bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of upstream staggered cylinder on vortex-induced vibration responses of side-by-side cylinders in turbulent flow
Authors: Irawan Yosua Heru , Chiu Yu-Hao , Raza Syed Ahmad , Chern Ming-Jyh
Published: August 2023

A direct-forcing immersed boundary method with large-eddy simulation was used to simulate the phenomenon of the vortex-induced vibration (VIV) of multiple cylinders in a flow field. The present study analyzed the influence of an upstream stationary cylinder on the vibration behavior of two side-by-side cylinders downstream in a staggered position. The latter two side-by-side cylinders were allowed to vibrate in the cross-flow direction. By using different center-to-center distances between cylinders, damping ratios, mass ratios, Reynolds numbers, and diameters of the upstream stationary cylinder, the VIV response and energy conversion efficiency of the vibrating cylinders were studied. The results showed that the amplitude and efficiency of the vibrating cylinders are significantly enhanced at reduced velocity UR*≥6.0 when compared with a single vibrating cylinder. The maximum values of amplitude and efficiency can be shifted and enhanced, respectively, by adjusting the mass ratio and damping ratio. Reducing the diameter of the stationary upstream cylinder can effectively improve efficiency, especially in the lock-in region.
Effects of hump deflection angle on streamwise vortex instability over a yawed cone at Mach 6
Authors: Zhang Bin , Tu Guohua , Chen Xi , Yang Qiang , Chen Jianqiang , Li Xiaohu
Published: August 2023

This paper investigates the influence of three-dimensional smooth humps with varying deflection angles (φ) on the linear stability of streamwise vortices over a yawed cone with a 7° half-angle at a 6° angle-of-attack, free-stream Mach number of 6, and unit Reynolds number of 1.0×107/m. The steady laminar flow is obtained using direct numerical simulations. The eN method based on global stability theory is used to predict the transition location of the streamwise vortices along the centerline on the leeward side of the cone. The results reveal that φ plays a significant role in the outward vortex generation location, with smaller values of φ effectively delaying the outward vortex generation. Moreover, there is a qualitative relationship between the instability of the streamwise vortices and the inward/outward vortex structure characteristics of the base flow over a yawed cone. Namely, the transition delay effect of the streamwise vortices is proportional to the delay in the generation location of the outward vortex, which provides insights into the control of the transition induced by streamwise vortices. In particular, the configuration based on a hump with φ=9° and a height of 0.57 times the local boundary layer thickness delays the transition by approximately 38.2% at the critical N-factor (Ntr=12.5) without significantly increasing the instability of the inner mode.
Measuring the anisotropic permittivity tensor of DyScO3 to 110 GHz
Authors: Bergmann Florian , Papac Meagan C. , Jungwirth Nicholas R. , Bosworth Bryan T. , Karpisz Tomasz , Enright Lucas , Osella Anna , Marksz Eric J. , Stelson Angela C. , Long Christian J. , Orloff Nathan D.
Published: August 2023

DyScO3 (DSO) is an attractive substrate on which to grow epitaxial thin films with extraordinary materials physics. However, its highly anisotropic permittivity makes some measurements exceedingly difficult: For instance, its permittivity tensor has not yet been fully characterized at millimeter-wave frequencies. While there are methods to characterize anisotropic permittivity at millimeter-wave frequencies, there are very few methods those are suitable for the small lateral dimensions that DyScO3 can be grown in. To overcome this lack in the material characterization, we tested an on-wafer method based on coplanar waveguides to measure the full anisotropic permittivity tensor from 0.1 to 110 GHz. We characterized two orthogonal sets of coplanar waveguides fabricated on each of two substrates with (001) and (110) crystallographic orientations to resolve the full permittivity tensor. To validate our measurements, we compared our results to data from dc parallel plate capacitors and THz time-domain spectroscopy. Our measurements fill the need for measurements of the permittivity of DyScO3, while the methodology, more generally, enables quantitative characterization of anisotropic dielectrics.
Surfactant-influenced oil–water slip and flow in nanochannels studied by molecular dynamics and theoretical modeling
Authors: Liu Wenchuan , Jing Dengwei
Published: August 2023

This work uses molecular dynamics (MD) methods to investigate oil–water two-phase flow in hydrophilic nanochannels with surfactants adsorbed at the oil–water interface. We reveal two new discontinuous effects of nanoscale fluid flow: (i) the velocity distribution in the water layer is not a univariate function of the pressure gradient, and (ii) the apparent viscosity in the oil–water interface region is a function of surfactant concentration and pressure gradient. Based on the MD results, a layered theoretical model describing the discontinuous effects at the nanoscale is developed. The theoretical model provides quantitative two-dimensional functions for oil–water interface slip and fluid mass flux with pressure gradient and surfactant concentration. Surfactants significantly inhibit oil–water slip and reduce fluid mass flux. This study thus provides important insights into the theoretical and numerical models for shale or tight oil production predictions.
Physics-informed graph convolutional neural network for modeling fluid flow and heat convection
Authors: Peng Jiang-Zhou , Hua Yue , Li Yu-Bai , Chen Zhi-Hua , Wu Wei-Tao , Aubry Nadine
Published: August 2023

