cssi/SciSciGPT-SciSciNet huggingface dataset:
scFTD-seq: freeze-thaw lysis based, portable approach toward highly distributed single-cell 3' mRNA profiling

Cellular barcoding of 3' mRNAs enabled massively parallel profiling of single-cell gene expression and has been implemented in droplet and microwell based platforms. The latter further adds the value for compatibility with low input samples, optical imaging, scalability, and portability. However, cell lysis in microwells remains challenging despite the recently developed sophisticated solutions. Here, we present scFTD-seq, a microchip platform for performing single-cell freeze-thaw lysis directly toward 3' mRNA sequencing. It offers format flexibility with a simplified, widely adoptable workflow that reduces the number of preparation steps and hands-on time, with the quality of data and cost per sample matching that of the state-of-the-art scRNA-seq platforms. Freeze-thaw, known as an unfavorable lysis method resulting in possible RNA fragmentation, turns out to be fully compatible with 3' scRNA-seq. We applied it to the profiling of circulating follicular helper T cells implicated in systemic lupus erythematosus pathogenesis. Our results delineate the heterogeneity in the transcriptional programs and effector functions of these rare pathogenic T cells. As scFTD-seq decouples on-chip cell isolation and library preparation, we envision it to allow sampling at the distributed sites including point-of-care settings and downstream processing at centralized facilities, which should enable wide-spread adoption beyond academic laboratories.
Effect of cellular de-differentiation on the dynamics and evolution of tissue and tumor cells in mathematical models with feedback regulation

Abstract Tissues are maintained by adult stem cells that self-renew and also differentiate into functioning tissue cells. Homeostasis is achieved by a set of complex mechanisms that involve regulatory feedback loops. Similarly, tumors are believed to be maintained by a minority population of cancer stem cells, while the bulk of the tumor is made up of more differentiated cells, and there is indication that some of the feedback loops that operate in tissues continue to be functional in tumors. Mathematical models of such tissue hierarchies, including feedback loops, have been analyzed in a variety of different contexts. Apart from stem cells giving rise to differentiated cells, it has also been observed that more differentiated cells can de-differentiate into stem cells, both in healthy tissue and tumors, aspects of which have also been investigated mathematically. This paper analyses the effect of de-differentiation on the basic and evolutionary dynamics of cells in the context of tissue hierarchy models that include negative feedback regulation of the cell populations. The models predict that in the presence of de-differentiation, the fixation probability of a neutral mutant is lower than in its absence. Therefore, if de-differentiation occurs, a mutant with identical parameters compared to the wild-type cell population behaves like a disadvantageous mutant. Similarly, the process of de-differentiation is found to lower the fixation probability of an advantageous mutant. These results indicate that the presence of de-differentiation can lower the rates of tumor initiation and progression in the context of the models considered here.
Vibrational Properties of Monophosphate Tungsten Bronzes (PO2)4(WO3)2m (m = 4, 6)

We report the vibrational properties of quasi-two-dimensional charge density wave (CDW) materials (PO2)4(WO3)2m (m = 4, 6). The CDW transitions occur at 80 and 54 K for m = 4 and 120 and 60 K for m...
Contextual Affective Analysis: A Case Study of People Portrayals in Online #MeToo Stories

In October 2017, numerous women accused producer Harvey Weinstein of sexual harassment. Their stories encouraged other women to voice allegations of sexual harassment against many high profile men, including politicians, actors, and producers. These events are broadly referred to as the #MeToo movement, named for the use of the hashtag “#metoo” on social media platforms like Twitter and Facebook. The movement has widely been referred to as “empowering” because it has amplified the voices of previously unheard women over those of traditionally powerful men. In this work, we investigate dynamics of sentiment, power and agency in online media coverage of these events. Using a corpus of online media articles about the #MeToo movement, we present a contextual affective analysis—an entity-centric approach that uses contextualized lexicons to examine how people are portrayed in media articles. We show that while these articles are sympathetic towards women who have experienced sexual harassment, they consistently present men as most powerful, even after sexual assault allegations. While we focus on media coverage of the #MeToo movement, our method for contextual affective analysis readily generalizes to other domains.1
Oxidative Stress in Response to Saturated Fat Ingestion Is Linked to Insulin Resistance and Hyperandrogenism in Polycystic Ovary Syndrome.

