bluuebunny/crossref_metadata_2025 huggingface dataset:
Enumeration of Moiré patterns of a hexagonal twisted bilayer: Applications to intercalated transition metals
Authors: Ciesler Matthew , West Damien , Zhang Shengbai
Published: October 2023

A real-space method using generating integers is used to determine possible commensurate lattice Moiré patterns for a bilayer of two equal hexagonal lattices, which can in principle be extended to lattice mismatched bilayers. These Moiré patterns can be classified by a pair of relatively prime integers (n,m), wherein a rotation θ(n,m) of the top hexagonal lattice maps its lattice vector (n,m) to (m,n) of the bottom lattice. Within this formulation, the area of the commensurate supercell is proportional to (n2+m2+nm) and the number of coincident lattice sites per supercell is given by (n−m)2. Taking bilayer boron nitride (BN) as an example, we present how to systematically generate Moiré patterns and explore the differences in local chemistry in the interstitial region by impurity intercalation. Systematic calculations of the properties of intercalated 3d transition metals were performed in an h-BN (4,3) bilayer, corresponding to a rotation of 9.43 degrees. These calculations reveal that local symmetry in the intercalated region significantly affect the energetics and magnetization of the intercalated species. These results highlight that Moiré pattern physics is not limited to optoelectronic/electronic phenomena, such as interfacial exciton formation or magic angle superconductivity, but it also produces chemical and magnetic atomic site selectivity, which may play important roles in adsorption, catalysis, or quantum information.
Ultrafast pulse duration measurement method of near-infrared pulses for a broad range of wavelengths using two-photon absorption in a liquid and fluorescent dye solution
Authors: Syed Rafeeq , Uiterwaal Cornelis J. G. J.
Published: October 2023

A novel characterization method to measure the pulse duration of ultrafast near-IR pulses is introduced, which uses simple tabletop optics, is relatively inexpensive, and is expected to work in a broad wavelength range. Our diagnostic tool quantitatively characterizes the laser pulse duration of any near-IR wavelength assuming a Gaussian pulse shape with a linear chirp. We negatively prechirp near-IR pulses with a home-built broadband pulse compressor (BPC) and send this prechirped beam through a cell filled with a low-molar solution of a fluorescent dye in a liquid. After two-photon absorption, this dye fluoresces in the visible, and we record this visible signal as a function of the propagation distance in the liquid cell. We calibrate the group velocity dispersion (GVD) of our home-built BPC device against the known GVD of the compressor of our 800 nm laser and confirm this value using geometric considerations. Now knowing the GVD of BPC and the recorded visible signal for various amounts of negative chirp, let us extract the smallest pulse duration of the near-IR pulse from this visible signal. As a useful corollary, our analysis also enables the direct measurement of the GVD for liquids and the indirect measurement of the absorption coefficient for liquids in the near-IR range, in contrast to indirect GVD measurements that rely on methods such as the double derivative of the refractive index.
A method to reduce open optical path noise interference in two-dimensional gas detection of farmland
Authors: Gao Hua , Li Qi , Zhang Dashan , Liu Lu , Gao Yanwei , Liao Juan , Tang Qi-Xing
Published: October 2023

The two-dimensional distribution method based on the laser spectrum is widely used in the reconstruction of two-dimensional temperature fields or concentration fields. However, the existing methods are all based on small-scale measurements. In large-scale spatial detection of farmland, the detection accuracy cannot reach the expected result due to the long optical path and the noise of various frequencies brought by environmental factors such as vibration, temperature, and other interfering gases. Aiming at the above-mentioned problems, this paper proposes a method to reduce open optical path noise interference in two-dimensional gas detection of farmland to improve detection accuracy. The signal denoising approach combines variational modal decomposition with the SG filtering algorithm to decompose, smooth out, and rebuild the detection signal. In addition, we built a two-dimensional detection system based on an open optical path. Throughout experimental validation, the proposed method outperformed the traditional method by 24% and 19%, respectively, in terms of the fitting degree and fitting effect of the gas absorption curve.
Investigating the effect of H+-ion irradiation on layered α-MoO3 flakes by defect engineering
Authors: Kumar Ravindra , Mishra Vikash , Dixit Tejendra , Sarangi S. N. , Samal D. , Miryala Muralidhar , Nayak Pramoda K. , Rao M. S. Ramachandra
Published: October 2023

Ion irradiation is a versatile and convenient tool for modifying the optical, electrical, and catalytic properties of two-dimensional (2D) materials through controlled induction of impurities and defects. The behavior of 2D materials under ion irradiation is interesting, which needs to be explored in the contest of their optoelectronic applications. In the present work, we have reported the effect of H+-ion irradiation on layered α-MoO3 flakes by defect engineering. Initially, the α-MoO3 crystals were synthesized using the physical vapor deposition technique followed by mechanical exfoliation of an as-grown crystal to obtain α-MoO3 flakes of different thicknesses. Then, the exfoliated flakes were exposed to H+-ion/proton irradiation with a fluence of 1 × 1016 ions/cm2 using a 30 keV source. After irradiation, new photoluminescence (PL) emission peaks were observed at different positions in the range of ∼2.4–1.9 eV, which was found to be absent in pristine flakes. Raman studies revealed non-uniform oxygen vacancy distribution in H+-ion irradiated α-MoO3 flakes, which affected the PL peak positions. Additionally, first-principle calculations and Bader charge analysis were performed to identify the origin of the new PL peaks. Our findings indicate that oxygen vacancies positioning at different locations of the α-MoO3 lead to the emergence of new absorption peaks within the range of ∼2.2–1.25 eV, which is consistent with our experimental findings. The present study gives insight into exploring the use of ion-irradiated α-MoO3 in optoelectronics applications with tunable properties.
Terahertz wave emission with 1.5 μm pump from photoconductive antenna using stacked Er-doped-InAs quantum dot layers with ultrafast carrier relaxation
Authors: Minami Yasuo , Abe Hiromutsu , Lu Xiangmeng , Kumagai Naoto , Kitada Takahiro
Published: October 2023

