wave front evolution (WaFE) velocimetry technique, which applies Huygens principle. We take a shadowgraph of the wave front at subsequent times as initial condition for the acoustic Helmholtz equation and numerically propagate the fronts in time. From the instance of time, when two subsequently taken wave front shadows numerically interfere and form one sharp wave front, the local shock velocity is obtained and the local shock pressure amplitude measured. With artificial test images, it is shown that this technique has excellent sub-pixel accuracy, robustness to noise, and can work with low contrast images and even overlapping and interfering wave fronts. The software is made available freely and can be applied to general shock front velocity measurements. We apply WaFE to determine the anisotropic shockwave emission from an elongated laser-induced plasma in water from shadowgraphs of the shockwave front imaged four times onto the same camera frame using multiple pulse illumination at a repetition rate of 60 MHz. The direction dependence of attenuation of the shockwave pressure amplitude is measured at distances of 50–300 μm to the plasma. [ABSTRACT FROM AUTHOR]

We experimentally study miscible displacement flows of a light Newtonian fluid by a heavy viscoplastic fluid, in a vertical pipe with a large aspect ratio ( δ − 1 ≫ 1). We use camera imaging, laser-induced fluorescence, and ultrasound Doppler velocimetry techniques, to capture and process data. Four dimensionless parameters, namely, the Reynolds (Re), Bingham (B), viscosity ratio (M), and densimetric Froude (Fr) numbers (or their combinations), mainly govern the flow dynamics. We identify and characterize three distinct flow regimes, including plug, separation, and mixing regimes, while we describe each regime's dynamics in detail, particularly in terms of the velocity and concentration fields as well as the displacement front velocity. In addition, we analyze the plug regime concerning the residual wall layers, the separation regime in terms of the separation dynamics, spatiotemporal separation zone, and viscoplastic layer thinning, and the mixing regime regarding the mixing index and macroscopic diffusion. Finally, we develop a simplified model to help delineate the flow regime classification, in the plane of R e / F r 2 and M. [ABSTRACT FROM AUTHOR]

Cystic endometrial hyperplasia (CEH)–pyometra complex is the most common uterine infection in adult and elderly bitches and can cause renal dysfunction. The aim of this study was to measure and compare urinary creatinine, urea, symmetric dimethylarginine (SDMA), urinary protein–creatinine ratio (UPC), measurement of systolic blood pressure (SBP), and Doppler velocimetry of renal arteries in patients with CEH–pyometra complex before and after an average of 6 months of treatment, evaluating the possibility of the changes persisting. The evaluation was conducted at two moments: M1 (at the diagnosis of CEH–pyometra, n = 36) and M2 (after an average of six months of treatment, n = 16). For the control group, eight bitches with no changes in blood tests or history of conditions underwent Doppler ultrasound evaluation of the renal arteries. At both M1 and M2, we measured creatinine, urea, and serum SDMA, UPC, SBP, and Doppler ultrasound of the renal arteries. Patients were evaluated according to the following groups: azotemic (AZO) and non‐azotemic (NAZO), and open and closed cervix pyometra. The parameters were compared between animals present in both moments presented as M1R (bitches that were in M1 and M2) and M2. Statistical significance was considered when p <.05. The medians found for creatinine in M1 were as follows: 1.15 mg/dL, being 1.8 mg/dL for AZO (12/36) and 0.95 mg/dL for NAZO (24/36); and in M2: 0.85 mg/dL (16/16), being 1.15 mg/dL for AZO (4/16) and 0.8 mg/dL for NAZO (12/36). For urea, in M1 it was 36 mg/dL (32/36), with AZO being 103 mg/dL (11/32) and 33 mg/dL in NAZO (21/32); and in M2 32 mg/dL (16/ 16), being 29 mg/dL for AZO (4/36), and 31 mg/dL for NAZO (3/15). The median SDMA measured in M1R was 17 μg/dL (15/16), with AZO being 31 μg/dL (3/15), and NAZO being 16.5 μg/dL (12/15); and in M2, SDMA was 12 μg/dL (16/16), with AZO being 12.5 μg/dL (4/16), and NAZO being 12 μg/dL (12/16). The median UPC measured in M1 was 1.15 (10/36), with AZO being 0.25 (1/10), and NAZO being 1.38 (9/10); and in M2, it was 0.2 (13/16), being 0.1 in AZO (4/13), and 0.2 (9/16) in NAZO. For SBP, in M1, it was 118 mmHg (30/36), with AZO being 102 mmHg (10/30) and 133 mmHg in NAZO (20/30); and in M2 142.5 mmHg (12/16), being 155 mmHg for AZO (4/12), and 140 mg/dL for NAZO (8/12). When comparing animals with open and closed cervixes, a difference was found between SDMA measurements (p =.001). There was a distinction between PI and RI of the left and right kidneys consecutively (p =.007; p =.033; p =.019; p =.041). Correlations found in M1: SDMA × PI RIM DIR (r = 0.873; p =.002), SDMA × PSV RIM ESQ (r = 0.840; p =.004), SDMA × EDV RIM ESQ (r = 0.675; p =.046). With this study, we conclude a return to normality of renal biomarkers and clinical parameters after six months. Yet, there is a persistence of Doppler velocimetric measurements between the two moments. Thus, this parameter is not suitable for identifying and classifying chronic kidney injury in bitches with pyometra. [ABSTRACT FROM AUTHOR]

