Slow Deflation Research Articles

EFFECTIVENESS OF UTERINE BALLOON TAMPONADE IN MANAGEMENT OF PRIMARY POSTPARTUM HEMORRHAGE

Objectives: To determine the effectiveness of uterine balloon tamponade in the management of primary post partum hemorrhage.Materials and Methods: This cross sectional descriptive study was conducted in Tehsil Headquarter Hospital Swabi from 1st May 2023 to 31st October 2023. A total of 177 women presenting with primary PPH regardless of parity were included in the study. All were treated with standard protocols for PPH treatment .The balloon was removed 12 hours after its insertion to determine the effectiveness in terms of less than 100 ml loss of blood. Slow deflation of balloon tamponade with simultaneous monitoring for resumption of bleeding.Results: Mean age of the patients were 28.497±2.43 years, gravidity 2.638±1.19, parity 1.638±1.19, gestational age 38.689±1.12 and mean BMI was 26.1±1.35 Kg/m2. Uterine atony was the cause of PPH in 78.6%. Those who underwent normal vaginal delivery were 66.1% while 33.9% underwent C-section. Out of the total 177 cases, uterine balloon tamponade was effective in 129 cases (72.9%) with a statistically significant diff erence of 0.001 in combine spontaneous or induced labor.Conclusion: The intended study concludes that balloon tamponade is a successful and reliable approach in addressing PPH. This method effectively aids in controlling excessive bleeding following delivery, highlighting its significance as an effective treatment option in managing PPH.

Arylene Diimide Derivatives as Anolyte Materials with Two-Electron Storage for Ultrastable Neutral Aqueous Organic Redox Flow Batteries

Arylene Diimide Derivatives as Anolyte Materials with Two-Electron Storage for Ultrastable Neutral Aqueous Organic Redox Flow Batteries

Waveform inversion of the ultra-long-period seismic event associated with ground tilt motion during an eruption of Mount Kusatsu–Shirane, Japan, on January 23, 2018

We conducted waveform inversions of an ultra-long-period (~ 240-s) event associated with the phreatic eruption of Mount Kusatsu–Shirane on January 23, 2018. We used broadband seismic and tilt records from three stations surrounding the eruption site. The horizontal components of the broadband seismic records were severely contaminated by tilt motions. We applied a waveform inversion algorithm to account for both the translational and tilt motions. To reduce the number of free parameters, we assumed a tensile crack source and conducted grid searches for the centroid location and orientation of the crack. The results showed a rapid inflation of 105 m3 of the crack, followed by a slow deflation starting 8–11 s prior to the onset of the eruption. The source location and crack orientation were not uniquely determined. The most likely source is a north–south-opening sub-vertical crack near the eruptive craters. This ultra-long-period event may represent volcanic fluid migration from depth to the surface through a vertical crack during the eruption.Graphical abstract

Influence of the speed of deflation of the stent delivery system in the myocardial blush and ST-segment resolution in primary angioplasty: a randomized study

