cssi/SciSciGPT-SciSciNet huggingface dataset:
Telomere length set point regulation in human pluripotent stem cells critically depends on the shelterin protein TPP1

Telomere maintenance is essential for the long-term proliferation of human pluripotent stem cells, while their telomere length set point determines the proliferative capacity of their differentiated progeny. The shelterin protein TPP1 is required for telomere stability and elongation, but its role in establishing a telomere length set point remains elusive. Here, we characterize the contribution of the shorter isoform of TPP1 (TPP1S) and the amino acid L104 outside the TEL patch, TPP1's telomerase interaction domain, to telomere length control. We demonstrate that cells deficient for TPP1S (TPP1S knockout [KO]), as well as the complete TPP1 KO cell lines, undergo telomere shortening. However, TPP1S KO cells are able to stabilize short telomeres, while TPP1 KO cells die. We compare these phenotypes with those of TPP1L104A/L104A mutant cells, which have short and stable telomeres similar to the TPP1S KO. In contrast to TPP1S KO cells, TPP1L104A/L104A cells respond to increased telomerase levels and maintain protected telomeres. However, TPP1L104A/L104A shows altered sensitivity to expression changes of shelterin proteins suggesting the mutation causes a defect in telomere length feedback regulation. Together this highlights TPP1L104A/L104A as the first shelterin mutant engineered at the endogenous locus of human stem cells with an altered telomere length set point.
Do Governors Lead or Follow? Timing of Stay-at-Home Orders

I investigate the timing of the Stay-at-Home orders. I use daily Google search data to track early interest in the novel Coronavirus pandemic. I ask whether governors responded to heightened concern (i.e., following) or if their decisions are independent of citizen sentiment (i.e., leading). I show that Stay-at-Home orders were initiated sooner in states that saw early, heightened in the virus. This suggests that governors follow voters' opinions, preferences, and sentiments. Exploring potential heterogeneous effects, there is not a difference in the size of this effect between Republican and Democrat governors, nor is there a difference between those up for re-election in 2020 and those not. I do find that governor responsiveness is related to the state's economic freedom and the governor's approval rating just before the pandemic. In a novel environment without precedence, governors in the USA set policy in accord with voter preferences.
Implementing a negative pressure isolation space within a skilled nursing facility to control SARS-CoV-2 transmission.

Background Isolation space must be expanded during pandemics involving airborne transmission. Little to no work has been done to establish optimal design strategies and implementation plans to ease surge capacity and expand isolation capacity over long periods in congregate living facilities. The COVID-19 pandemic has an airborne transmission component and requires isolation, which is difficult to accomplish in skilled nursing facilities. Methods In this study we designed, implemented, and validated an isolation space at a skilled nursing facility in Lancaster, PA. The overall goal was to minimize disease transmission between residents and staff within the facility. We created an isolation space by modifying an existing HVAC system of the SNF. We measured pressure on-site and performed computational fluid dynamics and Lagrangian particle-based modeling to test containment and possible transmission extent given the isolation space is considered negative rather than individual rooms. Results Pressure data shows the isolation space maintained an average (standard deviation) hourly value of -2.3 Pa (0.12 Pa) pressure differential between it and the external hallway connected to the rest of the facility. No transmission of SARS-CoV-2 between residents isolated to the space occurred, nor did any transmission to the staff or other residents occur. The isolation space was successfully implemented and, as of writing, continues to be operational through the pandemic. Conclusion Skilled nursing facilities can be retrofitted to provide negative pressure isolation space in a reasonable time frame and a cost effective manner to minimize airborne disease transmission within that space.
Virtual Visits to Optimize Research Trial Offerings to Heart Failure Patients

Clinical trials are crucial for development of new treatments that impact patient outcomes. A pilot study was designed to explore the use of virtual visits to collect functional information on patients living with heart failure. Assessments used in HF trials are the six-minute hallway walk test (6MWT) and timed-up and go test (TUG). We hypothesized virtual 6MWT and TUG would be non-inferior to the patient's baseline, in-person testing. Patients were enrolled in an outpatient setting. Informed consent was obtained. Baseline consisted of NYHA assessment, surveys (EQ-5D-5L, KCCQ, FIFE & Mini Cog), TUG and 6MWT. Patients were issued supplies to set up TUG/6MWT course at home. Follow-up video visits occured 7 days and 14 days [+/- 3 days] post-baseline. Surveys (EQ-5D-5L, KCCQ & Frailty Index), TUG and 6MWT were completed. Study staff reviewed 6MWT/TUG course set up for accuracy. Patients were supervised for the entirety of their 6MWT/TUG. Of the 94 patients enrolled, 74 patients completed all 6MWT assessments. Patient characteristics were described using mean and SD. One-way repeated measures ANOVA compared mean differences of in-person and virtual 6MWT/TUG. 6MWT scores at baseline, Day 7 and Day 14 were 1052.3 ft., 1107.6 ft., and 1080.3 ft., respectively. One-way repeated measures ANOVA found no statistical difference between mean in-person and virtual 6MWT (p = 0.45). Mean TUG scores at baseline, Day 7 and Day 14 were 9.3 s., 10.83s, and 9.7s., respectively. One-way repeated measures ANOVA found a statistical difference between mean TUG scores (p = 0.03). TUG results show significant outliers potentially influenced by patient symptoms (SOB, fatigue). Patient acceptance was assessed by exit interview. Patients were comfortable with the use of virtual visits (56%), would be willing to participate in research studies through telemedicine (98.7%) and found the act of completing a study via virtual visit to be not difficult (77.3%). Virtual administration of the 6MWT was shown to be non-inferior to in-person administration. This approach could be adopted by industry-sponsored and investigator initiated research studies in heart failure cohorts. Increasing clinical trial enrollment barriers will improve patient care by including a more diverse patient population in study enrollment and decrease study follow up attrition rates.
Hypercluster: a flexible tool for parallelized unsupervised clustering optimization

