cssi/SciSciGPT-SciSciNet huggingface dataset:
A circuit model of auditory cortex

The mammalian sensory cortex is composed of multiple types of inhibitory and excitatory neurons, which form sophisticated microcircuits for processing and transmitting sensory information. Despite rapid progress in understanding the function of distinct neuronal populations, the parameters of connectivity that are required for the function of these microcircuits remain unknown. Recent studies found that two most common inhibitory interneurons, parvalbumin- (PV) and somatostatin-(SST) positive interneurons control sound-evoked responses, temporal adaptation and network dynamics in the auditory cortex (AC). These studies can inform our understanding of parameters for the connectivity of excitatory-inhibitory cortical circuits. Specifically, we asked whether a common microcircuit can account for the disparate effects found in studies by different groups. By starting with a cortical rate model, we find that a simple current-compensating mechanism accounts for the experimental findings from multiple groups. They key mechanisms are two-fold. First, PVs compensate for reduced SST activity when thalamic inputs are strong with less compensation when thalamic inputs are weak. Second, SSTs are generally disinhibited by reduced PV activity regardless of thalamic input strength. These roles are augmented by plastic synapses. These roles reproduce the differential effects of PVs and SSTs in stimulus-specific adaptation, forward suppression and tuning-curve adaptation, as well as the influence of PVs on feedforward functional connectivity in the circuit. This circuit exhibits a balance of inhibitory and excitatory currents that persists on stimulation. This approach brings together multiple findings from different laboratories and identifies a circuit that can be used in future studies of upstream and downstream sensory processing.
Oncology Therapeutics Targeting the Metabolism of Amino Acids

Amino acid metabolism promotes cancer cell proliferation and survival by supporting building block synthesis, producing reducing agents to mitigate oxidative stress, and generating immunosuppressive metabolites for immune evasion. Malignant cells rewire amino acid metabolism to maximize their access to nutrients. Amino acid transporter expression is upregulated to acquire amino acids from the extracellular environment. Under nutrient depleted conditions, macropinocytosis can be activated where proteins from the extracellular environment are engulfed and degraded into the constituent amino acids. The demand for non-essential amino acids (NEAAs) can be met through de novo synthesis pathways. Cancer cells can alter various signaling pathways to boost amino acid usage for the generation of nucleotides, reactive oxygen species (ROS) scavenging molecules, and oncometabolites. The importance of amino acid metabolism in cancer proliferation makes it a potential target for therapeutic intervention, including via small molecules and antibodies. In this review, we will delineate the targets related to amino acid metabolism and promising therapeutic approaches.
Hop-by-Hop Multipath Routing: Choosing the Right Nexthop Set

The Internet can be made more efficient and robust with hop-by-hop multipath routing: Each router on the path can split packets between multiple nexthops in order to 1) avoid failed links and 2) reduce traffic on congested links. Before deciding how to split traffic, one first needs to decide which nexthops to allow at each step. In this paper, we investigate the requirements and trade-offs for making this choice.Most related work chooses the viable nexthops by applying the "Downward Criterion", i.e., only adding nexthops that lead closer to the destination; or more generally by creating a Directed Acyclic Graph (DAG) for each destination. We show that a DAG’s nexthop options are necessarily limited, and that, by using certain links in both directions (per destination), we can add further nexthops while still avoiding loops. Our solution LFID (LoopFree Inport-Dependent) routing, though having a slightly higher time complexity, leads to both a higher number of and shorter potential paths than related work. LFID thus protects against a higher percentage of single and multiple failures (or congestions) and comes close to the performance of arbitrary source routing.
Emergent Flexibility in Institutional Development: How International Rules Really Change

How do formal international institutions change and adjust to new circumstances? The conventional wisdom in International Relations (IR), outlined by rational design, is that the answer lies in designed flexibility, which allows states to adjust agreements. Drawing on rich but disparate literatures across subfields of political science — especially constructivism and historical institutionalism — we propose an alternative, which we call “emergent flexibility.” Emergent flexibility is a property of international institutions that is not intentionally crafted by rule-makers when a rule is formally established, but is subsequently discovered, activated, and accessed by creative rule-users in ways unintended by designers. Rich case studies trace how rule-users have accessed emergent flexibility through the legal interpretive strategy of subsequent practice to change rigid rules of the UN Charter and the European Convention on Human Rights. A key implication of emergent flexibility is that, contrary to rational design expectations, international institutions designed to be rigid can adjust to unforeseen circumstances even in the absence of formal redesign, allowing cooperation to continue. The broadening of flexibility from designed to emergent reveals the politics of flexibility between formal design moments, provides a more nuanced notion of intentionality, and equips us to better address fundamental positive and normative questions of institutional development.
Data Oblivious Algorithms for Multicores

