Volcanic supersonic jets: an experimental study of the effect of particles on the shock cell structure and acoustic emissions.

<p>Explosive volcanic eruptions eject a mixture of gas and pyroclasts into the atmosphere at a range of velocities. Directly above the vent, in the gas-thrust region, a supersonic jet may be generated that strongly controls the eruptive dynamics. To improve our quantitative understanding of volcanic supersonic jets, the effect on particles within them, and their acoustic emission, we have performed small-scale explosive eruptions in the laboratory using a shock-tube. The shock-tube is composed of 3 parts, a bottom (5.6 m long, elevated pressure) and a top (48mm long, ambient pressure) plexiglass cylinder (5 mm inner diameter), separated by an electrovalve.</p><p>We have run experiments using ambient air as gas and sand, with diameter between 0.1 and 0.3 mm, as particles. The gas volume was fixed while the pressure ratio (the shock-tube reservoir to ambient pressure ratio) was varied from about 4 to 8.4 to obtain supersonic flows. During the experiments, the jet was recorded with a high-speed camera operating at 34660 fps, and the resulting noise acoustic emission with microphones (6 Hz-140 kHz; 1000 kfps) positioned at 90° from the jet axis.</p><p>Among the acoustic signals produced by a supersonic jet (jet noise) we have particularly focussed on the broad-band shock noise (BBSN) that is emitted by the interaction between shock cells and the turbulence in the jet. We estimated the jet velocity using an acoustic model based on the identification of the peak frequency of the BBSN. We also identified the BBSN frequency and its variation over time by applying the complex Morlet wavelet transformation. As expected, the BBSN frequency is inversely proportional to the gas velocity. Concerning the video recording, we analysed the shock cells behaviour and their temporal oscillation due to the presence of particles. Finally, the particle ejection rate was calculated in every video frame.</p><p>We found that the acoustic signal and shock cells are influenced by the presence of particles. In fact, fluctuations in particle concentration are well visible and decelerate the flowing gas. As a consequence, there is a temporary decrease of the stand-off-distance between the vent and the first shock-cell and concurrent rise of the BBSN frequency. We noticed, in some cases, that the shock-cells disappear during a short time interval. The BBSN frequency and the stand-off-distance behaviour over time follow the oscillation of the particle ejection rate confirming their sensitivity to particle load variation.</p><p>The future prospectives of this embryonal study could lead to new instruments for determining either the amount of pyroclasts inside the volcanic jets and their exit velocity on the basis of the recorded acoustic signals.</p>

Central hemodynamic effects in patients with chronic coronary syndrome after long-term ivabradine therapy

