Continuous Section Research Articles

Additive manufacturing of continuous wave and pulsed wave L-PBF Ti64 thin cross sections

Additive manufacturing of continuous wave and pulsed wave L-PBF Ti64 thin cross sections

Enhanced measurement and optimization of railway profile parameters for large tamping machine operations

Abstract In the realm of modern railway maintenance, the employment of large tamping machine for the enhancement of track geometry and elasticity, and the minimization of disturbance to the roadbed, has become a key operational approach. However, factors such as repeated load applications, changes in topography and geology, and ongoing maintenance activities have been known to cause significant deviations of the actual track location from its original design. These deviations present challenges, such as increased construction difficulty and workload, during tamping operations predicated on the original design. Moreover, methods based on manual intervention have rendered large machine maintenance operations inefficient. In this paper, an optimisation method for railway profile parameters suitable for large tamping machine operations is proposed. The method integrates the total least squares method and the direct search method, enabling the accurate fitting of slope segments preceding and following the slope change points and the alignment of circular curve segments to determine the optimal curve radius. Consequently, optimised profile parameters for the continuous track section are obtained. Focusing on the Beijing–Guangzhou line, the operational efficacy of the proposed optimisation method is compared with that of the artificial slope method. The results showed that the proposed optimisation method is not only more accurate and efficient but also adheres to the principle of ‘prefer lifting rather than descending’ of the railways. The method further provides a theoretical basis and practical guidance for the optimisation of railway profile, underscoring the potential for improved maintenance efficiency and enhanced safety in train operations.

Features of Consistent Powassan Virus Lineage II Focus in Southern Maine, United States.

Powassan virus lineage II or deer tick virus (DTV) is a rare but increasingly reported human infection in the United States transmitted by Ixodes scapularis ticks. The virus is thought to be maintained in environmental foci that are optimal for tick and vertebrate reservoirs, but details on DTV ecology are poorly understood. We investigated DTV tick infection rates and reservoir host abundance in a focus of consistent DTV activity in Maine, USA. Host and tick abundance, vegetation, and microclimate conditions were measured in three forest sites representing increasing invasive understory infestation. Sites were selected representing native understory, mixed vegetation with some invasive Japanese barberry (Berberis thunbergii), and a highly invasive site dominated by Japanese barberry. Japanese barberry in the mixed vegetation site averaged 1 m in height with space between plants, whereas the highly invasive site had impenetrable Japanese barberry over 1.5 m. The DTV infection rate was greater in the highly invasive site. Density of I. scapularis ticks were significantly lower in the native forest site, and no DTV was found. Another feature of the DTV focus was more stable humid microclimate throughout the year compared with the other sites and a nearby continuous section of forest, consistent with reports from Connecticut, USA. We conclude that invasive Japanese barberry stands provide favorable and consistent microclimate conditions to maintain high DTV infection rates annually among questing I. scapularis ticks. Understanding environmental and landscape features that support high infection rates could lead to the identification of high-risk habitats for contracting DTV.

Managing a potential conflict between the protection of geological sites and the need to safeguard essential road infrastructure: the Coverack North Coast Protection Scheme and palaeo-Moho in Cornwall, UK

In alignment with the Cornwall & Isles of Scilly Shoreline Management Plan (SMP2), adopted by Cornwall Council, the Coverack North Coast Protection Scheme comprised the construction of a circa 125m long rock armour revetment, and 55m long retaining wall, at Coverack Cove on the Lizard peninsula in Cornwall, UK. This was to prevent sea erosion impacting vehicle access via the B3294, the main public highway into Coverack. The site of the proposed works on Coverack Beach is part of a Natural England designated Site of Special Scientific Interest (SSSI) for its geology, specifically the exposure on the foreshore of an almost continuous cross section of a palaeo-Moho, the former boundary between the earth's crust and underlying mantle. Following a period of consultation, a set of management proposals and mitigation measures were agreed with Natural England and Cornwall Council to protect and offset the impact of the proposed works on the SSSI asset. It is sometimes difficult to reconcile the issue of protecting communities from coastal erosion and ensuring the protection of geological assets. This can be mitigated if a balanced approach is adopted, and the work is sensitively managed to offset the impact of coastal protection schemes such of this.