Unsupervised clustering is a common and exceptionally useful tool for large biological datasets. However, clustering requires upfront algorithm and hyperparameter selection, which can introduce bias into the final clustering labels. It is therefore advisable to obtain a range of clustering results from multiple models and hyperparameters, which can be cumbersome and slow. We present hypercluster, a python package and SnakeMake pipeline for flexible and parallelized clustering evaluation and selection. Users can efficiently evaluate a huge range of clustering results from multiple models and hyperparameters to identify an optimal model. Hypercluster improves ease of use, robustness and reproducibility for unsupervised clustering application for high throughput biology. Hypercluster is available on pip and bioconda; installation, documentation and example workflows can be found at: https://github.com/ruggleslab/hypercluster .
On the rational relationships among pseudo-roots of a non-commutative polynomial

Abstract For a non-commutative ring R, we consider factorizations of polynomials in R [ t ] where t is a central variable. A pseudo-root of a polynomial p ( t ) = p 0 + p 1 t + ⋯ p k t k is an element ξ ∈ R , for which there exist polynomials q 1 , q 2 such that p = q 1 ( t − ξ ) q 2 . We investigate the rational relationships that hold among the pseudo-roots of p ( t ) by using the diamond operations for cover graphs of modular lattices. When R is a division ring, each finite subset S of R corresponds to a unique minimal monic polynomial f S that vanishes on S. By results of Leroy and Lam [16] , the set of polynomials { f T : T ⊆ S } with the right-divisibility order forms a lattice with join operation corresponding to (left) least common multiple and meet operation corresponding to (right) greatest common divisor. The set of edges of the cover graph of this lattice correspond naturally to a set Λ S of pseudo-roots of f S . Given an arbitrary subset of Λ S , our results provide a graph theoretic criterion that guarantees that the subset rationally generates all of Λ S , and in particular, rationally generates S.
Phenomenology of Magnetic Black Holes with Electroweak-Symmetric Coronas

Magnetically charged black holes (MBHs) are interesting solutions of the Standard Model and general relativity. They may possess a “hairy” electroweak-symmetric corona outside the event horizon, which speeds up their Hawking radiation and leads them to become nearly extremal on short timescales. Their masses could range from the Planck scale up to the Earth mass. We study various methods to search for primordially produced MBHs and estimate the upper limits on their abundance. We revisit the Parker bound on magnetic monopoles and show that it can be extended by several orders of magnitude using the large-scale coherent magnetic fields in Andromeda. This sets a mass-independent constraint that MBHs have an abundance less than 4 × 10−4 times that of dark matter. MBHs can also be captured in astrophysical systems like the Sun, the Earth, or neutron stars. There, they can become non-extremal either from merging with an oppositely charged MBH or absorbing nucleons. The resulting Hawking radiation can be detected as neutri- nos, photons, or heat. High-energy neutrino searches in particular can set a stronger bound than the Parker bound for some MBH masses, down to an abundance 10−7 of dark matter.
Point Cloud Segmentation based on Hypergraph Spectral Clustering

Goal: Segment the gray-scale point clouds, i.e., s = [ X 1 X 2 X 3 ] ∈ ℝ N×3 based on hypergraph spectral clustering.
Integrated-Photonic Characterization of Single-Photon Detectors for Use in Neuromorphic Synapses

Large-scale spiking neural networks have been designed based on superconducting-nanowire single-photon detectors (SNSPDs) as receiver elements for photonic communication between artificial neurons and synapses. Such large-scale artificial neural networks will require thousands of waveguide-integrated SNSPD devices on a single chip. Efficient waveguide-coupled SNSPDs and high-throughput methods for their characterization at this scale are very challenging. Here, we design, fabricate, and measure SNSPDs that are compatible with these large-scale networks. We demonstrate integrated-photonic circuits to simultaneously characterize many waveguide-coupled SNSPDs with a single-fiber input. We achieve up to 15 waveguide-coupled SNSPDs in a single integrated-photonic circuit and a total of 49 waveguide SNSPDs with a detection plateau out of 49 tested. This is perhaps the largest number of SNSPDs integrated in a photonic circuit to date. We employ several types of photonic circuits to enable rapid and reliable characterization of detector performance. We further demonstrate several important synaptic functions of these detectors. These include a binary response in the detectors with average incident photon numbers ranging from less than ${10}^{\ensuremath{-}3}$ to greater than 10, indicating that synaptic responses based on these detectors are independent of the number of incident photons in a communication pulse. Such a binary response is ideal for communication in neural systems. We further demonstrate that the response has a linear dependence of the output-current pulse height on the bias current with up to a factor of 1.7 tunability in pulse height, a function that cannot be obtained without a detection plateau.
A Characterization of Multiplicity-Preserving Global Bifurcations of Complex Polynomial Vector Fields