This paper introduces a novel surrogate model for two-dimensional adaptive steady-state thermal convection fields based on deep learning technology. The proposed model aims to overcome limitations in traditional frameworks caused by network types, such as the requirement for extensive training data, accuracy loss due to pixelated preprocessing of original data, and inability to predict information near the boundaries with precision. We propose a new framework that consists primarily of a physical-informed neural network (PINN) and a graph convolutional neural network (GCN). The GCN serves as the prediction module and predicts thermal convection in the two-dimensional computational domain by considering the mutual influence between unstructured nodes and their neighbors. On the other hand, the PINN acts as the physical constraint module of the framework by embedding the control equation of thermal convection into the loss function of the neural network, ensuring that the inference and prediction results of the GCN comply with the constraints of the control equation. The advantages of this framework lie in two aspects. First, the computation mechanism of the GCN is more in line with the actual evolution of temperature fields. Second, the PINN enhances the cognitive ability of the surrogate model toward the convection field information. It accurately describes the changes of temperature gradient information at the boundary position and reduces the model's demand for training data. To validate the advantages of the proposed model, we gradually analyzed the model's geometric adaptability and predictive accuracy from the single cylinder case to the double cylinder case. We also investigated the impact of the number of sampling points on model training and compared the model's prediction results with those of a purely data-driven model. The results show that the proposed model exhibits good geometric adaptability and stability. With only 20 training data, the mean error of the proposed model in predicting the velocity and temperature field is less than 1% and 0.6% for the single cylinder, and less than 2% and 1% for the double cylinder case, while the mean error of the purely data-driven GCN model in predicting the velocity and temperature field is 9.4% and 6.4% for the double cylinder case. These findings demonstrate the effectiveness of the proposed physics-informed graph convolutional neural network, allowing for more accurate prediction of fluid flow and heat convection using surrogate model.
Flying characterization of colliding partners by hyperfine splitting frequency of neutral paramagnetic atoms
Authors: Ishikawa Kiyoshi
Published: August 2023

The pseudopotentials and dispersion potentials are applied to a theoretical study of the hyperfine splitting frequencies of the ground-state paramagnetic hydrogen (H) and alkali-metal (Li, Na, K, Rb, and Cs) atoms in noble gases (He, Ne, Ar, Kr, and Xe). Using classical turning points for statistical averages, we find that numerical calculations based on second-order perturbation theory fit the measured frequency shifts well over a wide temperature range. The characteristic energy, pseudopotential height, and electric-dipole polarizability allow us to consistently determine the van der Waals radii and electron scattering lengths of noble-gas atoms. This study shows that the hyperfine splitting frequency of alkali-metal atoms is a good measure for investigating colliding partners.
Controlling sound waves in gradient spoof-fluid-spoof waveguides
Authors: Dong Daxing , Li Weimian , Li Xiao , Liu Jiaqing , Liu Youwen , Ji Hongli , Xu Yadong , Fu Yangyang
Published: August 2023

In this work, we theoretically and experimentally demonstrate that effective trapping, guiding, and manipulation of sound waves can be realized in spoof-fluid-spoof acoustic waveguides with gradient index modulation. Empowered by the abundant mode evolution physics between propagation waves and spoof acoustic surface waves in the gradient waveguide structure, various functional sound propagation phenomena, including broadband transmission, broadband reflection, Fabry–Pérot resonances, and Fano resonances, are unveiled. The underlying principle stems from the interplay of various mechanisms composed of gradient mode conversion, high-order mode resonances, and symmetry-protected bound states in the continuum. These effects can be effectively modulated through the manipulation of the fluid gap and doped defects within the waveguide structure. Our findings can offer possibilities for manipulating sound waves in a versatile manner and holding significant potential for various acoustic applications such as sensing, filtering, insulation, and wavefront engineering.
Regeneration mechanisms of oblique and streamwise vortices in oblique transition
Authors: Jiao Yuxin , Tao Jianjun
Published: August 2023

Oblique transition can be triggered by introducing componentwise optimal perturbations into a plane Couette flow. It is shown that in the middle stage of the transition, oblique vortices are generated again through transient spanwise velocity energy growth in the presence of developed streamwise streaks. In the following stage, streamwise independent kinetic energies of cross-streamwise velocities are intensified due to the nonlinear contribution caused by amplified oblique vortices together with the pressure transport, and the increased cross-stream velocity fluctuations can strengthen the lift-up effect. As a result, the streamwise vortices are formed again, and the streamwise streaks are even enhanced prior to their final breakdown to turbulence.
Electrically controlled hybrid superconductor–ferromagnet cell for high density cryogenic memory
Authors: Nevirkovets I. P. , Mukhanov O. A.
Published: August 2023