A high-throughput experimental setup was used to characterize initiation threshold and growth to detonation in the explosives hexanitrostilbene (HNS) and pentaerythritol tetranitrate (PETN). The experiment sequentially launched an array of laser-driven flyers to shock samples arranged in a 96-well microplate geometry, with photonic Doppler velocimetry diagnostics to characterize flyer velocity and particle velocity at the explosive–substrate interface. Vapor-deposited films of HNS and PETN were used to provide numerous samples with various thicknesses, enabling characterization of the evolution of growth to detonation. One-dimensional hydrocode simulations were performed with reactions disabled to illustrate where the experimental data deviate from the predicted inert response. Prompt initiation was observed in 144 μm thick HNS films at flyer velocities near 3000 m/s and in 125 μm thick PETN films at flyer velocities near 2400 m/s. This experimental setup enables rapid quantification of the growth of reactions in explosive materials that can reach detonation at sub-millimeter length scales. These data can subsequently be used for parameterizing reactive burn models in hydrocode simulations, as discussed in Paper II [D. E. Kittell, R. Knepper, and A. S. Tappan, J. Appl. Phys. 131, 154902 (2022)]. [ABSTRACT FROM AUTHOR]

Photonic Doppler velocimetry and digital high-speed shadowgraphy have been used to characterize the chemical reaction zone parameters of pressed trinitrotoluene (TNT) samples with an initial density of 1.568 g cm − 3 . Comparison of the nanosecond time-resolved particle velocity histories of the free surfaces of detonating charges in air and light vacuum and of the interfaces between TNT detonation products and lithium fluoride or polymethyl methacrylate windows allow one to bracket the von Neumann spike pressure between 24.8 and 28.8 GPa. Our velocity waveforms confirm the two-step reaction pathway already observed in TNT, triaminotrinitrobenzene (TATB), and nitromethane, with a first fast energy release over 80 ns followed by a slower release over 250 additional ns. We consider the end of the first release zone as the locus of the Chapman–Jouguet (CJ) state, and the CJ pressure thus lies between 17.6 and 17.7 GPa. The energy release is not completed in this Jouguet plane but only after about ≈ 280 ns when the carbon cluster formation process ends. This corresponds to both the end of the slow release part of the interface velocity profiles and to the moment at which the free surface velocity profiles reach their maximum. Our shadowgraphy images confirm that carbon formation occurs very rapidly after the detonation breakout, in good agreement with previous time-resolved small-angle x-ray scattering measurements. The comparison with similar results previously obtained on TATB allows one to further highlight their similarities, which mainly result from their excess carbon production at late times. [ABSTRACT FROM AUTHOR]