For the space of single-variable monic and centered complex polynomial vector fields of arbitrary degree d, it is proved that any bifurcation which preserves the multiplicity of equilibrium points admits a decomposition into a finite number of elementary bifurcations, and the elementary bifurcations are characterized.
The KPZ Limit of ASEP with Boundary

It was recently proved in Corwin and Shen (CPAM, [CS16]) that under weakly asymmetric scaling, the height functions for ASEP with sources and sinks converges to the Hopf–Cole solution of the KPZ equation with inhomogeneous Neumann boundary conditions. In their assumptions [CS16] chose positive values for the Neumann boundary condition, and they assumed initial data which is close to stationarity. By developing more extensive heat-kernel estimates, we clarify and extend their results to negative values of the Neumann boundary parameters, and we also show how to generalize their results to empty initial data (which is very far from stationarity). Combining our result with Barraquand et al. (Duke Math J, [BBCW17]), we obtain the Laplace transform of the one-point distribution for half-line KPZ, and use this to confirm t1/3-scale GOE Tracy–Widom long-time fluctuations at the origin.
Fixed point proportions for Galois groups of non-geometric iterated extensions

Given a map $\varphi:\mathbb{P}^1\rightarrow \mathbb{P}^1$ of degree greater than 1 defined over a number field $k$, one can define a map $\varphi_\mathfrak{p}:\mathbb{P}^1(\mathfrak{o}_k/\mathfrak{p})\rightarrow \mathbb{P}^1(\mathfrak{o}_k/\mathfrak{p})$ for each prime $\mathfrak{p}$ of good reduction, induced by reduction modulo $\mathfrak{p}$. It has been shown that for a typical $\varphi$ the proportion of periodic points of $\varphi_\mathfrak{p}$ should tend to $0$ as $|\mathbb{P}^1(\mathfrak{o}_k/\mathfrak{p})|$ grows. In this paper, we extend previous results to include a weaker set of sufficient conditions under which this property holds. We are also able to show that these conditions are necessary for certain families of functions, for example, functions of the form $\varphi(x)=x^d+c$, where $0$ is not a preperiodic point of this map. We study the proportion of periodic points by looking at the fixed point proportion of the Galois groups of certain extensions associated to iterates of the map.
Magnetoresistance in single-layer graphene: weak localization and universal conductance fluctuation studies

We report measurements of magnetoresistance in single-layer graphene as a function of gate voltage (carrier density) at 250 mK. By examining signatures of weak localization (WL) and universal conductance fluctuations (UCF), we find a consistent picture of phase coherence loss due to electron–electron interactions. The gate dependence of the elastic scattering terms suggests that the effect of trigonal warping, i.e. the nonlinearity of the dispersion curves, may be strong at high carrier densities, while intra-valley scattering may dominate close to the Dirac point. In addition, a decrease in UCF amplitude with decreasing carrier density can be explained by a corresponding loss of phase coherence.
Factorization method versus migration imaging in a waveguide

We present a comparative study of two qualitative imaging methods in an acoustic waveguide with sound hard walls. The waveguide terminates at one end and contains unknown obstacles of compact support, to be determined from data gathered by an array of sensors that probe the obstacles with waves and measure the scattered response. The first imaging method, known as the factorization method, is based on the factorization of the far field operator. It is designed to image at single frequency and estimates the support of the obstacles by a Picard range criterion. The second imaging method, known as migration, works either with one or multiple frequencies. It forms an image by backpropagating the measured scattered wave to the search points, using the Green's function in the empty waveguide. We study the connection between these methods with analysis and numerical simulations.
Real space information from fluctuation electron microscopy: applications to amorphous silicon

Ideal models of complex materials must satisfy all available information about the system. Generally, this information consists of experimental data, information implicit to sophisticated interatomic interactions and potentially other a priori information. By jointly imposing first-principles or tight-binding information in conjunction with experimental data, we have developed a method: experimentally constrained molecular relaxation (ECMR) that uses all of the information available. We apply the method to model medium range order in amorphous silicon using fluctuation electron microscopy (FEM) data as experimental information. The paracrystalline model of medium range order is examined, and a new model based on voids in amorphous silicon is proposed. Our work suggests that films of amorphous silicon showing medium range order (in FEM experiments) can be accurately represented by a continuous random network model with inhomogeneities consisting of ordered grains and voids dispersed in the network.
Two‐Dimensional Simulations of Pair‐Instability Supernovae

We present preliminary results from two‐dimensional numerical studies of nuclear burning and hydrodynamic instabilities in pair‐instability supernova (PSN) performed with the new radiation‐hydrodynamics code CASTRO.
Visualizing the geometry of state space in plane Couette flow

