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This study uses infrasound detections from a repetitive source to estimate the effect of the atmosphere's temporal variability on infrasound. While a previous paper focused on infrasound propagation through the troposphere to a distance of 54 km, this study uses stratospheric returns detected 256 km from the source. Based on source‐receiver pairs, the empirical Green's function is calculated every 20 s for 52 events; these allow generating a set of synthetic signals where variations are ascribed to variation in the atmosphere. In addition, observations are compared with numerical simulation results based on realistic atmospheric conditions. Results show that variations of stratospheric infrasound signals are observed over timescales ranging from tens of seconds to minutes and have dominant periods ranging from tens to hundreds of seconds. These results motivate using infrasound to probe short temporal changes in the middle atmosphere and study their underlying phenomena. Key Points: Evidence for temporal (minute‐scale) variability of the middle atmosphere is observed by infrasoundShort temporal dynamics affects infrasonic phases, waveforms, propagation time, and energyThe same atmospheric phenomena drive variations of infrasonic correlation coefficient and energy [ABSTRACT FROM AUTHOR]

Global seismographic networks (GSNs) emerged during the late nineteenth and early twentieth centuries, facilitated by seminal international developments in theory, technology, instrumentation, and data exchange. The mid‐ to late‐twentieth century saw the creation of the World‐Wide Standardized Seismographic Network (1961) and International Deployment of Accelerometers (1976), which advanced global geographic coverage as seismometer bandwidth increased greatly allowing for the recording of the Earth's principal seismic spectrum. The modern era of global observations and rapid data access began during the 1980s, and notably included the inception of the GEOSCOPE initiative (1982) and GSN (1988). Through continual improvements, GEOSCOPE and the GSN have realized near‐real time recording of ground motion with state‐of‐art data quality, dynamic range, and timing precision to encompass 180 seismic stations, many in very remote locations. Data from GSNs are increasingly integrated with other geophysical data (e.g., space geodesy, infrasound and Interferometric Synthetic Aperture Radar). Globally distributed seismic data are critical to resolving crust, mantle, and core structure; illuminating features of the plate tectonic and mantle convection system; rapid characterization of earthquakes; identification of potential tsunamis; global nuclear test verification; and provide sensitive proxies for environmental changes. As the global geosciences community continues to advance our understanding of Earth structure and processes controlling elastic wave propagation, GSN infrastructure offers a springboard to realize increasingly multi‐instrument geophysical observatories. Here, we review the historical, scientific, and monitoring heritage of GSNs, summarize key discoveries, and discuss future associated opportunities for Earth Science. Plain Language Summary: Global seismographic networks (GSNs) record information‐rich ground motion signals that allow scientists and nations to identify and quantify global earthquakes and other seismic sources, and to rapidly assess their significance and impacts on society. In addition to providing a global standard for the monitoring and assessment of such events, these networks provide unique high‐quality data that are fundamental to revealing Earth's structure and dynamic behavior. Scientific applications of GSNs, supplemented by regional data, include imaging the deep interior of the Earth and its plate tectonic system, modeling the structure and dynamics of the inner core, imaging and understanding the rupture of earthquake faults, detecting, discriminating, and characterizing nuclear and other explosions, and improving our general understanding of Earth's ubiquitous seismic wavefield and the unique information that it conveys from the deep interior to the surface and atmosphere of the planet. Leveraging the extensive and hardened infrastructure at these global observatories facilitates the recording of other signals of geophysical interest, such as the magnetic field, low frequency sound waves, and meteorological observations. We review the heritage of GSNs, including their history and resulting scientific achievements, and summarize future opportunities for these networks to contribute further to improved advancements in Earth science. Key Points: Long running globally distributed seismographic networks are fundamental to understanding Earth's interior structure and processesNetworks have expanded beyond initial mid‐twentieth century design which were focused on recording signals from earthquakes and explosionsGlobal seismic data combined with data from nearby geophysical instrumentation continue to facilitate new discoveries in Earth science [ABSTRACT FROM AUTHOR]

Infrasound monitoring is used in the forensic analysis of events, studying the physical processes of sources of interest, and probing the atmosphere. The dynamical nature of the atmosphere and the use of infrasound as a forensic tool lead to the following questions; (1) what is the timescale of atmospheric variability that affects infrasonic signals? (2) how do infrasound signals vary as a function of time? This study addresses these questions by monitoring a repetitive infrasound source and its corresponding tropospheric returns 54 km away. Source‐receiver empirical Green's functions are obtained every 20 s and used to demonstrate the effect of atmospheric temporal variability on infrasound propagation. In addition, observations are compared to predicted simulated signals based on realistic atmospheric conditions. Based on 127 events over 3 days, it is shown that infrasound properties change within tens of seconds. Particularly, phases can appear and disappear, the propagation time varies, and the signals' energy fluctuates. Such variations are attributed to changes in temperatures and winds. Furthermore, atmospheric models can partly explain the observed changes. Therefore, this study highlights the potential of high temporal infrasound‐based atmospheric sounding. Key Points: Evidence for temporal (minute‐scale) variability of the lower troposphere is observed by infrasoundShort temporal dynamics affects infrasonic phases, waveforms, propagation time, and energy [ABSTRACT FROM AUTHOR]