Abstract Introduction Distal embolization may compromise the results of primary angioplasty. Our aim is to analyze the influence of the speed of deflation of the stent delivery system on the myocardial blush ≥2 and on the ST-Segment resolution ≥70%. Methods From December 2016 to February 2019, all consecutive patients with ST-elevation myocardial infarction who underwent urgent coronary angiography at our institution who were susceptible of thrombectomy, IIB-IIIA inhibitors and direct stenting were randomized 1:1 to fast deflation of the stent delivery system (group 1, n=103) or to slow deflation at 1 atm/second (group 2, n=107). Pre- and postdilatation was not allowed per protocol. The primary outcomes were the myocardial blush ≥2 and the ST-Segment resolution ≥70% while the size of myocardial damage, ejection fraction at discharge and at 12 months and total and cardiovascular mortality at 12 months were the secondary outcomes. A multivariate analysis was performed to analyze the influence of the speed of deflation of the stent delivery system in both primary end-points in case of possible imbalances among groups despite the randomization. Results Both groups represented 47% of the 447 procedures of primary angioplasty performed in that period. Baseline characteristics of the whole cohort: female gender 46 (21.9%), age 59.5±10.6 years, diabetes 35 (16.7%), Killip class IV 5 (2.4%), total ischemic time 177.5 (124–275) minutes and door to balloon time 84 (66–120.5) minutes. There were not differences in clinical or angiographic characteristics between both groups, although there was a non-significant trend towards larger reference vessel diameter in the slow deflation group (2.74±0.42 vs. 2.86±0.47, p=0.07). The study was prematurely stopped with 50% of the calculated sample size due to futility. The primary endpoint of myocardial blush ≥2 occurred in 77 (74.7%) vs. 79 (75.2%), p=0.93 and ST-Segment resolution ≥70% in 54 (53.9%) vs. 59 (55.5%), p=0.75 in group 1 and 2, respectively, without differences in any of the secondary endpoints. The speed of deflation of the stent delivery system did not show any influence on the MB or ST-Segment resolution ≥70% in the multivariate analysis. Predictors of myocardial blush ≥2 were systolic blood pressure at admission, creatinine clearance <60 ml/min and maximal diameter postprocedure. Diabetes, previous infarction, left anterior descending, TIMI ≥2 before intervention, TIMI 3 after intervention and collateral supply grade ≥2 were predictors of ST segment resolution≥70% with an area under the curve of 0.71 (0.63–0.80) and 0.75 (0.68–0.82), respectively. Conclusions In our series, the speed of deflation of the stent delivery system in primary angioplasty did not modified the myocardial blush ≥2 or ST-Segment resolution ≥70% and neither showed any influence in clinical outcomes, size of myocardial infarction by biomarkers and ejection fraction. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Abbott Laboratories

Balloon Deflation Strategy during Primary Percutaneous Coronary Intervention in Acute ST-Segment Elevation Myocardial Infarction: A Randomized Controlled Clinical Trial and Numerical Simulation-Based Analysis.

Background Primary percutaneous coronary intervention (PCI) is the best available reperfusion strategy in patients with acute ST-segment elevation myocardial infarction (STEMI). However, PCI is associated with a serious problem known as no-reflow phenomenon, resulting in poor clinical and functional outcomes. This study aimed to compare the influences of different balloon deflation velocity on coronary flow and cardiovascular events during primary PCI in STEM as well as transient hemodynamic changes in in vitro experiments. Method and Results. 211 STEMI patients were randomly assigned to either a rapid or a slow balloon deflation group during stent deployment. The primary end point was coronary flow at the end of PCI procedure, and secondary end points included myocardial infarct size. Transient hemodynamic changes were evaluated through an in vitro experimental apparatus and a computer model. In clinical practice, the level of corrected TIMI frame count (cTFC) in slow balloon deflation after primary PCI was significantly lower than that of rapid balloon deflation, which was associated with smaller infarct size. Numerical simulations revealed that the rapid deflation led to a sharp acceleration of flow in the balloon-vessel gap and a concomitant abnormal rise in wall shear stress (WSS). Conclusion This randomized study demonstrated that the slow balloon deflation during stent implantation improved coronary flow and reduced infarct size in reperfused STEMI. The change of flow in the balloon-vessel gap and WSS resulted from different balloon deflation velocity might be partly accounted for this results.

03:36 PM Abstract No. 67 Expedited TR Band removal after transradial visceral interventions: a single-center experience