We fabricated a photoconductive antenna (PCA) with Er-doped InAs quantum dot (QD) layers on a GaAs substrate and demonstrated THz wave generation with 1.5 μm pump. In terahertz time-domain spectroscopy (THz-TDS), PCAs require high mobility and short lifetimes of photocarriers since the carriers need to respond rapidly to optical pulses for broad THz generation and detection with a high time resolution. In this study, to achieve PCA operation at an optical communication wavelength band of 1.5 μm, a substrate for a PCA was fabricated using stacked Er-doped-InAs QD layers. Then, photocurrent measurements were performed to observe optical absorption in the 1.5 μm band. The results indicated the high capability of the PCA for THz wave generation and detection, in fact, which enabled us to generate the THz wave in the 1.5 μm band optical system.
Chimera states in a chain of superdiffusively coupled neurons
Authors: Fateev I. , Polezhaev A.
Published: October 2023

Two- and three-component systems of superdiffusion equations describing the dynamics of action potential propagation in a chain of non-locally interacting neurons with Hindmarsh–Rose nonlinear functions have been considered. Non-local couplings based on the fractional Laplace operator describing superdiffusion kinetics are found to support chimeras. In turn, the system with local couplings, based on the classical Laplace operator, shows synchronous behavior. For several parameters responsible for the activation properties of neurons, it is shown that the structure and evolution of chimera states depend significantly on the fractional Laplacian exponent, reflecting non-local properties of the couplings. For two-component systems, an anisotropic transition to full incoherence in the parameter space responsible for non-locality of the first and second variables is established. Introducing a third slow variable induces a gradual transition to incoherence via additional chimera states formation. We also discuss the possible causes of chimera states formation in such a system of non-locally interacting neurons and relate them with the properties of the fractional Laplace operator in a system with global coupling.
Learning a simulation-based visual policy for real-world peg in unseen holes
Authors: Xie Liang , Yu Hongxiang , Xu Kechun , Yang Tong , Wang Minhang , Lu Haojian , Xiong Rong , Wang Yue
Published: October 2023

This paper proposes a learning-based visual peg-in-hole that enables training with several shapes in simulation and adapting to arbitrary unseen shapes in the real world with minimal sim-to-real cost. The core idea is to decouple the generalization of the sensory-motor policy from the design of a fast-adaptable perception module and a simulated generic policy module. The framework consists of a segmentation network (SN), a virtual sensor network (VSN), and a controller network (CN). Concretely, the VSN is trained to measure the pose of the unseen shape from a segmented image. After that, given the shape-agnostic pose measurement, the CN is trained to achieve a generic peg-in-hole. Finally, when applying to real unseen holes, we only have to fine-tune the SN required by the simulated VSN + CN. To further minimize the transfer cost, we propose to automatically collect and annotate the data for the SN after one-minute human teaching. Simulated and real-world results are presented under the configuration of eye-to/in-hand. An electric vehicle charging system with the proposed policy inside achieves a 10/10 success rate in 2–3 s, using only hundreds of auto-labeled samples for the SN transfer.
Signal response enhanced by partial time delay in anormal diffusive coupled bistable oscillators
Authors: Tang Caihong , Wang Maosheng , Xu Fei , Huang Shoufang , Lu Xiaojie , Zhang Jiqian
Published: October 2023

The effect of a partial time delay on the response to external weak input signals in a bistable oscillator with anormal diffusive coupling was studied. Periodic resonance or anti-resonance in the signal response with time delay was observed, and the resonance period equals the period of the external input signal. Specifically, for the negative mean-field density parameter, the signal response can be improved through time delay, which is a resonance phenomenon. Conversely, for the positive mean-field density parameter, no such enhancement effect was observed, suggesting the presence of an anti-resonance phenomenon. As the probability of a partial time delay increases, the width of the time delay of the optimal signal response becomes narrower. When the probability of a partial time delay is large enough, the response of the system is optimal only when the time delay closely approximates integer or half-integer multiples of the external signal period. These numerical findings provide a new approach for weak signal detection that could be applied to the extraction of weak feature information within relevant fields.
The effect of infrared push pulse on the relaxed exciton in single-component organic solar cells
Authors: Zhang Maomao , Lu Qiuxia , Liu Xiaojing , Gao Kun , An Zhong
Published: October 2023