We report the fabrication and testing, at 4.2 K, of an S1IS2FS3 device, where S, F, and I denote a superconductor (Nb), a ferromagnetic material (Permalloy), and an insulator (AlOx), respectively. The F layer covers about one half of the top electrode of the S1IS2 Josephson junction and is positioned off-center. Electric current, Itr, along the S3 electrode can change the magnetization of the F layer in such a way that, for one direction of Itr, a magnetic flux penetrates the junction perpendicular to the layers, whereas for the opposite direction, the perpendicular magnetic flux can be removed. In the former state, the modulation pattern of the Josephson critical current, Ic, in the magnetic field, H, may acquire minimum near H = 0 and restores its usual shape with maximum in the second state. These states can be used for building a compact cryogenic memory compatible with single flux quantum electronics.
Line spectrum extraction method of underwater targets based on the polarization characteristic
Authors: Han Xue , Wang Yang , Liu Peng , Zhang Zihao
Published: August 2023

In order to suppress the environmental noise interference of underwater targets, a line spectrum extraction method is proposed based on the polarization characteristic of underwater acoustic signals received by a single vector sensor. In this paper, the polarization filtering function of a fourth-order cumulant diagonal slice is developed, and the fourth-order cumulant diagonal slice characteristic spectrum corresponding to the maximum singular value decomposition is used to extract the line spectrum. The simulation and experimental results show that the proposed method can extract the line spectrum signal adaptively, which has a good abatement effect on environmental noise interference.
Ultra-high baud rate VLF magnetoelectric antenna based on Rosen-type composite
Authors: Cheng Jiawei , Jiao Jie , Fu Shifeng , Jiang Tao , Wu Hanzhou , Fang Ze , Yuan Zhule , You Haoran , Sokolov Oleg , Ivanov Sergey , Bichurin Mirza , Wang Yaojin
Published: August 2023

Long-wave antennas are extensively used in special environment communications, such as underwater and underground applications, but the huge size of traditional electrical antennas restricts their applications. The emergent acoustically excited magnetoelectric (ME) antennas is expected to solve the portability problem. However, the contradiction between the radiation intensity and modulation rate (i.e., baud rate) of ME antenna remains an obstacle to its development. Here, we propose a very low frequency (VLF, 3–30 kHz) ME antenna based on a Rosen-type magnetostrictive-piezoelectric ME composite, which collaboratively optimizes both radiation intensity and transmission rate. The radiation intensity and efficiency of the proposed ME antenna were, respectively, two and three orders of magnitude higher than those of a same-sized loop antenna. A VLF communication system based on the Rosen-type ME antenna utilized amplitude shift keying (ASK) modulation was demonstrated. The system achieved an ultra-high baud rate of up to 2 kbaud (i.e., 2 kbps bit rate), confirming the feasibility of this approach.
Utilisation of in-consultation supervisor assistance in general practice training and personal cost to trainees: a cross-sectional study
Authors: Sturman Nancy , Tapley Amanda , Holliday Elizabeth , Fielding Alison , Davey Andrew , van Driel Mieke , Ball Jean , FitzGerald Kristen , Spike Neil , Magin Parker
Published: August 2023

Aim The aim of the study was to establish whether two previously described barriers to effective in-consultation assistance-seeking by general practice (GP) vocational specialist trainees (ie concern about patient impressions of their competence, and discomfort presenting to supervisors in front of patients) influenced the frequency of trainee in-consultation assistance-seeking from their supervisor. Methods This was a cross-sectional study nested in the Registrar Clinical Encounters in Clinical Training ongoing cohort study of Australian GP trainees. Trainee participants completed contemporaneous records of 60 consecutive patient consultations, including whether supervisory assistance was sought. Trainees also completed a cross-sectional survey including items eliciting their beliefs about patient impressions and their own discomfort in seeking in-consultation supervisory assistance. These were factors of interest in multivariable logistic regression analyses; the outcome factor in both regression models was the seeking of in-consultation supervisory assistance. Results In 2018, 778 trainees (778/876, response rate 89%) completed the cross-sectional survey. No association was found between the odds of in-consultation help-seeking and perceived decrease in patient impressions of trainee competence (OR = 1.09; 95% CI: 0.91, 1.31; P = 0.36) or higher comfort presenting outside patients’ hearing (OR = 0.9; 95% CI: 0.77, 1.05; P = 0.19). Discussion Contrary to expected utility models of help-seeking, trainees may not consider personal discomfort or impression management to be important enough, compared to patient safety and other considerations, to influence decisions regarding in-consultation help-seeking. Clinical supervisors should, nevertheless, consider the potential personal costs to trainees and maintain trainee self-esteem and confidence by providing in-consultation assistance in front of patients as comfortably and effectively as possible.
Developing a model for primary care quality improvement success: a comparative case study in rural, urban and Kaupapa Māori organisations
Authors: Cullen Jane , Childerhouse Paul , Jayamaha Nihal , McBain Lynn
Published: August 2023

