bluuebunny/crossref_metadata_2025 huggingface dataset:
A wideband hybrid combiner design for ITER ion cyclotron radio frequency source
Authors: Jha Akhil , Palliwar Ajesh , Anand Rohit , Harikrishna J. V. S. , Patel Manoj , Dalicha Hrushikesh , Vasava Paresh , Soni Dipal , Verma Sriprakash , Suthar Gajendra , Mohan Kartik , Agarwal Rohit , Rajnish Kumar , Singh Raghuraj , Trivedi Rajesh. G. , Mukherjee Aparajita
Published: February 2023

The high-power radio frequency source for ion cyclotron heating and current drive of ITER tokamak consists of two identical 1.5 MW amplifier chains. These two chains will be combined using a wideband hybrid combiner with adequate coupling flatness, phase balance, return loss, and isolation response to generate 2.5 MW radio frequency (RF) power in the frequency range of 36 to 60 MHz. As part of the in-house development program at ITER-India, a wideband hybrid combiner with coupling flatness and return loss/isolation better than 0.4 and −25 dB, respectively, has been simulated. A detailed analysis for matched load performance of the hybrid combiner for the output power level of 3 MW as well as mismatched load performance for load power of 2.5 MW with voltage standing wave ratio 2.0 and 3.0 MW with voltage standing wave ratio 1.5 has been performed. Based on the simulation, a prototype model was in-house fabricated, and the simulated results have been validated experimentally in splitter and combiner mode. To evaluate performance as a combiner, two solid-state power amplifiers were combined through the prototype combiner for input power levels up to 2.5 kW on matched and mismatched load conditions. In the power splitter experiment, the RF power level up to 1.5 MW from a single amplifier chain was split through the prototype combiner to be dumped in the high power loads in the frequency range of 36 to 60 MHz.
An adaptive spatiotemporal fusion graph neural network for short-term power forecasting of multiple wind farms
Authors: Li Dan , Yang Fan , Miao Shuwei , Gan Yuelin , Yang Baohua , Zhang Yuanhang
Published: February 2023

Reliable short-term wind-power forecasting is crucial for the safe operation of power systems that accommodate large amount of wind power. With the development of large-scale wind power bases, wind power spatiotemporal correlations of multiple wind farms (WFs) can be used to improve short-term wind power prediction accuracy and efficiency. However, the time-varying and coupling characteristics of wind power spatiotemporal correlations present significant challenges for the accurate prediction of multi-WF power. In this paper, we propose an adaptive spatiotemporal fusion graph neural network for short-term power forecasting of multiple wind farms. Based on regional weather forecasts and historical wind power data, an adaptive directed graph is generated to model the dynamic spatial correlations between the WFs and the impact of regional weather factors on the wind power of different WFs. Graph convolution modules and temporal recursive modules are then alternately arranged to fuse the spatial and temporal features of wind power and to output the wind power prediction results for multiple WFs and time points. The case study results show that the proposed model outperforms the investigated baseline models in terms of prediction accuracy and that each model component has a unique contribution.
Evaluation of tight-binding DFT performance for the description of organic photochromes properties
Authors: Poidevin Corentin , Duplaix-Rata Gwenhaël , Costuas Karine , Fihey Arnaud
Published: February 2023

Photochromic molecules are widely studied and developed for their many potential applications. To optimize the required properties through theoretical models, a considerable chemical space is to be explored, and their environment in devices is to be accounted for.. To this end, cheap and reliable computational methods can be powerful tools to steer synthetic developments. As ab initio methods remain costly for extensive studies (in terms of the size of the system and/or number of molecules), semiempirical methods such as density functional tight-binding (TB) could offer a good compromise between accuracy computational cost. However, these approaches necessitate benchmarking on the families of compounds of interest. Thus, the aim of the present study is to evaluate the accuracy of several key features calculated with TB methods (DFTB2, DFTB3, GFN2-xTB, and LC-DFTB2) for three sets of photochromic organic molecules: azobenzene (AZO), norbornadiene/quadricyclane (NBD/QC), and dithienylethene (DTE) derivatives. The features considered here are the optimized geometries, the difference in energy between the two isomers (ΔE), and of the energies of the first relevant excited states. All the TB results are compared to those obtained with DFT methods and state-of-the-art electronic structure calculation methods: DLPNO-CCSD(T) for ground states and DLPNO-STEOM-CCSD for excited states. Our results show that, overall, DFTB3 is the TB method leading to the best results for the geometries and the ΔE values and can be used alone for these purposes for NBD/QC and DTE derivatives. Single point calculations at the r2SCAN-3c level using TB geometries allow circumventing the deficiencies of the TB methods in the AZO series. For electronic transition calculations, the range separated LC-DFTB2 method is the most accurate TB method tested for AZO and NBD/QC derivatives, in close agreement with the reference.
A generalized bodyforce scheme for lattice Boltzmann simulations of incompressible flow in complex geometries
Authors: Jettestuen Espen , Aursjø Olav , Vinningland Jan Ludvig , Hiorth Aksel
Published: February 2023

