cssi/SciSciGPT-SciSciNet huggingface dataset:
An Optimal Transport Formulation of the Ensemble Kalman Filter

Controlled interacting particle systems such as the ensemble Kalman filter (EnKF) and the feedback particle filter (FPF) are numerical algorithms to approximate the solution of the nonlinear filtering problem in continuous time. The distinguishing feature of these algorithms is that the Bayesian update step is implemented using a feedback control law. It has been noted in the literature that the control law is not unique. This is the main problem addressed in this article. To obtain a unique control law, the filtering problem is formulated here as an optimal transportation problem. An explicit formula for the (mean-field type) optimal control law is derived in the linear Gaussian setting. Comparisons are made with the control laws for different types of EnKF algorithms described in the literature. Via empirical approximation of the mean-field control law, a finite- $N$ controlled interacting particle algorithm is obtained. For this algorithm, the equations for empirical mean and covariance are derived and shown to be identical to the Kalman filter. This allows strong conclusions on convergence and error properties based on the classical filter stability theory for the Kalman filter. It is shown that, under certain technical conditions, the mean squared error converges to zero even with a finite number of particles. A detailed propagation of chaos analysis is carried out for the finite- $N$ algorithm. The analysis is used to prove weak convergence of the empirical distribution as $N\rightarrow \infty$ . For a certain simplified filtering problem, analytical comparison of the mse with the importance sampling-based algorithms is described. The analysis helps explain the favorable scaling properties of the control-based algorithms reported in several numerical studies in recent literature.
Data market platforms: trading data assets to solve data problems

Data only generates value for a few organizations with expertise and resources to make data shareable, discoverable, and easy to integrate. Sharing data that is easy to discover and integrate is hard because data owners lack information (who needs what data) and they do not have incentives to prepare the data in a way that is easy to consume by others.In this paper, we propose data market platforms to address the lack of information and incentives and tackle the problems of data sharing, discovery, and integration. In a data market platform, data owners want to share data because they will be rewarded if they do so. Consumers are encouraged to share their data needs because the market will solve the discovery and integration problem for them in exchange for some form of currency.We consider internal markets that operate within organizations to bring down data silos, as well as external markets that operate across organizations to increase the value of data for everybody. We outline a research agenda that revolves around two problems. The problem of market design, or how to design rules that lead to desired outcomes, and the systems problem, how to implement the market and enforce the rules. Treating data as a first-class asset is sorely needed to extend the value of data to more organizations, and we propose data market platforms as one mechanism to achieve this goal.
Influenza C and D viral load in cattle correlates with bovine respiratory disease (BRD): Emerging role of orthomyxoviruses in the pathogenesis of BRD.

Bovine respiratory disease (BRD) is the costliest disease affecting the cattle industry globally. Orthomyxoviruses, influenza C virus (ICV) and influenza D virus (IDV) have recently been implicated to play a role in BRD. However, there are contradicting reports about the association of IDV and ICV to BRD. Using the largest cohort study (cattle, n = 599) to date we investigated the association of influenza viruses in cattle with BRD. Cattle were scored for respiratory symptoms and pooled nasal and pharyngeal swabs were tested for bovine viral diarrhea virus, bovine herpesvirus 1, bovine respiratory syncytial virus, bovine coronavirus, ICV and IDV by real-time PCR. Cattle that have higher viral loads of IDV and ICV also have greater numbers of co-infecting viruses than controls. More strikingly, 2 logs higher IDV viral RNA in BRD-symptomatic cattle that are co-infected animals than those infected with IDV alone. Our results strongly suggest that ICV and IDV may be significant contributors to BRD.
Car restriction policies for better urban health: a low emission zone in Madrid, Spain

The design of most cities prioritizes the use of motorized vehicles, having a negative effect on urban health. A major concern in the European Union (EU) is air pollution, especially nitrogen dioxide (NO2), which causes many inhabitants health problems and decreases the quality of life. A non-expensive way to reduce pollutants is implementing road restriction policies, as the creation of low emission zones. In this work, we analyze the case of Madrid Central, a low emission zone deployed in Madrid, Spain. We evaluate if it was effective to reduce air pollutants and if there were a side effect, as pollution displacement, during its application. Drawing on open data, we analyze air quality at different points of the city, before and during the application of this measure. Taking into account the EU directives in terms of what healthy air means, we consider three metrics: (a) the trend of NO2 concentration in the air in both periods, (b) the difference between the NO2 concentration during both periods, and (c) the percentage of time in which the population is exposed to air with NO2 concentration under a specific threshold (healthy air as defined by the EU). According to the results, Madrid Central significantly reduces the NO2 concentration in the air and does not produce pollution displacement. Thus, the population breathes healthy air during more time, and there is a positive effect on the whole city.
Planning for the Unexpected: Explicitly Optimizing Motions for Ground Uncertainty in Running