Introduction Primary care is under pressure to achieve accessible, equitable, quality health care, while being increasingly under resourced. There is a need to understand factors that influence quality improvement (QI) to support a high-performing primary care system. Literature highlights the impact of context on QI but there is little primary care research on this topic. Aim This qualitative case study research seeks to discover the contextual factors influencing QI in primary care, and how the relationships between contextual factors, the QI initiative, and the implementation process influence outcomes. Methods The Consolidated Framework for Implementation Research was used to frame this qualitative study exploring primary care experiences in depth. Six sites were selected to provide a sample of rural, urban and Kaupapa Māori settings. Qualitative data was collected via semi-structured interviews and compared and contrasted with the organisational documents and data provided by participants. Results Cases reported success in achieving improved outcomes for patients, practices, and staff. Strong internal cultures of ‘Clan’ and ‘Adhocracy’ typologies supported teamwork, distributed leadership, and a learning climate to facilitate iterative sensemaking activities. To varying degrees, external network relationships provided resources, knowledge, and support. Discussion Organisations were motivated by a combination of patient/community need and organisational culture. Network relationships assisted to varying degrees depending on need. Engaged and distributed leadership based on teamwork was observed, where leadership was shared and emerged at different levels and times as the need arose. A learning climate was supported to enable iterative sensemaking activities to achieve success.
Medication reconciliation and discharge communication from hospital to general practice: a quantitative analysis
Authors: Gusmeroli Melinda , Perks Stephen , Bates Nicole
Published: August 2023

Background The aim of this study was to assess the quality of effective discharge communication to primary practice from a hospital that uses ieMR (integrated electronic Medical Record), a complete electronic prescribing/medical record platform. Methods A retrospective quantitative analysis of 232 discharge encounters from a major tertiary hospital assessed the discharge summary quality; timeliness, completeness and medication information. Results Median time to discharge summary was 1 day. 22.0% of discharge summaries were incomplete at 30 days post discharge and 44.5% of discharge summaries were incomplete at 30 days post discharge if discharged on a weekend compared to weekday (P-value = 0.001). Rates of medication reconciliation were completed at approximately 35% at each point of the patient stay and 56.9% of patients had a GP discharge summary listing discharge medications. However, if certain progressive steps were completed (i.e. Home Medications recorded in ieMR, Discharge Reconciliation in ieMR, and Patient Discharge Medication Record in eLMs (Enterprise-wide Liaison Medication System)), then, the ‘Medications on Discharge’ was significantly more likely to be present in the discharge summary, at rates of 70.1%, 85.9%, and 98.6% respectively (P-value = 0.007, <0.001, <0.001). Conversely not doing these steps dropped rates of having medications listed in the discharge summary to 50.0%, 40.3% and 34.1% respectively. Conclusions This study assessed current discharge summary quality since the introduction of electronic medical records. It demonstrated the significant value of correct use of electronic programs, including performing all crucial steps of reconciliation. Targeted interventions in future studies that rectify the shortfalls in discharge communication are warranted.
Rethinking policies for pastoralists – governing the rangelands
Authors: Nori Michele , Scoones Ian
Published: August 2023

Policies and governance arrangements are relevant in shaping livelihoods in the pastoral regions of the world. Institutions and rules that enable access to land, markets and investment for pastoralists and those that regulate their participation in the political arena are critical in fostering or constraining livelihoods and the capacities to respond adaptively to uncertainties. Decades of misconceived narratives leading to distorted policies around pastoralism have significantly undermined the capacity of formal institutions, state agencies and development organisations to deal with the complexity of pastoral systems and eroded their legitimacy vis-à-vis herding communities. Despite more recent scientific and policy debates, new generations of civil servants, local authorities and development agents firmly believe that dismissing the pastoral lifestyle is the necessary prerequisite for a transition to modernity. This in turn nurtures patterns of marginalisation, grievance and instability. As pastoral regions have become the focus of new economic interests and competing socio-political agendas, these tensions can be easily manipulated. This paper assesses the political framework in pastoral areas in four regions, with the aim of understanding how this affects the livelihoods of local communities and the implications for local decision-making and the broader political arena.
Complexity of clay minerals and its effects on silicon dynamics in hypersaline coastal wetland soils, Brazil
Authors: Sartor Lucas Resmini , Andrade Gabriel Ramatis Pugliese , Ying Samantha C. , Graham Robert C. , Macedo Rodrigo Santana , Ferreira Tiago Osório
Published: August 2023

Context Tidal dynamics and high evaporative rates in hypersaline tidal flat (HTF) soils favour a range of clay reactions and the formation of complex clay assemblages. HTFs have a geochemical environment conducive to mineral reactions, and therefore, clay mineral alteration controls essential nutrients in coastal wetlands. Aims The crystallochemical characteristics of clay minerals from two HTFs were studied to provide insights into the complexity of fine clay assemblages in HTF soils and their effects on Si biogeochemistry. Methods The fine clay fraction (<0.2 μm) from these HTFs were investigated using X-ray diffraction (XRD) modelling, XRF, FTIR, TEM–EDS, and silicon sequential extractions. Key results The results have indicated the presence of endmembers and R0 mixed-layered minerals such as kaolinite, smectite, illite, kaolinite–smectite (K–S), kaolinite–illite (K–I), illite–smectite (I–S), and illite–vermiculite (I–V). In general, K–S was the dominant mineral in the samples, occurring in a range of kaolinite layers. Alteration of detrital kaolinite to other mixed-layered minerals occurs in soils, leading to silicon removal from the soil solution because of mineral genesis. There is Mg enrichment at the expense of Al in the samples, and bio-opal appears to be the source of Si for the kaolinite alteration process. Conclusions Our findings indicate that clay authigenesis is an important factor controlling Si dynamics in HTF soils, acting as a sink of Si during the formation of new clay phases. Implications Chemical reactions involving clay minerals are critical for deepening our understanding of the biogeochemistry of wetland soils.
Soil phosphorus and biomass carbon co-determine plantation soil organic carbon density: a case study in western Beijing, China
Authors: Wang Shiqiang , Guo Yanpei
Published: August 2023

