Distal Footprint Research Articles

Leveraging Domain Expertise in Machine Learning for Critical Metal Prospecting in the Oslo Rift: A Case Study for Fe-Ti-P-Rare Earth Element Mineralization

Global demand for critical raw materials, including phosphorus (P) and rare earth elements (REEs), is on the rise. The south part of Norway, with a particular focus on the Southern Oslo Rift region, is a promising reservoir of Fe-Ti-P-REE resources associated with magmatic systems. Confronting challenges in mineral exploration within these systems, notably the absence of alteration haloes and distal footprints, we have explored alternative methodologies. In this study, we combine machine learning with geological expertise, aiming to identify prospective areas for critical metal prospecting. Our workflow involves processing over 400 rock samples to create training datasets for mineralization and non-mineralization, employing an intuitive sampling strategy to overcome an imbalanced sample ratio. Additionally, we convert airborne magnetic, radiometric, and topographic maps into machine learning-friendly features, with a keen focus on incorporating domain knowledge into these data preparations. Within a binary classification framework, we evaluate two commonly used classifiers: a random forest (RF) and support vector machine (SVM). Our analysis shows that the RF model outperforms the SVM model. The RF model generates a predictive map, identifying approximately 0.3% of the study area as promising for mineralization. These findings align with legacy data and field visits, supporting the map’s potential to guide future surveys.

Minimally Invasive Distal Biceps Tendon Reconstruction With Semitendinosus Allograft and Dual Unicortical Button Fixation

Complete rupture of the distal biceps tendon is routinely treated with direct repair; however, chronic, mid-substance, or musculotendinous tears are challenging clinical scenarios for surgeons. Although attempts at direct repair should be considered, in cases of severe retraction or tendon deficiency, a reconstruction may be warranted. Herein the authors describe a technique for distal biceps reconstruction using allograft with a Pulvertaft weave via a standard anterior incision, similar to primary repair, with a small catchment incision more proximally for tendon retrieval. Use of this technique with dual unicortical buttons allows for early range of motion, restoration of the distal footprint, and improved biomechanical construct strength, which has proven invaluable in a population of elite and highly active military servicemembers.

Lithogeochemistry in exploration for intrusion-hosted magmatic Ni–Cu–Co deposits

Magmatic Ni–Cu–Co–platinum group element deposits are notoriously difficult exploration targets owing to a lack of alteration haloes or other extended distal footprints. Success requires prediction of prospective terranes, followed by identification of suitable host intrusions and deposition sites within those intrusions. At the regional scale, potential ore-hosting magmas tend to have lithophile trace element trends falling on mixing lines between primitive or slightly depleted source mantle and typical upper continental crust, with several significant exceptions. Most known deposits have parent magmas that are in the upper range of FeO content for given MgO compared with baseline data sets for continental large igneous province magmas. At the scale of individual intrusions, the presence of cumulate rocks, both mafic and ultramafic, is key. These can be recognized in regional datasets using combinations of magnesium number (molar MgO/(MgO + FeO), Al 2 O 3 , TiO 2 and Zr contents. Combinations of alteration-resistant element ratios between Ni, Cr and Ti are also useful and can also be applied to moderately weathered samples. Concentrations and ratios of Cu and Zr are useful in discriminating chalcophile-enriched and depleted magma suites. In combination, these approaches can be combined to discriminate highly prospective cumulate-dominated magmatic suites and individual intrusions from non-cumulate suites with limited potential. Supplementary material: Supplementary Appendix 1, procedure for determination of FeO–MgO contents of magmas from olivine-liquid mixing lines, and Supplementary Appendix 2, procedure and error analysis for correcting major element whole rock analyses volatile and sulfide free, are available at https://doi.org/10.6084/m9.figshare.c.6267664

Anatomic evaluation of the insertional footprints of the iliofemoral and ischiofemoral ligaments: a cadaveric study