We present a new study of Jupiter's atmosphere dynamics using for the first time the extremely high-resolution capabilities of VLT/ESPRESSO to retrieve wind velocities in Jupiter's troposphere, with a dedicated ground-based Doppler velocimetry method. This work is primarily a proof-of-concept for retrieving Jupiter's winds using VLT/ESPRESSO Doppler velocities. These results are complemented by a re-analysis of Cassini's data from its fly-by of Jupiter in December 2000, performing cloud tracking at visible wavelengths, for cross comparison with Doppler velocimetry results, along with previous cloud-tracking results. We explore the effectiveness of this refined method to measure winds in Jupiter, using high-resolution spectroscopy data obtained from ESPRESSO observations performed in July 2019, with a Doppler velocimetry method based on backscattered solar radiation in the visible range. Coupled with our ground-based results, we retrieved a latitudinal and longitudinal profile of Jupiter's winds along select bands of the atmosphere. Comparing the results between cloud-tracking methods, based on previous reference observations, and our new Doppler velocimetry approach, we found a good agreement between them, demonstrating the effectiveness of this technique. The winds obtained in this exploratory study have a two-fold relevance: they contribute to the temporal and spatial variability study of Jupiter's troposphere dynamics, and the results presented here also validate the use of this Doppler technique to study the dynamics of Jupiter's atmosphere and pave the way for further exploration of a broader region of Jupiter's disk for a more comprehensive retrieval of winds and to evaluate their spatial and temporal variability. [ABSTRACT FROM AUTHOR]

In the traditional X-ray pulsar Doppler velocimetry approach, a single pulsar only provides the velocity information of spacecraft in the line-of-sight (LOS) direction of a pulsar. Theoretically, we prove that the spacecraft velocity error in any direction can distort the X-ray pulsar profile in orbit around Jupiter. Moreover, using singular value decomposition (SVD), we find that the observability of velocities in both the maximal and middle singular directions is far better than that of the minimal one. Based on theoretical analysis results, we propose a two-dimensional Doppler velocimetry approach using a single X-ray pulsar to provide more velocity information for spacecraft. Firstly, we use SVD to give two well-observable singular directions for velocity estimation. And then, to eliminate duplicate computations in the accumulative process of X-ray pulsar signals, we build the piecewise complete dictionary of accumulated pulsar profiles, which has no identical accumulated pulsar profile. Finally, using the chi-square value of X-ray pulsar sup-profiles as an evaluation standard, we develop the two-level velocity estimation based on dictionary folding (DF) to measure the two-dimensional Doppler velocity. Experimental results demonstrate that compared with the traditional one-dimensional pulsar velocimetry approach, the two-dimensional Doppler velocimetry approach using a single X-ray pulsar provides more velocity information and is more robust to the initial velocity error. The accuracies of velocities in both two singular directions reach 0.3 m/s. In addition, compared with the traditional epoch folding, the elapsed time of the DF reduce by more than 70% and gets 4 min. • We develop a new idea that provides two-dimensional Doppler velocity for spacecraft. • We prove the propagation property of velocity error in the orbit around a planet. • Two directions for Doppler velocity are calculated by singular value decomposition. • We build the piecewise complete dictionary to remove numerous duplicate computations. • We propose dictionary folding to substitute for epoch folding and improve real-time. [ABSTRACT FROM AUTHOR]

