Original Shell Research Articles

Improved Polar Current Shell Algorithm for Ocean Current Retrieval from X-Band Radar Data

This paper presents an improved algorithm for retrieving ocean surface currents from X-band marine radar images. The original polar current shell (PCS) method begins with a 3D fast Fourier transform (FFT) of the radar image sequence, followed by the extraction of the dispersion shell from the 3D image spectrum, which is then transformed into a PCS using polar coordinates. Building on this foundation, the improved approach is to analyze all data points corresponding to different wavenumber magnitudes in the PCS domain rather than analyzing each specific wavenumber magnitude separately. In addition, kernel density estimation (KDE) to identify high-density directions, interquartile range filtering to remove outliers, and symmetry-based filtering to further reduce noise by comparing data from opposite directions are also utilized for further improvement. Finally, a single curve fitting is applied to the filtered data rather than conducting multiple curve fittings as in the original method. The algorithm is validated using simulated data and real radar data from both the Decca radar, established in 2008, and the Koden radar, established in 2017. For the 2008 Decca radar data, the improved PCS method reduced the root-mean-square deviation (RMSD) for speed estimation by 0.06 m/s and for direction estimation by 3.8° while improving the correlation coefficients (CCs) for current speed by 0.06 and direction by 0.07 compared to the original PCS method. For the 2017 Koden radar data, the improved PCS method reduced the RMSD for speed by 0.02 m/s and for direction by 4.6°, with CCs being improved for current speed by 0.03 and direction by 0.05 compared to the original PCS method.

MORPHOTYPE MATTERS: AN EXPERIMENTAL ANALYSIS OF THE MORPHOLOGICAL FIDELITY OF GASTROPOD STEINKERNS

Abstract Gastropods are commonly preserved as steinkerns (internal casts), a mode of fossilization that leads to loss of external morphological features. This loss of information is problematic for taxonomic identification and ecological inference in evaluating assemblages where original shell material is not preserved. We seek to quantify how closely gastropod steinkerns represent the morphology of their original shells. We investigated this relationship experimentally by fabricating steinkerns in silicone from modern gastropod shells and comparing their geometry to that of the shells we used to create them. In addition to recording traces of ornamentation such as ribs and spines, we used a theoretical morphospace framework to evaluate the fidelity of shell-coiling parameters in steinkerns. Our results show that some morphotypes reflect their taxonomic identification more accurately than others, indicating that steinkern fidelity is highly variable. Experimental steinkerns consistently cluster less reliably by morphotype than their original shell counterparts. Additionally, we find that shell thickness is an important factor in determining steinkern fidelity. The fidelity of the high-spired Duplicaria duplicata, for example, is significantly lower than the average value for the morphotypes investigated whereas the fidelity of planispiral Haplotrema concavum and open-coiling Epitonium is significantly higher, a trend related to shell thickness. Thus, taxonomic identification and subsequent analyses, such as community composition, of steinkern assemblages must recognize this differential fidelity to counter preservational biases.

Design of Inner Ribs with Unequal Stiffness for Deep-Sea Highly Pressure-Resistant Cylindrical Shells and Utilizing NSGA-2 for Lightweight Optimization

For conducting scientific research at depths in the ocean, deep-sea probes are essential pieces of equipment. The cylindrical shell is the most sensible and rational packaging structure for these detectors. New technical challenges for enhancing the pressure resistance and lightweight design of the pressure-resistant cylindrical shell arise from the need to ensure that the detector packaging structure can withstand the immense water pressure at tens of thousands of meters in the underwater environment, while simultaneously reducing the detector packaging structure’s self-weight. This article examines the detection system’s deep-sea pressure-resistant cylindrical shell. To address the issue of the pressure-resistant shell’s insufficient ability to counteract the overall instability caused by the inability to form unstable half-waves in the radial direction when the ring rib pressure-resistant shell experiences it, a design method for the ribs inside the unequal-stiffness pressure-resistant cylindrical shell is suggested. The shell’s instability pressure increases by 9.65 MPa following the stiffness adjustment. Simultaneously, in order to attain even more lightweight optimization, the optimal inner rib section was obtained by applying the orthogonal topology optimization method, which also reduced the weight by 106.8 g and effectively improved the compression stability of the high-pressure cylindrical shell structure. Based on this, key optimization variables were found by performing sensitivity analysis on the cylindrical shell structure’s parameters. Then, with lightweighting as the primary objective, the high-pressure-resistant cylindrical shell’s optimal structural parameters were found using a multi-objective optimization process using the second-generation fast non-dominated genetic algorithm (NSGA-2). This resulted in a weight reduction of 1.2492 kg, or 17.26% of the original pressure-resistant shell. This has led to the development of a lightweight, highly pressure-resistant method for packaging marine exploration equipment structures.