We propose a method to generate actuation plans for a reduced order, dynamic model of bipedal running. This method explicitly enforces robustness to ground uncertainty. The plan generated is not a fixed body trajectory that is aggressively stabilized: instead, the plan interacts with the passive dynamics of the reduced order model to create emergent robustness. The goal is to create plans for legged robots that will be robust to imperfect perception of the environment, and to work with dynamics that are too complex to optimize in real-time. Working within this dynamic model of legged locomotion, we optimize a set of disturbance cases together with the nominal case, all with linked inputs. The input linking is nontrivial due to the hybrid dynamics of the running model but our solution is effective and has analytical gradients. The optimization procedure proposed is significantly slower than a standard trajectory optimization, but results in robust gaits that reject disturbances extremely effectively without any replanning required.
The role of the ocular tissue in sars-cov-2 transmission

The current global pandemic of coronavirus disease 2019 (COVID-19) has affected over 21 million people and caused over half a million deaths within a few months. COVID-19 has become one of the most severe public health crises in recent years. Compared to other pathogenic coronaviruses, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly infectious. Due to the lack of specific and effective treatment or vaccines, disease prevention and early detection are essential for establishing guidelines to mitigate further spread. The potential role of the ocular system in COVID-19 is still not clear but it has gained increasing attention. Here, we reviewed both clinical and research evidence on the ocular manifestations associated with COVID-19, the presence of SARS-CoV-2 in ocular surface tissues and tears, and the potential role of the eye in contracting SARS-CoV-2.
Presence and Distress of Chemotherapy-Induced Peripheral Neuropathy Symptoms in Upper Extremities of Younger and Older Breast Cancer Survivors.

Purpose The purposes of this study were to determine whether the presence of upper extremity chemotherapy-induced peripheral neuropathy (CIPN) symptoms (burning, pins/needles, numbness, pain, and skin crawls) among breast cancer survivors (BCS) varied according to age (≤45 years or 55-70 years) and to examine age group differences in upper extremity CIPN symptom distress. Methods The study was a secondary analysis of younger (n=505) and older (n=622) BCS. Inclusion criteria were age of ≤45 years or 55-70 years; patient at 3-8 years postdiagnosis; patient received the chemotherapy regimen of paclitaxel, doxorubicin, and cyclophosphamide; and patient did not have recurrence. The Symptom Survivor Checklist was used to assess presence and distress of upper extremity CIPN symptoms. Analyses explored whether age group predicted CIPN symptom presence and distress while controlling for sociodemographic and medical variables. Results Older BCS reported fewer pins/needles, numbness, and pain symptoms (odds ratios: 0.623-0.751). Heart disease (odds ratios: 1.59-1.70) and progesterone-negative breast cancer (odds ratio: 0.663) were significantly associated with one or more CIPN symptoms. Symptom distress ratings did not differ by age groups; both age groups indicated distress from CIPN symptoms, with 25% or more reporting distress as "moderately" or "quite a bit." Conclusions Younger BCS reported more upper extremity CIPN symptoms. BCS in both groups continued to report bothersome CIPN symptoms years after treatment. Study findings will assist clinicians in identifying BCS at higher risk for upper extremity CIPN as well as inform development of appropriate tailored interventions to mitigate these symptoms and facilitate restoration to age-related baseline function, thereby improving quality of life for BCS.
Scattering for defocusing energy subcritical nonlinear wave equations

We consider the Cauchy problem for the defocusing power-type nonlinear wave equation in ( 1 + 3 ) -dimensions for energy subcritical powers p in the superconformal range 3 < p < 5 . We prove that any solution is global-in-time and scatters to free waves in both time directions as long as its critical Sobolev norm stays bounded on the maximal interval of existence.
Hydrodynamic interactions of spherical particles in suspensions confined between two planar walls

Hydrodynamic interactions in a suspension of spherical particles confined between two parallel planar walls are studied under creeping-flow conditions. The many-particle friction matrix in this system is evaluated using our novel numerical algorithm based on transformations between Cartesian and spherical representations of Stokes flow. The cartesian representation is used to describe the interaction of the fluid with the walls and the spherical representation is used to describe the interaction with the particles. The transformations between these two representations are given in a closed form, which allows us to evaluate the coefficients in linear equations for the induced-force multipoles on particle surfaces. the friction matrix is obtained from these equations, supplemented with the superposition lubrication corrections. we have used our algorithm to evaluate the friction matrix for a single sphere, a pair of spheres, and for linear chains of spheres. The friction matrix exhibits a crossover from a quasi-two-dimensional behaviour (for systems with small wall separation H) to THE three-dimensional behaviour (when the distance H is much larger than the interparticle distance L). the crossover is especially pronounced for a long chain moving in the direction normal to its orientation and parallel to the walls. in this configuration, a large pressure build-up occurs in front of the chain for small values of the gapwidth H, which results in a large hydrodynamic friction force. a standard wall superposition approximation does not capture this behaviour.
Optimal stirring strategies for passive scalar mixing

