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Structural softness - often characterized by unstable phonon modes and large electromechanical responses - is a hallmark of ferroelectric perovskites like BaTiO3 or Pb(Ti,Zr)O3. Whether HfO2 ferroelectrics present any such structural softness is still a matter of debate. Here, using first principles calculations, we predict that it is possible to induce structural instabilities in hafnia. More specifically, our calculations show that in-plane epitaxial tensile strain causes a mechanical instability of the ferroelectric phase, which transforms discontinuously into an antipolar polymorph. Then, upon release of the tensile strain, the antipolar polymorph transforms back to the ferroelectric state by a soft phonon instability. We show that the softening is accompanied by enhancements in the dielectric and piezoelectric responses. While these transitions occur at high epitaxial strains for pure ferroelectric HfO2, we show that the required deformations are considerably lowered in superlattices with other simple oxides, which may facilitate realizing these effects experimentally., Comment: 15 pages including supplementary information

Photonic bound states in the continuum (BICs) have emerged as a versatile tool for enhancing light-matter interactions by strongly confining light fields. Chiral BICs are photonic resonances with a high degree of circular polarisation, which hold great promise for spin-selective applications in quantum optics and nanophotonics. Here, we demonstrate a novel application of a chiral BIC for inducing strong coupling between the circularly polarised photons and spin-polarised (valley) excitons (bound electron-hole pairs) in atomically-thin transition metal dichalcogenide crystals (TMDCs). By placing monolayer WS$_2$ onto the BIC-hosting metasurface, we observe the formation of intrinsically chiral, valley-selective exciton polaritons, evidenced by circularly polarised photoluminescence (PL) at two distinct energy levels. The PL intensity and degree of circular polarisation of polaritons exceed those of uncoupled excitons in our structure by an order of magnitude. Our microscopic model shows that this enhancement is due to folding of the Brillouin zone creating a direct emission path for high-momenta polaritonic states far outside the light cone, thereby providing a shortcut to thermalisation (energy relaxation) and suppressing depolarisation. Moreover, while the polarisation of the upper polariton is determined by the valley excitons, the lower polariton behaves like an intrinsic chiral emitter with its polarisation fixed by the BIC. Therefore, the spin alignment of the upper and lower polaritons ($\uparrow\downarrow$ and $\uparrow \uparrow$) can be controlled by $\sigma^+$ and $\sigma^-$ polarised optical excitation, respectively. Our work introduces a new type of chiral light-matter quasi-particles in atomically-thin semiconductors and provides an insight into their energy relaxation dynamics.

Training and deploying machine learning models relies on a large amount of human-annotated data. As human labeling becomes increasingly expensive and time-consuming, recent research has developed multiple strategies to speed up annotation and reduce costs and human workload: generating synthetic training data, active learning, and hybrid labeling. This tutorial is oriented toward practical applications: we will present the basics of each strategy, highlight their benefits and limitations, and discuss in detail real-life case studies. Additionally, we will walk through best practices for managing human annotators and controlling the quality of the final dataset. The tutorial includes a hands-on workshop, where attendees will be guided in implementing a hybrid annotation setup. This tutorial is designed for NLP practitioners from both research and industry backgrounds who are involved in or interested in optimizing data labeling projects., Comment: To be presented at COLING 2025

The magnetised near detector (ND280) of the T2K long-baseline neutrino oscillation experiment has been recently upgraded aiming to satisfy the requirement of reducing the systematic uncertainty from measuring the neutrinonucleus interaction cross section, which is the largest systematic uncertainty in the search for leptonic charge-parity symmetry violation. A key component of the upgrade is SuperFGD, a 3D segmented plastic scintillator detector made of approximately 2,000,000 optically-isolated 1 cm3 cubes. It will provide a 3D image of GeV neutrino interactions by combining tracking and stopping power measurements of final state particles with sub-nanosecond time resolution. The performance of SuperFGD is characterized by the precision of its response to charged particles as well as the systematic effects that might affect the physics measurements. Hence, a detailed Geant4 based optical simulation of the SuperFGD building block, i.e. a plastic scintillating cube read out by three wavelength shifting fibers, has been developed and validated with the different datasets collected in various beam tests. In this manuscript the description of the optical model as well as the comparison with data are reported., Comment: 31 pages, 15 figures

