Local Reference Research Articles

Estimation of radiation dose associated with bone SPECT/CT and establishing local diagnostic reference levels using size-specific dose estimate

Single-photon emission computed tomography (SPECT) and X-ray computed tomography (CT) is used to diagnose and monitor the skeletal system. However, due to the combination of injected activity and CT radiation dose, its usage is linked to an increase in patient radiation exposure. This study aims to estimate the radiation dose received by patients while undergoing bone SPECT/CT and to establish its local diagnostic reference level (LDRL). In this retrospective study, data from 30 patients who had undergone bone scans were obtained from two hospital imaging devices. The effective doses (E) of the radiopharmaceutical agent and CT components were calculated. Furthermore, the patients' anteroposterior thickness at the midline and lateral widths were measured from their CT images to determine the size-specific dose estimate (SSDE). The mean age of the patients was 53.53 ± 16 years. They were administered an injection activity of 740 MBq of 99mTc-Methyl diphosphonate for SPECT, yielding an E of 2.78 mSv. The mean CTDIvol, DLP, SSDE, and E values for the CT component were 8.76 ± 3.25 mGy, 350 ± 138 mGy cm, 13 ± 4 mGy, and 4.90 ± 1.94 mSv, respectively. Patients received a combined dose of 7.68 mSv from the radiopharmaceuticals and CT. The proposed LDRL for SPECT was comparable to international DRLs, but the CT LDRL was slightly higher. An SSDE-based LDRL is proposed. Moreover, the overall patient dose can be reduced even further by optimizing the injected activity and CT imaging factors.

NUCLEAR MEDICINE PROCEDURE VOLUME AND ESTIMATION OF COLLECTIVE EFFECTIVE DOSE IN TAMIL NADU TOWARDS THE ESTABLISHMENT OF DIAGNOSTIC REFERENCE LEVEL.

With an objective to establish adult diagnostic reference levels in the practice of nuclear medicine (NM) in the state of Tamil Nadu (TN), data on the predominant NM procedures carried out in the state are analyzed. In this study, data on total NM diagnostic procedures during the years 2015-19 along with patient-specific diagnostic NM procedure data for the period April-June 2021 from all centers in Tamil Nadu are collected and analyzed using SPSS statistical software. Nine predominant types of NM scans are analyzed. Collective effective dose from NM scans and per capita dose for the TN population are estimated. The 75th percentile of the distribution and average administered activity (AAA) has been derived and local reference levels are reported. Based on the statistical analysis, it is observed that the whole-body positron emission tomography (PET), renal diethylenetriamine pentaacetate (DTPA) scan, bone methylene diphosphonate (MDP) scan, iodine-131 whole body scan, thyroid studies using Technetium per technetate, renal dimercaptosuccinic acid (DMSA), myocardial perfusion methoxyisobutyl isonitrile sestamibi (MIBI), mebrofenin, Galium-68 prostate-specific membrane antigen (PSMA) are the most common procedure covering >90% of the practices carried out. The collective effective dose is 410 man-Sv in the year 2019, leading to a mean effective dose of 0.006mSv per capita of the TN state population. The 75th percentile of the distribution of AA is slightly higher than diagnostic reference level (DRL) as compared with Australian DRL (310MBq). It is also observed that F-18 PET procedures are primarily responsible for most of the collective effective dose, local DRL is 316MBq and it is important to establish national DRLs for NM diagnostic scans to optimize the NM examinations.

