End Of Segment Research Articles

Influenza A virus transcription generates capped cRNAs that activate RIG-I.

During influenza A virus (IAV) infection, host pathogen receptor retinoic acid-inducible gene I (RIG-I) detects the partially complementary, 5'-triphosphorylated ends of the viral genome segments and non-canonical replication products. However, it has also been suggested that innate immune responses may be triggered by viral transcription. In this study, we investigated whether an immunostimulatory RNA is produced during IAV transcription. We show that the IAV RNA polymerase can read though the polyadenylation signal during transcription termination, generating a capped complementary RNA (ccRNA), which contains the 5' cap of an IAV mRNA and the 3' terminus of a cRNA instead of a poly(A) tail. ccRNAs are detectable in vitro and in both ribonucleoprotein reconstitution assays and IAV infections. Mutations that disrupt polyadenylation enhance ccRNA synthesis and increase RIG-I-dependent innate immune activation. Notably, while ccRNA itself is not immunostimulatory, it forms a RIG-I agonist by hybridizing with a complementary negative-sense viral RNA. These findings thus identify a novel non-canonical IAV RNA species and suggest an alternative mechanism for RIG-I activation during IAV infection.

Cell state transitions are decoupled from cell division during early embryo development.

As tissues develop, cells divide and differentiate concurrently. Conflicting evidence shows that cell division is either dispensable or required for formation of cell types. Here, to determine the role of cell division in differentiation, we arrested the cell cycle in zebrafish embryos using two independent approaches and profiled them at single-cell resolution. We show that cell division is dispensable for differentiation of all embryonic tissues from early gastrulation to the end of segmentation. However, arresting cell division does slow down differentiation in some cell types, and it induces global stress responses. While differentiation is robust to blocking cell division, the proportions of cells across cell states are not, but show evidence of partial compensation. This work clarifies our understanding of the role of cell division in development and showcases the utility of combining embryo-wide perturbations with single-cell RNA sequencing to uncover the role of common biological processes across multiple tissues.

Metarhizium fight club: Within-host competitive exclusion and resource partitioning.

Both Metarhizium robertsii ARSEF 2575 (Mr2575) and Metarhizium anisopliae ARSEF 549 (Ma549) infect a range of insects whilst also interacting with plants; however, little is known about the traits that affect the competitive ability of different strains. We examined the interactions between Mr2575 and Ma549 in culture and during co-infection of plants (Arabidopsis thaliana) and insects. Mr2575 outcompetes Ma549 under nutrient-limiting conditions, including root exudates, giving it a priority advantage on Arabidopsis roots. However, during co-infection of Manduca sexta or Drosophila melanogaster, Ma549's higher blastospore production enhanced its competitive ability within the host. In large M. sexta (fifth instar), blastospores facilitate dispersal, suppress host melanization and prevent Mr2575 from spreading from infection sites, reducing conidia production. However, colonization of smaller hosts such as first instar M. sexta and D. melanogaster did not provide Ma549 with a competitive advantage, as conidial production was dependent on retaining control of the cuticle through which conidiating hyphae emerge. Unexpectedly, Ma549 and Mr2575 segregate within hosts, suggesting resource partitioning with Mr2575 predominating in the thoraxes of Drosophila, especially in females, and Ma549 in the abdomen. In fifth instar M. sexta, Mr2575 was most prevalent around spiracles and the front end of segments, despite Ma549 and Mr2575 having similar susceptibility to hypoxia. Dispersing conidia homogeneously into the hemocoel of fifth instar M. sexta eliminated the blastospore production advantage, making Ma549 and Mr2575 equally competitive, with strict partitioning of Mr2575 at the anterior and Ma549 at the posterior ends of segments. As Metarhizium species have multiple roles in natural ecosystems and agroecosystems these discoveries are relevant to understanding their impact on maintaining biodiversity and for exploiting them to enhance food security.

Lytic promoter activity during herpes simplex virus latency is dependent on genome location.