Context Studies of afforestation have traditionally neglected the influences of plant microhabitats on the growth and carbon sink capacities of planted forests. Aims We investigated the potential mechanisms related to the relationship of afforestation elevation to soil organic carbon density (SOCD). Methods The carbon density of three plantation ecosystems and barren land soils were evaluated at two elevations in the Donglingshan Mountains of Beijing, with structural equation modelling and variation partitioning analyses used to identify the environmental factors that influenced the carbon densities of plantation ecosystems. Key results Afforestation elevation was related to the vegetation phenology of plantation forests. Specifically, growth periods at higher elevations were delayed relative to those at lower elevations, while different growth periods affected growth rate of diameter at breast height (RDBH), in addition to the carbon and nitrogen contents of ground surface litters. Consequently, lower elevation afforestation reduced the carbon sink capacity of coniferous plantation ecosystems in the study area. Lower plantation elevations were associated with significantly reduced RDBH values of Pinus tabuliformis. Further, biomass carbon density (BCD) and SOCD of Larix principis-rupprechtii plantations were significantly lower due to decreased elevations. Soil nitrogen concentrations, litter nitrogen density (LND), soil phosphorus concentrations, and BCD were the primary drivers of plantation SOCD. Conclusions Overall, different plantation elevations were associated with different vegetation phenologies and RDBH values, which further affected LND and BCD, thereby ultimately affecting variation of SOCD. Implications This study provides important insights into the selection of afforestation plots to maximise plantation carbon sequestration capacities.
Soil organic matter fractions under different land uses and soil classes in the Brazilian semi-arid region
Authors: dos Santos Crislâny Canuto , Medeiros Aldair de Souza , Araújo Victor Matheus Ferreira de , Maia Stoécio Malta Ferreira
Published: August 2023

Context Land use change (LUC) is considered one of the main factors associated with soil carbon (C) loss worldwide. Aim Evaluate changes in labile and non-labile soil organic matter (SOM) fractions in different land use systems – native vegetation (NV), agriculture with conventional cultivation (CC) and pasture (PA) – in five soil classes in the Brazilian semi-arid region. Methods Soil samples were collected to a depth of 100 cm, and soil C and nitrogen (N) content and stocks were determined and also stocks of labile (LC) and non-labile (NlC) C fractions. In addition, the Carbon Management Index (CMI) was used to evaluate soil health changes. Key results SOC stocks significantly decreased after conversion from NV to CC (by 23%; 0–30 cm) and PA (by 22%; 0–100 cm). Losses due to LUC were greater in the LC than the NlC fraction, and this was reflected in the CMI reducing by 37% for PA and 57% for CC in the 0–100 cm layer. Regarding the different soil classes, LUC reduced SOC stocks only in the Luvisol, Planosol and Leptosol classes, while in the LC fraction, changes were observed in Acrisols, Cambisols and Planosols. Conclusions Clearing NV areas for CC systems and PA reduced the SOC stocks and SOM fractions and, consequently, decreased soil quality. Implications These findings underscore the importance of considering the quality of SOM when evaluating LUC impacts on SOC stocks in the different classes of soil in the Brazilian semi-arid region.
Predicting burn severity for integration with post-fire debris-flow hazard assessment: a case study from the Upper Colorado River Basin, USA
Authors: Wells Adam G. , Hawbaker Todd J. , Hiers J. Kevin , Kean Jason , Loehman Rachel A. , Steblein Paul F.
Published: August 2023

Background Burn severity significantly increases the likelihood and volume of post-wildfire debris flows. Pre-fire severity predictions can expedite mitigation efforts because precipitation contributing to these hazards often occurs shortly after wildfires, leaving little time for post-fire planning and management. Aim The aim of this study was to predict burn severity using pre-fire conditions of individual wildfire events and estimate potential post-fire debris flow to unburned areas. Methods We used random forests to model dNBR from pre-fire weather, fuels, topography, and remotely sensed data. We validated our model predictions against post-fire observations and potential post-fire debris-flow hazard estimates. Key results Fuels, pre-fire weather, and topography were important predictors of burn severity, although predictor importance varied between fires. Post-fire debris-flow hazard rankings from predicted burn severity (pre-fire) were similar to hazard assessments based on observed burn severity (post-fire). Conclusion Predicted burn severity can serve as an input to post-fire debris-flow models before wildfires occur, antecedent to standard post-fire burn severity products. Assessing a larger set of fires under disparate conditions and landscapes will be needed to refine predictive models. Implications Burn severity models based on pre-fire conditions enable the prediction of fire effects and identification of potential hazards to prioritise response and mitigation.
Building transformers from neurons and astrocytes
Authors: Kozachkov Leo , Kastanenka Ksenia V. , Krotov Dmitry
Published: August 2023