We present a general procedure for reducing compressibility effects in pressure driven lattice Boltzmann simulations involving complex geometries. We do this by introducing a preconditioning step for the flow system in order to reduce these often undesirable effects, rather than directly modifying the flow algorithm itself. The method consists of determining the geometry dependent contribution to a pressure field induced by a given set of pressure boundary conditions. We show that this may be done through solving a set of Laplace's equations that do not need re-evaluation during flow simulations. This preconditioning method is not limited to stationary flows but is directly applicable to time-varying flows, without any recalculation of the preconditioning step. In this paper, we apply the procedure to the lattice Boltzmann algorithm, but it may be utilized in any flow simulation algorithm based on artificial compressibility methods. The method is demonstrated in both stationary and non-stationary flow situations. This includes examples from flow in porous media and hemodynamics. All the presented examples are compared to conventional methods for implementing pressure driven flow in lattice Boltzmann. In all the examples, it is shown that the proposed method considerably reduces the undesirable features exhibited by the conventional methods.
Convective instabilities in a laminar shock-wave/boundary-layer interaction
Authors: Niessen Sébastien E. M. , Groot Koen J. , Hickel Stefan , Terrapon Vincent E.
Published: February 2023

Linear stability analyses are performed to study the dynamics of linear convective instability mechanisms in a laminar shock-wave/boundary-layer interaction at Mach 1.7. In order to account for all two-dimensional gradients elliptically, we introduce perturbations into an initial-value problem that are found as solutions to an eigenvalue problem formulated in a moving frame of reference. We demonstrate that this methodology provides results that are independent of the numerical setup, frame speed, and type of eigensolutions used as initial conditions. The obtained time-integrated wave packets are then Fourier-transformed to recover individual-frequency amplification curves. This allows us to determine the dominant spanwise wavenumber and frequency yielding the largest amplification of perturbations in the shock-induced recirculation bubble. By decomposing the temporal wave-packet growth rate into the physical energy-production processes, we provide an in-depth characterization of the convective instability mechanisms in the shock-wave/boundary-layer interaction. For the particular case studied, the largest growth rate is achieved in the near-vicinity of the bubble apex due to the wall-normal (productive) and streamwise (destructive) Reynolds-stress energy-production terms. We also observe that the Reynolds heat-flux effects are similar but contribute to a smaller extent.
Instability mechanism of shear-layered fluid in the presence of a floating elastic plate
Authors: Hossain Md. Mouzakkir , Tsai Chia-Cheng , Behera Harekrushna
Published: February 2023

In this study, linear stability analysis in the two-dimensional Cartesian coordinate system is used to analyze the flow dynamics underneath a large floating elastic plate over a slippery surface in the presence of external shear. For both viscous and inviscid flows, the Orr–Sommerfeld equation and the Rayleigh equation, respectively, are obtained using normal mode analysis. The Chebyshev collocation method is used to solve both equations numerically. Analysis of the growth rate and energy distributions is performed to understand the flow instability at various flow and structural parameters. The study reveals that the flow below the floating elastic plate dampens for larger uniform mass and structural rigidity in the viscous fluid. On the other hand, there is no effect of structural rigidity on the flow stability in the case of inviscid flow. However, the plate of larger uniform mass stabilizes the growing disturbance generated due to the externally imposed shear at the surface of the plate. The present study is analogous to the simple geographical model of external shearing on the surface of a large ice cover zone caused by atmospheric air. This study can be extended to understand the flow stability below other large floating structures like a floating island and a floating airport.
A neural network parametrized coagulation rate model for <3 nm titanium dioxide nanoclusters
Authors: Tamadate Tomoya , Yang Suo , Hogan Christopher J.
Published: February 2023

Coagulation is a key factor governing the size distribution of nanoclusters during the high temperature synthesis of metal oxide nanomaterials. Population balance models are strongly influenced by the coagulation rate coefficient utilized. Although simplified coagulation models are often invoked, the coagulation process, particularly for nanoscale particles, is complex, affected by the coagulating nanocluster sizes, the surrounding temperature, and potential interactions. Toward developing improved models of nanocluster and nanoparticle growth, we have developed a neural network (NN) model to describe titanium dioxide (TiO2) nanocluster coagulation rate coefficients, trained with molecular dynamics (MD) trajectory calculations. Specifically, we first calculated TiO2 nanocluster coagulation probabilities via MD trajectory calculations varying the nanocluster diameters from 0.6 to 3.0 nm, initial relative velocity from 20 to 700 m s−1, and impact parameter from 0.0 to 8.0 nm. Calculations consider dipole–dipole interactions, dispersion interactions, and short-range repulsive interactions. We trained a NN model to predict whether a given set of nanocluster diameters, impact parameter, and initial velocity would lead to the outcome of coagulation. The accuracy between the predicted outcomes from the NN model and the MD trajectory calculation results is >95%. We subsequently utilized both the NN model and MD trajectory calculations to examine coagulation rate coefficients at 300 and 1000 K. The NN model predictions are largely within the range 0.65–1.54 of MD predictions, and importantly NN predictions capture the local minimum coagulation rate coefficients observed in MD trajectory calculations. The NN model can be directly implemented in population balances of TiO2 formation.
Interface dewetting as a source of void formation and aggregation in phase change nanoscale actuators
Authors: Fang Xinyi , Masud Mohammad Ayaz , Piazza Gianluca , Bain James
Published: February 2023