Herpes simplex virus 1 (HSV-1) is a significant pathogen that establishes lifelong latent infections with intermittent episodes of resumed disease. In mouse models of HSV infection, sporadic low-level lytic gene expression has been detected during latency in the absence of reactivation events that lead to production of new viruses. This viral activity during latency has been reported using a sensitive Cre-marking model for several lytic gene promoters placed in one location in the HSV-1 genome. Here, we extend these findings in the same model by examining first, the activity of an ectopic lytic gene promoter in several places in the genome and second, whether any promoters might be active in their natural context. We found that Cre expression was detected during latency from ectopic and native promoters, but only in locations near the ends of the unique long genome segment. This location is significant because it is in close proximity to the region from which latency-associated transcripts (LATs) are derived. These results show that native HSV-1 lytic gene promoters can produce protein products during latency, but that this activity is only detectable when they are located close to the LAT locus.IMPORTANCEHSV is a significant human pathogen and the best studied model of mammalian virus latency. Traditionally, the active (lytic) and inactive (latent) phases of infection were considered to be distinct, but the notion of latency being entirely quiescent is evolving due to the detection of some lytic gene expression during latency. Here, we add to this literature by finding that the activity can be found for native lytic gene promoters as well as for constructs placed ectopically in the HSV genome. However, this activity was only detectable when these promoters were located close by a region known to be transcriptionally active during latency. These data have implications for our understanding of HSV gene regulation during latency and the extent to which transcriptionally active regions are insulated from adjacent parts of the viral genome.

Research on Subsurface Electrical Structure Based on a Dense Geomagnetic Array in Southern Yunnan.

The electrical resistivity of subsurface rocks is one of the important sensitive parameters characterizing the internal physics of the Earth. Currently, research on subsurface electrical structures using geomagnetic sounding methods primarily focuses on two approaches: the first is based on observations from a few geomagnetic stations, which have low spatial resolution and cannot effectively describe the distribution of anomalies; the second is based on mobile geomagnetic observations, which have low temporal resolution and cannot promptly reflect anomalies. To address these issues, this study deployed a dense geomagnetic array for long-term observation in the southern segment of the Xiaojiang Fault Zone in the Yuxi area of southern Yunnan. This setup aims to promptly capture seismic magnetic anomalies, providing more data support and fundamental information for short-term earthquake prediction. Based on the long-term observation data from the dense array, the study of the subsurface electrical structure is carried out. The results indicate that during the observation period, which was seismically quiet, the regional subsurface electrical structure remained stable. A large-scale subsurface low-resistivity body was observed in the region, and the electrical structures at the two ends of the southern segment of the Xiaojiang Fault Zone were found to be completely different.

Protein folding, protein dynamics and the topology of self-motions.

It has long been recognized that segments of the protein main chain are like robotic manipulators and inverse kinematics methods from robotics have been applied to model loops to bridge gaps in protein comparative modelling. The complex internal motion of a redundant manipulator with fixed ends is called a self-motion and its character is determined by the relative position of its ends. Self-motions that are topologically equivalent (homotopic) occupy the same continous region of the configuration space. Topologically inequivalent (non-homotopic) regions are separated by co-regular surfaces and crossing a co-regular surface can result in a sudden dramatic change in the character of the self-motion. It is shown, using a five-residue type I β-turn, that these concepts apply to protein segments and that as the ends of the five-residue segment come closer together, a co-regular surface is crossed, and the structure is locked in to becoming either a type I or type I' turn. It is also shown that the type II turn is topologically equivalent to the type I' turn, not the type I turn. These results have implications for both native-state protein dynamics and protein folding.

Haemodynamic study of left nonthrombotic iliac vein lesions: a preliminary report

Nonthrombotic iliac vein lesions (NIVLs) are significant causes of chronic venous insufficiency (CVI) in the left lower limb and symptom recurrence following left lower limb varicose vein treatment. The goal of this study was to explore the haemodynamic and morphological characteristics of iliac veins in patients with NIVLs. Pressure at the caudal end of the stenotic left common iliac vein (LCIV) segment, local blood flow velocity, and time-averaged wall shear stress in the stenotic segment exhibited positive correlations with the clinical CVI classification (R = 0.92, p < 0.001; R = 0.94, p < 0.001; R = 0.87, p < 0.001), while the relative retention time showed a negative correlation (R = -0.94, p < 0.001). The pressure difference (∆P) between the two ends of the stenotic segment and the velocity difference (∆V) between the stenotic segment and the caudal end were positively correlated with the clinical classification (R = 0.92, p < 0.001; R = 0.9, p < 0.001). The cross-sectional area stenosis rate and length of the stenotic LCIV segment were positively correlated with the clinical classification (R = 0.93, p < 0.001; R = 0.63, p < 0.001). The results suggest that haemodynamic assessment of the iliac vein could effectively portray blood flow disturbances in stenotic segments of the LCIV, potentially reflecting the degree of iliac vein stenosis. Haemodynamic indicators are correlated with the severity of clinical CVI symptoms.