Glial cells account for between 50% and 90% of all human brain cells, and serve a variety of important developmental, structural, and metabolic functions. Recent experimental efforts suggest that astrocytes, a type of glial cell, are also directly involved in core cognitive processes such as learning and memory. While it is well established that astrocytes and neurons are connected to one another in feedback loops across many timescales and spatial scales, there is a gap in understanding the computational role of neuron–astrocyte interactions. To help bridge this gap, we draw on recent advances in AI and astrocyte imaging technology. In particular, we show that neuron–astrocyte networks can naturally perform the core computation of a Transformer, a particularly successful type of AI architecture. In doing so, we provide a concrete, normative, and experimentally testable account of neuron–astrocyte communication. Because Transformers are so successful across a wide variety of task domains, such as language, vision, and audition, our analysis may help explain the ubiquity, flexibility, and power of the brain’s neuron–astrocyte networks.
Ceramide as an endothelial cell surface receptor and a lung-specific lipid vascular target for circulating ligands
Authors: Staquicini Daniela I. , Cardó-Vila Marina , Rotolo Jimmy A. , Staquicini Fernanda I. , Tang Fenny H. F. , Smith Tracey L. , Ganju Aditya , Schiavone Carmine , Dogra Prashant , Wang Zhihui , Cristini Vittorio , Giordano Ricardo J. , Ozawa Michael G. , Driessen Wouter H. P. , Proneth Bettina , Souza Glauco R. , Brinker Lina M. , Noureddine Achraf , Snider Ashley J. , Canals Daniel , Gelovani Juri G. , Petrache Irina , Tuder Rubin M. , Obeid Lina M. , Hannun Yusuf A. , Kolesnick Richard N. , Brinker C. Jeffrey , Pasqualini Renata , Arap Wadih
Published: August 2023

The vascular endothelium from individual organs is functionally specialized, and it displays a unique set of accessible molecular targets. These serve as endothelial cell receptors to affinity ligands. To date, all identified vascular receptors have been proteins. Here, we show that an endothelial lung-homing peptide (CGSPGWVRC) interacts with C16-ceramide, a bioactive sphingolipid that mediates several biological functions. Upon binding to cell surfaces, CGSPGWVRC triggers ceramide-rich platform formation, activates acid sphingomyelinase and ceramide production, without the associated downstream apoptotic signaling. We also show that the lung selectivity of CGSPGWVRC homing peptide is dependent on ceramide production in vivo. Finally, we demonstrate two potential applications for this lipid vascular targeting system: i) as a bioinorganic hydrogel for pulmonary imaging and ii) as a ligand-directed lung immunization tool against COVID-19. Thus, C16-ceramide is a unique example of a lipid-based receptor system in the lung vascular endothelium targeted in vivo by circulating ligands such as CGSPGWVRC.
Climate change–induced stress disrupts ectomycorrhizal interaction networks at the boreal–temperate ecotone
Authors: Fernandez Christopher W. , Mielke Louis , Stefanski Artur , Bermudez Raimundo , Hobbie Sarah E. , Montgomery Rebecca A. , Reich Peter B. , Kennedy Peter G.
Published: August 2023

The interaction networks formed by ectomycorrhizal fungi (EMF) and their tree hosts, which are important to both forest recruitment and ecosystem carbon and nutrient retention, may be particularly susceptible to climate change at the boreal–temperate forest ecotone where environmental conditions are changing rapidly. Here, we quantified the compositional and functional trait responses of EMF communities and their interaction networks with two boreal (
Pinus banksiana
and
Betula papyrifera
) and two temperate (
Pinus strobus
and
Quercus macrocarpa
) hosts to a factorial combination of experimentally elevated temperatures and reduced rainfall in a long-term open-air field experiment. The study was conducted at the B4WarmED (Boreal Forest Warming at an Ecotone in Danger) experiment in Minnesota, USA, where infrared lamps and buried heating cables elevate temperatures (ambient, +3.1 °C) and rain-out shelters reduce growing season precipitation (ambient, ~30% reduction). EMF communities were characterized and interaction networks inferred from metabarcoding of fungal-colonized root tips. Warming and rainfall reduction significantly altered EMF community composition, leading to an increase in the relative abundance of EMF with contact-short distance exploration types. These compositional changes, which likely limited the capacity for mycelial connections between trees, corresponded with shifts from highly redundant EMF interaction networks under ambient conditions to less redundant (more specialized) networks. Further, the observed changes in EMF communities and interaction networks were correlated with changes in soil moisture and host photosynthesis. Collectively, these results indicate that the projected changes in climate will likely lead to significant shifts in the traits, structure, and integrity of EMF communities as well as their interaction networks in forest ecosystems at the boreal–temperate ecotone.
Threading-the-Needle: Compatibilization of HDPE/
i
PP blends with butadiene-derived polyolefin block copolymers
Authors: Shen Liyang , Gorbea Gabriela Diaz , Danielson Evan , Cui Shuquan , Ellison Christopher J. , Bates Frank S.
Published: August 2023