Deep learning-based hyperspectral technique identifies metastatic lymph nodes in oral squamous cell carcinoma-A pilot study.

To establish a system based on hyperspectral imaging and deep learning for the detection of cancer cells in metastatic lymph nodes. The continuous sections of metastatic lymph nodes from 45 oral squamous cell carcinoma (OSCC) patients were collected. An improved ResUNet algorithm was established for deep learning to analyze the spectral curve differences between cancer cells and lymphocytes, and that between tumor tissue and normal tissue. It was found that cancer cells, lymphocytes, and erythrocytes in the metastatic lymph nodes could be distinguished basing hyperspectral image, with overall accuracy (OA) as 87.30% and average accuracy (AA) as 85.46%. Cancerous area could be recognized by hyperspectral image and deep learning, and the average intersection over union (IOU) and accuracy were 0.6253 and 0.7692, respectively. This study indicated that deep learning-based hyperspectral techniques can identify tumor tissue in OSCC metastatic lymph nodes, achieving high accuracy of pathological diagnosis, high work efficiency, and reducing work burden. But these are preliminary results limited to a small sample.

Analysis of tumor regression after concurrent radiochemotherapy for locally advanced hypopharyngeal carcinoma

Objective: To investigate the pathological characteristics of tumor regression and the expression level of chemoradiotherapy resistance-related molecular markers after preoperative concurrent radiochemotherapy in patients with locally advanced hypopharyngeal carcinoma. Methods: The clinical data of 44 patients with locally advanced hypopharyngeal carcinoma who underwent preoperative concurrent radiochemotherapy in the Department of Head and Neck Surgery of Shandong Otolaryngology Hospital from August 2016 to August 2020 were retrospectively analyzed. All patients received preoperative concurrent chemotherapy and radiotherapy. After radiochemotherapy, electronic laryngoscopy and imaging examination were performed to assess the tumor regression status. After 4 weeks, surgical resection was performed, and the specimens of the primary focus were processed as continuous pathological sections. After operation, HE staining and TdT-mediated dUTP nick-end labeling (TUNEL) method were used to detect the distribution characteristics and apoptosis of the remaining cancer focus, and immunohistochemistry was performed to determine the proliferation of the remaining cancer focus and the expression of radiation resistance-related molecular markers [signal transducer and activator of transcription 3 (STAT3), hypoxia-inducible factor-1alpha (HIF-1α), sex determining region Y-box 2 (SOX2), and P53]. Results: A total of 44 patients were included, all of whom were male, with a mean age of (58.3±3.5) years. There were 40 cases of pyriform sinus carcinoma and 4 cases of posterior pharyngeal wall carcinoma. Twenty-nine cases were in stage T3 and 15 cases were in stage T4. There were 6 stage Ⅲ cases and 38 stage Ⅳ cases. According to the response evaluation criteria in solid tumors (RECIST), 13 patients achieved complete response (CR), 22 patients had partial response (PR), and 9 patients achieved stable disease (SD) after concurrent radiochemotherapy. The primary lesion resection methods included 19 cases of hypopharyngeal circumferential resection and 2 cases of total laryngectomy and partial hypopharyngeal resection. Twenty-three cases underwent supracricoid cartilage subtotal laryngectomy cricoid tongue fixation (CHP). Among 22 patients with PR, 10 had large PR (remission rate ≥70%) and 12 had small PR (remission rate <70%). The residual tumor was found in 30 patients (68.2%) after resection of all primary lesions by HE staining of pathological sections, of which 3 patients (3/13) with CR had residual cancer, all of which were focal residues. In large PR patients, residual cancer was detected in 6 cases (6/10), scattered in 4 cases, and focal residual in 2 cases, respectively. Large residual tumors were detected in small PR and SD patients. TUNEL method did not show any sign of apoptosis in 30 specimens with residual cancer focus, and the positive expression rate of Ki-67 was less than 10%. The expression of STAT3 (3.40±2.49 vs 5.23±3.02, t=-2.932, P=0.007) in 19 cases (63.3%) and HIF-1α (3.73±2.66 vs 6.97±3.05, t=-4.45, P<0.001) in 22 cases (73.3%) of residual cancer were significantly higher than those before radiochemotherapy. Other molecular markers showed no significant changes. All patients were followed up for 3 years. The 2-year survival rate was 59.3%, and the 3-year survival rate was 54.1%. Conclusions: Preoperative radiochemotherapy can make some patients with locally advanced hypopharyngeal carcinoma achieve complete or significant remission in clinical evaluation, but pathological detection still shows some residual cancer lesions with enhanced anti-apoptosis ability and decreased proliferation activity.

