Entire Length Research Articles

Endodontic Dentistry: Analysis of Dentinal Stress and Strain Development during Shaping of Curved Root Canals.

Endodontic shaping causes stress and strain in the root canal dentin. Dentin microcracks have the potential to be later followed by root fractures occurring under the occlusal load. The aim of our research was to theoretically determine the values of such dentinal states of stress and strain during the endodontic shaping of curved root canals using finite element analysis (FEA). To highlight the stress concentrations in dentin, two geometric models were created considering the volume of the curved dental root and the contact between the endodontic file and the root canal walls. The application of forces with different values was simulated both on a uniform curved root canal and on a root canal with an apical third curvature of 25° as they would be applied during the preparation of a root canal. In the case of the first model, which was acted upon with a force of 5 N, the deformations of the root canal appeared along the entire working length, reaching the highest values in the apical third of the root, although there were no geometric changes in the shape of the root canal. Regarding the second root model, with an apical third curvature of 25°, although the applied force was 2 N, the deformations were accompanied by geometric changes in the shape of the root, especially in the upper part of the apical third. At a higher force of 7 N exerted on the endodontic file, the geometric shape changed, and the deformation reached extreme critical values. The resulting tensile stresses appearing in the experimental structure varied similarly to the deformations. Significant stress and strain can develop, especially in the apical third of curved root canals during their shaping, and the risk of cracks is higher for endodontically treated teeth presenting severe curvatures in the apical third of the root.

Abstract 16302: Beyond the Veins: A Critical Right Atrial Termination Site in High Burden Paroxysmal Atrial Fibrillation Identified Using Spatiotemporal Dispersion After Failure of High Quality Pulmonary Vein Isolation

Case Presentation: A 55 year-old female with two-year history of persistent atrial fibrillation (AF) presented for elective catheter ablation. Her smart watch recorded frequent prolonged episodes of AF, and event monitoring confirmed 71% AF burden. Metoprolol improved her symptoms only slightly. At the beginning of the procedure, patient’s rhythm was on sinus (NSR). During the completion of pulmonary vein isolation (PVI), the patient developed typical flutter, which degenerated into AF during ablation. Biatrial dispersion mapping in the right atrium (RA) revealed a single highly dispersed area in the posterior RA. Ablation at this site immediately terminated AF to NSR. The patient was non-inducible and remains free of AF. Discussion: Maintenance of NSR in AF is associated with improved clinical outcomes and quality of life. Catheter ablation has the highest efficacy for minimizing AF burden. PVI has a success rate of 67-89% in treating patients with paroxysmal AF and PVI alone is typically employed. A dispersion area is characterized by local clusters of electrograms which may or may not be fractionated, and display interelectrode time and space dispersion such that activation is spread over the entire AF cycle length. Identification and ablation of dispersion regions in persistent AF has demonstrated a high acute termination rate and improved outcomes in early follow-up, but is difficult to reproduce (Seitz et al. 2017). Here, we present a case of a patient with high burden paroxysmal AF who underwent PVI but remained in AF. Using visual dispersion mapping, we were able to identify a critical RA dispersion area, which rendered patient non-inducible (Figure 1).

Complete mitogenome assembly of Selenicereus monacanthus revealed its molecular features, genome evolution, and phylogenetic implications

BackgroundMitochondria are the powerhouse of the cell and are critical for plant growth and development. Pitaya (Selenicereus or Hylocereus) is the most important economic crop in the family Cactaceae and is grown worldwide, however its mitogenome is unreported.ResultsThis study assembled the complete mitogenome of the red skin and flesh of pitaya (Selenicereus monacanthus). It is a full-length, 2,290,019 bp circular molecule encoding 59 unique genes that only occupy 2.17% of the entire length. In addition, 4,459 pairs of dispersed repeats (≥ 50 bp) were identified, accounting for 84.78% of the total length, and three repeats (394,588, 124,827, and 13,437 bp) mediating genomic recombination were identified by long read mapping and Sanger sequencing. RNA editing events were identified in all 32 protein-coding genes (PCGs), among which four sites (nad1-2, nad4L-2, atp9-copy3-223, and ccmFC-1309) were associated with the initiation or termination of PCGs. Seventy-eight homologous fragments of the chloroplast genome were identified in the mitogenome, the longest having 4,523 bp. In addition, evolutionary analyses suggest that S. monacanthus may have undergone multiple genomic reorganization events during evolution, with the loss of at least nine PCGs (rpl2, rpl10, rps2, rps3, rps10, rps11, rps14, rps19, and sdh3).ConclusionsThis study revealed the genetic basis of the S. monacanthus mitogenome, and provided a scientific basis for further research on phenotypic traits and germplasm resource development.