Objectives We sought to assess central hemodynamic effects in 23 patients (18 male, 5 female) with a resting heart rate (HR) of ≥70 beats per minute (bpm) and chronic coronary syndrome after long-term ivabradine therapy (6 months) by cardiac magnetic resonance (CMR). Methods and results In a cross-over design, all patients were treated with ivabradine (Iva, 7.5 mg bid) and placebo for 6 months each. CMR was performed three times (at baseline, after 6 and 12 months) to determine left ventricular (LV) function parameters, including end-diastolic and end-systolic volumes (EDVi, ESVi), stroke volume (SVi) and ejection fraction (EF) as well as volume-time curve (VTC) parameters, including peak ejection rate (PER), peak ejection time (PET), peak filling rate (PFR), peak filling time from ES (PFT), peak ejection rate normalized to EDV (PER/EDV) and peak filling rate normalized to EDV (PFR/EDV) for global LV function (systolic and diastolic) assessment. Flow measurements of the ascending aorta were performed with phase-contrast velocity imaging. Treatment with Iva led to a HR reduction of 11.4 bpm (Iva 58.8±8.2 bpm vs placebo 70.2±8.3 bpm, p<0.0001).There was no difference in LVEF (%) (Iva 57.4±11.2 vs placebo 53.0±10.9, p=0.18), EDVi or ESVi. SVi (ml/m2) remained comparatively unchanged after long-term treatment with Iva (Iva 40.6±9.6 vs placebo 35.7±8.8, p=0.08). VTC parameters reflecting systolic LV function (PER, PET) were unaffected by Iva, while both PFR and PFR/EDV were significantly increased (PFR/EDV (s-1) Iva 2.4±0.4 vs placebo 2.1±0.4, p=0.03). There was a trend to longer PFT during treatment with Iva, though not reaching statistical significance. Medium and maximum aortic flow were not affected by treatment with Iva, while mean velocity (cm/s) was significantly reduced (Iva 6.7±2.7 vs placebo 9.0±3.4, p=0.01). Aortic flow parameters were correlated to aortic distensibility (AD), as surrogate parameter for arterial stiffness. AD was significantly correlated to both aortic flow and flow velocity, whereby mean velocity showed the strongest correlation to AD (r=0.74 [0.61 to 0.83], p<0.0001). Conclusion Systolic LV function was unaffected by treatment with Iva, while the filling during diastole was significantly improved. While medium and maximum aortic flow were not affected by Iva, mean velocity was significantly reduced. Aortic distensibility as surrogate parameter for arterial stiffness was significantly correlated to aortic mean velocity. This study confirms the underlying physiological principle of the If-current inhibitor Ivabradine. Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): This work was supported by the Deutsche Herzstiftung (German Heart Foundation) (F/14/11 to F.C.) and the Deutsche Forschungsgemeinschaft (DFG KFO 196 to U.L., S.H.S and M.B. and SFB TTR 219, S-01 to M.B.). The Saarland University Medical Center has received an unrestricted grant from Servier (France).

Probing the hidden atomic gas in Class I jets with SOFIA

Context. We present SOFIA/FIFI-LS observations of five prototypical, low-mass Class I outflows (HH111, SVS13, HH26, HH34, HH30) in the far-infrared [O I]63μm and [O I]145μm transitions. Aims. Spectroscopic [O I]63μm,145μm maps enable us to study the spatial extent of warm, low-excitation atomic gas within outflows driven by Class I protostars. These [O I] maps may potentially allow us to measure the mass-loss rates (Ṁjet) of this warm component of the atomic jet. Methods. A fundamental tracer of warm (i.e. T ~ 500–1500 K), low-excitation atomic gas is the [O I]63μm emission line, which is predicted to be the main coolant of dense dissociative J-type shocks caused by decelerated wind or jet shocks associated with protostellar outflows. Under these conditions, the [O I]63μm line can be directly connected to the instantaneous mass ejection rate. Thus, by utilising spectroscopic [O I]63μm maps, we wish to determine the atomic mass flux rate Ṁjet ejected from our target outflows. Results. Strong [O I]63μm emission is detected at the driving sources HH111IRS, HH34IRS, SVS13, as well as at the bow shock region, HH7. The detection of the [O I]63μm line at HH26A and HH8/HH10 can be attributed to jet deflection regions. The far-infrared counterpart of the optical jet is detected in [O I]63μm only for HH111, but not for HH34. We interpret the [O I]63μm emission at HH111IRS, HH34IRS, and SVS13 to be coming primarily from a decelerated wind shock, whereas multiple internal shocks within the HH111 jet may cause most of the [O I]63μm emission seen there. At HH30, no [O I]63μm,145μm was detected. The [O I]145μm line detection is at noise level almost everywhere in our obtained maps. The observed outflow rates of our Class I sample are to the order of Ṁjet ~ 10−6M⊙ yr−1, if proper shock conditions prevail. Independent calculations connecting the [O I]63μm line luminosity and observable jet parameters with the mass -loss rate are consistent with the applied shock model and lead to similar mass-loss rates. We discuss applicability and caveats of both methods. Conclusions. High-quality spectroscopic [O I]63μm maps of protostellar outflows at the jet driving source potentially allow a clear determination of the mass ejection rate.