Isolation and identification of a pigeonpox virus strain and study on the integration of reticuloendotheliosis virus sequence.

In order to study the integration of reticuloendotheliosis virus (REV) in pigeonpox virus (PPV), we collected suspected pigeonpox disease material, amplified the 4b core protein gene of PPV, the gp90 gene of REV, and the integrated sequence fragments from the end of the ORF201 segment of PPV to the beginning of the LTR of REV, and sequenced these genes. The results showed that a 4b core protein fragment of 332bp was amplified and identified as pigeonpox virus, which was named SX/TY/LTR 01/2023. Sequence analysis showed that the pigeonpox virus isolate belonged to genotype A2, which was the closest to the domestic CVL strain, with a identity of 99.4%. A band of 1191bp was amplified from the gp90 gene of REV, named SX/TY/PPV-REV01/2023, and sequence analysis indicated that REV belonged to genotype III. The sequence analysis showed that REV belonged to genotype III, and belonged to the same large branch as the domestic isolates JSRD0701 and LNR0801, with 99.3% identity. The integrated sequence fragment was amplified to a band of 637bp, which determined that the REV sequence was integrated in the PPV rather than a mixed infection of the two viruses. This indicates that REV was integrated in this isolation of PPV, suggesting that pigeon farms need to prevent reticuloendotheliosis at the same time when preventing pigeonpox.

A novel screw-type pyrolysis system for selectively producing value-added chemicals from lignocellulosic biomass

AbstractIn this study, a new unique screw-type (auger) reactor system was developed to selectively obtain valuable chemical-enriched liquid pyrolysis products. The new design has heating segments with increased temperature along the reactor tube and three-staged fractional condensing lines following pyrolysis gas ports at the end of each heating segment. To maximize liquid product yield, the effects of some parameters such as feeding rate, screw rate, and temperature profile were studied by the experiments designed with Response Surface Methodology (RSM). By fixing the maximum temperature at the last heating segment of a tubular reactor to 550 °C, the conditions for maximum liquid product yield were determined as feeder driver frequency of 21 Hz (13.6 rpm), auger driver frequency of 36 Hz (24.3 rpm), and ΔT (temperature difference between consecutive heating segments) of 66 °C. Biomass feeding rate and volumetric fullness ratio of the reactor at these conditions were 42 g min−1 and 0.58 (v/v), respectively. Under these conditions, total liquid, solid, and gas product yields were obtained as 57%, 19%, and 24%, respectively. In addition, analyses of the liquid fractions showed that valuable chemicals could be obtained selectively in a large extent by using the new design.

Comprehensive Study on the 143 A.D. West Gangu Earthquake in the West Qinling Area, Northeastern Margin of Tibetan Plateau

The 143 A.D. west Gangu earthquake is documented to have occurred in the West Qinling area, which is located on the northeastern margin of the Tibetan Plateau. Initial limited historical records suggest the earthquake took place along the West Qinling fault (WQLF) in the western region of Gangu County. However, the absence of corresponding geological and geomorphological evidence has posed a considerable challenge in accurately quantifying parameters such as the precise location, magnitude, and seismogenic fault segment in earlier investigations. In this study, a comprehensive examination of multiple residual surface rupture zones within the macroseismic zone of this earthquake enabled the determination of the seismogenic structure, magnitude, and rupture zone scale through diverse methodologies, which include field geological investigations, chronology testing, Unmanned Aerial Vehicle (UAV) aerial surveying, and interpretation of landslides along the fault zone. The results reveal that the seismogenic structure of this seismic event is associated with the Zhangxian fault segment of the WQLF, also marked by a dense distribution of large landslides from Zhangxian to Yuanyangzhen. The epicenter was identified at the eastern end of the Zhangxian fault segment of the WQLF. Furthermore, the magnitude of the 143 A.D. west Gangu earthquake is estimated to be approximately Ms 7–7.3, with the residual surface rupture zone intermittently extending over about 22 km and a maximum horizontal dislocation along the rupture zone of 2.8 ± 0.5 m. This detailed investigation contributes foundational insights for further evaluating the seismic risk across various segments of the WQLF.