Management of the plastic industry is a momentous challenge, one that pits enormous societal benefits against an accumulating reservoir of nearly indestructible waste. A promising strategy for recycling polyethylene (PE) and isotactic polypropylene (
i
PP), constituting roughly half the plastic produced annually worldwide, is melt blending for reformulation into useful products. Unfortunately, such blends are generally brittle and useless due to phase separation and mechanically weak domain interfaces. Recent studies have shown that addition of small amounts of semicrystalline PE-
i
PP block copolymers (ca. 1 wt%) to mixtures of these polyolefins results in ductility comparable to the pure materials. However, current methods for producing such additives rely on expensive reagents, prohibitively impacting the cost of recycling these inexpensive commodity plastics. Here, we describe an alternative strategy that exploits anionic polymerization of butadiene into block copolymers, with subsequent catalytic hydrogenation, yielding E and X blocks that are individually melt miscible with PE and
i
PP, where E and X are poly(ethylene-
ran
-ethylethylene) random copolymers with 6 wt% and 90 wt% ethylethylene repeat units, respectively. Cooling melt blended mixtures of PE and
i
PP containing 1 wt% of the triblock copolymer EXE of appropriate molecular weight, results in mechanical properties competitive with the component plastics. Blend toughness is obtained through interfacial topological entanglements of the amorphous X polymer and semicrystalline
i
PP, along with anchoring of the E blocks through cocrystallization with the PE homopolymer. Significantly, EXE can be inexpensively produced using currently practiced industrial scale polymerization methods, offering a practical approach to recycling the world’s top two plastics.
The weakness of senescent dermal fibroblasts
Authors: Rebehn Lydia , Khalaji Samira , KleinJan Fenneke , Kleemann Anja , Port Fabian , Paul Patrick , Huster Constantin , Nolte Ulla , Singh Karmveer , Kwapich Lisa , Pfeil Jonas , Pula Taner , Fischer-Posovszky Pamela , Scharffetter-Kochanek Karin , Gottschalk Kay-E.
Published: August 2023

Skin is the largest human organ with easily noticeable biophysical manifestations of aging. As human tissues age, there is chronological accumulation of biophysical changes due to internal and environmental factors. Skin aging leads to decreased elasticity and the loss of dermal matrix integrity via degradation. The mechanical properties of the dermal matrix are maintained by fibroblasts, which undergo replicative aging and may reach senescence. While the secretory phenotype of senescent fibroblasts is well studied, little is known about changes in the fibroblasts biophysical phenotype. Therefore, we compare biophysical properties of young versus proliferatively aged primary fibroblasts via fluorescence and traction force microscopy, single-cell atomic force spectroscopy, microfluidics, and microrheology of the cytoskeleton. Results show senescent fibroblasts have decreased cytoskeletal tension and myosin II regulatory light chain phosphorylation, in addition to significant loss of traction force. The alteration of cellular forces is harmful to extracellular matrix homeostasis, while decreased cytoskeletal tension can amplify epigenetic changes involved in senescence. Further exploration and detection of these mechanical phenomena provide possibilities for previously unexplored pharmaceutical targets against aging.
WASF3 disrupts mitochondrial respiration and may mediate exercise intolerance in myalgic encephalomyelitis/chronic fatigue syndrome
Authors: Wang Ping-yuan , Ma Jin , Kim Young-Chae , Son Annie Y. , Syed Abu Mohammad , Liu Chengyu , Mori Mateus P. , Huffstutler Rebecca D. , Stolinski JoEllyn L. , Talagala S. Lalith , Kang Ju-Gyeong , Walitt Brian T. , Nath Avindra , Hwang Paul M.
Published: August 2023

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is characterized by various disabling symptoms including exercise intolerance and is diagnosed in the absence of a specific cause, making its clinical management challenging. A better understanding of the molecular mechanism underlying this apparent bioenergetic deficiency state may reveal insights for developing targeted treatment strategies. We report that overexpression of
Wiskott-Aldrich Syndrome Protein Family Member 3
(
WASF3
), here identified in a 38-y-old woman suffering from long-standing fatigue and exercise intolerance, can disrupt mitochondrial respiratory supercomplex formation and is associated with endoplasmic reticulum (ER) stress. Increased expression of
WASF3
in transgenic mice markedly decreased their treadmill running capacity with concomitantly impaired respiratory supercomplex assembly and reduced complex IV levels in skeletal muscle mitochondria. WASF3 induction by ER stress using endotoxin, well known to be associated with fatigue in humans, also decreased skeletal muscle complex IV levels in mice, while decreasing WASF3 levels by pharmacologic inhibition of ER stress improved mitochondrial function in the cells of the patient with chronic fatigue. Expanding on our findings, skeletal muscle biopsy samples obtained from a cohort of patients with ME/CFS showed increased WASF3 protein levels and aberrant ER stress activation. In addition to revealing a potential mechanism for the bioenergetic deficiency in ME/CFS, our study may also provide insights into other disorders associated with fatigue such as rheumatic diseases and long COVID.
Focused ultrasound–mediated brain genome editing
Authors: Lao Yeh-Hsing , Ji Robin , Zhou Joyce K. , Snow Kathy J. , Kwon Nancy , Saville Ethan , He Siyu , Chauhan Shradha , Chi Chun-Wei , Datta Malika S. , Zhang Hairong , Quek Chai Hoon , Cai S. Sarah , Li Mingqiang , Gaitan Yaned , Bechtel Lawrence , Wu Shih-Ying , Lutz Cathleen M. , Tomer Raju , Murray Stephen A. , Chavez Alejandro , Konofagou Elisa E. , Leong Kam W.
Published: August 2023