We address the challenge of optimal incompressible stirring to mix an initially inhomogeneous distribution of passive tracers. As a quantitative measure of mixing we adopt the H−1 norm of the scalar fluctuation field, equivalent to the (square root of the) variance of a low-pass filtered image of the tracer concentration field. First we establish that this is a useful gauge even in the absence of molecular diffusion: its vanishing as t → ∞ is evidence of the stirring flow's mixing properties in the sense of ergodic theory. Then we derive absolute limits on the total amount of mixing, as a function of time, on a periodic spatial domain with a prescribed instantaneous stirring energy or stirring power budget. We subsequently determine the flow field that instantaneously maximizes the decay of this mixing measure – when such a flow exists. When no such ‘steepest descent’ flow exists (a possible but non-generic situation), we determine the flow that maximizes the growth rate of the H−1 norm's decay rate. This local-in-time optimal stirring strategy is implemented numerically on a benchmark problem and compared to an optimal control approach using a restricted set of flows. Some significant challenges for analysis are outlined.
Universal Series for Hilbert Schemes and Strange Duality

We show how the "finite Quot scheme method" applied to Le Potier's strange duality on del Pezzo surfaces leads to conjectures (valid for all smooth complex projective surfaces) relating two sets of universal power series on Hilbert schemes of points on surfaces: those for top chern classes of tautological sheaves, and those for Euler characteristics of line bundles. We have verified these predictions computationally for low order. We then give an analysis of these conjectures in small ranks. We also give a combinatorial proof of a formula predicted by our conjectures: the top chern class of the tautological sheaf on $S^{[n]}$ associated to the structure sheaf of a point is equal to $(-1)^n$ times the $n$th Catalan number.
Chern-Simons EM-flation

We propose a new, generic mechanism of inflation mediated by a balance between potential forces and a Chern-Simons interaction. Such quasi-topological interactions are ubiquitous in string theory. In the minisuperspace approximation, their effect on the dynamics can be mapped onto the problem of a charged particle in an electromagnetic field together with an external potential; slow roll arises when the motion is dominated by the analogue of ‘magnetic drift’. This mechanism permits inflation to proceed even in the presence of generic, steep scalar potentials. We suggest a possible experimental signature which, if observed, might be considered strong evidence for string theory.
INTERSTELLAR CN AND CH+ IN DIFFUSE MOLECULAR CLOUDS: 12C/13C RATIOS AND CN EXCITATION*

We present very high signal-to-noise ratio absorption-line observations of CN and CH+ along 13 lines of sight through diffuse molecular clouds. The data are examined to extract precise isotopologic ratios of 12CN/13CN and 12CH+/13CH+ in order to assess predictions of diffuse cloud chemistry. Our results on 12CH+/13CH+ confirm that this ratio does not deviate from the ambient 12C/13C ratio in local interstellar clouds, as expected if the formation of CH+ involves nonthermal processes. We find that 12CN/13CN, however, can be significantly fractionated away from the ambient value. The dispersion in our sample of 12CN/13CN ratios is similar to that found in recent surveys of 12CO/13CO. For sight lines where both ratios have been determined, the 12CN/13CN ratios are generally fractionated in the opposite sense compared to 12CO/13CO. Chemical fractionation in CO results from competition between selective photodissociation and isotopic charge exchange (ICE). An inverse relationship between 12CN/13CN and 12CO/13CO follows from the coexistence of CN and CO in diffuse cloud cores. However, an ICE reaction with CN may mitigate the enhancements in 12CN/13CN for lines of sight with low 12CO/13CO ratios. For two sight lines with high values of 12CO/13CO, our results indicate that about 50% of the carbon is locked up in CO, which is consistent with the notion that these sight lines probe molecular cloud envelopes where the transition from C+ to CO is expected to occur. An analysis of CN rotational excitation yields a weighted mean value for T 01(12CN) of 2.754 ± 0.002 K, which implies an excess over the temperature of the cosmic microwave background (CMB) of only 29 ± 3 mK. This modest excess eliminates the need for a local excitation mechanism beyond electron and neutral collisions. The rotational excitation temperatures in 13CN show no excess over the temperature of the CMB.
False discovery rates in somatic mutation studies of cancer

The purpose of cancer genome sequencing studies is to determine the nature and types of alterations present in a typical cancer and to discover genes mutated at high frequencies. In this article we discuss statistical methods for the analysis of somatic mutation frequency data generated in these studies. We place special emphasis on a two-stage study design introduced by Sjoblom et al. [Science 314 (2006) 268–274]. In this context, we describe and compare statistical methods for constructing scores that can be used to prioritize candidate genes for further investigation and to assess the statistical significance of the candidates thus identified. Controversy has surrounded the reliability of the false discovery rates estimates provided by the approximations used in early cancer genome studies. To address these, we develop a semiparametric Bayesian model that provides an accurate fit to the data. We use this model to generate a large collection of realistic scenarios, and evaluate alternative approaches on this collection. Our assessment is impartial in that the model used for generating data is not used by any of the approaches compared. And is objective, in that the scenarios are generated by a model that fits data. Our results quantify the conservative control of the false discovery rate with the Benjamini and Hockberg method compared to the empirical Bayes approach and the multiple testing method proposed in Storey [J. R. Stat. Soc. Ser. B Stat. Methodol. 64 (2002) 479–498]. Simulation results also show a negligible departure from the target false discovery rate for the methodology used in Sjoblom et al. [Science 314 (2006) 268–274].
Local Commuting Projector Hamiltonians and the Quantum Hall Effect

