A randomised non-inferiority controlled trial of a single versus a four intradermal sterile water injection technique for relief of continuous lower back pain during labour

Background: Almost one third of women suffer continuous lower back pain during labour. Evidence from three systematic reviews demonstrates that sterile water injections (SWI) provide statistically and clinically significant pain relief in women experiencing continuous lower back pain during labour. The most effective technique to administer SWI is yet to be determined. Therefore, the aim of this study is to determine if the single injection SWI technique is no less effective than the routinely used four injection SWI method in reducing continuous lower back pain during labour.Methods/design: The trial protocol was developed in consultation with an interdisciplinary team of clinical researchers. We aim to recruit 319 women presenting at term, seeking analgesia for continuous severe lower back pain during labour. Participants will be recruited from two major maternity hospitals in Australia. Randomised participants are allocated to receive a four or single intradermal needle SWI technique. The primary outcome is the change in self-reported pain measured by visual analogue scale at baseline and thirty minutes post intervention. Secondary outcomes include VAS change scores at 10, 60, 90 and 120 min, analgesia use, mode of birth and maternal satisfaction.Statistical analysis: Sample size was calculated to achieve 90% power at an alpha of 0.025 to detect a non-inferiority margin of ≤ 1 cm on the VAS, using a one-sided, two-sample t-test. Baseline demographic and clinical characteristics will be analysed for comparability between groups. Differences in primary (VAS pain score) and secondary outcomes between groups will be analysed by intention to treat and per protocol analysis using Student's t-test and ANOVA.Conclusion: This study will determine if a single intradermal SWI technique is no less effective than the routinely used four injection technique for lower back pain during labour. The findings will allow midwives to offer women requesting SWI during labour an evidence-based alternative technique more easily administered by staff and accepted by labouring women. Trial Registration: ACTRN12609000964213

Domain wall pinning and dislocations: Investigating magnetite deformed under conditions analogous to nature using transmission electron microscopy

In this study, we deformed samples cut from a single magnetite octahedron and used transmission electron microscopy (TEM) and magnetic measurements to experimentally verify earlier computational models of magnetic domain wall pinning by dislocations and to better understand the nature of dislocations in magnetite. Dislocations in magnetite have been of interest for many decades because they are often cited as a likely source of stable thermoremanent magnetizations in larger multidomain (MD) magnetite grains, so a better understanding of dislocation effects on coercivity in MD magnetite is crucial. TEM imaging shows, for the first time, domain walls sweeping through the magnetite sample and being pinned at dislocations. In agreement with theory, these findings demonstrate that domain walls are more strongly pinned at networks of dislocations than at single dislocations and that domain walls pinned at longer dislocations have higher microcoercivities than those pinned at shorter dislocations. This experimentally illustrates the ability of dislocations to increase the coercivity of larger multidomain magnetite grains. The observed values for microcoercivity and bulk coercivity are in reasonable agreement with theoretical calculations. Burgers vectors were determined for some dislocations to verify that they were in keeping with expected dislocation orientations. The dislocations were found to be primarily located on close-packed {111} planes within the magnetite. Deformation caused only a minor change in bulk coercivity, but first-order reversal curve diagrams show populations with increased coercivity not visible in hysteresis loops.The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC grant agreement 320750. The Institute for Rock Magnetism and LacCore are supported by the NSF EAR Instrumentation and Facilities Program and by the University of Minnesota, Earth Sciences Division, National Science Foundation. To obtain the data used for this paper, please contact A.K.L. This work was funded by EAR-0810085 to J.M.F., by EAR-0810252 to A.J.N., and by a Geological Society of America grant to A.K.L. This is IRM publication 1406.This is the final published version. It first appeared at http://onlinelibrary.wiley.com/doi/10.1002/2014JB011335/abstract?rememberMePresent=false

Geomagnetic field inclinations for the past 400 kyr from the 1-km core of the Hawaii Scientific Drilling Project

A volcanic record of geomagnetic field inclination for the past ∼400 kyr at Hilo, Hawaii, has been obtained from the 941.5 m of core recovered by the Hawaii Scientific Drilling Project. The analysis of 195 lava flows reveals six instances of near-zero inclination and two instances of fully negative inclination (reverse polarity) within an otherwise normal-polarity core. In particular, flow unit 23 (∼178 m depth) records a horizontal inclination and may be associated with the Laschamp event; flow units 40 and 42 (∼260 m depth) record negative inclinations and are close in age to the Blake event; and flow unit 55 (∼320 m depth) records a negative inclination with a relative declination change of ∼75° with respect to the overlying flow and is probably the Jamaica/Biwa I/Pringle Falls event. The five instances of shallow inclination found below 400 m depth appear to have resulted from long-term secular variation as they are part of inclination swings between ∼0° and ∼60° with a periodicity of ∼10–50 kyr. In contrast, the inclination shifts at ∼178 m and ∼320 m depths significantly deviate from long-term trends, suggesting the existence of at least two independent processes producing time variations of the geomagnetic field. The secular variation has a mean of 30.9° (α_(95) = 2.27°), which is significantly shallower than the expected dipole mean of 36°. The dispersion (σ = 12.5°) agrees with global paleosecular variation data for 0–5 Ma and secular variation models