Ultrafast pump-push-probe/photocurrent experiments have confirmed that free charges can be spontaneously generated in single-component organic solar cells. A deeper understanding of the experimental results is expected to further modulate the charge yield. Herein, the effect of an infrared push pulse on the relaxed exciton in conjugated polymers is theoretically studied. We find that the relaxed exciton can be pushed into different hot excitons depending on the energy of this infrared pulse. In particular, the dynamics of the transition from localized to delocalized excitons is explicitly presented. Moreover, we attempt to demonstrate that the delocalization effect of hot exciton is favorable for charge generation by introducing a driving field. The results suggest that the strength of the driving field and timescale required for the dissociation of hot exciton is significantly reduced compared to this relaxed exciton. Finally, the influence of the photoexcitation conditions on the charge generation is discussed to further elucidate the effect of hot exciton delocalization. Overall, this work has the potential to provide further information for the analysis and control of charge generation by hot exciton dissociation.
Phenotypic variation of Kikuyu grass (Cenchrus clandestinus) across livestock production farms in Colombian highlands is explained by management and environment rather than genetic diversity
Authors: Castillo Sierra Javier , Cerón-Souza Ivania , Avellaneda Avellaneda Yesid , Mancipe Muñoz Edgar Augusto , Vargas Martínez Juan de Jesús
Published: October 2023

Context Kikuyu grass (Cenchrus clandestinus (Hochst. ex Chiov.) Morrone) is native to the Central African highlands and was introduced to Colombia in 1928 to feed animals. Despite its low genetic diversity and proven genetic clonality, this species has shown broad phenotypic variation and has become the primary forage resource for livestock production systems in the Colombian highlands. However, it is necessary to determine whether genetic diversity should be considered when designing management programs. Aims We aimed to determine which variables among location, altitude and population genetic structure explain the phenotypic variation of Kikuyu grass samples across livestock farms at high altitudes. Methods We used principal component analysis, redundancy analysis and partial redundancy analysis to understand the contribution of three explanatory variables (three high-altitude ranges, six locations and two or five genetic clusters) and 30 covariables (pasture management and soil traits of each farm) to explain 18 phenotypic variables of 146 Kikuyu grass samples from high-altitude livestock farms in Colombia. Key results All explanatory variables and covariables explained 39.1–41.5% of the phenotypic variation of Kikuyu grass in Colombia. However, the effect of the genetic structure based on two or five clusters was negligible. By comparison, locality, altitude and 13 covariables of productive system management and soil traits were significant. Conclusions Genetic population structure was insignificant in explaining the phenotypic variation of Kikuyu grass in Colombia. Implications Future research on Kikuyu grass in Colombia should focus on farm management variables and soil trait analyses.
Leaf water relations and osmotic adjustment of Canada Western Red Spring wheat cultivars subjected to drought
Authors: Sharma Gopal , Brar Gurcharn S. , Knipfer Thorsten
Published: October 2023

For wheat (Triticum aestivum), sustained crop yield at limited soil water availability has been linked to osmotic adjustment (OA) – a physiological mechanism that aids maintenance of leaf hydration status, turgor (P) and growth. ‘Canada Western Red Spring’ (CWRS) wheat cultivars are typically grown in rainfed areas with milder climates, but ongoing climate change is increasesing the frequency and intensity of drought events. The overarching goal of this study was to elucidate if commercially used CWRS cultivars (‘Superb’, ‘Stettler’, ‘AAC Viewfield’) have the ability for leaf OA. Measurements of leaf water relation parameters (water potential, Ψ; solute potential, Ψs; stomatal conductance, gs; relative water content, RWC) showed that all three cultivars reached zero P (= Ψ – Ψs) at a leaf Ψ of −1.1 MPa. Prior to that, P maintenance in ‘Superb’ and ‘AAC Viewfield’ was associated with a significant reduction in leaf Ψs and OA contributed 0.53 MPa (‘Superb’) and 0.73 MPa (‘AAC Viewfield’). Our data analyses provided no support for the existence of OA in ‘Stettler’. Under water deficit, leaf gs was significantly higher in ‘AAC Viewfield’ compared to ‘Stettler’; it was intermediate in ‘Superb’. Together, drought tolerance in CWRS wheat cultivars is most likely linked to the degree of OA.
Fluctuating selection maintains distinct species phenotypes in an ecological community in the wild
Authors: Stroud James T. , Moore Michael P. , Langerhans R. Brian , Losos Jonathan B.
Published: October 2023

Species’ phenotypic characteristics often remain unchanged over long stretches of geological time. Stabilizing selection—in which fitness is highest for intermediate phenotypes and lowest for the extremes—has been widely invoked as responsible for this pattern. At the community level, such stabilizing selection acting individually on co-occurring species is expected to produce a rugged fitness landscape on which different species occupy distinct fitness peaks. However, even with an explosion of microevolutionary field studies over the past four decades, evidence for persistent stabilizing selection driving long-term stasis is lacking. Nonetheless, biologists continue to invoke stabilizing selection as a major factor explaining macroevolutionary patterns. Here, by directly measuring natural selection in the wild, we identified a complex community-wide fitness surface in which fourAnolislizard species each occupy a distinct fitness peak close to their mean phenotype. The presence of local fitness optima within species, and fitness valleys between species, presents a barrier to adaptive evolutionary change and acts to maintain species differences through time. However, instead of continuously operating stabilizing selection, we found that species were maintained on these peaks by the combination of many independent periods among which selection fluctuated in form, strength, direction, or existence and in which stabilizing selection rarely occurred. Our results suggest that lack of substantial phenotypic evolutionary change through time may be the result of selection, but not persistent stabilizing selection as classically envisioned.
Greatly enhanced risk to humans as a consequence of empirically determined lower moist heat stress tolerance
Authors: Vecellio Daniel J. , Kong Qinqin , Kenney W. Larry , Huber Matthew
Published: October 2023

