Single Pair Research Articles

Comparison of Focal Hippocampal T2‐Weighted MRI and Whole‐Brain T1‐Weighted MRI for Detection of Longitudinal Atrophy Using Deep Learning‐Based and Conventional Approaches

AbstractBackgroundLongitudinal measurement of medial temporal lobe (MTL) atrophy is shown to be effective in measuring Alzheimer’s disease (AD) progression and has been extensively studied on T1‐weighted MRI. However, there has been little work analyzing atrophy on high‐resolution T2‐weighted MRI of the hippocampal region, and it is unknown which MRI modality would yield a more effective biomarker of disease progression. We compare atrophy measurements derived from T1 and T2‐weighted MRI using a deep learning framework DeepAtrophy and a deformation‐based morphometry method ALOHA.MethodT2‐weighted MRI of 481 participants from ADNI2/3 are included in the study. DeepAtrophy was trained on 74 participants and evaluated on 407. During training, DeepAtrophy explicitly infers temporal information, such as the scan temporal order for a single scan pair and which image pair has a longer scan time interval for multiple scan pairs. During inference, DeepAtrophy predicts a “total progression score” for each scan pair. This score is expected to be higher (more progression) in individuals with more advanced AD. A similar experiment was conducted using T1‐weighted MRI from 481 ADNI2/GO participants (partially overlapping with T2‐weighted experiment). ALOHA pipelines tailored for T1‐weighted and hippocampal T2‐weighted MRI were evaluated on the same subjects and scan pairs as DeepAtrophy.ResultFor both T1 and T2‐weighted MRI, DeepAtrophy is more accurate, compared with ALOHA, in inferring the temporal order of a pair of longitudinal scans. In hypothetical one‐year and two‐years clinical trials scenarios simulated using ADNI data, DeepAtrophy has an improvement over ALOHA in detecting differences in progression between disease groups in both imaging modalities. The strongest effect for differentiating between Amyloid‐positive and Amyloid‐negative cognitively unimpaired group was obtained using DeepAtrophy progression measures on T2‐weighted MRI.ConclusionThis study supports the potential of high‐resolution focal T2‐weighted MRI of the hippocampus as a longitudinal biomarker of early AD progression suitable for future clinical trials.

A multichannel closed bipolar platform to visual electrochemiluminescence sensing of caffeic acid as a model: Potential for multiplex detection

In this study, a fully-featured electrochemiluminescence (ECL) sensing platform based on a multichannel closed bipolar system (closed-BP, C-BP) for the determination of caffeic acid (CA) was successfully developed. The system comprises three individual reservoirs connected to each other by two pairs of gold rods as bipolar electrodes. Moreover, a single pair of gold rods functions as the driving electrodes. Due to configuration consisting of three channels and double-bipolar electrodes, the detection of CA was accomplished in two oxidation and reduction pathways within a single device. Firstly, through close observation of the reactions occurring within the device and utilizing a universal pH indicator and bipolar electrodes, a precise mechanism for the current bipolar systems was initially proposed. Then, the concentration of CA was monitored in the reporting chamber through the following ECL intensities resulting from luminol oxidation and H2O2. The monitoring process was performed using both a photomultiplier tube (PMT) and a digital camera. In the process of analyte oxidation, the PMT and visual (camera)-based detection exhibited a linear response from 5 μmol L−1 to 700 μmol L−1 (limit of detection (LOD) 1.2 μmol L−1) and 50 μmol L−1 to 600 μmol L−1 (LOD 14.8 μmol L−1), respectively. In the analyte reduction pathway, the respective values were 30 μmol L−1 to 450 μmol L−1 (LOD 8.6 μmol L−1) and 55 μmol L−1 to 400 μmol L−1 (LOD 21.2 μmol L−1), for the PMT and visual-based detection, respectively. Our experiments have demonstrated the practical application of the sensor array for efficient and high-performance analysis. This innovative design holds significant potential for diverse fields and paves the way for the development of a user-friendly device.