Development of a multifunctional installation of fine dispersed irrigation

The intensification of the processes of mining and processing of mineral raw materials, characteristic of the modern development of mining production, is associated with significant dust pollution of the atmospheric air. As an economical and mobile means of dust suppression, it is recommended to use the developed impulse fine-dispersed irrigation system "Ustimor". The principle of operation of the installation is based on the pulsed displacement of water from the water-air tank by the combustion products of the fuel-air mixture under high pressure (>5 MPa). Experimental and industrial tests of the installation were carried out at the tailings storage facility of PJSC "Ingulets Mining and Processing Plant". The range of the installation is on average 120-130 m. The area of the irrigated surface in one cycle of operation is from 500 m2 to 750 m2. Fine spraying was observed along the entire length of the jet flight. In one hour of operation, the installation can release from 5 to 30 tons of water into the atmosphere in the form of drizzle. The intensity of watering for one work cycle is on average 0.85 l/m2. The possibility of autonomous operation of the installation and its remote control through the SCADA system has been confirmed. The installation of pulse fine-dispersed irrigation is recommended for use as a means of spraying liquid by the method of fine-dispersed irrigation on open areas of surfaces where dust is intensively swept and suspended. It can be used for dust suppression and humidification at tailings storage facilities, warehouses of bulk materials, landfills, technological highways. The "Ustimor" installation can also be used for fine-dispersed irrigation of plantations, vineyards, gardens, etc. Irrigation of leaf cover and soil surface will lower their temperature by 7 - 10 °C in the sun and by 6 - 6.6 °C in the shade.

Biogeomorphology from space: Analyzing the dynamic interactions between hydromorphology and vegetation along the Naryn River in Kyrgyzstan based on dense satellite time series

The structure and development of river corridors are controlled by an interplay of hydrological, geomorphological and ecological processes over a range of spatial and temporal scales. The majority of existing studies on fluvial biogeomorphology focus either on conceptual development or on investigations on the scales of single geomorphic units or study reaches. With this study, we extend the view on biogeomorphology beyond the reach scale using satellite time series. We take the Naryn River in Kyrgyzstan as an example for demonstrating our approach to biogeomorphological analysis of river corridors. The Naryn is still in a natural state on an entire flow length of more than 600 km with full longitudinal and lateral connectivity. Along the central part of the catchment, the Naryn is a highly dynamic braided river system. This makes this river ideal to study large scale biogeomorphological dynamics. In our study, we follow the well-established concept of biogeomorphological succession. We mapped the different succession stages in the field and used the results to derive spectral-temporal indices characterizing the different biogeomorphological succession stages. Monthly time series of the modified difference water index as well as the normalized difference vegetation index derived from the Landsat archive have been used to compute statistical trends and changepoints by means of a Bayesian time series decomposition algorithm. The results are then evaluated regarding biogeomorphological succession and disturbance events. The results show that dense satellite time series are well suited to derive indicators of biogeomorphological interactions on large spatial scale. The temporally continuous nature of this kind of observations allows an observation of processes and an interpretation for instance against the background of the theory of adaptive cycles and panarchy. In conclusion, the suggested approach has the potential to give new insights in the structure and functioning of entire river corridors or networks.

Simulation of time-varying corrosion rate of rebars and corrosion-induced cracks in reinforced concrete structures subjected to chloride contamination

Corrosion of rebars and consequent corrosion-induced cracks significantly deteriorate durability and serviceability of reinforced concrete (RC) structures. This paper presents a time-dependent numerical model to simulate the entire corrosion process from initiation stage to crack propagation stage and consider the effect of cracks on the development of corrosion current density. Chloride transport model was implemented to determine evolution of corroded area in cross-section of rebars, while two configurations of corroded length along the bar axis was considered: (1) the entire length of rebar was simultaneously corroded and (2) the corroded length evolved gradually from the middle of the bar towards its two ends. Corrosion current density was calculated based on microcell and macrocell electrochemical mechanisms, while a mechanical model was established to simulate corrosion-induced concrete cracking. The results showed that the proposed numerical model was capable of predicting natural corrosion process and consequent crack propagation in RC structures subjected to chloride attack. When cracks developed through the concrete cover, corroded area spread faster, microcell and macrocell current densities increased, and the rust layer became more rounded.