Establishment of local diagnostic reference levels for common adult CT examinations: a multicenter survey in Addis Ababa

BackgroundIn medical imaging, a computed tomography (CT) scanner is a major source of ionizing radiation. All medical radiation exposures should be justified and optimized to meet the clinical diagnosis. Thus, to avoid unnecessary radiation doses for patients, diagnostic reference levels (DRLs) have been used. The DRLs are used to identify unusually high radiation doses during CT procedures, which are not appropriate for the clinical diagnosis. It has been successfully implemented in Europe, Canada, Australia, the United States, several industrialized countries, and a few underdeveloped countries. The present study aimed to establish DRLs for the head, chest, and abdominopelvic (AP) CT procedures in Addis Ababa, Ethiopia.MethodsA pilot study identified the most frequent CT examinations in the city. At the time of the pilot, eighteen CT scan facilities were identified as having functioning CT scanners. Then, on nine CT facilities (50% of functional CT scanners), a prospective analysis of volume CT dose index (CTDIvol) and dose length product (DLP) was performed. We collected data for 838 adult patients’ head, chest, and AP CT examinations. SPSS version 25 was used to compute the median values of the DLP and CTDIvol dose indicators. The rounded 75th percentile of CTDIvol and DLP median values were used to define the DRLs. The results are compared to DRL data from the local, regional, and international levels.ResultThe proposed DRLs using CTDIvol (mGy) are 53, 13, and 16 for the head, chest, and AP examinations respectively, while the DLP (mGy.cm) for the respective examinations were 1210, 635, and 822 mGy.cm.ConclusionBaseline CT DRLs figures for the most frequently performed in Addis Ababa were provided. The discrepancies in dose between CT facilities and as well as between identical scanners suggests a large potential for dose optimization of examinations. This can be actually achieved through appropriate training of CT technologists and continuous dose audits.

Site-based description of R1ρ relaxation in local reference frames

Nuclear magnetic spin relaxation in the presence of an applied radiofrequency field depends critically on chemical exchange processes that transfer nuclear spins between chemical or conformational environments with distinct resonance frequencies. Characterization of chemical exchange processes in R1ρ relaxation dispersion, CEST, and DEST experiments provides powerful insights into chemical and conformational kinetics of biological macromolecules. The present work reformulates expressions for magnetization evolution and the R1ρ relaxation rate constant by focussing on the orientations of the tilted rotating frames of reference for magnetization components in different sites, by treating the spin-locking field strength as a perturbation to free-precession evolution, and by applying the Homotopy Analysis and Laplace transform methods to approximate solutions to the Bloch-McConnell equations. The results provide an expression for R1ρ that is invariant to the topology of the kinetic scheme, an approximate equation for evolution of spin-locked z-magnetization, and an approach for effective simplification of chemical exchange topologies for 2- and N-site chemical exchange processes. The theoretical approach also provides an accurate approximation for relaxation during a constant-amplitude radiofrequency field in the absence of exchange.

Parathyroid hormone reference intervals in adults using second- and third-generation assays

Parathyroid hormone (PTH) is a routine biochemical analysis, and it varies whether a second- or third-generation assay is used. Information on the levels obtained with different assays and evidence to substantiate local assay-specific reference ranges are important to inform clinical practice. Prior to a shift from the second- to the third-generation PTH assay (Cobas 8000, Roche Diagnostics) in the Department of Clinical Biochemistry, Aalborg University Hospital, Aalborg, Denmark, a total of 59 EDTA-plasma samples were collected for method comparison (Passing–Bablok). Furthermore, 120 EDTA-plasma samples were randomly obtained from adult blood donors and used for the establishment of reference intervals using the third-generation PTH assay (Cobas 8000, Roche Diagnostics) and two second-generation assays (Atellica, Siemens Healthineers; Alinity, Abbott Laboratories). Method comparison (Cobas 8000, Roche Diagnostics) showed lower levels with the third-generation (y) as compared to the second-generation assay (x) depending on the measurement range (PTH < 10 pmol/L: y = 0.8 (95% CI: 0.7; 0.9) x + 0.3 (95% CI: 0.2; 0.5), PTH ≥ 10 pmol/L: y = 0.6 (95% CI: 0.5; 0.6) x + 3.2 (95% CI: 1.1; 5.2)). Method-specific reference intervals (2.5 and 97.5 percentiles) after the exclusion of samples (n = 31) with 25-hydroxy-vitamin D below 50 nmol/L were: 1.8–8.5 pmol/L (second-generation, Atellica, Siemens Healthineers); 2.4–10.9 pmol/L (second-generation, Alinity, Abbott Laboratories), and 1.8–7.0 pmol/L (third-generation, Cobas 8000, Roche Diagnostics). PTH levels with second- and third-generation assays are not interchangeable. Clinicians should be informed when a laboratory assay is changed, and method-specific reference ranges are needed.

