Exact Depth Research Articles

Correlation of prosthesis position on mid-term pacing burden in patients with new permanent pacemaker after TAVI

Abstract Background Prior studies suggest a strong correlation of the final prosthesis position on the occurrence of new conduction disturbances resulting in permanent pacemaker (PPM) implantation after transcatheter aortic valve implantation (TAVI). A high burden right ventricular pacing (PPM stimulation rate of > 20 %) is associated with poor long-term outcomes. So far, data about predictors influencing the PPM stimulation rate after TAVI are scarce. Purpose Thus, the purpose of this study was to evaluate the influence of the three-dimensional transcatheter heart valve (THV) position, as well as device landing zone characteristics or peri-/post-procedural factors on the stimulation rate in patients with new implanted PPM as TAVI complication. Materials: We evaluated the final THV position of 387 patients (106 with self-expanding Evolut R THV, 281 with balloon-expandable Sapien 3 THV) using fusion imaging of pre- and post-TAVI computed tomography angiography (CTA) to obtain a three-dimensional reconstruction of the THV within the native annulus region. The length of the THV above and below the native annulus was measured within the fused images to assess the implantation depth. PPM stimulation rates were examined pre-discharge and after 3 months. Patient’s clinical long-term outcome was evaluated over 5 years via standardized questionnaire as well as contacting general practitioners. Results Out of the 387 patients 112 (29%) received a new PPM pre-discharge after TAVI between 2014 and 2022. They were grouped into patients with stimulations rate below and above 20%. A stimulation rate > 20% in the PPM control before discharge and after three months was detected in 69 % and 67 % of them, respectively. Using uni- and multivariate logistic regression analysis, only new occurred third degree atrioventricular blocks (p=0.007) was identified as predictor for high burden right ventricular pacing after PPM-implantation as well as after 3 months. The implantation depth of the THV showed no influence on the PPM stimulation rate – neither the mean value nor the exact implantation depth adjacent the left, right and non-coronary cusp (P=0.455, P=0.108 and P=0.932, respectively). There were no significant differences regarding MACE between both groups during long-term follow-up; only the degree of dyspnea 5 years after TAVI was significantly higher in patients with a stimulation rate > 20% (p=0.01). Conclusion We detected no correlation of the exact three-dimensional THV position on mid-term pacing burden in 112 patients implanted with a new PPM after TAVI using CTA fusion imaging. Only a new occurred third degree atrioventricular block was a predictor for a high burden right ventricular pacing (stimulation rate >20%). These results provide important insights into which patients actually require PPM implantation after TAVI.

Potholes Detection in Doppler Radar Signal’s Power Spectral Density using Decision Tree

Potholes are defects on the surface of roads, streets, or pavements brought on by depressions or holes, which are hazardous for vehicles and pedestrians, whether small divots or huge craters. Various methods have been explored to improve the accuracy of potholes detection. Existing approaches have advantages and disadvantages. This paper presents the proposed method of pothole detection utilising Doppler Radar signal's Power Spectrum Density (PSD) together with the Decision Tree classification algorithm. While continuous waveform (CW) radar is able to identify moving targets, it cannot localise the exact depth of the reflector, which is the prominent characteristic of potholes. In addition, the target's reflected signal is likely to be masked by nearby harmonics. Since the radar is moving despite the target of interest, mounting it on a moving vehicle offers a different perspective. This paper explores the potential of Doppler radar's signal for pothole detection while comparing two Machine Learning (ML) techniques. A commercially over-the-shelf (COTS) K-LC2 Doppler radar was employed to acquire pothole and non-pothole raw datasets. Doppler signal was hardly distinguished between pothole and non-pothole, either in the time or frequency domain. Hence, Doppler signals were converted to power spectral density (PSD), and PSD's features were extracted. Extracted features were applied with the coarse Decision Tree (DT) and K-Nearest Neighbours (KNN) classification algorithms. The result exhibits a better accuracy of 91.2% for 80:20 distribution by using the Decision Tree.

