cssi/SciSciGPT-SciSciNet huggingface dataset:
Interacting edge states of fermionic symmetry-protected topological phases in two dimensions

Recently, it has been found that there exist symmetry-protected topological phases of fermions, which have no realizations in non-interacting fermionic systems or bosonic models. We study the edge states of such an intrinsically interacting fermionic SPT phase in two spatial dimensions, protected by $\mathbb{Z}_4\times\mathbb{Z}_2^T$ symmetry. We model the edge Hilbert space by replacing the internal $\mathbb{Z}_4$ symmetry with a spatial translation symmetry, and design an exactly solvable Hamiltonian for the edge model. We show that at low-energy the edge can be described by a two-component Luttinger liquid, with nontrivial symmetry transformations that can only be realized in strongly interacting systems. We further demonstrate the symmetry-protected gaplessness under various perturbations, and the bulk-edge correspondence in the theory.
On Transversally Elliptic Operators and the Quantization of Manifolds with f-Structure

Given an f-structure \({\varphi}\) on a manifold M, together with a compatible metric g and connection \({\nabla}\) on M, we construct an odd firstorder differential operator D whose principal symbol is of the type considered in [13]. In the special case of a CR-integrable almost \({\mathcal {S}}\) -structure, we show that when \({\nabla}\) is the generalized Tanaka-Webster connection of Lotta and Pastore, the operator D is given by D = \({{\sqrt {2} (\overline {\partial}_b + \overline{\partial}_{b}^{\ast})}}\), where \({\overline {\partial}_b}\) is the tangential Cauchy-Riemann operator.
The complexity of topological conjugacy of pointed Cantor minimal systems

In this paper, we analyze the complexity of topological conjugacy of pointed Cantor minimal systems from the point of view of descriptive set theory. We prove that the topological conjugacy relation on pointed Cantor minimal systems is Borel bireducible with the Borel equivalence relation $$\varDelta _{\mathbb {R}}^+$$ΔR+ on $$\mathbb {R}^{{\mathbb {N}}}$$RN defined by $$x \varDelta _{\mathbb {R}}^+y \Leftrightarrow \{x_i{:}\,i \in {\mathbb {N}}\}=\{y_i{:}\,i \in {\mathbb {N}}\}$$xΔR+yź{xi:iźN}={yi:iźN}. Moreover, we show that $$\varDelta _{\mathbb {R}}^+$$ΔR+ is a lower bound for the Borel complexity of topological conjugacy of Cantor minimal systems. Finally, we interpret our results in terms of properly ordered Bratteli diagrams and discuss some applications.
Debye mass in de Sitter space

We calculate the one-loop contributions to the polarization operator for scalar quantum electrodynamics in different external electromagnetic and gravitational fields. In the case of gravity, de Sitter space and its different patches were considered. It is shown that the Debye mass appears only in the case of alpha-vacuum in the Expanding Poincare Patch. It can be shown either by direct computations or by using analytical and causal properties of the de Sitter space. Also, the case of constant electric field is considered and the Debye mass is calculated.
Deriving Potential Coronal Magnetic Fields from Vector Magnetograms

The minimum-energy configuration for the magnetic field above the solar photosphere is curl-free (hence, by Ampere’s law, also current-free), so can be represented as the gradient of a scalar potential. Since magnetic fields are divergence free, this scalar potential obeys Laplace’s equation, given an appropriate boundary condition (BC). With measurements of the full magnetic vector at the photosphere, it is possible to employ either Neumann or Dirichlet BCs there. Historically, the Neumann BC was used with available line-of-sight magnetic field measurements, which approximate the radial field needed for the Neumann BC. Since each BC fully determines the 3D vector magnetic field, either choice will, in general, be inconsistent with some aspect of the observed field on the boundary, due to the presence of both currents and noise in the observed field. We present a method to combine solutions from both Dirichlet and Neumann BCs to determine a hybrid, “least-squares” potential field, which minimizes the integrated square of the residual between the potential and actual fields. We also explore weighting the residuals in the fit by spatially uniform measurement uncertainties. This has advantages both in not overfitting the radial field used for the Neumann BC, and in maximizing consistency with the observations. We demonstrate our methods with SDO/HMI vector magnetic field observations of active region 11158, and find that residual discrepancies between the observed and potential fields are significant, and they are consistent with nonzero horizontal photospheric currents. We also analyze potential fields for two other active regions observed with two different vector magnetographs, and find that hybrid-potential fields have significantly less energy than the Neumann fields in every case – by more than $10^{32}~\mbox{erg}$ in some cases. This has major implications for estimates of free magnetic energy in coronal field models, e.g., non-linear force-free field extrapolations.
DIAGNOSING THE TIME DEPENDENCE OF ACTIVE REGION CORE HEATING FROM THE EMISSION MEASURE. II. NANOFLARE TRAINS

