cssi/SciSciGPT-SciSciNet huggingface dataset:
A Reduction from Reinforcement Learning to No-Regret Online Learning

We present a reduction from reinforcement learning (RL) to no-regret online learning based on the saddle-point formulation of RL, by which “any” online algorithm with sublinear regret can generate policies with provable performance guarantees. This new perspective decouples the RL problem into two parts: regret minimization and function approximation. The first part admits a standard online-learning analysis, and the second part can be quantified independently of the learning algorithm. Therefore, the proposed reduction can be used as a tool to systematically design new RL algorithms. We demonstrate this idea by devising a simple RL algorithm based on mirror descent and the generative-model oracle. For any γ-discounted tabular RL problem, with probability at least 1−δ, it learns an ϵ-optimal policy using at most O(|S||A|log(1/δ) / (1−γ)^4ϵ^2) samples. Furthermore, this algorithm admits a direct extension to linearly parameterized function approximators for large-scale applications, with computation and sample complexities independent of |S|,|A|, though at the cost of potential approximation bias.
Molecular Correlates of Topiramate and GRIK1 rs2832407 Genotype in Pluripotent Stem Cell–Derived Neural Cultures

Background There is growing evidence that the anticonvulsant topiramate is efficacious in reducing alcohol consumption. Further, an intronic single nucleotide polymorphism (rs2832407, C A) in the GRIK1 gene, which encodes the GluK1 subunit of the excitatory kainate receptor, predicted topiramate's effectiveness in reducing heavy drinking in a clinical trial. The molecular correlates of GRIK1 genotype that may relate to topiramate's ability to reduce drinking remain unknown. Methods We differentiated induced pluripotent stem cells (iPSCs) characterized by GRIK1 rs2832407 genotype from 8 A/A and 8 C/C donors into forebrain-lineage neural cultures. Our differentiation protocol yielded mixed neural cultures enriched for glutamatergic neurons. Basal mRNA expression of the GRIK1 locus was examined via quantitative polymerase chain reaction (qPCR). The effects of acute topiramate exposure on excitatory spontaneous synaptic activity were examined via whole-cell patch-clamp electrophysiology. Results were compared and contrasted between iPSC donor genotypes. Results Although characterization of the GRIK1 locus revealed no effect of rs2832407 genotype on GRIK1 isoform mRNA expression, a significant difference was observed on GRIK1 antisense-2 expression, which was greater in C/C neural cultures. Differential effects of acute exposure to 5 μM topiramate were observed on spontaneous synaptic activity in A/A versus C/C neurons, with a smaller reduction in excitatory event frequency observed in C/C donor neurons. Conclusions This work highlights the use of iPSC technologies to study pharmacogenetic treatment effects in psychiatric disorders and furthers our understanding of the molecular effects of topiramate exposure in human neural cells.
Fairness-Efficiency Tradeoffs in Dynamic Fair Division

A set of T indivisible goods has to be allocated to a set of n agents with additive utilities, in a way that is fair and efficient. A standard fairness concept is envy-freeness, which requires that each agent prefers her own allocation over the allocation of any other agent. Even though envy is clearly unavoidable in this context - consider the case of a single indivisible good and two agents - providing approximately envy-free solutions is possible [3, 6]. Specifically, an allocation is envy-free up to one item (EF1) if for every pair of agents i and j, any envy i has for j can be eliminated by removing at most one good from j's bundle. Recently, Caragiannis et al. [3] show that the allocation that maximizes the product of the agents' utilities (with ties broken based on the number of agents with positive utility) is EF1 and Pareto efficient. The majority of the literature to date has focused on the case where the items are available to the algorithm upfront. In many situations of interest, however, items arrive online. A paradigmatic example is that of food banks [1, 5]. Food banks across the world receive food donations they must allocate; these donations are often perishable, and thus allocation decisions must be made quickly, and donations are typically leftovers, leading to uncertainty about items that will arrive in the future. Benade et al. [2] study this problem, but focus only on fairness. They show that there exists a deterministic algorithm with vanishing envy, that is, the maximum pairwise envy (after all T items have been allocated) is sublinear in T , when the value vit of agent i for the t-th item is normalized to be in [0, 1]. Specifically, the envy is guaranteed to be at most O(√p T logT /n), and this guarantee is tight up to polylogarithmic factors. The same guarantee can also be achieved by the simple randomized algorithm that allocates each item to a uniformly random agent. These results hold even against an adaptive adversary that selects the value vit after seeing the allocation of the first t - 1 items. On the other hand, if we focus only on efficiency, our task is much easier. For example, we could simply allocate each item to the agent with the highest value. But, and this brings us to our interest here, the question remains: How should we make allocation decisions online in a way that is fair to the donation recipients, but also as efficient as possible?
The lowest-order stabilizer free weak Galerkin finite element method

Abstract Recently, a new stabilizer free weak Galerkin method (SFWG) is proposed, which is easier to implement and more efficient. The main idea is that by letting j ≥ j 0 for some j 0 , where j is the degree of the polynomials used to compute the weak gradients, then the stabilizer term in the regular weak Galerkin method is no longer needed. Later on in [1] , the optimal of such j 0 for a certain type of finite element spaces was given. In this paper, we propose a new efficient SFWG scheme using the lowest possible orders of piecewise polynomials for triangular meshes in 2D with the optimal order of convergence.
Impact of percent positive biopsy cores on cancer-specific mortality for patients with high-risk prostate cancer.