Context Oxidative stress and insulin resistance are often present in polycystic ovary syndrome (PCOS). Objective We determined the effect of saturated fat ingestion on leukocytic reactive oxygen species (ROS) generation, p47phox expression, and circulating thiobarbituric acid-reactive substances (TBARS) in women with PCOS. Design Cross-sectional study. Setting Academic medical center. Patients Twenty women of reproductive age with PCOS (10 lean, 10 with obesity) and 19 ovulatory control subjects (10 lean, 9 with obesity). Main outcome measures ROS generation and p47phox mRNA and protein content were quantified in leukocytes, and TBARS was measured in plasma from blood drawn while the subjects were fasting and 2, 3, and 5 hours after saturated fat ingestion. Insulin sensitivity was derived from an oral glucose tolerance test (ISOGTT). Androgen secretion was assessed from blood drawn while the subjects were fasting and 24, 48, and 72 hours after human chorionic gonadotropin (HCG) administration. Results Regardless of weight class, women with PCOS exhibited lipid-induced increases in leukocytic ROS generation and p47phox mRNA and protein content as well as plasma TBARS compared with lean control subjects. Both PCOS groups exhibited lower ISOGTT and greater HCG-stimulated androgen secretion compared with control subjects. The ROS generation, p47phox, and TBARS responses were negatively correlated with ISOGTT and positively correlated with HCG-stimulated androgen secretion. Conclusion In PCOS, increases in ROS generation, p47phox gene expression, and circulating TBARS in response to saturated fat ingestion are independent of obesity. Circulating mononuclear cells and excess adipose tissue are separate and distinct contributors to oxidative stress in this disorder.
On metric properties of maps between Hamming spaces and related graph homomorphisms

A mapping of k-bit strings into n-bit strings is called an ( α , β ) -map if k-bit strings which are more than αk apart are mapped to n-bit strings that are more than βn apart in Hamming distance. This is a relaxation of the classical problem of constructing error-correcting codes, which corresponds to α = 0 . Existence of an ( α , β ) -map is equivalent to existence of a graph homomorphism H ź ( k , α k ) ź H ź ( n , β n ) , where H ( n , d ) is a Hamming graph with vertex set { 0 , 1 } n and edges connecting vertices differing in d or fewer entries.This paper proves impossibility results on achievable parameters ( α , β ) in the regime of n , k ź ∞ with a fixed ratio n k = ź . This is done by developing a general criterion for existence of graph-homomorphism based on the semi-definite relaxation of the independence number of a graph (known as the Schrijver's ź-function). The criterion is then evaluated using some known and some new results from coding theory concerning the ź-function of Hamming graphs. As an example, it is shown that if β 1 / 2 and n k - integer, the n k -fold repetition map achieving α = β is asymptotically optimal.Finally, constraints on configurations of points and hyperplanes in projective spaces over F 2 are derived.
An Empirical Study on the Names of Points of Interest and Their Changes with Geographic Distance.

While Points Of Interest (POIs), such as restaurants, hotels, and barber shops, are part of urban areas irrespective of their specific locations, the names of these POIs often reveal valuable information related to local culture, landmarks, influential families, figures, events, and so on. Place names have long been studied by geographers, e.g., to understand their origins and relations to family names. However, there is a lack of large-scale empirical studies that examine the localness of place names and their changes with geographic distance. In addition to enhancing our understanding of the coherence of geographic regions, such empirical studies are also significant for geographic information retrieval where they can inform computational models and improve the accuracy of place name disambiguation. In this work, we conduct an empirical study based on 112,071 POIs in seven US metropolitan areas extracted from an open Yelp dataset. We propose to adopt term frequency and inverse document frequency in geographic contexts to identify local terms used in POI names and to analyze their usages across different POI types. Our results show an uneven usage of local terms across POI types, which is highly consistent among different geographic regions. We also examine the decaying effect of POI name similarity with the increase of distance among POIs. While our analysis focuses on urban POI names, the presented methods can be generalized to other place types as well, such as mountain peaks and streets.
Convergence of Local Statistics of Dyson Brownian Motion