As heatwaves become more frequent, intense, and longer-lasting due to climate change, the question of breaching thermal limits becomes pressing. A wet-bulb temperature (Tw) of 35 °C has been proposed as a theoretical upper limit on human abilities to biologically thermoregulate. But, recent—empirical—research using human subjects found a significantly lower maximum Twat which thermoregulation is possible even with minimal metabolic activity. Projecting future exposure to this empirical critical environmental limit has not been done. Here, using this more accurate threshold and the latest coupled climate model results, we quantify exposure to dangerous, potentially lethal heat for future climates at various global warming levels. We find that humanity is more vulnerable to moist heat stress than previously proposed because of these lower thermal limits. Still, limiting warming to under 2 °C nearly eliminates exposure and risk of widespread uncompensable moist heatwaves as a sharp rise in exposure occurs at 3 °C of warming. Parts of the Middle East and the Indus River Valley experience brief exceedances with only 1.5 °C warming. More widespread, but brief, dangerous heat stress occurs in a +2 °C climate, including in eastern China and sub-Saharan Africa, while the US Midwest emerges as a moist heat stress hotspot in a +3 °C climate. In the future, moist heat extremes will lie outside the bounds of past human experience and beyond current heat mitigation strategies for billions of people. While some physiological adaptation from the thresholds described here is possible, additional behavioral, cultural, and technical adaptation will be required to maintain healthy lifestyles.
Adenylate kinase 9 is essential for sperm function and male fertility in mammals
Authors: O’Callaghan Elena , Navarrete-Lopez Paula , Štiavnická Miriama , Sánchez José M. , Maroto Maria , Pericuesta Eva , Fernández-González Raul , O’Meara Ciara , Eivers Bernard , Kelleher Margaret M. , Evans Ross D. , Mapel Xena M. , Lloret-Villas Audald , Pausch Hubert , Balastegui-Alarcón Miriam , Avilés Manuel , Sanchez-Rodriguez Ana , Roldan Eduardo R. S. , McDonald Michael , Kenny David A. , Fair Sean , Gutiérrez-Adán Alfonso , Lonergan Patrick
Published: October 2023

Despite passing routine laboratory tests for semen quality, bulls used in artificial insemination exhibit significant variation in fertility. Routine analysis of fertility data identified a dairy bull with extreme subfertility (10% pregnancy rate). To characterize the subfertility phenotype, a range of in vitro, in vivo, and molecular assays were carried out. Sperm from the subfertile bull exhibited reduced motility and severely reduced caffeine-induced hyperactivation compared to controls. Ability to penetrate the zona pellucida, cleavage rate, cleavage kinetics, and blastocyst yield after IVF or AI were significantly lower than in control bulls. Whole-genome sequencing from semen and RNA sequencing of testis tissue revealed a critical mutation in adenylate kinase 9 (
AK9
) that impaired splicing, leading to a premature termination codon and a severely truncated protein. Mice deficient in AK9 were generated to further investigate the function of the gene; knockout males were phenotypically indistinguishable from their wild-type littermates but produced immotile sperm that were incapable of normal fertilization. These sperm exhibited numerous abnormalities, including a low ATP concentration and reduced motility. RNA-seq analysis of their testis revealed differential gene expression of components of the axoneme and sperm flagellum as well as steroid metabolic processes. Sperm ultrastructural analysis showed a high percentage of sperm with abnormal flagella. Combined bovine and murine data indicate the essential metabolic role of AK9 in sperm motility and/or hyperactivation, which in turn affects sperm binding and penetration of the zona pellucida. Thus, AK9 has been found to be directly implicated in impaired male fertility in mammals.
Ancient Maya reservoirs, constructed wetlands, and future water needs
Authors: Lucero Lisa J.
Published: October 2023

The Classic Maya (c. 250 to 900 CE) in the tropical southern lowlands of Central America dealt with water scarcity during annual dry seasons and periods of climate instability via sophisticated urban reservoir systems they relied on for over a thousand years. Surface water is limited because typically rain percolates through the karstic terrain. I posit that Maya reservoirs functioned as do constructed wetlands (CWs) at present. Still-water systems like CWs and Maya reservoirs can become stagnant and nonpotable due to the build-up of nutrients that promote algal growth. Stagnant waters also serve as breeding grounds for mosquitoes that spread endemic diseases. CWs keep water clean via certain aquatic plants since all plants uptake nutrients (e.g., nitrogen, phosphorus) and decomposing plant matter supports microbial biofilms that break down nutrients. CWs also support diverse zooplankton that prey on pathogens and bacteria that assist to denitrify water. CWs do not require the use of chemicals or fossil fuels and after the initial labor-intensive output become self-cleaning and self-sufficient with some maintenance. I posit that the Maya used a diverse array of aquatic plants and other biota to keep water clean in the same manner as do CWs, which I demonstrate using evidence from excavations and settlement maps, sediment cores and current wetlands, and the iconographic and hieroglyphic records. The next step is to combine what we know about ancient Maya reservoirs in conjunction with what is currently known about CWs to better address future water needs.
Controllable synthesis of borophene aerogels by utilizing h-BN layers for high-performance next-generation batteries
Authors: Çiftçi Niyazi Okan , Şentürk Sevil Berrak , Sezen Yaren , Kaykusuz Süreyya Üstün , Long Hu , Ergen Onur
Published: October 2023