Nobeyama 45 m mapping observations toward Orion A. I. Molecular outflows

We conducted an exploration of ${}^{12}$CO molecular outflows in the Orion A giant molecular cloud to investigate outflow feedback using ${}^{12}$CO ($J = 1\!-\!0$) and ${}^{13}$CO ($J = 1\!-\!0$) data obtained by the Nobeyama 45 m telescope. In the region excluding the center of OMC 1, we identified 44 ${}^{12}$CO (including 17 newly detected) outflows based on the unbiased and systematic procedure of automatically determining the velocity range of the outflows and separating the cloud and outflow components. The optical depth of the ${}^{12}$CO emission in the detected outflows is estimated to be approximately 5. The total momentum and energy of the outflows, corrected for optical depth, are estimated to be $1.6 \times 10^{2}\, M_{\odot }\:$km$\:$s$^{-1}$ and $1.5\times 10^{46}\:$erg, respectively. The momentum and energy ejection rate of the outflows are estimated to be 36% and 235% of the momentum and energy dissipation rates of the cloud turbulence, respectively. Furthermore, the ejection rates of the outflows are comparable to those of the expanding molecular shells estimated by Feddersen et al. (2018, ApJ, 862, 121). Cloud turbulence cannot be sustained by the outflows and shells unless the energy conversion efficiency is as high as 20%.

Differently sized cuckoos pose different threats to hosts

Hole-nesting tits Parus spp. have been classified as “unsuitable” hosts for cuckoo parasitism because cuckoos cannot enter a cavity if the entrance is too small. However, Chinese tits could reject alien eggs and egg ejection rate increased with the local diversity of parasitic cuckoo species. Antiparasitic behavior among Chinese tits may have evolved due to greater size variation among sympatric cuckoo species. This raises the question of whether differently sized parasitic cuckoos pose different threats to Chinese tits. A green-backed tit Parus monticolus population that is sympatric with Asian emerald cuckoo Chrysococcyx maculatus (eme-cuckoo, small-sized parasite) and common cuckoo Cuculus canorus (com-cuckoo, large-sized parasite), and a cinereous tit P. cinereus population that is only sympatric with com-cuckoo were chosen as study organisms. We observed behavioral response and recorded alarm calls of the 2 tit species to eme-cuckoo, com-cuckoo, chipmunk Tamias sibiricus (a nest predator) and dove Streptopelia orientalis (a harmless control), and subsequently played back alarm calls to conspecific incubating females. In dummy experiments, both tit species performed intense response behavior to chipmunk, but rarely responded strongly to the 3 avian species. In playback experiments, both tit species responded strongly to conspecific chipmunk alarm calls, but rarely responded to dove alarm calls. The intensity of response of incubating female green-backed tits to eme-cuckoo and com-cuckoo alarm calls were similar to that of chipmunk alarm calls, while the intensity to eme-cuckoo alarm calls was higher than the intensity to dove alarm calls which was similar to that of com-cuckoo alarm calls. In contrast, few female cinereous tits responded to eme-cuckoo and com-cuckoo alarm calls. These findings indicated that the threat level of eme-cuckoo was slightly greater than that of com-cuckoo for sympatric green-backed tits, but not for allopatric cinereous tits.

P2477Assessment of intraventricular flow dynamics in acute heart failure studied by Vector Flow Mapping

Background Although left ventricular (LV) flow dynamics should be closely related to LV morphology and function, little is known about how heart failure (HF) changes it. Pathline Analysis (PA), a recently developed software based on Vector Flow Mapping (VFM, Hitachi), enables us to trace the virtual blood particles entering to the LV in diastole and being ejected in systole. We investigated the change of flow dynamics in HF induced in dogs using PA. Methods In 15 open-chest dogs, HF was induced by intracoronary injection of microspheres. Color Doppler images of apical long-axis view were acquired using Prosound F75 (Hitachi) before and after HF and were analyzed by PA. We calculated the ratio of the numbers of entering particles in diastole and ejected particles in systole (ejection rate) and the distance reached by the particles in diastole corrected by the LV long-axis diameter (propagation distance). Apical and basal short axis images were acquired using GE Vivid E9 and were analyzed for peak rotation and peak twist. Results After inducing HF, LV end-diastolic pressure increased from 6±2 to 15±5 mmHg (p<0.001) and ejection fraction (EF), apical peak rotation and peak twist decreased significantly (EF; 58±5 to 36±8%, apical peak rotation; 14±5 to 3±2 degree, peak twist; 19±5 to 6±3 degree, p<0.05, respectively). PA showed most of the entering particles to the LV were ejected in the following systole at the control stage, but in HF, a significant part of the entering particles were not ejected and remained in the LV (Figure). Ejection rate decreased from 50±11 to 26±11% (p<0.001) and the propagation distance decreased from 85±9 to 66±13% (p<0.001) after inducing HF. There were significant relationships between indices obtained by PA and EF and peak twist (Table). Conclusion A significant part of inflow is not ejected directly to the outflow in the next systole and remains in the LV in HF, suggesting inefficient flow dynamics.