The current hemostasis protocol provided by Terumo radial (TR) band (Terumo, Sommerset, NJ) manufacturer and cited by current interventional radiology literature for visceral interventions is non occlusive patent hemostasis achieved by inflation of TR band for 60-90 minutes, with subsequent slow deflation until eventual removal. We aimed to determine if the average time to TR Band removal can be reduced without adverse effects. Transradial non-coronary visceral interventions performed between July 2017 and August 2018 were retrospectively reviewed. Following TR band application, the nursing staff was instructed to start TR band deflation process at 30-60 minutes. If bleeding was noted, 1 cc of air was reinflated and deflation was resumed in 30 minutes. Data collected included demographics, procedure details, nursing notes for TR band removal, and complications. 37 patients (26 Men, 17 Female, Mean age 46.4 years) underwent 47 transradial interventions with post operative TR band placement. Procedures included 11 Uterine Fibroid Embolization, 19 Y90 MAA and treatment, 12 chemoembolization and 5 other. All patients received an intra-arterial cocktail of 2.5 mg verapamil, 3000 units heparin and 200 mcg of nitroglycerin. All procedures were performed with a 5F glide slender sheath(Terumo, Sommerset, NJ). Median procedure time was 56.64 minutes (range 30- 100 mins). 43/47 ( 91.5%) patients had no access site bleeding after initial band deflation (mean time of removal: 53.1 mins, standard deviation: 14.3 mins). 4/47 (8.5%) patients had bleeding during initial band deflation, and were re-inflated as per protocol aforementioned. Mean time to successful removal in these patients was 77.5 minutes (±25.3 minutes). There were no access site bleeding complications in the immediate postoperative period or clinic follow up. 1 patient had asymptomatic radial artery thrombosis at 2 week follow up. Expedited removal of TR band at 30-60 minutes may be safe for non occlusive hemostasis following transradial visceral interventions. Future prospective studies with larger patient cohorts would be helpful.

From debulking to delivery: sequential use of rotational atherectomy and Guidezilla\u2122 for complex saphenous vein grafts intervention

BackgroundPercutaneous coronary interventions (PCI) of old calcified saphenous vein grafts (SVGs) is challenging and is associated with a considerably high risk of adverse ischemic events in the short- and long-term as compared to native coronary arteries. We report a case in which a non-dilatable, calcified SVG lesion is successfully treated with rotational atherectomy followed by PCI and stenting with local stent delivery (LSD) technique using the Guidezilla™ guide extension catheter (5-in-6 Fr) in the “child-in-mother” fashion.Case presentationA 70 years-old man with a dilated ischemic cardiomyopathy, triple coronary artery bypass grafting (CABG) in 1990 and chronic renal failure (baseline GFR: 45 ml/min/1.73 m2) underwent a coronary angiography for a Non-ST segment elevation myocardial infarction (NSTEMI). Native coronary circulation was completely occluded at the proximal segments. Grafts angiography showed a tandem calcified lesions of SVG on distal right coronary artery (RCA) and an ostial stenosis of the SVG on first obtuse marginal branch (OM1). Left internal mammary artery on the mid left anterior descending artery was patent. Ad Hoc PCI of SVG on RCA was attempted. The proximal calcified stenosis has been crossed with a 1.5 x 12 mm balloon only with the support of Guidezilla™, however the non-compliant (NC) balloon 2.5 x 15 mm was unable to break the hard and calcified plaque. After several attempts, the procedure was interrupted with a suboptimal result. An elective transradial PCI of SVG on RCA with rotational atherectomy was performed. Two runs with 1.25 mm burr and 2 runs with 1.5 mm burr were carried out. Then, the use of distal anchoring balloon warranted support and tracking, made as centring rail for the advance of the tip of the “mother-and-child” catheter into the SVG. During slow deflation of the balloon, the Guidezilla™ was advanced distal to the stenoses to be stented, thus allowing the placement of two long drug eluting stents according to a LSD technique.ConclusionsRotational atherectomy is a feasible option for non-dilatable stenoses in old SVGs when there is no evidence of thrombus or vessel dissection and the subsequent use of “mother-and-child” catheter has a key role, especially in case of radial approach, for long stents delivery.

Airway occlusion assessed by single breath N2 test and lung P-V curve in healthy subjects and COPD patients

PurposeTo determine whether the analysis of the slow expiratory transpulmonary pressure–volume (PL-V) curve provides an alternative to the single-breath nitrogen test (SBN) for the assessment of the closing volume (CV). MethodsSBN test and slow deflation PL-V curve were simultaneously recorded in 40 healthy subjects and 43 COPD patients. Onset of phase IV identified CV in SBN test (CVSBN), whereas in the PL-V curve CV was identified by: a) deviation from the exponential fit (CVexp), and b) inflection point of the interpolating sigmoid function (CVsig). ResultsIn the absence of phase IV, COPD patients exhibited a clearly discernible inflection in the PL-V curve. In the presence of phase IV, CVSBN and CVexp coincided (CVSBN/CVexp=1.04±0.04 SD), whereas CVsig was systematically larger (CVsig/CVexp=2.1±0.86). ConclusionThe coincidence between CVSBN and CVexp, and the presence of the inflection in the absence of phase IV indicate that the deviation of the PL-V curve from the exponential fit reliably assesses CV.