This paper reports a phenomenon occurring between phase change material (PCM) germanium telluride (GeTe) and a thin encapsulation layer of alumina when the PCM undergoes the phase transformation, consistent with dewetting of the PCM from the surrounding alumina. Massive structural change, including formation of large voids, which take up to 21.9% of the initial GeTe volume after 10 000 phase change cycles is observed. Electrical and mechanical characterization of the structure confirms this interpretation. A rapid thermal annealing test of blanket films on alumina that demonstrates dewetting further validates this conjecture. The dewetting and associated gross material displacement can lead to an extraordinary actuation corresponding to a one-time 44 nm height change for a 178 nm GeTe thick layer. However, control of this phenomenon is required to build reliable actuators that do not suffer from rupture of the encapsulation layer.
The periodic secondary flow of Oldroyd-B fluids driven by direct electric field in a rectangular curved channel
Authors: Si Xinhui , Lei Xiaomin , Xu Bingrui , Li Botong , Zhu Jing , Cao Limei
Published: February 2023

The electro-osmotic flow of Oldroyd-B fluids in a 90° curved tube with a rectangular section under a direct electric field is numerically studied. By introducing elastic forces into the force balance of viscous, electric, and centrifugal forces, another secondary flow pattern is found in addition to the stable state for Newtonian fluids, i.e., the periodic oscillation state. In this oscillating state, the position of the maximum velocity periodically moves from the center to the position near the wall. Meanwhile, a symmetric vortex can be periodically observed in the streamline figures. The secondary flow oscillates when the Deborah number De or the dimensionless wall potential ψ is sufficiently large, and the oscillating frequency increases with a larger Deborah number De or a larger dimensionless wall potential ψ. A phase diagram of the secondary flow as it depends on the Deborah number De and the dimensionless wall potential ψ is presented. There is a critical Deborah number Decr for a given wall potential ψ, and the secondary flow become periodically oscillating at De>Decr. The critical Deborah number Decr decreases as the value of the dimensionless wall potential ψ increases. Moreover, the critical Deborah number should be larger than 0.2 even though the wall potential ψ further increases, i.e., Decr>0.2. At De≤0.2, the elastic forces are small, and the secondary flow is stable rather than oscillating similar to the phenomena of Newtonian fluids.
Collisional excitation of HCNH+ by He and H2: New potential energy surfaces and inelastic rate coefficients
Authors: Bop C. T. , Lique F.
Published: February 2023

Protonated molecules have been increasingly detected in the interstellar medium (ISM), and usually astrochemical models fail at reproducing the abundances derived from observational spectra. Rigorous interpretation of the detected interstellar emission lines requires prior calculations of collisional rate coefficients with H2 and He, i.e., the most abundant species in the ISM. In this work, we focus on the excitation of HCNH+ induced by collision with H2 and He. Therefore, we first calculate ab initio potential energy surfaces (PESs) using the explicitly correlated and standard coupled cluster method with single, double, and non-iterative triple excitation in conjunction with the augmented-correlation consistent-polarized valence triple zeta basis set. Both the HCNH+–H2 and HCNH+–He potentials are characterized by deep global minima of 1426.60 and 271.72 cm−1, respectively, and large anisotropies. From these PESs, we derive state-to-state inelastic cross sections for the 16 low-lying rotational energy levels of HCNH+ using the quantum mechanical close-coupling approach. The differences between cross sections due to ortho- and para-H2 impacts turn out to be minor. Using a thermal average of these data, we retrieve downward rate coefficients for kinetic temperatures of up to 100 K. As it could be anticipated, differences of up to two orders of magnitude exist between the rate coefficients induced by H2 and He collisions. We expect that our new collision data will help to improve the disagreement between abundances retrieved from observational spectra and astrochemical models.
A “short blanket” dilemma for a state-of-the-art neural network potential for water: Reproducing experimental properties or the physics of the underlying many-body interactions?
Authors: Zhai Yaoguang , Caruso Alessandro , Bore Sigbjørn Løland , Luo Zhishang , Paesani Francesco
Published: February 2023