Motivated by recent experimental and numerical studies of coherent structures in wall-bounded shear flows, we initiate a systematic exploration of the hierarchy of unstable invariant solutions of the Navier-Stokes equations. We construct a dynamical 10 5 -dimensional state-space representation of plane Couette flow at Reynolds number Re = 400 in a small periodic cell and offer a new method of visualizing invariant manifolds embedded in such high dimensions. We compute a new equilibrium solution of plane Couette flow and the leading eigenvalues and eigenfunctions of known equilibria at this Re and cell size. What emerges from global continuations of their unstable manifolds is a surprisingly elegant dynamical-systems visualization of moderate-Re turbulence. The invariant manifolds partially tessellate the region of state space explored by transiently turbulent dynamics with a rigid web of symmetry-induced heteroclinic connections.
SPQR - Spectroscopy: Prospects, Questions & Results

Tremendous progress has been made in mapping out the spectrum of hadrons over the past decade with plans to make further advances in the decade ahead. Baryons and mesons, both expected and unexpected, have been found, the results of precision experiments often with polarized beams, polarized targets and sometimes polarization of the final states. All these hadrons generate poles in the complex energy plane that are consequences of the strong coupling regime of QCD. They reveal how this works.
Emission Beam Geometry of Selected Pulsars Derived from Average Pulse Polarization Data

By fitting the classical rotating vector model (RVM) to high-quality polarization data for selected radio pulsars, we find the inclination of the magnetic axis to the spin axis, α, as well as the minimum angle between the line of sight and the magnetic axis, β, for 10 objects. We give a full treatment of statistical errors in the fitting process. We also present a dictionary and conversion table of various investigators' geometric definitions to facilitate future comparisons. We compare our results with other RVM fits and with empirical/geometrical (E/G) approaches, and we examine the strengths and weaknesses of RVM fits and E/G investigations for the determination of pulsar emission beam geometry. Our fits to B0950+08 show that it is an orthogonal rotator with the main and interpulse radiation emitted from opposite magnetic poles, whereas earlier RVM fits indicated that it is an almost-aligned, single-magnetic pole emitter. We demonstrate that low-level emission across a wide longitude range, when properly weighted in the RVM fit, conclusively favors the former scenario. B0823+26 is also an orthogonal rotator. We find that B1929+10 emits into its wide observed range of longitudes from portions of a single cone that is almost aligned with the spin axis. This result agrees with other RVM fits but conflicts with the E/G findings of Rankin & Rathnasree. We determine that convergent RVM solutions can be found only for a minority of pulsars: generally those having emission over a relatively wide longitude range, and especially those pulsars having interpulse emission. In pulsar B0823+26, our preferred fit to data at all longitudes yields a solution differing by several σ from a fit to the main pulse/postcursor combination alone. For pulsar B0950+08, separate fits to the main pulse region, the interpulse region, and our preferred fit to almost all longitudes, converge to results differing by several times the formal uncertainties. These results indicate that RVM fits are easily perturbed by systematic effects in polarized position angles and that the formal uncertainties significantly underestimate the actual errors.
Single-Degenerate Type Ia Supernovae Are Preferentially Overluminous

Recent observational and theoretical progress has favored merging and helium-accreting sub-Chandrasekhar mass white dwarfs (WDs) in the double-degenerate and the double-detonation channels, respectively, as the most promising progenitors of normal Type Ia supernovae (SNe Ia). Thus the fate of rapidly accreting Chandrasekhar mass WDs in the single-degenerate channel remains more mysterious then ever. In this paper, we clarify the nature of ignition in Chandrasekhar-mass single-degenerate SNe Ia by analytically deriving the existence of a characteristic length scale which establishes a transition from central ignitions to buoyancy-driven ignitions. Using this criterion, combined with data from three-dimensional simulations of convection and ignition, we demonstrate that the overwhelming majority of ignition events within Chandrasekhar-mass WDs in the single-degenerate channel are buoyancy-driven, and consequently lack a vigorous deflagration phase. We thus infer that single-degenerate SNe Ia are generally expected to lead to overluminous 1991T-like SNe Ia events. We establish that the rates predicted from both the population of supersoft X-ray sources (SSSs) and binary population synthesis models of the single-degenerate channel are broadly consistent with the observed rates of overluminous SNe Ia, and suggest that the population of SSSs are the dominant stellar progenitors of SNe 1991T-like events. We further demonstrate that the single-degenerate channel contribution to the normal and failed 2002cx-like rates is not likely to exceed 1% of the total SNe Ia rate. We conclude with a range of observational tests of overluminous SNe Ia which will either support or strongly constrain the single-degenerate scenario.
Mitigating the impact of the DESI fiber assignment on galaxy clustering

We present a simple strategy to mitigate the impact of an incomplete spectroscopic redshift galaxy sample as a result of fiber assignment and survey tiling. The method has been designed for the Dark Energy Spectroscopic Instrument (DESI) galaxy survey but may have applications beyond this. We propose a modification to the usual correlation function that nulls the almost purely angular modes affected by survey incompleteness due to fiber assignment. Predictions of this modified statistic can be calculated given a model of the two point correlation function. The new statistic can be computed with a slight modification to the data catalogues input to the standard correlation function code and does not incur any additional computational time. Finally we show that the spherically averaged baryon acoustic oscillation signal is not biased by the new statistic.
Strong accessibility for hyperbolic groups

