Similar Depth Research Articles

The effect of spill change on reliable absolute dosimetry in a synchrotron proton spot scanning system.

Absolute dosimetry measurement is an integral part of Treatment Planning System (TPS) commissioning and it involves measuring the integrated absorbed dose to water for all energies in a pencil beam scanning delivery system. During the commissioning of Singapore's first proton therapy center, a uniform scanned field with an Advanced Markus chamber method was employed for this measurement, and a large dose fluctuation of at least 5% was observed for 10% of the energy layers during repeated measurements. This study aims to understand the root cause of this fluctuation by relating the actual delivered spot information in the log file with the charge measurement by the ion chambers. A dedicated pencil beam dose algorithm was developed, taking into account the log file parameters, to calculate the dose for a single energy layer in a homogeneous water phantom. Three energies, 70.2, 182.7, and 228.7 MeV were used in this study, with the 182.7 MeV energy exhibiting large dose fluctuation. The dose fluctuation was investigated as a function of detector's sizes (pinpoint 3D, Advanced Markus, PTW 34070, and PTW 34089) and water depth (2, 6, and 20cm). Twelve ion chambers measurements were performed for each chamber and depth. The comparison of the theoretically predicted integrated dose and the charge measurement served as a validation of the algorithm. About 5.9% and 9.6% dose fluctuation were observed in Advanced Markus and pinpoint 3D measurements at 2cm depth for 182.7 MeV, while fluctuation of 1.6% and 1.1% were observed in Advanced Markus with 228.7 and 70.2 MeV at similar depth. Fluctuation of less than 0.1% was observed for PTW34070 and PTW 34089 for all energies. The fluctuation was found to diminish with larger spot size at 20cm depth to 1.3% for 182.7 MeV. The theoretical and measured charge comparison showed a high linear correlation of for all datasets, indicating the fluctuation originated from the delivered spot characteristics. The cause of fluctuation was identified to be due to the spill change occurring close to the detector, and since the spot positional deviation profiles were different between two spills, this resulted in local hot spots between columns of spots. The actual position of spill change varies randomly during measurement, which led to a random occurrence of hot spot within the detector's sensitive volume and a fluctuating dose measurement. This is the first report of a dose fluctuation greater than 5% in absolute dosimetry measurement with a uniform scanned field and the cause of the fluctuation has been conclusively determined. It is important to choose the MU and scanning pattern carefully to avoid spill change happening when the spot delivery is near the detector.

Integrating petrophysical, geological and geomechanical modelling to assess stress states, overpressure development and compartmentalisation adjacent to a salt wall, gulf of Mexico

Multi-well pressure data from the Magnolia Field, located on a flank of the salt-bounded Titan passive mini-basin in the Garden Banks area of the continental slope of the Gulf of Mexico, indicate remarkably high overpressures that vary, at similar depths, by up to 10 MPa between sand bodies 1 km apart. In the present paper, we integrate geological and geophysical analysis with 2D forward hydro-mechanical evolutionary modelling to assess the contribution of both disequilibrium compaction and diapir-related tectonic loading to the observed overpressure and to understand controls on pressure compartmentalisation. The 2D finite element evolutionary model captured the sedimentation of isolated sand channels bounded by mud-dominated sediments close to a rising salt wall which led to tectonic loading on sediments. Comparison of results from the 2D and 1D models shows that disequilibrium compaction can explain most of the overpressure as a result of very rapid deposition of mainly mud-rich, low permeability sediments; tectonic loading contributes around 7% of the observed overpressure. The models also show that linked to the high sedimentation rates, small variations in the permeability and connectivity of the mud-rich sections that bound the channel sands result in highly compartmentalised pressure distributions in adjacent sand bodies.

An Intra-Tissue Radiometry Microprobe for Measuring Radiance In Situ in Living Tissue.

Organisms appear opaque largely because their outer tissue layers are strongly scattering to incident light; strongly absorbing pigments, such as blood, typically have narrow absorbances, such that the mean free path of light outside the absorbance peaks can be quite long. As people cannot see through tissue, they generally imagine that tissues like the brain, fat, and bone contain little or no light. However, photoresponsive opsin proteins are expressed within many of these tissues, and their functions are poorly understood. Radiance internal to tissue is also important for understanding photosynthesis. For example, giant clams are strongly absorbing yet maintain a dense population of algae deep in the tissue. Light propagation through systems like sediments and biofilms can be complex, and these communities can be major contributors to ecosystem productivity. Therefore, a method for constructing optical micro-probes for measuring scalar irradiance (photon flux intersecting a point) and downwelling irradiance (photon flux crossing a plane perpendicularly) to better understand these phenomena inside living tissue has been developed. This technique is also tractable in field laboratories. These micro-probes are made from heat-pulled optical fibers that are then secured in pulled glass pipettes. To change the angular acceptance of the probe, a 10-100 µm sized sphere of UV-curable epoxy mixed with titanium dioxide is then secured to the end of a pulled, trimmed fiber. The probe is inserted into living tissue, and its position is controlled using a micromanipulator. These probes are capable of measuring in situ tissue radiance at spatial resolutions of 10-100 µm or on the scale of single cells. These probes were used to characterize the light reaching the adipose and brain cells 4 mm below the skin of a living mouse and to characterize the light reaching similar depths within living algae-rich giant clam tissue.