Choosing only the best voice imitators: Top-K many-to-many voice conversion with StarGAN

Voice conversion systems have become increasingly important as the use of voice technology grows. Deep learning techniques, specifically generative adversarial networks (GANs), have enabled significant progress in the creation of synthetic media, including the field of speech synthesis. One of the most recent examples, StarGAN-VC, uses a single pair of generator and discriminator to convert voices between multiple speakers. However, the training stability of GANs can be an issue. The Top-K methodology, which trains the generator using only the best K generated samples that “fool” the discriminator, has been applied to image tasks and simple GAN architectures. In this work, we demonstrate that the Top-K methodology can improve the quality and stability of converted voices in a state-of-the-art voice conversion system like StarGAN-VC. We also explore the optimal time to implement the Top-K methodology and how to reduce the value of K during training. Through both quantitative and qualitative studies, it was found that the Top-K methodology leads to quicker convergence and better conversion quality compared to regular or vanilla training. In addition, human listeners perceived the samples generated using Top-K as more natural and were more likely to believe that they were produced by a human speaker. The results of this study demonstrate that the Top-K methodology can effectively improve the performance of deep learning-based voice conversion systems.

'Distributed' vision and the architecture of animal visual systems.

More than a century of research, of which JEB has published a substantial selection, has highlighted the rich diversity of animal eyes. From these studies have emerged numerous examples of visual systems that depart from our own familiar blueprint, a single pair of lateral cephalic eyes. It is now clear that such departures are common, widespread and highly diverse, reflecting a variety of different eye types, visual abilities and architectures. Many of these examples have been described as 'distributed' visual systems, but this includes several fundamentally different systems. Here, I re-examine this term, suggest a new framework within which to evaluate visual system distribution in both spatial and functional senses, and propose a roadmap for future work. The various architectures covered by this term reflect three broad strategies that offer different opportunities and require different approaches for study: the duplication of functionally identical eyes, the expression of multiple, functionally distinct eye types in parallel and the use of dispersed photoreceptors to mediate visual behaviour without eyes. Within this context, I explore some of the possible implications of visual system architecture for how visual information is collected and integrated, which has remained conceptually challenging in systems with a large degree of spatial and/or functional distribution. I highlight two areas that should be prioritised in future investigations: the whole-organism approach to behaviour and signal integration, and the evolution of visual system architecture across Metazoa. Recent advances have been made in both areas, through well-designed ethological experiments and the deployment of molecular tools.

Efficacy and Safety of Antithrombin Supplementation in Neonates and Infants on a Continuous Heparin Infusion