A Randomized, Double-Blind, Placebo-Controlled Parallel Study Demonstrating the Efficacy of A-F Betafood® on Gallbladder Function (P06-125-19)

Objectives To evaluate the efficacy of A-F Betafood® on gallbladder and liver function in healthy overweight adults. Methods A multi-center, randomized, double-blind, placebo-controlled parallel study was conducted on 50 healthy male and female adults 41–69 years of age, BMI 23.5–32.1 kg/m2 experiencing gastrointestinal distress when consuming fatty foods. Participants were randomized into two interventions: A-F Betafood® or placebo and consumed 2 tablets of the products with a meal, 3 times daily for 12 weeks. At baseline and week 12, liver function tests were performed as well as an ultrasound following a fat rich liquid meal to determine gallbladder volume, wall thickness, ejection fraction and ejection rate. Safety measurements included adverse events, vital signs, anthropometric measures, hematology and clinical chemistry. Results Forty-two subjects completed the study. There was a significant 9% (p = 0.049) decrease in gallbladder wall thickness in participants supplemented with A-F Betafood® while those on placebo showed a 6% increase. Significant within-group reductions of 32% (p = 0.044) in gallbladder volume 30 minutes post-meal and a significant increase of 19% (p = 0.047) in ejection fraction were observed in participants in the A-F Betafood® group but not in the placebo group following the 12-week supplementation. Gallbladder ejection rate showed non-significant 15% increase in participants supplemented with A-F Betafood® while those on placebo showed an 8% decrease. Gallbladder volume, emptying and ejection fraction were not significantly different between A-F Betafood® and placebo. There were no clinically relevant adverse events and safety parameters remained within normal clinical ranges. Conclusions Healthy participants, experiencing gastrointestinal distress when consuming fatty foods, showed clinically relevant improvements in gallbladder motility and gallbladder wall thickness without experiencing any adverse events when supplemented with A-F Betafood® for 12 weeks. Significant within group reductions in gallbladder volume and increases in ejection fraction, and non-significant increases in ejection rate are indicative of improvements in gallbladder motility suggesting a role for A-F Betafood® in populations at risk for gallbladder malfunction. Funding Sources Standard Process Inc., Palmyra, WI.

Influence of Trailing Edge Coolant Ejection Rate and Cut-Back Length on Energy Loss and Shockwave Intensity of a Transonic Turbine Blade

As part of our efforts to understand better ways and means to further improve jet engine performance, the influence of trailing edge coolant ejection rate and cut-back length on energy loss and shockwave intensity of a transonic turbine blade is numerically investigated with an exit Mach number of 1.2 for different coolant/main stream mass-flux ratios and cut-back lengths. Test results indicate both coolant ejection rate and cutback length have their optimum values, and the best ejection rate and the best cut-back length correlate with each other. From the view of minimizing the energy loss coefficient, the best ejection rate decreases with the increasing cut-back length. And from the view of minimizing the trailing edge shockwave intensity, a higher trailing edge coolant ejection rate and a longer trailing edge cut-back can reduce the shockwave intensity. It is therefore believed that these findings can of course facilitate the design of a trailing edge cooling system for transonic turbine blade to further improve jet engine performance. Moreover, trailing edge coolant ejection can be considered as an active flow control method at the same time.