A data-oblivious algorithm is an algorithm whose memory access pattern is independent of the input values. We initiate the study of parallel data oblivious algorithms on realistic multicores, best captured by the binary fork-join model of computation. We present a data-oblivious CREW binary fork-join sorting algorithm with optimal total work and optimal (cache-oblivious) cache complexity, and in O(log n log log n) span (i.e., parallel time); these bounds match the best-known bounds for binary fork-join cache-efficient insecure algorithms. Using our sorting algorithm as a core primitive, we show how to data-obliviously simulate general PRAM algorithms in the binary fork-join model with non-trivial efficiency, and we present data-oblivious algorithms for several applications including list ranking, Euler tour, tree contraction, connected components, and minimum spanning forest. All of our data oblivious algorithms have bounds that either match or improve over the best known bounds for insecure algorithms. Complementing these asymptotically efficient results, we present a practical variant of our sorting algorithm that is self-contained and potentially implementable. It has optimal caching cost, and it is only a log log n factor off from optimal work and about a log n factor off in terms of span. %moreover, it achieves small constant factors in its bounds. We also present an EREW variant with optimal work and caching cost, and with the same asymptotic span.
Item Response Theory Based Ensemble in Machine Learning

In this article, we propose a novel probabilistic framework to improve the accuracy of a weighted majority voting algorithm. In order to assign higher weights to the classifiers which can correctly classify hard-to-classify instances, we introduce the item response theory (IRT) framework to evaluate the samples′ difficulty and classifiers′ ability simultaneously. We assigned the weights to classifiers based on their abilities. Three models are created with different assumptions suitable for different cases. When making an inference, we keep a balance between the accuracy and complexity. In our experiment, all the base models are constructed by single trees via bootstrap. To explain the models, we illustrate how the IRT ensemble model constructs the classifying boundary. We also compare their performance with other widely used methods and show that our model performs well on 19 datasets.
What Drives Bank Lending Spreads and Collateral Requirements in the Kyrgyz Republic

Limited access to finance and its high cost have contributed to relatively low levels of private investment and subpar growth in the Kyrgyz Republic. Interest rate spreads have moderated in recent years, but remain high from both a regional and global perspective. At the same time, collateral requirements applied by banks are onerous and also constrain the quantity of credit supplied. This paper identifies a range of factors that could lower spreads in the Kyrgyz Republic: more competition, higher capital, lower credit risk, larger loan size, lower deposit rates and external funding costs, as well as a stronger legal framework. Lower operating costs appear critical to reduce relatively higher spreads for small and medium-sized banks. At the same time, a stronger legal framework and greater transparency on borrowers’ creditworthiness would help reduce the high collateral requirements. Reforms in all these areas would support greater financial inclusion in the aftermath of the pandemic, and could thus be a key source of sustainable and inclusive growth in the Kyrgyz Republic.
On distortion of normal subgroups

We examine distortion of finitely generated normal subgroups. We show a connection between subgroup distortion and group divergence. We suggest a method computing the distortion of normal subgroups by decomposing the whole group into smaller subgroups. We apply our work to compute the distortion of normal subgroups of graph of groups and normal subgroups of right-angled Artin groups that induce infinite cyclic quotient groups. We construct normal subgroups of $${{\,\mathrm{CAT}\,}}(0)$$ groups introduced by Macura and introduce a collection of normal subgroups of right-angled Artin groups. These groups provide a rich source to study the connection between subgroup distortion and group divergence on $${{\,\mathrm{CAT}\,}}(0)$$ groups.
Clinically adaptable polymer enables simultaneous spatial analysis of colonic tissues and biofilms

Microbial influences on host cells depend upon the identities of the microbes, their spatial localization, and the responses they invoke on specific host cell populations. Multimodal analyses of both microbes and host cells in a spatially resolved fashion would enable studies into these complex interactions in native tissue environments, potentially in clinical specimens. While techniques to preserve each of the microbial and host cell compartments have been used to examine tissues and microbes separately, we endeavored to develop approaches to simultaneously analyze both compartments. Herein, we established an original method for mucus preservation using Poloxamer 407 (also known as Pluronic F-127), a thermoreversible polymer with mucus-adhesive characteristics. We demonstrate that this approach can preserve spatially-defined compartments of the mucus bi-layer in the colon and the bacterial communities within, compared with their marked absence when tissues were processed with traditional formalin-fixed paraffin-embedded (FFPE) pipelines. Additionally, antigens for antibody staining of host cells were preserved and signal intensity for 16S rRNA fluorescence in situ hybridization (FISH) was enhanced in poloxamer-fixed samples. This in turn enabled us to integrate multimodal analysis using a modified multiplex immunofluorescence (MxIF) protocol. Importantly, we have formulated Poloxamer 407 to polymerize and cross-link at room temperature for use in clinical workflows. These results suggest that the fixative formulation of Poloxamer 407 can be integrated into biospecimen collection pipelines for simultaneous analysis of microbes and host cells.
Quantitative Analysis of the Physiological Contributions of Glucose to the TCA Cycle.