ABSTRACT Objective A high percent positive biopsy cores (PBC), typically dichotomized at ≥50% is prognostic of worse cancer-specific outcomes for patients with low- and intermediate-risk prostate cancer (CaP). The clinical significance of ≥50% PBC for patients with high-risk disease is poorly understood. We examined the association between ≥50% PBC, compared to Materials and methods We identified 7,569 men from the Surveillance, Epidemiology, and End Results program who were diagnosed with high-risk CaP (Gleason score of 8–10, prostate-specific antigen >20 ng/mL, or cT3-T4 stage) in 2010–2011 and had 6 to 24 cores sampled at biopsy. Multivariable Fine and Gray competing risks regression was utilized to examine the association between ≥50% PBC and PCSM. Results Median follow-up was 3.8 years. 56.2% of patients (4,253) had ≥50% PBC. On competing risks regression, ≥50% PBC was associated with a significantly higher risk of PCSM compared to Conclusion In this large cohort of patients with high-risk CaP, ≥50% PBC was independently associated with an approximately 2-fold increased risk of PCSM for patients with cT1–T2, but not cT3–T4, tumors. Percent PBC, which is a widely available clinical value, should be routinely used to risk stratify men with high-risk disease and identify patients whom may benefit from treatment intensification.
Robust Approximate Simulation for Hierarchical Control of Linear Systems under Disturbances.

Approximate simulation, an extension of simulation relations from formal methods to continuous systems, is a powerful tool for hierarchical control of complex systems. Finding an approximate simulation relation between the full "concrete" system and a simplified "abstract" system establishes a bound on the output error between the two systems, allowing one to design a controller for the abstract system while formally certifying performance on the concrete system. However, many real-world control systems are subject to external disturbances, which are not accounted for in the standard approximate simulation framework. We present a notion of robust approximate simulation, which considers external disturbances to the concrete system. We derive output error bounds for the case of linear systems subject to two types of additive disturbances: bounded disturbances and a sequence of (unbounded) impulse disturbances. We demonstrate the need for robust approximate simulation and the effectiveness of our proposed approach with a simulated robot motion planning example.
Distributed Non-convex Optimization of Multi-agent Systems Using Boosting Functions to Escape Local Optima.

We address the problem of multiple local optima arising due to non-convex objective functions in cooperative multi-agent optimization problems. To escape such local optima, we propose a systematic approach based on the concept of boosting functions. The underlying idea is to temporarily transform the gradient at a local optimum into a boosted gradient with a non-zero magnitude. We develop a Distributed Boosting Scheme (DBS) based on a gradient-based optimization algorithm using a novel optimal variable step size mechanism so as to guarantee convergence. Even though our motivation is based on the coverage control problem setting, our analysis applies to a broad class of multi-agent problems. Simulation results are provided to compare the performance of different boosting functions families and to demonstrate the effectiveness of the boosting function approach in attaining improved (still generally local) optima.
Hitting sets give two-sided derandomization of small space

A hitting set is a "one-sided" variant of a pseudorandom generator (PRG), naturally suited to derandomizing algorithms that have one-sided error. We study the problem of using a given hitting set to derandomize algorithms that have two-sided error, focusing on space-bounded algorithms. For our first result, we show that if there is a log-space hitting set for polynomial-width read-once branching programs (ROBPs), then not only does L = RL, but L = BPL as well. This answers a question raised by Hoza and Zuckerman [16].Next, we consider constant-width ROBPs. We show that if there are log-space hitting sets for constant-width ROBPs, then given black-box access to a constant-width ROBP f, it is possible to deterministically estimate E[f] to within ±e in space O(log(n/e)). Unconditionally, we give a deterministic algorithm for this problem with space complexity O(log2n + log(1/e)), slightly improving over previous work.Finally, we investigate the limits of this line of work. Perhaps the strongest reduction along these lines one could hope for would say that for every explicit hitting set, there is an explicit PRG with similar parameters. In the setting of constant-width ROBPs over a large alphabet, we prove that establishing such a strong reduction is at least as difficult as constructing a good PRG outright. Quantitatively, we prove that if the strong reduction holds, then for every constant α > 0, there is an explicit PRG for constant-width ROBPs with seed length O(log1+αn). Along the way, unconditionally, we construct an improved hitting set for ROBPs over a large alphabet.
Gravitational dipole moment from an exact solution with torsion

Dipole fields are common in electromagnetism and may be viewed as the result of a positive and negative charge (or pole) which are close together. A dipole field in gravity is not expected to exist because negative mass has never been observed. However, an exact solution to the gravitational field equations with torsion is presented that does correspond to a dipole gravitational field, even though there is no negative mass. The theory is based on a non-symmetric metric tensor, and it is found there is a singularity in the metric tensor at the origin but no event horizon. Gravitational dipoles have been used to solve the dark matter problem.
Analysis of stress responses in Astyanax larvae reveals heterogeneity among different populations