Borophene is emerging as a promising electrode material for Li, Na, Mg, and Ca ion batteries due to its anisotropic Dirac properties, high charge capacity, and low energy barrier for ion diffusion. However, practical synthesis of active and stable borophene remains challenging in producing electrochemical devices. Here, we introduce a method for borophene aerogels (BoAs), utilizing hexagonal boron nitride aerogels. Borophene grows between h-BN layers utilizing boron–boron bridges, as a nucleation site, where borophene forms monolayers mixed with sp
2
-sp
3
hybridization. This versatile method produces stable BoAs and is compatible with various battery chemistries. With these BoAs, we accomplish an important milestone to successfully fabricate high-performance next-generation batteries, including Na-ion (478 mAh g
–1
, at 0.5C, >300 cycles), Mg-ion (297 mAh g
–1
, at 0.5C, >300 cycles), and Ca-ion (332 mAh g
–1
, at 0.5C, >400 cycles), and Li-S batteries, with one of the highest capacities to date (1,559 mAh g
–1
, at 0.3C, >1,000 cycles).
Identifying microscopic factors that influence ductility in disordered solids
Authors: Xiao Hongyi , Zhang Ge , Yang Entao , Ivancic Robert , Ridout Sean , Riggleman Robert , Durian Douglas J. , Liu Andrea J.
Published: October 2023

There are empirical strategies for tuning the degree of strain localization in disordered solids, but they are system-specific and no theoretical framework explains their effectiveness or limitations. Here, we study three model disordered solids: a simulated atomic glass, an experimental granular packing, and a simulated polymer glass. We tune each system using a different strategy to exhibit two different degrees of strain localization. In tandem, we construct structuro-elastoplastic (StEP) models, which reduce descriptions of the systems to a few microscopic features that control strain localization, using a machine learning-based descriptor, softness, to represent the stability of the disordered local structure. The models are based on calculated correlations of softness and rearrangements. Without additional parameters, the models exhibit semiquantitative agreement with observed stress–strain curves and softness statistics for all systems studied. Moreover, the StEP models reveal that initial structure, the near-field effect of rearrangements on local structure, and rearrangement size, respectively, are responsible for the changes in ductility observed in the three systems. Thus, StEP models provide microscopic understanding of how strain localization depends on the interplay of structure, plasticity, and elasticity.
Predicting the attention of others
Authors: Ziman Kirsten , Kimmel Sarah C. , Farrell Kathryn T. , Graziano Michael S. A.
Published: October 2023

As social animals, people are highly sensitive to the attention of others. Seeing someone else gaze at an object automatically draws one’s own attention to that object. Monitoring the attention of others aids in reconstructing their emotions, beliefs, and intentions and may play a crucial role in social alignment. Recently, however, it has been suggested that the human brain constructs a predictive model of other people’s attention that is far more involved than a moment-by-moment monitoring of gaze direction. The hypothesized model learns the statistical patterns in other people’s attention and extrapolates how attention is likely to move. Here, we tested the hypothesis of a predictive model of attention. Subjects saw movies of attention displayed as a bright spot shifting around a scene. Subjects were able to correctly distinguish natural attention sequences (based on eye tracking of prior participants) from altered sequences (e.g., played backward or in a scrambled order). Even when the attention spot moved around a blank background, subjects could distinguish natural from scrambled sequences, suggesting a sensitivity to the spatial–temporal statistics of attention. Subjects also showed an ability to recognize the attention patterns of different individuals. These results suggest that people possess a sophisticated model of the normal statistics of attention and can identify deviations from the model. Monitoring attention is therefore more than simply registering where someone else’s eyes are pointing. It involves predictive modeling, which may contribute to our remarkable social ability to predict the mind states and behavior of others.
Progenitor division and cell autonomous neurosecretion are required for rod photoreceptor sublaminar positioning
Authors: Gurdita Akshay , Pham Truong Victor Q. B. , Dolati Parnian , Juric Matey , Tachibana Nobuhiko , Liu Zhongda C. , Ortín-Martínez Arturo , Ibrahimi Mostafa , Pokrajac Nenad T. , Comanita Lacrimioara , Pacal Marek , Huang Mengjia , Sugita Shuzo , Bremner Rod , Wallace Valerie A.
Published: October 2023