Summary The nutritional source for catabolism in the tricarboxylic acid (TCA) cycle is a fundamental question in metabolic physiology. Limited by data and mathematical analysis, controversy exists. Using isotope-labeling data in vivo across several experimental conditions, we construct multiple models of central carbon metabolism and develop methods based on metabolic flux analysis (MFA) to solve for the preferences of glucose, lactate, and other nutrients used in the TCA cycle. We show that in nearly all circumstances, glucose contributes more than lactate as a substrate to the TCA cycle. This conclusion is verified in different animal strains from different studies and different administrations of 13C glucose, and is extended to multiple tissue types. Thus, this quantitative analysis of organismal metabolism defines the relative contributions of nutrient fluxes in physiology, provides a resource for analysis of in vivo isotope tracing data, and concludes that glucose is the major nutrient used in mammals.
Optical coherence tomography of developing embryonic morphology

Summary form only given. Recent advances in molecular biology techniques have permitted the site specific insertion of predetermined mutations into embryos for the investigation of normal and abnormal development. Currently, there are several imaging modalities available to observe the expression of genetic mutations, but these typically require small, transparent, or fixed specimens. Optical coherence tomography (OCT) offers the ability to image in vivo developing morphology in many of the animal models used for genetic studies. In addition, OCT has the potential to rapidly and repeatedly acquire optical histology to assess development and to identify the expression of normal and abnormal genes. Optical coherence tomography is an imaging modality that permits the in vivo investigation of biological specimens on the micron scale. The imaging technique can be thought of as an analog to ultrasound B-mode imaging except backscattering of light from biological tissue layers is detected rather than acoustic reflections. OCT incorporates a fiber-optic-based Michelson interferometer using a 1300-nm low-coherent superluminescent diode (SLD) as its light source to measure the intensity of optical backscattering from within the specimen. OCT images are shown of in vivo developing morphology from a leopard frog tadpole.
United/States: A Revolutionary History of American Statehood

Where did states come from? Almost everyone thinks that states descended immediately, originally, and directly from British colonies, while only afterward joining together as the United States. As a matter of legal history, that is incorrect. States and the United States were created by revolutionary independence, and they developed simultaneously in that context as improvised entities that were profoundly interdependent and mutually constitutive, rather than separate or sequential. “States-first” histories have provided foundational support for past and present arguments favoring states’ rights and state sovereignty. This Article gathers preconstitutional evidence about state constitutions, American independence, and territorial boundaries to challenge that historical premise. The Article also chronicles how states-first histories became a dominant cultural narrative, emerging from factually misleading political debates during the Constitution’s ratification. Accurate history matters. Dispelling myths about American statehood can change how modern lawyers think about federalism and constitutional law. This Article’s research weakens current support for “New Federalism” jurisprudence, associates states-rights arguments with periods of conspicuous racism, and exposes statehood’s functionality as an issue for political actors instead of constitutional adjudication. Flawed histories of statehood have been used for many doctrinal, political, and institutional purposes in the past. This Article hopes that modern readers might find their own use for accurate histories of statehood in the future.
Shoulder abduction loading affects motor coordination in individuals with chronic stroke, informing targeted rehabilitation

Individuals post stroke experience motor impairments, such as loss of independent joint control, weakness, and delayed movement initiation, leading to an overall reduction in arm function. Their motion becomes slower and more discoordinated, making it difficult to complete timing-sensitive tasks, such as balancing a glass of water or carrying a bowl with a ball inside it. Understanding how the stroke-induced motor impairments interact with each other can help design assisted training regimens for improved recovery. In this study, we investigate the effects of abnormal joint coupling patterns induced by flexion synergy on timing-sensitive motor coordination in the paretic upper limb. We design a virtual ball-in-bowl task that requires fast movements for optimal performance and implement it on a robotic system, capable of providing varying levels of abduction loading at the shoulder. We recruit 12 participants (6 individuals with chronic stroke and 6 unimpaired controls) and assess their skill at the task at 3 levels of loading, defined by the vertical force applied at the robot end-effector. Our results show that, for individuals with stroke, loading has a significant effect on their ability to generate quick coordinated motion. With increases in loading, their overall task performance decreases and they are less able to compensate for ball dynamics—frequency analysis of their motion indicates that abduction loading weakens their ability to generate movements at the resonant frequency of the dynamic task. This effect is likely due to an increased reliance on lower resolution indirect motor pathways in individuals post stroke. Given the inter-dependency of loading and dynamic task performance, we can create targeted robot-aided training protocols focused on improving timing-sensitive motor control, similar to existing progressive loading therapies, which have shown efficacy for expanding reachable workspace post stroke.
Adaptation, ancestral variation and gene flow in a 'Sky Island' Drosophila species.

