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The southern Indian Ocean has several prominent aseismic ridges recognized as oceanic large igneous provinces (i.e., the Madagascar Ridge, Del Cano Rise, Crozet Plateau, and Conrad Rise) in the off-axis areas of the Southwest Indian Ridge (SWIR). However, previously obtained magnetic survey lines are sparse and not correctly aligned with the seafloor spreading direction; thus, the detailed spreading history, including the formation of these aseismic ridges, remains an open question. We reconstructed the tectonic history of two segments between the Discovery II and Gallieni fracture zones in the SWIR using newly obtained magnetic data (total and vector magnetic field) and an open-source magnetic dataset. We revealed that the southern Madagascar Ridge and the Del Cano Rise once formed a single bathymetric high and separated by at least Chron 30y, which is quite different from the global age model. In addition, the rises may have formed before Chron 34y, assuming an extinct ridge south of the Del Cano Rise. The two rises have been recognized as having formed by Marion hotspot plume-induced excess volcanism around the active spreading ridge of the SWIR, which can explain locally isostatically compensated thicker-than-normal crust. However, linear magnetic anomalies have not been observed across the main part of these rises, suggesting that magmatic activity controlled by seafloor spreading is unlikely. Like other aseismic ridges in the southern Indian Ocean, these two rises may possibly have been formed partly by continental fragments rather than plume-induced excess volcanism. Plain Language Summary The southern Indian Ocean contains several bathymetric high regions previously interpreted as oceanic large igneous provinces. Hotspot-ridge interaction is considered the key factor in the formation of such large volcanic structures. However, the detailed seafloor spreading history and origin of these large volcanic structures are not understood as well as those in other oc

Transanal total mesorectal excision is a relatively new approach for treating lower rectal cancer. Carbon dioxide embolism is a critical complication of this procedure. We report the case of a 69-year-old man with lower rectal cancer who underwent transanal total mesorectal excision followed by laparoscopic low anterior resection. He had a sudden intraoperative carbon dioxide embolism during the transanal mesorectal excision. During the ventral dissection of the rectum, end-tidal carbon dioxide and blood oxygen saturation suddenly decreased. We stopped the insufflation of carbon dioxide and suspended the procedure. There was no circulatory collapse, and the vital signs gradually recovered; therefore, we resumed the surgery approximately 30 minutes later and completed it without additional complications. Upon reviewing the video, we found a small injured vein that would aspirate carbon dioxide. These findings suggested that careful hemostasis is essential to prevent carbon dioxide embolus during transanal total mesorectal excision.

This study examines the seasonal evolution of Cape Darnley Bottom Water (CDBW), using the results of mooring and hydrographic measurements in the slope region off Cape Darnley in 2008-2009 and 2013-2014. Newly formed CDBW began reaching the western and nearshore part of the slope region off Cape Darnley in April, spread to the offshore and eastern part in May, and reached the easternmost part in September. The potential temperature and salinity decreased and the neutral density increased when newly formed CDBW reached mooring sites. Potential temperature-salinity properties of CDBW changed over time and location. The salinity of the source water of CDBW estimated from potential temperature-salinity diagrams started to increase at a nearshore mooring in late April, which is about 2 months after the onset of sea-ice production, and continued to increase during the ice production season. It is most probable that the accumulation of brine in the Cape Darnley polynya produces the seasonal variation of potential temperature-salinity properties of CDBW. Two types of CDBW were identified. Cold and less saline CDBW and warm and saline CDBW were present in Wild and Daly Canyons, respectively. This indicates that the salinity of the source water of CDBW increased in the westward direction. CDBW exhibited short-term variability induced by baroclinic instability.

Introduction: Necrotizing soft tissue infection (NSTI) of the chest wall is a rare, rapidly spreading, highly lethal surgical disease. Radical debridement interferes with the important anatomical function of the chest wall. We re-port a case of chest wall NSTI that was successfully managed with early diagnosis and serial debridement. Presentation of case: A 43-year-old, previously healthy woman presented with severe malaise and worsening right axillary pain. She was severely lethargic and had a painful, large, pale lesion with surrounding erythema of the right chest and trunk. Computed tomography revealed NSTI, with diffuse soft tissue inflammation extending from the axilla to the lower abdomen. There was no obvious entry portal. Prompt surgical drainage was established. Group A streptococcus infection was diagnosed. During her 3-month postoperative course, she underwent four more surgeries, including two debridements. This treatment proved successful and avoided the need for complicated muscle flap reconstruction. She was discharged on postoperative day 109. Discussion: Group A streptococcus can cause NSTI even in immunocompetent patients without an entry portal. Radical debridement is recommended for infection control. Preserving anatomical chest wall function, however, is also important. Serial debridement with close follow-up solved the problem in this patient. Conclusions: Serial debridement with close follow-up enabled to avoid large tissue deficits and complicated re-construction in the case of NSTI of the chest wall. (C) 2021 The Author(s). Published by Elsevier Ltd on behalf of IJS Publishing Group Ltd.