We analyze the rate of convergence of the local statistics of Dyson Brownian motion to the GOE/GUE for short times t = o(1) with deterministic initial data V. Our main result states that if the density of states of V is bounded both above and away from 0 down to scales $${\ell \ll t}$$ in a small interval of size $${G \gg t}$$ around an energy $${E_0}$$ , then the local statistics coincide with the GOE/GUE near the energy $${E_0}$$ after time t. Our methods are partly based on the idea of coupling two Dyson Brownian motions from Bourgade et al. (Commun Pure Appl Math, 2016), the parabolic regularity result of Erdős and Yau (J Eur Math Soc 17(8):1927–2036, 2015), and the eigenvalue rigidity results of Lee and Schnelli (J Math Phys 54(10):103504, 2013).
Learning Influence-Receptivity Network Structure with Guarantee

Traditional works on community detection from observations of information cascade assume that a single adjacency matrix parametrizes all the observed cascades. However, in reality the connection structure usually does not stay the same across cascades. For example, different people have different topics of interest, therefore the connection structure depends on the information/topic content of the cascade. In this paper we consider the case where we observe a sequence of noisy adjacency matrices triggered by information/events with different topic distributions. We propose a novel latent model using the intuition that a connection is more likely to exist between two nodes if they are interested in similar topics, which are common with the information/event. Specifically, we endow each node with two node-topic vectors: an influence vector that measures how influential/authoritative they are on each topic; and a receptivity vector that measures how receptive/susceptible they are to each topic. We show how these two node-topic structures can be estimated from observed adjacency matrices with theoretical guarantee on estimation error, in cases where the topic distributions of the information/events are known, as well as when they are unknown. Experiments on synthetic and real data demonstrate the effectiveness of our model and superior performance compared to state-of-the-art methods.
Deep reinforcement learning for tensegrity robot locomotion

Tensegrity robots, composed of rigid rods connected by elastic cables, have a number of unique properties that make them appealing for use as planetary exploration rovers. However, control of tensegrity robots remains a difficult problem due to their unusual structures and complex dynamics. In this work, we show how locomotion gaits can be learned automatically using a novel extension of mirror descent guided policy search (MDGPS) applied to periodic locomotion movements, and we demonstrate the effectiveness of our approach on tensegrity robot locomotion. We evaluate our method with real-world and simulated experiments on the SUPERball tensegrity robot, showing that the learned policies generalize to changes in system parameters, unreliable sensor measurements, and variation in environmental conditions, including varied terrains and a range of different gravities. Our experiments demonstrate that our method not only learns fast, power-efficient feedback policies for rolling gaits, but that these policies can succeed with only the limited onboard sensing provided by SUPERball's accelerometers. We compare the learned feedback policies to learned open-loop policies and hand-engineered controllers, and demonstrate that the learned policy enables the first continuous, reliable locomotion gait for the real SUPERball robot. Our code and supplementary material is available from http://rll.berkeley.edu/drl_tensegrity.
GERBES, HOLONOMY FORMS AND REAL STRUCTURES

We study geometry on real gerbes in the spirit of the Cheeger–Simons theory. The concepts of adaptations and holonomy forms are introduced for flat connections on real gerbes. Their relations to complex gerbes with connections are presented, as well as results in loop and map spaces.
Improved bounds on the number of numerical semigroups of a given genus

We improve the previously best known lower and upper bounds on the number ng of numerical semigroups of genus g. Starting from a known recursive description of the tree T of numerical semigroups, we analyze some of its properties and use them to construct approximations of T by generating trees whose nodes are labeled by certain parameters of the semigroups. We then translate the succession rules of these trees into functional equations for the generating functions that enumerate their nodes, and solve these equations to obtain the bounds. Some of our bounds involve the Fibonacci numbers, and the others are expressed as generating functions. We also give upper bounds on the number of numerical semigroups having an infinite number of descendants in T.
P-capacity vs surface-area ☆