Over time, populations of species can expand, contract, fragment and become isolated, creating subpopulations that must adapt to local conditions. Understanding how species maintain variation after divergence as well as adapt to these changes in the face of gene flow is of great interest, especially as the current climate crisis has caused range shifts and frequent migrations for many species. Here, we characterize how a mycophageous fly species, Drosophila innubila, came to inhabit and adapt to its current range which includes mountain forests in south-western USA separated by large expanses of desert. Using population genomic data from more than 300 wild-caught individuals, we examine four populations to determine their population history in these mountain forests, looking for signatures of local adaptation. In this first extensive study, establishing D. innubila as a key genomic "Sky Island" model, we find D. innubila spread northwards during the previous glaciation period (30-100 KYA) and have recently expanded even further (0.2-2 KYA). D. innubila shows little evidence of population structure, consistent with a recent establishment and genetic variation maintained since before geographic stratification. We also find some signatures of recent selective sweeps in chorion proteins and population differentiation in antifungal immune genes suggesting differences in the environments to which flies are adapting. However, we find little support for long-term recurrent selection in these genes. In contrast, we find evidence of long-term recurrent positive selection in immune pathways such as the Toll signalling system and the Toll-regulated antimicrobial peptides.
Subtle metastability of the layered magnetic topological insulator MnBi2Te4 from weak interactions

Layered quantum materials can host interesting properties, including magnetic and topological, for which enormous computational predictions have been done. Their thermodynamic stability is much less visited computationally, which however determines the existence of materials and can be used to guide experimental synthesis. MnBi2Te4 is one of such layered quantum materials that was predicted to be an intrinsic antiferromagnetic topological insulator, and later experimentally realized but in a thermodynamically metastable state. Here, using a combined first-principles-based approach that considers lattice, charge, and spin degrees of freedom, we investigate the metastability of MnBi2Te4 by calculating the Helmholtz free energy for the reaction Bi2Te3 + MnTe → MnBi2Te4. We identify a temperature range (~500–873 K) in which the compound is stable with respect to the competing binary phases, consistent with experimental observation. We validate the predictions by comparing the calculated specific heats contributed from different degrees of freedom with experimental results. Our findings indicate that the degrees of freedom responsible for the van der Waals interaction, lattice vibration, magnetic coupling, and nontrivial band topology in MnBi2Te4 not only enable emergent phenomena but also play a crucial role in determining its thermodynamic stability. This conclusion lays the foundation for the future computational material synthesis of novel layered systems.
Superstability, noetherian rings and pure-semisimple rings

Abstract We uncover a connection between the model-theoretic notion of superstability and that of noetherian rings and pure-semisimple rings. We characterize noetherian rings via superstability of the class of left modules with embeddings. Theorem 0.1 For a ring R the following are equivalent. (1) R is left noetherian. (2) The class of left R-modules with embeddings is superstable. (3) For every λ ≥ | R | + ℵ 0 , there is χ ≥ λ such that the class of left R-modules with embeddings has uniqueness of limit models of cardinality χ. (4) Every limit model in the class of left R-modules with embeddings is Σ-injective. We characterize left pure-semisimple rings via superstability of the class of left modules with pure embeddings. Theorem 0.2 For a ring R the following are equivalent. (1) R is left pure-semisimple. (2) The class of left R-modules with pure embeddings is superstable. (3) There exists λ ≥ ( | R | + ℵ 0 ) + such that the class of left R-modules with pure embeddings has uniqueness of limit models of cardinality λ. (4) Every limit model in the class of left R-modules with pure embeddings is Σ-pure-injective. Both equivalences provide evidence that the notion of superstability could shed light in the understanding of algebraic concepts. As this paper is aimed at model theorists and algebraists an effort was made to provide the background for both.
Systematizing the Effective Theory of Self-Interacting Dark Matter

If dark matter has strong self-interactions, future astrophysical and cosmological observations, together with a clearer understanding of baryonic feedback effects, might be used to extract the velocity dependence of the dark matter scattering rate. To interpret such data, we should understand what predictions for this quantity are made by various models of the underlying particle nature of dark matter. In this paper, we systematically compute this function for fermionic dark matter with light bosonic mediators of vector, scalar, axial vector, and pseudoscalar type. We do this by matching to the nonrelativistic effective theory of self-interacting dark matter and then computing the spin-averaged viscosity cross section nonperturbatively by solving the Schrodinger equation, thus accounting for any possible Sommerfeld enhancement of the low-velocity cross section. In the pseudoscalar case, this requires a coupled-channel analysis of different angular momentum modes. We find, contrary to some earlier analyses, that nonrelativistic effects only provide a significant enhancement for the cases of light scalar and vector mediators. Scattering from light pseudoscalar and axial vector mediators is well described by tree-level quantum field theory.
Absence of Replica Symmetry Breaking in the Random Field Ising Model

It is shown that replica symmetry is not broken in the random field Ising model in any dimension, at any temperature and field strength, except possibly at a measure-zero set of exceptional temperatures and field strengths.
A note on torus actions and the Witten genus