This study examines the seasonal evolution of Cape Darnley Bottom Water (CDBW), using the results of mooring and hydrographic measurements in the slope region off Cape Darnley in 2008-2009 and 2013-2014. Newly formed CDBW began reaching the western and nearshore part of the slope region off Cape Darnley in April, spread to the offshore and eastern part in May, and reached the easternmost part in September. The potential temperature and salinity decreased and the neutral density increased when newly formed CDBW reached mooring sites. Potential temperature-salinity properties of CDBW changed over time and location. The salinity of the source water of CDBW estimated from potential temperature-salinity diagrams started to increase at a nearshore mooring in late April, which is about 2 months after the onset of sea-ice production, and continued to increase during the ice production season. It is most probable that the accumulation of brine in the Cape Darnley polynya produces the seasonal variation of potential temperature-salinity properties of CDBW. Two types of CDBW were identified. Cold and less saline CDBW and warm and saline CDBW were present in Wild and Daly Canyons, respectively. This indicates that the salinity of the source water of CDBW increased in the westward direction. CDBW exhibited short-term variability induced by baroclinic instability.

The Antarctic Ice Sheet (AIS) is one of the largest potential contributors to future sea-level changes. Recently, an acceleration of AIS volume loss through basal melting and iceberg calving has been reported based on several studies using satellite observations, including radar altimetry, interferometer, and gravity measurements. A recent model that couples ice sheet and climate dynamics and incorporates hydrofracturing mechanism of buttressing ice shelves predicts a higher sea-level rise scenario for the next 500 years. However, the calibration and reproducibility of the sea-level rise projection from these models relies on geological sea-level reconstructions of past warm intervals. This suggests that a highly reliable reconstruction of the past AIS is essential for evaluating its stability and anticipating its contribution to future sea-level rise. In particular, a relative sea-level reconstruction in East Antarctica is the key to solving the problems and refining future projections. The current understanding of sea-level change along the East Antarctic margin is reviewed, including Glacial Isostatic Adjustment (GIA) effects, and a new strategy is proposed to address this topic based on seamless sediment coring from marine to lake in the East Antarctic margin. This project will provide essential data on AIS change since the last interglacial period.

The India-Antarctica separation is still an open problem due to the absence of critical geophysical data. So far no wide-angle data existed along the conjugate margins of East India and the Enderby Land off East Antarctica to define the position and composition of the continent-ocean boundary - a pre-requisite for any sound reconstruction. Furthermore, along both margins only old marine magnetic random track data are available for identifying seafloor spreading anomalies to describe the drift of both continents in the Cretaceous. The Kerguelen Plateau, located just north of the East Antarctica coast, however, has been drilled several times providing the only reliable age constraint on the formation of this huge magmatic plateau. In general, the poor information resulted a wide variety of kinematic models for the drift of the India. In the last years several newly acquired geophysical data provide new constraints on its drift. Two deep seismic sounding lines off Prydz Bay and across the Princess Elisabeth Trough show that oceanic crust is already present much closer to the present-day shelf break than previously known. Magnetic data acquired parallel to these lines provide excellent timing constraints for the initial breakup of India. Finally, marine magnetic data gathered in 2017 south of Sri Lanka indicate that here the oceanic crust is definitely younger than magnetic chron M0, questioning several kinematic models for the Indian Ocean. The latest results will be presented.

Discriminating magnetic minerals of different origins in natural samples is useful to reveal their associated geological and environmental processes, which can be achieved by the analysis of remanent magnetization curves. The analysis relies on the choice of the model distribution to unmix magnetic components. Three model distributions were proposed in past studies, namely, the lognormal, skew normal, and skewed generalized Gaussian distributions, which are related to the normal distribution. In this study, the Burr type XII distribution is tested and compared with existing model distributions. An automated protocol is proposed to assign parameters necessary to initiate the component analysis, which improves the efficiency and objectivity. Results show that the new model distribution exhibits similar flexibility to the skew normal and skewed generalized Gaussian distributions in approximating skewed coercivity distributions and can fit end‐member components better than the commonly used lognormal distribution. We demonstrate that the component analysis is sensitive to model distribution as well as measurement noise. As a consequence, the decomposition is subject to bias that is hard to identify due to the lack of ground‐truth data. It is therefore recommended to compare results derived from various model distributions to identify spurious components.