cssi/SciSciGPT-SciSciNet huggingface dataset:
5 – Rational Exponents and Roots

Publisher Summary Many of the formulas that describe the characteristics of objects in the universe involve roots. When dealing with negative numbers and radicals, the only restriction concerns negative numbers under even roots. One can have negative signs in front of radicals and negative numbers under odd roots and still obtain real numbers. This chapter discusses multiplication, division, factoring, and simplification of some expressions that resemble polynomials but contain rational exponents. Multiplication of expressions that contain radicals is similar to multiplication of polynomials. A radical expression is said to be in simplified form: (1) if there is no factor of the radicand that can be written as a power greater than or equal to the index; (2) if there are no fractions under the radical sign; and (3) if there are no radicals in the denominator. Radical expressions are added and subtracted by using the distributive property to combine similar radicals. Similar radicals are the radicals with the same index and the same radicand. Radical expressions are multiplied in the same way as the polynomials.
A MATCHING MODEL WITH ENDOGENOUS SKILL REQUIREMENTS

We consider a labor market in which workers differ in their abilities and jobs differ in their skill requirements. The distribution of worker abilities is exogenous, but we model the choice of skill requirements by firms. High-skill jobs produce more output than low-skill jobs, but high-skill jobs require high-skill workers and thus are more difficult to fill. We use a matching model together with a Nash bargaining approach to wage setting to determine the equilibrium mix of job types, along with the equilibrium relationship between worker and job characteristics, wages, and unemployment.
On the security margin of MAC striping.

MAC striping has been suggested as a technique to authenticate encrypted payloads using short tags. For an idealized MAC scheme, the probability of a selective forgery has been estimated as ( `+m m )−1 ·2−m, when utilizing MAC striping with `-bit payloads and m-bit tags. We show that this estimate is too optimistic. For m ≤ ` and any payload, we achieve a selective forgery with probability ≥ ( `+m m )−1 , and usually many orders of magnitude more than that.
Microtubule assembly and pole coalescence: early steps in C. elegans oocyte meiosis I spindle assembly.

How oocytes assemble bipolar meiotic spindles in the absence of centrosomes as microtubule organizing centers remains poorly understood. We have used live cell imaging in C. elegans to investigate requirements for the nuclear lamina and for conserved regulators of microtubule dynamics during oocyte meiosis I spindle assembly, assessing these requirements with respect to recently identified spindle assembly steps. We show that the nuclear lamina is required for microtubule bundles to form a peripheral cage-like structure that appears shortly after oocyte nuclear envelope breakdown and surrounds the oocyte chromosomes, although bipolar spindles still assembled in its absence. Although two conserved regulators of microtubule nucleation, RAN-1 and γ-tubulin, are not required for bipolar spindle assembly, both contribute to normal levels of spindle-associated microtubules and spindle assembly dynamics. Finally, the XMAP215 ortholog ZYG-9 and the nearly identical minus-end directed kinesins KLP-15/16 are required for proper assembly of the early cage-like structure of microtubule bundles, and for early spindle pole foci to coalesce into a bipolar structure. Our results provide a framework for assigning molecular mechanisms to recently described steps in C. elegans oocyte meiosis I spindle assembly.
Vertex-faithful regular polyhedra

Abstract We study the abstract regular polyhedra with automorphism groups that act faithfully on their vertices, and show that each non-flat abstract regular polyhedron covers a “vertex-faithful” polyhedron with the same number of vertices. We then use this result and earlier work on flat polyhedra to study abstract regular polyhedra based on the size of their vertex set. In particular, we classify all regular polyhedra where the number of vertices is prime or twice a prime. We also construct the smallest regular polyhedra with a prime squared number of vertices.
DualSDF: Semantic Shape Manipulation Using a Two-Level Representation

We are seeing a Cambrian explosion of 3D shape representations for use in machine learning. Some representations seek high expressive power in capturing high-resolution detail. Other approaches seek to represent shapes as compositions of simple parts, which are intuitive for people to understand and easy to edit and manipulate. However, it is difficult to achieve both fidelity and interpretability in the same representation. We propose DualSDF, a representation expressing shapes at two levels of granularity, one capturing fine details and the other representing an abstracted proxy shape using simple and semantically consistent shape primitives. To achieve a tight coupling between the two representations, we use a variational objective over a shared latent space. Our two-level model gives rise to a new shape manipulation technique in which a user can interactively manipulate the coarse proxy shape and see the changes instantly mirrored in the high-resolution shape. Moreover, our model actively augments and guides the manipulation towards producing semantically meaningful shapes, making complex manipulations possible with minimal user input.
Attributes of a Profession