In this review, we give a state-of-the-art account of uterine contractility, focussing on excitation-contraction (electro-mechanical) coupling ( ECC). This will show how electrophysiological data and intracellular calcium measurements can be related to more modern techniques such as confocal microscopy and molecular biology, to advance our understanding of mechanical output and its modulation in the smooth muscle of the uterus, the myometrium. This new knowledge and understanding, for example concerning the role of the sarcoplasmic reticulum ( SR), or stretch-activated K channels, when linked to biochemical and molecular pathways, provides a clearer and better informed basis for the development of new drugs and targets. These are urgently needed to combat dysfunctions in excitation-contraction coupling that are clinically challenging, such as preterm labour, slow to progress labours and post-partum haemorrhage. It remains the case that scientific progress still needs to be made in areas such as pacemaking and understanding interactions between the uterine environment and ion channel activity. [ABSTRACT FROM AUTHOR]

Oxytocin is a nonapeptide hormone that has a central role in the regulation of parturition and lactation. In this review, we address oxytocin receptor ( OTR) signalling and its role in the myometrium during pregnancy and in labour. The OTR belongs to the rhodopsin-type ( Class 1) of the G-protein coupled receptor superfamily and is regulated by changes in receptor expression, receptor desensitisation and local changes in oxytocin concentration. Receptor activation triggers a number of signalling events to stimulate contraction, primarily by elevating intracellular calcium ( Ca2+). This includes inositol-tris-phosphate-mediated store calcium release, store-operated Ca2+ entry and voltage-operated Ca2+ entry. We discuss each mechanism in turn and also discuss Ca2+-independent mechanisms such as Ca2+ sensitisation. Because oxytocin induces contraction in the myometrium, both the activation and the inhibition of its receptor have long been targets in the management of dysfunctional and preterm labours, respectively. We discuss current and novel OTR agonists and antagonists and their use and potential benefit in obstetric practice. In this regard, we highlight three clinical scenarios: dysfunctional labour, postpartum haemorrhage and preterm birth. [ABSTRACT FROM AUTHOR]

Please cite this paper as: Arrowsmith S, Wray S, Quenby S. Maternal obesity and labour complications following induction of labour in prolonged pregnancy. BJOG 2011;118:578-588. To investigate the effect of maternal obesity on mode of delivery following induction of labour (IOL) for prolonged pregnancy and subsequent intrapartum and neonatal complications. Retrospective (historical) cohort study. Liverpool Women's Hospital NHS Foundation Trust, UK. A total of 29 224 women with singleton pregnancies between 2004 and 2008 of whom 3076 had a prolonged pregnancy (defined as ≥290 days or 41 weeks of gestation) and received IOL. Kruskal-Wallis test, chi-square test and multivariable logistic regression. Mode of delivery and risk of delivery and neonatal complications in obese verses non-obese women following IOL. Obese women had a significantly higher rate of IOL ending in caesarean section compared with women of normal weight following IOL (38.7% versus 23.8% primiparous; 9.9% versus 7.9% multiparous women, respectively); however, length of labour, incidence of postpartum haemorrhage and third-degree tear, rate of low cord blood pH, low Apgar scores and shoulder dystocia were similar in all body mass index categories. Complications included a higher incidence of fetal macrosomia and second-degree, but not third-degree, tear in primiparous women. Higher maternal body mass index at booking is associated with an increased risk of prolonged pregnancy and increased rate of IOL. Despite this, more than 60% of obese primiparous and 90% of multiparous women with prolonged pregnancies who were induced achieved vaginal delivery and labour complications in the obese women with prolonged pregnancies were largely comparable to those of normal weight women with prolonged pregnancies. Our data suggest that IOL for prolonged pregnancy in obese women is a reasonable and safe management option. [ABSTRACT FROM AUTHOR]

In this short review, we discuss how recent insights into myometrial physiology may be taken forward and translated into much-needed novel therapies for problems associated with labour. We consider excitation-contraction coupling in the myometrium and how this relates to our understanding of the changes that occur to produce myometrial contractions and successful labour. We then discuss how this information has already been used in the development of drugs to either stimulate or relax the myometrium, to address the needs of women with either slow (dystocic) labours or threatened preterm labours, respectively. We next present the data showing how basic physiological findings pertaining to hypoxia and lactate production have been taken and translated into a tool for predicting and thus better managing difficult labours. We then highlight examples of where physiological research has started to provide mechanistic insight into clinical problems associated with labour and parturition (obesity, diabetes, advanced maternal age, postdate and twin pregnancies) and suggest how these findings could be translated into new therapies for difficult labours.