Overview of the geology, paleontology, and geoscience education opportunities of the University of Tennessee at Martin Coon Creek Science Center for visitors, researchers, and docents

The Coon Creek Formation is an internationally recognized Upper Cretaceous (Campanian, 76 million-years-old) marine clastic lagerstätten deposit with over 500 identified species of nearly perfectly preserved invertebrates, vertebrates, plants, and trace fossils with original shell geochemistry and paleoecological fidelity preserved. The type-locality and type-section, located in rural McNairy County, Tennessee, was preserved for research and education in 1988 when the Memphis Pink Palace Museum constructed a 232-acre geoscience education facility on the site, now run as the University of Tennessee at Martin Coon Creek Science Center. Visitors to the site participate in a wide variety of geoscience education programming and citizen science research that is based upon open-ended inquiry methodology. On the occasion of the 46th Biennial Convention, hosted at the site by the Eta Alpha Chapter of Sigma Gamma Epsilon (SGE), this paper summarizes the overall geologic setting, general paleontology, geoscience education history, and opportunities of the site for SGE field trip participants, potential researchers, visitors, and potential interns. Additionally, this paper highlights some of the numerous geoscience education programs for docents and research opportunities available for geology students who wish to participate in ongoing research at the site.

Lingulid brachiopods with probably preserved original shell colouration from the Kamensk Formation (Moscovian, Middle Pennsylvanian) of the Donets Basin, Ukraine

Lingulid brachiopods with probably preserved original shell colouration from the Kamensk Formation (Moscovian, Middle Pennsylvanian) of the Donets Basin, Ukraine

Stiffening patterns for freeform composite shell structures

This paper investigates innovative approaches for enhancing the structural integrity of form-found shell structures with a focus on rib-based reinforcements. It discusses the significance of ribs in enhancing stability and addressing the sensitivity of form-found structures to various loads. Traditional methods such as increasing shell thickness or introducing supports often compromise efficiency and aesthetics. A more intelligent approach involves reinforcing the shell with ribs and advanced materials. Diverse rib patterns are presented, including geometric, biomimetic, and topological optimization-inspired designs, each adhering to a 50 % volume constraint, when compared to the original shell. Physical testing and numerical simulations demonstrate that these rib patterns significantly increase stiffness and buckling resistance. The findings presented in the paper suggest that combining form-finding methodologies with well-designed rib patterns can create sustainable and resilient structures, contributing to a reduction in both the consumption of materials and the environmental impact of these structures.

Achieving Dendrite-Free and By-Product-Free Aqueous Zn-Ion Battery Anode via Nicotinic Acid Electrolyte Additive with Molecule-Ion Conversion Mechanism.