Actinopterygians from the continental Permian–Triassic boundary section at Babiy Kamen (Kuznetsk Basin, Siberia, Russia)

The Kuznetsk Basin in Siberia (Russia) is an important area for the study of the continental biota of late Permian to Early Triassic in continuous sections. This study presents a taxonomic description of ray-finned fishes (other fish remains are absent at the section) from the Permian–Triassic boundary section at Babiy Kamen. The new material was collected, bed by bed, during geological and paleontological excavations of coastal-floodplain, shallow-basin deposits of the Tailugan and Maltseva formations. The poorly preserved but diverse ichthyofaunal fossils of the Tailugan Formation consists predominantly of typical Late Paleozoic “palaeoniscoid” fishes (Eurynotoidiidae, Varialepididae, etc.). The earliest known Triassic (Induan) Kedrovo Member of the Maltseva Formation contained a less diverse but well preserved ichthyofaunal fossils including “palaeoniscoid” fishes (Korutichthys and Avamia). The same species were described earlier from the Induan of the Tunguska Basin. The ichthyofauna of the Early Triassic (Olenekian) Ryaboy Kamen Member of the Maltseva Formation consists of typical Triassic stem-neopterygian (Evenkia, Eoperleidus and Arctosomus) fishes. The same fishes have been described earlier from the Olenekian of Tunguska Basin. The composition of the ichthyofauna completely changed twice — at the Permian–Triassic and the Induan–Olenekian boundaries.

A revision of the Carnian/Norian boundary radiolarian assemblages: Insight from the biostratigraphic record of the Norian GSSP, Pizzo Mondello section (Sicily, Italy)

The Triassic was a critical period for a significant increase in the generic diversity of radiolarians after the disappearance of >80% of radiolarian genera during the Permian-Triassic mass extinction. In particular, the Upper Triassic radiolarian fauna is rich and has been documented in several world regions, such as North America, Western Europe, the Mediterranean area, Japan, the Philippines, Timor, and Far East Russia. In this study, a well-preserved and high-diversity fauna from a continuous pelagic-hemipelagic section deposited in western Tethys (Sicily, Italy) provides one of the most detailed radiolarian records of the Carnian-Norian boundary interval, which can be correlated worldwide, from high to low-latitude, from both sides of the Pangea and both Hemispheres. The 99 species belonging to 50 genera from this time interval have been collected from the Pizzo Mondello section (Sicanian Basin, Western Sicily), the selected GSSP for the base of the Norian stage, and then compared to the radiolarian associations documented in other coeval regions. Based on the occurrences of characteristic radiolarian species, we defined and proposed a new radiolarian biozonation across the Carnian-Norian boundary, which consists of five new assemblages (PM assemblage 1–5) that are correlated and calibrated to the already well-defined biozonation of bivalves, ammonoids, and conodonts.