The time dependence of heating in solar active regions can be studied by analyzing the slope of the emission measure distribution coolward of the peak. In a previous study we showed that low-frequency heating can account for 0% to 77% of active region core emission measures. We now turn our attention to heating by a finite succession of impulsive events for which the timescale between events on a single magnetic strand is shorter than the cooling timescale. We refer to this scenario as a 'nanoflare train' and explore a parameter space of heating and coronal loop properties with a hydrodynamic model. Our conclusions are (1) nanoflare trains are consistent with 86% to 100% of observed active region cores when uncertainties in the atomic data are properly accounted for; (2) steeper slopes are found for larger values of the ratio of the train duration {Delta} {sub H} to the post-train cooling and draining timescale {Delta} {sub C}, where {Delta} {sub H} depends on the number of heating events, the event duration and the time interval between successive events ({tau} {sub C}); (3) {tau} {sub C} may be diagnosed from the width of the hot component of the emission measure provided thatmore » the temperature bins are much smaller than 0.1 dex; (4) the slope of the emission measure alone is not sufficient to provide information about any timescale associated with heating-the length and density of the heated structure must be measured for {Delta} {sub H} to be uniquely extracted from the ratio {Delta} {sub H}/{Delta} {sub C}.« less
Contextuality Analysis of Impossible Figures

This paper has two purposes. One is to demonstrate contextuality analysis of systems of epistemic random variables. The other is to evaluate the performance of a new, hierarchical version of the measure of (non)contextuality introduced in earlier publications. As objects of analysis we use impossible figures of the kind created by the Penroses and Escher. We make no assumptions as to how an impossible figure is perceived, taking it instead as a fixed physical object allowing one of several deterministic descriptions. Systems of epistemic random variables are obtained by probabilistically mixing these deterministic systems. This probabilistic mixture reflects our uncertainty or lack of knowledge rather than random variability in the frequentist sense.
STUDY OF EXCITED NUCLEONS AND THEIR STRUCTURE

Recent advances in the study of excited nucleons are discussed. Much of the progress has been achieved due to the availability of high precision meson production data in the photoproduction and electroproduction sectors, the development of multi-channel partial wave analysis techniques, and advances in Lattice QCD with predictions of the full excitation spectrum.
WIDESPREAD PRESENCE OF SHALLOW CUSPS IN THE SURFACE-BRIGHTNESS PROFILE OF GLOBULAR CLUSTERS

Surface-brightness profiles of globular clusters with shallow central cusps (Σ ~ R ν with –0.3 ν –0.05) have been associated by several recent studies with the presence of a central intermediate-mass black hole (IMBH). Such shallow slopes are observed in several globular clusters thanks to the high angular resolution of Hubble Space Telescope (HST) imaging. In this Letter, we evaluate whether shallow cusps are a unique signature of a central IMBH by analyzing a sample of direct N-body simulations of star clusters with and without a central IMBH. We "observe" the simulations as if they were HST images. Shallow cusps are common in our simulation sample: star clusters without an IMBH have ν –0.3 in the pre-core-collapse and core-collapse phases. Post-core-collapse clusters without an IMBH transition to steeper cusps, –0.7 ν –0.4, only if the primordial binary fraction is very small, f bin < 3%, and if there are few stellar-mass BHs remaining. Otherwise ν values overlap the range usually ascribed to the presence of an IMBH throughout the entire duration of the simulations. In addition, measuring ν is intrinsically prone to significant uncertainty, therefore typical measurement errors may lead to ν ≥ –0.3 even when ν –0.4. Overall our analysis shows that a shallow cusp is not an unequivocal signature of a central IMBH and casts serious doubts on the usefulness of measuring ν in the context of the hunt for IMBHs in globular clusters.
Magnetorotational Instability: Nonmodal Growth and the Relationship of Global Modes to the Shearing Box

We study magnetorotational instability (MRI) using nonmodal stability techniques. Despite the spectral instability of many forms of MRI, this proves to be a natural method of analysis that is well-suited to deal with the non-self-adjoint nature of the linear MRI equations. We find that the fastest growing linear MRI structures on both local and global domains can look very different from the eigenmodes, invariably resembling waves shearing with the background flow (shear waves). In addition, such structures can grow many times faster than the least stable eigenmode over long time periods, and be localized in a completely different region of space. These ideas lead—for both axisymmetric and non-axisymmetric modes—to a natural connection between the global MRI and the local shearing box approximation. By illustrating that the fastest growing global structure is well described by the ordinary differential equations (ODEs) governing a single shear wave, we find that the shearing box is a very sensible approximation for the linear MRI, contrary to many previous claims. Since the shear wave ODEs are most naturally understood using nonmodal analysis techniques, we conclude by analyzing local MRI growth over finite timescales using these methods. The strong growth over a wide range of wave-numbers suggestsmore » that nonmodal linear physics could be of fundamental importance in MRI turbulence.« less
An Integral Condition for Core-Collapse Supernova Explosions