Migration is essential for the laminar stratification and connectivity of neurons in the central nervous system. In the retina, photoreceptors (PRs) migrate to positions according to birthdate, with early-born cells localizing to the basal-most side of the outer nuclear layer. It was proposed that apical progenitor mitoses physically drive these basal translocations non-cell autonomously, but direct evidence is lacking, and whether other mechanisms participate is unknown. Here, combining loss- or gain-of-function assays to manipulate cell cycle regulators (Sonic hedgehog, Cdkn1a/p21) with an in vivo lentiviral labelling strategy, we demonstrate that progenitor division is one of two forces driving basal translocation of rod soma. Indeed, replacing Shh activity rescues abnormal rod translocation in retinal explants. Unexpectedly, we show that rod differentiation also promotes rod soma translocation. While outer segment function or formation is dispensable,
Crx
and SNARE-dependent synaptic function are essential. Thus, both non-cell and cell autonomous mechanisms underpin PR soma sublaminar positioning in the mammalian retina.
Adaptor protein-3 produces synaptic vesicles that release phasic dopamine
Authors: Jain Shweta , Yee Andrew G. , Maas James , Gierok Sarah , Xu Hongfei , Stansil Jasmine , Eriksen Jacob , Nelson Alexandra B. , Silm Katlin , Ford Christopher P. , Edwards Robert H.
Published: October 2023

The burst firing of midbrain dopamine neurons releases a phasic dopamine signal that mediates reinforcement learning. At many synapses, however, high firing rates deplete synaptic vesicles (SVs), resulting in synaptic depression that limits release. What accounts for the increased release of dopamine by stimulation at high frequency? We find that adaptor protein-3 (AP-3) and its coat protein VPS41 promote axonal dopamine release by targeting vesicular monoamine transporter VMAT2 to the axon rather than dendrites. AP-3 and VPS41 also produce SVs that respond preferentially to high-frequency stimulation, independent of their role in axonal polarity. In addition, conditional inactivation of VPS41 in dopamine neurons impairs reinforcement learning, and this involves a defect in the frequency dependence of release rather than the amount of dopamine released. Thus, AP-3 and VPS41 promote the axonal polarity of dopamine release but enable learning by producing a distinct population of SVs tuned specifically to high firing frequency that confers the phasic release of dopamine.
A non-pheromone GPCR is essential for meiosis and ascosporogenesis in the wheat scab fungus
Authors: Ding Mingyu , Cao Shulin , Xu Daiying , Xia Aliang , Wang Zeyi , Wang Wanshan , Duan Kaili , Wu Chenyu , Wang Qinhu , Liang Jie , Wang Diwen , Liu Huiquan , Xu Jin-Rong , Jiang Cong
Published: October 2023

Meiosis is essential for generating genetic diversity and sexual spores, but the regulation of meiosis and ascosporogenesis is not clear in filamentous fungi, in which dikaryotic and diploid cells formed inside fruiting bodies are not free living and independent of pheromones or pheromone receptors. In this study, Gia1, a non-pheromone GPCR (G protein-coupled receptor) with sexual-specific expression in
Fusarium graminearum
, is found to be essential for ascosporogenesis. The
gia1
mutant was normal in perithecium development, crozier formation, and karyogamy but failed to undergo meiosis, which could be partially rescued by a dominant active mutation in
GPA1
and activation of the Gpmk1 pathway.
GIA1
orthologs have conserved functions in regulating meiosis and ascosporogenesis in Sordariomycetes.
GIA1
has a paralog,
GIP1
, in
F. graminearum
and other Hypocreales species which is essential for perithecium formation.
GIP1
differed from
GIA1
in expression profiles and downstream signaling during sexual reproduction. Whereas the C-terminal tail and IR3 were important for intracellular signaling, the N-terminal region and EL3 of Gia1 were responsible for recognizing its ligand, which is likely a protein enriched in developing perithecia, particularly in the
gia1
mutant. Taken together, these results showed that
GIA1
encodes a non-pheromone GPCR that regulates the entry into meiosis and ascosporogenesis via the downstream Gpmk1 MAP kinase pathway in
F. graminearum
and other filamentous ascomycetes.
Water bend–libration as a cellular Raman imaging probe of hydration
Authors: Ramos Sashary , Lee Jennifer C.
Published: October 2023

Water is a ubiquitous and vital component of living systems. Hydration, which is the interaction between water and intracellular biomolecules, plays an important role in cellular processes. However, it is technically challenging to study water structure within cells directly. Here, we demonstrate the utility and power of the water bend–libration combination band as a unique Raman spectral imaging probe of cellular hydration. Hydration maps reveal distinct water environments within subcellular compartments (e.g., nucleolus and lipid droplet) due to the spectral sensitivity of this coupled vibrational band. Spectroscopic studies using the water bend–libration are broadly applicable, offering the potential to capture the chemical complexity of hydration in numerous systems.
Regulatory T cells control Staphylococcus aureus and disease severity of cutaneous leishmaniasis
Authors: Singh Tej Pratap , Farias Amorim Camila , Lovins Victoria M. , Bradley Charles W. , Carvalho Lucas P. , Carvalho Edgar M. , Grice Elizabeth A. , Scott Phillip
Published: October 2023