The professions occupy a position of great surgeon, and teacher.4 What common attri importance on the American scene.1 In a butes do these professional occupations pos society such as ours, characterized by misess which distinguish them from the non nute division of labor based upon technical professional ones? After a careful canvass specialization, many important features of of the sociological literature on occupa social organization are dependent upon tions, this writer has been able to distill professional functions. Professional activfive elements, upon which there appears to ity is coming to play a predominant role be consensus among the students of the in the life patterns of increasing numbers subject, as constituting the distinguishing of individuals of both sexes, occupying attributes of a profession.5 Succinctly put, much of their waking moments, providing all professions seem to possess: (1) systematic life goals, determining behavior, and shaptheory, (2) authority, (3) community sanc ing personality. It is no wonder, therefore, tion, (4) ethical codes, and (5) a culture, that the phenomenon of professionalism The purpose of this article is to describe has become an object of observation by fully these attributes. sociologists.2 The sociological approach to Before launching into our description, a professionalism is one that views a profespreliminary word of caution is due. With sion as an organized group which is conrespect to each of the above attributes, the stantly interacting with the society that forms its matrix, which performs its social 1 Talcott Parsons. "The Professions and Social functions through a network of formal and Structure," Social Forces, Vol. 17 (May 1939), pp. informal relationships, and which creates y „ , „ . , . T„ . , , r . . ,. 2 Theodore Caplow, The Sociology of Work Its own subculture requiring adjustments (Minneapolis: University of Minnesota Press, 1954). to it as a prerequisite for career success.3 3 Oswald Hall, "The Stages of a Medical Career," Within the professional category of its American Journal of Sociology, Vol. 53 (March occupational classification the United States 1948) of California, Berkeley, who, as members of his i jornia. Berkeley. The writer ts indebted to Dr. , . , , . ., . , ' 7 research seminars, assisted him in identifying and William A. Kornhauser, Sociology Department of abstracting the sociological literature on occupa the university, for his constructive criticisms during tions. Their conscientious assistance made possible the preparation of this paper. the formulation presented in this paper.
Evaluating complexity and resilience trade-offs in emerging memory inference machines

Neuromorphic-style inference only works well if limited hardware resources are maximized properly, e.g. accuracy continues to scale with parameters and complexity in the face of potential disturbance. In this work, we use realistic crossbar simulations to highlight that compact implementations of deep neural networks are unexpectedly susceptibilie to collapse from multiple system disturbances. Our work proposes a middle path towards high performance and strong resilience utilizing the Mosaics framework, and specifically by re-using synaptic connections in a recurrent neural network implementation that possesses a natural form of noise-immunity.
NLP Scholar: An Interactive Visual Explorer for Natural Language Processing Literature

As part of the NLP Scholar project, we created a single unified dataset of NLP papers and their meta-information (including citation numbers), by extracting and aligning information from the ACL Anthology and Google Scholar. In this paper, we describe several interconnected interactive visualizations (dashboards) that present various aspects of the data. Clicking on an item within a visualization or entering query terms in the search boxes filters the data in all visualizations in the dashboard. This allows users to search for papers in the area of their interest, published within specific time periods, published by specified authors, etc. The interactive visualizations presented here, and the associated dataset of papers mapped to citations, have additional uses as well including understanding how the field is growing (both overall and across sub-areas), as well as quantifying the impact of different types of papers on subsequent publications.
Rationally inattentive intertemporal choice

Discounting of future rewards is traditionally interpreted as evidence for an intrinsic preference in favor of sooner rewards. However, temporal discounting can also arise from internal uncertainty in value representations of future events, if one assumes that noisy mental simulations of the future are rationally combined with prior beliefs. Here, we further develop this idea by considering how simulation noise may be adaptively modulated by task demands, based on principles of rational inattention. We show how the optimal allocation of mental effort can give rise to the magnitude effect in intertemporal choice. In a re-analysis of two prior data sets, and in another experiment, we reveal several behavioral signatures of this theoretical account, tying choice stochasticity to the magnitude effect. We conclude that some aspects of temporal discounting may result from a cognitively plausible adaptive response to the costs of information processing.
Random bipartite posets and extremal problems

Previously, Erdős, Kierstead and Trotter [5] investigated the dimension of random height 2 partially ordered sets. Their research was motivated primarily by two goals: (1) analyzing the relative tightness of the Furedi–Kahn upper bounds on dimension in terms of maximum degree; and (2) developing machinery for estimating the expected dimension of a random labeled poset on n points. For these reasons, most of their effort was focused on the case $$0<p\le 1/2$$ . While bounds were given for the range $$1/2\le p <1$$ , the relative accuracy of the results in the original paper deteriorated as p approaches 1. Motivated by two extremal problems involving conditions that force a poset to contain a large standard example, we were compelled to revisit this subject, but now with primary emphasis on the range $$1/2\le p<1$$ . Our sharpened analysis shows that as p approaches 1, the expected value of dimension increases and then decreases, answering in the negative a question posed in the original paper. Along the way, we apply inequalities of Talagrand and Janson, establish connections with latin rectangles and the Euler product function, and make progress on both extremal problems.
Integrating XMALab and DeepLabCut for high-throughput XROMM.