Characterization of open and closed volcanic systems in Indonesia and Mexico using InSAR time series

AbstractWe use 2007–2011 Advanced Land Observing Satellite (ALOS) data to perform an arc‐wide interferometric synthetic aperture radar (InSAR) time series survey of the Trans‐Mexican Volcanic Belt (TMVB) and to study time‐dependent ground deformation of four Indonesian volcanoes selected following the 2007–2009 study of Chaussard and Amelung (2012). Our objectives are to examine whether arc volcanoes exhibit long‐term edifice‐wide cyclic deformation patterns that can be used to characterize open and closed volcanic systems and to better constrain in which cases precursory inflation is expected. We reveal deformation cycles at both regularly active and previously inactive Indonesian volcanoes, but we do not detect deformation in the TMVB, reflecting a lower activity level. We identify three types of relationships between deformation and activity: inflation prior to eruption and associated with or followed by deflation (Kerinci and Sinabung), inflation without eruption and followed by slow deflation (Agung), and eruption without precursory deformation (Merapi, Colima, and Popocatépetl; at Merapi, no significant deformation is detected even during eruption). The first two cases correspond to closed volcanic systems and suggest that the traditional model of magmatic systems and eruptive cycles do apply to andesitic volcanoes (i.e., inflation and deflation episodes associated with magma accumulation or volatile exsolution in a crustal reservoir followed by eruptions or in situ cooling). In contrast, the last case corresponds to open volcanic systems where no significant pressurization of the magmatic reservoirs is taking place prior to eruptions and thus no long‐term edifice‐wide ground deformation can be detected. We discuss these results in terms of InSAR's potential for forecasting volcanic unrest.

Near real‐time monitoring of volcanic surface deformation from GPS measurements at Long Valley Caldera, California

AbstractLong Valley Caldera in eastern California is an active volcanic area and has shown continued unrest in the last three decades. We have monitored surface deformation from Global Positioning System (GPS) data by using a projection method that we call Targeted Projection Operator (TPO). TPO projects residual time series with secular rates and periodic terms removed onto a predefined spatial pattern. We used the 2009–2010 slow deflation as a target spatial pattern. The resulting TPO time series shows a detailed deformation history including the 2007–2009 inflation, the 2009–2010 deflation, and a recent inflation that started in late‐2011 and is continuing at the present time (November 2012). The recent inflation event is about four times faster than the previous 2007–2009 event. A Mogi source of the recent event is located beneath the resurgent dome at about 6.6 km depth at a rate of 0.009 km3/yr volume change. TPO is simple and fast and can provide a near real‐time continuous monitoring tool without directly looking at all the data from many GPS sites in this potentially eruptive volcanic system.

Japan as a Role Model?

Some analysts, noting Japan's continued slow deflation, assert that Japan is trapped in a slow-growth, deflationary equilibrium. Former Governor Shirakawa argued that Japan had "gotten out"—at least when judged by the growth of real GDP.

Constraints on time-dependent volcanic source models at Long Valley Caldera from 1996 to 2009 using InSAR and geodetic measurements