The widespread adoption of aqueous Zn ion batteries is hindered by the instability of the Zn anode. Herein, an elegant strategy is proposed to enhance the stability of Zn anode by incorporating nicotinic acid (NA), an additive with a unique molecule-ion conversion mechanism, to optimize the anode/electrolyte interface and the typical ZnSO4 electrolyte system. Experimental characterization and theoretical calculations demonstrate that the NA additive preferentially replaces H2O in the original solvation shell and adsorbs onto the Zn anode surface upon conversion from molecule to ion in the electrolyte environment, thereby suppressing side reactions arising from activated H2O decomposition and stochastic growth of Zn dendrites. Simultaneously, such a molecule-to-ion conversion mechanism may induce preferential deposition of Zn along the (002) plane. Benefiting from it, the Zn||Zn symmetric battery cycles stably for 2500h at 1mAcm-2, 1mAhcm-2. More encouragingly, the Zn||AC full batteries and the Zn||AC full batteries using NA electrolyte and Zn||VO2 full batteries also exhibit excellent performance improvements. This work emphasizes the role of variation in the form of additives (especially weak acid-based additives) in fine-tuning the solvation structure and the anode/electrolyte interface, hopefully enhancing the performance of various aqueous metal batteries.

A hierarchic isogeometric hyperelastic solid-shell

The present study aims to develop an original solid-like shell element for large deformation analysis of hyperelastic shell structures in the context of isogeometric analysis (IGA). The presented model includes a new variable to describe the thickness change of the shell and allows for the application of unmodified three-dimensional constitutive laws defined in curvilinear coordinate systems and the analysis of variable thickness shells. In this way, the thickness locking affecting standard solid-shell-like models is cured by enhancing the thickness strain by exploiting a hierarchical approach, allowing linear transversal strains. Furthermore, a patch-wise reduced integration scheme is adopted for computational efficiency reasons and to annihilate shear and membrane locking. In addition, the Mixed-Integration Point (MIP) format is extended to hyperelastic materials to improve the convergence behaviour, hence the efficiency, in Newton iterations. Using benchmark problems, it is shown that the proposed model is reliable and resolves locking issues that were present in the previously published isogeometric solid-shell formulations.

Efficacy and Mechanism of Tetracycline Adsorption by Boron-doped Mesoporous Carbon

Using coconut shell and boric acid as raw materials， a new boron-doped coconut shell mesoporous carbon material （B-CSC） was prepared using a simple one-step pyrolysis method for efficient adsorption and removal of tetracycline pollutants in water. The effects of pyrolysis temperature and boron-carbon mass ratio on the adsorption performance under key preparation conditions were systematically studied， and their microstructure and physicochemical properties were characterized using a specific surface area and pore size analyzer （BET）， field emission scanning electron microscopy （SEM）， X-ray photon spectroscopy （XPS）， Raman spectrometer （Raman）， and Zeta potentiometer （Zeta）. The effects of initial pH， different metal cations， and different background water quality conditions on the adsorption effect were systematically investigated. Combined with material characterization and correlation analysis， the enhanced adsorption mechanism was discussed and analyzed in depth. The results showed that one-step pyrolysis could incorporate boron into the surface and crystal lattice of coconut shell charcoal， resulting in a larger specific surface area and pore volume， and the main forms of boron introduced were H3BO3， B2O3， B， and B4C. The adsorption capacity of B-CSC to tetracycline reached 297.65 mg·g-1， which was 8.9 times that of the original coconut shell mesoporous carbon （CSC）. At the same time， the adsorption capacity of B-CSC for rhodamine B （RhB）， bisphenol A（BPA）， and methylene blue （MB）， common pollutants in aquatic environments， was as high as 372.65， 255.24， and 147.82 mg·g-1， respectively. The adsorption process of B-CSC to tetracycline was dominated by physicochemical interaction， mainly involving liquid film diffusion， surface adsorption， mesoporous and microporous diffusion， and active site adsorption， and H3BO3 was the main adsorption site. The adsorption strengthening mechanism mainly reduced the chemical inertness of the carbon network and enhanced its π-π interaction and hydrogen bonding with tetracycline molecules.