Marker tracking is a major bottleneck in studies involving X-ray Reconstruction of Moving Morphology (XROMM). Here, we tested whether DeepLabCut, a new deep learning package built for markerless tracking, could be applied to videoradiographic data to improve data processing throughput. Our novel workflow integrates XMALab, the existing XROMM marker tracking software, and DeepLabCut while retaining each program's utility. XMALab is used for generating training datasets, error correction, and 3D reconstruction, whereas the majority of marker tracking is transferred to DeepLabCut for automatic batch processing. In the two case studies that involved an in vivo behavior, our workflow achieved a 6 to 13-fold increase in data throughput. In the third case study, which involved an acyclic, post mortem manipulation, DeepLabCut struggled to generalize to the range of novel poses and did not surpass the throughput of XMALab alone. Deployed in the proper context, this new workflow facilitates large scale XROMM studies that were previously precluded by software constraints.
The Convex Geometry of Integrator Reach Sets.

We study the convex geometry of the forward reach sets for integrator dynamics in finite dimensions with bounded control. We derive closed-form expressions for the volume and the diameter (i.e., maximal width) of these sets in terms of the state space dimension, control bound, and time. These results are novel, and use convex analysis to give an analytical handle on the "size" of the integrator reach set. Several examples are provided to illustrate our results. We envision that the ideas presented here will motivate further theoretical and algorithmic development in reach set computation.
Robust Performance Guarantees for System Level Synthesis.

We generalize the system level synthesis framework to systems defined by bounded causal linear operators, and use this parameterization to make connections between robust system level synthesis and classical results from the robust control literature. In particular, by leveraging results from L1 robust control, we show that necessary and sufficient conditions for robust performance with respect to causal bounded linear uncertainty in the system dynamics can be translated into convex constraints on the system responses. We exploit this connection to show that these conditions naturally allow for the incorporation of delay, sparsity, and locality constraints on the system responses and resulting controller implementation, allowing these methods to be applied to large-scale distributed control problems -- to the best of our knowledge, these are the first such robust performance guarantees for distributed control systems.
The consequences of limiting shareholder litigation: Evidence from exclusive forum provisions

Abstract In response to an explosion of shareholder litigation, many firms have adopted exclusive forum provisions which limit lawsuits to courts in a firm's state of incorporation. This paper examines the consequences of a required venue for shareholder litigation. Delaware-incorporated companies experience significant increases in firm value around exogenous events that confirmed the use of a specified forum. Reduced legal costs and the designation of the domicile court as the sole forum to hear shareholder claims contribute to the increase in firm value. Overall, these findings suggest that a required venue for shareholder litigation benefits firms by eliminating multi-jurisdictional lawsuits and reducing the threat of claims with little merit.
Graph neural network based coarse-grained mapping prediction

The selection of coarse-grained (CG) mapping operators is a critical step for CG molecular dynamics (MD) simulation. It is still an open question about what is optimal for this choice and there is a need for theory. The current state-of-the art method is mapping operators manually selected by experts. In this work, we demonstrate an automated approach by viewing this problem as supervised learning where we seek to reproduce the mapping operators produced by experts. We present a graph neural network based CG mapping predictor called Deep Supervised Graph Partitioning Model (DSGPM) that treats mapping operators as a graph segmentation problem. DSGPM is trained on a novel dataset, Human-annotated Mappings (HAM), consisting of 1180 molecules with expert annotated mapping operators. HAM can be used to facilitate further research in this area. Our model uses a novel metric learning objective to produce high-quality atomic features that are used in spectral clustering. The results show that the DSGPM outperforms state-of-the-art methods in the field of graph segmentation. Finally, we find that predicted CG mapping operators indeed result in good CG MD models when used in simulation.
138175 (2000 EE104) and the Source of Interplanetary Field Enhancements

We present the first optical observations taken to characterize the near-Earth object 138175 (2000 EE104). This body is associated with Interplanetary Field Enhancements (IFEs), thought to be caused by interactions between the solar wind magnetic field and solid material trailing in the orbit of the parent body. Based on optical photometry, the radius (in meters) and mass (in kilograms) of an equal-area sphere are found to be r_n = 250(0.1/p_R)**0.5 and M_n = 1e11(0.1/p_R)**1.5, respectively, where p_R is the red geometric albedo and density 1500 kg/m3 is assumed. The measured colors are intermediate between those of C-type (primitive) and S-type (metamorphosed) asteroids but, with correction for the likely effects of phase-reddening, are more consistent with a C-type classification than with S-type. No evidence for co-moving companions larger than about 40(0.1/p_R) meter in radius is found, and no dust particle trail is detected, setting a limit to the trail optical depth 2e-9. Consideration of the size distribution produced by impact pulverization makes it difficult to generate the mass of nanodust (minimum 1e5 kg to 1e6 kg) required to account for IFEs, unless the size distribution is unusually steep. Furthermore, impact pulverization timescales for source objects of the required size are much longer than the dynamical timescale. While the new optical data do not definitively refute the hypothesis that boulder pulverization is the source of IFEs, neither do they provide any support for it.
Periodic Points and Topological Restriction Homology

We answer in the affirmative two conjectures made by Klein and Williams. First, in a range of dimensions, the equivariant Reidemeister trace defines a complete obstruction to removing $n$-periodic points from a self-map $f$. Second, this obstruction defines a class in topological restriction homology. We prove these results using duality and trace for bicategories. This allows for immediate generalizations, including a corresponding theorem for the fiberwise Reidemeister trace.
Learning stabilizable nonlinear dynamics with contraction-based regularization:

We propose a novel framework for learning stabilizable nonlinear dynamical systems for continuous control tasks in robotics. The key contribution is a control-theoretic regularizer for dynamics fit...
The fading of R Coronae Borealis.