Estimation of top depth to underground targets of Karous-Hjelt and Fraser filtering of VLF-EM measurements: The Thumb's rule approach

Prediction of the exact location and depth of underground targets with the very low-frequency electromagnetic (VLF-EM) technique is one of the most important and difficult tasks in geophysical investigations. This study examined and compared the conventional 2D KIFFILT inversion pseudo-section and the use of Thumb's rule technique in the Fraser filter plot to estimate the top depth of underground targets. The VLF-EM measurement was performed over several empirical buried target models to identify anomalies or geophysical responses corresponding to subsurface targets. The Karous-Hjelt and Fraser filtering techniques were applied to estimate the depth of the identified anomalies using Thumb's rule and the conventional 2D KIFFILT inversion. The signal behaviours of the VLF-EM current density pseudo-sections and the application of Thumb's rule effectiveness in delineating empirical buried target models were examined. Thumb's rule shows 65 % accuracy with the actual depth of the empirical buried target models, while the conventional 2D KHFFILT inversion shows 30 % accuracy with the actual depth of burial. Thumb's rule is more effective and precise in predicting the accurate depth of underground targets. The influences of conductive and resistive materials on VLF-EM signals and the challenges of VLF-EM surveys were discussed. Thumb's rule is suggested as a substantial technique for estimating top depth to the underground target where depth estimation is of prime interest due to its large degree of accuracy. In addition, the total depth of the current density distribution was noted to be increased when the distance between measuring points increased. This means that VLF-EM signals with longer wavelengths indicate deeper depth penetration into the ground than signals with shorter wavelengths. The accuracy of Thumb's rule regarding top depth estimation of the anomalies has been successfully tested and validated, which can be used for VLF-EM investigation where accurate depth estimation is required. The VLF-EM technique can be considered reliable for depth estimation using Thumb's rule approach, which applies to a wide range of subsurface investigations.

Detection of shallow underground targets using electrical resistivity tomography and the implications in civil/environmental engineering

Applying the electrical resistivity tomography (ERT) technique in detecting very near-surface targets is quite challenging in geophysical investigation, especially in civil and environmental engineering for adequate planning and designing of structural foundations, contributing to the overall safety and efficiency of construction projects. However, locating the exact position and depth of underground targets such as faults, underground utilities, and contaminants is more challenging. Therefore, this study is aimed at examining the geophysical response of various buried targets and evaluating the ability of ERT to detect buried targets in terms of locations and depths of occurrence in the context of engineering investigation and environmental studies. A laboratory test was conducted on the targets to determine their electrical conductivity and resistivity before burial. The two-dimensional (2D) ERT survey was performed on thirteen targets buried at the site using both Wenner and dipole–dipole (DD) arrays. Both arrays captured the metallic targets with a low electrical resistivity contrast (< 0.1 Ωm) corresponding to the laboratory results. In comparison, the positions of the non-metallic buried targets were found to have a high resistivity contrast greater than 3000 Ωm, matching the laboratory results. The modelled pipes and the car engine block captured by both DD and Wenner arrays on 1.0 m electrode spacing were relatively smeared and poorly resolved in shapes, sizes and geometries, while some were not captured. The electrode spacing of 0.25 m and 0.50 m was explored on undetected targets, which provide a better resolution with sizes and depths compared to 1.0 m spacing but did not produce satisfactory results in some cases. The success and failure of ERT to detect a few targets were discussed alongside the environmental and engineering implications. The effectiveness of both arrays was assessed by their sensitivity in mapping the change in subsurface resistivity values. The DD array shows sensitivity to horizontal variations in resistivity values with low signal. In contrast, the Wenner array shows a good signal strength with a good change in the horizontal and vertical resistivity values. In addition, both arrays show capacity in mapping the geophysical signature of the buried targets and subsurface structures, which has significant application in engineering and environmental investigations.

Impact of roots on the shear strength of root-reinforced soil on slopes

Abstract Tropical countries generally receive high rainfall throughout the year causing high runoff, wet soils and erosion. Undulating terrain from continuing erosion and frequent occurrences of landslides are the features of topographic evolution under such hydrological conditions. Vegetation is the only natural supporting factor that mitigates both erosion and landslides. It contributes to controlling soil erosion and strengthening of the soil by forming a mesh of roots at the surface. The objective of this study is to quantify soil strength on slopes when there is a presence of roots. Undisturbed samples were taken from two different depths of soil. The exact depth and distance varied slightly to avoid large roots and large gravel particles present in the natural environment. Immediately after sampling, the triaxial tests were performed under unconsolidated and undrained conditions. Subsequently, the tested samples were crushed carefully, to manually recover all roots and to classify the soil. From this study, it was observed that the presence of root fibres within the soil matrix has enhanced the soil strength through a binding action in the fibre-soil composite. The correlation between root content and shear strength is prominent near the surface and becomes less obvious in deeper soil layers when the root concentration becomes more sparsely distributed.