Introduction: Antithrombin (AT) is an inhibitor of several coagulation proteins, including FIIa and FXa. Heparins accelerate/potentiate the interaction between AT and these factors through a conformational change in AT. Plasma AT concentrations are low in neonates, lower in sick premature neonates, and reach adult levels by 6 to 12 months of age. The developmental differences in plasma AT levels are an important consideration when treating an infant with heparin, as the activity of heparin depends on the presence of AT as a cofactor. As a result, AT supplementation is often considered in this cohort, particularly in the setting of heparin resistance. Objective: The objective of this study was to describe the use of AT supplementation at Boston Children's Hospital (BCH), a quaternary care, free-standing children's hospital, and investigate the safety and efficacy of AT supplementation in infants on a continuous heparin infusion. Methods: This study was approved by the Institutional Review Board at BCH. Data were abstracted for infants who received AT supplementation while on a therapeutic heparin infusion in the neonatal, cardiac, and medical intensive care units between January 2016 and October 2022. Infants on extracorporeal membrane oxygenation and continuous renal replacement therapy were excluded. The primary outcome was attainment of therapeutic anticoagulation within 48 hours after an AT course, defined as at least one occurrence of a partial thromboplastin time (PTT) level between 60 and 85 seconds and/or anti-factor Xa (anti-FXa) activity between 0.35 and 0.7 units/mL. Clinically relevant bleeding was defined as moderate/clinically relevant non-major bleeding or severe/major bleeding, as determined by either the Neonatal Bleeding Assessment Tool for infants with post-menstrual age (PMA) < 44 weeks or the International Society on Thrombosis and Haemostasis criteria for infants with PMA > 44 weeks, respectively. Data were summarized using descriptive statistics. Results: Over the 7-year period, 50 infants receiving 61 courses of AT supplementation were included. 12 patients received multiple AT doses within a course, resulting in the administration of 75 total AT doses. The median gestational age was 38 weeks (range 28-41 weeks), with a mean birth weight of 3.1 kg (range 0.8-4.5 kg). Median postnatal age at the time of the first AT dose was 19 days (range 3-341 days). The majority of heparin courses were indicated for thrombosis (49%) and post-operative cardiac surgery (40%). Median baseline AT activity was 37% (range 18-61%). The primary outcome was achieved in 90% AT courses. Of these, 73% were therapeutic only by PTT levels, 9% only by anti-FXa activity, and 18% by both. The benefit of AT administration was not sustained, as only 39% PTT levels and anti-FXa activity measured 48 hours after the AT course remained therapeutic. 41 infants had an AT level measured within 6 hours after the dose, and 61% (25/41) achieved a level between 80 and 120% of the calculated target. AT levels decreased over 48 hours, with an estimated half-life of 49 hours. 21% of AT courses had an increase in bleeding severity, with the majority being minor bleeds. Clinically relevant bleeding occurred after AT administration in only 8% (4/50) subjects. The relationship between simultaneously measured PTT levels and anti-FXa activity was investigated in a secondary analysis. Of the 250 paired levels, only one pair was therapeutic for both values ( Figure 1). Other than the single pair, in all other samples with a therapeutic anti-FXa, the simultaneously measured PTT was supratherapeutic. Three of the four patients with clinically relevant bleeding had at least one paired PTT level and anti-FXa activity available on the day of bleeding. Out of the seven paired samples, 86% of moderate bleeding occurred when the PTT level was supratherapeutic and the anti-FXa activity was subtherapeutic. Discussion: AT supplementation in infants may briefly increase the therapeutic efficacy of heparin, dependent on the monitoring parameter used, as PTT levels and anti-FXa activity poorly correlate. Additionally, permitting the PTT to increase over a certain threshold may increase the risk of bleeding. Further studies are needed to provide recommendations on heparin infusion titrations, AT dosing, and the monitoring of PTT levels and/or anti-FXa activity in the neonatal/infant populations on a continuous heparin infusion.