We show that the Witten genus of a string manifold $M$ vanishes, if there is an effective action of a torus $T$ on $M$ such that $\dim T>b_2(M)$. We apply this result to study group actions on $M\times G/T$, where $G$ is a compact connected Lie group and $T$ a maximal torus of $G$. Moreover, we use the methods which are needed to prove these results to the study of torus manifolds. We show that up to diffeomorphism there are only finitely many quasitoric manifolds $M$ with the same cohomology ring as $#_{i=1}^k \pm\mathbb{C} P^n$ with $k<n$.
Social insurance, demographics, and rural-urban migration in China

Abstract We develop a dynamic general equilibrium model to analyze the impact of social insurance policy and demographic changes on rural-urban migration in China. Quantitative analyses indicate that different social insurance programs not only have differential effects on net migration flows but also on the age and income distribution of migrants. Enrolling migrants in urban pensions discourages rural-urban migration at young ages and reverse migration in old-age. In contrast, urban health insurance incentivizes rural-urban migration among low income groups at all ages while simultaneously disincentivizing reverse migration. These differences subsequently have important impacts on overall migration patterns and the macroeconomy. Incorporating population aging in the model also yields an increase in the working age migrant share as higher capital accumulation maintains significant upward pressure on urban wages. Overall, results indicate that general equilibrium effects matter and demographic and policy changes alter migration incentives differently at different stages of the life-cycle.
Perspectives on Gamma-Ray Pulsar Emission

Pulsars are powerful sources of radiation across the electromagnetic spectrum. This paper highlights some theoretical insights into non‐thermal, magnetospheric pulsar gamma‐ray radiation. These advances have been driven by NASA’s Fermi mission, launched in mid‐2008. The Large Area Telescope (LAT) instrument on Fermi has afforded the discrimination between polar cap and slot gap/outer gap acceleration zones in young and middle‐aged pulsars. Altitude discernment using the highest energy pulsar photons will be addressed, as will spectroscopic interpretation of the primary radiation mechanism in the LAT band, connecting to both polar cap/slot gap and outer gap scenarios. Focuses will mostly be on curvature radiation and magnetic pair creation, including population trends that may afford probes of the magnetospheric accelerating potential.
Intelligent life in cosmology

I shall present three arguments for the proposition that intelligent life is very rare in the universe. First, I shall summarize the consensus opinion of the founders of the modern synthesis (Simpson, Dobzhanski and Mayr) that the evolution of intelligent life is exceedingly improbable. Secondly, I shall develop the Fermi paradox: if they existed, they would be here. Thirdly, I shall show that if intelligent life were too common, it would use up all available resources and die out. But I shall show that the quantum mechanical principle of unitarity (actually a form of teleology!) requires intelligent life to survive to the end of time. Finally, I shall argue that, if the universe is indeed accelerating, then survival to the end of time requires that intelligent life, though rare, to have evolved several times in the visible universe. I shall argue that the acceleration is a consequence of the excess of matter over antimatter in the universe. I shall suggest experiments to test these claims.
Degeneration of dynamical degrees in families of maps

The dynamical degree of a dominant rational map $f:\mathbb{P}^N\rightarrow\mathbb{P}^N$ is the quantity $\delta(f):=\lim(\text{deg} f^n)^{1/n}$. We study the variation of dynamical degrees in 1-parameter families of maps $f_T$. We make a conjecture and ask two questions concerning, respectively, the set of $t$ such that: (1) $\delta(f_t)\le\delta(f_T)-\epsilon$; (2) $\delta(f_t)<\delta(f_T)$; (3) $\delta(f_t)<\delta(f_T)$ and $\delta(g_t)<\delta(g_T)$ for "independent" families of maps. We give a sufficient condition for our conjecture to hold and prove that it is true for monomial maps. We describe non-trivial families of maps for which our questions have affirmative and negative answers.
Difference integrability conditions for parameterized linear difference and differential equations

This paper is devoted to integrability conditions for systems of linear difference and differential equations with difference parameters. It is shown that such a system is difference isomonodromic if and only if it is difference isomonodromic with respect to each parameter separately. Due to this result, it is no longer necessary to solve non-linear difference equations to verify isomonodromicity, which will improve efficiency of computation with these systems.
Topological Insulators with Ultracold Atoms

Ultracold atom research presents many avenues to study problems at the forefront of physics. Due to their unprecedented controllability, these systems are ideally suited to explore new exotic states of matter, which is one of the key driving elements of the condensed matter research. One such topic of considerable importance is topological insulators, materials that are insulating in the interior but conduct along the edges. Quantum Hall and its close cousin Quantum Spin Hall states belong to the family of these exotic states and are the subject of this chapter.
Extinction in four species cyclic competition

When four species compete stochastically in a cyclic way, the formation of two teams of mutually neutral partners is observed. In this paper we study through numerical simulations the extinction processes that can take place in this system both in the well mixed case as well as on different types of lattices. The different routes to extinction are revealed by the probability distribution of the domination time, i.e.?the time needed for one team to fully occupy the system. If swapping is allowed between neutral partners, then the probability distribution is dominated by very long-lived states where a few very large domains persist, each domain being occupied by a mix of individuals from species that form one of the teams. Many aspects of the possible extinction scenarios are lost when only considering averaged quantities, such as for example the mean domination time.
The Transient Responses of an Axisymmetric Tropical Cyclone to Instantaneous Surface Roughening and Drying