We derive an integral condition for core-collapse supernova (CCSN) explosions and use it to construct a new diagnostic of explodability. The fundamental challenge in CCSN theory is to explain how a stalled accretion shock revives to explode a star. In this manuscript, we assume that the shock revival is initiated by the delayed-neutrino mechanism and derive an integral condition for spherically symmetric shock expansion, $v_s > 0$. One of the most useful one-dimensional explosion conditions is the neutrino luminosity and mass-accretion rate ($L_{\nu}-\dot{\mathcal{M}}$) critical curve. Below this curve, steady-state stalled solutions exist, but above this curve, there are no stalled solutions. Burrows & Goshy suggested that the solutions above this curve are dynamic and explosive. In this manuscript, we take one step closer to proving this supposition; we show that all steady solutions above this curve have $v_s > 0$. Assuming that these steady $v_s > 0$ solutions correspond to explosion, we present a new dimensionless integral condition for explosion, $\Psi > 0$. $\Psi$ roughly describes the balance between pressure and gravity, and we show that this parameter is equivalent to the $\tau$ condition used to infer the $L_{\nu}-\dot{\mathcal{M}}$ critical curve. The illuminating difference is that there is a direct relationship between $\Psi$ and $v_s$. Below the critical curve, $\Psi$ may be negative, positive, and zero, which corresponds to receding, expanding, and stalled-shock solutions. At the critical curve, the minimum $\Psi$ solution is zero; above the critical curve, $\Psi_{\rm min} > 0$, and all steady solutions have $v_s > 0$. Using one-dimensional simulations, we confirm our primary assumptions and verify that $\Psi_{\rm min} > 0$ is a reliable and accurate explosion diagnostic.
A divergence‐conforming hybridized discontinuous Galerkin method for the incompressible Reynolds‐averaged Navier‐Stokes equations

We introduce a hybridized discontinuous Galerkin method for the incompressible Reynolds Averaged Navier-Stokes equations coupled with the Spalart-Allmaras one equation turbulence model. With a special choice of velocity and pressure spaces for both element and trace degrees of freedom, we arrive at a method which returns point-wise divergence-free mean velocity fields and properly balances momentum and energy. We further examine the use of different polynomial degrees and meshes to see how the order of the scalar eddy viscosity affects the convergence of the mean velocity and pressure fields, specifically for the method of manufactured solutions. As is standard with hybridized discontinuous Galerkin methods, static condensation can be employed to remove the element degrees of freedom and thus dramatically reduce the global number of degrees of freedom. Numerical results illustrate the effectiveness of the proposed methodology.
Ultrathin oxide films by atomic layer deposition on graphene.

In this paper, a method is presented to create and characterize mechanically robust, free-standing, ultrathin, oxide films with controlled, nanometer-scale thickness using atomic layer deposition (ALD) on graphene. Aluminum oxide films were deposited onto suspended graphene membranes using ALD. Subsequent etching of the graphene left pure aluminum oxide films only a few atoms in thickness. A pressurized blister test was used to determine that these ultrathin films have a Young’s modulus of 154 ± 13 GPa. This Young’s modulus is comparable to much thicker alumina ALD films. This behavior indicates that these ultrathin two-dimensional films have excellent mechanical integrity. The films are also impermeable to standard gases suggesting they are pinhole-free. These continuous ultrathin films are expected to enable new applications in fields such as thin film coatings, membranes, and flexible electronics.
Big Green at WNUT 2020 Shared Task-1: Relation Extraction as Contextualized Sequence Classification

Relation and event extraction is an important task in natural language processing. We introduce a system which uses contextualized knowledge graph completion to classify relations and events between known entities in a noisy text environment. We report results which show that our system is able to effectively extract relations and events from a dataset of wet lab protocols.
Dissipative-regime measurements as a tool for confirming and characterizing near-room-temperature superconductivity

The search for new superconducting materials approaching room-temperature benefits from having a variety of testing methodologies to confirm and characterize the presence of superconductivity. Often, the first signatures of new superconducting species occur incompletely and in very small volume fractions. These trace amounts may be too weak to produce an observable Meissner effect and the resistance may not go completely to zero if the percolation threshold is not met. Under these conditions, secondary behavior—such as transitions or cross overs in the temperature dependence of magnetoresistance, magnetic irreversibility, or thermopower—are often used as indications for the presence of superconductivity. Our group has developed a rather unique set of fast-timescale and dissipative transport measurements that can provide another tool set for confirming and characterizing suspected superconductivity. Here, we provide some background for these methods and elucidate their collaborative value in the search for new superconducting materials.
Comment: Struggles with Survey Weighting and Regression Modeling