Immediate Implant Placement With or Without Immediate Provisionalization in the Maxillary Esthetic Zone: A Systematic Review and Meta-analysis.

To determine whether immediate implant placement and loading renders different outcomes from delayed loading with respect to midfacial mucosal level in the maxillary esthetic area. A literature search was conducted in four electronic databases (PubMed, Web of Science, Embase, and Cochrane), identifying eligible clinical studies published prior to December 2021. Only randomized controlled trials (RCTs) comparing immediate implant placement with or without immediate loading in the maxillary esthetic zone with a mean follow-up of at least 12 months were selected for qualitative analysis and meta-analysis. The Cochrane Risk of Bias tool was adopted to assess the quality of the evidence. The heterogeneity between the pooled literature was analyzed through the chi-square test (P < .05) and quantified by the I2 index. A mixed-effects model was applied if it appeared that there was noteworthy heterogeneity; otherwise, a random-effects model was chosen. For continuous outcomes, the estimate of relative effect was presented to display the standardized mean differences (SMDs) and 95% CIs. For dichotomous variables, the Mantel-Haenszel statistical method was applied with effect sizes expressed as risk ratios (RRs) and 95% CIs. This study is registered on PROSPERO with number CRD42017078611. Out of 5,553 records, 8 RCTs were involved, providing data for 324 immediately placed implants (immediate implants subjected to immediate loading [IPIL]: 163; immediate implants subjected to delayed loading [IPDL]: 161) that had been in function within 12 to 60 months. Meta-analyses revealed significantly lower midfacial mucosal level changes for IPIL compared with IPDL, pointing to 0.48 mm (95% CI: -0.84 to -0.12; P = .01), as well as more significant papillary recession after IPDL (SMD -0.16; 95% CI: -0.31 to 0.00; P = .04). The differences regarding implant survival and marginal bone loss between the two loading groups showed no statistical significance. The result of metaanalyses revealed similar plaque score (SMD 0.03; 95% CI: -0.22 to 0.29; P = .79) and probing depth (SMD -0.09; 95% CI: -0.23 to 0.05; P = .21) for IPIL and IPDL. On the other hand, IPIL induced a trend toward more bleeding on probing (SMD 0.22; 95% CI: 0.01 to 0.42; P = .04) and less change in facial ridge dimension (SMD 0.94; 95% CI: -1.49 to -0.39; P < .01). After a follow-up ranging from 12 to 60 months, midfacial mucosa level change was 0.48 mm lower following IPIL compared with IPDL. Immediate implant placement and loading is conducive to the preservation of physiologic soft and hard tissue architecture, appearing to offer considerable benefits in the anterior zone. In summary, IPIL should be considered in the esthetic zone if the primary implant stability permits. Int J Oral Maxillofac Implants 2023;38:422-434. doi: 10.11607/jomi.10112.

Cortical layering disrupts multi-electrode current steering

Objective. Blindness affects approximately 40 million people worldwide and has inspired the development of cortical visual prostheses for restoring sight. Cortical visual prostheses electrically stimulate neurons of the visual cortex to artificially evoke visual percepts. Of the 6 layers of the visual cortex, layer 4 contains neurons that are likely to evoke a visual percept. Intracortical prostheses therefore aim to target layer 4; however, this can be difficult due to cortical curvature, inter-subject cortical variability, blindness-induced anatomical changes in cortex, and electrode placement variations. We investigated the feasibility of using current steering to stimulate specific cortical layers between electrodes in the laminar column. Approach. We explored whether the multiunit neural activity peak can be manipulated between two simultaneously stimulating electrodes in different layers of the cortical column. A 64-channel, 4-shank electrode array was implanted into the visual cortex of Sprague–Dawley rats (n = 7) orthogonal to the cortical surface. A remote return electrode was positioned over the frontal cortex in the same hemisphere. Charge was supplied to two stimulating electrodes along a single shank. Differing ratios of charge (100:0, 75:25, 50:50) and separation distances (300–500 μm) were tested. Results. Current steering across the cortical layers did not result in a consistent shift of the neural activity peak. Both single-electrode and dual-electrode stimulation induced activity throughout the cortical column. This contrasts observations that current steering evoked a controllable peak of neural activity between electrodes implanted at similar cortical depths. However, dual-electrode stimulation across the layers did reduce the stimulation threshold at each site compared to single-electrode stimulation. Significance. Multi-electrode stimulation is not suitable for targeted activation of layers using current steering. However, it can be used to reduce activation thresholds at adjacent electrodes within a given cortical layer. This may be applied to reduce the stimulation side effects of neural prostheses, such as seizures.