Lexical Portrait of an Oral Story: a Corpus Study of Speech of Two Generations of Native Speakers of Russian

The article is devoted to the quantitative and statistical analysis of the vocabulary of the oral stories corpus based on pictures. The subjects were 42 people, monolingual native speakers of the Russian (representatives of 15 families). The purpose of the study is to identify and describe the lexical parameters that distinguish the oral stories of representatives of different generations. An attempt is made to consider the connection of these parameters with the formation of native speakers’ ideas about the lexical structure of the narrative. The following results are obtained. The nature of the stimulus material ensured an approximately equal degree of complexity in the texts of both groups, although the volume of the parents’ active vocabulary significantly exceeded the volume of the children’s vocabulary. At the level of individual texts, both groups use equally diverse vocabulary per unit of text volume. In the children’s stories, the main “plot” vocabulary is quite heterogeneous, while the parents tend to lexical unification of the narrative. In the texts of both groups, local reference and direction of movement are expressed in the same way, which indicates their “basic” narrative function, which does not depend on the age of the subjects. The stories of the parents are also unified in terms of vocabulary, showing the logical structure of the narrative and different types of semantic relations in the text.

Local reference and achievable dose levels for vascular and enterostomy access procedures in pediatric interventional radiology.

Knowledge of radiation quantities delivered in routine practice is an essential responsibility of a pediatric interventional radiology department. To review radiation indices in frequently performed vascular and enterostomy access procedures at a quaternary pediatric hospital to formulate dosimetric reference levels and achievable levels. A retrospective review of patient demographics, procedure information and quantitative dose metrics over a 2-year period was performed. Dosimetric details forcommon procedures (central line insertions, gastrostomy/gastrojejunostomy insertions and maintenance) were evaluated, correlated with demographic data and stratified acrossfive weight groups (0-5kg, 5-15kg, 15-30kg, 30-50kg, 50-80kg).Achievable (50th percentile) and reference (75thpercentile)levels with confidence intervals were established for each procedure. Within the evaluation period, 3,165 studies satisfied the inclusion criteria. Five were classified as device insertions (peripherally inserted central catheter, n=1,145; port-a-catheter, n=321; central venous line, n=285; gastrostomy-tube [G-tube], n=262, and gastrojejunostomy-tube [GJ-tube], n=66),and two were classified as maintenance procedures (G-tube, n=358, and GJ-tube, n=728, checks, exchanges and reinsertions). Representative reference and achievable levels were calculated for each procedure category and weight group. This work highlights the creation of local reference and achievable levels for common pediatric interventional procedures. These data establish a dosimetric reference to understand the quantity of radiation routinely applied, allowing for improved relative radiation risk assessment and enriched communication to interventionalists, health care providers, parents and patients.

Analysis of Local Diagnostic Reference Levels for Pediatric Patients Undergoing 18F-FDG PET/CT Imaging for Oncology

Analysis of Local Diagnostic Reference Levels for Pediatric Patients Undergoing 18F-FDG PET/CT Imaging for Oncology

A Comparison of the Mean CTDIvol and DLP Values for Adult Abdominal CT Examination for MTRH, Eldoret Hospital, St. Luke’s Hospital and Mediheal Hospital: A Retrospective Study