Design and Effect Evaluation of a Hydrogen–Natural Gas Mixing Device at Jingbian Compressor Station

Abstract Hydrogen gas is an environmentally friendly alternative energy source with zero emissions, making it highly valuable for replacing fossil fuels and reducing carbon emissions. One effective method of transporting hydrogen gas is by injecting it into existing natural gas pipelines. In this research, we focus on the Jingbian compressor station. This station is used for hydrogenation, blending hydrogen with the natural gas flowing through the pipelines. We propose a suitable process for hydrogen blending and design a mixing device to facilitate this process. To evaluate the mixing effect of the blended gas, we conducted numerical simulations to analyze the velocity and concentration distribution along the continuous section of the hydrogen blending pipeline. The results indicated that achieving a hydrogen branch length of 1/2 the diameter of the natural gas main pipe and a hydrogen flowrate of 10% resulted in a nonuniformity of hydrogen concentration at L = 30D of less than 0.05. Furthermore, when the hydrogen concentration was set at 3%, 10%, and 30%, the hydrogen concentration in the cross section of the pipe gradually approached the expected concentration as the mixed gas flowed. It is worth noting that during transportation of hydrogen-containing natural gas to the outlet, the velocity distribution on the cross section remained asymmetric, potentially leading to measurement errors. However, the use of a flow conditioner resulted in a further reduction in hydrogen nonuniformity and minimized velocity fluctuations, resulting in a small and uniformly distributed flow, which is advantageous for accurate measurement and transportation purposes.

Continuity of inner-outer factorization and cross sections from invariant subspaces to inner functions

Let H∞ be the Banach algebra of bounded analytic functions on the unit open disc D equipped with the supremum norm. As well known, inner functions play an important role in the study of bounded analytic functions. In this paper, we are interested in the study of inner functions. Following by the canonical inner-outer factorization decomposition, define Qinn and Qout the maps from H∞ to I the set of inner functions and F the set of outer functions, respectively. In this paper, we study the H2-norm continuity and H∞-norm discontinuity of Qinn and Qout on some subsets of H∞. On the other hand, the Beurling theorem connects inner functions and invariant subspaces of the multiplication operator Mz. We show the nonexistence of continuous cross section from some certain invariant subspaces to inner functions in the supremum norm. The continuity problem of Qinn and Qout on Hol(D‾), the set of all analytic functions in the closed unit disk, are considered. In addition, we also study the factor maps Q[inn] and Q[out] from H∞ to I/T and F/T, where I/T is the quotient space of I mod T and F/T is the quotient space of F mod T.

Abstract 2035: In-Depth Analysis Of Tibial Artery Calcification Through Microct And Histology

Background: Peripheral artery disease (PAD) impacts over 200 million people worldwide. It is traditionally linked to atherosclerotic calcification, or intima arterial calcification (IAC). Recent findings emphasize the role of medial arterial calcification (MAC). Current studies have identified some factors in MAC and IAC, however, a comprehensive understanding of their distinct features and pathogenesis is lacking. This study addresses this gap by examining tibial arteries from PAD patients post-amputation. We characterized the calcification using microCT and histology. Methods: Human tibial arteries were obtained from PAD patients post amputation, and segmented into posterior, anterior, and peroneal arteries. The arteries were dissected, fixed in 4% paraformaldehyde, and stained with iodine. High-resolution microCT images were captured using a Scanco μCT40, and 3D models were reconstructed by ImageJ and Slicer3D. The samples were then processed for histological analysis, including Hematoxylin and eosin (H&amp;E) stain and Alizarin red staining. Results: The study design is shown in Fig. A, featuring the serial dissection of a posterior artery as an example. The microCT scan protocol is designed for imaging continuous sections under a specific orientation. The 3D models enable a comprehensive assessment of calcification and quantification for distinct categorization, and the peroneal artery showed the least calcified lesions (*P&lt;0.05, ***P&lt;0.001; Fig. B &amp; C). MAC/IAC or co-existing lesions were characterized by cross-sectional images and H&amp;E staining. The results indicated a predominance of MAC in the highly calcified group, comprising over 98% of the entire tissue (Fig. D &amp; E). Conclusions: We characterized calcified lesions in tibial arteries by microCT and histology. Calcification categories were determined through 3D models. Histology and cross-section images enabled the assessment and quantification of MAC/IAC or co-existing lesions.