Using the International Ultraviolet Explorer (IUE) low-resolution spectra were obtained of R CrB, the prototype of its class of variable stars, shortly after the beginning of its 1983-84 minimum and during its rise to maximum again. The behavior of the spectra during the rise to maximum is similar to the behavior of the spectra of RY Sgr during a similar phase in 1979-80. The extinction data have been analyzed using Mie theory and are consistent with the stellar photosphere being obscured by 20-nm glassy carbon particles. The observations during the decline to minimum show substantial spectral variations which cannot be explained in terms of simple continuum absorption. An interpretation of the observed behavior in terms of a model incorporating an occulting cloud and circumstellar emission is offered.
Categorias desajustadas: uma crítica à teoria dual de sistemas de Nancy Fraser

Resumo O texto e uma critica a dualidade entre reconhecimento e redistribuicao e, mais pontualmente, entre acao afirmativa e acao transformadora, em textos da filosofa norte-americana Nancy Fraser. Segundo a critica aqui presente, a abordagem de Fraser nao e capaz de ultrapassar seu carater dicotomico, mesmo quando sustenta que estabelece umcontinuum entre injusticas socio-economicas e identitarias. Isso ocorre porque as injusticas, na proposta de Fraser, sao reduzidas a duas categorias, mutuamente excludentes, ou a interseccao entre elas. A posicao sustentada no texto e a de que a economia politica permeia o cultural sem deixar de ser material e que a “cultura” e economica em sua producao, distribuicao e efeitos, incluindo seus impactos para a reproducao das relacoes de classe. Palavras-chave: Nancy Fraser; dualidade; reconhecimento; distribuicao; identidades; classes. Abstract The article is a critique on the duality between recognition and redistribution and, more specifically, between affirmative action and transformative action, in texts of the American philosopher Nancy Fraser. According to such critique, Fraser’s approach is not capable of surpassing its dichotomous character, even when sustaining that it establishes a continuum between socioeconomic and identity injustices. This occurs because injustices, in Fraser’s proposal, are reduced to two mutually exclusory categories, or to the intersection between them. The position supported by the article is that the political economy permeates the cultural domain without losing its materiality, and that “culture” is economic in its production, distribution and effects, including its impacts over the reproduction of class relations. Keywords: Nancy Fraser; duality; recognition; distribution; identity; classes.
Unravelling effective professional development: a rhizomatic inquiry into coaching and the active ingredients of teacher learning

Teacher professional development (PD) is about change. One of the most prominent lines of research on PD addresses what makes it an effective change process. This research produces critical feature...
Existence and uniqueness of global Koopman eigenfunctions for stable fixed points and periodic orbits

Abstract We consider C 1 dynamical systems having an attracting hyperbolic fixed point or periodic orbit and prove existence and uniqueness results for C k (actually C loc k , α ) linearizing semiconjugacies – of which Koopman eigenfunctions are a special case – defined on the entire basin of attraction. Our main results both generalize and sharpen Sternberg’s C k linearization theorem for hyperbolic sinks, and in particular our corollaries include uniqueness statements for Sternberg linearizations and Floquet normal forms. Using our main results we also prove new existence and uniqueness statements for C k Koopman eigenfunctions, including a complete classification of C ∞ eigenfunctions assuming a C ∞ dynamical system with semisimple and nonresonant linearization. We give an intrinsic definition of ”principal Koopman eigenfunctions” which generalizes the definition of Mohr and Mezic for linear systems, and which includes the notions of ”isostables” and ”isostable coordinates” appearing in work by Ermentrout, Mauroy, Mezic, Moehlis, Wilson, and others. Our main results yield existence and uniqueness theorems for the principal eigenfunctions and isostable coordinates and also show, e.g., that the (a priori non-unique) ”pullback algebra” defined in Mohr and Mezic (2016) is unique under certain conditions. We also discuss the limit used to define the ”faster” isostable coordinates in Wilson and Ermentrout (2018), Monga et al. (2019) in light of our main results.
Quantitative Estimates on the Singular Sets of Alexandrov Spaces

