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As part of the Young Exoplanets Spectroscopic Survey (YESS), this study explores the spot variability of 13 T Tauri Stars (TTSs) in the near-infrared $H$ band, using spectra from the Immersion GRating INfrared Spectrometer (IGRINS). By analyzing effective temperature ($T_{\rm eff}$) sensitive lines of atomic FeI at ~1.56259 um and ~1.56362 um, and molecular OH at ~1.56310 um and ~1.56317 um, we develop an empirical equivalent width ratio (EWR) relationship for $T_{\rm eff}$ in the range of 3400-5000 K. This relationship allows for precise relative $T_{\rm eff}$ estimates to within tens of Kelvin and demonstrates compatibility with solar metallicity target models. However, discrepancies between observational data and model predictions limit the extension of the $T_{\rm eff}$-EWR relationship to a broader parameter space. Our study reveals that both classical and weak-line TTSs can exhibit $T_{\rm eff}$ variations exceeding 150 K over a span of two years. The detection of a quarter-phase delay between the EWR and radial velocity phase curves in TTSs indicates spot-driven signals. A phase delay of 0.06 $\pm$ 0.13 for CI Tau, however, suggests additional dynamics, potentially caused by planetary interaction, inferred from a posited 1:1 commensurability between the rotation period and orbital period. Moreover, a positive correlation between $T_{\rm eff}$ variation amplitude and stellar inclination angle support the existence of high-latitude spots on TTSs, further enriching our understanding of stellar surface activity in young stars., Comment: 31 pages, 19 figures, and 5 tables. Accepted to ApJ

The excited states of unstable $^{20}$O were investigated via $\gamma$-ray spectroscopy following the $^{19}$O$(d,p)^{20}$O reaction at 8 $A$MeV. By exploiting the Doppler Shift Attenuation Method, the lifetime of the 2$^+_2$ and 3$^+_1$ states were firmly established. From the $\gamma$-ray branching and E2/M1 mixing ratios for transitions deexciting the 2$^+_2$ and 3$^+_1$ states, the B(E2) and B(M1) were determined. Various chiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states, along with a standard USDB interaction, were compared with the experimentally obtained data. Such a comparison for a large set of $\gamma$-ray transition probabilities with the valence space in medium similarity renormalization group ab-initio calculations was performed for the first time in a nucleus far from stability. It was shown that the ab-initio approaches using chiral EFT forces are challenged by detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilities were found to be a very constraining test of the performance of the ab-initio models., Comment: Supplemental Material available

We propose an unfolded accelerated projected-gradient descent procedure to estimate model and algorithmic parameters for image super-resolution and molecule localization problems in image microscopy. The variational lower-level constraint enforces sparsity of the solution and encodes different noise statistics (Gaussian, Poisson), while the upper-level cost assesses optimality w.r.t.~the task considered. In more detail, a standard $\ell_2$ cost is considered for image reconstruction (e.g., deconvolution/super-resolution, semi-blind deconvolution) problems, while a smoothed $\ell_1$ is employed to assess localization precision in some exemplary fluorescence microscopy problems exploiting single-molecule activation. Several numerical experiments are reported to validate the proposed approach on synthetic and realistic ISBI data.

Close binary systems present challenges to planet formation. As binary separations decrease, so too do the occurrence rates of protoplanetary disks in young systems and planets in mature systems. For systems that do retain disks, their disk masses and sizes are altered by the presence of the binary companion. Through the study of protoplanetary disks in binary systems with known orbital parameters, we seek to determine the properties that promote disk retention and, therefore, planet formation. In this work, we characterize the young binary-disk system, FO Tau. We determine the first full orbital solution for the system, finding masses of $0.35^{+0.06}_{-0.05}\ M_\odot$ and $0.34\pm0.05\ M_\odot$ for the stellar components, a semi-major axis of $22(^{+2}_{-1})$ AU, and an eccentricity of $0.21(^{+0.04}_{-0.03})$. With long-baseline ALMA interferometry, we detect 1.3mm continuum and $^{12}{\mathrm{CO}} \ (J=2-1)$ line emission toward each of the binary components; no circumbinary emission is detected. The protoplanetary disks are compact, consistent with being truncated by the binary orbit. The dust disks are unresolved in the image plane and the more extended gas disks are only marginally resolved. Fitting the continuum and CO visibilities, we determine the inclination of each disk, finding evidence for alignment of the disk and binary orbital planes. This study is the first of its kind linking the properties of circumstellar protoplanetary disks to a precisely known binary orbit. In the case of FO Tau, we find a dynamically placid environment (coplanar, low eccentricity), which may foster its potential for planet formation., Comment: AJ accepted, 29 pages, 14 figures