Reaction mechanism of micron-sized aluminum powders in O2 and CO2 gradually heated environment

The behavior of aluminum powders in specific oxidized environment is different from each other obviously. Thermal behaviors of micron-sized aluminum powders in different oxygenated and gradually heating environments were discussed in order to find out the oxidation mechanism. Particular attention is paid to the reaction mechanism of oxygen and carbon dioxide atmosphere. Thermogravimetric analysis and related characterization methods are used and the results demonstrated that under the certain condition, reaction process of micron-sized aluminum powders can be divided into four stages. General routes for the oxidation of micron-sized aluminum in general heating system are the same, however, itis different among the extent of reaction at the third stage in different kinds of oxidizing gas atmospheres. Gas phased products were detected during the main reaction stage under carbon dioxide by combining thermal analysis and mass spectrometry which contributes to the rupture of alumina shell and further reaction of micron-sized aluminum powders. Consequently, rapider and more complete reaction process was achieved. The increasing thickness of original alumina shell can restrict the reaction rate of aluminum powders harder at the same time.

Optimization of the core-shell structures and grain boundary to improve the coercivity of high Ce-content Nd-Ce-Fe-B magnets

The development of Rare-earth iron-boron sintered magnets (RE-Fe-B) based on high-abundance cerium (Ce) is crucial in terms of economic efficiency. In this work, a series of high Ce-content sintered magnets were prepared by incorporating Pr45FebalB (Pr45) into [(PrNd)0.5Ce0.5]29.5FebalB. The further microstructural analysis revealed that the addition of Pr45 alloy resulted in the formation of a thick and widely distributed Pr-rich shell around the Ce-rich grains. Adding Pr45 alloy also significantly suppressed the impurity phase and expanded the diffusion channels of the base magnets. Thus, the coercivity (Hcj) of the base magnets was remarkably enhanced from 5.65 kOe to 9.77 kOe ∼ 16.39 kOe. Subsequently, the grain boundary diffusion of dysprosium hydride (DyHx) powders was carried out in the optimized base magnets. Results of microstructural analysis showed that the matrix phase grains formed a dual-shell structure comprising a Dy-rich shell in addition to the original Pr-rich shell, thereby enhancing the anisotropic field of the matrix phase grains. The increment in Hcj of the diffused magnets ranged from 3.03 kOe to 5.36 kOe (the original unoptimized diffusion magnet coercivity was only 1.69 kOe). This work provides a novel solution for preparing high-coercivity Nd-Ce-Fe-B sintered magnets.

Hybrid Visualization with Vulkan-OpenGL: Technology and Methods of Implementation in Virtual Environment Systems

In this paper, the topic of integrating visualization tasks to be solved using the Vulkan API into virtual environment systems based on OpenGL visualization, is researched. The problem of Vulkan-OpenGL hybrid visualization and an approach to its solution, based on a modified render-to-texture technique, are described. The technology of constructing an original embeddable program shell (VK-capsule) is proposed, which allows hybrid visualization as a "black box" to be worked with, obtaining an image in the OpenGL frame buffer at the output. The paper presents the developed structure of the VK-capsule, comprising three program blocks (VK-, GL- and I-block), and describes methods and algorithms for their construction. Based on proposed technology, methods and algorithms, a VK-capsule for height field visualization task was developed, which utilizes hardware-accelerated ray tracing, Vulkan API supported by. The approbation of the developed VK-capsule was carried out, which showed that proposed solutions are effective and meet the task. The results obtained can be used in virtual environment systems, scientific visualization, video simulators, virtual laboratories, educational applications, etc.

Creep of Concrete in Shell Structures: Nonlinear Theory.

The creep of concrete is one of the main problems threatening concrete structural development and the stability and safety of structures. However, the nonlinear theory is the key to solving the problem of taking into account the physical and mechanical properties of concrete creep in shell structures. To create such a theory, the original shell is replaced by a continuous equivalent elastic shell. To determine the stress-strain state of the structure, the equations of nonlinear creep and crack growth are derived, and a deformation model of the section is created. The behavior of the structure at all stages of the life cycle is investigated by solving the solving systems of differential equations of equilibrium, motion, and perturbation of the equivalent shell. The values of the ratios of dependence of long-term and short-term critical loads on deformations, forces, cracks, etc., are given. The accuracy of the solution of the developed nonlinear theory is compared with the linear theory of concrete creep as well as experimental data. The results show that, according to the linear theory, for the values for the short term and long term, up to 56% and up to 39% of critical loads are overestimated, respectively. The creep process in practical engineering can be effectively controlled by the results of the proposed theory.

