Miracle-dz/UniFAR-FTUs huggingface dataset:
Dynamical decoupling design for identifying weakly coupled nuclear spins in a bath

Identifying weakly coupled nuclear spins around single electron spins is a key step toward implementing quantum information processing using coupled electron-nuclei spin systems or sensing like single-spin nuclear magnetic resonance detection using diamond defect spins. Dynamical decoupling control of the center electron spin with periodic pulse sequences [e.g., the Carre-Purcell-Meiboom-Gill (CPMG) sequence] has been successfully used to identify single nuclear spins and to resolve structure of nuclear spin clusters. Here, we design a type of pulse sequence by replacing the repetition unit (a single $\ensuremath{\pi}$ pulse) of the CPMG sequence with a group of nonuniformly spaced $\ensuremath{\pi}$ pulses. Using the nitrogen-vacancy center system in diamond, we theoretically demonstrate that the designed pulse sequence improves the resolution of nuclear spin noise spectroscopy, and more information about the surrounding nuclear spins is extracted. The principle of dynamical decoupling design proposed in this paper is useful in many systems (e.g., defect spin qubit in solids, trapped ion, and superconducting qubit) for high-resolution noise spectroscopy.
3D MHD simulations of planet migration in turbulent stratified disks

Abstract We performed 3D MHD numerical simulations of planet migration in stratified disks using the Godunov code PLUTO (Mignone et al. 2007). The disk is invaded by turbulence generated by the magnetorotational instability (MRI). We study the migration for planets with different mass to primary mass ratio. The migration of the low-mass planet (q=Mp/Ms=10−5) is dominated by random fluctuations in the torque and there is no defined direction of migration on timescales of 100 orbits. The intermediate-mass planet (q=Mp/Ms=10−4) can experience systematic outwards migration that was sustained for the times we were able to simulate.
Non-Markovian reservoir-dependent squeezing

The squeezing dynamics of a damped harmonic oscillator are studied for different types of environment without making the Markovian approximation. The squeezing dynamics of a coherent state depend on the reservoir spectrum in a unique way that can, in the weak coupling approximation, be analysed analytically. Comparison of squeezing dynamics for ohmic, sub-ohmic and super-ohmic environments is done, showing a clear connection between the squeezing–non-squeezing oscillations and reservoir structure. Understanding the effects occurring due to structured reservoirs is important both from a purely theoretical point of view and in connection with evolving experimental techniques and future quantum computing applications.
Defect-induced conductivity anisotropy in MoS2monolayers

Various types of defects in MoS2 monolayers and their influence on the electronic structure and transport properties have been studied using the Density-Functional based Tight-Binding method in conjunction with the Green's Function approach. Intrinsic defects in MoS2 monolayers significantly affect their electronic properties. Even at low concentration they considerably alter the quantum conductance. While the electron transport is practically isotropic in pristine MoS2, strong anisotropy is observed in the presence of defects. Localized mid-gap states are observed in semiconducting MoS2 that do not contribute to the conductivity but direction-dependent scatter the current, and that the conductivity is strongly reduced across line defects and selected grain boundary models.
Probing leptophilic dark sectors at electron beam-dump facilities

Medium-energy electron beam-dump experiments provide an intense sources of secondary muons. These particles can be used to search for muon-coupling light dark scalars that may explain the $(g-2)_\mu$ anomaly. We applied this idea to SLAC E137 experiment deriving new exclusion limits and evaluated the expected sensitivity for the planned Jefferson Lab BDX experiment (in case of null result report). The calculation is based on numerical simulations that include a realistic description of secondary muons generation in the dump, dark scalar production, propagation, and decay, and, finally, the decay products (electrons, positrons, or photons) interaction with the detector. For both experiments, exclusion limits were extended to cover a broader area in the scalar-to-muon coupling vs. scalar mass parameter space. This study demonstrates that electron beam-dump experiments have an enhanced sensitivity to new physics in processes that are usually studied using proton beams.
Relic Densities of Dark Matter in the U(1)-Extended NMSSM and the Gauged Axion Supermultiplet