We prove that neither Integer nor Fractional Quantum Hall Effects with nonzero Hall conductivity are possible in gapped systems described by Local Commuting Projector Hamiltonians.
Vanadium Dioxide as a Natural Disordered Metamaterial: Perfect Thermal Emission and Large Broadband Negative Differential Thermal Emittance

thermal radiation and appears colder on an infrared camera. Our experimental approach allows for a direct measurement and extraction of wavelength- and temperature-dependent thermal emittance. We anticipate that emissivity engineering with thin-film geometries comprising VO2 and other thermochromic materials will find applications in infrared camouflage, thermal regulation, and infrared tagging and labeling.
Brane tilings and exceptional collections

Both brane tilings and exceptional collections are useful tools for describing the low energy gauge theory on a stack of D3-branes probing a Calabi-Yau singularity. We provide a dictionary that translates between these two heretofore unconnected languages. Given a brane tiling, we compute an exceptional collection of line bundles associated to the base of the non-compact Calabi-Yau threefold. Given an exceptional collection, we derive the periodic quiver of the gauge theory which is the graph theoretic dual of the brane tiling. Our results give new insight to the construction of quiver theories and their relation to geometry.
Finite-time blowup for a supercritical defocusing nonlinear wave system

We consider the global regularity problem for defocusing nonlinear wave systems $$ \Box u = (\nabla_{{\bf R}^m} F)(u) $$ on Minkowski spacetime ${\bf R}^{1+d}$ with d'Alambertian $\Box := -\partial_t^2 + \sum_{i=1}^d \partial_{x_i}^2$, the field $u: {\bf R}^{1+d} \to {\bf R}^m$ is vector-valued, and $F: {\bf R}^m \to {\bf R}$ is a smooth potential which is positive and homogeneous of order $p+1$ outside of the unit ball, for some $p >1$. This generalises the scalar defocusing nonlinear wave (NLW) equation, in which $m=1$ and $F(v) = \frac{1}{p+1} |v|^{p+1}$. It is well known that in the energy sub-critical and energy-critical cases when $d \leq 2$ or $d \geq 3$ and $p \leq 1+\frac{4}{d-2}$, one has global existence of smooth solutions (for dimensions $d \leq 7$ at least) from arbitrary smooth initial data $u(0), \partial_t u(0)$. In this paper we study the supercritical case where $d = 3$ and $p > 5$. We show that in this case, there exists smooth potential $F$ for some sufficiently large $m$ (in fact we can take $m=40$), positive and homogeneous of order $p+1$ outside of the unit ball, and a smooth choice of initial data $u(0), \partial_t u(0)$ for which the solution develops a finite time singularity. In fact the solution is discretely self-similar in a backwards light cone. The basic strategy is to first select the mass and energy densities of $u$, then $u$ itself, and then finally design the potential $F$ in order to solve the required equation. The Nash embedding theorem is used in the second step, explaining the need to take $m$ relatively large.
The k-core as a predictor of structural collapse in mutualistic ecosystems

Collapses of dynamical systems into irrecoverable states are observed in ecosystems, human societies, financial systems and network infrastructures. Despite their widespread occurrence and impact, these events remain largely unpredictable. In searching for the causes for collapse and instability, theoretical investigations have so far been unable to determine quantitatively the influence of the structural features of the network formed by the interacting species. Here, we derive the condition for the stability of a mutualistic ecosystem as a constraint on the strength of the dynamical interactions between species and a topological invariant of the network: the k-core. Our solution predicts that when species located at the maximum k-core of the network go extinct, as a consequence of sufficiently weak interaction strengths, the system will reach the tipping point of its collapse. As a key variable involved in collapse phenomena, monitoring the k-core of the network may prove a powerful method to anticipate catastrophic events in the vast context that stretches from ecological and biological networks to finance. Predicting the collapse of a dynamical system by monitoring the structure of its network of interaction takes the form of stability conditions formulated in terms of a topological invariant of the network, the k-core.
Quantum scrambling and the growth of mutual information

Quantum information scrambling refers to the loss of local recoverability of quantum information, which has found widespread attention from high energy physics to quantum computing. In the present analysis we propose a possible starting point for the development of a comprehensive framework for the thermodynamics of scrambling. To this end, we prove that the growth of entanglement as quantified by the mutual information is lower bounded by the time-dependent change of Out-Of-Time-Ordered Correlator. We further show that the rate of increase of the mutual information can be upper bounded by the sum of local entropy productions, and the exchange entropy arising from the flow of information between separate partitions of a quantum system. Our results are illustrated for the ion trap system, that was recently used to verify information scrambling in an experiment, and for the Sachdev-Ye-Kitaev model.
Perturbative quantum gravity comes of age