Deep neural network (DNN) potentials have recently gained popularity in computer simulations of a wide range of molecular systems, from liquids to materials. In this study, we explore the possibility of combining the computational efficiency of the DeePMD framework and the demonstrated accuracy of the MB-pol data-driven, many-body potential to train a DNN potential for large-scale simulations of water across its phase diagram. We find that the DNN potential is able to reliably reproduce the MB-pol results for liquid water, but provides a less accurate description of the vapor–liquid equilibrium properties. This shortcoming is traced back to the inability of the DNN potential to correctly represent many-body interactions. An attempt to explicitly include information about many-body effects results in a new DNN potential that exhibits the opposite performance, being able to correctly reproduce the MB-pol vapor–liquid equilibrium properties, but losing accuracy in the description of the liquid properties. These results suggest that DeePMD-based DNN potentials are not able to correctly “learn” and, consequently, represent many-body interactions, which implies that DNN potentials may have limited ability to predict the properties for state points that are not explicitly included in the training process. The computational efficiency of the DeePMD framework can still be exploited to train DNN potentials on data-driven many-body potentials, which can thus enable large-scale, “chemically accurate” simulations of various molecular systems, with the caveat that the target state points must have been adequately sampled by the reference data-driven many-body potential in order to guarantee a faithful representation of the associated properties.
Reproductive performance of northern Australian beef herds. 3. Descriptive analysis of major factors affecting reproductive performance
Authors: McCosker K. D. , Smith D. R. , Burns B. M. , Fordyce G. , O’Rourke P. K. , McGowan M. R.
Published: February 2023

Context The performance of commercial beef-breeding herds in northern Australia is highly variable. Identifying and understanding the major factors that influence this is critical in determining which management interventions should be implemented to best manage these factors. Aims This study aimed to describe the occurrence and magnitude of the risk factors identified as being strongly associated with one or more measures of cow performance in northern Australia. Methods A prospective epidemiological study was conducted in a cross-section of commercial beef-breeding herds in northern Australia, to determine and quantify the major associations of up to 83 candidate herd management, nutritional and environmental risk factors with cow performance. Descriptive analyses of significant risk factors were conducted. Key results Unfavourable levels of risk factors were observed for all country types and across three cow-age groups. However, generally, adverse property-level nutritional, environmental and management risk factors had a higher incidence in the Northern Forest, which was associated with significantly lower performance of heifers and cows. This was reflected in generally lower body condition of heifers and cows in this country type. Although the performance of heifers and cows was generally higher in the Southern Forest, the irregular incidence of adverse risk factors contributed to the observed quite variable performance. Conclusions The factors significantly affecting the performance of cows in the major beef-breeding regions of northern Australia are described. These factors were additively more adverse in the Northern Forest. Implications In this study, the necessary understanding of the factors most likely to be affecting the performance beef cows in this environment has been described. This is required to make appropriate decisions about management interventions to control these factors.
Do high recapture rates indicate representative sampling? The relationship between recapture probability, risk-taking, and personality
Authors: Johnstone Kyla Chloe , McArthur Clare , Banks Peter Bruce
Published: February 2023

Context Monitoring programs provide valuable information on wildlife populations, thereby underpinning strategies for conservation and control. For threatened species, where every animal represents a substantial portion of the population, representative sampling is vital. One fundamental challenge during sampling is understanding drivers of survey bias; for instance, behavioural heterogeneity in trap response. Methods such as capture–mark–recapture have long been used to estimate capture and recapture heterogeneity; yet, this method, like many others, is able to gather data only from the trappable and re-trappable portion of the population; a problem that presents a particular challenge for small or vulnerable populations. A greater understanding of why biases arise can result in improved survey methods, more reliable survey data and increased modelling accuracy. Aims We focus on an endangered species with unusually high recapture probabilities (0.78–0.92), namely, the mountain pygmy-possum (Burramys parvus). Specifically, we examine whether, within a single trapping session, a recapture bias exists either as a function of past trapping experience or personality. Methods We tested whether recapture probability differs among cohorts with different capture histories (‘known’ animals captured during trapping sessions in previous years vs ‘new’ animals trapped for the first time in this study). We also tested for individual personality, general risk-taking behaviour during foraging, and subsequent links to recapture probability. Key results Recapture probability was significantly affected by cohort. New animals had lower probabilities of recapture and took fewer risks during foraging than did known animals. Although personality did not significantly influence recapture probability, it did influence risk-taking during foraging. Conclusions Despite high recapture probability within the populations, captures were significantly skewed towards a subset of the population, likely being due to different perceptions of risk among individuals. Implications Understanding potential sources of bias during live-capture surveys is the initial step towards modifying and improving surveys to reduce sampling biases and to ensure representative population sampling.
Persistent binding at dopamine transporters determines sustained psychostimulant effects
Authors: Niello Marco , Sideromenos Spyridon , Gradisch Ralph , O´Shea Ronan , Schwazer Jakob , Maier Julian , Kastner Nina , Sandtner Walter , Jäntsch Kathrin , Lupica Carl R. , Hoffman Alexander F. , Lubec Gert , Loland Claus J. , Stockner Thomas , Pollak Daniela D. , Baumann Michael H. , Sitte Harald H.
Published: February 2023