We congratulate the author on an informative andthought-provoking discussion on a topic of broadinterest to the statistics community: the ﬁtting ofmodels to data collected through complex surveys.The number of papers written on this topic, whetherfrom a model-based or design-based perspective, issubstantial and goes back at least to Konijn (1962).This topic has led to some disagreements betweenthose advocating that the design best be ignoredwhen the primary interest is on the characteristics ofthe model, and those stating that the design cannotbe ignored. More recently, both sides of this discus-sion have moved to something approaching a con-sensus, with those favoring a model-based approachacknowledging the need to account for nonignorabledesigns in the model ﬁtting, while the traditionaldesign-based view has been extended to explore cer-tain circumstances under which it is appropriate toignore the design.Thecurrentarticle isan excellent example of thoserecent discussions of why the design needs to be ac-counted for in modeling, and how this can be donein practice. The importance of
Non-adiabatic Dynamics in d + id-Wave Fermionic Superfluids

We consider a problem of non-adiabatic dynamics of a 2D fermionic system with d + id-wave symmetry of pairing amplitude. Under the mean-field approximation, we determine the asymptotic behavior of the pairing amplitude following a sudden change of coupling strength. We also study an extended d + id pairing system for which the long-time asymptotic states of the pairing amplitude in the collisionless regime can be determined exactly. By using numerical methods, we have identified three non-equilibrium steady states described by different long-time asymptotes of the pairing amplitude for both the non-integrable and the integrable versions of d + id-wave models. We found that despite of its lack of integrability, long-time dynamics resulting from pairing quenches in the non-integrable d + id model are essentially similar to the ones found for its exactly integrable extended d + id model. We also obtain the long-time phase diagram of the extended d + id model through the Lax construction that exploits underlying integrability showing that the dynamic phases obtained by numerics are consistent with the dynamics of the exactly integrable approach. Both models describe a topological fermionic system with a topologically non-trivial BCS phase appearing at weak coupling strength. We show that the presence of oscillating order parameter region in the chiral d + id pairing dynamics differs from the d-wave ($d_{x^{2}-y^{2}}$), which may be used to probe pairing symmetries of chiral superconductors.
Stellar Kinematics of Young Clusters in Turbulent Hydrodynamic Simulations

The kinematics of newly formed star clusters are interesting both as a probe of the state of the gas clouds from which the stars form, and because they influence planet formation, stellar mass segregation, cluster disruption, and other processes controlled in part by dynamical interactions in young clusters. However, to date there have been no attempts to use simulations of star cluster formation to investigate how the kinematics of young stars change in response to variations in the properties of their parent molecular clouds. In this Letter, we report the results of turbulent self-gravitating simulations of cluster formation in which we consider both clouds in virial balance and those undergoing global collapse. We find that stars in these simulations generally have velocity dispersions smaller than that of the gas by a factor of ~5, independent of the dynamical state of the parent cloud, so that subvirial stellar velocity dispersions arise naturally even in virialized molecular clouds. The simulated clusters also show large-scale stellar velocity gradients of ~0.2-2 km s–1 pc–1 and strong correlations between the centroid velocities of stars and gas, both of which are observed in young clusters. We conclude that star clusters should display subvirial velocity dispersions, large-scale velocity gradients, and strong gas-star velocity correlations regardless of whether their parent clouds are in virial balance, and, conversely, that observations of these features cannot be used to infer the dynamical state of the parent gas clouds.
What makes a research article newsworthy

There has been tremendous growth in the amount of scientific literature being published every year. Yet, very little of it receives press coverage. Mentions by news outlets often establish the relevance the research has to society in general. In the present study, we focused on better understanding the factors that contribute to a research article's newsworthiness. We have built three classifiers to predict the likelihood of research article receiving online press coverage, based on features that quantify the attention it has received on various online platforms. The Random Forest classifier performed best with an accuracy rate of 0.92.
Large collaboration in observational astronomy: the Gemini Planet Imager exoplanet survey case

The Gemini Planet Imager (GPI) is a next-generation high-contrast imager built for the Gemini Observatory. The GPI exoplanet survey (GPIES) consortium is made up of 102 researchers from ~28 institutions in North and South America and Europe. In November 2014, we launched a search for young Jovian planets and debris disks. In this paper, we discuss how we have coordinated the work done by this large team to improve the technical and scientific productivity of the campaign, and describe lessons we have learned that could be useful for future instrumentation-based astronomical surveys. The success of GPIES lies mostly on its decentralized structure, clear definition of policies that are signed by each member, and the heavy use of modern tools for communicating, exchanging information, and processing data.
Experimental broadband absorption enhancement in silicon nanohole structures with optimized complex unit cells

We design silicon membranes with nanohole structures with optimized complex unit cells that maximize broadband absorption. We fabricate the optimized design and measure the optical absorption. We demonstrate an experimental broadband absorption about 3.5 times higher than an equally-thick thin film.
Level-rank duality via tensor categories