Clinical characteristics and literature review of ectopic gastric mucosa in the small intestine

The study aims to summarize the clinical characteristics of patients with ectopic gastric mucosa in the small intestine, comparing clinical presentation differences between domestic and foreign patients through literature review. The clinical characteristics of cases diagnosed with ectopic gastric mucosa in the small intestine at Peking Union Medical College Hospital from January 2000 to January 2024 were retrospectively analyzed. By searching databanks, such as PubMed, EMBASE, the Cochrane Library, Wanfang, VIP, CNKI, and etc (the inclusion period was from the establishment of the database to January 1, 2024). The literature review was conducted on ectopic gastric mucosa in the small intestine. A total of 10 cases were included, all male, age [M (Q1, Q3)] was 27 (13-69) years old. Gastrointestinal bleeding was the first manifestation in most cases, with severe cases leading to hemorrhagic shock. Abdominal CT indicated local intestinal wall thickening and luminal narrowing in 3 cases. Four cases lesions were located at the beginning of the jejunum and 6 lesions were located in the end segment of ileum. All cases underwent local lesion resection, with postoperative pathology confirming ectopic gastric mucosa. Symptoms disappeared postoperatively, with a follow-up period of 0.5-3.0 years. Literature review indicates that the main clinical manifestation of gastric mucosa ectopia in the small intestine in China is gastrointestinal bleeding, while foreign patients are often complicated with intestinal duplication and intussusception, with abdominal pain and vomiting as the primary and main symptoms. The occurrence rate of intestinal obstruction in female patients, both domestically and abroad, is higher than that in male patients. The occurrence rate of ileal lesions with intestinal obstruction and small intestinal duplication is higher than that of duodenal lesions in both domestic and foreign patients. Local small intestine resection is an effective treatment method with generally good prognosis. Ectopic small intestinal mucosa is relatively rare, with symptoms of gastrointestinal bleeding and intestinal obstruction being common presentations, which can serve as one of the differential diagnoses for unexplained gastrointestinal bleeding.

Synthetic genomic nanomedicine with triple-responsiveness for systemic anti-tumor therapy

To overcome the biological barriers in the journey of systemic gene delivery, a multifaceted genomic synthetic nanomedicine was elaborated and strategically equipped with a multiple of intriguing responsiveness. Particularly, core–shell plasmid DNA condensates were created based on polyionic complexation with block copolymer of polyethylene glycol (PEG)-polylysine (PLys), namely, the nanoscaled PLys&pDNA nanoparticle tethered with the biocompatible PEG surroundings. Furthermore, redox-reversible disulfide crosslinking was introduced into PLys&pDNA nanoparticle to accomplish adequate structural stabilities, and thermal-responsive polypropylacrylamide (PNIPAM) was introduced as the secondary intermediate surroundings onto the pre-formulated PLys&pDNA nanoparticle with the aim of preventing the potential enzymatic degradation from the environmental nucleases. Hence, hundreds of times prolonged survival and retention was determined in pertinent to the blood circulation properties. Additionally, the installation of a guide ligand at the distal end of PEG segments was proposed to encourage selective tumor uptake. A linear peptide of GPLGVRG, which is selectively susceptible to digestion by the tumor-enriched matrix metalloproteinase 2 (MMP-2), was used as the linkage between the shell and core. This peptide has been shown to detach the bio-inert PEGylation, resulting in further facilitated cell endocytosis and intracellular trafficking activities. Hence, the precisely defined synthetic nanomedicine, which exhibits desirable characteristics, efficient expression of the therapeutic gene in the affected cells, and contributed to potent therapeutic efficacy in systemic treatment of intractable tumors by encapsulating the anti-angiogenic gene.

VEGF-C and 5-Fluorouracil Improve Bleb Survival in a Rabbit Glaucoma Surgery Trabeculectomy Model.