The Association of SEPTIN6 Mutations with Pediatric Myelodysplasia

Septin family proteins belong to the RAS-like GTPase superclass and are considered as a structural element of the cytoskeleton. They are evolutionarily conserved and are important in cytokinesis, polarity, cell cycle, vesicle trafficking, and exocytosis. They are implicated in T and B cell lymphomas; and acute myeloid leukemias, where they frequently act as fusion partners with the Mixed-Lineage Leukemia (MLL) gene. Previously, we described two non-syndromic patients with severe neutropenia which progressed to myelodysplastic syndrome (MDS) (Renella et al. AJH, 2022, Mohamad et al. ASH, 2022). Next-generation sequencing revealed both patients (P1 and P2) to have novel X-linked germline mutations in codon 428 of the SEPTIN6 gene (P1: SEPTIN6 c.1282T>C; P2: SEPTIN6 c.1282T>A). One of these patients (P1) had an additional somatic stop-gain mutation (P1: SEPTIN6 c.43C>T) of unclear function. Both patient germline mutations were predicted to add 9 amino acids to the C-terminal end creating a novel mutated SEPTIN6 protein. Since SEPTIN6 is located on the X-chromosome and expression of these mutated proteins occurred in males, no wild-type protein was present in the patient cells. To further explore the biological relevance of these mutations, single base-pair gene editing was used to introduce the (P1: T>C) mutation into normal male donor CD34+ cells. Morphological studies demonstrated that SEPTIN6 edited cells had enlarged, multi-nucleated and dysplastic nuclei; and reduced clonogenic activity. To further assess the effect of the T>C mutation on hematopoietic stem cell (HSC) function, the SEPTIN6 edited cells were transplanted into immunocompromised NSGW mice. Analysis of peripheral blood demonstrated reduced chimerism in edited recipients (4.27% +/-3.4%) compared to controls (20.56% +/-6.2%, mean+/- SD, p= 0.0008) indicating a functional HSC defect upon mutation acquisition. Bulk mRNA sequencing demonstrated changes in ribosome, DNA replication, homologous recombination and mismatch repair pathways which imply DNA damage and cell cycle defects (Figure 1). To examine the potential dominant negative vs haploinsufficiency role of these mutations, we introduced the mutated SEPTIN6 (P1: SEPTIN6 c.1282T>C) cDNA into wild type human male CD34+ cells. Morphological studies demonstrated enlarged cells with multi-nucleated and dysplastic nuclei. Moreover, clonogenic assays demonstrated that cells containing both the mutated and wild type protein had reduced number of colonies (17.7+/- 5.5) compared to controls (127+/- 13.7, mean+/- SD, p <0.0001). This indicates that the mutated SEPTIN6 protein has a dominant negative effect over the wild type protein. We hypothesized that the somatic stop-gain mutation in the patient (P1) genome may mitigate the deleterious effects of the primary germline SEPTIN6 c.1282T>C mutation. To test this hypothesis, and determine the effect of each individual mutation, we created lentivirus vectors which contained a shmiR against the native SEPTIN6 mRNA and also contained (a) the germline P1: SEPTIN6 c.1282T>C mutation (M2 mutation) alone, or (b) the germline M2 mutation and the somatic stop-gain mutation (P1: M1+M2 mutation) in tandem, or (c) germline P2: SEPTIN6 c.1282T>A (M3 mutation). The wild type SEPTIN6 gene was reintroduced as a control. Clonogenic assays demonstrated that SEPTIN6 knockdown in human CD34+ cells caused no significant change in progenitor activity (Table 1). Furthermore, introduction of the M2 or the M3 germline mutants in SEPTIN6 knocked down cells caused a reduction in the total number of colonies, especially the number of GM colonies with no change in the number of BFU-E colonies (Table 1). This data validates our previous experiments performed with single base pair gene editing in human CD34+ cells. Interestingly, introduction of the stop-gain M1 mutation along with the M2 mutation (M1+M2) reversed the reduced clonogenic activity seen with expression of the M2 mutation (Table 1). This indicates that the M1 mutation by introducing an early stop codon creates a SEPTIN6 knockdown effect and rescues hematopoietic function from the deleterious M2 mutation. Overall, our data demonstrates the acquisition of de novo gain of function mutations in the SEPTIN6 gene in myelopoiesis and suggests deleterious effects on engrafting hematopoietic stem cells. These mutations are associated with the development of MDS in two pediatric patients.

Analysis of the Frequency of Mutations at Diagnostic Oligonucleotide Sites and Their Impact on the Efficiency of PCR for HIV-1.

The development of effective diagnostic kits for HIV-1 remains a pressing concern. We designed diagnostic oligonucleotides for HIV-1 real-time PCR to target the most conserved region of the HIV-1 genome and assessed the mutation frequency at annealing sites. Two databases of nucleotide sequences, Los Alamos and NCBI, were analyzed, revealing that more than 99% of the sequences either lack mutations or contain 1-2 mutations at the binding site of the forward and reverse primers. Additionally, 98.5% of the sequences either lack mutations or contain 1-2 mutations at the binding site of the TaqMan probe. To evaluate the efficiency of primers and the probe in real-time PCR in the case of mutations at their binding sites, we constructed several plasmids containing the most common mutations and, in a model experiment, showed how different mutations affect the efficiency of PCR. Our analysis demonstrated that about 98.5% of HIV-1 strains can be efficiently detected using a single pair of selected primers. For the remaining 1.5% of strains, a more careful selection of the second target is needed.