Stress responses are conserved physiological and behavioral outcomes as a result of facing potentially harmful stimuli, yet in pathological states, stress becomes debilitating. Stress responses vary considerably throughout the animal kingdom, but how these responses are shaped evolutionarily is unknown. The Mexican cavefish has emerged as a powerful system for examining genetic principles underlying behavioral evolution. Here, we demonstrate that cave Astyanax have reduced behavioral and physiological measures of stress when examined at larval stages. We also find increased expression of the glucocorticoid receptor, a repressible element of the neuroendocrine stress pathway. Additionally, we examine stress in three different cave populations, and find that some, but not all, show reduced stress measures. Together, these results reveal a mechanistic system by which cave-dwelling fish reduced stress, presumably to compensate for a predator poor environment.
Home Production and Leisure during the COVID-19 Recession

Between the months of February and April of 2020, average weekly market hours in the U.S. dropped by 6.25, meanwhile 36% of workers reported switching to remote work arrangements. In this paper, we examine implications of these changes for the time allocation of different households, and on aggregate. We estimate that home production activity increased by 2.65 h a week, or 42.4% of lost market hours, due to the drop in market work and rise in remote work. The monthly value of home production increased by $39.65 billion - that is 13.55% of the concurrent $292.61 billion drop in monthly GDP. Although market hours declined the most for single, less educated individuals, the lost market hours were absorbed into home production the most by married individuals with children. Adding on the impact of school closures, our estimate of weekly home production hours increases by as much as 4.92 h. The increase in the value of monthly home production between February and April updates to $73.57 billion. We also report the estimated impact of labor markets and telecommuting on home production for each month in 2020. © 2021 Walter de Gruyter GmbH, Berlin/Boston 2021.
Surrogate-guided sampling designs for classification of rare outcomes from electronic medical records data

Scalable and accurate identification of specific clinical outcomes has been enabled by machine-learning applied to electronic medical record (EMR) systems. The development of classification models requires the collection of a complete labeled data set, where true clinical outcomes are obtained by human expert manual review. For example, the development of natural language processing algorithms requires the abstraction of clinical text data to obtain outcome information necessary for training models. However, if the outcome is rare then simple random sampling results in very few cases and insufficient information to develop accurate classifiers. Since large scale detailed abstraction is often expensive, time-consuming, and not feasible, more efficient strategies are needed. Under such resource constrained settings, we propose a class of enrichment sampling designs, where selection for abstraction is stratified by auxiliary variables related to the true outcome of interest. Stratified sampling on highly specific variables results in targeted samples that are more enriched with cases, which we show translates to increased model discrimination and better statistical learning performance. We provide mathematical details, and simulation evidence that links sampling designs to their resulting prediction model performance. We discuss the impact of our proposed sampling on both model training and validation. Finally, we illustrate the proposed designs for outcome label collection and subsequent machine-learning, using radiology report text data from the Lumbar Imaging with Reporting of Epidemiology (LIRE) study.
Information Constrained Optimal Transport: From Talagrand, to Marton, to Cover

The optimal transport problem studies how to transport one measure to another in the most cost-effective way and has wide range of applications from economics to machine learning. In this paper, we introduce and study an information constrained variation of this problem. Our study yields a strengthening and generalization of Talagrand’s celebrated transportation cost inequality. Following Marton’s approach, we show that the new transportation cost inequality can be used to recover old and new concentration of measure results. Finally, we provide an application of this inequality to network information theory. We show that it can be used to recover a recent solution to a long-standing open problem posed by Cover regarding the capacity of the relay channel.
Dynamics of microbial competition, commensalism and cooperation and its implications for coculture and microbiome engineering

Microbial consortium is a complex adaptive system with higher-order dynamic characteristics that are not present by individual members. To accurately predict the social interactions, we formulate a set of unstructured kinetic models to quantitatively capture the dynamic interactions of multiple microbial species. By introducing an interaction coefficient, we analytically derived the steady-state solutions for the interacting species and the substrate-depleting profile in the chemostat. We analyzed the stability of the possible coexisting states defined by competition, parasitism, amensalism, commensalism, and cooperation. Our model predicts that only parasitism, commensalism, and cooperation could lead to stable coexisting states. We also determined the optimal social interaction criteria of microbial coculture when sequential metabolic reactions are compartmentalized into two distinct species. Coupled with Luedeking-Piret and Michaelis-Menten equations, accumulation of metabolic intermediates in one species and formation of end-product in another species could be derived and assessed. We discovered that parasitism consortia disfavor the bioconversion of intermediate to final product; and commensalism consortia could efficiently convert metabolic intermediates to final product and maintain metabolic homeostasis with a broad range of operational conditions (i.e., dilution rates); whereas cooperative consortia leads to highly nonlinear pattern of precursor accumulation and end-product formation. The underlying dynamics and emergent properties of microbial consortia may provide critical knowledge for us to understand ecological coexisting states, engineer efficient bioconversion process, deliver effective gut therapeutics as well as elucidate probiotic-pathogen or tumor-host interactions in general.
Turn-Key, High-Efficiency Kerr Comb Source