We compute the dark matter relic densities of neutralinos and axions in a supersymmetric model with a gauged anomalous U(1) symmetry. The model is a variant of the USSM [the U(1) extended NMSSM], containing an extra U(1) symmetry and an extra singlet in the superpotential with respect to the MSSM, where gauge invariance is restored by Peccei-Quinn interactions using a St\"uckelberg multiplet. This approach introduces an axion ($\mathrm{Im}b$) and a saxion ($\mathrm{Re}b$) in the spectrum and generates an axino component for the neutralino. The St\"uckelberg axion ($\mathrm{Im}b$) develops a physical component (the gauged axion) after electroweak symmetry breaking. We classify all the interactions of the Lagrangian and perform a complete simulation study of the spectrum, determining the neutralino relic densities using micrOMEGAs. We discuss the phenomenological implications of the model analyzing mass values for the axion from the milli-eV to the MeV region. These depend sensitively on the value of $\mathrm{tan}﻿\ensuremath{\beta}$. The possible scenarios that we analyze are significantly constrained by a combination of WMAP data, the exclusion limits from direct axion searches, and the veto on late entropy release at the time of nucleosynthesis.
Enumeration of hybrid domino-lozenge tilings III: centrally symmetric tilings

We use the subgraph replacement method to investigate new properties of the tilings of regions on the square lattice with diagonals drawn in. In particular, we show that the centrally symmetric tilings of a generalization of the Aztec diamond are always enumerated by a simple product formula. This result generalizes the previous work of M. Ciucu and B. -Y. Yang about symmetric tilings of the Aztec diamond. We also use our method to prove a closed form product formula for the number of centrally symmetric tilings of a quasi-hexagon.
Graph polynomials and link invariants as positive type functions on Thompson’s group F

In a recent paper, Jones introduced a correspondence between elements of the Thompson group [Formula: see text] and certain graphs/links. It follows from his work that several polynomial invariants of links, such as the Kauffman bracket, can be reinterpreted as coefficients of certain unitary representations of [Formula: see text]. We give a somewhat different and elementary proof of this fact for the Kauffman bracket evaluated at certain roots of unity by means of a statistical mechanics model interpretation. Moreover, by similar methods we show that, for some particular specializations of the variables, other familiar link invariants and graph polynomials, namely the number of [Formula: see text]-colorings and the Tutte polynomial, can be viewed as positive definite functions on [Formula: see text].
Normal distribution of correlation measures of binary sum-of-digits functions

In this paper we study correlation measures introduced in [11]. Denote by $\mu_a(d)$ the asymptotic density of the set $\mathcal{E}_{a,d}=\{n \in \mathbb{N}, \ s_2(n+a)-s_2(n)=d\}$ (where $s_2$ is the sum-of-digits function in base 2). Then, for any point $X$ in $\{0,1\}^\mathbb{N}$, define the integer sequence $\left(a_X (n)\right)_{n\in \mathbb{N}}$ such that the binary decomposition of $a_X (n) $ is the prefix of length $n$ of $X$. We prove that for \textit{any} shift-invariant ergodic probability measure $\nu$ on $\{0,1\}^\mathbb{N}$, the sequence $\left(\mu_{a_X(n)}\right)_{n \in \mathbb{N}}$ satisfies a central limit theorem. This result was proven in the case where $\nu$ is the symmetric Bernoulli measure in [10].
Optimally Influencing Complex Ising Systems