Experimental evaluation of binder infiltration depth and axial overlap to control properties of green parts produced by Binder Jetting

Binder Jetting is a 3D printing process that consists of selectively depositing picoliter-sized droplets of binder on each layer to create a 2D pattern of the part. Controlling the distribution of the binder appears to be critical to improving the bonding of successive layers and limiting binder overflow. In this study, the exact penetration depth of the binder into the powder bed is measured and the amount of vertical overlap between layers is evaluated. The influence of printing parameters such as droplet spacing, layer thickness and drying conditions is investigated. A process mapping is proposed to better select printing parameters and improve green part quality.

Meibography-Guided Electroepilation for Congenital Distichiasis: A Novel Surgical Technique.

Congenital distichiasis is managed either by ablation, using laser, cryotherapy, or electroepilation, or by surgical excision with mucous membrane grafting. Ablative procedures are usually blind as the exact depth of distichiatic eyelashes is unknown. The described surgical technique utilizes meibography for imaging the root and depth of distichiatic eyelashes that aided in performing electroepilation. Six patients (n = 24 eyelids; mean age 15.5 ± 12.2 years) underwent infrared meibography (Oculus Keratograph 5 M) and noninvasive tear breakup time prospectively. Eyelashes were electroepilated using a premarked needle inserted at a depth based on meibography findings in 4 patients. Surgical success was defined as no distichiatic eyelash regrowth and functional success was defined as the resolution of symptoms at a minimum of 3 months of follow-up. All 6 patients had all 4 eyelids involved to varying degrees, with a total of 230 distichiatic eyelashes. The median number of distichiatic eyelashes was 9 in the upper eyelids and 4.5 in the lower eyelids. Meibography revealed visible distichiatic eyelash roots in 70% of eyelashes in the upper eyelid and 87.8% in the lower eyelid, respectively. The median eyelash root depth was 2.7 mm (mean 2.9 mm, range 1.8-5.4 mm). The mean noninvasive tear breakup time was 12.2 seconds despite absent or rudimentary meibomian gland segments seen on meibography. The anatomical success was 75% (12/16 eyelids), and functional success was 87.5% (7/8 eyes) at a median follow-up of 5.5 months. Preoperative infrared meibography in eyelids with congenital distichiasis helps estimate the eyelash depth and can be used to guide eyelash ablation procedures.

Homography-Based Visual Servoing of Eye-in-Hand Robots With Exact Depth Estimation

Visual servoing can effectively control robots using visual feedback to improve their intelligence and reliability. For a feature point detected by a monocular camera, the time-varying depth appearing nonlinearly in the Jacobian matrix is difficult to be measured without the prior geometry knowledge of the observed object. Hence, the depth of the feature point is one of the major uncertain parameters in visual servoing. Considering unknown Cartesian feature positions, this study presents a dynamics-based homography-based visual servoing (HBVS) controller for the three-dimensional (3-D) pose regulation of eye-in-hand robot arms with monocular cameras. The uncertain depth is represented as a linear form of its Cartesian feature position, and a composite learning law is applied to estimate position parameters accurately, resulting in exact depth estimation. Compared to existing adaptive HBVS methods, the distinctive feature of the proposed method is that it is a dynamics-based design and guarantees exact depth estimation under a much weaker condition termed interval excitation than persistent excitation. Simulations and experiments on a collaborative robot with 7 degrees of freedom named Franka Emika Panda have verified the effectiveness of the proposed method.

Multi-scale split matching three-dimensional reconstruction method of surface microcracks on the silicon nitride bearing roller