Combined wave-current turbulent characteristics are investigated over a rough bed comprising of hemispheres positioned at different spacings (p/r = 4, 6, and 8; p is the patch distance and r is the height of the hemisphere) in terms of time-space averaged (double-averaged) flow components. An Acoustic Doppler Velocimetry was used to measure the instantaneous velocity components for all background flow cases that comprised current-only flow and wave superimposed on current (wave frequency 0 Hz, 1 Hz, and 2 Hz). This study attempts to characterize the double-averaged velocity, relative and formed induced turbulence intensity, and Reynolds shear stress for the specific flow layers due to the interaction of wave-current flow over the hemispherical rough bed. The study further explores how these parameters are modulated with the change in spacing between the roughness elements. The relative contribution of the different turbulent busting events is analyzed for the different positions with respect to the hemispherical elements. Results show that sweep and ejection are the major contributors to all flow conditions and roughness cases explored herein. Furthermore, the anisotropic structure of turbulence due to the superposition of waves for different rough bed conditions is explored in the double-averaged perspective. [ABSTRACT FROM AUTHOR]

Objectives: There is a paucity of literature providing evidence‐based guidelines for the management of large placental chorioangioma (≥ 4 cm in diameter). The objectives of this study were to compare outcomes between patients managed expectantly and those undergoing in‐utero intervention and to describe the different in‐utero techniques used for cessation of blood flow to the tumor and the associated outcome. Methods: This was a retrospective cohort study of 34 patients referred for the management of large placental chorioangioma in a single center between January 2011 and December 2022, who were managed expectantly or underwent in‐utero intervention. In‐utero intervention was performed when the fetus developed any signs of impending compromise, including high combined cardiac output (CCO), worsening polyhydramnios or abnormal fetal Doppler velocimetry findings. Interventions included radiofrequency ablation (RFA), interstitial laser ablation (ILA) and single‐port or two‐port fetoscopic laser photocoagulation (FLP). Treatment selection was dependent on the proximity of the tumor to the umbilical cord insertion (UCI) and placental location. The two‐port technique was performed in patients with a chorioangioma with large feeding vessels (≥ 3 mm) located in the posterior placenta, in which one port was used for occlusion using bipolar forceps and the other port was used for laser photocoagulation of the feeding vessels downstream. The single‐port technique was used for chorioangioma with small feeding vessels (< 3 mm) located in the posterior placenta. ILA or RFA was performed in cases with an anterior placenta. Supportive treatments, including amnioreduction and intrauterine transfusion (IUT), were performed for worsening polyhydramnios and suspected fetal anemia based on middle cerebral artery Doppler flow studies, respectively. Comparative statistical analysis between cases undergoing expectant management vs in‐utero intervention was performed. Descriptive details were provided for patients who underwent in‐utero intervention. Results: Thirty‐four cases of large chorioangioma were evaluated, of which 25 (73.5%) were managed expectantly and nine (26.5%) underwent intervention. The frequency of polyhydramnios was significantly higher in the intervention group compared with the expectant‐management group (66.7% vs 8.0%, P < 0.001). The live‐birth rate among expectantly managed cases with large chorioangioma was significantly higher compared with that in cases that underwent in‐utero intervention (96.0% vs 62.5%, P = 0.01). In the intervention group, preoperative CCO was elevated in all cases with available information and preoperative hydrops was present in 33.3% (3/9) of cases. One patient experienced fetal demise following IUT prior to planned FLP. Among the remaining eight patients, four underwent two‐port FLP, two underwent single‐port FLP, one underwent ILA and one underwent both ILA and RFA. All three cases in which hydrops was present at the time of intervention resulted in fetal demise. Conclusions: In‐utero interventions aimed at cessation of blood flow in the feeding vessels are a therapeutic option for the management of cases with large chorioangioma. The two‐port percutaneous technique appears to improve the efficiency of FLP when a large chorioangioma with large feeding vessels is located in the posterior placenta. We propose that in‐utero interventions for large chorioangioma should be initiated prior to the development of fetal hydrops. © 2023 International Society of Ultrasound in Obstetrics and Gynecology. [ABSTRACT FROM AUTHOR]

