Using Active and Passive Near-Field Hydrophones to Image the Near-Surface in Ultra-Shallow Waters Offshore Abu Dhabi

Seismic surveys are generally designed to image deep reservoirs, which leaves the near-surface woefully under-sampled. This is particularly a challenge offshore Abu Dhabi, where a complex near-surface – with karstic collapses and meandering channels – contaminates the seismic image with strong footprints. To mitigate these effects, we use near-field hydrophone data, primarily designed to QC the airgun source, for near-surface imaging. Near-field hydrophones (NFH) are positioned about a meter above each airgun and are designed to record the source near-field pressure. They immediately capture dysfunctional or out-of-spec guns, which alerts the recording crew. Yet, in a shallow water environment, they unintentionally record seismic reflections from the near-surface, which we will use for seismic imaging. Streamer vessels usually use two source arrays, 50 meters apart, which shoot in a flip-flop mode. The active NFH refer to the recordings directly above the shooting guns, while the passive NFH refer to the recordings from the array that is not shooting. Because the passive NFH are less contaminated by the source near-field, they are typically the preferred choice for near-surface imaging. Waters are too shallow in offshore Abu Dhabi to use streamer vessels. Instead, seismic surveys involve ocean-bottom cables (OBC) or nodes (OBN) and smaller airgun arrays. The shooting vessels can be single-source or dual-source. While a single source vessel has only active NFH, a dual source vessel has both active and passive NFH. However, even if a dual-source vessel is used, the 50 m distance between the shooting source array and the passive NFH is too large to capture the water-bottom reflection for water-depths shallower than 25 m. For these reasons, we propose to combine both measurements, using active NFH for the very shallow section and passive NFH for the deeper section. We have applied this technique to a recent node survey acquired offshore Abu Dhabi. By combining the active and passive NFH, a very high-resolution shallow image was obtained, which allows the interpretation of geological layers just below the water bottom. Comparisons with high resolution 2D site survey images show good agreement. Given the NFH do not require any additional acquisition and are delivered as a byproduct of standard seismic surveys, we have demonstrated that proper use of NFH can provide high quality images for pre-site survey interpretation, which reduces the need for additional – and expensive – geotechnical surveys. This is the first published use of combined active and passive NFH in Abu Dhabi shallow waters for the purpose of imaging. The resolution of the shallow formation images allows detailed interpretation not achievable using conventional seismic data. In the long term, this technique may reduce the need for additional site survey acquisitions.

The developing kidney actively negotiates geometric packing conflicts to avoid defects

The physiological functions of several organs rely on branched tubular networks, but little is known about conflicts in development between building enough tubules for adequate function and geometric constraints imposed by organ size. We show that the mouse embryonic kidney epithelium negotiates a physical packing conflict between tubule tip duplication and limited area at the organ surface. Imaging, computational, and soft material modeling of tubule 'families' identifies six geometric packing phases, including two defective ones. Experiments in kidney explants show that a retrograde tension on tubule families is necessary and sufficient for them to avoid defects by switching to a vertical orientation that increases packing density. These results reveal developmental contingencies in response to physical limitations, and create a framework for classifying kidney defects.

Reproducibility of Novel Soft-Tissue Landmarks on Three-Dimensional Human Facial Scan Images in Caucasian and Asian

Background Three-dimensional surface imaging is established in many disciplines for objective facial acquisition regarding anthropometry. Former studies addressed the validation of landmark-based measurements for single race. In order to distinguish racial difference, the reproducibility of the landmark measurements must first be validated. Objectives Our purpose is to validate the reproducibility of 46 facial soft-tissue landmarks on x, y, z axes to prove their reliability as 3D reference points. Methods The study included 80 European Caucasian and 80 Chinese volunteers. Standardized 3D surface imaging was performed using Vectra 3D system. Two raters identified and defined 46 landmarks (138 coordinates), then repeatedly 3D-imaged volunteers' facial region in separate sessions. Coordinates' reproducibility of landmarks is divided into three categories (< 0.5 mm, < 1 mm, and >1 mm) for intra- and inter-rater reproducibility assessments. Results Coordinates' reproducibility of 160 samples was distributed as follows: Intra-rater: < 0.5 mm (45%), < 1 mm (42%), >1 mm (13%); inter-rater: < 0.5 mm (31.2%), < 1 mm (42%), > 1 mm (26.8%). The reproducibility of landmarks in nasal tip region differs slightly between Caucasians and Asians. Compared to females, males typically have higher landmark reproducibility in lip and chin region. However, there were no differences in the reproducibility ranking of landmarks by gender. Conclusion The majority of the 46 landmarks in the 3D plane are reproducible to 1 mm, which is clinically acceptable. All selected landmarks showed strong consistency across race and gender, suggesting their potential use as reference points in prospective clinical practice. Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Digital Leg Volume Quantification: Precision Assessment of a Novel Workflow Based on Single Capture Three-dimensional Whole-Body Surface Imaging

Whole-body three-dimensional surface imaging (3DSI) offers the ability to monitor morphologic changes in multiple areas without the need to individually scan every anatomical region of interest. One area of application is the digital quantification of leg volume. Certain types of morphology do not permit complete circumferential scan of the leg surface. A workflow capable of precisely estimating the missing data is therefore required. We thus aimed to describe and apply a novel workflow to collect bilateral leg volume measurements from whole-body 3D surface scans regardless of leg morphology and to assess workflow precision. For each study participant, whole-body 3DSI was conducted twice successively in a single session with subject repositioning between scans. Paired samples of bilateral leg volume were calculated from the 3D surface data, with workflow variations for complete and limited leg surface visibility. Workflow precision was assessed by calculating the relative percent differences between repeated leg volumes. A total of 82 subjects were included in this study. The mean relative differences between paired left and right leg volumes were 0.73 ± 0.62% and 0.82 ± 0.65%. The workflow variations for completely and partially visible leg surfaces yielded similarly low values. The workflow examined in this study provides a precise method to digitally monitor leg volume regardless of leg morphology. It could aid in objectively comparing medical treatment options of the leg in a clinical setting. Whole-body scans acquired using the described 3DSI routine may allow simultaneous assessment of other changes in body morphology after further validation.