I argue that cosmological data from the epoch of primordial inflation is catalyzing the maturation of quantum gravity from speculation into a hard science. I explain why quantum gravitational effects from primordial inflation are observable. I then review what has been done, both theoretically and observationally, and what the future holds. I also discuss what this tells us about quantum gravity.
ON THE ORIGIN OF THE SALPETER SLOPE FOR THE INITIAL MASS FUNCTION

We suggest that the intrinsic, stellar initial mass function (IMF) follows a power-law slope {gamma} = 2, inherited from hierarchical fragmentation of molecular clouds into clumps and clumps into stars. The well-known, logarithmic Salpeter slope {Gamma} = 1.35 in clusters is then the aggregate slope for all the star-forming clumps contributing to an individual cluster, and it is steeper than the intrinsic slope within individual clumps because the smallest star-forming clumps contributing to any given cluster are unable to form the highest-mass stars. Our Monte Carlo simulations demonstrate that the Salpeter power-law index is the limiting value obtained for the cluster IMF when the lower-mass limits for allowed stellar masses and star-forming clumps are effectively equal, M{sub lo} = M{sub lo}. This condition indeed is imposed for the high-mass IMF tail by the turnover at the characteristic value m{sub c} {approx} 1 M{sub sun}. IMF slopes of {Gamma} {approx} 2 are obtained if the stellar and clump upper-mass limits are also equal M{sub up} = M{sub up} {approx} 100 M{sub sun}, and so our model explains the observed range of IMF slopes between {Gamma} {approx} 1 and 2. Flatter slopes of {Gamma} = 1 are expected when M{sub lo} >more » M{sub up}, which is a plausible condition in starbursts, where such slopes are suggested to occur. While this model is a simplistic parameterization of the star formation process, it seems likely to capture the essential elements that generate the Salpeter tail of the IMF for massive stars. These principles also likely explain the integrated galaxy IMF (IGIMF) effect seen in low-density star-forming environments.« less
Some new families of Tasoevian and Hurwitzian continued fractions

Here the fi(x) are polynomials with rational coecients taking only positive integral values for integral x 1, and at least one is non-constant. The integer n is termed the quasi-period of the continued fraction. The closed form for Hurwitzian continued fractions is not known in general. This class contains numbers like e = [2; 1; 2; 1; 1; 4; 1; 1; 6; 1;::: ] = [2; 1; 2m; 1 ] 1=1; tan 1 = [1; 1; 1; 3; 1; 5; 1; 7; 1; 9;::: ] = [1; 2m 1; 1 ] 1=1:
Finite-time Lyapunov exponents in the instantaneous limit and material transport

Lagrangian techniques, such as the finite-time Lyapunov exponent (FTLE) and hyperbolic Lagrangian coherent structures, have become popular tools for analyzing unsteady fluid flows. These techniques identify regions where particles transported by a flow will converge to and diverge from over a finite-time interval, even in a divergence-free flow. Lagrangian analyses, however, are time consuming and computationally expensive, hence unsuitable for quickly assessing short-term material transport. A recently developed method called Objective Eulerian Coherent Structures (OECSs) (Serra and Haller in Chaos Interdiscip J Nonlinear Sci 26(5):053110, 2016) rigorously connected Eulerian quantities to short-term Lagrangian transport. This Eulerian method is faster and less expensive to compute than its Lagrangian counterparts, and needs only a single snapshot of a velocity field. Along the same line, here we define the instantaneous Lyapunov Exponent, the instantaneous counterpart of the FTLE, and connect the Taylor series expansion of the right Cauchy-Green deformation tensor to the infinitesimal integration time limit of the FTLE. We illustrate our results on geophysical fluid flows from numerical models as well as analytical flows, and demonstrate the efficacy of attracting and repelling instantaneous Lyapunov exponent structures in predicting short-term material transport.
Virtual singular braids and links

Virtual singular braids are generalizations of singular braids and virtual braids. We define the virtual singular braid monoid via generators and relations, and prove Alexander- and Markov-type theorems for virtual singular links. We also show that the virtual singular braid monoid has another presentation with fewer generators.
Binary Frequencies in a Sample of Globular Clusters. I. Methodology and Initial Results

Binary stars are thought to be a controlling factor in globular cluster evolution, since they can heat the environmental stars by converting their binding energy to kinetic energy during dynamical interactions. Through such interaction, the binaries determine the time until core collapse. To test predictions of this model, we have determined binary fractions for 35 clusters. Here we present our methodology with a representative globular cluster NGC 4590. We use Hubble Space Telescope archival Advanced Camera for Surveys data in the F606W and F814W bands and apply point-spread-function-fitting photometry to obtain high quality color-magnitude diagrams. We formulate the star superposition effect as a Poisson probability distribution function, with parameters optimized through Monte Carlo simulations. A model-independent binary fraction of (6.2 ± 0.3)% is obtained by counting stars that extend to the red side of the residual color distribution after accounting for the photometric errors and the star superposition effect. A model-dependent binary fraction is obtained by constructing models with a known binary fraction and an assumed binary mass-ratio distribution function. This leads to a binary fraction range of 6.8%-10.8%, depending on the assumed shape to the binary mass-ratio distribution, with the best fit occurring for a binary distribution that favors low mass ratios (and higher binary fractions). We also represent the method for radial analysis of the binary fraction in the representative case of NGC 6981, which shows a decreasing trend for the binary fraction toward the outside, consistent with theoretical predictions for the dynamical effect on the binary fraction.
Smoothed weighted empirical likelihood ratio confidence intervals for quantiles