The first record of a Konservat-Lagerstätten in which early post-settlement stages of fossil archaeobalanids (Cirripedia: Balanomorpha) are preserved.

A diverse sessile barnacle fauna from a Miocene shallow-water deposit at Dolnja Stara vas in Slovenia is described. It includes the first descriptions of early post settlement juveniles of Actinobalanus sloveniensis attached to mangrove leaves. These represent three distinct growth phases, the earliest being interpreted as being less than 24 h post settlement, the others being 1 to 2 days post settlement. An assessment of their taphonomy is provided. Associated adult balanomorphs are attached to a variety of organic substrates, including mangrove leaves and branches, fragments of the conifers ?Taxodioxylon, Carapoxylon, pine cones, molluscs, and cetacean bones. The barnacles include A. sloveniensis, Amphibalanus venustus, and Perforatus perforatus-many with opercula retained within the shells. A. venustus retains some of the original shell color. This is the second record of barnacle-plant associations from the Central Paratethys from Kamnik and Trbovlje. The paleoecology and paleogeography of the site are discussed.

Foraminifera associated with cold seeps in marine sediments

Cold seep foraminifera have attracted considerable attention as they provide valuable insights into the study of cold seeps. This study provides a comprehensive overview of the manifestations of foraminifera in cold seep environments and methane seepage activities. Certain taxa of benthic foraminifera, such as Uvigerina, Bolivina, Bulimina, Chilostomella, Globobulimina, Nonionella, Melonis, Epistominella, Cibicidoides, and Globocassidulina, are known to inhabit geochemical conditions induced by methane-rich environments and may feed on associated methanotrophic microbial communities. Secondary mineralization on foraminifera shells is a widespread manifestation in seep sediments, and alters the microstructure, elementary composition, and isotopic signatures of foraminifera. On one hand, the precipitation of secondary authigenic Mg-rich, Mn-rich, Sr-rich, and Ba-rich calcite coatings have been observed on microfossils. On the other hand, micron-sized crystal pyrite and gypsum aggregates can also grow on the foraminifera walls. The negative δ13C and positive δ18O anomalies in both planktonic and benthic foraminifera from seep-associated sediments can serve as proxies for tracing past seepage activities, either in their live form or being adulterated by methane-derived authigenic carbonate after deposition. Seeping activities are recognized with a significant impact on benthic foraminifera, and the presence of cold seep-related species and significant isotopic anomalies in shells can be used to reconstruct past methane seepage events. Intensive methane seepage tends to suppress benthic foraminifera populations, while moderate intensity seepage may lead to a thriving benthic foraminiferal community, with hypoxia-enduring taxa such as Uvigerina, Melonis, and Bulimina being predominant. In contrast, oxygen-loving epibenthic taxa such as Cibicidoides often occur in areas of low methane flux. Compared to planktonic foraminifera, the single species of benthic foraminifera can provide a more comprehensive record of seepage evolution. Live benthic specimens are preferred for in-situ seep studies, while the superimposition of secondary minerals on the original shells should not be ignored when observing dead individuals. The significance of the evolution of methane seepage, changes in environmental parameters of the living habitat, and species sensitivity in cold seeps are emphasized in explaining the variation in foraminiferal assemblages and fluctuations in stable isotopes.