We give a new way to derive branching rules for the conformal embedding $$(\hat{\mathfrak{sl}}_n)_m\oplus(\hat{\mathfrak{sl}}_m)_n\subset(\hat{\mathfrak{sl}}_{nm})_1. $$ In addition, we show that the category \({\mathcal{C}(\hat{\mathfrak{sl}}_n)_m^0}\) of degree zero integrable highest weight \({(\hat{\mathfrak{sl}}_n)_m}\) -representations is braided equivalent to \({\mathcal{C}(\hat{\mathfrak{sl}}_m)_n^0}\) with the reversed braiding.
Finding One Community in a Sparse Graph

We consider a random sparse graph with bounded average degree, in which a subset of vertices has higher connectivity than the background. In particular, the average degree inside this subset of vertices is larger than outside (but still bounded). Given a realization of such graph, we aim at identifying the hidden subset of vertices. This can be regarded as a model for the problem of finding a tightly knitted community in a social network, or a cluster in a relational dataset. In this paper we present two sets of contributions: (i) We use the cavity method from spin glass theory to derive an exact phase diagram for the reconstruction problem. In particular, as the difference in edge probability increases, the problem undergoes two phase transitions, a static phase transition and a dynamic one. (ii) We establish rigorous bounds on the dynamic phase transition and prove that, above a certain threshold, a local algorithm (belief propagation) correctly identify most of the hidden set. Below the same threshold no local algorithm can achieve this goal. However, in this regime the subset can be identified by exhaustive search. For small hidden sets and large average degree, the phase transition for local algorithms takes an intriguingly simple form. Local algorithms succeed with high probability for \(\deg _\mathrm{in} - \deg _\mathrm{out} > \sqrt{\deg _\mathrm{out}/e}\) and fail for \(\deg _\mathrm{in} - \deg _\mathrm{out} < \sqrt{\deg _\mathrm{out}/e}\) (with \(\deg _\mathrm{in}\), \(\deg _\mathrm{out}\) the average degrees inside and outside the community). We argue that spectral algorithms are also ineffective in the latter regime. It is an open problem whether any polynomial time algorithms might succeed for \(\deg _\mathrm{in} - \deg _\mathrm{out} < \sqrt{\deg _\mathrm{out}/e}\).
Chern classes and compatible power operations in inertial K-theory

Let X = [X∕G] be a smooth Deligne–Mumford quotient stack. In a previous paper we constructed a class of exotic products called inertial products on K(IX), the Grothendieck group of vector bundles on the inertia stack IX. In this paper we develop a theory of Chern classes and compatible power operations for inertial products. When G is diagonalizable these give rise to an augmented λ-ring structure on inertial K-theory. One well-known inertial product is the virtual product. Our results show that for toric Deligne–Mumford stacks there is a λ-ring structure on inertial K-theory. As an example, we compute the λ-ring structure on the virtual K-theory of the weighted projective lines ℙ(1,2) and ℙ(1,3). We prove that, after tensoring with ℂ, the augmentation completion of this λ-ring is isomorphic as a λ-ring to the classical K-theory of the crepant resolutions of singularities of the coarse moduli spaces of the cotangent bundles T∗ℙ(1,2) and T∗ℙ(1,3), respectively. We interpret this as a manifestation of mirror symmetry in the spirit of the hyper-Kahler resolution conjecture.
COVID-19 in Children: A Review and Parallels to Other Hyperinflammatory Syndromes

During the COVID-19 pandemic, children have had markedly different clinical presentations and outcomes compared to adults. In the acute phase of infection, younger children are relatively spared the severe consequences reported in adults. Yet, they are uniquely susceptible to the newly described Multisystem Inflammatory Syndrome in Children (MIS-C). This may result from the developmental "immunodeficiency" resulting from a Th2 polarization that starts in utero and is maintained for most of the first decade of life. MIS-C may be due to IgA complexes in a Th2 environment or a Th1-like response to COVID-19 antigens that developed slowly. Alternatively, MIS-C may occur in vulnerable hosts with genetic susceptibilities in other immune and non-immune pathways. Herein, we present a brief overview of the host immune response, virologic and genetic factors, and comparable inflammatory syndromes that may explain the pathophysiology leading to drastic differences in clinical presentation and outcomes of COVID-19 between children and adults.
Inferring the Dynamics of the State Evolution During Quantum Annealing

To solve an optimization problem using a commercial quantum annealer, one has to represent the problem of interest as an Ising or a quadratic unconstrained binary optimization (QUBO) problem and submit its coefficients to the annealer, which then returns a user-specified number of low-energy solutions. It would be useful to know what happens in the quantum processor during the anneal process so that one could design better algorithms or suggest improvements to the hardware. However, existing quantum annealers are not able to directly extract such information from the processor. Hence, in this article we propose to use advanced features of D-Wave 2000Q to indirectly infer information about the dynamics of the state evolution during the anneal process. Specifically, D-Wave 2000Q allows the user to customize the anneal schedule, that is, the schedule with which the anneal fraction is changed from the start to the end of the anneal. Using this feature, we design a set of modified anneal schedules whose outputs can be used to generate information about the states of the system at user-defined time points during a standard anneal. With this process, called slicing , we obtain approximate distributions of lowest-energy anneal solutions as the anneal time evolves. We use our technique to obtain a variety of insights into the annealer, such as the state evolution during annealing, when individual bits in an evolving solution flip during the anneal process and when they stabilize, and we introduce a technique to estimate the freeze-out point of both the system as well as of individual qubits.
Projective cases for the restriction of the oscillator representation to dual pairs of type I