We demonstrate automated Kerr comb generation in the normal group-velocity dispersion regime. Using a coupled-ring geometry, we precisely control the spectral positions of avoided mode crossings to generate coherent combs with 41% pump-to-comb conversion efficiencies.
Visual Input into the Drosophila melanogaster Mushroom Body

Summary The patterns of neuronal connectivity underlying multisensory integration, a fundamental property of many brains, remain poorly characterized. The Drosophila melanogaster mushroom body—an associative center—is an ideal system to investigate how different sensory channels converge in higher order brain centers. The neurons connecting the mushroom body to the olfactory system have been described in great detail, but input from other sensory systems remains poorly defined. Here, we use a range of anatomical and genetic techniques to identify two types of input neuron that connect visual processing centers—the lobula and the posterior lateral protocerebrum—to the dorsal accessory calyx of the mushroom body. Together with previous work that described a pathway conveying visual information from the medulla to the ventral accessory calyx of the mushroom body, our study defines a second, parallel pathway that is anatomically poised to convey information from the visual system to the dorsal accessory calyx.
Astrocytes are necessary for blood-brain barrier maintenance in the adult mouse brain.

In the adult brain, multiple cell types are known to produce factors that regulate blood-brain barrier (BBB) properties, including astrocytes. Yet several recent studies disputed a role for mature astrocytes at the BBB. To determine if astrocytes contribute a nonredundant and necessary function in maintaining the adult BBB, we used a mouse model of tamoxifen-inducible astrocyte ablation. In adult mice, tamoxifen induction caused sparse apoptotic astrocyte cell death within 2 hr. Indicative of BBB damage, leakage of the small molecule Cadaverine, and the large plasma protein fibrinogen into the brain parenchyma indicative of BBB damage was detected as early as astrocyte ablation was present. Vessels within and close to regions of astrocyte loss had lower expression of the tight junction protein zonula occludens-1 while endothelial glucose transporter 1 expression was undisturbed. Cadaverine leakage persisted for several weeks suggesting a lack of barrier repair. This is consistent with the finding that ablated astrocytes were not replaced. Adjacent astrocytes responded with partial nonproliferative astrogliosis, characterized by morphological changes and delayed phosphorylation of STAT3, which restricted dye leakage to the brain and vessel surface areas lacking coverage by astrocytes 1 month after ablation. In conclusion, astrocytes are necessary to maintain BBB integrity in the adult brain. BBB-regulating factors secreted by other cell types, such as pericytes, are not sufficient to compensate for astrocyte loss.
Deep profiling of protease substrate specificity enabled by dual random and scanned human proteome substrate phage libraries

Proteolysis is a major posttranslational regulator of biology inside and outside of cells. Broad identification of optimal cleavage sites and natural substrates of proteases is critical for drug discovery and to understand protease biology. Here, we present a method that employs two genetically encoded substrate phage display libraries coupled with next generation sequencing (SPD-NGS) that allows up to 10,000-fold deeper sequence coverage of the typical six- to eight-residue protease cleavage sites compared to state-of-the-art synthetic peptide libraries or proteomics. We applied SPD-NGS to two classes of proteases, the intracellular caspases, and the ectodomains of the sheddases, ADAMs 10 and 17. The first library (Lib 10AA) allowed us to identify 104 to 105 unique cleavage sites over a 1,000-fold dynamic range of NGS counts and produced consensus and optimal cleavage motifs based position-specific scoring matrices. A second SPD-NGS library (Lib hP), which displayed virtually the entire human proteome tiled in contiguous 49 amino acid sequences with 25 amino acid overlaps, enabled us to identify candidate human proteome sequences. We identified up to 104 natural linear cut sites, depending on the protease, and captured most of the examples previously identified by proteomics and predicted 10- to 100-fold more. Structural bioinformatics was used to facilitate the identification of candidate natural protein substrates. SPD-NGS is rapid, reproducible, simple to perform and analyze, inexpensive, and renewable, with unprecedented depth of coverage for substrate sequences, and is an important tool for protease biologists interested in protease specificity for specific assays and inhibitors and to facilitate identification of natural protein substrates.
Bio-inspired Gait Imitation of Hexapod Robot Using Event-Based Vision Sensor and Spiking Neural Network

Learning how to walk is a sophisticated neurological task for most animals. In order to walk, the brain must synthesize multiple cortices, neural circuits, and diverse sensory inputs. Some animals, like humans, imitate surrounding individuals to speed up their learning. When humans watch their peers, visual data is processed through a visual cortex in the brain. This complex problem of imitation-based learning forms associations between visual data and muscle actuation through Central Pattern Generation (CPG). Reproducing this imitation phenomenon on low power, energy-constrained robots that are learning to walk remains challenging and unexplored. We propose a bio-inspired feed-forward approach based on neuromorphic computing and event-based vision to address the gait imitation problem. The proposed method trains a "student" hexapod to walk by watching an "expert" hexapod moving its legs. The student processes the flow of Dynamic Vision Sensor (DVS) data with a one-layer Spiking Neural Network (SNN). The SNN of the student successfully imitates the expert within a small convergence time of ten iterations and exhibits energy efficiency at the sub-microjoule level.
Impacts of Expressive Writing on Children’s Anxiety and Mathematics Learning: Developmental and Gender Variability