Crustal Structure and Geothermal Mechanism of the Gonghe-Guide Basin Based on EIGEN-6C4 Satellite Gravity and Aeromagnetic Data

The Gonghe-Guide Basin is situated in the northeastern edge of the Tibetan Plateau, one of China’s main targets for geothermal research and exploitation. We present a new crustal structure of the entire basin by using EIGEN-6C4 satellite gravity and aeromagnetic data aimed to further recognize the geothermal mechanisms. The data are processed using the wavelet multi-scale decomposition method and the iterative compact depth from extreme points imaging method. The gravity inversion results reveal distinct low-density regions in the middle-upper crust at 15–35 km depth, which is most likely caused by partial melting. The magnetic inversion results show negative or no magnetism within a similar depth range. But at shallow depths of the same horizontal positions, there is high positive magnetism, which can be interpreted as granite. The results correspond well with the magnetotelluric and seismic results and can be an effective supplement. To confirm and validate this conclusion, a 2D geological model of a profile from a typical area is created to show the detailed tectonic. Based on the new crustal structure results, the suggested geothermal target is the low/negative density corresponding to low/negative magnetism located at deep depths and high/positive magnetism located at shallow depths. Then we established a geological conceptual model to illustrate this process. This indicates that tectonic movement is taking place in the deep part of the earth in the Gonghe-Guide Basin. The research on the geological structure and geothermal heat source mechanism in the Gonghe-Guide Basin can provide a primary reference for research on geothermal resources in other areas with similar geological structures.

Ultisols with Unique Soil Properties and their Implications in Carbon Enhancement Strategies for Indian Tropical Soils

Million years old Ultisols, developed as an end stage of advance soil weathering on base-poor rock systems under forest and plantation crops of the Indian sub-continent, are enriched with organic carbon (OC). Despite their remarkable acid chemical reaction, they show an upward increase in extractable bases (EB) and base saturation (BS) in the pedon, and on some occasion BS &gt; 35% in surface horizons. Recent research suggests that the litter falls from forest species provide bases on soil surface, which causes similar depth distribution of EB and BS in Andisols of Nilgiri Hills of humid tropical southern India, developed on pre-weathered lateritic materials consisting primarily of Fe and Al oxides/ hydroxides. Under similar humid tropical (HT) climate in protected rain forest, million years old OC rich soils of Andaman and Nicobar Islands, developed on base-poor rock systems, have similar chemical and clay mineralogical properties of Ultisols except however their EB and BS, which are more than 10% and much above 50%, respectively and therefore, they are acidic Alfisols. Formation of Alfisols on the Island is a unique example on the formidable role of vegetation in soil formation, suggesting that if inland Ultisols are kept under natural protected forest ecosystem, they may phase towards Alfisols thereby facilitating OC sequestration and perform other ecosystem functions. The preservation of natural or semi-natural ecosystems is thus essential to raise the OC stocks of soils, which would help to gain various ecological benefits.

Nano-Indentation to Determine Mechanical Properties of Intraocular Lenses: Evaluating Penetration Depth, Material Stiffness, and Elastic Moduli.

Intraocular lenses (IOL) should remain in the eye for life after implantation into the capsular bag during cataract surgery. The material must meet various requirements. It is crucial that the material has the best biocompatibility, and it should be flexible and soft for best possible implantation process but also sufficiently stable and stiff for good centering in the eye and posterior capsule opacification prevention. In this laboratory experiment, we used nano-indentation for the mechanical assessment of three hydrophobic acrylic (A, B, C), three hydrophilic acrylic (D, E, F), and one silicone (G) intraocular lens. We wanted to determine whether some react more sensitively to touching/handling than others. The indentation elastic modulus and the creep were obtained from the force displacement curve. For measuring penetration depth and testing of possible damage to the intraocular lenses, the samples were measured at room temperature. A 200-µm-diameter ruby spherical tipped indenter was used for all the tests. Indentations were made to three different maximum loads, namely 5mN (milli Newton), 15mN, and 30mN and repeated three times. The lowest penetration depth (12µm) was observed with IOL B. However, IOL A, D, and F showed similar low penetration depths (20, 18, and 23µm, respectively). Lenses C and E showed slightly higher penetration depths of 36 and 39µm, respectively. The silicone lens (G) showed the greatest penetration depth of 54.6µm at a maximum load of 5mN. With higher maximal loads (15 and 30mN) the penetration depth increased significantly. Lens C, however, showed the same results at both 15 and 30mN with no increase of penetration depth. This seems to fit well with the material and manufacturing process of the lens (lathe-cut). During the holding time of 30s at constant force all six acrylic lenses showed a significant increase of the creep (CIT 21-43%). Lens G showed the smallest creep with 14%. The mean indentation modulus (EIT) values ranged from 1 to 37MPa. IOL B had the largest EIT of 37MPa, which could be caused by the low water content. It was found that results correlate very well with the water content of the material in the first place. The manufacturing process (molded versus lathe-cut) seems to play another important role. Since all included acrylic lenses are very similar, it was not surprising that the measured differences are marginal. Even though hydrophobic materials with lower water content showed higher relative stiffness, penetration and defects can also occur with these. The surgeon and scrub nurse should always be aware that macroscopic changes are difficult to detect but that defects could theoretically lead to clinical effects. The principle of not touching the center of the IOL optic at any time should be taken seriously.