Let $$X\in \text {Alex}\,^n(-1)$$ be an n-dimensional Alexandrov space with curvature $$\ge -1$$ . Let the r-scale $$(k,\epsilon )$$ -singular set $${\mathcal {S}}^k_{\epsilon ,\,r}(X)$$ be the collection of $$x\in X$$ so that $$B_r(x)$$ is not $$\epsilon r$$ -close to a ball in any splitting space $$\mathbb {R}^{k+1}\times Z$$ . We show that there exists $$C(n,\epsilon )>0$$ and $$\beta (n,\epsilon )>0$$ , independent of the volume, so that for any disjoint collection $$\big \{B_{r_i}(x_i):x_i\in {\mathcal {S}}_{\epsilon ,\,\beta r_i}^k(X)\cap B_1, \,r_i\le 1\big \}$$ , the packing estimate $$\sum r_i^k\le C$$ holds. Consequently, we obtain the Hausdorff measure estimates $${\mathcal {H}}^k({\mathcal {S}}^k_\epsilon (X)\cap B_1)\le C$$ and $${\mathcal {H}}^n\big (B_r ({\mathcal {S}}^k_{\epsilon ,\,r}(X))\cap B_1(p)\big )\le C\,r^{n-k}$$ . This answers an open question in Kapovitch et al. (Metric-measure boundary and geodesic flow on Alexandrov spaces. arXiv:1705.04767 (2017)). We also show that the k-singular set $$\textstyle{\mathcal {S}}^k(X)=\bigcup_{\epsilon>0}\big(\bigcap_{r>0}{\mathcal {S}}^k_{\epsilon ,\,r}\big)$$ is k-rectifiable and construct examples to show that such a structure is sharp. For instance, in the $$k=1$$ case we can build for any closed set $$T\subseteq \mathbb {S}^1$$ and $$\epsilon >0$$ a space $$Y\in \text {Alex}^3(0)$$ with $${\mathcal {S}}^{1}_\epsilon (Y)=\phi (T)$$ , where $$\phi :\mathbb {S}^1\rightarrow Y$$ is a bi-Lipschitz embedding. Taking T to be a Cantor set it gives rise to an example where the singular set is a 1-rectifiable, 1-Cantor set with positive 1-Hausdorff measure.
Deep Small Bowel Segmentation with Cylindrical Topological Constraints

We present a novel method for small bowel segmentation where a cylindrical topological constraint based on persistent homology is applied. To address the touching issue which could break the applied constraint, we propose to augment a network with an additional branch to predict an inner cylinder of the small bowel. Since the inner cylinder is free of the touching issue, a cylindrical shape constraint applied on this augmented branch guides the network to generate a topologically correct segmentation. For strict evaluation, we achieved an abdominal computed tomography dataset with dense segmentation ground-truths. The proposed method showed clear improvements in terms of four different metrics compared to the baseline method, and also showed the statistical significance from a paired t-test.
Effects of Radial Distances on Small-scale Magnetic Flux Ropes in the Solar Wind

Small-scale magnetic flux ropes (SFRs), in the solar wind, have been studied for decades. Statistical analysis utilizing various in situ spacecraft measurements is the main observational approach which helps investigate the generation and evolution of these small-scale structures. Based on the Grad-Shafranov (GS) reconstruction technique, we use the automated detection algorithm to build the databases of these small-scale structures via various spacecraft measurements at different heliocentric distances. We present the SFR properties including the magnetic field and plasma parameters at different radial distances from the sun near the ecliptic plane. It is found that the event occurrence rate is still in the order of a few hundreds per month, the duration and scale size distributions follow power laws, and the flux rope axis orientations are approximately centered around the local Parker spiral directions. In general, most SFR properties exhibit radial decays. In addition, with various databases established, we derive scaling laws for the changes of average field magnitude, event counts, and SFR scale sizes, with respect to the radial distances, ranging from $\sim$ 0.3 au for Helios to $\sim$ 7 au for the Voyager spacecraft. The implications of our results for comparisons with the relevant theoretical works and for the application to the Parker Solar Probe (PSP) mission are discussed.
A NEW MODEL FOR DARK MATTER HALOS HOSTING QUASARS

A new model for quasar-hosting dark matter halos, meeting two physical conditions, is put forth. First, significant interactions are taken into consideration to trigger quasar activities. Second, satellites in very massive halos at low redshift are removed from consideration due to their deficiency in cold gas. We analyze the Millennium Simulation to find halos that meet these two conditions and simultaneously match two-point auto-correlation functions of quasars and cross-correlation functions between quasars and galaxies at z = 0.5-3.2. The masses of the quasar hosts found decrease with decreasing redshift, with the mass thresholds being [(2-5) × 1012, (2-5) × 1011, (1-3) × 1011] M ☉ for median luminosities of ~[1046, 1046, 1045] erg s–1 at z = (3.2, 1.4, 0.53), respectively, an order of magnitude lower than those inferred based on halo occupation distribution modeling. In this model, quasar hosts are primarily massive central halos at z ≥ 2-3 but increasingly dominated by lower mass satellite halos experiencing major interactions toward lower redshift. However, below z = 1, satellite halos in groups more massive than ~2 × 1013 M ☉ do not host quasars. Whether for central or satellite halos, imposing the condition of significant interactions substantially boosts the clustering strength compared to the total population with the same mass cut. The inferred lifetimes of quasars at z = 0.5-3.2 of 3-30 Myr are in agreement with observations. Quasars at z ~ 2 would be hosted by halos of mass ~5 × 1011 M ☉ in this model, compared to ~3 × 1012 M ☉ previously thought, which would help reconcile with the observed, otherwise puzzling high covering fractions for Lyman limit systems around quasars.
Can the Dustiest Main Sequence Stars Tell Us About the Rocky Planet Formation Process