Novel CaV1-xWxO3 (0.1 < x < 0.33) oxides with an orthorhombically distorted perovskite structure of GdFeO3 type have been synthesized. These compounds contain in B-position W+6 and V cations in an oxidation state between +4 (CaVO3) and +3 (x=0.33). CaV0.9W0.1O3 compound possesses metallic type of conductivity and Pauli paramagnetism. The intermediate compositions are between bad metal and semiconducting type of behavior with paramagnetic response. CaV0.67W0.33O3 is a Mott insulator with localized V+3 moments coupled by strong antiferromagnetic interactions. It demonstrates the reduction of effective magnetic moment at high temperatures and canonical spin glass state formation with the freezing temperature Tg = 27.5 K seen in dc - and ac - magnetic susceptibility. Disorder in the magnetic subsystem induces a broad peak in magnetic contribution of the heat capacity at Tmax = 46 K., Comment: 13 pages, 6 figures

Ferroelectrics under suitable electric boundary conditions can present a negative capacitance response, whereby the total voltage drop across the ferroelectric opposes the externally applied bias. When the ferroelectric is in a heterostructure, this behavior yields a voltage amplification in the other elements, an effect that could be leveraged in low-power electronic devices. Interestingly, the mentioned voltage amplification should have an accompanying elastic effect. Specifically, in the typical case that the materials in contact with the ferroelectric are non-polar dielectrics, those should present an enhanced electrostrictive response. Here we use atomistic simulations - of model PbTiO$_{3}$/SrTiO$_{3}$ ferroelectric/dielectric superlattices displaying negative capacitance - to show that this is indeed the case: we reveal the enhanced elastic response of the dielectric layer and show that it is clearly linked to the voltage amplification. We argue that this "elastic amplification" could serve as a convenient experimental fingerprint for negative capacitance. Further, we propose that it may have interest on its own, e.g. for the development of low-power electromechanical actuators.

This paper describes the organization and findings of AXOLOTL'24, the first multilingual explainable semantic change modeling shared task. We present new sense-annotated diachronic semantic change datasets for Finnish and Russian which were employed in the shared task, along with a surprise test-only German dataset borrowed from an existing source. The setup of AXOLOTL'24 is new to the semantic change modeling field, and involves subtasks of identifying unknown (novel) senses and providing dictionary-like definitions to these senses. The methods of the winning teams are described and compared, thus paving a path towards explainability in computational approaches to historical change of meaning., Comment: Proceedings of the 5th Workshop on Computational Approaches to Historical Language Change (ACL'24)

The paraphrase identification task involves measuring semantic similarity between two short sentences. It is a tricky task, and multilingual paraphrase identification is even more challenging. In this work, we train a bi-encoder model in a contrastive manner to detect hard paraphrases across multiple languages. This approach allows us to use model-produced embeddings for various tasks, such as semantic search. We evaluate our model on downstream tasks and also assess embedding space quality. Our performance is comparable to state-of-the-art cross-encoders, with only a minimal relative drop of 7-10% on the chosen dataset, while keeping decent quality of embeddings.

We use contextualized word definitions generated by large language models as semantic representations in the task of diachronic lexical semantic change detection (LSCD). In short, generated definitions are used as `senses', and the change score of a target word is retrieved by comparing their distributions in two time periods under comparison. On the material of five datasets and three languages, we show that generated definitions are indeed specific and general enough to convey a signal sufficient to rank sets of words by the degree of their semantic change over time. Our approach is on par with or outperforms prior non-supervised sense-based LSCD methods. At the same time, it preserves interpretability and allows to inspect the reasons behind a specific shift in terms of discrete definitions-as-senses. This is another step in the direction of explainable semantic change modeling., Comment: Findings of ACL 2024

The properties of functional oxide heterostructures are strongly influenced by the physics governing their interfaces. Modern deposition techniques allow us to accurately engineer the interface physics through the growth of atomically precise heterostructures. This enables minute control over the electronic, magnetic, and structural characteristics. Here, we investigate the magnetic properties of tailor-made superlattices employing the ferromagnetic and insulating double perovskites RE$_2$NiMnO$_6$ (RE = La, Nd), featuring distinct Curie temperatures. Adjusting the superlattice periodicity at the unit cell level allows us to engineer their magnetic phase diagram. Large periodicity superlattices conserve the individual para- to ferromagnetic transitions of the La$_2$NiMnO$_6$ and Nd$_2$NiMnO$_6$ parent compounds. As the superlattice periodicity is reduced, the Curie temperatures of the superlattice constituents converge and, finally, collapse into one single transition for the lowest period samples. This is a consequence of the magnetic order parameter propagating across the superlattice interfaces, as supported by a minimal Landau theory model. Further, we find that the Nd-Ni/Mn exchange interaction can be enhanced by the superlattice interfaces. This leads to a field-induced reversal of the Nd magnetic moments, as confirmed by synchrotron X-ray magnetic circular dichroism measurements and supported by first-principles calculations. Our work demonstrates how superlattice engineering can be employed to fine-tune the magnetic properties in oxide heterostructures and broadens our understanding of magnetic interfacial effects.