Psychostimulants interacting with the dopamine transporter (DAT) can be used illicitly or for the treatment of specific neuropsychiatric disorders. However, they can also produce severe and persistent adverse events. Often, their pharmacological properties in vitro do not fully correlate to their pharmacological profile in vivo. Here, we investigated the pharmacological effects of enantiomers of pyrovalerone, α-pyrrolidinovalerophenone, and 3,4-methylenedioxypyrovalerone as compared to the traditional psychostimulants cocaine and methylphenidate, using a variety of in vitro, computational, and in vivo approaches. We found that in vitro drug-binding kinetics at DAT correlate with the time-course of in vivo psychostimulant action in mice. In particular, a slow dissociation (i.e., slowkoff) ofS-enantiomers of pyrovalerone analogs from DAT predicts their more persistent in vivo effects when compared to cocaine and methylphenidate. Overall, our findings highlight the critical importance of drug-binding kinetics at DAT for determining the in vivo profile of effects produced by psychostimulant drugs.
Transcytosis-mediated anterograde transport of TrkA receptors is necessary for sympathetic neuron development and function
Authors: Connor Blaine , Moya-Alvarado Guillermo , Yamashita Naoya , Kuruvilla Rejji
Published: February 2023

In neurons, many membrane proteins, synthesized in cell bodies, must be efficiently delivered to axons to influence neuronal connectivity, synaptic communication, and repair. Previously, we found that axonal targeting of TrkA neurotrophin receptors in sympathetic neurons occurs via an atypical transport mechanism called transcytosis, which relies on TrkA interactions with PTP1B, a protein tyrosine phosphatase. Here, we generated TrkA
R685A
mice, where TrkA receptor signaling is preserved, but its PTP1B-dependent transcytosis is disrupted to show that this mode of axonal transport is essential for sympathetic neuron development and autonomic function
.
TrkA
R685A
mice have decreased axonal TrkA levels in vivo, loss of sympathetic neurons, and reduced innervation of targets. The neuron loss and diminished target innervation phenotypes are specifically restricted to the developmental period when sympathetic neurons are known to rely on the TrkA ligand, nerve growth factor, for trophic support. Postnatal TrkA
R685A
mice exhibit reduced pupil size and eyelid ptosis, indicative of sympathetic dysfunction. Furthermore, we also observed a significant loss of TrkA-expressing nociceptive neurons in the dorsal root ganglia during development in TrkA
R685A
mice, suggesting that transcytosis might be a general mechanism for axonal targeting of TrkA receptors. Together, these findings establish the necessity of transcytosis in supplying TrkA receptors to axons, specifically during development, and highlight the physiological relevance of this axon targeting mechanism in the nervous system.
High-throughput droplet-based analysis of influenza A virus genetic reassortment by single-virus RNA sequencing
Authors: Chen Kuang-Yu , Karuppusamy Jayaprakash , O’Neill Mary B. , Opuu Vaitea , Bahin Mathieu , Foulon Sophie , Ibanez Pablo , Quintana-Murci Lluis , Ozawa Tatsuhiko , van der Werf Sylvie , Nghe Philippe , Naffakh Nadia , Griffiths Andrew , Isel Catherine
Published: February 2023

The segmented RNA genome of influenza A viruses (IAVs) enables viral evolution through genetic reassortment after multiple IAVs coinfect the same cell, leading to viruses harboring combinations of eight genomic segments from distinct parental viruses. Existing data indicate that reassortant genotypes are not equiprobable; however, the low throughput of available virology techniques does not allow quantitative analysis. Here, we have developed a high-throughput single-cell droplet microfluidic system allowing encapsulation of IAV-infected cells, each cell being infected by a single progeny virion resulting from a coinfection process. Customized barcoded primers for targeted viral RNA sequencing enabled the analysis of 18,422 viral genotypes resulting from coinfection with two circulating human H1N1pdm09 and H3N2 IAVs. Results were highly reproducible, confirmed that genetic reassortment is far from random, and allowed accurate quantification of reassortants including rare events. In total, 159 out of the 254 possible reassortant genotypes were observed but with widely varied prevalence (from 0.038 to 8.45%). In cells where eight segments were detected, all 112 possible pairwise combinations of segments were observed. The inclusion of data from single cells where less than eight segments were detected allowed analysis of pairwise cosegregation between segments with very high confidence. Direct coupling analysis accurately predicted the fraction of pairwise segments and full genotypes. Overall, our results indicate that a large proportion of reassortant genotypes can emerge upon coinfection and be detected over a wide range of frequencies, highlighting the power of our tool for systematic and exhaustive monitoring of the reassortment potential of IAVs.
Resurrection genomics provides molecular and phenotypic evidence of rapid adaptation to salinization in a keystone aquatic species
Authors: Wersebe Matthew J. , Weider Lawrence J.
Published: February 2023