For all the irreducible dual pairs of type I $(G,G')$, we analyze the restriction of the oscillator representation as a $(\mathfrak{g}', K')$-module, when $G'$ is the smaller group. For all $(G,G')$ in the stable range, as well as one more case, the modules obtained are projective. We use the duality correspondence introduced by Howe to analyze these restrictions.
Digital light processing in a hybrid atomic force microscope: In Situ, nanoscale characterization of the printing process

Abstract Stereolithography (SLA) and digital light processing (DLP) are powerful additive manufacturing techniques that address a wide range of applications including regenerative medicine, prototyping, and manufacturing. Unfortunately, these printing processes introduce micrometer-scale anisotropic inhomogeneities due to the resin absorptivity, diffusivity, reaction kinetics, and swelling during the requisite photoexposure. Previously, it has not been possible to characterize high-resolution mechanical heterogeneity as it develops during the printing process. By combining DLP 3D printing with atomic force microscopy in a hybrid instrument, heterogeneity of a single, in situ printed voxel is characterized. Here, we describe the instrument and demonstrate three modalities for characterizing voxels during and after printing. Sensing Modality I maps the mechanical properties of just-printed, resin-immersed voxels, providing the framework to study the relationships between voxel sizes, print exposure parameters, and voxel-voxel interactions. Modality II captures the nanometric, in situ working curve and is the first demonstration of in situ cure depth measurement. Modality III dynamically senses local rheological changes in the resin by monitoring the viscoelastic damping coefficient of the resin during patterning. Overall, this instrument equips researchers with a tool to develop rich insight into resin development, process optimization, and fundamental printing limits.
Decentralized Optimal Control in Multi-lane Merging for Connected and Automated Vehicles

We address the problem of optimally controlling Connected and Automated Vehicles (CAVs) arriving from two multi-lane roads and merging at multiple points where the objective is to jointly minimize the travel time and energy consumption of each CAV subject to speed-dependent safety constraints, as well as speed and acceleration constraints. This problem was solved in prior work for two single-lane roads. A direct extension to multi-lane roads is limited by the computational complexity required to obtain an explicit optimal control solution. Instead, we propose a general framework that converts a multi-lane merging problem into a decentralized optimal control problem for each CAV in a less-conservative way. To accomplish this, we employ a joint optimal control and barrier function method to efficiently get an optimal control for each CAV with guaranteed satisfaction of all constraints. Simulation examples are included to compare the performance of the proposed framework to a baseline provided by human-driven vehicles with results showing significant improvements in both time and energy metrics.
Formal methods approach to the charging facility location problem for battery electric vehicles

Battery electric vehicles (BEVs) are becoming more prevalent as improvements in battery technology and energy management continue to be made. As the number of electric vehicles grows, the demand for fast-charging stations is expected to increase dramatically. Thus, building new charging station infrastructure efficiently will be key to reducing upfront costs while meeting consumer demands. In this work, we propose a method for choosing a set of charging station locations that are optimized based on a set of given common vehicle demand points. As part of this solution, we also offer a novel abstraction of the road network on which energy-efficient paths that account for charge-time delays may be found. The current algorithm chooses the optimal charging locations for a single agent which has a route objective specified using temporal logic. To demonstrate the proposed method, the running example shows how a charging station could be chosen for an electric delivery vehicle. Simulations were run on sample road networks with a given set of demand points to service and potential charging station locations to compare. The method is shown to successfully rank potential charging stations in terms of their expected average charging time cost.
Towards Supporting Programming Education at Scale via Live Streaming

Live streaming, which allows streamers to broadcast their work to live viewers, is an emerging practice for teaching and learning computer programming. Participation in live streaming is growing rapidly, despite several apparent challenges, such as a general lack of training in pedagogy among streamers and scarce signals about a stream's characteristics (e.g., difficulty, style, and usefulness) to help viewers decide what to watch. To understand why people choose to participate in live streaming for teaching or learning programming, and how they cope with both apparent and non-obvious challenges, we interviewed 14 streamers and viewers about their experience with live streaming programming. Among other results, we found that the casual and impromptu nature of live streaming makes it easier to prepare than pre-recorded videos, and viewers have the opportunity to shape the content and learning experience via real-time communication with both the streamer and each other. Nonetheless, we identified several challenges that limit the potential of live streaming as a learning medium. For example, streamers voiced privacy and harassment concerns, and existing streaming platforms do not adequately support viewer-streamer interactions, adaptive learning, and discovery and selection of streaming content. Based on these findings, we suggest specialized tools to facilitate knowledge sharing among people teaching and learning computer programming online, and we offer design recommendations that promote a healthy, safe, and engaging learning environment.
The complete chloroplast genome sequence of American elm ( Ulmus americana ) and comparative genomics of related species