To evaluate VEGF-C-induced lymphoproliferation in conjunction with 5-fluorouracil (5-FU) antimetabolite treatment in a rabbit glaucoma filtration surgery (GFS) model. Thirty-two rabbits underwent GFS and were assigned to four groups (n = 8 each) defined by subconjunctival drug treatment: (a) VEGF-C combined with 5-FU, (b) 5-FU, (c) VEGF-C, (d) and control. Bleb survival, bleb measurements, and IOP were evaluated over 30days. At the end, histology and anterior segment OCT were performed on some eyes. mRNA was isolated from the remaining eyes for RT-PCR evaluation of vessel-specific markers (lymphatics, podoplanin and LYVE-1; and blood vessels, CD31). Qualitatively and quantitatively, VEGF-C combined with 5-FU resulted in blebs which were posteriorly longer and wider than the other conditions: vs. 5-FU (P = 0.043 for longer, P = 0.046 for wider), vs. VEGF-C (P<0.001, P < 0.001) and vs. control (P<0.001, P<0.001). After 30days, the VEGF-C combined with 5-FU condition resulted in longer bleb survival compared with 5-FU (P = 0.025), VEGF-C (P<0.001), and control (P<0.001). Only the VEGF-C combined with 5-FU condition showed a negative correlation between IOP and time that was statistically significant (r = -0.533; P = 0.034). Anterior segment OCT and histology demonstrated larger blebs for the VEGF-C combined with 5-FU condition. Only conditions including VEGF-C led to increased expression of lymphatic markers (LYVE-1, P<0.001-0.008 and podoplanin, P = 0.002-0.011). Expression of CD31 was not different between the groups (P = 0.978). Adding VEGF-C lymphoproliferation to standard antimetabolite treatment improved rabbit GFS success and may suggest a future strategy to improve human GFSs.

Evaluating manual versus automated benthic foraminiferal δ18O alignment techniques for developing chronostratigraphies in marine sediment records

Abstract. Paleoceanographic interpretations of Plio-Pleistocene climate variability over the past 5 million years rely on the evaluation of event timing of proxy changes in sparse records across multiple ocean basins. In turn, orbital-scale chronostratigraphic controls for these records are often built from stratigraphic alignment of benthic foraminiferal stable oxygen isotope (δ18O) records to a preferred dated target stack or composite. This chronostratigraphic age model approach yields age model uncertainties associated with alignment method, target selection, the assumption that the undated record and target experienced synchronous changes in benthic foraminiferal δ18O values, and the assumption that any possible stratigraphic discontinuities within the undated record have been appropriately identified. However, these age model uncertainties and their impact on paleoceanographic interpretations are seldom reported or discussed. Here, we investigate and discuss these uncertainties for conventional manual and automated tuning techniques based on benthic foraminiferal δ18O records and evaluate their impact on sedimentary age models over the past 3.5 Myr using three sedimentary benthic foraminiferal δ18O records as case studies. In one case study, we present a new benthic foraminiferal δ18O record for International Ocean Discovery Program (IODP) Site U1541 (54°13′ S, 125°25′ W), recently recovered from the South Pacific on IODP Expedition 383. The other two case studies examine published benthic foraminiferal δ18O records of Ocean Drilling Program (ODP) Site 1090 and the ODP Site 980/981 composite. Our analysis suggests average age uncertainties of 3 to 5 kyr associated with manually derived versus automated alignment, 1 to 3 kyr associated with automated probabilistic alignment itself, and 2 to 6 kyr associated with the choice of tuning target. Age uncertainties are higher near stratigraphic segment ends and where local benthic foraminiferal δ18O stratigraphy differs from the tuning target. We conclude with recommendations for community best practices for the development and characterization of age uncertainty of sediment core chronostratigraphies based on benthic foraminiferal δ18O records.

Investigation of the affinity and interaction of fibrinogen with trehalose as a protein stabilizer