The physics of shock-induced ejection is a crucial phenomenon in the field of shock compression science and technology. Limited by loading methods, the previous research primarily focused on the physics of ejecta induced by single shockwave, with few data available on multiple shockwave loading conditions. To solve this problem, we proposed a double shockwave production method based on the high-intensity laser facility, which allows the interval time between the shock waves to be adjusted in the nanosecond to microsecond timescale. Meanwhile, we applied loading techniques to study the ejection behavior of metal tin and integrated photonic doppler velocimetry and high-energy x-ray radiography technology to observe the ejection process. By comparing the experimental results for single and double shockwave, the multiple shock-induced ejection features have been clearly confirmed. Our experimental results provide valuable insight into the behavior of ejecta under multiple shockwave loading conditions, which is of great significance for deepening our understanding of the ejection mechanism. [ABSTRACT FROM AUTHOR]

This research work focuses on the wake flow region of a cylinder with a spoiler on a rough bed under steady flow conditions. The acoustic Doppler velocimetry was used for the measurement of three-dimensional velocity data for two Reynolds numbers in a fully developed turbulent flow around the cylinder with a spoiler. The mean flow velocities, second-order turbulence structures, and conditional statistics were investigated in the wake region of the spoilered cylinder. The flow was separated from the spoiler with the formation of two shear layers between free surface flow and recirculating flow. It is observed that the flow is reattaching to the bed at 11D irrespective of the Reynolds number. Downstream of the cylinder, the mean velocity distributions are asymmetric due to the wall–wake effect, and the point of inflection is observed for each velocity profile at z = 0.40ẟ. The turbulence intensities, Reynolds stresses, and TKE are highly enhanced in the wake region of the cylinder as compared to their respective upstream values for both runs. The turbulence intensities, Reynolds normal stresses, Reynolds shear stresses, and turbulent kinetic energy are attaining peaks at z = 0.4 ẟ for all the streamwise locations, and the peaks are found to be highest at x = 10D. The quadrant analysis results indicate that the sweeps are dominating bursting events in the inner and intermediate layers, while ejections are dominating in the outer layer of the wake region. As the hole size, H increases ejections stress fraction rises as compared to that of the sweeps in the wake region for z = 0.2–0.7 h. [ABSTRACT FROM AUTHOR]

A new subsonic blower wind tunnel design has been studied both numerically and experimentally; it is also referred to as "blower" wind tunnel. This paper is initially aimed to address each sequential stage of the wind tunnel design process. Rather than applying the standard method of modelling solely the flow in the test section, a large-scale CFD model of the whole wind tunnel was employed. The loss of every constituent element was calculated and then all the losses are added up to determine the power needed for the wind tunnel operation which is used as "intake fan" boundary conditions in the CFD model. Then, flow uniformity and turbulent intensity measurements in an empty test section using a pitot static tube and hot wire anemometer (HWA) were introduced to validate the CFD results. The results showed that flow quality was significantly affected by flow conditioners (uniformity devices) (honeycomb and mesh screens) in the settling chamber and wide-angle diffuser. Investigations were also conducted to evaluate the flow deficit in the wake area behind a convex hump model using both HWA and particle image velocimetry PIV. This was additional experimental tests carried out to validate the suitability of the wind tunnel designed for aerodynamic research. [ABSTRACT FROM AUTHOR]

To determine the parameters of equation of state for detonation products of the HNS-based explosive PBX-1, the plane wave lens and the photonic Doppler velocimetry (PDV) were used to measure the free surface velocity histories of metal plates driven by the PBX-1 explosives. The explosive samples had diameters of 6 mm and different lengths. According to the experimental results, the detonation velocity of PBX-1 is about 6 798.2 m/s, and the effective explosive volume is obviously affected by the ratio of length to diameter of explosive sample. Compared with the sample with the ratio equal to 1, the effective explosive volume of the sample with the ratio equal to 2, leads to a lower maximum plate velocity. The plate driven by the longer explosive sample is less affected by the initiation boundary of plane wave lens. Therefore, the experimental result obtained by the longer explosive sample was used to determine the detonation products' parameters of equation of state by numerical simulation. The simulation showed that the simulated free surface velocity history is in good agreement with the experimental result. The obtained detonation products' parameters of equation of state provides fundamental data for reliability assessment of slapper detonator. [ABSTRACT FROM AUTHOR]