Background: Advances in Computed Tomography (CT) have facilitated widespread use of medical imaging while increasing patient lifetime exposure to ionizing radiation. In Kenya we use the international DRLs as our point of reference and so far, no regional protocols for abdominal CT scan have been adopted. This study endeavors to form a basis for dose reference levels protocols for abdominal CT scan in Uasin Gishu County. Objective: To compare the mean CTDIvol and DLP values for adult abdominal CT examination for MTRH, Eldoret Hospital, St. Luke’s Hospital and Mediheal Hospital. Methods: This was a retrospective review of CT scans of 700 adult patients conducted in Uasin Gishu healthcare system at MTRH, Eldoret Hospital, Mediheal Hospital and St. Luke’s Hospital in a period of 1 year in the year 2021 using systematic and consecutive sampling. The Volumetric CT-dose index (CTDIvol) and dose length product (DLP) length from CT abdominal scans for the adults were collected from the various CT scans dose tracking software’s. Results: The mean age of patients who underwent CT abdominal scans was 52 years with majority being females at 53 %. The mean CTDIvol was 81. (SD=22.2) and the mean DLP values was 1699.1 (SD=1053.1). Comparison by scan model demonstrated the median for the Total DLP and for the CTDIvol significantly differed by the model with the median for the Neusoft model being highest at 2538 mGy.cm and 10.3mGy respectively while those for the Siemens were the lowest for the two markers at 1318.5 mGy.cm for the DLP and 5.39mGy respectively. These findings were statistically significant with a p value of &lt; 0.001. Comparison by the type of facility showed that the median DLP and CTDIvol values were significantly higher in the public facilities at 1668.8mGy.cm and 6.3mGy respectively when compared to private facilities at 1282.4mGy.cm and 5.9mGy with a p value of &lt;0.001. The Local Dose reference level (LDRL) was set as the median value for CTDIVOL and DLP at 6.1mGy and 1465 mGy.cm respectively. Conclusions: The LDRLs for the patients undergoing abdominal CT examination in Uasin Gishu healthcare system were markedly lower than the regional and the international values for the same abdominal CT examination.

Statistical study for Radiation Dose Reference levels of Adult Computer Tomography Abdominal studies in Eldoret Kenya

Objective: To establish dose reference levels for the adult abdominal CT scan modality at MTRH, Eldoret Hospital, St. Luke’s Hospital and Medi heal Hospital in reference to the international DRLs. Methods: A retrospective study, reviewed CT scans of 700 adult patients conducted in the 4 health institutions from Uasin Gishu healthcare system in a period of 1 year in the year 2021 using systematic and consecutive sampling. The Volumetric CT-dose index (CTDIvol) and dose length product (DLP) length from the various adult CT abdominal scans were obtained. Results: The mean CTDIvol was 8.1 (22.2) and the mean DLP values was 1699.1 (1053.1). Comparison by scan model it was observed that the median for the Total DLP and for the CTDIvol significantly differed by the model with the median for the Neusoft model being highest at 2538 mGy.cm and 10.3mGy respectively while those for the Siemens were the lowest for the two markers at 1318.5 mGy.cm for the DLP and 5.39mGy respectively. These findings were statistically significant with a p value of &lt; 0.001. Comparison by the type of facility it was observed that the median DLP and CTDIvol values were significantly higher in the public facilities at 1668.8mGy.cm and 6.3mGy respectively when compared to private facilities at 1282.4mGy.cm and 5.9mGy with a p value of &lt;0.001.The Local Dose reference level (LDRL) was set as the median value for CTDIVOL and DLP at 6.1mGy respectively. Conclusions: The LDRLs for the adult patients undergoing abdominal CT examination in Uasin Gishu healthcare system were markedly lower than the regional and the international values for the same abdominal CT examination.