Structure of the native myosin filament in the relaxed cardiac sarcomere

The thick filament is a key component of sarcomeres, the basic units of striated muscle1. Alterations in thick filament proteins are associated with familial hypertrophic cardiomyopathy and other heart and muscle diseases2. Despite the central importance of the thick filament, its molecular organization remains unclear. Here we present the molecular architecture of native cardiac sarcomeres in the relaxed state, determined by cryo-electron tomography. Our reconstruction of the thick filament reveals the three-dimensional organization of myosin, titin and myosin-binding protein C (MyBP-C). The arrangement of myosin molecules is dependent on their position along the filament, suggesting specialized capacities in terms of strain susceptibility and force generation. Three pairs of titin-α and titin-β chains run axially along the filament, intertwining with myosin tails and probably orchestrating the length-dependent activation of the sarcomere. Notably, whereas the three titin-α chains run along the entire length of the thick filament, titin-β chains do not. The structure also demonstrates that MyBP-C bridges thin and thick filaments, with its carboxy-terminal region binding to the myosin tails and directly stabilizing the OFF state of the myosin heads in an unforeseen manner. These results provide a foundation for future research investigating muscle disorders involving sarcomeric components.

Loci of the genotyping panel by sequencing using AgriSeq technology in the Manych Merino breed

Using the genotyping of sheep of the Manych Merino breed on the basis of Illumina BeadChip Ovine 600K, loci suitable for genotyping by sequencing animals of this breed were found. Single nucleotide polymorphisms with a high frequency of occurrence in the range of 0.2850-0.3149 homozygotes of both wild and mutant variants were identified. Heterozygous variants of these substitutions occurred with a frequency of 0.379±0.012. The number of polymorphisms corresponding to the selected criteria was 521. Analysis of the location of the detected SNPs in the sheep genome showed their presence along the entire length of the genotyped DNA region. The largest number of polymorphisms were found on chromosomes 1, 2, 3, 17 and X. The least polymorphisms were detected on chromosomes 18, 21, 24 and 25. The resulting set of substitutions will effectively solve the problems of confirming the authenticity of the origin of sheep of the Manych Merino breed, accurately identify animals in the process of breeding work, and account for inbreeding in the population. The proposed set of SNPs is recommended both for use in genotyping by sequencing of a new generation, and for customization of SNP biochips.

Reynolds phytoplankton functional classification approach helps evaluate the historical ecological status of the large European Southern Bug River (Ukraine)

AbstractThe phytoplankton functional group (FG) classification system sensu Reynolds enables evaluating the ecological status of rivers using the Q(r) compositional index. Here, we apply the Q(r) index to analyze the ecological conditions of the Southern Bug River, at the entire river length, in the early 20th century, testing it first on historic river phytoplankton data. Moreover, we combined the FG approach with the saprobic index and taxonomic richness to assess the ecological status of the river more reliably. The Bray–Curtis Similarity index highlighted the spatial clustering of river sites that corresponded well to the bioregions of the Eastern Lowlands and the Pontian Province. The Q(r) index revealed a higher variation in ecological status among sites than the saprobic index. Therefore, we argue that the FG approach provides a sensitive ecological status indication approach for river phytoplankton, including historical human impacts. The method may improve understanding of reference conditions and assessing the ecological status of Ukrainian rivers, as requested by the European Water Framework Directive.

An investigation of rain-wind induced vibrations on stay cables in a novel range of operating conditions