We use an accessibility result of Delzant and Potyagailo to prove Swarup's Strong Accessibility Conjecture for Gromov hyperbolic groups with no 2-torsion. It follows that, if M is an irreducible, orientable, compact 3-manifold with hyperbolic fundamental group, then any hierarchy in which M is decomposed alternately along compressing disks and essential annuli is finite.
Connection topology of step edge state bands at the surface of a three dimensional topological insulator

Topological insulators (TIs) in the Bi2Se3 family manifest helical Dirac surface states that span the topologically ordered bulk band gap. Recent scanning tunneling microscopy measurements have discovered additional states in the bulk band gap of Bi2Se3 and Bi2Te3, localized at one-dimensional step edges. Here numerical simulations of a TI surface are used to explore the phenomenology of edge state formation at the single-quintuple layer step defects found ubiquitously on these materials. The modeled one-dimensional edge states are found to exhibit a stable topological connection to the two-dimensional surface state Dirac point.
Efficiency of the maximum partial likelihood estimator for nested case control sampling

In making inference on the relation between failure and exposure histories in the Cox semiparametric model, the maximum partial likelihood estimator (MPLE) of the finite dimensional odds parameter, and the Breslow estimator of the baseline survival function, are known to achieve full efficiency when data is available for all time on all cohort members, even when the covariates are time dependent. When cohort sizes become too large for the collection of complete data, sampling schemes such as nested case control sampling must be used and, under various models, there exist estimators based on the same information as the MPLE having smaller asymptotic variance. Though the MPLE is therefore not efficient under sampling in general, it approaches efficiency in highly stratified situations, or instances where the covariate values are increasingly less dependent upon the past, when the covariate distribution, not depending on the real parameter of interest, is unknown and there is no censoring. In particular, in such situations, when using the nested case control sampling design, both the MPLE and the Breslow estimator of the baseline survival function achieve the information lower bound both in the distributional and the minimax senses in the limit as the number of cohort members tends to infinity.
P-Type Tunnel FETs With Triple Heterojunctions

A triple-heterojunction (3HJ) design is employed to improve p-type InAs/GaSb heterojunction (HJ) tunnel FETs. Atomistic quantum transport simulations show, that the added two HJs (AlInAsSb/InAs in the source and GaSb/AlSb in the channel) significantly shorten the tunnel distance and create two resonant states, greatly improving the ON state tunneling probability. Moreover, the source Fermi degeneracy is reduced by the increased source (AlInAsSb) density of states and the OFF state leakage is reduced by the heavier channel (AlSb) hole effective masses. With $V_{\mathrm{DD}}=0.3\rm {V}$ and $I_{\mathrm{OFF}}=1\rm {nA/\mu m}$ , ballistic $I_{\mathrm{ON}}$ of $606\rm {\mu A/\mu m}$ ( $492\rm {\mu A/\mu m}$ ) is obtained at $30\rm {nm}$ ( $15\rm {nm}$ ) channel length, which is comparable to n-type 3HJ counterpart and significantly exceeding p-type silicon MOSFET. Simultaneously, the nonlinear turn on and delayed saturation in the output characteristics are also greatly improved.
Adiabatic projection method for scattering and reactions on the lattice

We demonstrate and test the adiabatic projection method, a general new framework for calculating scattering and reactions on the lattice. The method is based upon calculating a low-energy effective theory for clusters which becomes exact in the limit of large Euclidean projection time. As a detailed example we calculate the adiabatic two-body Hamiltonian for elastic fermion-dimer scattering in lattice effective field theory. Our calculation corresponds to neutron-deuteron scattering in the spin-quartet channel at leading order in pionless effective field theory. We show that the spectrum of the adiabatic Hamiltonian reproduces the spectrum of the original Hamiltonian below the inelastic threshold to arbitrary accuracy. We also show that the calculated s -wave phase shift reproduces the known exact result in the continuum and infinite-volume limits. When extended to more than one scattering channel, the adiabatic projection method can be used to calculate inelastic reactions on the lattice in future work.
Exploring the structure of misconceptions in the Force Concept Inventory with modified module analysis

Modified module analysis is applied to the Force Concept Inventory to understand the structure of the incorrect answers.
SEARCHING FOR THE 3.5 keV LINE IN THE STACKED SUZAKU OBSERVATIONS OF GALAXY CLUSTERS

We perform a detailed study of the stacked Suzaku observations of 47 galaxy clusters, spanning a redshift range of 0.01-0.45, to search for the unidentified 3.5 keV line. This sample provides an independent test for the previously detected line. We detect a 2sigma-significant spectral feature at 3.5 keV in the spectrum of the full sample. When the sample is divided into two subsamples (cool-core and non-cool core clusters), the cool-core subsample shows no statistically significant positive residuals at the line energy. A very weak (approx. 2sigma confidence) spectral feature at 3.5 keV is permitted by the data from the non-cool-core clusters sample. The upper limit on a neutrino decay mixing angle of sin(sup 2)(2theta) = 6.1 x 10(exp -11) from the full Suzaku sample is consistent with the previous detections in the stacked XMM-Newton sample of galaxy clusters (which had a higher statistical sensitivity to faint lines), M31, and Galactic center, at a 90% confidence level. However, the constraint from the present sample, which does not include the Perseus cluster, is in tension with previously reported line flux observed in the core of the Perseus cluster with XMM-Newton and Suzaku.
Spatially Extended Tests of a Neural Network Parametrization Trained by Coarse‐Graining