AbstractInland tropical cyclone (TC) impacts due to high winds and rainfall-induced flooding depend strongly on the evolution of the wind field and precipitation distribution after landfall. Howeve...
Ising model with a boundary magnetic field — an example of a boundary flow

In [1] a nonperturbative proof of the g-theorem of Affleck and Ludwig was put forward. In this paper we illustrate how the proof of [1] works on the example of the 2D Ising model at criticality perturbed by a boundary magnetic field. For this model we present explicit computations of all the quantities entering the proof including various contact terms. A free massless boson with a boundary mass term is considered as a warm-up example.
Ternary plots for neutrino mixing visualization

The visualization advantages of ternary plots are illustrated for the PMNS neutrino mixing matrix. Unitarity constraints are incorporated automatically, in part, since barycentric plots of this type allow three variables with a fixed sum to be plotted as mere points inside an equilateral triangle on a plane.
Probing Late-type T Dwarf J - H Color Outliers for Signs of Age

We present the results of a Keck/NIRSPEC follow-up survey of thirteen late-type T dwarfs (T6-T9), twelve of which have unusually red or blue J-H colors. Previous work suggests that J-H color outliers may represent the high-gravity, low-metallicity (old) and low-gravity, solar-metallicity (young) extremes of the late-type T dwarf population. We use medium-resolution Y- and H-band spectroscopy to probe regions of T dwarf atmospheres that are more sensitive to gravity and metallicity variations than the J band. We find that the spectral morphologies of our sample are largely homogeneous, with peak-normalized, Y- and H-band morphologies consistent with spectral standards. However, three objects stand out as potentially old, with overluminous Y-band spectra compared to their respective spectral standards, and a fourth object stands out as potentially young, with an underluminous Y band. Of these four objects, three have been previously identified as potential metallicity/gravity outliers, including the one object in our sample with a normal J-H color. We fit publicly available atmospheric model grids to our spectra and find that the best-fit physical parameters vary depending on the model used. As we continue to probe the characteristics of the late-T population, differences in synthetic spectra of ~10-20% in the blue wing of the Y band and ~45% at 1.65 microns, for the same physical parameters, must be reconciled. Further development and public availability of nonsolar metallicity models is also recommended. Future progress toward deciphering the impacts of gravity, metallicity, and variability in the late-type T dwarf population will also require high signal-to-noise, multiwavelength and multi-epoch photometry and spectroscopy.
Cooperative Energy Harvesting Networks With Spatially Random Users

This letter considers a cooperative network with multiple source-destination pairs and one energy harvesting relay. The outage probability experienced by users in this network is characterized by taking the spatial randomness of user locations into consideration. In addition, the cooperation among users is modeled as a canonical coalitional game and the grand coalition is shown to be stable in the addressed scenario. Simulation results are provided to demonstrate the accuracy of the developed analytical results.
Standard Model Higgs boson searches at the Tevatron

We give an overview of Standard Model (SM) Higgs boson studies performed at the CDF and D∅ experiments at the Tevatron proton–antiproton collider. Combining the results of many individual analyses, most of which use the full data set available, an excess with a significance of 3.0 standard deviations with respect to the SM hypothesis is observed at a Higgs boson mass of 125 GeV/c2. At that mass, the combined best-fit cross-section is consistent with the SM prediction. Constraints are also placed on the Higgs boson couplings with fermions and electroweak vector bosons and are consistent with the SM predictions within the uncertainties.
THE EB FACTORY PROJECT. I. A FAST, NEURAL-NET-BASED, GENERAL PURPOSE LIGHT CURVE CLASSIFIER OPTIMIZED FOR ECLIPSING BINARIES

We describe a new neural-net-based light curve classifier and provide it with documentation as a ready-to-use tool for the community. While optimized for identification and classification of eclipsing binary stars, the classifier is general purpose, and has been developed for speed in the context of upcoming massive surveys such as the Large Synoptic Survey Telescope. A challenge for classifiers in the context of neural-net training and massive data sets is to minimize the number of parameters required to describe each light curve. We show that a simple and fast geometric representation that encodes the overall light curve shape, together with a chi-square parameter to capture higher-order morphology information results in efficient yet robust light curve classification, especially for eclipsing binaries. Testing the classifier on the ASAS light curve database, we achieve a retrieval rate of 98% and a false-positive rate of 2% for eclipsing binaries. We achieve similarly high retrieval rates for most other periodic variable-star classes, including RR Lyrae, Mira, and delta Scuti. However, the classifier currently has difficulty discriminating between different sub-classes of eclipsing binaries, and suffers a relatively low (∼60%) retrieval rate for multi-mode delta Cepheid stars. We find that it is imperative to train the classifier'smore » neural network with exemplars that include the full range of light curve quality to which the classifier will be expected to perform; the classifier performs well on noisy light curves only when trained with noisy exemplars. The classifier source code, ancillary programs, a trained neural net, and a guide for use, are provided.« less
CONSTRAINTS ON THE SIZE OF EXTRA DIMENSIONS FROM THE ORBITAL EVOLUTION OF BLACK-HOLE X-RAY BINARIES