BackgroundAn understanding of the insertional footprints of the capsular ligaments of the hip is important for preserving hip function and stability given the increasing number of minimally invasive hip surgeries being performed under a limited surgical view. However, it is difficult to detect these ligaments intraoperatively and many surgeons may not fully appreciate their complex anatomy. The aims of this study were to quantify the proximal and distal footprints of the iliofemoral ligament (ILFL) and ischiofemoral ligament (ISFL) and to estimate the location of the corresponding osseous landmarks on the proximal femur, which can be detected easily during surgery.MethodsTwelve hip joints from Japanese fresh frozen cadavers were used. All muscle, fascia, nerve tissue, and vessels were removed to expose the intact capsular ligaments of the hip. The length and width of the proximal and distal footprints of the ILFL and ISFL were measured and their relationship to osseous structures was evaluated, including the intertrochanteric line, femoral neck, and lesser trochanter.ResultsThe mean length of the distal medial arm of the ILFL footprint was 17.9 mm and the mean width was 9.0 mm. The mean length of the distal lateral arm of the ILFL footprint was 23.0 mm and the mean width was 9.7 mm. For the footprint of the medial arm, the insertion was in the distal third of the intertrochanteric line and that of the lateral arm was in the proximal 42% of this line. The mean distance from the lesser trochanter to the footprint of the medial arm was 24.6 mm. The mean length of the distal ISFL footprint was 11.3 mm and the mean width was 6.9 mm. The footprint of the distal ISFL was located forward of the femoral neck axis in all specimens.ConclusionsUnderstanding the size and location of each capsular ligament footprint in relation to an osseous landmark may help surgeons to manage the hip capsule intraoperatively even under a narrow surgical view. The findings of this study underscore the importance of recognizing that the distal ISFL footprint is located relatively forward and very close to the distal lateral arm footprint.

The tibialis posterior tendon footprint: an anatomical dissection study

BackgroundThe tibialis posterior tendon (TPT) is the main dynamic stabilizer of the medial longitudinal arch of the foot. Especially in adult acquired flatfoot deformity (AAFD) the TPT plays a detrimental role. The pathology and function of the tendon have been extensively investigated, but knowledge of its insertional anatomy is paramount for surgical procedures. This study aimed to analyze the complex distal footprint anatomy of the TPT.MethodsForty-one human anatomical specimens were dissected and the distal TPT was followed to its bony footprints. After tendon removal the footprints were marked with ink. Standardized photographs were taken and consecutively analyzed by digital imaging measurements. Footprint length, width, area of insertion, location, and shape was studied regarding the main insertion at the navicular bone.ResultsAll specimens had the main TPT insertion at the navicular bone (41/41, 100%). Sixty-three percent of navicular TPT insertions were located at the plantar aspect. The mean navicular footprint measured 12.1 mm × 6.9 mm in length and width, respectively. The tendon further spread into several slips which anchored the tibialis posterior deep in the plantar arch. TPT insertions were highly variable with an involvement of up to eight distinct bony footprints in the mid- and hindfoot. The second most common additional footprint was the lateral cuneiform (93% of dissected feet), followed by the medial cuneiform (80%), the metatarsal bases [1–5] (80%), the cuboid (46%), the intermediate cuneiform (19%), and the calcaneus (12%).ConclusionsThe present study adds to current knowledge on the footprint anatomy of the TPT. Based on the findings of this study we advocate a plantar location of flexor digitorum longus tendon transfer in flexible AAFD in order to restore the anatomical lever and insertion of the TPT.

Qualitative and Quantitative Analyses of the Dynamic and Static Stabilizers of the Medial Elbow: An Anatomic Study

Background: The anterior bundle of the medial ulnar collateral ligament (UCL) and the forearm flexors provide primary static and dynamic stability to valgus stress of the elbow in overhead-throwing athletes. Quantitative anatomic relationships between the dynamic and static stabilizers have not been described. Purpose: To perform qualitative and quantitative anatomic evaluations of the medial elbow-UCL complex with specific attention to pertinent osseous and soft tissue landmarks. Study Design: Descriptive laboratory study. Methods: Ten nonpaired, fresh-frozen human cadaveric elbows (mean age, 54.1 years [range, 42-64 years]; all male) were utilized for this study. Quantitative analysis was performed with a 3-dimensional coordinate measuring device to quantify the location of pertinent bony landmarks and tendon and ligament footprints on the humerus, ulna, and radius. Results: The anterior bundle of the UCL attached 8.5 mm (95% CI, 6.9-10.0) distal and 7.8 mm (95% CI, 6.6-9.1) lateral to the medial epicondyle, 1.5 mm (95% CI, 0.5-2.5) distal to the sublime tubercle, and 7.3 mm (95% CI, 6.1-8.5) distal to the joint line on the ulna along the ulnar ridge. The flexor digitorum superficialis (FDS) ulnar tendinous insertion was closely related and interposed within the anterior bundle of the UCL, overlapping with 45.6% (95% CI, 38.1-53.6) of the length of the anterior bundle of the UCL. The flexor carpi ulnaris (FCU) attached 1.9 mm (95% CI, 0.8-2.9) posterior and 1.3 mm (95% CI, 0.6-3.2) proximal to the sublime tubercle and overlapped with 20.9% (95% CI, 7.2-34.5) of the area of the distal footprint of the anterior bundle of the UCL. Conclusion: The anterior bundle of the UCL had consistent attachment points relative to the medial epicondyle and sublime tubercle. The ulnar limb of the FDS and FCU tendons demonstrated consistent insertions onto the ulnar attachment of the anterior bundle of the UCL. These anatomic relationships are important to consider when evaluating distal UCL tears both operatively and nonoperatively. Excessive stripping of the sublime tubercle should be avoided during UCL reconstruction to prevent violation of these tendinous attachments. Clinical Relevance: The findings of this study enhance the understanding of valgus restraint in throwing athletes and provide insight into the difference in nonoperative outcomes between proximal and distal tears of the UCL.