American elm, Ulmus americana L., was widely cultivated in the USA and Canada as a landscape tree. Despite its importance in landscaping and horticulture, its genome is poorly characterized. We assembled the chloroplast genomes of two American elm genotypes (RV16 and Am. 57845); to our knowledge, this is the first description of sequencing and assembly of this species. The complete chloroplast genome of U. americana ranged from 158,935 to 158,993 bp and it contains 127 genes, namely 85 protein-coding genes, 34 tRNA genes, and 8 rRNA genes. Between the two American elm chloroplasts we sequenced, we identified 240 high-quality sequence variants (SNPs and indels). To evaluate the phylogeny of American elm, we compared the chloroplast genomes of the two American elms with seven Asian elm species and twelve other chloroplast genomes available through the NCBI database. As expected, Ulmus was closely related to Morus and Cannabis, as all three genera are assigned to the Urticales. We clarified the timing of the divergence of American elm from the available Asian elms, the divergence within these Asian elms, and all the species’ relative ages. Comparison of the chloroplasts of American elm with the available Asian elms revealed that trnH was absent from American elm but not most Asian elms; conversely, petB, petD, psbL, trnK, and rps16 are present in the American elm but absent from all Asian elms analyzed. ycf15 was present in both American and Asian elms but absent from members of closely related genera. The complete chloroplast genome of U. americana will provide useful genetic resources for characterizing the genetic diversity of U. americana and potentially help to conserve natural populations of American elm.
Health Care For The Elderly: How Much? Who Will Pay For It?

Health care expenditures on the elderly tend to grow about 4 percent per year more rapidly than the gross domestic product (GDP). This could plunge the nation into a severe economic and social crisis within two decades. This paper describes recent growth in age/sex-specific health care utilization by the elderly and discusses the important role of technology in that growth. It also explores the potential for the elderly to pay for additional care through increases in work and savings. Efforts to "save Medicare" will prove to be "too little, too late" unless they are embedded in broader policy initiatives that slow the rate of growth of health care spending and/or increase the income of the elderly.
Evidence on the role of holding company acquisitions in the management of bank capital

This article addresses the issue of the impact of bank acquisitions on the capital positions of acquired banks. The hypothesis tested is that acquisition-related capital changes reflect divergent capital-related acquisition motives which induce significant infusion of capital into some acquired banks and significant withdrawals from others.
Framing, Probability Distortions, and Insurance Decisions

A series of studies examines whether certain biases in probability assessments and perceptions of loss, previously found in experimental studies, affect consumers’ decisions about insurance. Framing manipulations lead the consumers studied here to make hypothetical insurance-purchase choices that violate basic laws of probability and value. Subjects exhibit distortions in their perception of risk and framing effects in evaluating premiums and benefits. Illustrations from insurance markets suggest that the same effects occur when consumers make actual insurance purchases.
Organization Structure and Credibility: Evidence from Commercial Bank Securities Activities Before the Glass-Steagall Act

We examine the two ways in which US commercial banks organized their investment banking operations before the 1933 Glass-Steagall Act forced the banks to leave the securities business: as an internal securities department within the bank and as a separately incorporated affiliate with its own board of directors. While departments underwrote seemingly higher quality firms and securities than did comparable affiliates, the departments obtained lower prices for the issues they underwrote. The higher risk premium associated with the internal department is consistent with investors discounting for the greater likelihood of conflicts of interest when lending and underwriting are within the same structure. As a result, commercial banks evolved toward choosing the separate affiliate structure. Our results suggest that internal structure is an effective commitment mechanism, and absent other distortions, market pressures would propel banks to adopt an internal structure that would address regulators' concerns about conflicts of interest.
Safeguarding Democracy: Powersharing and Democratic Survival

Democracy is often fragile, especially in states recovering from civil conflict. To protect emerging democracies, many scholars and practitioners recommend political powersharing institutions, which aim to safeguard minority group interests. Yet there is little empirical research on whether powersharing promotes democratic survival, and some concern that it limits electoral accountability. To fill this gap, we differentiate between inclusive, dispersive, and constraining powersharing institutions and analyze their effects on democratic survival from 1975 to 2015 using a global dataset. We find sharp distinctions across types of powersharing and political context. Inclusive powersharing, such as ethnic quotas, promotes democratic survival only in post-conflict settings. In contrast, dispersive institutions such as federalism tend to destabilize post-conflict democracies. Only constraining powersharing consistently facilitates democratic survival regardless of recent conflict. Institution-builders and international organizations should therefore prioritize institutions that constrain leaders, including independent judiciaries, civilian control of the armed forces, and constitutional protections of individual and group rights.
Nonlinearity in the dynamics of financial markets