Recent Developments in Using a Modified Transfer Matrix Method for an Automotive Exhaust Muffler Design Based on Computation Fluid Dynamics in 3D

The present work aims to investigate the newly modified transfer matrix method (MTMM) to predict an automotive exhaust muffler’s transmission loss (AEMTL). The MTMM is a mixed method between a 3D-CFD (Computation Fluid Dynamics in 3D), namely AVL FIRETM M Engine (process-safe 3D-CFD Simulations of Internal Combustions Engines), and the classic TMM for the exhaust muffler. For all the continuous and discontinuous sections of the exhaust muffler, the Mach number of the cross-section, the temperature, and the type of discontinuity of the exhaust gas flow were taken into consideration to evaluate the specific elements of the acoustic quadrupole that define the MTMM coupled with AVL FIRETM M Engine for one given muffler exhaust. Also, the perforations of intermediary ducts were considered in the new MTMM (AVL FIRETM M Engine linked with TMM) to predict the TL (transmission loss) of an automotive exhaust muffler with three expansion chambers. The results obtained for the TL in the frequency range 0.1-4 kHz agree with the experimental results published in the literature. The TMM was improved by adding the AVL FIRETM M Engine as a valuable tool in designing the automotive exhaust muffler (AEM).

Partial actions of groups on profinite spaces

We show that for a partial action η with closed domain of a compact group G on a profinite space X the space of orbits X/~G is profinite, this leads to the fact that when G is profinite the enveloping space XG is also profinite. Moreover, we provide conditions for the induced quotient map πG : X → X / ∼G of η to have a continuous section. Relations between continuous sections of πG and continuous sections of the quotient map induced by the enveloping action of η are also considered. At the end of this work, we prove that the category of actions on profinite spaces with countable number of clopen sets is reflective in the category of actions of compact Hausdorff spaces having countable number of clopen sets.

Penyelesaian khusus persamaan diferensial biasa ordo dua linier tak homogen dengan koefisien konstan untuk fungsi bagian demi bagian

Spring mechanical vibration motion system with a damped degree of freedom and influenced by external forces, is mathematically expressed as an ordinary differential equation of order of two linear constant coefficients that are not homogeneous. If an external force acts on a stationary system expressed as a continuous function f(t) for any time t, then the system will experience mechanical vibrational motion which mathematically the equation of motion can be expressed as a superposition. The equation consists of as a solution to a homogeneous form with mechanical vibrations as a solution to a particular form. In terms of the particular solution this article will show a mathematical way when f(t) is a continuous function section by part which is defined at an interval, such that the mechanical vibration motion equation is at the same time a special solution of the equation the mechanical vibration system.&#x0D; Keywords: Vibration, Impulse Functions, ConvolutionMSC2020: 34A37

The Barremian–lower Aptian of NE Arabia: The Kharaib and Shu'aiba formations in Wadi Rahabah and Wadi Kebdah, Ras Al Khaimah, U.A.E.

We present a high-resolution record of carbonate depositional facies, biostratigraphy, stable-isotope and elemental geochemistry of the Kharaib and Shu'aiba formations exposed in Ras Al Khaimah, northern UAE. This is the first comprehensive study of these deposits in the northeastern Arabian Peninsula, which have previously been studied extensively in Abu Dhabi, Oman, NE Saudi Arabia, and southwestern Iran, and represents the most detailed biostratigraphic and chemostratigraphic record currently available from a continuous outcrop section of the Arabian Plate. The Barremian–Aptian boundary was approximated based on orbitolinid biostratigraphy, while a subdivision of the Barremain was not possible. There is no biostratigraphic evidence that the Shu'aiba Formation in the section studied ranges into the upper Aptian. Previously well-established depositional sequences of the Barremian–lower Aptian of the Arabian Plate are discussed in the context of carbonate textures, siliciclastic influx, and biotic assemblages. There is a general trend of decreasing siliciclastic components during the Barremian and earliest Aptian, and peaks in siliciclastic influx indicate episodes of maximum accommodation. Palaeogeographic implications of our data for the distribution of intrashelf basins and their connection to Neotethys are discussed. The negative carbon-isotope excursion that globally marks the onset of OAE1a is not evident in our dataset, while the positive excursion at the end of OAE1a is present in the late early Aptian. A comparison of carbon-isotope records across the early Aptian of the Arabian Plate highlights issues of correlations that are predominantly based on chemostratography in diagenetically altered platform carbonates.