Mapping temporal and spatial patterns of zircon U-Pb disturbance: A Yilgarn Craton case study

The zircon U-Pb system is a robust geochronometer, however disturbance to this system can be widely diagnosed on U-Pb concordia diagrams where it is typically interpreted as a consequence of radiogenic-Pb loss. In many cases, removal of radiogenic-Pb is not complete, and Discordia regressions on concordia diagrams may then potentially track both the original age of crystallization of the rock, and the timing of isotopic disturbance. However, U-Pb disturbance, resulting in normal discordance, can also be driven by U gain. In this contribution, we expand on a novel approach to determine the most pervasive time of U-Pb disturbance in a sample. We introduce the Concordant-Discordant Comparison (CDC) test which evaluates the similarity between a sample's concordant age structure and a modelled age structure, from discordant analyses, over a wide range of potential disturbance times. The closest similarity in concordant and discordant age populations as derived from a specified time of elemental mobility, is interpreted as the best estimate for the time of U-Pb disturbance. The CDC test is appropriate for magmatic as well as detrital samples, and yields dates that can be spatially interpolated to produce regional maps that define domains of U-Pb disturbance.We highlight the application of the CDC test using a case study from the Eastern Goldfields Superterrane of the Yilgarn Craton, Western Australia. U-Pb SIMS analysis of 95 zircon samples from across the Eastern Goldfields Superterrane reveals two dominant times of U-Pb disturbance – recent and at ~600Ma. The ~600Ma time of U-Pb disturbance shows a statistically significant spatial relationship to a buried set of undated dykes (the Cosmo Newbery Dyke Suite), which are apparent in geophysical images. Thermal modelling indicates dyke temperatures alone are insufficient to cause widespread Pb loss in host rock zircon. We therefore suggest dyke emplacement caused U-Pb disturbance through reactive fluids leaching radiogenic-Pb. Additionally, we use the difference between the measured and calculated zircon Th/U ratio to distinguish between Pb loss and elemental gain processes, as the calculated Th/U ratio derived from 208Pb/206Pb will only match measured Th/U where no later addition or loss of Th or U has occurred. CDC modelling of discordant U-Pb zircon analyses may provide a means to recognise the distal footprint of otherwise difficult to date tectonothermal events and extract useful information from often discarded analyses.

Passive seismic studies show configuration of Paleoproterozoic subduction zones and their role in craton assembly in Western Australia

The Capricorn Orogen Passive source Array (COPA) is the passive source seismic component of a major Science and Industry Endowment Fund (SIEF) project, “The distal footprints of giant ore systems: Capricorn case study”. COPA focuses on the deep crustal and shallow lithospheric structure in the Capricorn Orogen with the aim to better understand the tectonic amalgamation of the Western Australian Craton. The objective of COPA is to produce 3D multiple scale seismic images across the orogeny, that together with other geological and geophysical datasets help constrain the timing and kinematic evolution of Capricorn Orogen’s fault zones, and their role in the metallogenic history.

Arthroscopic anatomical reconstruction of the lateral ankle ligaments: A technical simplification

Anatomical reconstruction of the lateral ankle ligaments has become a pivotal component of the treatment strategy for chronic ankle instability. The recently described arthroscopic version of this procedure is indispensable to ensure that concomitant lesions are appropriately managed, yet remains technically demanding. Here, we describe a simplified variant involving percutaneous creation of the calcaneal tunnel for the distal attachment of the calcaneo-fibular ligament. The rationale for this technical stratagem was provided by a preliminary cadaver study that demonstrated a correlation between the lateral malleolus and the distal footprint of the calcaneo-fibular ligament. The main objectives are simplification of the operative technique and decreased injury to tissues whose function is crucial to the recovery of proprioception.