SUMMARY Continuous monitoring of Long Valley Caldera since the late 1970s, including data from seismic and geodetic networks has shown renewed episodic unrest with accelerated uplift separated by reduced uplift, no activity, or slow deflation. We examine the time-dependent behaviour at Long Valley Caldera from 1996 to 2009 by integrating InSAR and continuous GPS (CGPS) measurements. The ERS-1/2 radar data between 1996 and 2008 and reprocessed three-component CGPS data from the Long Valley GPS network from 1996 to 2009 were combined to invert for source geometry and volume change for the following deformation episodes: 1997–1998 uplift, 2002–2003 uplift, 2004–2007 slow subsidence, and 2007–2009 slow uplift. We employed non-linear Monte-Carlo random search approaches (random cost and simulated annealing) in our inversion and examined models including spherical and finite sources (dipping prolate spheroid). Our results show that the sources of all post-2000 events (i.e. 2002–2003, 2007–2009 uplift and 2004–2007 subsidence) locate at shallow depths of ∼6–8 km and have nearly identical surface locations, suggesting that these events may be caused by the same source in the mid-crust, possibly a mixture of hydrothermal and partial-melt magma. All three events, 2002–2003, 2004–2007, 2007–2009, are characterized by the low total volume change: ∼0.01, ∼–0.003, ∼0.006 km3, respectively, with corresponding volume change rates of ∼0.007, ∼–0.001, ∼0.002 km3 yr–1. The 1997–1998 inflationary event has a steeper source geometry and much greater volume change rate (∼0.03 km3 yr–1) than the other events, in agreement with previous studies. This suggests it is possibly driven by magma intrusion beneath the resurgent dome from a deeper source. If we regard post-2000 events as proxies for future eruption hazard, the inferred source dynamics (e.g. mid-crustal location and subdued volume change) and accompanied decrease in earthquake activity from these post-2000 events suggest that the probability for near-term eruption is low. Our study demonstrates that CGPS, along with InSAR, provide a valuable tool for monitoring time-dependent source processes at active volcanic regions.

How Important is the Recommended Slow Cuff Pressure Deflation Rate for Blood Pressure Measurement?

Cuff pressure deflation rate influences blood pressure (BP) measurement. However, there is little quantitative clinical evidence on its effect. Oscillometric pulses recorded from 75 subjects at the recommended deflation rate of 2-3 mmHg per second were analyzed. Some pulses were removed to realize six faster rates (2-7 times faster than the original). Systolic, diastolic, and mean arterial blood pressures (SBP, DBP, MAP) were determined from the original and six reconstructed oscillometric waveforms. Manual measurement was based on the appearance of oscillometric pulse peaks, and automatic measurement on two model envelopes (linear and polynomial) fitted to the sequence of oscillometric pulse amplitudes. The effects of deflation rate on BP determination and within-subject BP variability were analyzed. For SBP and DBP determined from the manual measurement, different deflation rates resulted in significant changes (both p < 0.001). However, for SBP, DBP, and MAP determined from the automatic linear and polynomial model techniques, there was no deflation rate effect (all p > 0.3). Faster deflation increased the within-subject BP variability (all p < 0.001). In conclusion, for the manual technique accurate BP measurement could be achieved only with the recommended slow deflation rate, and for the automatic model-based techniques, the deflation rate had little effect.

Mechanical model of the ultrafast underwater trap ofUtricularia

The underwater traps of the carnivorous plants of the Utricularia species catch their prey through the repetition of an "active slow deflation followed by passive fast suction" sequence. In this paper, we propose a mechanical model that describes both phases and strongly supports the hypothesis that the trap door acts as a flexible valve that buckles under the combined effects of pressure forces and the mechanical stimulation of trigger hairs, and not as a panel articulated on hinges. This model combines two different approaches, namely (i) the description of thin membranes as triangle meshes with strain and curvature energy, and (ii) the molecular dynamics approach, which consists of computing the time evolution of the position of each vertex of the mesh according to Langevin equations. The only free parameter in the expression of the elastic energy is the Young's modulus E of the membranes. The values for this parameter are unequivocally obtained by requiring that the trap model fires, like real traps, when the pressure difference between the outside and the inside of the trap reaches about 15 kPa. Among other results, our simulations show that, for a pressure difference slightly larger than the critical one, the door buckles, slides on the threshold, and finally swings wide open, in excellent agreement with the sequence observed in high-speed videos.