Spatial acuity is a fundamental property of any sensory system. In the case of the somatosensory system, the two-point discrimination (2PD) test has long been used to investigate tactile spatial resolution. However, the somatosensory system comprises three main mechanoreceptive channels: the slowly adapting channel (SA) responds to steady pressure, the rapidly adapting channel (RA) responds to low-frequency vibration, and the Pacinian channel (PC) responds to high-frequency vibration. The use of mechanical stimuli in the classical 2PD test means that previous studies on tactile acuity have primarily focussed on the pressure-sensitive channel alone, while neglecting other submodalities. Here, we used a novel ultrasound stimulation to systematically investigate the spatial resolution of the two main vibrotactile channels. Contrary to the textbook view of poor spatial resolution for PC-like stimuli, across four experiments we found that high-frequency vibration produced surprisingly good spatial acuity. This effect remained after controlling for interchannel differences in stimulus detectability and perceived intensity. Laser doppler vibrometry experiments confirmed that the acuity of the PC channel was not simply an artifact of the skin's resonance to high-frequency mechanical stimulation. Thus, PC receptors may transmit substantial spatial information, despite their sparse distribution, deep location, and large receptive fields. [ABSTRACT FROM AUTHOR]

Off-design operations, such as speed-no-load (SNL), are damaging conditions for reaction hydraulic turbines such as Francis turbines. Identification and characterization of the flow phenomena in off-design condition can be used to assess their effects on the turbine residual life or to develop mitigation strategies. In turn, that could lead to an improved operational flexibility and to the decrease of maintenance costs and downtime of turbines. However, technical difficulties complicate performing flow measurements at the runner inlet of Francis turbines, where some damaging flow phenomena appear to occur in SNL conditions. This study presents a novel methodology, involving several technical developments, for performing stereoscopic endoscopic particle image velocimetry measurements at the inlet of a Francis turbine model. It details solutions for the efficient use of camera endoscopes and laser endoscopes in confined and watertight spaces. This paper also presents the results of time-resolved, three-component velocity measurements on planes covering part of the vaneless space between the guide vanes and the runner and the first part of the runner interblade channels in no-load and deep-part load conditions. [ABSTRACT FROM AUTHOR]

An experimental apparatus using synthetic jets to generate zero mean flow homogeneous isotropic turbulence (HIT) in the center of a cubic water tank is presented. Pumps drive jets at the corners and midpoints of the tank edges, producing center-facing flow to generate turbulence. The array of synthetic jets is controlled by a random forcing algorithm (Variano et al. in Exp Fluids 37:613–615, 2004) to optimize generation of turbulence while minimizing mean and secondary flows. We explore different combinations of mean percentage of jets on, Φ on , mean on-time, T on , and pump outlet velocity, V P , to determine their respective roles in turbulence generation. Particle image velocimetry (PIV) and acoustic Doppler velocimetry (ADV) are used to measure the velocity in the central isotropic region of the tank to determine turbulence statistics including mean velocities, mean flow strength, turbulent kinetic energy, spectra, integral scales, dissipation rates, Kolmogorov scales, Taylor microscales, and the Taylor-scale Reynolds number. We identified a range of input parameters to vary energy and length scales of the flow while maintaining homogeneity and isotropy in the central core of the facility. Magnitudes of the Taylor-scale Reynolds number ranged from 68 to 176 in the apparatus. Negligible mean recirculations were found, with mean flow strength values ranging from 1.26 to 2.99%, while ratios of root mean square turbulent velocities remained between 0.93 and 0.98, indicating a high degree of isotropy. [ABSTRACT FROM AUTHOR]