Thus far, likelihood-based interval estimates for quantiles have not been studied in the literature on interval censored case 2 data and partly interval censored data, and, in this context, the use of smoothing has not been considered for any type of censored data. This article constructs smoothed weighted empirical likelihood ratio confidence intervals (WELRCI) for quantiles in a unified framework for various types of censored data, including right censored data, doubly censored data, interval censored data and partly interval censored data. The fourth order expansion of the weighted empirical log-likelihood ratio is derived and the theoretical coverage accuracy equation for the proposed WELRCI is established, which generally guarantees at least ‘first order’ accuracy. In particular, for right censored data, we show that the coverage accuracy is at least O(n −1/2 ) and our simulation studies show that in comparison with empirical likelihood-based methods, the smoothing used in WELRCI generally provides a shorter confidence interval with comparable coverage accuracy. For interval censored data, it is interesting to find that with an adjusted rate n −1/3 , the weighted empirical log-likelihood ratio has an asymptotic distribution completely different from that obtained by the empirical likelihood approach and the resulting WELRCI perform favorably in the available comparison simulation studies.
Detection of a Water Tracer in Interstellar Comet 2I/Borisov

We present high spectral resolution optical spectra obtained with the ARCES instrument at Apache Point Observatory showing detection of the [O i] 6300 A line in interstellar comet 2I/Borisov. We employ the observed flux in this line to derive an H2O production rate of (6.3 ± 1.5) × 1026 mol s−1. Comparing to previously reported observations of CN, this implies a CN/H2O ratio of ~0.3%–0.6%. The lower end of this range is consistent with the average value in comets, while the upper end is higher than the average value for solar system comets, but still within the range of observed values. C2/H2O is depleted, with a value likely less than 0.1%. The dust-to-gas ratio is consistent with the normal value for solar system comets. Using a simple sublimation model we estimate an H2O active area of 1.7 km2, which for current estimates for the size of Borisov suggests active fractions between 1% and 150%, consistent with values measured in solar system comets. More detailed characterization of 2I/Borisov, including compositional information and properties of the nucleus, is needed to fully interpret the observed H2O production rate.
Driving quantum correlated atom-pairs from a Bose–Einstein condensate

The ability to cool quantum gases into the quantum degenerate realm has opened up possibilities for an extreme level of quantum-state control. In this paper, we investigate one such control protocol that demonstrates the resonant amplification of quasimomentum pairs from a Bose-Einstein condensate by the periodic modulation of the two-body s-wave scattering length. This shows a capability to selectively amplify quantum fluctuations with a predetermined momentum, where the momentum value can be spectroscopically tuned. A classical external field that excites pairs of particles with the same energy but opposite momenta is reminiscent of the coherently-driven nonlinearity in a parametric amplifier crystal in nonlinear optics. For this reason, it may be anticipated that the evolution will generate a squeezed matter-wave state in the quasiparticle mode on resonance with the modulation frequency. Our model and analysis is motivated by a recent experiment by Clark et al. that observed a time-of-flight pattern similar to an exploding firework. Since the drive is a highly coherent process, we interpret the observed firework patterns as arising from a monotonic growth in the two-body correlation amplitude, so that the jets should contain correlated atom pairs with nearly equal and opposite momenta. We propose a potential future experiment based on applying Ramsey interferometry to experimentally probe these pair correlations.
Foundations of a Multi-way Spectral Clustering Framework for Hybrid Linear Modeling

The problem of Hybrid Linear Modeling (HLM) is to model and segment data using a mixture of affine subspaces. Different strategies have been proposed to solve this problem, however, rigorous analysis justifying their performance is missing. This paper suggests the Theoretical Spectral Curvature Clustering (TSCC) algorithm for solving the HLM problem and provides careful analysis to justify it. The TSCC algorithm is practically a combination of Govindu’s multi-way spectral clustering framework (CVPR 2005) and Ng et al.’s spectral clustering algorithm (NIPS 2001). The main result of this paper states that if the given data is sampled from a mixture of distributions concentrated around affine subspaces, then with high sampling probability the TSCC algorithm segments well the different underlying clusters. The goodness of clustering depends on the within-cluster errors, the between-clusters interaction, and a tuning parameter applied by TSCC. The proof also provides new insights for the analysis of Ng et al. (NIPS 2001).
GROWTH PATTERN OF SILICON CLUSTERS

Tight-binding molecular dynamics simulated annealing technique is employed to search for the ground state geometries of silicon clusters containing 11–17 atoms. These studies revealed that layer formation is the dominant growth pattern in all these clusters. Fullerene-like precursor structures consisting of fused pentagon rings are also observed. The atoms in all these clusters exhibit pronounced preference for residing on the surface.
The RRAT Trap: Interferometric Localization of Radio Pulses from J0628+0909