Mesospheric CO2 clouds are one of two types of carbon dioxide clouds known on Mars. We present observations of mesospheric CO2 clouds made by Atmospheric Chemistry Suit (ACS) onboard the ESA-Roscosmos ExoMars Trace Gas Orbiter (TGO). We analyzed 1663 solar occultation sessions of Thermal InfraRed (TIRVIM) and Middle InfraRed (MIR) channels of ACS covering more than two Martian years that contain spectra of 2.7 {\mu}m carbon dioxide ice absorption band. That allowed us to unambiguously discriminate carbon dioxide ice aerosols from mineral dust and water ice aerosols, not relying on the information of atmospheric thermal conditions. CO2 clouds were detected in eleven solar occultation observations at altitudes from 39 km to 90 km. In five cases, there were two or three layers of CO2 clouds that were vertically separated by 5-15 km gaps. Effective radius of CO2 aerosol particles is in the range of 0.1-2.2 {\mu}m. Spectra produced by the smallest particles indicate a need for a better resolved CO2 ice refractive index. Nadir optical depth of CO2 clouds is in the range 5*10^{-4}-4*10^{-2} at both 2.7 {\mu}m and 0.8 {\mu}m. Asymmetrical diurnal distribution of detections observed by ACS is potentially due to local time variations of temperature induced by thermal tides. Two out of five cases of carbon dioxide cloud detections made by the TIRVIM instrument reveal the simultaneous presence of CO2 ice and H2O ice aerosols. Temperature profiles measured by the Near InfraRed (NIR) channel of ACS are used to calculate CO2 saturation ratio S at locations of carbon dioxide clouds. Supersaturation S > 1 is detected in only 5 out of 19 cases of CO2 cloud layers; extremely low values of S < 0.1 are found in 9 out of 19 cases., Comment: 29 pages, 10 figures. Submitted to Icarus

Using a large sample of fast radio bursts (FRBs) from the first CHIME/FRB catalog, we apply the Lynden-Bell's c$^-$ method to study their energy function and formation rate evolutions with redshift. It is found with the non-parametric Kendell's $\tau$ statistics that the FRB energy strongly evolves with the cosmological redshift as $E(z)\propto(1 + z)^{5.23}$. After removing the redshift dependence, the local energy distribution can be described by a broken power-law form of $\Psi(E_{0})\propto E_{0}^{-0.38}$ for the low-energy segment and $\Psi(E_{0})\propto E_{0}^{-2.01}$ for the high-energy segment with a dividing line of $\sim2.1\times10^{40} \rm erg$. Interestingly, we find that the formation rate of CHIME FRBs also evolves with redshift as $\rho(z)\propto(1+z)^{-4.73\pm0.08}$. The local formation rate $\rho(0)$ of the CHIME FRBs is constrained to be about $ 1.25\times 10^4\rm{\,Gpc^{-3}yr^{-1}}$ that is comparable with some previous estimations. In addition, we notice the formation rate not only exceeds the star formation rate at the lower redshifts but also always declines with the increase of redshift, which does not match the star formation history at all. Consequently, we suggest that most FRBs could originate from the older stellar populations.

The Super-Kamiokande and T2K collaborations present a joint measurement of neutrino oscillation parameters from their atmospheric and beam neutrino data. It uses a common interaction model for events overlapping in neutrino energy and correlated detector systematic uncertainties between the two datasets, which are found to be compatible. Using 3244.4 days of atmospheric data and a beam exposure of $19.7(16.3) \times 10^{20}$ protons on target in (anti)neutrino mode, the analysis finds a 1.9$\sigma$ exclusion of CP-conservation (defined as $J_{CP}=0$) and a preference for the normal mass ordering., Comment: 12 pages, 4 figures