Microbubble characterization through acoustically induced deflation

Ultrasound contrast agents (UCA) populations are typically polydisperse and contain microbubbles with radii over a given range. Although the behavior of microbubbles of certain sizes might be masked by the behavior of others, the acoustic characterization of UCA is typically made on full populations. In this paper, we have combined acoustic and optical methods to investigate the response of isolated lipid-shelled microbubbles to low-pressure (49 and 62 kPa peak negative pressure) ultrasound tone bursts. These bursts induced slow deflation of the microbubbles. The experimental setup included a microscope connected to a fast camera acquiring one frame per pulse transmitted by a single-element transducer. The behavior of each bubble was measured at multiple frequencies, by cyclically changing the transmission frequency over the range of 2 to 4 MHz during subsequent pulse repetition intervals. The bubble echoes were captured by a second transducer and coherently recorded. More than 50 individual microbubbles were observed. Microbubbles with radii larger than 3 mum did not experience any size reduction. Smaller bubbles slowly deflated, generally until the radius reached a value around 1.4 microm, independent of the initial microbubble size. The detected pressure amplitude backscattered at 2.5 cm distance was very low, decreasing from about 5 Pa down to 1 Pa at 2 MHz as the bubbles deflated. The resonant radius was evaluated from the echo amplitude normalized with respect to the geometrical cross section. At 2-MHz excitation, deflating microbubbles showed highest normalized echo when the radius was 2.2 microm while at higher excitation frequencies, the resonant radius was lower. The relative phase shift of the echo during the deflation process was also measured. It was found to exceed pi/2 in all cases. A heuristic procedure based on the analysis of multiple bubbles of a same population was used to estimate the undamped natural frequency. It was found that a microbubble of 1.7 microm has an undamped natural frequency of 2 MHz. The difference between this size and the resonant radius is discussed as indicative of significant damping.

Slow deflation of a tracheal tube cuff: an unusual cause

Acta Anaesthesiologica ScandinavicaVolume 50, Issue 4 p. 519-519 Slow deflation of a tracheal tube cuff: an unusual cause N. Malhotra, Corresponding Author N. Malhotra * Dr Naveen Malhotra 128/19, Naveen Niketan Civil Hospital Road Rohtak-124001 Haryana India e-mail: [email protected]Search for more papers by this authorS. Singhal, S. SinghalSearch for more papers by this author N. Malhotra, Corresponding Author N. Malhotra * Dr Naveen Malhotra 128/19, Naveen Niketan Civil Hospital Road Rohtak-124001 Haryana India e-mail: [email protected]Search for more papers by this authorS. Singhal, S. SinghalSearch for more papers by this author First published: 17 March 2006 https://doi.org/10.1111/j.1399-6576.2005.00875.xCitations: 2Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume50, Issue4April 2006Pages 519-519 RelatedInformation

Time Poor: Rushing Decreases the Accuracy and Reliability of Blood Pressure Measurement Technique in Pregnancy

Background: In pregnancy, absolute blood pressure (BP) limits define preeclampsia. Therefore, BP in pregnancy should be measured accurately and in accordance with accepted guidelines. Accuracy of BP readings determined by rate of cuff deflation was analyzed. This study also investigated the compliance of clinical staff at Royal Prince Alfred Hospital, Australia, to guidelines for BP measurement. Methods: The study was an observational trial of 98 normotensive antenatal or recently postnatal patients. Two BP readings were taken, each with fast (>5 mm Hg/sec) and slow (≤2 mm Hg/sec) descent of mercury and compared by Bland-Altman analysis. Also, BP techniques used by junior doctors, specialist obstetricians, and midwives were compared using a 9-point scale. Findings: Australian national guidelines recommend slow descent of mercury. Fast descent underestimated the systolic BP by 9 mm Hg (95% confidence interval [CI], −23 to +5 mm Hg) (p < 0.001). Fast descent measured the diastolic BP within 2 mm Hg (95% CI, −10 to +14 mm Hg) (not different, p = 0.151). Accuracy of fast cuff deflation was 28% for systolic BP and 50% for diastolic BP for <5 mm Hg, and respectively, 64% and 68% for <10 mm Hg, 84% and 80% for <15 mm Hg and 91% and 87% for <20 mm Hg. Compliance with guidelines was greatest for specialists and midwives (p = 0.001) and their most commonly missed feature (76% to100%) was slow cuff deflation. Interpretation: Rapid cuff deflation underestimates the systolic BP compared to accepted guidelines (≤2 mm Hg/sec). Medical and midwifery staff may not follow accepted guidelines for BP measurement, particularly with regard to rate of cuff deflation. Potential misdiagnosis and under-treatment of patients with hypertension may compromise pregnancy outcomes.