We present the first blind interferometric detection and imaging of a millisecond radio transient with an observation of transient pulsar J0628+0909. We developed a special observing mode of the Karl G. Jansky Very Large Array to produce correlated data products (i.e., visibilities and images) on a timescale of 10 ms. Correlated data effectively produce thousands of beams on the sky that can localize sources anywhere over a wide field of view. We used this new observing mode to find and image pulses from the rotating radio transient (RRAT) J0628+0909, improving its localization by two orders of magnitude. Since the location of the RRAT was only approximately known when first observed, we searched for transients using a wide-field detection algorithm based on the bispectrum, an interferometric closure quantity. Over 16 minutes of observing, this algorithm detected one transient offset roughly 1' from its nominal location; this allowed us to image the RRAT to localize it with an accuracy of 1.''6. With a priori knowledge of the RRAT location, a traditional beam-forming search of the same data found two lower significance pulses. The refined RRAT position excludes all potential multiwavelength counterparts, limiting its optical luminosity to L{sub i{sup '}}<1.1 Multiplication-Sign 10{sup 31}more » erg s{sup -1} and disfavoring source models with luminous neutron stars.« less
A SEARCH FOR EXOZODIACAL CLOUDS WITH KEPLER

Planets embedded within dust disks may drive the formation of large scale clumpy dust structures by trapping dust into resonant orbits. Detection and subsequent modeling of the dust structures would help constrain the mass and orbit of the planet and the disk architecture, give clues to the history of the planetary system, and provide a statistical estimate of disk asymmetry for future exoEarth-imaging missions. Here, we present the first search for these resonant structures in the inner regions of planetary systems by analyzing the light curves of hot Jupiter planetary candidates identified by the Kepler mission. We detect only one candidate disk structure associated with KOI 838.01 at the 3{sigma} confidence level, but subsequent radial velocity measurements reveal that KOI 838.01 is a grazing eclipsing binary and the candidate disk structure is a false positive. Using our null result, we place an upper limit on the frequency of dense exozodi structures created by hot Jupiters. We find that at the 90% confidence level, less than 21% of Kepler hot Jupiters create resonant dust clumps that lead and trail the planet by {approx}90 Degree-Sign with optical depths {approx}> 5 Multiplication-Sign 10{sup -6}, which corresponds to the resonant structure expected for amore » lone hot Jupiter perturbing a dynamically cold dust disk 50 times as dense as the zodiacal cloud.« less
Cabling sequences of tunnels of torus knots

In previous work [4], we developed a theory of tunnels of tunnel number 1 knots in S3 . It shows that every tunnel can be obtained from the unique tunnel of the trivial knot by a uniquely determined sequence of “cabling constructions”. A cabling construction is determined by a rational parameter, called its “slope,” so this leads to a parameterization of all tunnels of all tunnel number 1 knots by sequences of rational numbers and “binary” invariants. Various applications of the theory are given in [4], [5] and [6], as well as other work in preparation.
YANG–MILLS GRAVITY IN FLAT SPACE–TIME I: CLASSICAL GRAVITY WITH TRANSLATION GAUGE SYMMETRY

We formulate and explore the physical implications of a new translation gauge theory of gravity in flat space–time with a new Yang–Mills action, which involves quadratic gauge curvature and fermions. The theory shows that the presence of an "effective Riemann metric tensor" for the motions of classical particles and light rays is probably the manifestation of the translation gauge symmetry in flat physical space–time. In the post-Newtonian approximation of the tensor gauge field produced by the energy–momentum tensor, the results are shown to be consistent with classical tests of gravity and with the quadrupole radiations of binary pulsars.
Electron Correlation and Spin Dynamics in Iron Pnictides and Chalcogenides

Superconductivity in the iron pnictides and chalcogenides is closely connected to a bad-metal normal state and a nearby antiferromagnetic order. Therefore, considerable attention has been focused on the role of electron correlations and spin dynamics. In this article, we summarize some key experiments that quite directly imply strong electron correlations in these materials, and discuss aspects of the recent theoretical studies on these issues. In particular, we outline a w-expansion, which treats the correlation effects using the Mott transition as the reference point. For the parent systems, it gives rise to an effective J1-J2 model that is coupled to the itinerant electrons in the vicinity of the Fermi energy; this model yields an isoelectronically-tuned quantum critical point, and allows a study of the distribution of the spin spectral weight in the energy and momentum space in the paramagnetic phase. Within the same framework, we demonstrate the Mott insulating phase in the iron oxychalcogenides as well as the alkaline iron selenides; for the latter system, we also consider the role of an orbital-selective Mott phase. Finally, we discuss the singlet superconducting pairing driven by the short-range J1-J2 interactions. Our considerations highlight the iron pnictides and chalcogenides as exemplifying strongly-correlated electron systems at the boundary of electronic localization and itinerancy.
Lower bounds for the energy in a crumpled elastic sheet: a minimal ridge