New Accelerated Corrosion Test Method Simulating Atmospheric Corrosion of Complex Phase Steel Combining Cyclic Corrosion Test and Electrochemically Accelerated Corrosion Test.

The automobile industry commonly uses cyclic corrosion tests (CCTs) to evaluate the durability of materials. However, the extended evaluation period required by CCTs can pose challenges in this fast-paced industry. To address this issue, a new approach that combines a CCT with an electrochemically accelerated corrosion test has been explored, to shorten the evaluation period. This method involves the formation of a corrosion product layer through a CCT, which leads to localized corrosion, followed by applying an electrochemically accelerated corrosion test using an agar gel electrolyte to preserve the corrosion product layer as much as possible. The results indicate that this approach can achieve comparable localized corrosion resistance, with similar localized corrosion area ratios and maximum localized corrosion depths to those obtained through a conventional CCT in half the time.

Nonsurgical cleaning potential of deep-threaded implants and titanium particle release: A novel in vitro tissue model.

To measure the efficiency of three cleaning modalities on two implant designs with similar diameters but different thread depths as well as the presence of titanium particles. Sixty dyed implants (30 × 4.8 apically tapered (ATAP) and 30 × 5.0 fully tapered (FTAP)) were fixed in plastic models. The horizontal bone defects were surrounded with porcine soft tissue. Three instrumentation modalities were used to clean for 150 s: Curette (CUR), ultrasonic scaler (US), and air powder waterjet device (APWJ) with erythritol powder. Afterward, implants were photographed and scanning electron microscopic (SEM) images were taken. Titanium in the soft tissues was quantified in dissolved samples and histologically confirmed. For ATAP and FTAP implants, the percentage of the cleaned surface was 26.4 ± 3.0 and 17.1 ± 2.4% for CUR, 33.7 ± 3.8% and 28.1 ± 2.3% for US, and 45.5 ± 4.1% and 24.7 ± 3.8% for APWJ, respectively. SEM images showed significant implant surface changes, especially after instrumentation with CUR and US, whereas APWJ had little to no effect. Most titanium residues were found after cleaning ATAP implants with CUR (152.0 ± 75.5), followed by US (89.5 ± 73.8) and APWJ (0.3 ± 0.8). For the FTAP implants, respective values accounted for 129.5 ± 58.6 μg and 67.0 ± 14.4 μg for CUR and US, respectively. No titanium residues were detected on ATAP with APWJ. Based on in vitro data, erythritol-powered APWJ still appears to be the most efficient and gentle cleaning method. All three instruments, however, were found to have unprocessed areas depending on different implant designs, hence, clinical relevance for non-surgical approaches remains challenging and warrants further improvement.

Tissue-Like 3D Standard and Protocols for Microscope Quality Management.

This article outlines a global study conducted by the Association of Biomedical Resource Facilities (ABRF) Light Microscopy Research Group (LMRG). The results present a novel 3D tissue-like biologically relevant standard sample that is affordable and straightforward to prepare. Detailed sample preparation, instrument-specific image acquisition protocols and image analysis methods are presented and made available to the community. The standard consists of sub-resolution and large well characterized relative intensity fluorescence microspheres embedded in a 120 µm thick 3D gel with a refractive index of 1.365. The standard allows the evaluation of several properties as a function of depth. These include the following: 1) microscope resolution with automated analysis of the point-spread function (PSF), 2) automated signal-to-noise ratio analysis, 3) calibration and correction of fluorescence intensity loss, and 4) quantitative relative intensity. Results demonstrate expected refractive index mismatch dependent losses in intensity and resolution with depth, but the relative intensities of different objects at similar depths are maintained. This is a robust standard showing reproducible results across laboratories, microscope manufacturers and objective lens types (e.g., magnification, immersion medium). Thus, these tools will be valuable for the global community to benchmark fluorescence microscopes and will contribute to improved scientific rigor and reproducibility.