Aiming at the characteristics of parametric discrete and non-significant depth of silicon nitride bearing roller surface microcracks. A multi-scale split matching method is proposed. To realize the full reconstruction of the characteristics of the three-dimensional morphology of the surface microcracks. Combined with the parametric discretization characteristics of the surface microcracks, a box filter is defined to do second-order Gaussian differentiation on the image. Construct a multiscale Hessian matrix in the scale space of the surface microcrack image. Determine the covariance-discrete feature points, and obtain the global covariance-discrete sparse point cloud of silicon nitride bearing roller surface microcracks by non-maximum value suppression. For the non-significant depth features of silicon nitride bearing roller surface microcracks. Dissect the surface microcrack distortion images. Divide each image into multiple regional pixel blocks and construct an aggregation function to determine the exact depth value of each pixel block at the cost of matching each pixel block with its surrounding pixel blocks. Dense point cloud reconstruction of non-significant depth features of silicon nitride bearing roller surface microcracks is realized. The average distribution of dense clusters of reprojection errors of the dense point cloud features is less than 0.4pix, the median residual of the field of view of the surface microcrack image is 0.57pix, and the total number of effectively extracted feature points is about 92.9 %. The detailed lossless recovery reconstruction of the parametric discrete, non-significant depth features of silicon nitride bearing roller surface microcracks is realized. A new idea is provided for the establishment of molecular dynamics geometric modeling of the surface microcrack extension process on the silicon nitride bearings roller.

Application program interface for automatic segmentation of retinal layers and fluids in Optical Coherence Tomography ‐ Neovascular Age related Macular degeneration retinal images using deep learning models

AbstractOptical coherence tomography is a non‐invasive imaging technique that provides micrometer‐resolution images of retinal structures. These images can assist in identifying changes under the retina's surface, such as edema. This study proposes a novel deep learning model AR U‐Net++ for segmenting retinal layers and fluids. The four retinal layers ILM (Internal Limiting Membrane), IPL (Inner Plexiform Layer), RPE (Retinal Pigment Epithelium), BM (Bruch Membrane), and IRF (Intra Retinal Fluid), SRF (Sub Retinal Fluid), and PED (Pigment Epithelial Detachment) are segmented using AR U‐Net++. The proposed architecture AR U‐Net++ achieves better accuracy (99.67%), mean IoU (0.84), and dice coefficient (0.94) than the existing models of U‐Net, AR U‐Net, and AR W‐Net. The novelty of the suggested model AR U‐Net++ is to identify the exact location and depth of the retinal fluid in between the retinal layers and generating reports that aids the clinicians in the diagnosis of Age related Macular Degeneration.

Experimental Studies of the Seed-Sowing Device for the Grain Seeder SUBM-3.6

Introduction. Laying the groundwork for developing scientific and engineering efforts and for obtaining the results necessary to create technologies, products, goods and services that provide the independence and competitiveness of the domestic agro-industrial complex is one of the main tasks for ensuring the food security of Russia. One of the most important and difficult agricultural operations is sowing carried out by seeders equipped with mechanical, pneumatic or pneumatic-mechanical seed-sowing devices. Aim of the Article. The purpose of the research is to develop an experimental stand and a methodology for conducting experimental studies of the seed-sowing device for a grain seeder to build mathematical models of its performance when sowing various agricultural crops: wheat, rye, barley, oats, millet, vetch. Materials and Methods. The mechanical roller feed unit is used on one of the most popular and applicable seeder, namely the universal block-modular seeder SUBM-3.6. It allows ensuring the uniformity of the seeding rate and the exact depth of seed embedding. These indicators are the main ones in assessing the performance of seeders. Considering the design features of the above-mentioned seeder is an important step in assessing its productivity. Results. One of the main characteristics of the seeders is their productivity. In the article, there are presented the studies aimed at constructing a mathematical model of the dependence of the seeders productivity on the rotational speed of the drive shaft of the working bodies (rollers) pc (min–1) and the operating length of the rollers lc (mm). For this purpose, an experimental stand and methodology for conducting experimental studies of the productivity of the seeders were developed in accordance with modern methods of experiment planning. Discussion and Conclusion. The analytical dependences of the seeding rate on the rotation frequency and the roller operating length obtained as a result of experimental studies will allow the most efficient use of roller feed units that in turn will influence the choice of optimal operating modes of the seeder SUBM-3.6.

High-Fidelity Drone Simulation with Depth Camera Noise and Improved Air Drag Force Models

Drone simulations offer a safe environment for collecting data and testing algorithms. However, the depth camera sensor in the simulation provides exact depth values without error, which can result in variations in algorithm behavior, especially in the case of SLAM, when transitioning to real-world environments. The aerodynamic model in the simulation also differs from reality, leading to larger errors in drag force calculations at high speeds. This disparity between simulation and real-world conditions poses challenges when attempting to transfer high-speed drone algorithms developed in the simulated environment to actual operational settings. In this paper, we propose a more realistic simulation by implementing a novel depth camera noise model and an improved aerodynamic drag force model. Through experimental validation, we demonstrate the suitability of our models for simulating real-depth cameras and air drag forces. Our depth camera noise model can replicate the values of a real depth camera sensor with a coefficient of determination (R2) value of 0.62, and our air drag force model improves accuracy by 51% compared to the Airsim simulation air drag force model in outdoor flying experiments at 10 m/s.