Radiation Dose Survey of Pediatric Chest Computed Tomography Examinations: A Local Diagnostic Reference Levels Approach to Patient Safety

Radiation Dose Survey of Pediatric Chest Computed Tomography Examinations: A Local Diagnostic Reference Levels Approach to Patient Safety

Haematology Parameters of Apparently Healthy Prospective Whole Blood Donors in a Nigerian Hospital Setting

Background: Adequate selection of a prospective whole blood donor protects his health and safety of the recipient. Objectives: The main objective of this study was to determine the haematology parameters of apparently healthy prospective whole blood donors. Participants and Methods: This was a hospital based prospective study carried out from August to October 2020 at the blood transfusion unit of the Lagos State University Teaching Hospital (LASUTH), Ikeja, Nigeria. A structured pretested questionnaire was used for data collection. The socio demographic status and the haematology parameters of apparently healthy prospective whole blood donors who tested negative for HIV, hepatitis B and C markers were captured. Obtained data were analysed with the statistical package for the social scientist software version 20. Results: One hundred male (97.1%) and three female (2.9%) apparently healthy prospective whole blood donors were studied. The median age of study subjects was 30 years. Obtained median haematology parameter values were 13 g/dl, 40%, 4.9/nl and 203.9/nl for haemoglobin concentration, haematocrit, total white cell and platelet counts respectively. The median values for the mean corpuscular haemoglobin concentration (MCHC), mean corpuscular haemoglobin (MCH) and mean corpuscular volume (MCV) of participants were 32.6 g/dl, 27.7 pg and 85.7 fl respectively. Observed prevalence of subnormal haematology parameters for haemoglobin concentration, total white cells, platelets were 12.6%, 25.2%, and 13.6% respectively. Also subnormal values for MCHC, MCH, MCV were 11.7%, 26.2%, and 16.5% respectively among prospective whole blood donors in this study. No higher than normal haematology parameter values were observed. Median values for erythrocyte sedimentation rate was 8.4 mm/hr. Conclusion: A significant percentage of apparently healthy prospective whole blood donors had subnormal haematology parameters values. Obtained normal values in our study are comparable with local reference range reports from previous studies in Nigeria and other parts of Africa. 124947

Establishment of Complete Capillary Blood Counts Reference Intervals for Young Children in Local Area, China.

Blood count reference intervals are important to diagnose diseases and assess overall health, especially for young children. Although, in 2021, the National Health Commission of the People's Republic of China issued "Reference intervals of blood cell analysis for children (WS/T 779-2021)", these RIs may not suitable for small children all over the country due to racial, lifestyle, and geographical differences. The aim of this study was to establish and validate locally determined hematological reference intervals among young children in Nantong district and compare them with WS/T 779-2021 and American data. The reference sample consisted of 4,758 apparently healthy small children aged from age 28 days to 3 years according to the EP28-A3c guideline issued by the Clinical and Laboratory Standards Institute (CLSI). Capillary blood samples collected in K2-EDTA anticoagulant tubes analyzed by standard procedures. Statistical analysis was based on the guidelines of the CLSI. Pediatric reference intervals for 18 capillary complete blood count (CCBC) parameters were established for young children. WBC and differentials did not differ by gender in the combined analysis of all data, but showed some variations among different age groups, especially for NE and LYM. RIs of RBC value, MCV, and MCH were established, especially with regard to the difference among different age and gender groups. An overall increasing trend of PLT value was observed in children with no obvious difference between boys and girls. Further validation with 1,136 healthy subjects demonstrated that the verified proportions of our study were within 90.11% - 100%. RIs determined in the present study were more concentrated than WS/T 779-2021, with slight differences in the upper and bottom boundaries. Establishing appropriate region-specific reference intervals for pediatrics is essential. This study offers local reference intervals of CCBC values for young children and could be used as a benchmark for similar populations in the Yangtze River Delta economic region.