The large-scale rain-wind induced vibration (RWIV) dynamic test rig at the National Research Council Canada (NRC) was used in the current work to evaluate the vibration characteristics of a 0.218 m diameter smooth stay cable, for two cable inclinations and a wide range of yaw-angle conditions. The structural damping ratio was in the range of 0.05% to 0.11% and the heave frequency was approximately 1.23 Hz for a cable with a moving mass of 217 kg. The presence of RWIV was investigated at an inclination angle of 30° from the horizontal over a yaw-angle range of 25° to 45°and for an inclination angle of 55° over a yaw-angle range of −40° to ＋45°. An upper rivulet was present when vibrations were observed. For positive yaw angles, the upper rivulet was characterized by a thin line of water, approximately 5 to 10 mm wide, running along the entire length of the inclined cable on the windward side and moving along the cable span with a serpentine motion. For negative yaw angles, the upper rivulet was located near top of the cable or on the leeward sector of the cable, was wider than the rivulets observed for positive yaw angles, and was not observed to move in a serpentine motion. RWIVs were observed for each yaw angle that was investigated, including at negative yaw angles, with a maximum amplitude of motion of ±150 mm (∼0.7D). The direction of the rain impingement was an important factor affecting the formation and characteristics of the upper rivulet at the surface of the cable and, for the onset for vibrations. RWIVs were observed for wind speeds between 5 and 12 m/s. The Reynolds number corresponding to the onset of RWIV tended to increase with larger yaw angles in the positive yaw-angle range. At an inclination angle of 30°, the onset of RWIV ranged from 1.2×105 at a yaw of 25° to 1.4×105 at a yaw of 45° while at a cable inclination angle of 55°, the onset of RWIV ranged from 1.08×105 at a yaw of 25° to 1.25×105 at a yaw of 40°. The onset of vibrations for a yaw angle of 0° was at 0.77×105 for a cable inclination of 55°. RWIV was initiated at lower Reynolds numbers at an inclination angle of 55° for negative yaw angles, with vibrations observed at wind speeds as low as 5 m/s (Reynolds number of 0.7×105). The results confirmed the presence of RWIV in well-understood conditions and have effectively expanded the range of conditions over which RWIV has been observed in a wind tunnel. The expanded range over which RWIV was observed includes vibrations at an inclination angle of 55°, vibrations at a yaw angle of 0°, and vibrations at negative yaw angles from −10° to −40°.

Essential Role of BMP4 Signaling in the Avian Ceca in Colorectal Enteric Nervous System Development.

The enteric nervous system (ENS) is principally derived from vagal neural crest cells that migrate caudally along the entire length of the gastrointestinal tract, giving rise to neurons and glial cells in two ganglionated plexuses. Incomplete migration of enteric neural crest-derived cells (ENCDC) leads to Hirschsprung disease, a congenital disorder characterized by the absence of enteric ganglia along variable lengths of the colorectum. Our previous work strongly supported the essential role of the avian ceca, present at the junction of the midgut and hindgut, in hindgut ENS development, since ablation of the cecal buds led to incomplete ENCDC colonization of the hindgut. In situ hybridization shows bone morphogenetic protein-4 (BMP4) is highly expressed in the cecal mesenchyme, leading us to hypothesize that cecal BMP4 is required for hindgut ENS development. To test this, we modulated BMP4 activity using embryonic intestinal organ culture techniques and retroviral infection. We show that overexpression or inhibition of BMP4 in the ceca disrupts hindgut ENS development, with GDNF playing an important regulatory role. Our results suggest that these two important signaling pathways are required for normal ENCDC migration and enteric ganglion formation in the developing hindgut ENS.

Risk Factors for Aortic Dissection

Aortic dissection is a critical condition, which can affect the aorta over its entire length. Characterized by a split between the tunica intima and the tunica media of the aorta, aortic dissection is seen in both sexes, and diagnosis and treatment are decisive for the survival of the patient. Aortic dissection has a wide range of risk factors that contribute to it being one of the most serious of cardiovascular conditions. Diagnosis is based on a thorough knowledge of the condition and its risk factors. This review describes the patient characteristics, drugs, and medical procedures that may contribute to an increased risk of aortic dissection, raising awareness of this life-threatening condition.

Railways of India. Time to update and upgrade

By the second decade of the XXI century, the railway transport of India came up with an important result — the Program announced on April 1, 1992, called Unigauge for the transfer of the railway network to a single gauge of 1676 mm was basically completed. In 2022, the operational length of wide-gauge roads on the Indian railway network was 65,094 km, or 95.7 % of its entire length. This opened up the possibility of creating a modern unified railway transport system and organizing its optimal interaction with other modes of transport.The management of the railway transport of India, represented by the Ministry of Railways, has focused efforts on the modernization of all components of the large railway economy — strengthening track structures, upgrading bridge facilities, introducing modern means of ensuring train traffic and transportation safety, updating rolling stock. The basis for improving the work of railway transport is the electrification of railways, the completion of which is planned in the next decade.All decisions taken to modernize railways are aimed at reducing operating costs, improving efficiency, environmental cleanliness, comfort and speed of passenger travel, reducing the delivery time of goods, as well as improving the safety of transportation by rail.