Waveform inversion of very long period impulsive signals associated with magmatic injection beneath Kilauea volcano, Hawaii

We use data from broadband seismometers deployed around the summit of Kilauea Volcano to quantify the mechanism associated with a transient in the flow of magma feeding the east rift eruption of the volcano. The transient is marked by rapid inflation of the Kilauea summit peaking at 22 μrad 4.5 hours after the event onset, followed by slow deflation over a period of 3 days. Superimposed on the summit inflation is a series of sawtooth displacement pulses, each characterized by a sudden drop in amplitude lasting 5–10 s followed by an exponential recovery lasting 1–3 min. The sawtooth waveforms display almost identical shapes, suggesting a process involving the repeated activation of a fixed source. The particle motion associated with each sawtooth is almost linear, and its major swing shows compressional motion at all stations. Analyses of semblance and particle motion are consistent with a point source located 1 km beneath the northeast edge of the Halemaumau pit crater. To estimate the source mechanism, we apply a moment tensor inversion to the waveform data, assuming a point source embedded in a homogeneous half‐space with compressional and shear wave velocities representative of the average medium properties at shallow depth under Kilauea. Synthetic waveforms are constructed by a superposition of impulse responses for six moment tensor components and three single force components. The origin times of individual impulses are distributed along the time axis at appropriately small, equal intervals, and their amplitudes are determined by least squares. In this inversion, the source time functions of the six tensor and three force components are determined simultaneously. We confirm the accuracy of the inversion method through a series of numerical tests. The results from the inversion show that the waveform data are well explained by a pulsating transport mechanism operating on a subhorizontal crack linking the summit reservoir to the east rift of Kilauea. The crack acts like a buffer in which a batch of fluid (magma and/or gas) accumulates over a period of 1–3 min before being rapidly injected into a larger reservoir (possibly the east rift) over a timescale of 5–10 s. The seismic moment and volume change associated with a typical batch of fluid are approximately 1014 N m and 3000 m3, respectively. Our results also point to the existence of a single force component with amplitude of 109 N, which may be explained as the drag force generated by the flow of viscous magma through a narrow constriction in the flow path. The total volume of magma associated with the 4.5‐hour‐long activation of the pulsating source is roughly 500,000 m3 in good agreement with the integrated volume flow rate of magma estimated near the eruptive site.

Pulmonary Function Alterations in F344 Rats Following Chronic Ozone Inhalation

AbstractThe impact of a 20-mo exposure to ozone on the pulmonary function of rats was assessed by performing a single series of measurements after exposures were completed. Four to 10 male and female F344 rats per group were exposed 6 h/day, 5 days/wk for 20 mo to ozone at 0.12, 0.5, or 1.0 ppm, or to clean air as controls. One to 3 days after the last exposure, the rats were anesthetized using halothane, fitted with oral endotracheal and esophageal catheters, and measured using plethysmographic techniques. The significances of differences between mean values for control and treated rats were tested by multiple comparisons. The values and intersubject variability for over 30 measured and calculated parameters were similar to those reported previously for similarly aged rats. The only consistent exposure-related effect was a small reduction of residual volume measured during slow lung deflation. This trend was observed in most exposed groups, but was most significant in females at the 0.5 ppm level. Fibros...

Does the speed of balloon deflation affect the complication rate of coronary angioplasty?

Two hundred consecutive coronary arteries in 157 patients undergoing angioplasty were randomized to fast or slow balloon deflation. Angioplasty was successful in 188 cases (101 with slow and 87 with fast deflation). There was no significant difference between the 2 groups with regard to the total number of dissections, although there was a greater number in the slow deflation group, and no difference in the number of minor dissections (National Heart, Lung, and Blood Institute types A and B). There was a significantly greater number of more severe dissections (types C to F) in the slow deflation group (20 vs 5; p = 0.013). It is proposed that the greater number of severe dissections is due to either increased turbulence or movement of the partially deflated balloon during slow deflation. Thus, slow balloon deflation during coronary angioplasty is associated with a higher complication rate than is conventional rapid deflation.