Development of two new sets of PCR primers for eDNA metabarcoding of brittle stars (Echinodermata, Ophiuroidea)

Brittle stars (class Ophiuroidea) are marine invertebrates comprising approximately 2,100 extant species, and are considered to constitute the most diverse taxon of the phylum Echinodermata. As a non-invasive method for monitoring biodiversity, we developed two new sets of PCR primers for metabarcoding environmental DNA (eDNA) from brittle stars. The new primer sets were designed to amplify 2 short regions of the mitochondrial 16S rRNA gene, comprising a conserved region (111–115 bp, 112 bp on average; named “16SOph1”) and a hyper-variable region (180–195 bp, 185 bp on average; named “16SOph2”) displaying interspecific variation. The performance of the primers was tested using eDNA obtained from two sources: a) rearing water of an 2.5 or 170 L aquarium tanks containing 15 brittle star species and b) from natural seawater collected around Misaki, the Pacific coast of central Japan, at depths ranging from shallow (2 m) to deep (&amp;gt; 200 m) sea. To build a reference library, we obtained 16S rRNA sequences of brittle star specimens collected from around Misaki and from similar depths in Japan, and sequences registered in International Nucleotide Sequence Database Collaboration. As a result of comparison of the obtained eDNA sequences with the reference library 37 (including cryptic species) and 26 brittle star species were detected with certain identities by 16SOph1 and 16SOph2 analyses, respectively. In shallow water, the number of species and reads other than the brittle stars detected with 16SOph1 was less than 10% of the total number. On the other hand, the number of brittle star species and reads detected with 16SOph2 was less than half of the total number, and the number of detected non-brittle star metazoan species ranged from 20 to 46 species across 6 to 8 phyla (only the reads at the “Tank” were less than 0.001%). The number of non-brittle star species and reads at 80 m was less than 10% with both of the primer sets. These findings suggest that 16SOph1 is specific to the brittle star and 16SOph2 is suitable for a variety of marine metazoans. It appears, however, that further optimization of primer sequences would still be necessary to avoid possible PCR dropouts from eDNA extracts. Moreover, a detailed elucidation of the brittle star fauna in the examined area, and the accurate identification of brittle star species in the current DNA databank is required.

Summer distribution and habitat preference of beluga whale social groups in the Eastern Beaufort Sea

In social animals, group composition can cause variations in individual needs that can influence responses to habitat trade-offs, such as predator exposure or foraging opportunities. The Eastern Beaufort Sea beluga whales ( Delphinapterus leucas (Pallas, 1776)) form different group types and cover multiple habitat types in summer. This study compares the habitat preference of three beluga social group types: (1) individual belugas, (2) groups of adults, and (3) groups with at least one calf. Observations were collected during aerial surveys in July and August 2019. For each month, beluga distribution was analyzed with hierarchical generalized additive models, as a function of group type and four covariates: sea surface temperature, bathymetry, slope, and distance to the coastline. Group type, water temperature, and bathymetric features best explained beluga distribution. In July, groups of adults preferred the continental shelf, whereas individual belugas and groups with calves preferred the continental slope. In August, groups of adults and groups with calves were found in Amundsen Gulf at similar depths. For both months, individual belugas associated more with deeper and colder areas. The preferences often corresponded to previously published distributions of the beluga's main prey species, suggesting that foraging opportunities and size-related energy requirements strongly influence habitat use.

Relación entre vulcanismo dacítico monogenético y poligenético. Caso de estudio del domo Tapias (&lt;95 ka) y volcán Cerro Machín (&lt;50 ka), Colombia

The Tapias lava dome is located ~5 km SE of the explosive, Cerro Machín polygenetic volcano, both located on the Colombian Central Cordillera. The edifices have been interpreted as generated by the same magmatic system; however, the genetic and temporal relations between both edifices have not been established. In this work, the Tapias dome is studied using petrographic characterizations, mineral-, whole-rock- and isotopic chemistry, geothermobarometric calculations, and a K/Ar radiogenic age, and subsequently it is explored the relationship with the Cerro Machín. The rocks from Tapias dome are porphyritic with phenocrysts of plagioclase (An28-48), amphibole (tschermakite and magnesiohastingsite), biotite, quartz, and Fe-Ti oxides, embedded in a glassy groundmass. Petrographically, two types of amphibole crystals were recognized: type I, which is homogeneous, and type II, which displays different rims. The composition of Tapias is dacitic (SiO2: 66.59 wt.%) with calc-alkaline affinity. Our geothermobarometric calculations indicate that type I amphibole crystallized at 871-874°C, between 10.2 and 10.4 km depth. The core of the type II amphibole crystallized at 852-920°C, between 8.5 and 12.3 km depth, while its rim did it at higher temperatures (880-973°C), but at similar depths (9.1-11.8 km). The K/Ar radiogenic age obtained for the groundmass shows an emplacement age not older than 95 ± 0.05 ka. When comparing the results to the Cerro Machín, it is noted that the mineral and compositional characteristics are nearly identical. These results suggest that indeed both volcanoes share the same magmatic system and are fed by magma hosted between ~9 and ~12 km depth. Moreover, it is proposed that the vent location of both edifices, as well as the time gap between the eruption at Tapias and the beginning of the activity at the Cerro Machín (~50 ka), are the result of crustal deformation caused by the interaction between the Otú-Pericos and Ibagué faults.