Similarity and Change Detection of Relief in a Proglacial River Valley (Scott River, SW Svalbard)

This study focuses on contemporary geomorphic changes in the proglacial valley floor of the Scott River catchment (northwest of Wedel Jarlsberg Land, southwestern Spitsbergen). The similarity and variability of landforms along the entire 3.3 km length of the unglaciated valley floor was assessed using precision terrestrial laser scanning (TLS) measurements made in July/August 2010–2013. Digital terrain models (DTMs) were generated from the high-resolution TLS survey data, followed by a geomorphon map, which was then used for a similarity and changes of morphology analysis performed with GeoPAT2 software. The study revealed a large spatial variation of contemporary processes shaping the valley floor and changes in its morphology. Their spatial distribution relates to the geologically determined split of the valley floor into three morphological zones separated by gorges. The upper gorge cuts the terminal moraine rampart, which limits the uppermost section of the valley floor, which is up to 700 m wide and is occupied by the outwash plain. The study showed that this is the area characterised by the greatest dynamics of contemporary geomorphic processes and relief changes. The similarity index value here is characterised by a large spatial variation that in some places reaches values close to 0. In the middle section stretching between the upper gorge (cutting the terminal moraine) and the lower gorge (cutting the elevated marine terraces), a much smaller variability of processes and landforms is observed, and the found changes of the valley floor relief mainly include the area of braided channel activity. Similarity index values in this zone do not fall below 0.65. The lowest section, the mouth of the alluvial fan, on the other hand, is characterised by considerable spatial differentiation. The southern part of the fan is stable, while the northern part is intensively re-shaped and has a similarity index that locally falls below 0.5. The most dynamic changes are found within the active channel system along the entire length of the unglaciated section of the Scott River. The peripheral areas, located in the outer zones of the valley floor, show great stability.

Eukaryotic translation elongation factor 1 alpha (eEF1A) inhibits Siniperca chuatsi rhabdovirus (SCRV) infection through two distinct mechanisms.

Although a virus can regulate many cellular responses to facilitate its replication by interacting with host proteins, the host can also restrict virus infection through these interactions. In the present study, we showed that the host eukaryotic translation elongation factor 1 alpha (eEF1A), an essential protein in the translation machinery, interacted with two proteins of a fish rhabdovirus, Siniperca chuatsi rhabdovirus (SCRV), and inhibited virus infection via two different mechanisms: (i) inhibiting the formation of crucial viral protein complexes required for virus transcription and replication and (ii) promoting the ubiquitin-proteasome degradation of viral protein. We also revealed the functional regions of eEF1A that are involved in the two processes. Such a host protein inhibiting a rhabdovirus infection in two ways is rarely reported. These findings provided new information for the interactions between host and fish rhabdovirus.

A new species of possible archipolypodan millipedefrom the Carboniferous of the Netherlandswith unusually long tergites

Millipedes have a long evolutionary history, with the oldest presumed fossils of Diplopoda de Blainville in Gervais, 1844 being from the Silurian and the first definite fossil record originating from Devonian deposits. The phylogeny of Diplopoda is not fully resolved yet, especially not concerning fossil representatives. At the same time, already in the Palaeozoic millipedes showed quite a morphological and presumably also ecological variety. We describe here a new species of a Carboniferous millipede from the Westphalian A of the Netherlands, Lauravolsella willemeni n. gen., n. sp., a possible representative of Archipolypoda (†Archipolypoda Scudder, 1882). The species is based on a single specimen, preserved with part and counterpart, which both show a three-dimensional preservation. The specimen has unusually long tergites, in normal life position covering most of the following segment. These long tergites might have been beneficial when performing defensive enrolling. In extant millipedes, enrolling is usually facilitated by softer areas between the sternites, allowing for a certain degree of ventral compression. In the new fossil, the sclerotic sternites occupy the entire length of the ventral side of the segment, not allowing for any type of compression. The new fossil therefore demonstrates another solution for the mechanical challenges during enrolment and increases the morphological diversity of Carboniferous millipedes.

Targeted rRNA depletion enables efficient mRNA sequencing in diverse bacterial species and complex co-cultures.

Microbes present one of the most diverse sources of biochemistry in nature, and mRNA sequencing provides a comprehensive view of this biological activity by quantitatively measuring microbial transcriptomes. However, efficient mRNA capture for sequencing presents significant challenges in prokaryotes as mRNAs are not poly-adenylated and typically make up less than 5% of total RNA compared with rRNAs that exceed 80%. Recently developed methods for sequencing bacterial mRNA typically rely on depleting rRNA by tiling large probe sets against rRNAs; however, such approaches are expensive, time-consuming, and challenging to scale to varied bacterial species and complex microbial communities. Therefore, we developed EMBR-seq+, a method that requires fewer than 10 short oligonucleotides per rRNA to achieve up to 99% rRNA depletion in diverse bacterial species. Finally, EMBR-seq+ resulted in a deeper view of the transcriptome, enabling systematic quantification of how microbial interactions result in altering the transcriptional state of bacteria within co-cultures.