Using the 3D smoothed particle hydrodynamics code PHANTOM, we investigate the evolution of the orbital properties of massive black hole binaries embedded in massive discs where gravitational instabilities (GIs) triggered by the disc self-gravity are the only source of angular momentum transport. In particular, we investigate the evolution of binaries with different initial eccentricities $e_0=0.05,\,0.5,\,0.8$ and mass ratios $q=0.1,\,0.3,\,0.9$. Our simulations suggest that there might not be a unique value of critical eccentricity. We find initially more eccentric binaries to tend to higher asymptotic eccentricity values than more circular ones. This implies that there is a range of critical eccentricity values, that depends on the initial condition of the system. In particular, we find the width of this range to be narrower for more unequal binaries. We furthermore measure preferential accretion onto our binaries, finding more accretion onto the primary only for mass ratio $q=0.3$ and eccentricity $e=0.8$. We discuss how this might have implications for the amplitude of the gravitational wave background detected by Pulsar Timing Arrays (PTA) experiments. We finally measure the corresponding value of the viscosity parameter $\alpha$ in our simulations and discuss how this depends on the binary properties., Comment: 7 pages, A&A submitted

In the age of artificial intelligence, the role of large language models (LLMs) is becoming increasingly central. Despite their growing prevalence, their capacity to consolidate knowledge from different training documents - a crucial ability in numerous applications - remains unexplored. This paper presents the first study examining the capability of LLMs to effectively combine such information within their parameter space. We introduce EpiK-Eval, a novel question-answering benchmark tailored to evaluate LLMs' proficiency in formulating a coherent and consistent knowledge representation from segmented narratives. Evaluations across various LLMs reveal significant weaknesses in this domain. We contend that these shortcomings stem from the intrinsic nature of prevailing training objectives. Consequently, we advocate for refining the approach towards knowledge consolidation, as it harbors the potential to dramatically improve their overall effectiveness and performance. The findings from this study offer insights for developing more robust and reliable LLMs. Our code and benchmark are available at https://github.com/chandar-lab/EpiK-Eval

Nonlocal metasurfaces are currently emerging as advanced tools for the manipulation of electromagnetic radiation, going beyond the widely explored Huygens metasurface concept. Nonetheless, the lack of an unified approach for their fast and efficient tunability still represents a serious challenge to overcome. In this article we report on gigahertz modulation of a dielectric slab-based, nonlocal (i.e. angle-dispersive) metasurface, whose operation relies on the optomechanical coupling with a mechanical wave excited piezoelectrically by a transducer integrated on the same chip. Importantly, the metasurface region is free from any conductive material, thus eliminating optical losses, and making our device of potential interest for delicate environments such as high-power apparatuses or quantum optical systems.

We consider a well posed SPDE$\colon dZ=(AZ+b(Z)) dt+dW(t),\,Z_0=x, $ on a separable Hilbert space $H$, where $A\colon H\to H$ is self-adjoint, negative and such that $A^{-1+\beta}$ is of trace class for some $\beta>0$, $b\colon H\to H$ is Lipschitz continuous and $W$ is a cylindrical Wiener process on $H$. We denote by $W_A(t)=\int_0^te^{(t-s)A}\,dW(s),\,t\in[0,T],$ the stochastic convolution. We prove, with the help of a formula for nonlinear transformations of Gaussian integrals due to R. Ramer, the following identity $$(P\circ Z_x^{-1})(\Phi) =\int_X\Phi(h+e^{\cdot A}x)\, \exp\left\{ -\tfrac12|\gamma_x(h)|^2_{ H_{Q_T}} + I(\gamma_x)(h)\right\} N_{Q_T}(dh), $$ where $ N_{Q_T}$ is the law of $W_A$ in $C([0,T],H)$, $ H_{Q_T}$ its Cameron--Martin space, $$ [\gamma_x(k)](t)=\int_0^t e^{(t-s)A}b(k(s)+e^{sA}x) ds,\quad t\in[0,T], \; k \in C([0,T],H) $$ and $I(\gamma_x) $ is the It\^o integral of $\gamma_x$. Some applications are discussed; in particular, when $b$ is dissipative we provide an explicit formula for the law of the stationary process and the invariant measure $\nu$ of the Markov semigroup $(P_t)$. Some concluding remarks are devoted to a similar problem with colored noise.