Abstract Expressive writing (EW), or writing about one’s thoughts and feelings, has been posited to reduce the working memory (WM) load that pressure and anxiety can impose on test-takers. The mechanisms of EW are far from clear, however, and social and developmental questions about its role in shaping children’s engagement with academic contexts remain. We report a study with 250 10–12-year-olds (Mage = 11.55; SDage = 0.48; 127 females), exploring gender differences in these younger children’s use of EW before a high demand mathematics lesson on ratio. In contrast to the literature with adults, children assigned to EW had greater anxiety relative to control. The highest-achieving higher-WM girls also were most impacted by EW, showing decreases in immediate learning and retention relative to their counterparts who did not write expressively. A mediation analysis indicated that EW reduced learning gains by increasing children’s anxiety during the lesson, thereby suggesting that EW functioned quite differently from its use in older youth and adults. These data suggest that emotion regulation skills may be an under-considered mechanism that underpins benefits of EW in older adolescents and adults.
Legendre functions, spherical rotations, and multiple elliptic integrals

A closed-form formula is derived for the generalized Clebsch–Gordan integral $\int_{-1}^{1} {[}P_{\nu}(x){]}^{2}P_{\nu}(-x)\,\mathrm {d}x$ , with P ν being the Legendre function of arbitrary complex degree $\nu\in\mathbb{C}$ . The finite Hilbert transform of P ν (x)P ν (−x), −1<x<1 is evaluated. An analytic proof is provided for a recently conjectured identity $\int_{0}^{1}[\mathbf{K}( \sqrt{1-k^{2}} )]^{3}\,\mathrm {d}k=6\int_{0}^{1}[\mathbf{K}(k)]^{2}\mathbf{K}( \sqrt{1-k^{2}} )k\,\mathrm {d}k=[\Gamma (\frac{1}{4})]^{8}/(128\pi^{2}) $ involving complete elliptic integrals of the first kind K(k) and Euler’s gamma function Γ(z).
Idempotents in representation rings of quivers

For an acyclic quiver Q, we solve the Clebsch-Gordan problem for the projective representations by computing the multiplicity of a given indecomposable projective in the tensor product of two indecomposable projectives. Motivated by this problem for arbitrary representations, we study idempotents in the representation ring of Q (the free abelian group on the indecomposable representations, with multiplication given by tensor product). We give a general technique for constructing such idempotents and for decomposing the representation ring into a direct product of ideals, utilizing morphisms between quivers and categorical Moebius inversion.
Isometric embeddings into the Minkowski space and new quasi-local mass

The definition of quasi-local mass for a bounded space-like region Ω in space-time is essential in several major unsettled problems in general relativity. The quasi-local mass is expected to be a type of flux integral on the boundary two-surface $${\Sigma=\partial \Omega}$$ and should be independent of whichever space-like region $${\Sigma}$$ bounds. An important idea which is related to the Hamiltonian formulation of general relativity is to consider a reference surface in a flat ambient space with the same first fundamental form and derive the quasi-local mass from the difference of the extrinsic geometries. This approach has been taken by Brown-York [4,5] and Liu-Yau [16,17] (see also related works [3,6,9,12,14,15,28,32]) to define such notions using the isometric embedding theorem into the Euclidean three space. However, there exist surfaces in the Minkowski space whose quasilocal mass is strictly positive [19]. It appears that the momentum information needs to be accounted for to reconcile the difference. In order to fully capture this information, we use isometric embeddings into the Minkowski space as references. In this article, we first prove an existence and uniqueness theorem for such isometric embeddings. We then solve the boundary value problem for Jang’s [13] equation as a procedure to recognize such a surface in the Minkowski space. In doing so, we discover a new expression of quasi-local mass for a large class of “admissible” surfaces (see Theorem A and Remark 1.1). The new mass is positive when the ambient space-time satisfies the dominant energy condition and vanishes on surfaces in the Minkowski space. It also has the nice asymptotic behavior at spatial infinity and null infinity. Some of these results were announced in [29].
Buoyancy instabilities in degenerate, collisional, magnetized plasmas

In low-collisionality plasmas, anisotropic heat conduction due to a magnetic field leads to buoyancy instabilities for any non-zero temperature gradient. We study analogous instabilities in degenerate collisional plasmas, i.e. when the electron collision frequency is large compared to the electron cyclotron frequency. Although heat conduction is nearly isotropic in this limit, the small residual anisotropy ensures that collisional degenerate plasmas are also convectively unstable independent of the sign of the temperature gradient. We show that the range of wavelengths that are unstable is independent of the magnetic field strength, while the growth time increases with decreasing magnetic field strength. We discuss the application of these collisional buoyancy instabilities to white dwarfs and neutron stars. Magnetic tension and the low specific heat of a degenerate plasma significantly limit their effectiveness; the most promising venues for growth are in the liquid oceans of young, weakly magnetized neutron stars (B ≲ 10 9 G) and in the cores of young, high magnetic field white dwarfs (B ~ 10 9 G).
YOUNG, STAR-FORMING GALAXIES AND THEIR LOCAL COUNTERPARTS: THE EVOLVING RELATIONSHIP OF MASS–SFR–METALLICITY SINCE z ∼ 2.1