Autonomous coordinate establishment of local reference frames for ground-based positioning systems without known points

Autonomous coordinate establishment of local reference frames for ground-based positioning systems without known points

Serum Free Light Chain Reference Intervals in a Local Population in Spain using the Optilite Analyser

Our aim was to establish local reference intervals for k and λ free light chains. Fresh sera from 246 healthy blood donors were analyzed to evaluate reference intervals for FLC. CLSI EP28-A3C protocol was applied to establish new RIs. The 95% reference interval for FLCk was 7.20 - 20.0 mg/L, and that for FLCλ was 6.72 - 20.23 mg/L. The diagnostic interval for the k/λ ratio was 0.5 - 2.11 mg/L. When we analyze the distribution of the k/λ ratio results for the 1,025 pieces of data collected using the diagnostic intervals reported by the manufacturer and those established in this study, we observed that discordant results were reported in 14.5% of patients with MGUS and 16.3% of patients with multiple myeloma. Our findings underline the importance of establishing the reference intervals for serum FLCs and the proper diagnostic interval by instrument platform and appropriate to the target study patient population.

Mapping 3D grain and precipitate structure during in situ mechanical testing of open-cell metal foam using micro-computed tomography and high-energy X-ray diffraction microscopy

• 3D grain structure is mapped and tracked during loading of open-cell metal foam. • Challenges included sample size relative to beam size and large ligament motions. • X-ray CT and far-field HEDM measurements collected at incremental displacements. • New scanning and stitching methodology established for far-field HEDM measurements. • Ligament-tracking code used to express crystal orientation in local reference frame. Open-cell metal foams are ultra-low-density cellular metals with complex hierarchical structures that span bulk, cell, ligament, and sub-ligament scales and give rise to desirable properties such as high strength-to-weight ratio and excellent energy absorption. Although literature suggests that intrinsic material structures at sub-ligament length scales (e.g., grains and precipitates) play an important role in mechanical behavior of open-cell metal foams, there are very few experimental measurements of such structures in three dimensions and for meaningful volumes of foam. This study seeks to map and track the three-dimensional (3D) grain and precipitate structures of an intact volume of open-cell aluminum foam by advancing microstructural characterization techniques that leverage X-ray micro-computed tomography ( μ CT ) and far-field high-energy X-ray diffraction microscopy (FF-HEDM). A 6%-relative-density aluminum foam sample was mechanically tested in compression while μ CT and FF-HEDM measurements were collected at interrupted loading states at beamline 1-ID of the Advanced Photon Source. A new scanning strategy and reconstruction algorithm were established to enable characterization of a foam volume with diameter approximately four times wider than the nominal width of the X-ray beam. The result is a set of maps that detail both the 3D grain and precipitate structures throughout the foam volume at successive strain steps. A novel grain tracking procedure was developed to track individual grains within the foam volume by accounting for the large rigid-body motions that individual ligaments can undergo during mechanical loading. The ability to track grains and precipitate structures in three dimensions throughout large bulk deformation of ultra-low-density polycrystalline materials enables new possibilities for validating numerical models and investigating local failure mechanisms. Furthermore, the methods and procedures developed in this study could be applied to other ultra-low-density structures, such as additively manufactured lattices.

Vortex Lens: Interactive Vortex Core Line Extraction using Observed Line Integral Convolution.

This paper describes a novel method for detecting and visualizing vortex structures in unsteady 2D fluid flows. The method is based on an interactive local reference frame estimation that minimizes the observed time derivative of the input flow field v(x, t). A locally optimal reference frame w(x, t) assists the user in the identification of physically observable vortex structures in Observed Line Integral Convolution (LIC) visualizations. The observed LIC visualizations are interactively computed and displayed in a user-steered vortex lens region, embedded in the context of a conventional LIC visualization outside the lens. The locally optimal reference frame is then used to detect observed critical points, where v=w, which are used to seed vortex core lines. Each vortex core line is computed as a solution of the ordinary differential equation (ODE) · w(t)=w(w(t), t), with an observed critical point as initial condition (w(t0), t0). During integration, we enforce a strict error bound on the difference between the extracted core line and the integration of a path line of the input vector field, i.e., a solution to the ODE · v(t)=v(v(t), t). We experimentally verify that this error depends on the step size of the core line integration. This ensures that our method extracts Lagrangian vortex core lines that are the simultaneous solution of both ODEs with a numerical error that is controllable by the integration step size. We show the usability of our method in the context of an interactive system using a lens metaphor, and evaluate the results in comparison to state-of-the-art vortex core line extraction methods.