Single quantum emitters embedded in solid-state hosts are an ideal platform for realizing quantum information processors and quantum network nodes. Among the currently-investigated candidates, Er$^{3+}$ ions are particularly appealing due to their 1.5 $\mu$m optical transition in the telecom band as well as their long spin coherence times. However, the long lifetimes of the excited state -- generally in excess of 1 ms -- along with the inhomogeneous broadening of the optical transition result in significant challenges. Photon emission rates are prohibitively small, and different emitters generally create photons with distinct spectra, thereby preventing multi-photon interference -- a requirement for building large-scale, multi-node quantum networks. Here we solve this challenge by demonstrating for the first time linear Stark tuning of the emission frequency of a single Er$^{3+}$ ion. Our ions are embedded in a lithium niobate crystal and couple evanescently to a silicon nano-photonic crystal cavity that provides an up to 143 increase of the measured decay rate. By applying an electric field along the crystal c-axis, we achieve a Stark tuning greater than the ion's linewidth without changing the single-photon emission statistics of the ion. These results are a key step towards rare earth ion-based quantum networks.

The stellar companion to the weak-line T Tauri star DI Tau A was first discovered by the lunar occultation technique in 1989 and was subsequently confirmed by a speckle imaging observation in 1991. It has not been detected since, despite being targeted by five different studies that used a variety of methods and spanned more than 20 years. Here, we report the serendipitous rediscovery of DI Tau B during our Young Exoplanets Spectroscopic Survey (YESS). Using radial velocity data from YESS spanning 17 years, new adaptive optics observations from Keck II, and a variety of other data from the literature, we derive a preliminary orbital solution for the system that effectively explains the detection and (almost all of the) non-detection history of DI Tau B. We estimate the dynamical masses of both components, finding that the large mass difference (q $\sim$0.17) and long orbital period ($\gtrsim$35 years) make DI Tau system a noteworthy and valuable addition to studies of stellar evolution and pre-main-sequence models. With a long orbital period and a small flux ratio (f2/f1) between DI Tau A and B, additional measurements are needed for a better comparison between these observational results and pre-main-sequence models. Finally, we report an average surface magnetic field strength ($\bar B$) for DI Tau A, of $\sim$0.55 kG, which is unusually low in the context of young active stars., Comment: 21 pages, 10 figures. Accepted to ApJ

In this paper we introduce a novel abstract descent scheme suited for the minimization of proper and lower semicontinuous functions. The proposed abstract scheme generalizes a set of properties that are crucial for the convergence of several first-order methods designed for nonsmooth nonconvex optimization problems. Such properties guarantee the convergence of the full sequence of iterates to a stationary point, if the objective function satisfies the Kurdyka-Lojasiewicz property. The abstract framework allows for the design of new algorithms. We propose two inertial-type algorithms with implementable inexactness criteria for the main iteration update step. The first algorithm, i$^2$Piano, exploits large steps by adjusting a local Lipschitz constant. The second algorithm, iPila, overcomes the main drawback of line-search based methods by enforcing a descent only on a merit function instead of the objective function. Both algorithms have the potential to escape local minimizers (or stationary points) by leveraging the inertial feature. Moreover, they are proved to enjoy the full convergence guarantees of the abstract descent scheme, which is the best we can expect in such a general nonsmooth nonconvex optimization setup using first-order methods. The efficiency of the proposed algorithms is demonstrated on two exemplary image deblurring problems, where we can appreciate the benefits of performing a linesearch along the descent direction inside an inertial scheme., Comment: 37 pages, 8 figures

We generalize Laurent monomials to toric quasifolds, a special class of highly singular spaces that extend simplicial toric varieties to the nonrational setting., Comment: 17 pages, 5 figures, 1 table