Ecologists and evolutionary biologists are increasingly cognizant of rapid adaptation in wild populations. Rapid adaptation to anthropogenic environmental change is critical for maintaining biodiversity and ecosystems services into the future. Anthropogenic salinization of freshwater ecosystems is quickly emerging as a primary threat, which is well documented in the northern temperate ecoregion. Specifically, many northern temperate lakes have undergone extensive salinization because of urbanization and the associated increase in impervious surfaces causing runoff, and the extensive use of road deicing salts (e.g., NaCl). It remains unclear whether increasing salinization will lead to extirpation of species from these systems. Using a “resurrection genomics” approach, we investigated whether the keystone aquatic herbivore,
Daphnia pulicaria,
has evolved increased salinity tolerance in a severely salinized lake located in Minnesota, USA. Whole-genome resequencing of 54
Daphnia
clones from the lake and hatched from resting eggs that represent a 25-y temporal contrast demonstrates that many regions of the genome containing genes related to osmoregulation are under selection in the study population. Tolerance assays of clones revealed that the most recent clones are more tolerant to salinity than older clones; this pattern is concomitant with the temporal pattern of stabilizing salinity in this lake. Together, our results demonstrate that keystone species such as
Daphnia
can rapidly adapt to increasing freshwater salinization. Further, our results indicate that rapid adaptation to salinity may allow lake
Daphnia
populations to persist in the face of anthropogenic salinization maintaining the food webs and ecosystem services they support despite global environmental change.
Using cognitive psychology to understand GPT-3
Authors: Binz Marcel , Schulz Eric
Published: February 2023

We study GPT-3, a recent large language model, using tools from cognitive psychology. More specifically, we assess GPT-3’s decision-making, information search, deliberation, and causal reasoning abilities on a battery of canonical experiments from the literature. We find that much of GPT-3’s behavior is impressive: It solves vignette-based tasks similarly or better than human subjects, is able to make decent decisions from descriptions, outperforms humans in a multiarmed bandit task, and shows signatures of model-based reinforcement learning. Yet, we also find that small perturbations to vignette-based tasks can lead GPT-3 vastly astray, that it shows no signatures of directed exploration, and that it fails miserably in a causal reasoning task. Taken together, these results enrich our understanding of current large language models and pave the way for future investigations using tools from cognitive psychology to study increasingly capable and opaque artificial agents.
Definition of the contribution of an Osteopontin-producing CD11c
+
microglial subset to Alzheimer’s disease
Authors: Qiu Yiguo , Shen Xianli , Ravid Orly , Atrakchi Dana , Rand Daniel , Wight Andrew E. , Kim Hye-Jung , Liraz-Zaltsman Sigal , Cooper Itzik , Schnaider Beeri Michal , Cantor Harvey
Published: February 2023

Alzheimer’s disease (AD) is the most common form of incurable dementia and represents a critical public health issue as the world’s population ages. Although microglial dysregulation is a cardinal feature of AD, the extensive heterogeneity of these immunological cells in the brain has impeded our understanding of their contribution to this disease. Here, we identify a pathogenic microglial subset which expresses the CD11c surface marker as the sole producer of Osteopontin (OPN) in the 5XFAD mouse model of AD. OPN production divides Disease-Associated Microglia (DAM) into two functionally distinct subsets, i.e., a protective CD11c
+
OPN
−
subset that robustly ingests amyloid β (Aβ) in a noninflammatory fashion and a pathogenic CD11c
+
OPN
+
subset that produces proinflammatory cytokines and fails to ingest significant amounts of Aβ. Genetic ablation of OPN or administration of monoclonal anti-OPN antibody to 5XFAD mice reduces proinflammatory microglia, plaque formation, and numbers of dystrophic neurites and results in improved cognitive function. Analysis of brain tissue from AD patients indicates that levels of OPN-producing CD11c
+
microglia correlate strongly with the degree of cognitive deficit and AD neuropathology. These findings define an OPN-dependent pathway to disease driven by a distinct microglial subset, and identify OPN as a novel therapeutic target for potentially effective immunotherapy to treat AD.
The SspB adaptor drives structural changes in the AAA+ ClpXP protease during ssrA-tagged substrate delivery
Authors: Ghanbarpour Alireza , Fei Xue , Baker Tania A. , Davis Joseph H. , Sauer Robert T.
Published: February 2023

Energy-dependent protein degradation by the AAA+ ClpXP protease helps maintain protein homeostasis in bacteria and eukaryotic organelles of bacterial origin. In 
Escherichia coli
and many other proteobacteria, the SspB adaptor assists ClpXP in degrading ssrA-tagged polypeptides produced as a consequence of tmRNA-mediated ribosome rescue. By tethering these incomplete ssrA-tagged proteins to ClpXP, SspB facilitates their efficient degradation at low substrate concentrations. How this process occurs structurally is unknown. Here, we present a cryo-EM structure of the SspB adaptor bound to a GFP-ssrA substrate and to ClpXP. This structure provides evidence for simultaneous contacts of SspB and ClpX with the ssrA tag within the tethering complex, allowing direct substrate handoff concomitant with the initiation of substrate translocation. Furthermore, our structure reveals that binding of the substrate·adaptor complex induces unexpected conformational changes within the spiral structure of the AAA+ ClpX hexamer and its interaction with the ClpP tetradecamer.
Understanding language shift
Authors: Grenoble Lenore A , Osipov Boris
Published: February 2023