Phase-field dislocation dynamics simulations of temperature-dependent glide mechanisms in niobium

In this work, we present a three-dimensional ab-initio informed phase-field-dislocation dynamics model combined with Langevin dynamics to investigate glide mechanisms of edge and screw dislocations at finite temperatures in Nb. Over a temperature range of 150 K to 600 K, calculations reveal that the screw dislocation changes its mode of glide at two distinct temperatures. At 200–220 K, the glide mechanism changes from single kink pair motion to multiple kink pair motion. The kink pair enthalpies quantitatively agree with those extracted from experimental tests on Nb single crystals. Between 300 K and 350 K the glide mode transitions to overlapping kink pairs and glide is smooth (non-jerky). The screw to edge mobility ratio is seen to peak at 350 K and plateau thereafter. These two temperatures coincide with temperatures at which yield strengths in Nb are observed to become thermally insensitive and athermal, respectively.

Spin-Stabilization by Coulomb Blockade in a Vanadium Dimer in WSe2.

Charged dopants in 2D transition metal dichalcogenides (TMDs) have been associated with the formation of hydrogenic bound states, defect-bound trions, and gate-controlled magnetism. Charge-transfer at the TMD-substrate interface and the proximity to other charged defects can be used to regulate the occupation of the dopant's energy levels. In this study, we examine vanadium-doped WSe2 monolayers on quasi-freestanding epitaxial graphene, by high-resolution scanning probe microscopy and ab initio calculations. Vanadium atoms substitute W atoms and adopt a negative charge state through charge donation from the graphene substrate. VW-1 dopants exhibit a series of occupied p-type defect states, accompanied by an intriguing electronic fine-structure that we attribute to hydrogenic states bound to the charged impurity. We systematically studied the hybridization in V dimers with different separations. For large dimer separations, the 2e- charge state prevails, and the magnetic moment is quenched. However, the Coulomb blockade in the nearest-neighbor dimer configuration stabilizes a 1e- charge state. The nearest-neighbor V-dimer exhibits an open-shell character for the frontier defect orbital, giving rise to a paramagnetic ground state. Our findings provide microscopic insights into the charge stabilization and many-body effects of single dopants and dopant pairs in a TMD host material.

PATH-66. SEQ-ING THE SINES OF CENTRAL NERVOUS SYSTEM TUMORS IN CEREBROSPINAL FLUID DNA

Abstract It is often challenging to distinguish cancerous from non-cancerous lesions in the brain using conventional diagnostic approaches. We here introduce an analytic technique called Real-CSF to detect cancers of the central nervous system from evaluation of DNA in the cerebrospinal fluid (CSF). Short interspersed nuclear elements (SINEs) from throughout the genome are PCR-amplified with a single primer pair and the PCR products are evaluated by next generation sequencing. Real-CSF assesses genome wide copy number alterations in each of 39 chromosome arms as well as focal amplifications of selected oncogenes. Real-CSF was applied to 280 CSF samples and correctly identified 67% of 184 cancers and 96% of 96 non-cancerous brain lesions. CSF analysis was considerably more sensitive than standard of care cytology and plasma cell-free DNA analysis in the same patients. Real-CSF therefore has the capacity to be used in combination with other clinical, radiologic, and laboratory-based data to inform the diagnosis and management of patients with suspected cancers of the brain.