Marine Strontium Isotope Evolution at the Triassic‐Jurassic Transition Links Transient Changes in Continental Weathering to Volcanism of the Central Atlantic Magmatic Province

AbstractThe end‐Triassic extinction (ETE) is one of the most severe biotic crises in the Phanerozoic. This event was synchronous with volcanism of the Central Atlantic Magmatic Province (CAMP), the ultimate cause of the extinction and related environmental perturbations. However, the continental weathering response to CAMP‐induced warming remains poorly constrained. Strontium isotope stratigraphy is a powerful correlation tool that can also provide insights into the changes in weathering regime, but the scarcity of 87Sr/86Sr data across the Triassic‐Jurassic boundary (TJB) hindered the use of this method. Here we present new high‐resolution 87Sr/86Sr data from bulk carbonates at Csővár, a continuous marine section that spans 2.5 Myrs across the TJB. We document a continuing decrease in 87Sr/86Sr ratio from the late Rhaetian to the ETE, terminated by a 300 kyr interval of a flat trend and followed by a transient increase in the early Hettangian that levels off. We suggest that the first in the series of perturbations is linked to the influx of non‐radiogenic Sr from the weathering of freshly erupted CAMP basalts, leading to a delay in the radiogenic continental weathering response. The subsequent rise in 87Sr/86Sr after the TJB is explained by intensified continental crustal weathering from elevated CO2 levels and reduced mantle‐derived Sr flux. Using Sr flux modeling, we also find support for such multiphase, prolonged continental weathering scenarios. Aggregating the new data set with published records employing an astrochronological age model results in a highly resolved Sr isotope reference curve for an 8.5 Myr interval around the TJB.

The Cretaceous deposits of the Paris Basin

Abstract Since the creation of the Cretaceous system by Jean-Baptiste d'Omalius d'Halloy, numerous analyses have provided details about the Cretaceous sedimentary successions of the Paris Basin, where many boreholes have been drilled. We present a synthesis of the Cretaceous deposits using data from recent drilling carried out in the central and eastern parts of the basin which, during the early Cretaceous, corresponded to a continental environment represented by Wealden facies. However, from the Berriasian to the Barremian, the southeastern part of the basin was occasionally invaded by a shallow sea during transgressions originating from the Tethys Ocean. The sedimentary successions of this age presented in this article have been studied thanks to drilling carried out by Andra (French Agency for Nuclear Waste Disposal). Several new results are presented here: a discussion on the age of the Argiles ostréennes, the identification of an equivalent of oceanic anoxic event (OAE)1a, and the construction of a continuous section of the Albian clays in their type area. Regarding the Upper Cretaceous chalk, the Cenomanian to Maastrichtian stages are represented over the entire basin and correlations are proposed based on biostratigraphic data and various marker beds including marly levels, bentonites, hardgrounds and eco-events.

Three-dimensional model of normal human dermal tissue using serial tissue sections.