Body size, depth of occurrence, and local oceanography shape trophic structure in a diverse deep-pelagic micronekton assemblage

The Gulf of Mexico’s (GOM) deep-pelagic realm is one of the planet’s most speciose pelagic ecoregions, but detailed knowledge of ecosystem structure and function is lacking. Understanding trophic structure is critical to understanding ecosystem dynamics as trophic interactions regulate the flow of energy through ecosystems and influence the resilience of ecosystems to disturbance. Using novel stable isotope (SIA) data and historical stomach content (SCA) data, we examined deep-pelagic trophic structure using 58 species of micronekton from the GOM that encompassed a variety of migratory behaviors, depth distributions, and trophic strategies. We identified major trophic groupings, explored the extent that differences in diet, body size, vertical migration, and presence of a mesoscale feature (Loop Current) explained micronekton isotopic variation and estimated species-specific trophic positions. Cluster analysis of SIA data identified four trophic groups, although species were not strictly clustered by diet. Specifically, non-migratory zooplanktivores with elevated δ15N values were grouped with vertically migrating piscivores, suggesting some non-migratory species could be feeding within food chains with elevated isotopic baselines. The mean δ13C values of species encompassed a narrow range from −21.6 ‰ to −18.1 ‰, with variation in δ13C values of vertically migrating species explained by a positive relationship with body size and higher δ13C values in Loop Current water. In contrast, variation in δ13C values of non-migrators was primarily explained by elevated values in deeper-dwelling species and in larger species. The mean δ15N values of species ranged between 5.0 ‰ and 11.5 ‰, with variation in δ15N values of vertical migrators explained by a positive relationship with body size and lower δ15N values in Loop Current water. Variation in the δ15N values of non-migrators was largely explained by elevated δ15N values in deeper-dwelling species and in larger-bodied species. Trophic position (TP) estimations for the assemblage ranged between 2.6 and 4.9. The elevated δ15N values in non-migratory species led to higher TP estimates relative to estimates derived from stomach content data, but agreement between TP estimates using SIA and SCA was high for vertically migrating taxa. This discrepancy may be a factor of vertical migrating species having a more similar feeding depth than non-migrators. Our results provide important insight into the trophic organization of low-latitude oligotrophic ecosystems and demonstrate that trophic variation within micronekton assemblages is primarily driven by differences in body size, location in the water column and position relative to salient oceanographic features.

Automated real-time formation evaluation from cuttings and drilling data analysis: State of the art

Traditional formation evaluation via laboratory testing and wireline logging of horizontal wells and deep formations face challenges due to several reasons and lead to uncertain results. Real-time cuttings and drilling data analysis of horizontal wells is an actively developing alternative approach to formation evaluation that can overcome several challenges faced by laboratory testing and wireline logging in providing improved estimates of formation parameters relevant to reservoir and completion quality. This study presents a state-of-the-art review of the latest methods and technologies in drill cuttings analysis to enable real-time characterization of the entire suite of formation properties, including chemical composition, densities and porosity, permeability, lithology, geomechanical properties, and characterization of fracture patterns. Specifically, the methods/techniques that enable characterizing drill cuttings in real-time and critically reviewed in this study include Raman spectroscopy for chemical composition, nuclear magnetic resonance for densities and porosity, liquid pressure pulse for permeability, deep learning for rock classification, 7 different methods for geomechanical properties, and mud loss signatures for characterization of fracture patterns. Benchmark comparison of drill cuttings analysis with the measurements from the core samples at similar depths is also reviewed. Key learnings are provided in 4 areas: to address the uncertainties in estimates of specific parameters affected by physical deformations due to drill bits, minimum cutting size for reliable nuclear magnetic resonance data, sweet spot identification, and power and network considerations for real-time analysis, respectively. Cited as: Singh, H., Li, C., Cheng, P., Wang, X., Hao, G., Liu, Q. Automated real-time formation evaluation from cuttings and drilling data analysis: State of the art. Advances in Geo-Energy Research, 2023, 8(1): 19-36. https://doi.org/10.46690/ager.2023.04.03