Cutaneous leishmaniasis causes alterations in the skin microbiota, leading to pathologic immune responses and delayed healing. However, it is not known how these microbiota-driven immune responses are regulated. Here, we report that depletion of Foxp3+ regulatory T cells (Tregs) in Staphylococcus aureus–colonized mice resulted in less IL-17 and an IFN-γ–dependent skin inflammation with impaired S. aureus immunity. Similarly, reducing Tregs in S. aureus–colonized and Leishmania braziliensis–infected mice increased IFN-γ, S. aureus, and disease severity. Importantly, analysis of lesions from L. braziliensis patients revealed that low FOXP3 gene expression is associated with high IFNG expression, S. aureus burden, and delayed lesion resolution compared to patients with high FOXP3 expression. Thus, we found a critical role for Tregs in regulating the balance between IL-17 and IFN-γ in the skin, which influences both bacterial burden and disease. These results have clinical ramifications for cutaneous leishmaniasis and other skin diseases associated with a dysregulated microbiome when Tregs are limited or dysfunctional.
Intensity-Dependent Dipole Phase in High-Order Harmonic Interferometry
Authors: Wang 王 Li 力 , Xiao 肖 Fan 凡 , Song 宋 Pan 盼 , Tao 陶 Wenkai 文凯 , Sun 孙 Xu 旭 , Wang 王 Jiacan 家灿 , Zheng 郑 Zhigang 志刚 , Zhao 赵 Jing 晶 , Wang 王 Xiaowei 小伟 , Zhao 赵 Zengxiu 增秀
Published: October 2023

High-order harmonics are ideal probes to resolve the attosecond dynamics of strong-field recollision processes. An easy-to-implement phase mask is utilized to covert the Gaussian beam to TEM01 transverse electromagnetic mode, allowing the realization of two-source interferometry of high-order harmonics. We experimentally measure the intensity dependence of dipole phase directly with high-order harmonic interferometry, in which the driving laser intensity can be precisely adjusted. The classical electron excursion simulations reproduce the experimental findings quite well, demonstrating that Coulomb potential plays subtle roles on movement of electrons for harmonics near the ionization threshold. This work is of great importance for precision measurements of ultrafast dynamics in strong-field physics.
Winding real and order-parameter spaces via lump solitons of spinor BEC on sphere
Authors: He Yan , Chien Chih-Chun
Published: October 2023

The three condensate wavefunctions of a F = 1 spinor Bose–Einstein condensate on a spherical shell can map the real space to the order-parameter space that also has a spherical geometry, giving rise to topological excitations called lump solitons. The homotopy of the mapping endows the lump solitons with quantized winding numbers counting the wrapping between the two spaces. We present several lump-soliton solutions to the nonlinear coupled equations minimizing the energy functional. The energies of the lump solitons with different winding numbers indicate coexistence of lumps with different winding numbers and a lack of advantage to break a higher-winding lump soliton into multiple lower-winding ones. Possible implications are discussed since the predictions are testable in cold-atom experiments.
Dual-antenna GNSS-aided robust MEMS IMU initial alignment under the earth-centered-earth-fixed frame
Authors: Zhang Siyu , Tang Weiming , Deng Chenlong , Li Yangyang
Published: October 2023

The micro-electro-mechanical system (MEMS), with its small size, low cost and low power, has attracted widespread attentions in recent year, and the initial alignment of the inertial measurement unit (IMU) is an indispensable step before the navigation computation. In the traditional alignment methods with only the velocity measurements, the yaw angle is subject to divergence under low dynamic scenarios, and the measurements are also susceptible to the external environments. Furthermore, the navigation frame (nframe) is usually chosen as the reference frame. Although intuitive, it is more computationally complex compared with the earth-centered-earth-fixed frame (eframe). Therefore, to improve the alignment performance and computational efficiency, a robust MEMS IMU initial alignment method with yaw assistance under theeframe is proposed. In this method, to address the issues of the yaw divergency and computational inefficiency in the traditional methods, the relationship between the yaw angle, derived from dual-antenna global navigation satellite system baseline solution, and IMU error is derived and incorporated into the state space model witheframe as the reference frame. Besides, a robust extended Kalman filtering is adopted to further improve the system’s performance of outlier resistance, whose robust factors are determined by the Institute of Geodesy and Geophysics Ⅲ model. To validate the performance of the proposed method, two field experiments with the velocity of about 0.7 m s−1and 1.5 m s−1was conducted, and the collected data were processed for contrastive analysis. The results show that the effectiveness of the proposed method at suppressing yaw angle divergence and improving the alignment accuracy by resisting outliers under low dynamic scenarios compared with the traditional method. Moreover, the elapsed time is reduced by about 11% when the reference frame in data processing is switched from thenframe to theeframe.
Application of local and global interval embedding algorithms in uncertain system processes
Authors: Li Ning , Ding Hua , Sun Xiaochun , Liu Zeping , Pu Guoshu
Published: October 2023

The data collected during the fault monitoring of industrial processes are often uncertain because of measurement noise, sensor error, and complex working environments. Currently, most of this uncertainty is transformed into interval-value data for processing. However, the traditional interval fault monitoring method (TIFMM) only considers the global information of the interval-valued data and only rarely considers the local neighborhood information, which can characterize the topological relationship between the interval-valued data points, so that the sample points with some nonlinear relationship still maintain this nonlinear relationship after dimensionality reduction. Therefore, to take into account both local and global information, a new interval-valued data projection algorithm called local and global interval embedding algorithms (LGIEA) is proposed in this paper. First, the measurement error estimation method, based on the principle of reasonable granularity, converts the imprecise variable measurement values into interval-value data that can reflect uncertainty. Then, an interval-matrix feature extraction method based on local and global information fusion, proposed in this paper, extracts process features by minimizing local scattering and maximizing global scattering of interval-valued data. Thereby, it preserves the optimal local neighborhood and global information in low-dimensional space. In addition, four statistical indicators and corresponding variable-contribution graphs have been defined to use online fault monitoring and fault variable identification. Finally, the superiority of the LGIEA was verified using simulation data of the Tennessee Eastman process and actual operating data of a shearer in an inclined-ditch coal mine. The experimental results show that, Compared with TIFMM such as midpoint-radius principal component analysis (PCA), complete information PCA and spectral radius-based interval PCA, proposed method significantly reduces the error alarm rate and the false monitoring rate and improves the accuracy of data classification. It also has better fault identification accuracy and robustness.
Quantum phase transitions in the anti-Jaynes-Cummings triangle model
Authors: Cheng Jia-Ming , Zhang Yong-Chang , Zhou Xiang-Fa , Zhou Zheng-Wei
Published: October 2023