Re-Examination of the Polymer Encapsulation of Quantum Dots for Biological Applications

The application of semiconductor core–shell quantum dots in biology requires the dispersion of these nanoparticles in water. A widely used phase transfer strategy is their encapsulation with amphiphilic polymers, a method that is believed to preserve the original ligand shell of quantum dots. In this contribution, we test this belief for the first time using a common encapsulation protocol based on poly(styrene-co-maleic anhydride) and ethanolamine and demonstrate that the original quantum dot ligand shell is in fact altered during the polymer encapsulation. In particular, our results show that primary amines, which are typically added to increase the hydrophilicity of the encapsulating polymer, displace the original ligands as a necessary step in the phase transfer process. We demonstrate that the surface of quantum dots synthesized using phosphinic acid as a ligand is readily modified by ethanolamine and hence shows high phase transfer efficiency, whereas quantum dots synthesized using oleic acid ligands did not show reactivity toward the primary amine and failed to transfer in the same conditions. Instead, a thiol, mercaptoethanol, was employed to displace the original oleic acid ligands and promote efficient poly(styrene-co-maleic anhydride) encapsulation. This work also provides practical guidelines for how the quantum dot community can better design and implement phase transfer protocols for a given composition, in order to maximize the efficiency and durability of the resulting water-dispersible nanoparticles for biological applications.

DEVELOPMENT OF MICROCAPSULES BASED ON COMBINED ANTIDIABETIC SUBSTANCE: PHARMACOLOGICAL CHARACTERISTICS

The comparative assessment results of the hypoglycemic activity of a combined preparation containing microcapsules with a phytocomposition consisting of Glycyrrhiza glabra L. extracts, a dry extract of Galega officinalis L., Mentha piperita L., and gliclazide, are discussed in the article. Methods for obtaining microcapsules with an original PEG-6000 shell are described.The aim of the study was to develop an optimal technology for obtaining microcapsules with a PEG-6000 shell containing a combined antidiabetic substance, and conduct its detailed pharmacological study on the model of type 2 diabetes mellitus, to conduct a detailed comparative pharmacological study of a microencapsulated antidiabetic composition with a shell based on PEG-6000, including gliclazide and a sum of phytoextracts on the model of type 2 diabetes mellitus.Materials and methods. As the main objects of the study, microcapsules with a PEG-6000 shell were obtained using methyl miristate as the base liquid. The capsules contained the amount of plant extracts in their composition: a dry extract of Glycyrrhiza glabra L., a dry extract of Galega officinalis L., a dry extract of Mentha piperita L., and gliclazide. The study of a hypoglycemic activity was carried out after a single administration of drugs to the animals with alloxan-induced type 2 diabetes mellitus. The cumulative effect assessment of the drugs was carried out within 14 days with a test for the resistance to oral glucose on days 7 and 14.Results. Microcapsules with the original shell were obtained by dispersion in a liquid-liquid system with the adjustment of some technological stages. The effect of the drugs under study on the glycemic profile in the rats with an experimental model of type 2 diabetes mellitus was investigated. A comparative evaluation of the pharmacological effect was carried out with a separate and combined use of microencapsulated preparations.Conclusion. The rationality of combining phytocomponents and a synthetic antidiabetic agent in microcapsules has been proven. The obtained results testify to the rationality of plant extracts combination and a synthetic hypoglycemic agent – gliclazide in microcapsules.

Heterogeneous selective ensemble learning model for mill load parameters forecasting by using multiscale mechanical frequency spectrum

A ball mill is a heavy mechanical device and its safe operation affects the entire grinding process. Mill load is a key index in the optimum operation of the grinding process, but it cannot be measured directly. In industrial practice, operational experts normally estimate its value based on their experiences and the mechanical signals produced by the ball mill. In this paper, we proposed a heterogeneous selective ensemble method by using a multiscale mechanical frequency spectrum. The multicomponent adaptive decomposition algorithm is first used to decompose the original shell vibration and acoustic signals into sub-signals with different timescales. Then, selective ensemble (SEN) kernel projection to latent structure algorithm is used to model the spectral data of these sub-signals. Furthermore, the latent features of multiscale spectra are extracted to construct SEN models based on fuzzy inference. Finally, the two types of heterogeneous SEN models are fused by using information entropy. The main contribution of this study is that the proposed soft-sensing model has a dual-layer ensemble structure that can fuse multi-source information in different mechanical sub-signals with physical meaning. Moreover, the proposed model can simulate the fuzzy cognitive behavior of domain experts in the mineral grinding process. The effectiveness of the method is verified by the shell vibration and acoustical data of a laboratory-scale ball mill.