Lake volume and potential hazards of moraine-dammed glacial lakes – a case study of Bienong Co, southeastern Tibetan Plateau

Abstract. The existence of glacial lakes in the southeastern Tibetan Plateau (SETP) is a potential hazard to downstream regions, as the outburst of such lakes has the potential to result in disastrous glacial lake outburst floods (GLOFs). In the present study, we conducted a comprehensive investigation of Bienong Co, a moraine-dammed glacial lake in the SETP. First, the lake basin morphology was determined, and the lake volume was estimated, showing that the maximum lake depth is ∼181 m and the lake volume is ∼102.3×106 m3. These scenarios included the possibility of GLOFs being triggered by ice avalanches (Scenarios A1–3) from the mother glacier or by landslides from the lateral moraines (Scenarios B1–3 and C1–3). Avalanche volumes of the nine trigger scenarios were obtained from the Rapid Mass Movement Simulation (RAMMS) modeling results. Next, the Basic Simulation Environment for Computation of Environmental Flow and Natural Hazard Simulation (BASEMENT) model was used to simulate the generation and propagation of the avalanche-induced displacement waves in the lake. With the model, the overtopping flows and erosion on the moraine dam and the subsequent downstream floods were also simulated. The results indicate that the ice avalanche scenario may cause the largest mass volume entering the lake, resulting in a displacement wave up to 25.2 m in amplitude (Scenario A3) near the moraine dam. Landslide scenarios with smaller volumes entering the lake result in smaller displacement waves. Scenarios A1, A2, and A3 result in released water volumes from the lake of 24.1×106, 25.3×106, and 26.4×106 m3, respectively. Corresponding peak discharges at the moraine dam are 4996, 7817, and 13 078 m3 s−1, respectively. These high discharges cause erosion of the moraine dam, resulting in breach widths of 295, 339, and 368 m, respectively, with the generally similar breach depth of approximately 19 m. In landslide scenarios, only overtopping flows generated by Scenarios B3 and C3 cause erosion on the moraine dam, with breach depths of 6.5 and 7.9 m and breach widths of 153 and 169 m, respectively. According to our simulations, GLOFs generated by Scenarios A1–3 all flow through 18 settlements downstream in 20 h, threatening more than half of them. Both Scenarios B3 and C3 produce GLOFs that flow through the first eight settlements downstream in 20 h and have a relatively small impact on them. Comparisons of the area, depth, and volume of glacial lakes for which the bathymetry data are available show that Bienong Co is the deepest known glacial lake with the same surface area on the Tibetan Plateau. This study could provide a new insight into moraine-dammed glacial lakes in the SETP and be a valuable reference for GLOF disaster prevention for the local government.

Young Radio Sources Expanding in Gas-Rich ISM: Using Cold Molecular Gas to Trace Their Impact

We present an overview of the results obtained from the study of the resolved distribution of molecular gas around eight young (≲106yr), peaked-spectrum radio galaxies. Tracing the distribution and kinematics of the gas around these radio sources allows us to trace the interplay between the jets and the surrounding medium. For three of these sources, we present new CO(1-0) observations, obtained with the Northern Extended Millimeter Array (NOEMA) with arcsecond resolution. In two of these targets, we also detected CN lines, both in emission and absorption. Combining the new observations with already published data, we discuss the main results obtained. Although we found that a large fraction of the cold molecular gas was distributed in disc-like rotating structures, in the vast majority of the sources, high turbulence and deviations from purely quiescent gas (including outflows) were observed in the region co-spatial with the radio continuum emission. This suggests the presence of an interaction between radio plasma and cold molecular gas. In particular, we found that newly born and young radio jets, even those with low power i.e., Pjet &lt; 1045 erg s−1), are able to drive massive outflows of cold, molecular gas. The outflows are, however, limited to the sub-kpc regions and likely short lived. On larger scales (a few kpc), we observed cases where the molecular gas appears to avoid the radio lobes and, instead, wraps around them. The results suggest the presence of an evolutionary sequence, which is consistent with previous simulations, where the type of impact of the radio plasma changes as the jet expands, going from a direct jet-cloud interaction able to drive gas outflows on sub-kpc scales to a more gentle pushing aside of the gas, increasing its turbulence and likely limiting its cooling on kpc scales. This effect can be mediated by the cocoon of shocked gas inflated by the jet–cloud interactions. Building larger samples of young and evolved radio sources for observation at a similar depth and spatial resolution to test this scenario is now needed and may be possible thanks to more data becoming available in the growing public archives.

Inhomogeneous Enrichment of Radioactive Nuclei in the Galaxy: Deposition of Live 53Mn, 60Fe, 182Hf, and 244Pu into Deep-sea Archives. Surfing the Wave?