Abstract A new set of methodologies extracts key nonlinearities in the dynamics of financial markets from data that would appear to be completely random with ordinary linear time series methods. The understanding acquired from this analysis forms a basis for modeling conflicting and competing motivations in market decisions. By standardizing the daily changes using the mean and standard deviation, it then becomes possible to compare the quantitative impact of very different variables such as price trend and valuation, and the nonlinear relationship between them. The analysis of a large data set of closing stock prices provides strong statistical evidence that relative daily price change is positively influenced by valuation, recent price trend, short term volatility, volume trend and the M2 money supply. However, there is a strong nonlinearity in the influence of the price trend, so that a significantly large recent uptrend has a negative influence on the subsequent day’s relative price change. The nonlinearity is the key to understanding the conflicting role of price trend, since a single large data set exhibits both underreaction and overreaction in different regimes of the independent variables. The role of long term volatility is not a clear-cut risk/return inverse relation. But rather there is an ambiguous and complicated relationship between volatility and return. There is limited support for resistance when prices near the quarterly high. Mixed effects regressions are used after standardizing the data by subtracting the mean and dividing by one standard deviation individually for each of the 119 closed-end funds. A valuation variable is constructed in terms of the recent history of net asset value.
The relevance of the value-relevance literature for financial accounting standard setting $

In this paper we critically evaluate the standard-setting inferences that can be drawn from value relevance research studies that are motivated by standard setting. Our evaluation concentrates on the theories of accounting, standard setting and valuation that underlie those inferences. Unless those underlying theories are descriptive of accounting, standard setting and valuation, the value-relevance literature’s reported associations between accounting numbers and common equity valuations have limited implications or inferences for standard setting; they are mere associations. We argue that the underlying theories are not descriptive and hence drawing standard-setting inferences is difficult. r 2001 Elsevier Science B.V. All rights reserved. JEL classification: M41; M44; G12
Hayek's Rule, NGDP Targeting, and the Productivity Norm: Theory and Application

The 2008 crisis demonstrated that, absent inflationary pressures, significant economic stress can occur as a consequence of loose monetary policy. This scenario raises the question as to whether there is a better alternative to price stability as a guiding principle for monetary policy. In this paper, I explore the theoretical insights of the productivity norm, its superiority to price stability in the form of Hayek’s Rule and market monetarism’s NGDP Targeting as the focus of monetary policy, and the challenges of applying such principles by central banks.
Co-Creating Adoption Law: A Lutheran Perspective

: Lutheran theological insights on orders of creation, the duty of neighbor-love, and the pervasiveness of sin in institutions as well as individuals can help secular governments and adoption agencies consider how to respond to controversies over interracial and intercountry adoption, parental qualifications, open adoption, and the market structure of adoption in the United States.
Second-Order Benefits from Standards

This Article contributes to the new governance literature by analyzing how private parties proat from standards. Scholars previously have focused on what I call “arst-order” proats from the right to extract rent directly from the ownership or application of standards. But some parties also make “second-order” indirect proats by engaging in some new enterprise not directly related to the value of the relevant standard. For example, an accounting arm can offer lucrative consulting services based on its reputation as a standard bearer. Second-order proats are most substantial for strong form standards, which arise when the government designates a private entity as standard setter and assigns it the task of enforcement and regulation. This Article suggests that the question of whether such privatization is beneacial depends not only on arst-order rents, but also on second-order costs and beneats. It considers two examples from the anancial markets: over-the-counter derivatives and credit rating agencies.
International Trade and the Changing Demand for Skilled Workers in High-Tech Manufacturing

States and localities in the U.S. put considerable effort into attracting and maintaining high-tech manufacturing industries to preserve manufacturing employment. However, little work has examined whether high-tech industries respond differently than traditional manufacturing to changing trade pressures. This study investigates the impact of international trade on skilled and unskilled labor demand across manufacturing sectors. Results of this study indicate that changes in exchange rates and trade orientation have similar effects across high-tech and traditional manufacturing sectors. In addition, findings suggest that there is a high degree of variation in the trade-related effects on labor demand across individual high-tech sectors, and that the direction of these effects often runs counter to the predictions of traditional trade theory.
Climate change dilemma: technology, social change or both?: An examination of long-term transport policy choices in the United States

Time is fast running out for formulating a viable global climate policy regime even as it seems obvious that the major initiative will have to come from the United States, which currently appears indisposed to take any meaningful action at all. This paper reviews the prospects for emissions reductions in the US passenger transport sector and the technical, economic, social, and political barriers to developing policies that focus solely on technology or pricing. Using scenarios it shows that, in order to meet stringent emissions targets over the coming half-century, technology and pricing policies may have to be supplemented by strategies to change life-styles and land uses in ways that effectively reduce car dependence. In the medium to long term, bold initiatives that treat vehicle users as citizens capable of shifting their interests and behaviour could form kernels of social change that in turn provide opportunities for removing many of the social and political constraints.