We carefully investigate the comprehensive impact of atom-cavity interaction and artificial magnetic fields on quantum phase transitions of anti-Jaynes-Cummings triangle model in the infinite frequency limit. We discover that ground states of the optical field can be a gapped normal phase (NP) or three kinds of gapless superradiant phases with infinite degeneracy. When the atom-cavity coupling is weak, the optical field is in a NP, which is a vacuum with no photons. Otherwise, it will stay at one of the superradiant phases: a normal superradiant phase without photon currents and another two chiral superradiant phases with opposite photon currents. The former only breaks the continuous U(1) symmetry and its gapless excitations are normal Goldstone modes. Nevertheless, the latter, mainly induced by an external synthetic gauge field, break both the continuous U(1) symmetry and chiral symmetry, thereby corresponding gapless excitations are chiral Goldstone modes. In addition, we also propose a detecting scheme to distinguish these superradiant phases.
A quantum feature selection framework via ground state preparation
Authors: Wang Lu , Chen Zhao-Yun , Le Feng-Yu , Yu Zhi-Qian , Xue Cheng , Zhuang Xi-Ning , Yan Qing , Yang Yang , Wu Yu-Chun , Guo Guo-Ping
Published: October 2023

Traditional feature selection methods face the challenges of increasing time complexity and local optima. In previous works, many classical feature selection methods were accelerated through quantum algorithms. However, these approaches still inherit the constraints of these classical methods as they do not address the issue of local minima. Here, we propose a novel quantum feature selection framework based on the classifier’s result, which utilizes Hamiltonian encoding and a ground state preparation algorithm. Numerical experiments are conducted on real-world datasets from the finance and medicine domains. Moreover, the results demonstrate that the proposed method produces the same or better classification accuracy on the classifier than the original data without feature selection. Overall, our approach presents a promising solution to feature selection using quantum computing.
Effect of Matching Algorithm and Profile Shape on Pulsar Pulse Time of Arrival Uncertainties
Authors: Wang J. , Verbiest J. P. W. , Shaifullah G. M. , Yuan J. P.
Published: October 2023

For high-precision pulsar timing analysis and low-frequency gravitational wave detection, it is essential to accurately determine pulsar pulse times of arrival (ToAs) and associated uncertainties. To measure the ToAs and their uncertainties, various cross-correlation-based techniques can be employed. We develop methodologies to investigate the impact of the template-matching method, profile shape, signal-to-noise ratio of both template and observation on ToA uncertainties. These methodologies are then applied to data from the International Pulsar Timing Array. We demonstrate that the Fourier domain Markov chain Monte Carlo method is generally superior to other methods, while the Gaussian interpolation shift method outperforms other methods in certain cases, such as profiles with large duty cycles or smooth profiles without sharp features. However, it is important to note that our study focuses solely on ToA uncertainty, and the optimal method for determining both ToA and ToA uncertainty may differ.
A Comparison of Co-temporal Vector Magnetograms Obtained with HMI/SDO and SP/Hinode
Authors: Zhang Mei , Zhang Haocheng , Jiang Chengqing
Published: October 2023

Accurate measurement of magnetic fields is very important for understanding the formation and evolution of solar magnetic fields. Currently, there are two types of solar magnetic field measurement instruments: filter-based magnetographs and Stokes polarimeters. The former gives high temporal resolution magnetograms and the latter provides more accurate measurements of magnetic fields. Calibrating the magnetograms obtained by filter-based magnetographs with those obtained by Stokes polarimeters is a good way to combine the advantages of the two types. Our previous studies have shown that, compared to the magnetograms obtained by the Spectro-Polarimeter (SP) on board Hinode, those magnetograms obtained by both the filter-based Solar Magnetic Field Telescope (SMFT) of the Huairou Solar Observing Station and by the filter-based Michelson Doppler Imager (MDI) aboard SOHO have underestimated the flux densities in their magnetograms and systematic center-to-limb variations present in the magnetograms of both instruments. Here, using a sample of 75 vector magnetograms of stable alpha sunspots, we compare the vector magnetograms obtained by the Helioseismic and Magnetic Imager (HMI) aboard Solar Dynamics Observatory (SDO) with co-temporal vector magnetograms acquired by SP/Hinode. Our analysis shows that both the longitudinal and transverse flux densities in the HMI/SDO magnetograms are very close to those in the SP/Hinode magnetograms and the systematic center-to-limb variations in the HMI/SDO magnetograms are very minor. Our study suggests that using a filter-based magnetograph to construct a low spectral resolution Stokes profile, as done by HMI/SDO, can largely remove the disadvantages of the filter-type measurements and yet still possess the advantage of high temporal resolution.