General circulation models (GCMs) typically have a grid size of 25--200 km. Parametrizations are used to represent diabatic processes such as radiative transfer and cloud microphysics and account for sub-grid-scale motions and variability. Unlike traditional approaches, neural networks (NNs) can readily exploit recent observational datasets and global cloud-system resolving model (CRM) simulations to learn subgrid variability. This article describes an NN parametrization trained by coarse-graining a near-global CRM simulation with a 4~km horizontal grid spacing. The NN predicts the residual heating and moistening averaged over (160 km)^2 grid boxes as a function of the coarse-resolution fields within the same atmospheric column. This NN is coupled to the dynamical core of a GCM with the same 160 km resolution. A recent study described how to train such an NN to be numerically stable when coupled to specified time-evolving advective forcings in a single column model, but feedbacks between NN and GCM components cause spatially-extended simulations to crash within a few days. Analyzing the linearized response of such an NN reveals that it learns to exploit a strong synchrony between precipitation and the atmospheric state above 10 km. Removing these variables from the NN's inputs stabilizes the coupled simulations, which predict the future state more accurately than a coarse-resolution simulation without any parametrizations of sub-grid-scale variability, although the mean state slowly drifts.
Entity Linking in 100 Languages

We propose a new formulation for multilingual entity linking, where language-specific mentions resolve to a language-agnostic Knowledge Base. We train a dual encoder in this new setting, building on prior work with improved feature representation, negative mining, and an auxiliary entity-pairing task, to obtain a single entity retrieval model that covers 100+ languages and 20 million entities. The model outperforms state-of-the-art results from a far more limited cross-lingual linking task. Rare entities and low-resource languages pose challenges at this large-scale, so we advocate for an increased focus on zero- and few-shot evaluation. To this end, we provide Mewsli-9, a large new multilingual dataset matched to our setting, and show how frequency-based analysis provided key insights for our model and training enhancements.
Mesa-top quantum dot single photon emitter arrays: Growth, optical characteristics, and the simulated optical response of integrated dielectric nanoantenna-waveguide systems

Nanophotonic quantum information processing systems require spatially ordered, spectrally uniform single photon sources (SPSs) integrated on-chip with co-designed light manipulating elements providing emission rate enhancement, emitted photon guidance, and lossless propagation. Towards this goal, we consider systems comprising an SPS array with each SPS coupled to a dielectric building block (DBB) based multifunctional light manipulation unit (LMU). For the SPS array, we report triggered single photon emission from GaAs(001)/InGaAs single quantum dots grown selectively on top of nanomesas using the approach of substrate-encoded size-reducing epitaxy (SESRE). Systematic temperature and power dependent photoluminescence (PL), PL excitation, time-resolved PL, and emission statistics studies reveal high spectral uniformity and single photon emission at 8 K with g(2)(0) of 0.19 ± 0.03. The SESRE based SPS arrays, following growth of a planarizing overlayer, are readily integrable with LMUs fabricated subsequen...
Kinematic Morphology of Large-scale Structure: Evolution from Potential to Rotational Flow

As an alternative way to describe the cosmological velocity field, we discuss the evolution of rotational invariants constructed from the velocity gradient tensor. Compared with the traditional divergence-vorticity decomposition, these invariants, defined as coefficients of the characteristic equation of the velocity gradient tensor, enable a complete classification of all possible flow patterns in the dark-matter comoving frame, including both potential and vortical flows. We show that this tool, first introduced in turbulence two decades ago, is very useful for understanding the evolution of the cosmic web structure, and in classifying its morphology. Before shell crossing, different categories of potential flow are highly associated with the cosmic web structure because of the coherent evolution of density and velocity. This correspondence is even preserved at some level when vorticity is generated after shell crossing. The evolution from the potential to vortical flow can be traced continuously by these invariants. With the help of this tool, we show that the vorticity is generated in a particular way that is highly correlated with the large-scale structure. This includes a distinct spatial distribution and different types of alignment between the cosmic web and vorticity direction for various vortical flows. Incorporating shell crossing into closed dynamical systems is highly non-trivial, but we propose a possible statistical explanation for some of the phenomena relating to the internal structure of the three-dimensional invariant space.
A species or weak-gravity bound for large N gauge theories coupled to gravity

Causality constrains the gravitational interactions of massive higher spin particles in both AdS and flat spacetime. We explore the extent to which these constraints apply to composite particles, explaining why they do not rule out macroscopic objects or hydrogen atoms. However, we find that they do apply to glueballs and mesons in confining large N gauge theories. Assuming such theories contain massive bound states of general spin, we find parametric bounds in (3 + 1) spacetime dimensions of the form $$ N\lesssim \frac{M_{Pl}}{\Lambda_{\mathrm{QCD}}} $$ relating N, the QCD scale, and the Planck scale. We also argue that a stronger bound replacing ∧QCD with the UV cut-off scale may be derived from eikonal scattering in flat spacetime.
Plasmoid Ejections and Loop Contractions in an Eruptive M7.7 Solar Flare: Evidence of Particle Acceleration and Heating in Magnetic Reconnection Outflows