One of the plausible unification schemes in physics considers the observable universe to be a four-dimensional surface (the brane) embedded in a higher dimensional curved spacetime (the bulk). In such braneworld gravity models with infinitely large extra dimensions, black holes evaporate fast through the emission of the additional gravitational degrees of freedom, resulting in lifetimes of stellar-mass black holes that are significantly smaller than the Hubble time. We show that the predicted evaporation rate leads to a change in the orbital period of X-ray binaries harboring black holes that is observable with current instruments. We obtain an upper limit on the rate of change of the orbital period of the binary A0620–00 and use it to constrain the asymptotic curvature radius of the extra dimension to a value comparable to the one obtained by table-top experiments. Furthermore, we argue that any measurement of a period increase for low-mass X-ray binaries with a high mass ratio is evidence for new physics beyond general relativity and the standard model.
CHARACTERIZATION OF KEPLER-91B AND THE INVESTIGATION OF A POTENTIAL TROJAN COMPANION USING EXONEST

Presented here is an independent re-analysis of the Kepler light curve of Kepler-91 (KIC 8219268). Using the EXONEST software package, which provides both Bayesian parameter estimation and Bayesian model testing, we were able to re-confirm the planetary nature of Kepler-91b. In addition to the primary and secondary eclipses of Kepler-91b, a third dimming event appears to occur approximately $60^o$ away (in phase) from the secondary eclipse, leading to the hypothesis that a Trojan planet may be located at the L4 or L5 Lagrange points. Here, we present a comprehensive investigation of four possibilities to explain the observed dimming event using all available photometric data from the Kepler Space Telescope, recently obtained radial velocity measurements, and N-body simulations. We find that the photometric model describing Kepler-91b and a Trojan planet is highly favored over the model involving Kepler-91b alone. However, it predicts an unphysically high temperature for the Trojan companion, leading to the conclusion that the extra dimming event is likely a false-postive.
PRECISE ABSOLUTE ASTROMETRY FROM THE VLBA IMAGING AND POLARIMETRY SURVEY AT 5 GHz

We present accurate positions for 857 sources derived from the astrometric analysis of 16 eleven-hour experiments from the Very Long Baseline Array imaging and polarimetry survey at 5 GHz (VIPS). Among the observed sources, positions of 430 objects were not previously determined at milliarcsecond-level accuracy. For 95% of the sources the uncertainty of their positions ranges from 0.3 to 0.9 mas, with a median value of 0.5 mas. This estimate of accuracy is substantiated by the comparison of positions of 386 sources that were previously observed in astrometric programs simultaneously at 2.3/8.6 GHz. Surprisingly, the ionosphere contribution to group delay was adequately modeled with the use of the total electron content maps derived from GPS observations and only marginally affected estimates of source coordinates.
The Lorentzian inversion formula and the spectrum of the 3d O(2) CFT

We study the spectrum and OPE coefficients of the three-dimensional critical O(2) model, using four-point functions of the leading scalars with charges 0, 1, and 2 (s, ϕ, and t). We obtain numerical predictions for low-twist OPE data in several charge sectors using the extremal functional method. We compare the results to analytical estimates using the Lorentzian inversion formula and a small amount of numerical input. We find agreement between the analytic and numerical predictions. We also give evidence that certain scalar operators lie on double-twist Regge trajectories and obtain estimates for the leading Regge intercepts of the O(2) model.
Multi-Modal Non-Line-of-Sight Passive Imaging

We consider the non-line-of-sight (NLOS) imaging of an object using the light reflected off a diffusive wall. The wall scatters incident light such that a lens is no longer useful to form an image. Instead, we exploit the 4D spatial coherence function to reconstruct a 2D projection of the obscured object. The approach is completely passive in the sense that no control over the light illuminating the object is assumed and is compatible with the partially coherent fields ubiquitous in both the indoor and outdoor environments. We formulate a multi-criteria convex optimization problem for reconstruction, which fuses the reflected field’s intensity and spatial coherence information at different scales. Our formulation leverages established optics models of light propagation and scattering and exploits the sparsity common to many images in different bases. We also develop an algorithm based on the alternating direction method of multipliers to efficiently solve the convex program proposed. A means for analyzing the null space of the measurement matrices is provided as well as a means for weighting the contribution of individual measurements to the reconstruction. This paper holds promise to advance passive imaging in the challenging NLOS regimes in which the intensity does not necessarily retain distinguishable features and provides a framework for multi-modal information fusion for efficient scene reconstruction.
A restriction on the Alexander polynomials of L-space knots