Planar Slope Failure in Heavily Jointed Rock: Tension Cracks and Nonlinear Strength

This work proposes the calculation of the factor of safety for a strongly jointed rock mass in the case of plane failure with a tensile crack whose exact position or depth is not known but is expected to exist. This calculation is performed by applying the non-linear failure criteria of the Focus Procedure of Úcar and Hoek–Brown’s and implementing the necessary formulae in a spreadsheet. The aim is to provide a simple, cost-effective, and easy-to-use procedure that is useful in the early stages of a project or as a starting point for more detailed investigations. Besides slope geometry and strength parameters, the required parameters are the RMR of the rock mass or its mi, depending on the criterion used. The proposed procedure allows for the estimation of the factor of safety, the position and depth of the tensile crack, and the inclination of the failure plane in the most unfavorable case, with reasonable accuracy, using an iterative process with the conventional tools available in common spreadsheet programs. An example is provided in which an accuracy of 86–96% for the factor of safety is obtained.

Quantifying Shallow-Depth Concrete Delamination using Impact-Echo

Corrosion-induced concrete deck delamination is quite common in bridges. Locating these embedded delaminations is important to assess the extent of the damage, the remaining member capacity and any necessary rehabilitation. The impact-echo (IE) is a simple and straightforward non-destructive testing (NDT) technique by which the depth and extent of concrete delamination may be estimated. It is effective in detecting the location and determining the depth of relatively deep delaminations in concrete. Delaminations that occur near the concrete surface can also be detected by the IE method. However, the exact depth cannot be quantified due to difficulties in analysing the flexural mode that dominates the vibration response over the corresponding delaminated region. This study developed an IE-based procedure to quantitatively estimate the depth of shallow depth delaminations in concrete slab members. Four slab specimens were prepared, each with three artificial delaminations with varying shapes and sizes at shallow depths. The frequency contour maps showed good agreement with the actual location of the delaminations. The perimeter-to-depth ratio of the delaminated region can be used to analyze the flexural mode vibration frequency. Two equations are proposed that relate the depth of arbitrarily shaped delaminations to the flexural mode vibration frequency measured over the shallow-depth delaminations. Keywords: impact echo, concrete delamination, concrete slabs, flexural mode vibration, non-destructive evaluation (NDE)

What did COVID-19 really teach us about science, evidence and society?

What did COVID-19 really teach us about science, evidence and society?

Thoughts and Concepts in Ultrasonography-guided Hyaluronidase Injection Technique.

INTRODUCTION The number of people receiving facial filler injections for aesthetic purpose has been increasing in recent years. Simultaneously, the number of patients dissolving fillers due to unsatisfactory outcomes or adverse effects, such as granuloma and allergy, is also increasing. Hyaluronidase has various uses, including dissolving hyaluronic acid fillers and treating granulomatous foreign body reactions and necrosis associated with filler injections.1 Here, I will discuss why ultrasonography should be performed before a filler dissolving injection and why the filler should be dissolved while viewing ultrasonographic images.2 Hyaluronidase is an endoglycosidase that breaks down hyaluronic acid into monosaccharides by cleaving its glycosidic bonds.3,4 Safe performance of this method requires sufficient understanding of the anatomy of the face, because of the heavy distribution of vital blood vessels, nerves, retaining ligaments, and muscles.5 The author performed filler removal using ultrasonography on more than 500 patients. First, palpation was performed, and after confirming the exact location and depth with ultrasound, it was marked with a pen. The filler was removed by injection of hyaluronidase. Some people had swelling and heat due to allergy to hyaluronidase, but they improved within 2–3 days and did not experience any other side effects (Fig. 1). This ultrasonography-guided hyaluronidase injection technique offers several advantages, as follows:Fig 1.: Pre- and post-procedure ultrasonic images. A, Filler in the anterior cheek shown before hyaluronidase injection. B, Anterior cheek after the filler has been completely dissolved. Ultrasonography is rapid and simple, with no risk of radiation exposure. This technique involves no additional discomfort for patients and can be more comfortable. This method does not require injection into a wide area around the injected filler, indicating that a smaller amount of hyaluronidase can be used. Vital blood vessels and nerves can be avoided using ultrasonographic images. When catastrophic adverse effects (such as blindness or necrosis) occur, exacerbation of such adverse effects can be quickly and accurately prevented. This method can effectively dissolve the filler, as the target is accurately set beforehand. In cases wherein undissolved fillers are still present despite several dissolution procedures, ultrasonography-guided hyaluronidase injection before removing the filler by incision is a feasible approach for both the patient and the physician. A limitation is that it is very difficult to completely remove granuloma or filler if it remains in a very small size, or if the filler is broken into very small sizes by melting it. In addition, there are cases in which the filler cannot be confirmed by ultrasound. The use of more precise ultrasound is necessary. This study is a conceptual thought and represents the author’s opinion based on experience, and a more scientific study with 500 patients will be conducted in the future. DISCLOSURE The author has no financial interest to declare in relation to the content of this article.