A differential multi-frequency laser Doppler velocimetry is demonstrated, utilizing the synchronized multimode of a mode-locked distributed Bragg reflector laser. This scheme enables the simultaneous detection of multiple Doppler frequency shifts. Multiple differential Doppler shifts of 0.6 Hz, 1.3 Hz, and 1.9 Hz are obtained, with an average speed of 3.677 mm/s and a standard deviation of 0.122 mm/s, demonstrating a cross-referenced velocity measurement capability. The measurement results are also compared with the dual-frequency laser Doppler velocimetry scheme using electro-optical modulation. [ABSTRACT FROM AUTHOR]

Laser Doppler velocimetry (LDV) based on a differential laser Doppler system has been widely used in fluid mechanics to measure particle velocity. However, the two outgoing lights must intersect strictly at the measurement position. In cross-interface applications, due to interface effects, two beams of light become easily disjointed. To address the issue, we present a laser velocimeter in a coaxial arrangement consisting of the following components: a single-frequency laser (wavelength λ = 532 nm) and a Twyman–Green interferometer. In contrast to previous LDV systems, a laser velocimeter based on the Twyman–Green interferometer has the advantage of realizing cross-interface measurement. At the same time, the sensitive direction of the instrument can be changed according to the direction of the measured speed. We have developed a 4000 m level laser hydrothermal flow velocity measurement prototype suitable for deep-sea in situ measurement. The system underwent a withstand voltage test at the Qingdao Deep Sea Base, and the signal obtained was normal under a high pressure of 40 MPa. The velocity contrast measurement was carried out at the China Institute of Water Resources and Hydropower Research. The maximum relative error of the measurement was 8.82% when compared with the acoustic Doppler velocimeter at the low-speed range of 0.1–1 m/s. The maximum relative error of the measurement was 1.98% when compared with the nozzle standard velocity system at the high-speed range of 1–7 m/s. Finally, the prototype system was successfully evaluated in the shallow sea in Lingshui, Hainan, with it demonstrating great potential for the in situ measurement of fluid velocity at marine hydrothermal vents. [ABSTRACT FROM AUTHOR]

To improve the global optimization ability and convergence speed of the swarm intelligence algorithm, we proposed a new swarm intelligence optimization algorithm, namely the Oryctolagus cuniculus algorithm. This includes five mechanisms: the determination of safety zones, the cave escape, the agglomeration of Oryctolagus cuniculi, the maintenance of the Oryctolagus cuniculus king, and the zone competition. Each solution is represented by each Oryctolagus cuniculus's position (including zone number and specific location number). The grass density and safety index at the location of the Oryctolagus cuniculus represents its fitness value. The determination of safety zones implies that predators such as eagles hunt Oryctolagus cuniculi in dangerous zones, and the zone without predators is considered a safety zone. The cave escape refers to the act of Oryctolagus cuniculi using a connected cave system to flee from a dangerous zone and reach a secure zone, thereby evading potential predators. We select the Oryctolagus cuniculus with higher fitness values as the king of each zone, and the Oryctolagus cuniculi gather towards the Oryctolagus cuniculus king. This mechanism ensures that Oryctolagus cuniculus mainly searches in zones with abundant grass and quickly finds the optimal solution. In the maintenance of the Oryctolagus cuniculus king, we choose the one with higher fitness values as the Oryctolagus cuniculus king. Zone competition is induced by an increase in the number of Oryctolagus cuniculi in zones with abundant grass by ordering the fitness values of each zone, and vice versa. We apply the Oryctolagus cuniculus algorithm to the inversion method of the asteroid spectra reflectance template. The experimental results show that compared with artificial rabbit optimization, this algorithm has a faster rate of convergence and better solution, effectively screens the reflectance template, and improves the Doppler difference velocimetry accuracy. In addition, the application of the Oryctolagus cuniculus algorithm to the knapsack problem also performs effectively. [ABSTRACT FROM AUTHOR]