Where particle acceleration and plasma heating take place in relation to magnetic reconnection is a fundamental question for solar flares. We report analysis of an M7.7 flare on 2012 July 19 observed by SDO/AIA and RHESSI. Bi-directional outflows in forms of plasmoid ejections and contracting cusp-shaped loops originate between an erupting flux rope and underlying flare loops at speeds of typically 200-300 km s–1 up to 1050 km s–1. These outflows are associated with spatially separated double coronal X-ray sources with centroid separation decreasing with energy. The highest temperature is located near the nonthermal X-ray loop-top source well below the original heights of contracting cusps near the inferred reconnection site. These observations suggest that the primary loci of particle acceleration and plasma heating are in the reconnection outflow regions, rather than the reconnection site itself. In addition, there is an initial ascent of the X-ray and EUV loop-top source prior to its recently recognized descent, which we ascribe to the interplay among multiple processes including the upward development of reconnection and the downward contractions of reconnected loops. The impulsive phase onset is delayed by 10 minutes from the start of the descent, but coincides with the rapid speed increases of the upward plasmoids, the individual loop shrinkages, and the overall loop-top descent, suggestive of an intimate relation of the energy release rate and reconnection outflow speed.
Branch Prediction Is Not A Solved Problem: Measurements, Opportunities, and Future Directions

Modern branch predictors predict the vast majority of conditional branch instructions with near-perfect accuracy, allowing superscalar, out-of-order processors to maximize speculative efficiency and thus performance. However, this impressive overall effectiveness belies a substantial missed opportunity in single-threaded instructions per cycle (IPC). For example, we show that correcting the mispredictions made by the state-of-the-art TAGE-SC-L branch predictor on SPECint 2017 would improve IPC by margins similar to an advance in process technology node. In this work, we measure and characterize these mispredictions. We find that they categorically arise from either (1) a small number of systematically hard-to-predict (H2P) branches; or (2) rare branches with low dynamic execution counts. Using data from SPECint 2017 and additional large code footprint applications, we quantify the occurrence and IPC impact of these two categories. We then demonstrate that solely increasing the resources afforded to existing branch predictors does not address the root causes of most mispredictions. This leads us to reexamine basic assumptions in branch prediction and to propose new research directions that, for example, deploy machine learning to improve pattern matching for H2Ps, and use on-chip phase learning to track long-term statistics for rare branches.
Using subsystem MT2 for complete mass determinations in decay chains with missing energy at hadron colliders

We propose to use the MT2 concept to measure the masses of all particles in SUSY-like events with two unobservable, identical particles. To this end we generalize the usual notion of MT2 and define a new MT2(n,p,c) variable, which can be applied to various subsystem topologies, as well as the full event topology. We derive analytic formulas for its endpoint MT2,max(n,p,c) as a function of the unknown test mass c of the final particle in the subchain and the transverse momentum pT due to radiation from the initial state. We show that the endpoint functions MT2,max(n,p,c)(c,pT) may exhibit three different types of kinks and discuss the origin of each type. We prove that the subsystem MT2(n,p,c) variables by themselves already yield a sufficient number of measurements for a complete determination of the mass spectrum (including the overall mass scale). As an illustration, we consider the simple case of a decay chain with up to three heavy particles, X2 → X1 → X0, which is rather problematic for all other mass measurement methods. We propose three different MT2-based methods, each of which allows a complete determination of the masses of particles X0, X1 and X2. The first method only uses MT2(n,p,c) endpoint measurements at a single fixed value of the test mass c. In the second method the unknown mass spectrum is fitted to one or more endpoint functions MT2,max(n,p,c)(c,pT) exhibiting a kink. The third method is hybrid, combining MT2 endpoints with measurements of kinematic edges in invariant mass distributions. As a practical application of our methods, we show that the dilepton W+W− and t samples at the Tevatron can be used for an independent determination of the masses of the top quark, the W boson and the neutrino, without any prior assumptions.
The wisdom of polarized crowds

As political polarization in the United States continues to rise1–3, the question of whether polarized individuals can fruitfully cooperate becomes pressing. Although diverse perspectives typically lead to superior team performance on complex tasks4,5, strong political perspectives have been associated with conflict, misinformation and a reluctance to engage with people and ideas beyond one’s echo chamber6–8. Here, we explore the effect of ideological composition on team performance by analysing millions of edits to Wikipedia’s political, social issues and science articles. We measure editors’ online ideological preferences by how much they contribute to conservative versus liberal articles. Editor surveys suggest that online contributions associate with offline political party affiliation and ideological self-identity. Our analysis reveals that polarized teams consisting of a balanced set of ideologically diverse editors produce articles of a higher quality than homogeneous teams. The effect is most clearly seen in Wikipedia’s political articles, but also in social issues and even science articles. Analysis of article ‘talk pages’ reveals that ideologically polarized teams engage in longer, more constructive, competitive and substantively focused but linguistically diverse debates than teams of ideological moderates. More intense use of Wikipedia policies by ideologically diverse teams suggests institutional design principles to help unleash the power of polarization. This article explores the effect of ideological polarization on team performance. By analysing millions of edits to Wikipedia, the authors reveal that politically diverse editor teams produce higher-quality articles than homogeneous or moderate teams, and they identify the mechanisms responsible for producing these superior articles.
A Morphological Analysis of Gamma-Ray Burst Early-optical Afterglows