We study the linearized Foppl–von Karman theory of a long, thin rectangular elastic membrane that is bent through an angle 2 α. We prove rigorous bounds for the minimum energy of this configuration in terms of the plate thickness, σ, and the bending angle. We show that the minimum energy scales as σ5/3 α7/3. This scaling is in sharp contrast with previously obtained results for the linearized theory of thin sheets with isotropic compression boundary conditions, where the energy scales as σ.
EDGE IDEALS OF WEIGHTED GRAPHS

We study weighted graphs and their "edge ideals" which are ideals in polynomial rings that are defined in terms of the graphs. We provide combinatorial descriptions of m-irreducible decompositions for the edge ideal of a weighted graph in terms of the combinatorics of "weighted vertex covers". We use these, for instance, to say when these ideals are m-unmixed. We explicitly describe which weighted cycles, suspensions, and trees are unmixed and which ones are Cohen–Macaulay, and we prove that all weighted complete graphs are Cohen–Macaulay.
TASI 2011 Lectures Notes:. Two-Component Fermion Notation and Supersymmetry

These notes, based on work with Herbi Dreiner and Howie Haber, discuss how to do practical calculations of cross sections and decay rates using two-component fermion notation, as appropriate for supersymmetry and other beyond-the-Standard-Model theories. Included are a list of two-component fermion Feynman rules for the Minimal Supersymmetric Standard Model, and some example calculations.
Minimalist approach to the classification of symmetry protected topological phases

A number of proposals with differing predictions (e.g. Borel group cohomology, oriented cobordism, group supercohomology, spin cobordism, etc.) have been made for the classification of symmetry protected topological (SPT) phases. Here we treat various proposals on an equal footing and present rigorous, general results that are independent of which proposal is correct. We do so by formulating a minimalist Generalized Cohomology Hypothesis, which is satisfied by existing proposals and captures essential aspects of SPT classification. From this Hypothesis alone, formulas relating classifications in different dimensions and/or protected by different symmetry groups are derived. Our formalism is expected to work for fermionic as well as bosonic phases, Floquet as well as stationary phases, and spatial as well as on-site symmetries. As an application, we predict that the complete classification of 3-dimensional bosonic SPT phases with space group symmetry $G$ is $H^4_{\rm Borel}\left(G;U(1)\right) \oplus H^1_{\rm group}\left(G;\mathbb Z\right)$, where the $H^1$ term classifies phases beyond the Borel group cohomology proposal.
Percolation of disordered jammed sphere packings

We determine the site and bond percolation thresholds for a system of disordered jammed sphere packings in the maximally random jammed state, generated by the Torquato-Jiao algorithm. For the site threshold, which gives the fraction of conducting vs. non-conducting spheres necessary for percolation, we find $p_c = 0.3116(3)$, consistent with the 1979 value of Powell $0.310(5)$ and identical within errors to the threshold for the simple-cubic lattice, 0.311608, which shares the same average coordination number of 6. In terms of the volume fraction $\varphi$, the threshold corresponds to a critical value $\varphi_c = 0.199$. For the bond threshold, which apparently was not measured before, we find $p_c = 0.2424(3)$. To find these thresholds, we considered two shape-dependent universal ratios involving the size of the largest cluster, fluctuations in that size, and the second moment of the size distribution; we confirmed the ratios' universality by also studying the simple-cubic lattice with a similar cubic boundary. The results are applicable to many problems including conductivity in random mixtures, glass formation, and drug loading in pharmaceutical tablets.
Determining X-Ray Source Intensity and Confidence Bounds in Crowded Fields

We present a rigorous description of the general problem of aperture photometry in high-energy astrophysics photon-count images, in which the statistical noise model is Poisson, not Gaussian. We compute the full posterior probability density function for the expected source intensity for various cases of interest, including the important cases in which both source and background apertures contain contributions from the source, and when multiple source apertures partially overlap. A Bayesian approach offers the advantages of allowing one to (1) include explicit prior information on source intensities, (2) propagate posterior distributions as priors for future observations, and (3) use Poisson likelihoods, making the treatment valid in the low-counts regime. Elements of this approach have been implemented in the Chandra Source Catalog.
Posterior Re-calibration for Imbalanced Datasets

Neural Networks can perform poorly when the training label distribution is heavily imbalanced, as well as when the testing data differs from the training distribution. In order to deal with shift in the testing label distribution, which imbalance causes, we motivate the problem from the perspective of an optimal Bayes classifier and derive a post-training prior rebalancing technique that can be solved through a KL-divergence based optimization. This method allows a flexible post-training hyper-parameter to be efficiently tuned on a validation set and effectively modify the classifier margin to deal with this imbalance. We further combine this method with existing likelihood shift methods, re-interpreting them from the same Bayesian perspective, and demonstrating that our method can deal with both problems in a unified way. The resulting algorithm can be conveniently used on probabilistic classification problems agnostic to underlying architectures. Our results on six different datasets and five different architectures show state of art accuracy, including on large-scale imbalanced datasets such as iNaturalist for classification and Synthia for semantic segmentation. Please see this https URL for implementation.