We explore the evolution of the Stellar Mass-Star Formation Rate-Metallicity Relation using a set of 256 COSMOS and GOODS galaxies in the redshift range 1.90 3 . 10^40 ergs s^-1) local galaxies, and this offset cannot be explained by simple systematic offsets in the derived quantities. At stellar masses above ~10^9 Msol and star formation rates above ~10 Msol yr^-1, the z ~ 2.1 galaxies have higher oxygen abundances than their local counterparts, while the opposite is true for lower-mass, lower-SFR systems.
Discrete Quantum Theories

We explore finite-field frameworks for quantum theory and quantum computation. The simplest theory, defined over unrestricted finite fields, is unnaturally strong. A second framework employs only finite fields with no solution to x2 + 1 = 0, and thus permits an elegant complex representation of the extended field by adjoining . Quantum theories over these fields recover much of the structure of conventional quantum theory except for the condition that vanishing inner products arise only from null states; unnaturally strong computational power may still occur. Finally, we are led to consider one more framework, with further restrictions on the finite fields, that recovers a local transitive order and a locally-consistent notion of inner product with a new notion of cardinal probability. In this framework, conventional quantum mechanics and quantum computation emerge locally (though not globally) as the size of the underlying field increases. Interestingly, the framework allows one to choose separate finite fields for system description and for measurement: the size of the first field quantifies the resources needed to describe the system and the size of the second quantifies the resources used by the observer. This resource-based perspective potentially provides insights into quantitative measures for actual computational power, the complexity of quantum system definition and evolution, and the independent question of the cost of the measurement process.
Critical surfaces for general inhomogeneous bond percolation problems

We present a method of general applicability for finding exact values or accurate approximations of bond percolation thresholds for a wide class of lattices. To every lattice we systematically associate a polynomial, the root of which in [0, 1] is the conjectured critical point. The method makes the correct prediction for every exactly solved problem, and comparison with numerical results shows that it is very close, but not exact, for many others. We focus primarily on the Archimedean lattices, in which all vertices are equivalent, but this restriction is not crucial. Some results we find are kagome: pc = 0.524 430..., (3, 122): pc = 0.740 423..., (33, 42): pc = 0.419 615..., (3, 4, 6, 4): pc = 0.524 821..., (4, 82): pc = 0.676 835..., (32, 4, 3, 4): pc = 0.414 120... . The results are generally within 10 − 5 of numerical estimates. For the inhomogeneous checkerboard and bow-tie lattices, errors in the formulae (if they are not exact) are less than 10 − 6.
Matrix theories from reduced SU(N) Yang-Mills with adjoint fermions

Abstract We consider a dimensional reduction of 3+1 dimensional SU ( N ) Yang-Mills theory coupled to adjoint fermions to obtain a class of 1 + 1 dimensional matrix field theories. We derive the quantized light-cone Hamiltonian in the light-cone gauge A _ = 0 and large- N limit, and then solve for the masses, wavefunctions and structure functions of the color singlet boson and fermion bound states. Among the states we study are many massless string-like states that can be solved for exactly.
COUPLING CONVECTIVELY DRIVEN ATMOSPHERIC CIRCULATION TO SURFACE ROTATION: EVIDENCE FOR ACTIVE METHANE WEATHER IN THE OBSERVED SPIN RATE DRIFT OF TITAN

A large drift in the rotation rate of Titan observed by Cassini provided the first evidence of a subsurface ocean isolating the massive core from the icy crust. Seasonal exchange of angular momentum between the surface and atmosphere accounts for the magnitude of the effect, but observations lag the expected signal by a few years. We argue that this time lag is due to the presence of an active methane weather cycle in the atmosphere. An analytic model of the seasonal cycle of atmospheric angular momentum is developed and compared with time-dependent simulations of Titan's atmosphere with and without methane thermodynamics. The disappearance of clouds at the summer pole suggests the drift rate has already switched direction, signaling the change in season from solstice to equinox.
NEUTRON SCATTERING SIGNATURE OF d-DENSITY WAVE ORDER IN THE CUPRATES

An ordered d-density wave (DDW) state has been proposed as an explanation of the pseudogap phase in underdoped high-temperature superconductors. The staggered currents associated with this order have signatures which are qualitatively different from those of ordered spins. We apply the order parameter theory to an orthorhombic bilayer system and show that the expected magnitude as well as the momentum, energy, and polarization dependence of the consequent neutron scattering is consistent with the findings of a recent experiment.
3D woodpile structure tunable plasma photonic crystal