Gene editing in the brain has been challenging because of the restricted transport imposed by the blood–brain barrier (BBB). Current approaches mainly rely on local injection to bypass the BBB. However, such administration is highly invasive and not amenable to treating certain delicate regions of the brain. We demonstrate a safe and effective gene editing technique by using focused ultrasound (FUS) to transiently open the BBB for the transport of intravenously delivered CRISPR/Cas9 machinery to the brain.
Near-infrared voltage-sensitive dyes based on chromene donor
Authors: Yan Ping , Acker Corey D. , Biasci Valentina , Judge Giuliana , Monroe Alexa , Sacconi Leonardo , Loew Leslie M.
Published: August 2023

Voltage-sensitive dyes (VSDs) are used to image electrical activity in cells and tissues with submillisecond time resolution. Most of these fast sensors are constructed from push–pull chromophores whose fluorescence spectra are modulated by the electric field across the cell membrane. It was found that the substitution of naphthalene with chromene produces a 60 to 80 nm red-shift in absorption and emission spectra while maintaining fluorescence quantum efficiency and voltage sensitivity. One dye was applied to ex vivo murine heart with excitation at 730 nm, by far the longest wavelength reported in voltage imaging. This VSD resolves cardiac action potentials in single trials with 12% ΔF/F per action potential. The well-separated excitation spectra between these long-wavelength VSDs and channelrhodopsin (ChR2) enabled monitoring of action potential propagation in ChR2 hearts without any perturbation of electrical dynamics. Importantly, by employing spatially localized optogenetic manipulation, action potential dynamics can be assessed in an all-optical fashion with no artifact related to optical cross-talk between the reporter and actuator. These new environmentally sensitive chromene-based chromophores are also likely to have applications outside voltage imaging.
Ranking mobility and impact inequality in early academic careers
Authors: Sun Ye , Caccioli Fabio , Livan Giacomo
Published: August 2023

How difficult is it for an early career academic to climb the ranks of their discipline? We tackle this question with a comprehensive bibliometric analysis of 57 disciplines, examining the publications of more than 5 million authors whose careers started between 1986 and 2008. We calibrate a simple random walk model over historical data of ranking mobility, which we use to 1) identify which strata of academic impact rankings are the most/least mobile and 2) study the temporal evolution of mobility. By focusing our analysis on cohorts of authors starting their careers in the same year, we find that ranking mobility is remarkably low for the top- and bottom-ranked authors and that this excess of stability persists throughout the entire period of our analysis. We further observe that mobility of impact rankings has increased over time, and that such rise has been accompanied by a decline of impact inequality, which is consistent with the negative correlation that we observe between such two quantities. These findings provide clarity on the opportunities of new scholars entering the academic community, with implications for academic policymaking.
A synergy between site-specific and transient interactions drives the phase separation of a disordered, low-complexity domain
Authors: Mohanty Priyesh , Shenoy Jayakrishna , Rizuan Azamat , Mercado-Ortiz José F. , Fawzi Nicolas L. , Mittal Jeetain
Published: August 2023

TAR DNA-binding protein 43 (TDP-43) is involved in key processes in RNA metabolism and is frequently implicated in many neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal dementia. The prion-like, disordered C-terminal domain (CTD) of TDP-43 is aggregation-prone, can undergo liquid-liquid phase separation (LLPS) in isolation, and is critical for phase separation (PS) of the full-length protein under physiological conditions. While a short conserved helical region (CR, spanning residues 319-341) promotes oligomerization and is essential for LLPS, aromatic residues in the flanking disordered regions (QN-rich, IDR1/2) are also found to play a critical role in PS and aggregation. Compared with other phase-separating proteins, TDP-43 CTD has a notably distinct sequence composition including many aliphatic residues such as methionine and leucine. Aliphatic residues were previously suggested to modulate the apparent viscosity of the resulting phases, but their direct contribution toward CTD phase separation has been relatively ignored. Using multiscale simulations coupled with in vitro saturation concentration (c
sat
) measurements, we identified the importance of aromatic residues while also suggesting an essential role for aliphatic methionine residues in promoting single-chain compaction and LLPS. Surprisingly, NMR experiments showed that transient interactions involving phenylalanine and methionine residues in the disordered flanking regions can directly enhance site-specific, CR-mediated intermolecular association. Overall, our work highlights an underappreciated mode of biomolecular recognition, wherein both transient and site-specific hydrophobic interactions act synergistically to drive the oligomerization and phase separation of a disordered, low-complexity domain.