This is a response to the commentaries on our epistemological paper, The dynamics of bilingualism in language
shift ecologies. The commentaries highlight the challenges in studying language shift ecologies and the competing goals of
different research approaches. We hope this set of papers invokes rich discussion about other possible research questions we can
ask and the research methodologies we can use to answer them.
L2 English learners’ verb lexicalization of motion events
Authors: Jeon Jeeyoung , Sung Min-Chang
Published: February 2023

This study examines the effects of L2 proficiency and manner salience on English learners’ verb lexicalization of spontaneous motion events. Three proficiency groups of L1 Korean learners of L2 English were asked to describe spontaneous motion situations, and their use of verbs was compared to that of native English speakers. Results indicate that L2 learners’ verb lexicalization was heavily influenced by the typological patterns of their native language, but the development of target-like lexicalization patterns occurred even though it plateaued at a certain acquisitional phase. Moreover, it was found that the degree of adopting target-like lexicalization patterns varied by manner-of-motion types (i.e., high-salience manner such asswimversus low-salience manner such aswalk) in all three learner groups, implying that the inherent salience of manner has an impact on L2 lexicalization of spontaneous motion.
Analysis of decarburisation mechanism of Fe-C alloy strip
Authors: Zhou Meijie , Ai Liqun , Hong Lukuo , Hou Yaobin , Sun Caijiao
Published: February 2023

Comparative experiments on different decarburisation processes of Fe-C alloys in Ar-CO-CO2 and Ar-H2O-H2 atmospheres were carried out. The fundamental principles of carbon distribution, migration, and conversion are elucidated during decarburisation in both atmospheres. The completely decarburised layer of 2-mm-thick strip in Ar-CO-CO2 atmosphere appeared about 20 min later than the decarburisation in Ar-H2O-H2 atmosphere. Compared with the decarburisation in the Ar-H2O-H2 atmosphere, the carbon-rich phase dissolution zone is wider and the solid solution carbon content in the centre side is lower in the Ar-CO-CO2 atmosphere. The concentration gradient of solid solution carbon on the centre side of the interface of austenite zone in Ar-CO-CO2 atmosphere is smaller than that in the Ar-H2O-H2 atmosphere.
Stopping the fat: Repurposing an antidepressant for cancer treatment
Authors: Bhullar Deepika , Commisso Cosimo
Published: February 2023

In this issue of JEM, Chu and An et al. (2022. J. Exp. Med.https://doi.org/10.1084/jem.20221316) describe the role of the tricyclic antidepressant nortriptyline in inhibition of fatty acid uptake. Nortriptyline promotes cell acidification and suppresses macropinocytosis, providing a link between fatty acid uptake and tumor progression.
General spherical harmonic bra-ket overlap integrals of trigonometric functions
Authors: Lingetti Giuseppe , Pani Paolo
Published: February 2023

Closed formulas in terms of double sums of Clebsch–Gordan coefficients are computed for the evaluation of bra-ket spherical harmonic overlap integrals of a wide class of trigonometric functions. These analytical expressions can find useful application in problems involving non-separable wave equations, e.g. general-relativistic perturbation theory, electromagnetism, quantum theory, etc, wherein the overlap integrals arise from the coupling among different angular modes. We provide some examples related to linear perturbations of spinning black holes in general relativity and modified gravity, in which the analytical formulas for the overlap integrals are particularly useful to compute the black-hole spectrum.
A linear response relation for perturbed Einstein’s equations with a Langevin source: applications to perturbations in compact stars
Authors: Satin Seema
Published: February 2023

A new linear response relation for the perturbed Einstein’s equation is introduced. We give the idea of considering the metric perturbations as a linear response to the fluid (matter) perturbations in strong gravity regions. This can be meaningful when the perturbations in the system are driven by sources internal to the fluid (matter) in the relativistic star. The aim is to study the strong regions embedding the compact matter like that of the internal structure of relativistic stars, with this new framework. The formulations are specifically done to address the generalized stochastic perturbations which can arise in the dense matter at intermediate scales. These internally sourced perturbations lead to the possibility of equilibrium and non-equilibrium (dynamical or thermal) statistical analysis for the properties of compact matter at the sub-hydro mesoscopic scales, which are yet unexplored. A general relativistic Langevin formalism, defining a random driving source and its analytical solutions for a simple example are given. With a first principles approach, this new framework and its potential towards building up a theme of research in asteroseismology is discussed.
CTTK: a new method to solve the initial data constraints in numerical relativity
Authors: Aurrekoetxea Josu C , Clough Katy , Lim Eugene A
Published: February 2023

In numerical relativity simulations with non-trivial matter configurations, one must solve the Hamiltonian and momentum constraints of the ADM formulation for the metric variables in the initial data. We introduce a new scheme based on the standard conformal transverse-traceless decomposition, in which instead of solving the Hamiltonian constraint as a 2nd order elliptic equation for a choice of mean curvature K, we solve an algebraic equation for K for a choice of conformal factor. By doing so, we evade the existence and uniqueness problem of solutions of the Hamiltonian constraint without using the usual conformal rescaling of the source terms. This is particularly important when the sources are fundamental fields, as reconstructing the fields’ configurations from the rescaled quantities is potentially problematic. Using an iterative multigrid solver, we show that this method provides rapid convergent solutions for several initial conditions that have not yet been studied in numerical relativity; namely (a) periodic inhomogeneous spacetimes with large random Gaussian scalar field perturbations and (b) asymptotically flat black hole spacetimes with rotating scalar clouds.
Pole inflation and primordial black holes formation in Starobinsky-like supergravity
Authors: Aoki Shuntaro , Ishikawa Ryotaro , Ketov Sergei V
Published: February 2023