Subscapularis Tendon Tears: Identifying Mid to Distal Footprint Disruptions

We present an arthroscopic technique used to identify mid to distal subscapularis tendon disruptions. These tears can be easy to miss and require a thorough arthroscopic evaluation of the medial biceps sling and the medial side wall of the bicipital groove to detect. The arthroscopic procedure is performed with the patient in the lateral decubitus position, and the same portals used for standard subscapularis repair are used for this technique. If a high degree of clinical suspicion exists for subscapularis pathology and no tendon disruption is initially identified, an inspection of the medial biceps sling and medial side wall of the bicipital groove may show mid to distal subscapularis tendon disruptions. A 70° arthroscope is essential in visualizing the medial sling, the subscapularis tendon, the biceps tendon, and the proximal 2 cm of the bicipital groove. Any disruptions or rents in the medial sling or medial side wall are suggestive of a subscapularis tear. Once a tear is identified, we proceed with a biceps tenodesis and then take down the medial sling from the lesser tuberosity to better delineate the subscapularis footprint. The subscapularis may then be repaired in standard fashion.

Evidence for three major transcription activation elements in the proximal mouse proalpha2(I) collagen promoter.

In vivo transient expression and in vitro transcription experiments indicated that a segment between -170 and -40 bp upstream of the start of transcription of the mouse proalpha2(I) collagen gene was essential to activate transcription. DNase I protection experiments identified three strong footprints in this segment. Experiments with deletion mutants encompassing the sequences defined by these three footprints indicated that each of the three elements contributed to the transcriptional activity of the promoter. All three elements are GC-rich, redundant sites for a complex set of DNA binding proteins that includes SP1, other proteins that bind to an SP1 consensus site and proteins that bind to a Krox consensus site. In addition, the segment corresponding to the most proximal footprint also binds the multimeric CCAAT binding protein CBF. Addition of an excess amount of oligo- nucleotides corresponding to either of the two distal footprints significantly inhibited in vitro transcription of the -350 bp proalpha2(I) collagen promoter. Anti-SP1 antibodies that completely inhibited transcription of the early SV40 promoter had little effect on transcription of the wild-type -350 bp promoter, suggesting that SP1 has only a minor role in activity of this promoter. Our results show that the segment between base pairs -170 and -40 of the proalpha2(I) collagen promoter, which contains redundant binding sites for a complex set of nuclear proteins, is essential in the transcriptional activity of this promoter in fibroblasts.

Structure-Function Analysis of the Rat Prolactin Promoter: Phasing Requirements of Proximal Cell-Specific Elements

Expression of PRL, a member of the GH family of genes, is restricted to the lactotroph cells of the anterior pituitary. The proximal promoter of the rat PRL (rPRL) gene contains four factor-binding sites. Three nonadjacent elements, footprints (FP) I, III, and IV, are separated by an integral number of helical turns and bind a pituitary-specific factor, LSF-1. FP II binds another factor present in pituitary and nonpituitary cells. The mechanisms by which DNA-bound proteins influence RNA polymerase-II activity over large distances are not fully understood, but protein-protein interactions, with looping of intervening DNA, may bring distant sites into close proximity. Here, we demonstrate, using protein titration studies, that LSF-1 binds to the most proximal FP I element with the highest affinity, whereas it binds the more distal elements, FP III and FP IV, with progressively lower affinities. Time-course and salt-sensitivity studies reveal that binding of LSF-1 to all three pituitary-specific rPRL promoter sites occurs rapidly (less than or equal to 1 min) and requires fairly high salt concentrations (greater than or equal to 300 mM KCl) to destabilize protein-DNA interactions. Moreover, once bound, the pituitary nuclear factor(s) induces a conformational change in rPRL DNA structure with greatly delayed kinetics (greater than 15 min) and at a different salt concentration than are required for simply factor binding. Taken together, these data suggest a model in which LSF-1 initially binds fairly rapidly to multiple nonadjacent elements and then interacts with itself or other DNA-bound proteins much more slowly, possibly looping or bending the rPRL promoter.(ABSTRACT TRUNCATED AT 250 WORDS)