Within the framework of the external shock model of gamma-ray bursts (GRBs) afterglows, we perform a morphological analysis of the early optical lightcurves to directly constrain model parameters. We define four morphological types, i.e. the reverse shock dominated cases with/without the emergence of the forward shock peak (Type I/ Type II), and the forward shock dominated cases without/with $\nu_m$ crossing the band (Type III/IV). We systematically investigate all the Swift GRBs that have optical detection earlier than 500 s and find 3/63 Type I bursts (4.8%), 12/63 Type II bursts (19.0%), 30/63 Type III bursts (47.6%), 8/63 Type IV bursts (12.7%) and 10/63 Type III/IV bursts (15.9%). We perform Monte Carlo simulations to constrain model parameters in order to reproduce the observations. We find that the favored value of the magnetic equipartition parameter in the forward shock ($\epsilon_B^f$) ranges from $10^{-6}$ to $10^{-2}$, and the reverse-to-forward ratio of $\epsilon_B$ ($R_B$) is about 100. The preferred electron equipartition parameter $\epsilon_e^{r,f}$ value is 0.01, which is smaller than the commonly assumed value, e.g., 0.1. This could mitigate the so- called "efficiency problem" for the internal shock model, if $\epsilon_e$ during the prompt emission phase (in the internal shocks) is large (say, $\sim 0.1$). The preferred $R_B$ value is in agreement with the results in previous works that indicates a moderately magnetized baryonic jet for GRBs.
Dark Energy, $H_0$ and Weak Gravity Conjecture

We point out that the physics at the extreme IR — cosmology — might provide tests of the physics of the extreme UV — the Weak Gravity Conjecture. The current discrepancies in the determination of H0 may hint at a modification of ΛCDM. An extension which may fit better comprises an early contribution to dark energy which “decays” into relativistic matter. On the other hand, the discourse on WGC to date suggests that fields which support cosmic acceleration may produce relativistic matter after they traverse a ∼ Planckian distance in field space. We explain how this offers a simple realization of the requisite cosmic phenomenology. Thus, if the resolution of H0 discrepancies is really early dark energy that ends with a shower of relativistic matter and the current ideas on WGC are indicative, this may be a rare opportunity to link the two extreme limits of quantum field theory.
Entanglement growth after a global quench in free scalar field theory

We compute the entanglement and Renyi entropy growth after a global quench in various dimensions in free scalar field theory. We study two types of quenches: a boundary state quench and a global mass quench. Both of these quenches are investigated for a strip geometry in 1, 2, and 3 spatial dimensions, and for a spherical geometry in 2 and 3 spatial dimensions. We compare the numerical results for massless free scalars in these geometries with the predictions of the analytical quasiparticle model based on EPR pairs, and find excellent agreement in the limit of large region sizes. At subleading order in the region size, we observe an anomalous logarithmic growth of entanglement coming from the zero mode of the scalar.
Uniform Silicon Isotope Ratios Across the Milky Way Galaxy

Author(s): Monson, Nathaniel N; Morris, Mark R; Young, Edward D | Abstract: We report the relative abundances of the three stable isotopes of silicon, $^{28}$Si, $^{29}$Si and $^{30}$Si, across the Galaxy using the $v = 0, J = 1 \to 0$ transition of silicon monoxide. The chosen sources represent a range in Galactocentric radii ($R_{\rm GC}$) from 0 to 9.8 kpc. The high spectral resolution and sensitivity afforded by the GBT permit isotope ratios to be corrected for optical depths. The optical-depth-corrected data indicate that the secondary-to-primary silicon isotope ratios $^{29}{\rm Si}/^{28}{\rm Si}$ and $^{30}{\rm Si}/^{28}{\rm Si}$ vary much less than predicted on the basis of other stable isotope ratio gradients across the Galaxy. Indeed, there is no detectable variation in Si isotope ratios with $R_{\rm GC}$. This lack of an isotope ratio gradient stands in stark contrast to the monotonically decreasing trend with $R_{\rm GC}$ exhibited by published secondary-to-primary oxygen isotope ratios. These results, when considered in the context of the expectations for chemical evolution, suggest that the reported oxygen isotope ratio trends, and perhaps that for carbon as well, require further investigation. The methods developed in this study for SiO isotopologue ratio measurements are equally applicable to Galactic oxygen, carbon and nitrogen isotope ratio measurements, and should prove useful for future observations of these isotope systems.
Decay Estimates for the One-dimensional Wave Equation with an Inverse Power Potential

We study the wave equation on the real line with a potential that falls off like vertical bar x vertical bar(-alpha) for vertical bar x vertical bar -> infinity where 2 infinity provided that there are no resonances at zero energy and no bound states. As an application, we consider the l = 0 Price Law for Schwarzschild black holes. This paper is part of our investigations into decay of linear waves on a Schwarzschild background, see [5, 6].