Plane vortex pairs, colorful structures and low-lying Dirac modes

In this paper, we investigate the influence of topological charges on nonstable zero and near-zero modes of the single uni-color plane vortex pairs. We combine the uni-color plane vortices with the spherical vortex and also construct the plane vortex pairs with two colorful vortices. The stability of zero and near-zero modes is analyzed where various boundary conditions for the fermions are checked. In addition, plane vortex pairs may show the role of the topological charges for changing the chirality of fermions. The results clearly indicate characteristic properties for spontaneous chiral symmetry breaking.

Single Candidate: A Setback to Indonesian Democracy?

The increase in regional head candidates was held in 2015. There were 4 single candidates. In 2017, there were 9 single candidates; in 2018, there were 16 single candidate pairs; for the 2020 regional elections, there was an increase to 25. The phenomenon of single candidates in the Pilkada and the increasing trend of each provincial head election is increasingly attractive to be studied more deeply. This research uses a qualitative approach to analysis by emphasizing process and meaning. Various literature studies related to research on implementing single candidates in simultaneous regional elections from 2015, 2017, 2018, and 2020. Some of the factors of a single candidate for the regional head are the failure of political parties in the cadre process, the high cost of political dowries, the legitimacy of the law, and the difficulty of the requirements for independent candidates to run for regional head elections. The phenomenon of a single candidate in the democratic system in Indonesia certainly attracts the attention of academics, politicians, and the public to study and follow the development process of the local democratic system. The presence of independent candidates will provide an alternative solution to regions in regional head elections that do not have competitors offered by political parties.

High-resolution seismic velocity structure using induced inter-event interferometry at the geothermal sites, Geysers, Eastern California

The possibility of retrieving Rayleigh wave empirical Green's functions (EGFs) using virtual seismometers provides an opportunity to calculate high-resolution velocity models without a set of dense stations and/or expensive seismic imaging/monitoring. The high-resolution tomographic map can give an overview of the fracturing within the saturated rock. Theoretically, the cross-correlations of earthquakes contain significant information about the EGFs between event-pairs. In this work, we developed an application of virtual seismometers on a very small scale in superficial layers where anthropogenic seismicity occurred. To test this method's capabilities, we applied it to investigate the NW-part of The Geysers (TG) geothermal field. We used 1276 micro-earthquakes, occurred in a cuboid with the horizontal side of ∼1 × ∼2 km and the vertical edge at a depth from 0.9 to 2.2 km, to obtain the high-resolution (100 × 100 m) velocity structure. A group of strict criteria was imposed separately for single event waveform and event pairs to stabilize the tomographic results. After retrieving the inter-event EGF signal and calculating the Rayleigh wave group velocity dispersion curves, we obtained the group velocity maps for each horizontal layer. The tomographic maps as a function of depth indicated a low-velocity anomaly related to existing inactive faults, topography variation of the top of the steam zone, and low-velocity anomalies possibly stimulated by fluid injection. The topography of the top of the steam varies from ∼1.0 km to 1.3 km of maps, and also anomalies connected with fluid migration appear at the depth of injection wells (1.5–1.9 km).

Analysis and design of the optimal radius gap of the piston pair

The axial piston pump plays a crucial role as a power component in the hydraulic system. As one of the important friction pairs, the piston pair has a significant influence on the mechanical and volumetric efficiency of the axial piston pump, where the gap of the piston pair has a considerable effect on the lubrication and overall efficiency of the piston. However, there are a few studies on the gap of the piston pair and there is a lack of relevant theoretical support for the design of the gap of the piston pair, especially when the piston has spin motion. To tackle this problem, we propose a CORG (critical and optimal radius gap) design method for the gap of the piston pair based on the critical radius gap and the optimal radius gap. Specifically, we first provide a theoretical proof for the existence of the critical radius gap. Then, considering that the piston has spin motion, we analyze the power loss of the piston pair and define the leakage power loss and viscous dissipation power loss according to the physical meaning. Meanwhile, the minimum value of the total power loss of a single piston pair is taken as the optimization metric of the piston pair, and we further propose the optimal radius gap. Then, by combining the critical radius gap and the optimal radius gap of the piston pair, we propose the CORG design method for the radius gap of the piston pair and obtain a dimensionless CORG constant that should be satisfied in the design of the radius gap of the piston pair. In framework of the CORG design method, it can not only ensure that the total power loss of a single piston pair is minimized but also prevent the volumetric efficiency of the piston pair from being too low. Finally, the simulation model of the piston pair is built by AMESim software, and the correctness of the theoretical calculation results are further verified by comparing the simulation results with the theoretical calculation results. The CORG design method can further provide theoretical references for the design of the piston pair.