This experimental study aims to investigate the characteristics of turbulent flow in channels with vegetated banks and varying channel width under the condition of the incipient motion of bed material. The natural reeds were used as emergent vegetation on the sidewalls of a laboratory flume. In total, nine experimental runs have been conducted with different experimental setups by using three different particle sizes of bed material and three different channel bed slopes. An Acoustic Doppler velocimetry (ADV) was used to acquire velocity components in three directions. The results of this study indicate that the streamwise velocities have the maximum and minimum values at the cross sections with the narrowest and widest width, respectively. When the aspect ratio is less than 5, the maximum velocity occurs below the water surface, due to presence of the secondary currents. It is found that, at all measurement points, the distribution of the Reynolds shear stress has a Z-shaped profile owing to presence of vegetation on the channel sidewalls. By extrapolating the profiles for flow velocity and Reynolds shear stress towards the surface of the channel bed, the near-bed incipient velocities and the corresponding shear stresses for the incipient motion have been determined. By increasing the channel bed slope, the estimated near-bed parameters for all particle sizes decreased, indicating the dominance of the gravity effect over the pressure gradient effect. It was also observed that the Shields method was invalid for assessing the incipient motion of bed material in the presence of vegetation on the sidewalls of a channel that has a varying width. [ABSTRACT FROM AUTHOR]

Background: Pre-existing hypertension, renal disease, diabetes mellitus, Obstructive Sleep Apnea, thrombophilia, and autoimmune disease all enhance the chance of developing hypertensive disease during pregnancy by decreasing uteroplacental blood flow. Women with a history of preeclampsia, HELLP syndrome, twin pregnancies or other multiple pregnancies, a BMI >30, autoimmune disease, being over 35 years old, being first-time mothers, or having a sister or mother who had hypertension during pregnancy are at an increased risk of developing hypertensive disorder of pregnancy and preeclampsia. Objectives: • To evaluate the screening efficacy of urinary calcium creatinine ratio versus Doppler study in predicting pre-eclampsia. • To study that low urinary calcium creatinine ratio (UCCR) of < 0.04 in asymptomatic pregnant women association with subsequent development of pre-eclampsia. • To study the usefulness of uterine artery Doppler velocimetry as a predictor for preeclampsia before 20 weeks in asymptomatic pregnant women. Material & Methods: Study Design: Hospital based observational study. Study area: Department of Obstetrics & Gynecology, in a tertiary care teaching hospital. Study Period: April 2022 – March 2023. Study population: Normotensive nonproteinuric pregnant women less than 20 weeks attending the outpatient as well as antenatal ward. Sample size: Study consisted a total of 100 subjects. Sampling Technique: Simple Random technique. Study tools and Data collection procedure: A hospital based prospective comparative study was conducted among a group of 100 normotensive nonproteinuric women 11 to 14 weeks attending the outpatient as soon as antenatal ward in tertiary care teaching hospital over a period of one years. They are subjected to a detail history and general examination. Results: Out of 100 women, 33 had abnormal PI at 11-14 weeks and out of which 24 developed Pre-Eclampsia. The sensitivity is 100% and specificity are 88.2% positive predictive value is 72.7%and NPV is 100% and its association between preeclampsia was statistically significant (p value<0.0001). Out of 100 women, 58 had abnormal PI at 16-20 weeks and out of which 23 developed Pre-Eclampsia. The sensitivity is 95.8%and specificity are53.9%, positive predictive value is 39.7 %and negative predictive value is 97.6% and its association between preeclampsia was statistically significant (p value<0.001). Conclusion: We conclude that PI at 11-14 weeks and 16 – 20 weeks was found to be the better predictor of Preeclampsia compared to UCCR with better sensitivity, specificity and diagnostic efficacy. We recommend using PI at 11-14 weeks as the predictive tool to predict the development of preeclampsia. [ABSTRACT FROM AUTHOR]