While modeling the galactic chemical evolution (GCE) of stable elements provides insights to the formation history of the Galaxy and the relative contributions of nucleosynthesis sites, modeling the evolution of short-lived radioisotopes (SLRs) can provide supplementary timing information on recent nucleosynthesis. To study the evolution of SLRs, we need to understand their spatial distribution. Using a three-dimensional GCE model, we investigated the evolution of four SLRs: 53Mn, 60Fe, 182Hf, and 244Pu with the aim of explaining detections of recent (within the last ≈1–20 Myr) deposition of live 53Mn, 60Fe, and 244Pu of extrasolar origin into deep-sea reservoirs. We find that core-collapse supernovae are the dominant propagation mechanism of SLRs in the Galaxy. This results in the simultaneous arrival of these four SLRs on Earth, although they could have been produced in different astrophysical sites, which can explain why live extrasolar 53Mn, 60Fe, and 244Pu are found within the same, or similar, layers of deep-sea sediments. We predict that 182Hf should also be found in such sediments at similar depths.

Can a Computational Model Predict the Effect of Lesion Location on Cam-type Hip Impingement?

The Warwick consensus defined femoroacetabular impingement syndrome as a motion-related clinical disorder of the hip with a triad of symptoms, clinical signs, and imaging findings representing symptomatic premature contact between the proximal femur and acetabulum. Several factors appear to cause labral and cartilage damage, including joint shape and orientation and patient activities. There is a lack of tools to predict impingement patterns in a patient across activities. Current computational modeling tools either measure pure ROM of the joint or include complexity that reduces reliability and increases time to achieve a solution. The purpose of this study was to examine the efficacy of a low computational cost approach to combining cam-type hip shape and multiple hip motions for predicting impingement. Specifically, we sought to determine (1) the potential to distinguish impingement in individual hip shapes by analyzing the difference between a cam lesion at the anterior femoral neck and one located at the superior femoral neck; (2) sensitivity to three aspects of hip alignment, namely femoral neck-shaft angle, femoral version angle, and pelvic tilt; and (3) the difference in impingement measures between the individual activities in our hip motion dataset. A model of the shape and alignment of a cam-type impinging hip was created and used to describe two locations of a cam lesion on the femoral head-neck junction (superior and anterior) based on joint shape information available in prior studies. Sensitivity to hip alignment was assessed by varying three aspects from a baseline (typical alignment described in prior studies), namely, femoral neck-shaft angle, femoral version, and pelvic tilt. Hip movements were selected from an existing database of 18 volunteers performing 13 activities (10 male, eight female; mean age 44 ± 19 years). A subset was selected to maximize variation in the range of joint angles and maintain a consistent number of people performing each activity, which resulted in nine people per activity, including at least three of each sex. Activities included pivoting during walking, squatting, and golf swing. All selected hip motion cases were applied to each hip shape model. For the first part of the study, the number of motion cases in which impingement was predicted was recorded. Quantitative analyses of the depth of penetration of the cam lesion into the acetabular socket and qualitative observations of impingement location were made for each lesion location (anterior and superior). In the second part of the study, in which we aimed to test the sensitivity of the findings to hip joint orientation, full analysis of both cam lesion locations was repeated for three modified joint orientations. Finally, the results from the first part of the analysis were divided by activity to understand how the composition of the activity dataset affected the results. The two locations of cam lesion generated impingement in a different percentage of motion cases (anterior cam: 56% of motion cases; superior cam: 13% of motion cases) and different areas of impingement in the acetabulum, but there were qualitatively similar penetration depths (anterior cam: 6.8° ± 5.4°; superior cam: 7.9° ± 5.8°). The most substantial effects of changing the joint orientation were a lower femoral version angle for the anterior cam, which increased the percentage of motion cases generating impingement to 67%, and lower neck-shaft angle for the superior cam, which increased the percentage of motion cases generating impingement to 37%. Flexion-dominated activities (for example, squatting) only generated impingement with the anterior cam. The superior cam generated impingement during activities with high internal-external rotation of the joint (for example, the golf swing). This work demonstrated the capability of a simple, rapid computational tool to assess impingement of a specific cam-type hip shape (under 5 minutes for more than 100 motion cases). To our knowledge, this study is the first to do so for a large set of motion cases representing a range of activities affecting the hip, and could be used in planning surgical bone removal. The results of this study imply that patients with femoroacetabular impingement syndrome with cam lesions on the superior femoral head-neck junction may experience impinging during motions that are not strongly represented by current physical diagnostic tests. The use of this tool for surgical planning will require streamlined patient-specific hip shape extraction from imaging, model sensitivity testing, evaluation of the hip activity database, and validation of impingement predictions at an individual patient level.