We extend the Cecotti–Kallosh model of Starobinsky inflation in supergravity by adding a holomorphic function to the superpotential in order to generate a large peak in the power spectrum of scalar (curvature) perturbations. In our approach, the singular non-canonical kinetic terms are largely responsible for inflation (as an attractor solution), whereas the superpotential is engineered to generate a production of PBH. We study the cases with (a) a linear holomorphic function, (b) a quadratic holomorphic function, and (c) an exponential holomorphic function, as regards the dependence of inflation and PBH production upon parameters of those functions and initial conditions, as well as verify viability of inflation with our superpotentials. We find that an efficient production of PBH consistent with cosmic microwave background measurements is only possible in the second (b) case. We calculate the masses of the produced PBH and find that they are below the Hawking (black hole) evaporation limit, so that they cannot be part of the current dark matter in our Universe.
New perspectives in time-resolved laser-induced electron diffraction
Authors: De Giovannini Umberto , Küpper Jochen , Trabattoni Andrea
Published: February 2023

Imaging the microscopic world in real space and real time is a grand challenge of science. In the landscape of time-resolved imaging techniques, laser-induced electron diffraction (LIED) has recently shown to be a promising candidate to push the frontiers of ultrafast molecular imaging. In this work, we review the main achievements of LIED research in terms of experimental results and advanced modelling. We also envision interesting perspectives toward the future advancement of time-resolved LIED imaging.
Reduced TiO2 with prolonged electron lifetime for improving photocatalytic water reduction activity
Authors: Sudrajat Hanggara , Susanti Ari , Hartuti Sri
Published: February 2023

The reduction of anatase TiO2 with NaBH4 under argon atmosphere at a high temperature resulted in a longer electron lifetime and a larger electron population. The reduced gray anatase sample with disorder layer showed a higher evolution rate of H2 (130.2 μmol h−1 g−1) compared to pristine TiO2 (24.1 μmol h−1 g−1) in the presence of Pt co-catalyst in an aqueous glucose solution under exposure to ultraviolet light (λ ⩽ 400 nm). Ti3+ and oxygen vacancy defects were proposed to exist in the reduced TiO2. A continuum tail forms above the valence band edge top as a result of these two defects, which contribute to the lattice disorder. This is presumably also the case with the conduction band, which has a continuum tail composed of mid-gap states as a result of the defects. The Ti3+ and oxygen vacancy defects operate as shallow traps for photoexcited electrons, thereby preventing recombination. Since the defects are primarily located at the surface, i.e. in the disorder layer, the photoexcited electrons in shallow traps hence become readily available for the reduction of H3O+ into H2. The prolonged electron lifetime increases the photoexcited electron population in the reduced TiO2, resulting in enhanced water reduction activity.
Bulk-surface coupling in dual topological insulator Bi1Te1 and Sb-doped Bi1Te1 single crystals via electron-phonon interaction
Authors: Mandal Shoubhik , Mallick Debarghya , Bitla Yugandhar , Ganesan R , Kumar P S Anil
Published: February 2023

Recently,

B
i

1

T
e

1

has been proved to be a dual topological insulator (TI), a new subclass of symmetry-protected topological phases, and predicted to be higher order topological insulator (HOTI). Being a dual TI (DTI), Bi1Te1 is said to host quasi-1D surface states (SSs) due to weak TI phase and topological crystalline insulating SSs at the same time. On the other hand, HOTI supports topologically protected hinge states. So,

B
i

1

T
e

1

is a unique platform to study the electrical signature of topological SS (TSS) of fundamentally different origins. Though there is a report of magneto-transport measurements on large-scale Bi1Te1 thin films, the Bi1Te1 single crystal is not studied experimentally to date. Even the doping effect in a DTI Bi1Te1 is missing in the literature. In this regard, we performed the perpendicular and parallel field magneto-transport measurement on the exfoliated microflake of Bi1Te1 and Sb-doped Bi1Te1 single crystals, grown by the modified Bridgmann method. Our metallic sample shows the weak anti-localization behavior analyzed by the multi-channel Hikami-Larkin-Nagaoka equation. We observed the presence of a pair of decoupled TSS. Further, we extracted the dephasing index (β) from temperature (T)-dependence of phase coherence length (L

ϕ

), following the power law equation (L

ϕ

∝

T

−
β

). The thickness-dependent value of β indicates the transition in the dephasing mechanism from electron-electron to electron-phonon interaction with the increase in thickness, indicating the enhancement in the strength of bulk-surface coupling. Sb-doped system shows weakened bulk-surface coupling, hinted by the reduced dephasing indices.