Automatic left atrial segmentation from cardiac CT using computer graphics imaging and deep learning

Abstract Introduction Segmenting left atrial (LA) substructures, including the LA body, appendage (LAA), and pulmonary veins (PVs), from computed tomography (CT) is central to electroanatomic mapping for ablation and functional studies in patients with atrial fibrillation (AF). However, this process requires manual outlining which needs special training, is subjective, and is difficult to scale. Computer graphics imaging (CGI) has been applied in media, film, and computer-aided design to reliably segment complex structures using their basic geometric representations. Purpose We hypothesized that LA substructures can be “virtually” dissected using CGI to separate geometric contours of the “convex ellipsoid” LA, “tubular” PVs, and “conical” LAA. We further hypothesized that the results of virtual dissection can be used to train a deep learning (DL) model to segment raw CT scans. Methods First, a mathematical method based on CGI techniques – erosion and dilation – was developed to “virtually dissect” the convex LA body from the original concave shell in publicly available digital atria with diverse simulated morphologies (Fig. 1A). The PVs and LAA were then automatically revealed and labeled by a 3D subtraction approach. Second, we refined precise LA/PV/LAA boundaries by tuning hyper-parameters from N=5 patient shells (Fig. 1B). Third, we used virtual dissection to train a DL model to segment CTs in N=20 patient atria (Fig. 1C). Finally, we applied this pipeline to segment raw CTs in a validation cohort of N=105 patients (23.8% women, 63.8±10.3Y; Fig. 1D). Results Virtual dissection accurately identified LA/PV/LAA boundaries in the training set (Dice coefficients 89–98%). In the independent test cohort (N=105), this automated pipeline accurately segmented raw CTs with Dice 81–95% (Fig. 1D) compared to a panel of experts (p<0.001). Conclusion CGI of basic cardiac geometry combined with deep learning in small datasets can accurately segment raw CT scans in large populations. This computational pipeline may automate and simplify cardiac image processing and ablation procedures, and could be applied to the ventricle or other organ systems for diverse therapeutic strategies or to train machine learning. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Institutes of Health

Palaeoecological implications of stable isotope analyses of late Valanginian ammonites from central Poland

Analyses of δ18O and δ13C of original shells of late Valanginian (verrucosum to triptychoides ammonite zones) ammonites preserved in clay at localities in central Poland, and of some Berriasian samples from well cores have been carried out for the first time. Analyses of carbon stable isotope composition have revealed diverse values, representing vital effects rather than recording the palaeoenvironment. In turn, analyses of oxygen stable isotope composition in samples from the verrucosum and triptychoides ammonite zones clearly indicates the connection between particular species and stable isotope ratios, and thus palaeotemperature. The interpretation of ammonite palaeoecology in the present paper is based on estimated palaeotemperatures and supports other interpretations of ammonite behaviour, mainly based on functional morphology of shells. There are two main groups of ammonites associated with lower and higher temperatures. The first group of δ18 O values indicates lower palaeotemperatures. Genera analysed include Bochianites, Dichotomites and Prodichotomites; a nekto-benthic (demersal) habitat is suggested for these. The second group, characterised by higher palaeotemperatures, includes Saynoceras, Valanginites and Olcostephanus, with a suggested nektonic (or planktic) habitat (free-floating), Neohoploceras and Neocomites with a suggested nektonic habitat (free-swimming) and a seasonal migration from warmer (Tethys) to cooler waters of the Polish Basin or lived in the Polish Basin for several summer and winter seasons. Co-occurring bivalves, echinoid spines and scaphopods were analysed for comparison with results obtained from ammonites for a better overview of the palaeoenvironment. The estimated palaeotemperatures for the Polish Basin are between 12 and 13 °C (at the sea floor) to 21–24 °C (in the upper water column), while for the Tethys or summer surface waters of the Polish basin, these were in the range of 26–30 °C.