A Robust LiDAR SLAM Method for Underground Coal Mine Robot with Degenerated Scene Compensation

Simultaneous localization and mapping (SLAM) is the key technology for the automation of intelligent mining equipment and the digitization of the mining environment. However, the shotcrete surface and symmetrical roadway in underground coal mines make light detection and ranging (LiDAR) SLAM prone to degeneration, which leads to the failure of mobile robot localization and mapping. To address these issues, this paper proposes a robust LiDAR SLAM method which detects and compensates for the degenerated scenes by integrating LiDAR and inertial measurement unit (IMU) data. First, the disturbance model is used to detect the direction and degree of degeneration caused by insufficient line and plane feature constraints for obtaining the factor and vector of degeneration. Second, the degenerated state is divided into rotation and translation. The pose obtained by IMU pre-integration is projected to plane features and then used for local map matching to achieve two-step degenerated compensation. Finally, a globally consistent LiDAR SLAM is implemented based on sliding window factor graph optimization. The extensive experimental results show that the proposed method achieves better robustness than LeGO-LOAM and LIO-SAM. The absolute position root mean square error (RMSE) is only 0.161 m, which provides an important reference for underground autonomous localization and navigation in intelligent mining and safety inspection.

Analisis Koleksi Perpustakaan Berdasarkan Standar Perpustakaan Perguruan Tinggi (Studi kasus di Perpustakaan UIN Sunan Gunung Djati Bandung)

This study aims to analyze the library collections of UIN Sunan Gunung Djati Bandung according to the National Library-University Standard (SNP-PT) and the Standard for Libraries in Higher Education. The research method uses descriptive qualitative. Data were collected by observing, in-depth interviews, analysis of various related documents, field notes, and triangulation. The results of the analysis show that based on the SNP-PT standard, the collection indicators that have met the standards include type and number, development, collection of local content, reference collection, and processing. The indicators for re-counting, weeding, preserving, and converting book collections to digital format have not been carried out as stipulated by the standard. Based on the Standard for Libraries in Higher Education, the collection indicators that have been met include the type and format of the collection, access to the collection, and the uniqueness of the collection. Meanwhile, the indicators for the availability of collections, processing infrastructure, information literacy, and the availability of long-term access have not met the standards due to the limited budget and number of human resources with special competencies in the field of information literacy and media transfer.

A geometrically intrinsic lagrangian-Eulerian scheme for 2D shallow water equations with variable topography and discontinuous data

We present a Lagrangian-Eulerian scheme to solve the shallow water equations in the case of spatially variable bottom geometry. This work was dictated by the fact that geometrically Intrinsic Shallow Water Equations (ISWE) are characterized by non-autonomous fluxes. Handling of non-autonomous fluxes is an open question for schemes based on Riemann solvers (exact or approximate). Using a local curvilinear reference system anchored on the bottom surface, we develop an effective first-order and high-resolution space-time discretization of the no-flow surfaces and solve a Lagrangian initial value problem that describes the evolution of the balance laws governing the geometrically intrinsic shallow water equations. The evolved solution set is then projected back to the original surface grid to complete the proposed Lagrangian-Eulerian formulation. The resulting scheme maintains monotonicity and captures shocks without providing excessive numerical dissipation also in the presence of non-autonomous fluxes such as those arising from the geometrically intrinsic shallow water equation on variable topographies. We provide a representative set of numerical examples to illustrate the accuracy and robustness of the proposed Lagrangian-Eulerian formulation for two-dimensional surfaces with general curvatures and discontinuous initial conditions.