We used the Immersion GRating Infrared Spectrometer (IGRINS) to determine fundamental parameters for 61 K- and M-type young stellar objects (YSOs) located in the Ophiuchus and Upper Scorpius star-forming regions. We employed synthetic spectra and a Markov chain Monte Carlo approach to fit specific K-band spectral regions and determine the photospheric temperature ($T_{\rm eff}$), surface gravity ($\log$ g), magnetic field strength (B), projected rotational velocity ($v \sin i$), and K-band veiling ($r_{\rm K}$). We determined B for $\sim$46% of our sample. Stellar parameters were compared to the results from Taurus-Auriga and the TW Hydrae Association (TWA) presented in Paper I of this series. We classified all the YSOs in the IGRINS survey with infrared spectral indices from 2MASS and WISE photometry between 2 and 24~$\mu$m. We found that Class II YSOs typically have lower $\log$ g and $v\sin i$, similar B, and higher K-band veiling than their Class III counterparts. Additionally, we determined the stellar parameters for a sample of K and M field stars also observed with IGRINS. We have identified intrinsic similarities and differences at different evolutionary stages with our homogeneous determination of stellar parameters in the IGRINS YSO Survey. Considering $\log$ g as a proxy for age, we found that the Ophiuchus and Taurus samples have a similar age. We also find that Upper Scorpius and TWA YSOs have similar ages, and are more evolved than Ophiuchus/Taurus YSOs., Comment: 21 pages, 8 figures, 4 tables. Accepted for publication in ApJ

Electrocatalytic CO$_2$RR is an interfacial process, involving a minimum of three phases at the contact point of gaseous CO$_2$ with the electrodic surface and the liquid electrolyte. As a consequence, surface chemistry at composite interfaces plays a central role for CO$_2$RR selectivity and catalysis. Each interface defines a functional boundary, where active sites are exposed to a unique environment with respect to distal sites in the bulk or organic and inorganic materials. While the individual role of each component-type is hardly predictable a-solo, the interface ensemble works via a strategic interplay of individual effects, including: (i) enhanced electrical conductivity, (ii) high surface area and exposure of the interfacial catalytic sites, (iii) favorable transport and feeding of reactants, (iv) complementary interactions for the on/off stabilization of cascade intermediates, (v) a secondary sphere assistance to lower the activation energy of bottleneck steps, (vi) a reinforced robustness and long-term operation stability by mutual protection and/or healing mechanisms. Selected CO$_2$RR case studies are compared and contrasted to highlight how the organic domains of carbon nanostructures merge with metal and metal-oxide active sites to separate tasks but also to turn them into a cooperative asset of mutual interactions, thus going beyond the classic Divide et Impera rule.

Census and Household Travel Survey datasets are regularly collected from households and individuals and provide information on their daily travel behavior with demographic and economic characteristics. These datasets have important applications ranging from travel demand estimation to agent-based modeling. However, they often represent a limited sample of the population due to privacy concerns or are given aggregated. Synthetic data augmentation is a promising avenue in addressing these challenges. In this paper, we propose a framework to generate a synthetic population that includes both socioeconomic features (e.g., age, sex, industry) and trip chains (i.e., activity locations). Our model is tested and compared with other recently proposed models on multiple assessment metrics.

Transformers have become one of the dominant architectures in the field of computer vision. However, there are yet several challenges when applying such architectures to video data. Most notably, these models struggle to model the temporal patterns of video data effectively. Directly targeting this issue, we introduce PatchBlender, a learnable blending function that operates over patch embeddings across the temporal dimension of the latent space. We show that our method is successful at enabling vision transformers to encode the temporal component of video data. On Something-Something v2 and MOVi-A, we show that our method improves the baseline performance of video Transformers. PatchBlender has the advantage of being compatible with almost any Transformer architecture and since it is learnable, the model can adaptively turn on or off the prior. It is also extremely lightweight compute-wise, 0.005% the GFLOPs of a ViT-B.

In this paper we present a bilevel optimization scheme for the solution of a general image deblurring problem, in which a parametric variational-like approach is encapsulated within a machine learning scheme to provide a high quality reconstructed image with automatically learned parameters. The ingredients of the variational lower level and the machine learning upper one are specifically chosen for the Helsinki Deblur Challenge 2021, in which sequences of letters are asked to be recovered from out-of-focus photographs with increasing levels of blur. Our proposed procedure for the reconstructed image consists in a fixed number of FISTA iterations applied to the minimization of an edge preserving and binarization enforcing regularized least-squares functional. The parameters defining the variational model and the optimization steps, which, unlike most deep learning approaches, all have a precise and interpretable meaning, are learned via either a similarity index or a support vector machine strategy. Numerical experiments on the test images provided by the challenge authors show significant gains with respect to a standard variational approach and performances comparable with those of some of the proposed deep learning based algorithms which require the optimization of millions of parameters.