Comparison of a single vs. a four intradermal sterile water injection for relief of lower back pain for women in labour : A randomised controlled trial

Objective: sterile water injections are a simple, safe, effective, non-pharmacological technique for relieving back pain in labour, however the number of injections required to achieve optimal analgesia is unknown. The objective of this trial was to evaluate the degree and duration of analgesia provided by a single injection of sterile water, compared to four injections. Design: randomised controlled non-inferiority trial. Participants and setting: three hundred and five women in labour at term, requesting analgesia for back pain were recruited from two metropolitan hospitals in Brisbane, Australia. Intervention: participants were randomly assigned to receive either one (n=147) or four (n=158) sterile water injections. Outcome measures: difference in self-reported pain measured using a visual analogue scale (VAS) between baseline and 30. mins post-intervention. The clinically acceptable margin of difference was defined as ≤1. cm on the VAS between the single injection compared to four injection technique. Secondary outcomes include VAS score on injection and 10, 60, 90 and 120. mins post-intervention, analgesia use, mode of birth and maternal satisfaction. Findings: the mean difference in the pre and post (30. mins) injection scores between two groups was -1.48. cm (95% CI -2.10, -0.86) in favour of the FI technique, however the injection pain associated with the FI was significantly greater than that of the SI technique (

Middle/Late Pleistocene relative palaeointensity of the geomagnetic field from lacustrine sediments, Lake Chewaucan, western United States

Detailed palaeomagnetic and rock magnetic studies of a 15 m succession of Middle/Late Pleistocene lacustrine sediments from ancient Lake Chewaucan, southern Oregon, western United States, indicate that the remanence-bearing grains are sufficiently uniform to be applicable to relative palaeointensity studies. We have used ARM, SIRM and ? for normalization of the NRM. All three parameters give essentially identical results in their relative stratigraphic variations, which indicates that the normalizations efficiently remove the effects of variation in magnetic mineral concentration. Patterns in grain-size variation, as indicated by small-scale quasi-cyclic fluctuations in hysteresis parameters, may be due to environmental changes such as lake-level variation. However, these fluctuations are within the acceptable range of grain sizes for palaeointensity studies and cannot be correlated with any of the features of the normalized remanence record. We therefore conclude that the large-scale variations in the normalized remanence record are due to geomagnetic palaeointensity fluctuations. Parts of the normalized remanence record, where firm chronological constraints exist, may correlate with features of relative palaeointensity records from deep-sea sediments. Our results also confirm the observation that low geomagnetic field intensities dominate during geomagnetic excursions. Further studies of relative palaeointensity of the geomagnetic field may enable the development of an independent time-scale which would make possible the direct correlation of palaeoclimate records from deep-sea and continental environments.<br/

The Blake geomagnetic excursion recorded in a radiometrically dated speleothem

One of the most important developments in geomagnetism has been the recognition of polarity excursions of the Earth’s magnetic field. Accurate timing of the excursions is a key point for under standing the geodynamo process and for magnetostratigraphic correlation. One of the best-known excursions is the Blake geomagnetic episode, which occurred during marine isotope stage MIS 5, but its morphology and age remain controversial. Here wes how, for the first time, the Blake excursion recorded in a stalagmite which was dated using the uranium-series dis equilibrium techniques. The characteristic remanent magnetisation is carried by fine-grained magnetite. The eventis documented by two reversed intervals (B1 and B2). The age of the eventis estimated to be between 116.5 ± 0.7 kyr BP and 112.0 ± 1.9 kyr BP, slightly younger (~3–4 kyr) than recent estimations from sedimentary records sated by astronomical tuning. Low values of relative palaeointensity during the Blake episode are estimated, but a relative maximum in the palaeofield in tensity coeval with the complete reversal during the B2 interval was observed. Duration of the Blake geomagnetic excursion is 4.5 kyr, two times lower than single excursions and slightly higher than the stimated diffusion time for the inner core (~3 kyr)