Background: This study aims to construct a three-dimensional model of skin dermis utilizing continuous tissue sections, with the primary objective of obtaining anatomical structure data for normal human dermal tissues. Methods: Normal skin tissue specimens were acquired, paraffin-embedded, and subjected to HE staining. Panoramic images of skin sections were captured using a microscope. Tissue section images were aligned using the SIFT and StackReg image alignment methods, with analysis conducted using the OpenCV module. Mimics17 software facilitated the reconstruction of the skin dermal 3D model, enabling the calculation of dermal porosity and the void diameter. Results: Panoramic skin slices exhibited high-resolution differentiation of dermal fibers and cellular structures. Both SIFT and StackReg image alignment methods yielded similar results, although the SIFT method demonstrated greater robustness. Successful reconstruction of the three-dimensional dermal structure was achieved. Quantitative analysis revealed a dermal porosity of 18.96 ± 4.41% and an average pore diameter of 219.29 ± 34.27 μm. Interestingly, the porosity of the dermis exhibited a gradual increase from the papillary layer to the fourth layer, followed by a transient decrease and then a gradual increase. The distribution of the mean pore diameter mirrored the pattern observed in porosity distribution. Conclusion: Utilizing the continuous skin tissue slice reconstruction technique, this study successfully reconstructed a high-precision three-dimensional tissue structure of the skin. The quantitative analysis of dermal tissue porosity and average pore diameter provides a standardized dataset for the development of biomimetic tissue-engineered skin.

Elasmobranch assemblages from a bathyal environment spanning the Cretaceous-Paleogene boundary in Austria

Abstract Extensive bulk-sampling of the continuous Cretaceous-Paleogene boundary section at Gams (Styria, Austria) allows for the first time the description of the elasmobranch communities inhabiting the bathyal environment of this well-known section. The sampled succession comprises six horizons from the uppermost Maastrichtian (upper part of Nephrolites frequens Zone CC26) and five horizons from the lowermost Danian (Zone NP1), which yielded a total of 1852 elasmobranch teeth. Although the majority of the teeth are not well preserved, this study enabled the description of at least 16 taxa of the orders Hexanchiformes, Squaliformes, Orectolobiformes, Lamniformes and Carcharhiniformes, providing a rare snapshot of elasmobranch diversity of this specific environmental setting. Beside minor diversity fluctuations between the assemblages, the extensive bulk-sampling of this section did not reveal a marked diversity decline related to the end-Cretaceous mass extinction event. However, a noteworthy correlation between the deepening upward trend of the section with the appearance of frilled and goblin sharks points to changes in palaeobathymetry, which is also reflected in the increase of the total proportion of squaliform teeth in the uppermost sampled horizon. Furthermore, teeth of the extinct triakid Palaeogaleus were recovered exclusively from the Danian deeper deposits, expanding the palaeoecological range of the genus down to fairly deep marine environments. In addition, this study provides the first record of the lamniform Cretolamna ex gr. borealis from the Danian of the Tethyan Realm expanding the palaeogeographic distribution of this group.

Bigmouth Buffalo (Ictiobus cyprinellus) migratory behaviour and seasonal home range overlap are functions of geographic space in a fragmented riverscape

In temperate rivers, where environmental conditions vary seasonally, many fishes migrate among summer, spawning, and winter habitats. Dams disrupt these migrations, limiting access to habitat and potentially affecting populations. Bigmouth Buffalo ( Ictiobus cyprinellus) is a species of fish with at-risk populations in central Canada. The impact of dams on the extent of Bigmouth Buffalo migration and the overlap between summer and winter home ranges is unknown. Here, we assessed the migratory history of 80 Bigmouth Buffalo tagged with acoustic transmitters in the Red River (USA and Canada), a large binational waterway regulated by semi-passable dams. We sought to understand when and why Bigmouth Buffalo migrate, and how river use varies seasonally. Following more than 6 years of data collection, we found that the degree and probability of overlap between winter and summer home ranges varied by river section between barriers. Importantly, overlap was lowest in the longest continuous river section where well-defined migratory behaviours were observed. The results of this study reveal previously unknown details about Bigmouth Buffalo migration, demonstrate the consequences of river fragmentation on geographic space use, and highlight the importance of river connectivity to fish migration.