In the study of social networks, a fundamental problem is that of influence maximization (IM): How can we maximize the collective opinion of individuals in a network given constrained marketing resources? Traditionally, the IM problem has been studied in the context of contagion models, which treat opinions as irreversible viruses that propagate through the network. To study reverberant opinion dynamics, which yield complex macroscopic behavior, the IM problem has recently been proposed in the context of the Ising model of opinion dynamics, in which individual opinions are treated as spins in an Ising system. In this paper, we are among the first to explore the \textit{Ising influence maximization (IIM)} problem, which has a natural physical interpretation as the maximization of the magnetization given a budget of external magnetic field, and we are the first to consider the IIM problem in general Ising systems with negative couplings and negative external fields. For a general Ising system, we show analytically that the optimal external field (i.e., that which maximizes the magnetization) exhibits a phase shift from intuitively focusing on high-degree nodes at high temperatures to counterintuitively focusing on "loosely-connected" nodes, which are weakly energetically bound to the ground state, at low temperatures. We also present a novel and efficient algorithm for solving IIM with provable performance guarantees for ferromagnetic systems in nonnegative external fields. We apply our algorithm on large random and real-world networks, verifying the existence of phase shifts in the optimal external fields and comparing the performance of our algorithm with the state-of-the-art mean-field-based algorithm.
Branching ratios and direct CP asymmetries in D -> PV decays

We study the two-body hadronic D -> PV decays, where P (V) denotes a pseudoscalar (vector) meson, in the factorization- assisted topological- amplitude approach proposed in our previous work. This approach is based on the factorization of short- distance and long- distance dynamics into Wilson coefficients and hadronic matrix elements of four-fermion operators, respectively, with the latter being parametrized in terms of several nonperturbative quantities. We further take into account the rho-omega mixing effect, which improves the global fit to the branching ratios involving the rho(0) and omega mesons. Combining short- distance dynamics associated with penguin operators and the hadronic parameters determined from the global fit to branching ratios, we predict direct CP asymmetries. In particular, the direct CP asymmetries in the D-0 -> K-0(K) over bar*(0), K-0(K) over bar*(0) -> pi(+) rho(0), and D-s(+) -> K+omega, K+phi decays are found to be of O(10(-3)), which can be observed at the LHCb and future Belle II experiment. We also predict the CP asymmetry observables of some neutral D meson decays.
ALMA Detection of a Linearly Polarized Reverse Shock in GRB 190114C

We present Atacama Large Millimeter/submillimeter Array 97.5 GHz total intensity and linear polarization observations of the mm-band afterglow of GRB 190114C spanning 2.2–5.2 hr after the burst. We detect linear polarization at the ≈5σ level, decreasing from Π = (0.87 ± 0.13)% to (0.60 ± 0.19)%, and evolving in polarization position angle from (10 ± 5)° to (−44 ± 12)° during the course of the observations. This represents the first detection and measurement of the temporal evolution of polarized radio/millimeter emission in a γ-ray burst. We show that the optical and X-ray observations between 0.03 days and ∼0.3 days are consistent with a fast-cooling forward shock expanding into a wind environment. However, the optical observations at ≲0.03 days, as well as the radio and millimeter observations, arise from a separate component, which we interpret as emission from the reverse-shocked ejecta. Using the measured linear polarization, we constrain the coherence scale of tangled magnetic fields in the ejecta to an angular size of θB ≈ 10−3 radian, while the rotation of the polarization angle rules out the presence of large-scale, ordered axisymmetric magnetic fields, and in particular a large-scale toroidal field, in the jet.
Investigating Student Learning about Disease Spread and Prevention in the Context of Agent-Based Computational Modeling

COVID-19 has brought increased attention to the importance of health literacy, including understanding of the transmission and prevention of disease. This study presents data from a project aimed at developing a computational modeling microworld to help middle school students learn about these topics. Specifically, the microworld is meant to help students model and test their ideas about how a disease spreads through a population and how an epidemic can be prevented. The paper analyzes one student's knowledge refinement through the building, testing, and debugging of a disease spread and prevention model. We model student refinement of thinking through steps of building initial models and predicting results, testing initial models and making sense of the results, debugging and retesting models, observing final models, and explaining results. Our findings suggest adolescents can learn about strategies for disease prevention through computational modeling. © ISLS.
Evolution of blue supergiants and α Cygni variables: puzzling CNO surface abundances