Trehalose, a remarkable substance, holds great importance in biomedicine for its anti-inflammatory properties and its capacity to hinder scar formation at wounds. This study aims to explore how trehalose interacts with fibrinogen, a crucial protein in wound healing, paying particular attention to their structural characteristics. An array of analytical methods, such as steady-state fluorescence, UV–Vis analysis, circular dichroism (CD), Zeta potential measurements, Dynamic light scattering (DLS), and Fourier-transform infrared spectroscopy (FT-IR), are employed to examine the influence of trehalose on fibrinogen. The findings demonstrate that trehalose induces structural alterations on the surface of fibrinogen, resulting in its compaction. Moreover, computational modeling approaches like docking and molecular dynamics simulations are utilized to enhance the understanding of the interactions between trehalose and fibrinogen. The findings indicate the establishment of a stable complex between the two entities, accompanied by slight modifications in the protein's structure due to their interaction. The main forces facilitating the bonding of trehalose (the ligand) and the protein are hydrogen bonds and van der Waals forces, resulting in an entropy-driven spontaneous bonding process. FT-IR data reveals the emergence of fresh bonds between fibrinogen and trehalose post their interaction, whereas Zeta potential investigations suggest that the engagement with trehalose enhances the stability of the protein structure.Tests assessing cytotoxicity on a typical fibroblast cell line demonstrated that the fibrinogen-trehalose compound displays lower toxicity levels compared to trehalose alone. This suggests a milder impact on cells from the compound. Moreover, molecular docking analysis supports these experimental results, indicating that trehalose molecules primarily bind to the C-terminal end of the coiled-coil segment and the globular area of the Bβ chain within the Dβ fragment. These outcomes highlight the promise of trehalose as a valuable material for wound dressing purposes.

Haemothorax after primary percutaneous coronary intervention for aborted cardiac arrest with cardiopulmonary resuscitation

Cardiopulmonary resuscitation (CPR) is an irreplaceable option in patients with sudden cardiac arrest. However, lifesaving CPR can also put the patients and treating physicians in a predicament with certain rare and life-threatening complications due to chest wall injuries. Hemothorax is one of such complications which must be diagnosed and treated as early as possible, more importantly in patients with acute coronary syndrome (ACS) as a cause of cardiac arrest, wherein antithrombotic drugs are on board. Possible sources of bleeding in hemothorax can be injury to the internal mammary artery (IMA), intercostal arteries, or rarely azygos vein. Careful evaluation for the source of the bleeder is necessary as often bleeders may be missed out in early phase of evaluation due to associated hemodynamic factors such as low mean arterial pressure, raised intrathoracic pressures, and vasospasm. Here, we report a case of ACS with sudden cardiac arrest revived by CPR and primary percutaneous coronary intervention who eventually developed hemodynamically significant hemothorax due to the right IMA injury as detected by catheter-mediated angiography, which was subsequently sealed by vascular microcoils at either ends of the perforated segment.

Composition, Optical Resonances, and Doping of InP/InGaP Nanowires for Tandem Solar Cells: a Micro-Raman Analysis.

We present a micro-Raman study of InP/InGaP tandem junction photovoltaic nanowires. These nanowires render possible InGaP compositions that cannot be made in thin films due to strain. The micro-Raman spectra acquired along the nanowires reveal the existence of compositional changes in the InGaP alloy associated with the doping sequence. The heavily Zn-doped InxGa1-xP (x is the In molar fraction) side of the tunnel diode is Ga rich, x = 0.25, with respect to the n-type and intrinsic segments of the top cell, which are close to the nominal composition of the NWs (x = 0.35). The p-type end segment is still Ga-rich. Electromagnetic resonances are observed in the tunnel diode. The Raman signal arising from the InGaP side of the tunnel diode is significantly enhanced. This enhancement permits the observation of a Raman mode that can be associated with an LO phonon plasmon coupled mode (LOPCM). This mode has not been previously reported in the literature of InGaP, and it permits the Raman characterization of the tunnel diode. The analysis of this mode and its relation to the LO phonon modes of the alloy, InP-like and GaP-like, allows to establish an apparent one-mode behavior for the phonon plasmon coupling. It indicates that hole plasma couples to the GaP-like LO mode. The LOPCMs are modeled using the Lindhard Mermin formalism for the dielectric function.

An Adapted NURBS Interpolator with a Switched Optimized Method of Feed-Rate Scheduling