Main sequence stars hosting extreme quantities of inner planetary system debris are likely experiencing transient dust production events. The nature of these events, if they can be unambiguously attributed to a single process, can potentially inform us on the formation and/or early evolution of rocky Earth-like planets. In this contribution I examine some of the dustiest main sequence stars known and three processes that may be capable of reproducing their observed properties. Through this activity I also make an estimate for the likelihood of an A-type star to have an asteroid belt-like planetesimal population.
DERIVING TELESCOPE MUELLER MATRICES USING DAYTIME SKY POLARIZATION OBSERVATIONS

Telescopes often modify the input polarization of a source so that the measured circular or linear output state of the optical signal can be significantly different from the input. This mixing, or polarization "cross talk," is defined by the optical system Mueller matrix. We describe an efficient method here for recovering the input polarization state of the light and the full 4 × 4 Mueller matrix of the telescope with an accuracy of a few percent without external masks or telescope hardware modification. Observations of the bright, highly polarized daytime sky using the Haleakala 3.7 m AEOS telescope and a coude spectropolarimeter demonstrate the technique.
Multi-Agent Coverage Control with Energy Depletion and Repletion

We develop a hybrid system model to describe the behavior of multiple agents cooperatively solving an optimal coverage problem under energy depletion and repletion constraints. The model captures the controlled switching of agents between coverage (when energy is depleted) and battery charging (when energy is replenished) modes. It guarantees the feasibility of the coverage problem by defining a guard function on each agent's battery level to prevent it from dying on its way to a charging station. The charging station plays the role of a centralized scheduler to solve the contention problem of agents competing for the only charging resource in the mission space. The optimal coverage problem is transformed into a parametric optimization problem to determine an optimal recharging policy. This problem is solved through the use of Infinitesimal Perturbation Analysis (IPA), with simulation results showing that a full recharging policy is optimal.
High Energy Neutrinos from Recent Blazar Flares

The energy density of cosmic neutrinos measured by IceCube matches the one observed by Fermi in extragalactic photons that predominantly originate in blazars. This has inspired attempts to match Fermi sources with IceCube neutrinos. A spatial association combined with a coincidence in time with a flaring source may represent a smoking gun for the origin of the IceCube flux. In 2015 June, the Fermi Large Area Telescope observed an intense flare from blazar 3C 279 that exceeded the steady flux of the source by a factor of 40 for the duration of a day. We show that IceCube is likely to observe neutrinos, if indeed hadronic in origin, in data that are still blinded at this time. We also discuss other opportunities for coincident observations that include a recent flare from blazar 1ES 1959+650 that previously produced an intriguing coincidence with AMANDA observations.
The Blue Stragglers of the Old Open Cluster NGC 188

The old (7 Gyr) open cluster NGC 188 has yielded a wealth of astrophysical insight into its rich blue straggler population. Specifically, the NGC 188 blue stragglers are characterised by: A binary frequency of 80 % for orbital periods less than 104 days; Typical orbital periods around 1,000 days; Typical secondary star masses of 0.5 M⊙; At least some white dwarf companion stars; Modestly rapid rotation; A bimodal radial spatial distribution; Dynamical masses greater than standard stellar evolution masses (based on short-period binaries); Underluminosity for dynamical masses (short-period binaries).
The light radion window

Inspired by the Contino-Pomarol-Rattazzi mechanism we explore scenarios with a very light (1 keV to 10 GeV) radion which could be associated with the suppression of the electroweak contribution to vacuum energy. We construct explicit, realistic models that realize this mechanism and explore the phenomenological constraints on this class of models. Compared with axion-like particles in this mass range, the bounds from SN 1987a and from cosmology can be much weaker, depending on the mass of the radion and its coupling to other particles. With couplings suppressed by a scale lower than 100 TeV, much of the mass window from 100 keV to 10 GeV is still open.
Advanced ACTPol Low Frequency Array: Readout and Characterization of Prototype 27 and 39 GHz Transition Edge Sensors

Advanced ACTPol (AdvACT) is a third-generation polarization upgrade to the Atacama Cosmology Telescope, designed to observe the cosmic microwave background (CMB). AdvACT expands on the 90 and 150 GHz transition edge sensor (TES) bolometer arrays of the ACT Polarimeter (ACTPol), adding both high-frequency (HF, 150/230 GHz) and low-frequency (LF, 27/39 GHz) multichroic arrays. The addition of the high- and low-frequency detectors allows for the characterization of synchrotron and spinning dust emission at the low frequencies and foreground emission from galactic dust and dusty star-forming galaxies at the high frequencies. The increased spectral coverage of AdvACT will enable a wide range of CMB science, such as improving constraints on dark energy, the sum of the neutrino masses, and the existence of primordial gravitational waves. The LF array will be the final AdvACT array, replacing one of the MF arrays for a single season. Prior to the fabrication of the final LF detector array, we designed and characterized prototype TES bolometers. Detector geometries in these prototypes are varied in order to inform and optimize the bolometer designs for the LF array, which requires significantly lower noise levels and saturation powers (as low as $${\sim }\,1$$ pW) than the higher-frequency detectors. Here we present results from tests of the first LF prototype TES detectors for AdvACT, including measurements of the saturation power, critical temperature, thermal conductance, and time constants. We also describe the modifications to the time-division SQUID readout architecture compared to the MF and HF arrays.
The motive of a classifying space