Retrieving the optical depth of the Martian clouds ($\tau_\mathrm{cld}$) is a powerful way to monitor their spatial and temporal evolution. However, such retrievals from nadir imagery rely on several assumptions, including the vertical structure of the clouds in the atmosphere. Here we compare the results of cloud optical depth retrievals at 320 nm from the Emirates eXploration Imager (EXI) onboard the Emirates Mars Mission (EMM) "Hope" orbiter performed using a basic uniform cloud profile used in previous studies and using derived cloud profiles obtained from near-simultaneous Solar Occultation observations in the 3.1-3.4 $\mu$m spectral range from the Middle-Infrared channel of the Atmospheric Chemistry Suite (ACS) instrument onboard the ESA Trace Gas Orbiter (TGO). We show that the latitudinal dependence of the cloud vertical profiles can have a strong impact on the nadir retrievals; neglecting it can lead to a significant underestimation of $\tau_\mathrm{cld}$ in the polar regions (up to 25 % to 50 %, depending on the vertical distribution of the dust in the atmosphere) and to a lesser extent, to an overestimation of $\tau_\mathrm{cld}$ around the equator. We also discuss the impact of a vertically-dependent particle size profile, as previous studies have shown the presence of very small water ice particles at the top of the clouds. From this analysis, we provide recommendations for the improvement of water ice cloud parameterization in radiative transfer algorithms in nadir atmospheric retrievals.

Genomic data has become increasingly accessible to the general public with the advent of companies offering whole genome sequencing at a relatively low cost. However, their reports are not verifiable due to a lack of crucial details and transparency: polygenic risk scores do not always mention all the polymorphisms involved. Simultaneously, tackling the manual investigation and interpretation of data proves challenging for individuals lacking a background in genetics. Currently, there is no open-source or commercial solution that provides comprehensive longevity reports surpassing a limited number of polymorphisms. Additionally, there are no ready-made, out-of-the-box solutions available that require minimal expertise to generate reports independently. To address these issues, we have developed the Just-DNA-Seq open-source genomic platform. Just-DNA-Seq aims to provide a user-friendly solution to genome annotation by allowing users to upload their own VCF files and receive annotations of their genetic variants and polygenic risk scores related to longevity. We also created GeneticsGenie custom GPT that can answer genetics questions based on our modules. With the Just-DNA-Seq platform, we want to provide full information regarding the genetics of long life: disease-predisposing variants, that can reduce lifespan and manifest at different age (cardiovascular, oncological, neurodegenerative diseases, etc.), pro-longevity variants and longevity drug pharmacokinetics. In this research article, we will discuss the features and capabilities of Just-DNA-Seq, and how it can benefit individuals looking to understand and improve their health. It's crucial to note that the Just-DNA-Seq platform is exclusively intended for scientific and informational purposes and is not suitable for medical applications., Comment: 41 pages, 7 figures

We present a dataset of word usage graphs (WUGs), where the existing WUGs for multiple languages are enriched with cluster labels functioning as sense definitions. They are generated from scratch by fine-tuned encoder-decoder language models. The conducted human evaluation has shown that these definitions match the existing clusters in WUGs better than the definitions chosen from WordNet by two baseline systems. At the same time, the method is straightforward to use and easy to extend to new languages. The resulting enriched datasets can be extremely helpful for moving on to explainable semantic change modeling., Comment: LREC-COLING 2024

Monochromatic gamma-ray signals constitute a potential smoking gun signature for annihilating or decaying dark matter particles that could relatively easily be distinguished from astrophysical or instrumental backgrounds. We provide an updated assessment of the sensitivity of the Cherenkov Telescope Array (CTA) to such signals, based on observations of the Galactic centre region as well as of selected dwarf spheroidal galaxies. We find that current limits and detection prospects for dark matter masses above 300 GeV will be significantly improved, by up to an order of magnitude in the multi-TeV range. This demonstrates that CTA will set a new standard for gamma-ray astronomy also in this respect, as the world's largest and most sensitive high-energy gamma-ray observatory, in particular due to its exquisite energy resolution at TeV energies and the adopted observational strategy focussing on regions with large dark matter densities. Throughout our analysis, we use up-to-date instrument response functions, and we thoroughly model the effect of instrumental systematic uncertainties in our statistical treatment. We further present results for other potential signatures with sharp spectral features, e.g.~box-shaped spectra, that would likewise very clearly point to a particle dark matter origin., Comment: 44 pages JCAP style (excluding author list and references), 19 figures; minor changes to match published version