A 3D woodpile structure tunable plasma photonic crystal is designed, simulated, and experimentally characterized over the S - X band of the electromagnetic spectrum. The measurements confirm that the electromagnetic response is rich in dynamics. The photonic crystal's reconfigurability, achieved through individual discharge control of the properties of the woodpile plasma columns, offers an unprecedented opportunity to better resolve the interactions between both the Bragg and localized surface plasmon modes which dominate the spectrum at lower frequencies. Both the experiments and simulations reveal evidence for the coupling of Bragg and surface plasmon modes through a Fano resonance.
QuSpin: a Python package for dynamics and exact diagonalisation of quantum many body systems part I: spin chains

We present a new open-source Python package for exact diagonalization and quantum dynamics of spin(-photon) chains, called QuSpin, supporting the use of various symmetries in 1-dimension and (imaginary) time evolution for chains up to 32 sites in length. The package is well-suited to study, among others, quantum quenches at finite and infinite times, the Eigenstate Thermalisation hypothesis, many-body localisation and other dynamical phase transitions, periodically-driven (Floquet) systems, adiabatic and counter-diabatic ramps, and spin-photon interactions. Moreover, QuSpin's user-friendly interface can easily be used in combination with other Python packages which makes it amenable to a high-level customisation. We explain how to use QuSpin using four detailed examples: (i) Standard exact diagonalisation of XXZ chain (ii) adiabatic ramping of parameters in the many-body localised XXZ model, (iii) heating in the periodically-driven transverse-field Ising model in a parallel field, and (iv) quantised light-atom interactions: recovering the periodically-driven atom in the semi-classical limit of a static Hamiltonian.
Momentum space Aharonov-Bohm interferometry in Rashba spin-orbit coupled Bose-Einstein condensates

The recent experimental realization of synthetic Rashba spin-orbit coupling (SOC) paves a new avenue for exploring topological phases in ultracold atoms. The unequivocal characterization of such topological physics requires a simple scheme for measuring the Berry phase originating from the SOC. Here we propose a scheme to realize momentum space Aharonov-Bohm interferometry in a Rashba spin-orbit–coupled Bose-Einstein condensate through a sudden change of the in-plane Zeeman field. We find that the π Berry phase for the Dirac point of the Rashba SOC is directly revealed by a robust dark interference fringe in the momentum space. An external perpendicular Zeeman field opens a band gap at the Dirac point, which reduces the Berry phase along the Rashba ring, leading to lower brightness of the interference fringe. We develop a variational model with semiclassical equations of motion of essential dynamical quantities for describing the interference process, yielding real and momentum space trajectories and geometric phases agreeing with the real-time simulation of the Gross-Pitaevskii equation. Our study may pave the way for the experimental detection of Berry phases in ultracold atomic systems and further exploration of momentum space interference dynamics.
Q-Gorenstein splinter rings of characteristic p are F-regular

A Noetherian integral domain R is said to be a splinter if it is a direct summand, as an R -module, of every module-finite extension ring (see [ Ma ]). In the case that R contains the field of rational numbers, it is easily seen that R is splinter if and only if it is a normal ring, but the notion is more subtle for rings of characteristic p >0. It is known that F-regular rings of characteristic p are splinters and Hochster and Huneke showed that the converse is true for locally excellent Gorenstein rings [ HH4 ]. In this paper we extend their result by showing that ℚ-Gorenstein splinters are F-regular. Our main theorem is: THEOREM 1.1. Let R be a locally excellent ℚ -Gorenstein integral domain of characteristic p>0. Then R is F-regular if and only if it is a splinter.
Interactional Processes for Stabilizing Conceptual Coherences in Physics.

Research in student knowledge and learning of science has typically focused on explaining conceptual change. Recent research, however, documents the great degree to which student thinking is dynamic and context-sensitive, implicitly calling for explanations not only of change but also of stability. In other words, when a pattern of student reasoning is sustained in specific moments and settings, what mechanisms contribute to sustaining it? We characterize student understanding and behavior in terms of multiple local coherences in that they may be variable yet still exhibit local stabilities. We attribute stability in local conceptual coherences to real-time activities that sustain these coherences. For example, particular conceptual understandings may be stabilized by the linguistic features of a worksheet question or by feedback from the students' spatial arrangement and orientation. We document a group of university students who engage in multiple local conceptual coherences while thinking about motion during a collaborative learning activity. As the students shift their thinking several times, we describe mechanisms that may contribute to local stability of their reasoning and behavior.
Collisional spin transfer in an atomic heteronuclear spinor Bose gas

This work studies heteronuclear spinor gases and characterizes the collision channels that can transfer magnetization from one element to another, using spin relaxation from different initial states.
Supernova Pencil Beam Survey