The Chow group of algebraic cycles generally does not satisfy the Kunneth formula. Nonetheless, there are some schemes X over a field k which satisfy the Chow Kunneth property that the product CH∗X ⊗Z CH∗Y → CH∗(X ×k Y ) is an isomorphism for all separated schemes Y of finite type over k. The Chow Kunneth property implies the weak Chow Kunneth property that CH∗X → CH∗(XF ) is surjective for every finitely generated field F over k (or, equivalently, for every extension field F of k). We characterize several properties of this type. (We also prove versions of all our results with coefficients in a given commutative ring.) Our characterizations of Kunneth properties are: first, a smooth proper scheme X over k satisfies the weak Chow Kunneth property if and only if the Chow motive of X is a summand of a finite direct sum of Tate motives (Theorem 4.1). (This is related to known results by Bloch, Srinivas, Jannsen, Kimura, and others.) A more novel result is about an arbitrary separated scheme X of finite type over k. We say that X satisfies the motivic Kunneth property if the Kunneth spectral sequence converges to the motivic homology groups of X ×k Y for all Y . (Motivic homology groups are also called higher Chow groups; they include the usual Chow groups as a special case.) We show that a k-scheme X satisfies the motivic Kunneth property if and only if the motive of X in Voevodsky’s derived category of motives is a mixed Tate motive (Theorem 7.2). (An example of a scheme with these properties is any linear scheme, as discussed in section 5.) Finally, if a smooth but not necessarily proper k-variety X satisfies the weak Chow Kunneth property, then the birational motive of X in the sense of Rost and Kahn-Sujatha is isomorphic to the birational motive of a point (Corollary 2.2). The last result cannot be strengthened to say that the motive of X is mixed Tate; one has to consider motivic homology groups to get that conclusion. For example, the complement X of a curve of genus 1 in the affine plane has the Chow Kunneth property, since CHi+2(X ×k Y ) ∼= CHiY for all separated k-schemes Y of finite type and all i; but the motive of X is not mixed Tate. As an application of these general results, we disprove the weak Chow Kunneth property for some classifying spaces BG. For an affine group scheme G of finite type over a field k, Morel-Voevodsky and I constructed BG as a direct limit of smooth k-varieties, quotients by G of open subsets of representations of G over k [41, section 4.2], [55, 57]. As a result, the Chow ring of BG makes sense. The Chow ring of BG tensored with the rationals is easy to compute; for example, if G is finite, then CH i(BG)⊗Q = 0 for i > 0. The challenge is to understand the integral or mod p Chow ring of BG. For many finite groups G and fields k, the classifying space BG over k satisfies the Chow Kunneth property that CH∗BG ⊗Z CH∗Y ∼= CH∗(BG ×k Y ) for all separated k-schemes Y of finite type. For example, an abelian p-groupG of exponent
Fractional Korn and Hardy-type inequalities for vector fields in half space

We prove a fractional Hardy-type inequality for vector fields over the half space based on a modified fractional semi-norm. A priori, the modified semi-norm is not known to be equivalent to the sta...
Fast automatic Bayesian cubature using lattice sampling

Automatic cubatures approximate integrals to user-specified error tolerances. For high-dimensional problems, it is difficult to adaptively change the sampling pattern, but one can automatically determine the sample size, n, given a reasonable, fixed sampling pattern. We take this approach here using a Bayesian perspective. We postulate that the integrand is an instance of a Gaussian stochastic process parameterized by a constant mean and a covariance kernel defined by a scale parameter times a parameterized function specifying how the integrand values at two different points in the domain are related. These hyperparameters are inferred or integrated out using integrand values via one of three techniques: empirical Bayes, full Bayes, or generalized cross-validation. The sample size, n, is increased until the half-width of the credible interval for the Bayesian posterior mean is no greater than the error tolerance. The process outlined above typically requires a computational cost of $$O(N_{\text {opt}}n^3)$$, where $$N_{\text {opt}}$$ is the number of optimization steps required to identify the hyperparameters. Our innovation is to pair low discrepancy nodes with matching covariance kernels to lower the computational cost to $$O(N_{\text {opt}} n \log n)$$. This approach is demonstrated explicitly with rank-1 lattice sequences and shift-invariant kernels. Our algorithm is implemented in the Guaranteed Automatic Integration Library (GAIL).
Machine and deep learning applications in particle physics

The many ways in which machine and deep learning are transforming the analysis and simulation of data in particle physics are reviewed. The main methods based on boosted decision trees and various ...
Cup-length estimates for leaf-wise intersections

We prove that on a restricted contact type hypersurface the number of leaf-wise intersections is bounded from below by a certain cup-length.
Perturbative versus lattice QCD energy density correlators at high temperatures

Abstract Correlators of magnetic and electric field energy density are investigated for SU( N c ) gauge theory at high temperatures T . A separations z ⩽ 2/ T the correlators are shown to be dominated by a power-law behavior even for finite gluon screening masses. This continuum behavior is well approximated on current 4 × 16 3 -lattices in the perturbative limit and leads to a considerable overestimate of screening masses deduced from fitting the lattice correlators with conventional exponential forms. The use of extended sources and sinks to enhance the signal improves the situation for screening masses m ⪢ T but leads to a largely uncontrolled error for masses less than T . In fact, we show that recent lattice QCD data of Grossmann et al., from which a magnetic screening mass m M ∼ 2.9 T was deduced, may even be consistent with a vanishing actual magnetic screening mass.
Weighted persistent homology