Using an invariant defined by Rasmussen, we extend an argument given by Hedden and Watson which further restricts which Alexander polynomials can be realized by $L$-space knots.
Universal variations of Hodge structure and Calabi-Yau-Schottky relations

Varieties generally come to life through the maps between them and the modules (e.g. functions) that live on them. Moduli spaces are no exception to this rule. An important class of maps on moduli spaces (for compact Kahler manifolds) is that of period maps, which are substantially the same thing as the modules known as variations of Hodge structure. The purpose of this paper is twofold. First, we give a canonical formula for the variation of Hodge structure associated to the m-th order universal deformation of an arbitrary compact Kahler manifold without vector fields. Second, we specialize to the case of a Calabi-Yau manifold X where we give a formula for the m-th differential of the period map of X and deduce formal defining equations for its image (Schottky relations); these are (necessarily infinite, in dimension ≥ 3) power series in the middle cohomology. We will use the method of canonical infinitesimal deformations, developed by the author in earlier papers [R1, R2]. This method gives a canonical description of infinitesimal moduli spaces and, what’s more, natural maps involving them. While it might be argued that a germ of a smooth space-such as the moduli of an unobstructed manifold-is a rather rigid featureless object, making a canonical description of it uninteresting, on the contrary maps involving such germs can be quite interesting; in the case of moduli, the method of canonical infinitesimal deformations provides a vehicle for studying such maps. For instance in the case at hand the m-th derivative of the period map of Calabi-Yau n-fold X is a filtered map T X M → H DR(X)/F whose associated gradeds SH(TX) → Hn−i,i X are the so-called YukawaGreen forms (cf. [G]). We will develop cohomological formulas for this and other derivative maps (Theorems 4.1, 4.3 below), which will allow us to determine their image and derive (Schottky) relations defining this image, essentially in terms of some generalized Yukawa-Green type forms (Theorem 4.1, Corollary 4.4) . For n = 2 we recover the celebrated ’period quadric’ of K3 surface theory; for n ≥ 3 the relations seem to be new. For n = 3 this situation is particularly interesting assuming the ’mirror conjecture’ because then the higher derivatives of the period map, here computed, are related -in fact, carry equivalent information tothe ’quantum cohomology’(esp. numbers of rational curves, etc.) of the mirror of X. We hope to return to this in greater detail elsewhere. The present methods should be applicable in other Schottky-type problems: the case of curves has been developed by G. Liu ( UCR dissertation 1997). This paper is a revised version of a manuscript entitled ’linear structure on Calabi-Yau moduli spaces’ (May 1993). We are grateful to Professors P. Deligne and M. Green for some enlightening comments early on. We are especially grateful
Mocking the weak lensing universe: The LensTools Python computing package

Abstract We present a newly developed software package which implements a wide range of routines frequently used in Weak Gravitational Lensing (WL). With the continuously increasing size of the WL scientific community we feel that easy to use Application Program Interfaces (APIs) for common calculations are a necessity to ensure efficiency and coordination across different working groups. Coupled with existing open source codes, such as CAMB (Lewis et al., 2000) and Gadget2 (Springel, 2005), LensTools brings together a cosmic shear simulation pipeline which, complemented with a variety of WL feature measurement tools and parameter sampling routines, provides easy access to the numerics for theoretical studies of WL as well as for experiment forecasts. Being implemented in python (Rossum, 1995), LensTools takes full advantage of a range of state-of-the art techniques developed by the large and growing open-source software community (Jones et al., 2001; McKinney, 2010; Astrophy Collaboration, 2013; Pedregosa et al., 2011; Foreman-Mackey et al., 2013). We made the LensTools code available on the Python Package Index and published its documentation on http://lenstools.readthedocs.io .
A SMALL BUT NONZERO COSMOLOGICAL CONSTANT

Recent astrophysical observations seem to indicate that the cosmological constant is small but nonzero and positive. The old cosmological constant problem asks why it is so small; we must now ask, in addition, why it is nonzero (and is in the range found by recent observations), and why it is positive. In this essay, we try to kill these three metaphorical birds with one stone. That stone is the unimodular theory of gravity, which is the ordinary theory of gravity, except for the way the cosmological constant arises in the theory. We argue that the cosmological constant becomes dynamical, and eventually, in terms of the cosmic scale factor R(t), it takes the form Λ(t)=Λ(t0)(R(t0)/R(t))2, but not before the epoch corresponding to the redshift parameter z~1.
Constant-speed ramps

It is easy to show that if the kinetic coefficient of friction between a block and a ramp is k and this ramp is a straight line with slope k, then this block will move along the ramp with constant speed. A natural question to ask is the following: besides straight lines, are there other shapes of ramps such that a block will go down the ramp with constant speed? Here we classify all possible shapes of these ramps, and, surprisingly, we show that the planar ramps can be parametrized in terms of elementary functions: trigonometric functions, exponential functions and their inverses. They provide basic examples of curves explicitly parametrized by arclength. A video explaining the main results in this paper can be found at http://youtu.be/iBrvbb0efVk.