Real-time Self-calibration Method of Vehicle Camera Attitude Based on ANN

The research of the monocular vision ranging method has great research value in the field of intelligent vehicles. Camera calibration is an important step in a monocular vision ranging model. The accuracy of camera calibration directly determines the accuracy of ranging. Because the camera attitude may change during vehicle driving, it will have a certain impact on the accuracy of the ranging algorithm. Therefore, based on a monocular ranging model and focal length calibration method based on geometric transformation, a real-time camera attitude self-calibration method based on the width measurement model and ANN model is proposed in this paper. Firstly, the method takes the wheel width of the known vehicle type as a fixed value, takes the contact points between the two wheels of the front vehicle and the ground as the feature points, and brings them into the width measurement model to form constraints. However, the single formula formed by a single pair of feature points cannot solve the camera inclination of multiple dimensions at the same time, and it is difficult to solve the analytical solution of the complex formula. In this paper, the ANN model is proposed to fit and solve the formula, and a large number of data sets are obtained through experimental point distribution to train and test the model. The results show that the ranging accuracy of using this method to calibrate the camera tilt angle is unchanged compared to the previous measurement accuracy using sensors, meeting the ranging requirements

Development of a model for predicting the flash temperature in single asperity contact between TC4 titanium and Q235 steel

The friction hot surfaces generated by metal under low-speed friction is the main potential ignition source for explosive atmosphere, while the friction flash temperature is often much higher than the bulk temperature under the same conditions. Then the first to reach the ignition temperature of the combustible gas is the bulk temperature of the hot surface or the flash temperature of the contact of the asperities, which is worth studying. In view of this, by establishing a friction model, this paper conducts an in-depth study on the flash temperature of the asperities contact between the of TC4 titanium alloy and Q235 steel at the friction conditions of low speed and low load. According to the Hertz contact theory, the contact process of a single pair of asperities and the calculation method of the maximum flash temperature are analyzed, and the maximum flash temperature value is calculated using two assumptions. Combined with regression analysis, the mathematical model of the flash temperature with load and relative velocity is obtained. Under the same conditions, the maximum bulk temperature and flash temperature are calculated, so as to study the real effective ignition source of the gas at the friction conditions of low speed and low load.

Cryo-EM structure of human O-GlcNAcylation enzyme pair OGT-OGA complex

O-GlcNAcylation is a conserved post-translational modification that attaches N-acetyl glucosamine (GlcNAc) to myriad cellular proteins. In response to nutritional and hormonal signals, O-GlcNAcylation regulates diverse cellular processes by modulating the stability, structure, and function of target proteins. Dysregulation of O-GlcNAcylation has been implicated in the pathogenesis of cancer, diabetes, and neurodegeneration. A single pair of enzymes, the O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), catalyzes the addition and removal of O-GlcNAc on over 3,000 proteins in the human proteome. However, how OGT selects its native substrates and maintains the homeostatic control of O-GlcNAcylation of so many substrates against OGA is not fully understood. Here, we present the cryo-electron microscopy (cryo-EM) structures of human OGT and the OGT-OGA complex. Our studies reveal that OGT forms a functionally important scissor-shaped dimer. Within the OGT-OGA complex structure, a long flexible OGA segment occupies the extended substrate-binding groove of OGT and positions a serine for O-GlcNAcylation, thus preventing OGT from modifying other substrates. Conversely, OGT disrupts the functional dimerization of OGA and occludes its active site, resulting in the blocking of access by other substrates. This mutual inhibition between OGT and OGA may limit the futile O-GlcNAcylation cycles and help to maintain O-GlcNAc homeostasis.