A massive star can enter the blue supergiant region either evolving directly from the main-sequence, or evolving from a previous red supergiant stage. The fractions of the blue supergiants having different histories depend on the internal mixing and mass-loss during the red supergiant stage. We study the possibility to use diagnostics based on stellar pulsation to discriminate blue supergiants having different evolution histories. For this purpose we have studied the pulsation property of massive star models calculated with the Geneva stellar evolution code for initial masses ranging from 8 to 50M⊙ with a solar metallicity of Z = 0.014. We have found that radial pulsations are excited in the blue-supergiant region only in the models that had been red-supergiants before. This would provide us with a useful mean to diagnose the history of evolution of each blue-supergiant. At a given effective temperature, much more nonradial pulsations are excited in the model after the red-supergiant stage than in the model evolving towards the red-supergiant. The properties of radial and nonradial pulsations in blue supergiants are discussed. Predicted periods are compared with period ranges observed in some α-Cygni variables in the Galaxy and NGC300. We have found that blue supergiant models after the red-supergiant stage roughly agree with observed period ranges in most cases. However, we are left with the puzzle that the predicted surface N/C and N/O ratios seem to be too high compared with those of Deneb and Rigel.
Healthcare utilization by children with neurological impairments and disabilities in rural Kenya: a retrospective cohort study combined with secondary analysis of audit data [version 1; peer review: awaiting peer review]

Background : There is a paucity of data on healthcare utilization by children with neurological impairments (NI) in sub-Saharan Africa. We determined the rate, risk factors, causes, and outcomes of hospital admission and utilization patterns for rehabilitative care among children with NI in a defined rural area in Kenya. Methods : We designed two sub-studies to address the primary objectives. Firstly, we retrospectively observed 251 children aged 6–9 years with NI and 2162 age-matched controls to determine the rate, causes and outcomes of hospitalization in a local referral hospital. The two cohorts were identified from an epidemiological survey conducted in 2015 in a defined geographical area. Secondly, we reviewed hospital records to characterize utilization patterns for rehabilitative care. Results : Thirty-four in-patient admissions occurred in 8503 person-years of observation (PYO), yielding a crude rate of 400 admissions per 100 000 PYO (95% confidence interval (Cl): 286–560). The risk of admission was similar between developmental Health education (87%), rehabilitative exercises (79%) and assistive technology (64%) were the most common interventions. Conclusions : Surprisingly, the risk of hospitalization was not different between children with NI and those without, possibly because those with severe NI who died before this follow-up were under seclusion and restraint in the community. Evidence-based and tailored rehabilitative interventions are urgently required based on the existing secondary data.
Ultraspinning instability of rotating black holes

Rapidly rotating Myers-Perry black holes in d{>=}6 dimensions were conjectured to be unstable by Emparan and Myers. In a previous publication, we found numerically the onset of the axisymmetric ultraspinning instability in the singly spinning Myers-Perry black hole in d=7, 8, 9. This threshold also signals a bifurcation to new branches of axisymmetric solutions with pinched horizons that are conjectured to connect to the black ring, black Saturn and other families in the phase diagram of stationary solutions. We firmly establish that this instability is also present in d=6 and in d=10, 11. The boundary conditions of the perturbations are discussed in detail for the first time, and we prove that they preserve the angular velocity and temperature of the original Myers-Perry black hole. This property is fundamental to establishing a thermodynamic necessary condition for the existence of this instability in general rotating backgrounds. We also prove a previous claim that the ultraspinning modes cannot be pure gauge modes. Finally we find new ultraspinning Gregory-Laflamme instabilities of rotating black strings and branes that appear exactly at the critical rotation predicted by the aforementioned thermodynamic criterium. The latter is a refinement of the Gubser-Mitra conjecture.
Tuning Valley Polarization in a WSe 2 Monolayer with a Tiny Magnetic Field