We introduce weighted versions of the classical Cech and Vietoris–Rips complexes. We show that a version of the Vietoris–Rips lemma holds for these weighted complexes and that they enjoy appropriate stability properties. We also give some preliminary applications of these weighted complexes.
Double Neutron Star Mergers from Hierarchical Triple-star Systems

The isolated binary evolution model for merging neutron stars (NSs) involves processes such as mass transfer, common-envelope evolution, and natal kicks, all of which are poorly understood. Also, the predicted NS-NS merger rates are typically lower than the rates inferred from the LIGO GW170817 event. Here, we investigate merger rates of NS and black hole (BH)-NS binaries in hierarchical triple-star systems. In such systems, the tertiary can induce Lidov-Kozai (LK) oscillations in the inner binary, accelerating its coalescence, and potentially enhancing compact object merger rates. However, since compact objects originate from massive stars, the prior evolution should also be taken into account. Natal kicks, in particular, could significantly reduce the rates by unbinding the tertiary before it can affect the inner binary through LK evolution. We carry out simulations of massive triples taking into account stellar evolution starting from the main sequence, secular and tidal evolution, and the effects of supernovae. For large NS birth kicks (\sigma_k = 265 km/s), we find that the triple NS-NS merger rate (several hundred Gpc^{-3} yr^{-1}) is lower by a factor of ~2-3 than the binary rate, but for no kicks (\sigma_k = 0 km/s), the triple rate (several thousand Gpc^{-3} yr^{-1}) is comparable to the binary rate. Our results indicate that a significant fraction of NS-NS mergers could originate from triples if a substantial portion of the NS population is born with low kick velocities, as indicated by other work. However, uncertainties and open questions remain because of our simplifying assumption of dynamical decoupling after inner binary interaction has been triggered.
A SEMI-LAGRANGIAN TWO-LEVEL PRECONDITIONED NEWTON-KRYLOV SOLVER FOR CONSTRAINED DIFFEOMORPHIC IMAGE REGISTRATION.

We propose an efficient numerical algorithm for the solution of diffeomorphic image registration problems. We use a variational formulation constrained by a partial differential equation (PDE), where the constraints are a scalar transport equation. We use a pseudospectral discretization in space and second-order accurate semi-Lagrangian time stepping scheme for the transport equations. We solve for a stationary velocity field using a preconditioned, globalized, matrix-free Newton--Krylov scheme. We propose and test a two-level Hessian preconditioner. We consider two strategies for inverting the preconditioner on the coarse grid: A nested preconditioned conjugate gradient method (exact solve) and a nested Chebyshev iterative method (inexact solve) with a fixed number of iterations. We test the performance of our solver in different synthetic and real-world two-dimensional application scenarios. We study grid convergence and computational efficiency of our new scheme. We compare the performance of our solve...
Loop Quantum Cosmology: An Overview

A brief overview of loop quantum cosmology of homogeneous isotropic models is presented with emphasis on the origin of and subtleties associated with the resolution of big bang and big crunch singularities. These results bear out the remarkable intuition that John Wheeler had. Discussion is organized at two levels. The the main text provides a bird’s eye view of the subject that should be accessible to non-experts. Appendices address conceptual and technical issues that are often raised by experts in loop quantum gravity and string theory.
The Evryscope: the first full-sky gigapixel-scale telescope

Current time-domain wide-field sky surveys generally operate with few-degree-sized fields and take many individual images to cover large sky areas each night. We present the design and project status of the Evryscope (“wideseer”), which takes a different approach: using an array of 7cm telescopes to form a single wide-field-of-view pointed at every part of the accessible sky simultaneously and continuously. The Evryscope is a gigapixel-scale imager with a 9060 sq. deg. field of view and has an etendue three times larger than the Pan-STARRS sky survey. The system will search for transiting exoplanets around bright stars, M-dwarfs and white dwarfs, as well as detecting microlensing events, nearby supernovae, and gamma-ray burst afterglows. We present the current project status, including an update on the Evryscope prototype telescopes we have been operating for the last three years in the Canadian High Arctic.
A PHENOMENOLOGICAL THEORY OF FERMION MASSES AND MIXINGS

A phenomenological theory of fermion masses and mixings is constructed within the framework of a four-family symmetry. It is found that the most favored set of relevant CKM elements are |Vus| ≈ 0.222, |Vcb| ≈ 0.044, |Vub/Vcb| ≈ 0.082, |Vud| ≈ 0.974, |Vcs| ≈0.9736, |Vcd| ≈ 0.224 with $\hat B_K \approx 0.8$. The top quark mass is predicted to be 258 GeV at 1 GeV with its physical mass approximately in the range of 153 GeV to 165 GeV. Some remarks on the relationship between the lepton sector and the quark sector will be made.