With the increasing demand for processing precision in the manufacturing industry, feed-rate scheduling is a crucial component in achieving the processing quality of complex surfaces. A smooth feed-rate profile not only guarantees machining quality but also improves machining efficiency. Although the typical offline feed-rate scheduling method possesses good processing efficiency, it may not provide an optimal solution due to the NP-hard problem caused by the feed-rate scheduling of continuous curve segments, which easily results in excess kinetic limitations and feed-rate fluctuations in a real-time interpolation. Instead, the FIR (Finite Impulse Response) method is widely used to realize interpolation in real-time processing. However, the FIR method will filter out a large number of high-frequency signals, leading to a low-processing efficiency. Further, greater acceleration or deceleration is required to ensure the interpolation passes through the segment end at a predefined feed rate and the deceleration in the feed rate profile appears earlier, which allows the interpolation to easily exceed the kinetic limitation. At present, a simple offline or online method cannot realize the global optimization of the feed-rate profile and guarantee the machining efficiency. Moreover, the current feed-rate scheduling that considers both offline and online methods does not consider the situation that the call of offline data and online prediction data will lead to a decrease in the real-time performance of the CNC system. Further, real-time feed-rate scheduling data tend to dominate the whole interpolation process, thus reducing the effect of the offline feed-rate scheduling data. Hence, based on the tool path with C3 continuity (Cubic Continuously Differentiable), this paper first presents a basic interpolation unit relevant to the S-type interpolation feed-rate profile. Then, an offline local smooth strategy is proposed to smooth the feed-rate profile and reduce the exceeding of kinetic limitations and feed-rate fluctuations caused by frequent acceleration and deceleration. Further, a global online smoothing strategy based on the data generated by offline pre-interpolation is presented. What is more, FIR login and logout conditions are proposed to further smooth the feed-rate profile and improve the real-time performance and machining efficiency. The case study validates that the proposed method performs better in kinetic results compared with the typical offline and FIR methods in both the simulation experiment and actual machining experiments. Especially, in actual processing experiments, the proposed method obtains a 28% reduction in contour errors. Further, the proposed method compared with the FIR method obtains a 15% increase in machining efficiency but only a 4% decrease compared with the typical offline method.

Analysis of the clinical characteristics of V4 segment steal blood in the vertebral artery

Objective: To explore the clinical characteristics of unilateral vertebral artery V4 segment occlusive lesions (severe stenosis or occlusion), where the contralateral vertebral artery can be compensated through blood flow and reverse supply to the posterior inferior cerebellarartery (PICA). Methods: This study is a retrospective case series of 66 patients with V4 segment occlusive lesions of unilateral vertebral artery diagnosed and treated from June 2020 to October 2022. Patient data were retrospectively collected, and their hemodynamic characteristics and imaging data were analyzed. Results: Of the 66 cases, 11 patients (16.7%) with V4 segment occlusive disease showed the blood flow of the vertebral artery on the opposite side of the lesion on the digital subtraction angiography (DSA), which can be reverse stolen to the posterior inferior cerebellar artery of the diseased side through the confluence point of the vertebrobasilar artery through the distal end of the ipsilateral vertebral artery V4. Owing to the lack of literature on this pathway and based on the characteristics of previous definitions of subclavian artery steal and carotid artery steal, we referred to this pathway as the vertebral artery V4 segment steal. In 6 patients (9.1%), transcranial Doppler ultrasound (TCD) and transcranial color Doppler ultrasound (TCCD) showed that the blood flow signal was not detected at the proximal end of the V4 segment of the affected side, rather the blood flow direction was reversed at the distal end of the V4 segment, resulting in compensatory acceleration of the blood flow velocity of the V4 segment of the contralateral vertebral artery. Conclusion: "V4 segment steal of vertebral artery" is a very rare route of vertebral artery steal. When V4 segment of the vertebral artery is occluded, clinicians should pay attention to observe the blood supply of PICA and whether there is such a steal route, to better evaluate the blood flow compensation and prognosis of patients.

Flanked Block-Interchange Distance on Strings.

Rearrangement sorting problems impact profoundly in measuring genome similarities and tracing historic scenarios of species. However, recent studies on genome rearrangement mechanisms disclosed a statistically significant evidence, repeats are situated at the ends of rearrangement relevant segments and stay unchanged before and after rearrangements.To reflect the principle behind this evidence, we propose flanked block-interchange, an operation on strings that exchanges two substrings flanked by identical left and right symbols in a string. The flanked block-interchange distance problem is formulated as finding a shortest sequence of flanked block-interchanges to transform a string into the other. We propose a sufficient and necessary condition for deciding whether two strings can be transformed into each other by flanked block-interchanges. This condition is linear time verifiable. Under this condition for two strings, we present a [Formula: see text]-approximation algorithm for the flanked block-interchange distance problem where each symbol occurs at most k times in a string and a polynomial algorithm for this problem where each symbol occurs at most twice in a string. We show that the problem of flanked block-interchange distance is NP-hard at last.