Type Ia supernovae (SNe Ia) can be calibrated to be good standard candles at cosmological distances. We propose a supernova pencil beam survey that could yield between dozens and hundreds of SNe Ia in redshift bins of 0.1 up to z = 1.5, which would complement space-based supernova searches and enable the proper consideration of the systematic uncertainties of SNe Ia as standard candles, in particular, luminosity evolution and gravitational lensing. We simulate SNe Ia luminosities by adding weak lensing noise (using empirical fitting formulae) and scatter in SN Ia absolute magnitudes to standard candles placed at random redshifts. We show that flux averaging is powerful in reducing the combined noise due to gravitational lensing and scatter in SN Ia absolute magnitudes. The supernova number count is not sensitive to matter distribution in the universe; it can be used to test models of cosmology or to measure the supernova rate. The supernova pencil beam survey can yield a wealth of data which should enable accurate determination of the cosmological parameters and the supernova rate, and provide valuable information on the formation and evolution of galaxies. The supernova pencil beam survey can be accomplished on a dedicated 4 m telescope with a square degree field of view. This telescope can be used to conduct other important observational projects compatible with the supernova pencil beam survey, such as QSOs, Kuiper belt objects, and, in particular, weak lensing measurements of field galaxies, and the search for gamma-ray burst afterglows.
Star formation at the twilight of the dark ages: Which stars reionized the universe?

We calculate the global star formation rate density (SFRD) from z ~ 30-3 using a semianalytic model incorporating the hierarchical assembly of dark matter halos, gas cooling via atomic hydrogen, star formation, supernova feedback, and suppression of gas collapse in small halos due to the presence of a photoionizing background. We compare the results with the predictions of simpler models based on the rate of dark matter halo growth and a fixed ratio of stellar to dark mass, and with observational constraints on the SFRD at 3 z 6. We also estimate the star formation rate due to very massive, metal-free Population III stars using a simple model based on the halo formation rate, calibrated against detailed hydrodynamic simulations of Population III star formation. We find that the total production rate of hydrogen-ionizing photons during the probable epoch of reionization (15 z 20) is approximately equally divided between Population II and Population III stars, and that if reionization is late (zreion 15, close to the lower limit of the range allowed by the Wilkinson Microwave Anisotropy Probe results), then Population II stars alone may be able to reionize the universe.
Analytical model for laser-assisted recombination of hydrogenic atoms

We introduce a new method that allows one to obtain an analytical cross section for the laser-assisted electron–ion collision in a closed form. As an example, we perform a calculation for the hydrogen laser-assisted recombination. The S-matrix element for the process is constructed from an exact electron Coulomb–Volkov wavefunction and an approximate laser-modified hydrogen state. An explicit expression for the field-enhancement coefficient of the process is expressed in terms of the dimensionless parameter κ = |ee0/qω0|2, where e and q are the electron charge and momentum, respectively, and e0 and ω0 are the amplitude and frequency of the laser field, respectively. The simplified version of the cross section of the process is derived and analyzed within a soft photon approximation.
Chapter Captor: Text Segmentation in Novels

Books are typically segmented into chapters and sections, representing coherent sub-narratives and topics. We investigate the task of predicting chapter boundaries, as a proxy for the general task of segmenting long texts. We build a Project Gutenberg chapter segmentation data set of 9,126 English novels, using a hybrid approach combining neural inference and rule matching to recognize chapter title headers in books, achieving an F1-score of 0.77 on this task. Using this annotated data as ground truth after removing structural cues, we present cut-based and neural methods for chapter segmentation, achieving a F1-score of 0.453 on the challenging task of exact break prediction over book-length documents. Finally, we reveal interesting historical trends in the chapter structure of novels.
Hadronic parity violation on the lattice

Abstract We motivate lattice QCD studies of the parity-violating pion–nucleon coupling constant and extend flavor-conserving hadronic parity violation from QCD to partially quenched QCD. The parity-violating pion–nucleon coupling and the anapole form factor (and moment) of the proton are computed to one-loop order in the partially quenched chiral expansion. For the parity-violating pion–nucleon interaction, we include the contributions from total derivative operators necessary to match the kinematics that will be used in lattice simulations.
The biological big bang: the first oceans of primordial planets at 2-8 million years explain Hoyle/Wickramasinghe cometary panspermia

Hydrogravitional-dynamics (HGD) cosmology of Gibson/Schild 1996 predicts that the primordial H-He4 gas of big bang nucleosynthesis became proto-globular-star-cluster clumps of Earth-mass planets at 300 Kyr. The first stars formed from mergers of these 3000 K gas planets. Chemicals C, N, O, Fe etc. created by stars and supernovae then seeded many of the reducing hydrogen gas planets with oxides to give them hot water oceans with metallic iron-nickel cores. Water oceans at critical temperature 647 K then hosted the first organic chemistry and the first life, distributed to the 1080 planets of the cosmological big bang by comets produced by the new (HGD) planet-merger star formation mechanism. The biological big bang scenario occurs between 2 Myr when liquid oceans condensed and 8 Myr when they froze. HGD cosmology explains, very naturally, the Hoyle/Wickramasinghe concept of cometary panspermia by giving a vast, hot, nourishing, cosmological primordial soup for abiogenesis, and the means for transmitting the resulting life forms and their evolving chemical mechanisms widely throughout the universe. A primordial astrophysical basis is provided for astrobiology by HGD cosmology. Concordance ΛCDMHC cosmology is rendered obsolete by the observation of complex life on Earth.