Direct Temperature Measurements of Cardiac Stent during MRI Examinations

Nowadays, Magnetic Resonance Imaging (MRI) is considered the gold standard for imaging the brain, spinal cord, musculoskeletal system, head and neck, and complex congenital heart malformations; consequentially, the number of MRI scans in patients with implantable electronic devices has simultaneously increased. During the entire length of the MRI exam, patients are exposed to electromagnetic fields with different characteristics (static, low frequency, radiofrequency fields), which are related to different risks. The scarce available literature about MRI-induced heating on cardiac stents suggests that excessive temperature rise occurs only in unfavorable cases. Ideally, RF safety assessment could be performed during the anamnestic process, but this simulation process’s results are too slow to be performed before patient MRI examination. In this context, we developed a dedicated measurement set-up by focusing our target on the measurement of the heating of a cardiac stent during an MRI examination. Results for the temperature rise trend along the entire stent length during a clinical MRI protocol are shown together with the local Specific Absorption Rate (SAR) values and cumulative equivalent minutes at 43 °C (CEM43°C), in order to ensure the safety of patients with MR-conditional devices, also with a view to not inappropriately preclude their access to MRI scans. The obtained results show that the maximum temperature rise (4.12 °C) is within the limit of 5 °C stated in the stent manual for 15 min of continued scanning with the specific conditions. The maximum temperature rise was in correspondence with the stent tips and calculated SAR confirms the fact that two hotspots are present near the tips of the stent. Finally, the calculated CEM43°C remained well below the proposed threshold for muscle tissue.

Field assessment of elastic full-waveform inversion of combined accelerometer and distributed acoustic sensing data in a vertical seismic profile configuration

Seismic data are a significant facilitator for monitoring in carbon capture and sequestration projects, providing high-resolution images of fluid migration, using, for example, full-waveform inversion (FWI). Distributed acoustic sensing (DAS), a relatively novel technology for wavefield sampling, is well suited for this type of monitoring. Using noninvasive optical fibers, DAS allows for dense spatial sampling along the entire length of the wellbore, without disrupting operations. Permanently installed in the wellbore, typically behind casing, DAS offers highly repeatable and dense sampling of the transmitted wave modes crucial to seismic monitoring of injected carbon dioxide ([Formula: see text]). However, the DAS data consist of measurements of strain along the tangent of the fiber and therefore do not transfer directly to conventional FWI algorithms. Incorporation of DAS data in their native strain (or strain-rate) form in standard FWI algorithms, requires changing the definition of the receiver sampling operator to use geometric information about the fiber to supply tangential strain measurements to the FWI residual. The theoretical developments are applied to invert field vertical seismic profile data acquired with DAS fiber and accelerometers at a [Formula: see text] sequestration site in Newell Country, Alberta. Our method incorporates DAS data and accelerometer data in one objective function and allows us to tune the relative importance we wish to place on each data set. This method also transfers to noncollocated sensors, for example, surface-deployed geophones and borehole fiber. The inverted models contain features expected from the geology of the field site, and data modeled in the inverted models compare favorably with the field data for these sensor types. The models are derived from data acquired prior to [Formula: see text] injection, representing baseline models for future time-lapse studies planned at the field research station.

Piston Error Measurement for Segmented Telescopes Based on a Hybrid Artificial Neural Network.

To address the difficulty and complexity of detecting piston errors for segmented telescopes, this paper proposes a new piston error measurement method based on a hybrid artificial neural network. First, we use the Resnet network to learn the mapping relationship between the focal plane degradation image and signs of the piston error. Then, based on the established theoretical relationship between the modulation transfer function and the piston error, a BP neural network is used to learn the mapping relationship between the MTF and the absolute value of the piston error. After the training of the hybrid network is completed, a wide-range and high-precision detection of the piston error of the sub-mirrors can be achieved using the combined output of the two networks, where only a focal plane image of the point source with broadband illumination is used as the input. The detection range can reach the entire coherent length of the input broadband light, and the detection accuracy can reach 10 nm. The method proposed in this paper has the advantages of high detection accuracy, a wide detection range, low hardware cost, a small network scale, and low training difficulty.