In monolayers of semiconducting transition metal dichalcogenides, the light helicity ($\sigma^+$ or $\sigma^-$) is locked to the valley degree of freedom, leading to the possibility of optical initialization of distinct valley populations. However, an extremely rapid valley pseudospin relaxation (at the time scale of picoseconds) occurring for optically bright (electric-dipole active) excitons imposes some limitations on the development of opto-valleytronics. Here we show that inter-valley scattering of excitons can be significantly suppressed in a $\mathrm{WSe}_2$ monolayer, a direct-gap two-dimensional semiconductor with the exciton ground state being optically dark. We demonstrate that the already inefficient relaxation of the exciton pseudospin in such system can be suppressed even further by the application of a tiny magnetic field of $\sim$100 mT. Time-resolved spectroscopy reveals the pseudospin dynamics to be a two-step relaxation process. An initial decay of the pseudospin occurs at the level of dark excitons on a time scale of 100 ps, which is tunable with a magnetic field. This decay is followed by even longer decay ($>1$ ns), once the dark excitons form more complex objects allowing for their radiative recombination. Our finding of slow valley pseudospin relaxation easily manipulated by the magnetic field open new prospects for engineering the dynamics of the valley pseudospin in transition metal dichalcogenides.
Supplementary Material of Pure Transformer with Integrated Experts for Scene Text Recognition

Multiple PTIE models were trained with varying number of layers for the encoder and decoder noting that both have the same number of layers. The results of the latency and weighted average accuracy are shown in Table A1. The PTIE models show a trade-off between accuracy to number of parameters and latency. All the PTIE models are competitive/outperform other recent works that are open source in terms of accuracy.
Immigrant Enfranchisement and Integration: Evidence from Italy

We study the consequences of immigrant enfranchisement by exploiting Romania’s accession to the EU in 2007, which granted municipal election voting rights to Romanian immigrants in Italy. We conduct an event-study analysis at the municipality-by-year level and reach three key findings. First, we find that the enfranchisement of Romanian immigrants leads to an increase in the likelihood of electing a Romanian-born councilor in municipal elections, with higher increases for municipalities expecting a competitive election. Using an instrumented difference-in-differences approach, we find the increase in representation is driven by enfranchisement of the preexisting population and not by new Romanian arrivals following the accession. Second, we find that social capital among Romanian immigrants increases after 2007, indicating that the effect of enfranchisement extends beyond political representation to integration. However, despite the increase in representation and social capital, we find that immigrant presence increases the likelihood of a right-leaning party victory, raises municipal spending on public security, and lowers spending on social programs. This suggests that natives’ backlash against immigrant presence plays a bigger role in determining the winning party than the existence of a newly enfranchised immigrant community. ∗Department of Economics, Brown University. Email: francesco ferlenga@brown.edu . †Department of Economics, Brown University. Email: stephanie hamin kang@brown.edu. Acknowledgement: We are grateful to Pedro Dal Bó, Brian Knight, and Stelios Michalopoulos for research guidance and discussions. We would also like to thank Peter Hull, Andrew Foster, and the seminar participants at Brown University. All mistakes are our own.
Estimating the Eﬀect of a Universal Cash Transfer on Birth Outcomes

Though the association between income and newborn health is well documented, causal estimation of the relationship is limited. We estimate the causal eﬀect of receiving additional income through a universal cash transfer on newborn health. In doing so, we advance a theoretical model whereby a cohort’s health at birth is a function of two primary mechanisms. The ﬁrst mechanism is a fertility selection process whereby some people have a child and others do not and whereby some fetuses survive to a live birth and others do not. This indirectly aﬀects the newborn cohort’s health. The second mechanism is the more traditionally studied prenatal response mechanism that directly aﬀects a newborn cohort’s health. We examine both mechanisms with the case of the Alaska Permanent Fund Dividend, a program that has provided all Alaskan residents with substantial annual cash payments since 1982. The amount of the payment varies year to year and is exogenous to individual Alaskans and the local economy. After integrating the fertility and prenatal response mechanisms empirically, we ﬁnd receiving a cash payment during pregnancy has no meaningful eﬀect on birth outcomes (that is, the eﬀects are detectable but very small). These ﬁndings suggest that improving newborn health requires either earlier interventions or more resources.