Design and analysis of a super compact UWB antenna for accurate detection of breast tumors using monostatic radar‐based microwave imaging technique

AbstractThis article proposes a low‐profile ultra‐wideband (UWB) antenna for breast tumor detection using the monostatic radar‐based microwave imaging (RBMI) technique. The proposed UWB antenna consists of a circular patch and ground plane along with a modified tapered feed line having a total size of 13 × 9 × 1.6 mm3. The designed antenna operates from 4 to 11 GHz based on a −10 dB reflection coefficient with a peak gain of 9.5 dBi at 4.8 GHz. Experimental validation is carried out after fabricating the prototype of the UWB antenna and the breast mimic. The measured backscattered signals are captured using the vector network analyzer (E‐5063A) by keeping the antenna at 10 mm from the breast phantom. After that, post‐processing of the measured data is done to detect the exact depth and location of the malignant tissue. The proposed antenna uses UWB band frequency of operation because it has some unique features, that is, it provides immunity to multipath fading, has a simple design, has a low cost of fabrication, and has biological friendliness. Moreover, due to the proposed antenna's resonance at a lower resonant frequency better depth of penetration is achieved in human body phantoms and the proposed antenna provides specific absorption rates (SAR) of 0.877 W/kg over 1 g of tissue at 4.8 GHz, which is an acceptable limit for SAR as per FCC guidelines. Therefore, the proposed antenna and monostatic RBMI technique are good candidates for breast tumor detection.

Geophysical research of underground hydraulic structures, old Glubochinsky water tunnel case study

Research objective is to study the features of geophysical fields and parameters in the area of the artificial underground water tunnel and estimate the capabilities of geophysical methods of identifying hidden underground industrial facilities. Methods of research. Measurements of self-potential signals (SP) were carried out using nonpolarizing electrodes and an electrical exploration receiver. The magnetic exploration was carried out by a proton magnetometer. Electrotomography was carried out using multielectrode electrical survey equipment with a Schlumberger symmetrical scheme of surveys. The microseismic background was recorded using an autonomous seismic station. The georadar survey was carried out using the SIR-3000 ground penetrating radar and antennas with the frequencies of 100 MHz and 270 MHz. Results. Based on the survey results, graphs of magnetic and self-potential fields, electrotomographic and microseismic sections, and radarogram were built on the research profile. The research has shown different levels of the magnetic field and the SP in the area of volcanic rocks and dikes of gabbro-dolerites occurrence. A significant increase in microseismic noise was observed with an increase in the weathering crust thickness. A local decrease in the SP potential, abnormally high values of specific electrical resistivity and intensive reflections of radio waves from the tunnel top were recorded above the underground water tunnel. Conclusions. Qualitative and quantitative geophysical characteristics were obtained in the area of the old underground water tunnel. The research showed different levels of the magnetic field and spontaneous polarization potentials in the occurrence area of rocks of different composition. A significant increase in microseismic noise was recorded with an increase in the weathering crust thickness. Geophysical signs of the boundaries between geological structures and artificial underground objects are revealed. The exact position and depth of the old underground tunnel of Glubochinsky hydraulic structures was determined.