Tailoring Photon Statistics with an Atom-Based Two-Photon Interferometer.

Controlling the photon statistics of light is paramount for quantum science and technologies. Recently, we demonstrated that transmitting resonant laser light past an ensemble of two-level emitters can result in a stream of single photons or excess photon pairs. This transformation is due to quantum interference between the transmitted laser light and the incoherently scattered photon pairs [Prasad etal., Nat. Photonics 14, 719 (2020)NPAHBY1749-488510.1038/s41566-020-0692-z]. Here, using the dispersion of the atomic medium, we actively control the relative quantum phase between these two components. We thereby realize a tunable two-photon interferometer and observe interference fringes in the normalized photon coincidence rate. When tuning the relative phase, the coincidence rate varies periodically, giving rise to a continuous modification of the photon statistics from antibunching to bunching. Beyond the fundamental insight that there exists a tunable quantum phase between incoherent and coherent light that dictates the photon statistics, our results lend themselves to the development of novel quantum light sources.

Liquid Metal Embrittlement Cracking in Uncoated Transformation-Induced Plasticity Steel during Consecutive Resistance Spot Welding

In the automotive production line, a single pair of electrodes is employed to produce hundreds of consecutive welds before undergoing dressing or replacement. In consecutive resistance spot welding (RSW) involving Zn-coated steels, the electrodes undergo metallurgical degradation, characterized by Cu-Zn alloying, which impacts the susceptibility to liquid metal embrittlement (LME) cracking. In the present investigation, the possibility of LME crack formation in uncoated TRIP steel joints during consecutive RSW (involving 400 welds in galvannealed and uncoated TRIP steels) was investigated. The results have shown that different Cu-Zn phases were formed on the electrode surface because of its contamination with Zn from the galvannealed coating. Therefore, during the welding of the uncoated TRIP steel, the heat generated at the electrode/sheet interface would result in the melting of the Cu-Zn phases, thereby exposing the uncoated steel surface to molten Zn and Cu, leading to LME cracking. The cracks exhibited a maximum length of approximately 30 µm at Location A (weld center) and 50 µm at Location B (shoulder of the weld). The occurrence and characteristics of the cracks differed depending on the location as the number of welds increased due to the variation in Zn content. Type A cracks did not form when the number of welds was less than 280. Several cracks with a total length of approximately 30 μm were suddenly formed between 280 and 400 welds. On the other hand, type B cracks began to appear after 40 welds. However, the number and size of these exhibited inconsistency as the number of welds increased. Overall, the results have shown that small LME cracks can form even in uncoated steels during consecutive welding of Zn-coated and uncoated steel joints.

Eyes of love: Java sparrows increase eye ring conspicuousness when pair-bonded.

Conspicuous facial features, such as blushing in primates, can communicate social/emotional/physiological states in animals. However, the role of bare facial features is less well studied in birds than in humans or primates. We investigate the Java sparrow, which is characterised by conspicuous rings of swollen and blushed bare skin around the eye. Eye rings show no clear sex difference, although the swelling is associated with breeding. Java sparrows are socially monogamous, with mutual courtships and long-term pair-bonding. Therefore, it is plausible that eye rings function in within-pair communication. Specifically, do eye rings reflect psychophysiological conditions after pair formation? We assessed variations in ring thickness in pair-bonded birds and compared them with single birds and pairs of non-bonded individuals. Over the 12-week experimental period, pair-bonded males and females had an increased ring thickness, unlike the controls. We suggest eye rings convey breeding motivations or serve as fertility signals. This would be of great importance for ensuring reproductive synchrony in tropical birds like the Java sparrow. Our results contribute to understanding the evolution of facial ornamentation in birds, which was often overlooked in the past studies.