Knowledge of scope of oral and maxillofacial surgery amongst medical students at a tertiary hospital in Kathmandu, Nepal

Background: Diagnosis and surgical treatment of varieties of traumatic, pathologic, functional, and aesthetic disorders of stomatognathic system are included in the scope of oral and maxillofacial surgery (OMFS). Although this speciality plays a significant part in dentistry and medicine; dental and medical professionals still do not fully comprehend the exact depth. Objectives: To understand the level of knowledge amongst medical students of different levels, to promote the scope of OMFS among health care communities, and establish a fair understanding of the speciality’s contribution. Methods: This questionnaire based descriptive, cross-sectional survey was done on purposive sampling technique. Data were collected from 2022 October to 2022 December among medical students and interns of Nepal Medical College via questionnaire after receiving institutional ethical clearance. Data were entered, coded, and edited using Microsoft Excel 2010 and analysed using SPSS v.20. Descriptive statistics are presented in frequency, percentage, and mean. Results: A total of 254 study participants were included of which 149 (58.66%) were male and 105 (41.34%) were female. Of all, 99 (38.98%) were first year medical students, 80 (31.50%) were second year students, and 75 (29.53%) were interns. Mean knowledge score in preclinical students was 6.27 ± 1.73 and 7.12 ± 1.85 in interns. The result shows adequate knowledge for both groups. Conclusion: Findings of this study assesses the level of knowledge of medical students at a tertiary hospital which will help to highlight the need for awareness and education regarding OMFS, promoting its development, contribution, and impact among the health care professionals.

Imaging the magmatic plumbing of the Clear Lake Volcanic Field using 3-D gravity inversions

The Quaternary Clear Lake Volcanic Field (CLVF) in the Northern California Coast Range is the youngest of a string of northward-younging volcanic centers in the state. The CLVF is located within the broad San Andreas Transform Fault System and has been active intermittently for ∼2 million years. Heat beneath the CLVF supports The Geysers, one of the largest producing geothermal fields in the world.Previous geophysical studies proposed the existence of a magma reservoir beneath Mount Hannah, which is northeast of The Geysers, near the geographic center of the CLVF. The lateral extent, depth, and presence of melt within this reservoir are poorly constrained, as is the relationship between this body and the broader magmatic plumbing of the CLVF. To gain a clearer and more comprehensive picture of the CLVF magma source region, a gravity dataset was compiled and the first 3-D gravity inversions of the CLVF were completed.Field and synthetic model inversions from the current study both indicate that the gravity low roughly centered on Mount Hannah is not accurately explained by a 5–7 km thick lens of Mesozoic Great Valley Sequence (ρ=2.58g/cm3) as proposed by Stanley et al. (1998). The observed gravity low is more accurately described by one or more silicic, partial melt bodies between The Geysers and Mount Hannah. Although our inversions cannot constrain the exact depth and geometry of these bodies, the recovered models indicate the existence of a partial melt zone between 6 and 13 km depth.The prolonged eruption history of the CLVF, coupled with the compositional variation of erupted rocks over time and space, is consistent with the existence of several, potentially ephemeral, melt-bearing bodies as opposed to one large melt body. Given the density and location of the recovered anomaly, rhyolite-MELTS thermodynamic modeling suggests the existence of 10–30% rhyodacitic melt within the proposed silicic magma reservoir at about 700 °C and 8 km depth (210 MPa). Independent petrologic, geochemical, and seismic evidence indicates that this silicic partial melt zone is underlain by basaltic melt in the lower to middle crust (13 to 21 km depth), which is fed by a mantle source.Eruptions in the past ∼8.5–13.5 thousand years; high regional heat flow; 3He enrichment of hydrothermal fluids; and our modeling, which suggests the presence of a mid-crustal, silicic partial melt zone, point to a still-active CLVF. The relatively low estimates of partial melt (10–30%) predicted by thermodynamic modeling indicates that an injection of new magma into the imaged partial melt zone is needed to generate sufficient melt to incite future eruptions. Despite the low percent melt estimates within the proposed silicic partial melt zone the potential for future volcanic eruption remains. Due to the proximity of the CLVF to cities surrounding Clear Lake and the densely populated San Francisco Bay Area, continued research and monitoring of the volcanic field are warranted. The geophysical and petrologic modeling presented here improves our understanding of the CLVF magma plumbing system and allows us to better characterize its associated volcanic hazards.