Abstract This paper discovers two relationships between the [ 1 , n ) ∋ p -capacity and the surface-area via the Lebesgue volume and the Willmore energy in R n respectively, whence showing: if Ω ⊂ R n is a convex, compact, smooth set with its interior Ω ∘ ≠ ∅ and the mean curvature H ( ∂ Ω , ⋅ ) > 0 of its boundary ∂Ω then ( n ( p − 1 ) p ( n − 1 ) ) p − 1 ≤ ( cap p ( Ω ) ( p − 1 n − p ) 1 − p σ n − 1 ) ( area ( ∂ Ω ) σ n − 1 ) n − p n − 1 ≤ ( ∫ ∂ Ω ( H ( ∂ Ω , ⋅ ) ) n − 1 d σ ( ⋅ ) σ n − 1 ) p − 1 n − 1 and hence c a p 1 ( Ω ) area ( ∂ Ω ) = 1 ≤ ∫ ∂ Ω ( H ( ∂ Ω , ⋅ ) ) n − 1 d σ ( ⋅ ) σ n − 1 . Of particular interest is that if p = 2 3 = n in the last but one inequality then cap 2 ( Ω ) ≥ 2 − 1 3 π area ( ∂ Ω ) where 2 − 1 3 π is smaller than 2 2 2 / π (conjectured by Polya–Szego in [25, (2)] ) while bigger than 2 2 / π (obtained by Polya–Szego in [27, p. 165(4)] ).
Rigorous derivation of the Landau equation in the weak coupling limit

We examine a family of microscopic models of plasmas, with a parameter $\alpha$ comparing the typical distance between collisions to the strength of the grazing collisions. These microscopic models converge in distribution, in the weak coupling limit, to a velocity diffusion described by the linear Landau equation (also known as the Fokker-Planck equation). The present work extends and unifies previous results that handled the extremes of the parameter $\alpha$ to the whole range $(0, 1/2]$, by showing that clusters of overlapping obstacles are negligible in the limit. Additionally, we study the diffusion coefficient of the Landau equation and show it to be independent of the parameter.
Extremal rays in the Hermitian eigenvalue problem

The Hermitian eigenvalue problem asks for the possible eigenvalues of a sum of $$n\times n$$ Hermitian matrices, given the eigenvalues of the summands. The regular faces of the cones $$\Gamma _n(s)$$ controlling this problem have been characterized in terms of classical Schubert calculus by the work of several authors. We determine extremal rays of $$\Gamma _n(s)$$ (which are never regular faces) by relating them to the geometry of flag varieties: the extremal rays either arise from “modular intersection loci”, or by “induction” from extremal rays of smaller groups. Explicit formulas are given for both the extremal rays coming from such intersection loci, and for the induction maps.
A tame Cantor set

A Cantor set is a non-empty, compact set that has neither interior nor isolated points. In this paper a Cantor set $K\subseteq \mathbb{R}$ is constructed such that every set definable in $(\mathbb{R},<,+,\cdot,K)$ is Borel. In addition, we prove quantifier-elimination and completeness results for $(\mathbb{R},<,+,\cdot,K)$, making the set $K$ the first example of a modeltheoretically tame Cantor set. This answers questions raised by Friedman, Kurdyka, Miller and Speissegger. The work in this paper depends crucially on results about automata on infinite words, in particular B\"uchi's celebrated theorem on the monadic second-order theory of one successor and McNaughton's theorem on Muller automata, which had never been used in the setting of expansions of the real field.
Pattern Formation in Rayleigh Benard Convection

The main objective of this article is to study the three-dimensional Rayleigh-Benard convection in a rectangular domain from a pattern formation perspective. It is well known that as the Rayleigh number crosses a critical threshold, the system undergoes a Type-I transition, characterized by an attractor bifurcation. The bifurcated attractor is an (m-1)-dimensional homological sphere where m is the multiplicity of the first critical eigenvalue. When m=1, the structure of this attractor is trivial. When m=2, it is known that the bifurcated attractor consists of steady states and their connecting heteroclinic orbits. The main focus of this article is then on the pattern selection mechanism and stability of rolls, rectangles and mixed modes (including hexagons) for the case where m=2. We derive in particular a complete classification of all transition scenarios, determining the patterns of the bifurcated steady states, their stabilities and the basin of attraction of the stable ones. The theoretical results lead to interesting physical conclusions, which are in agreement with known experimental results. For example, it is shown in this article that only the pure modes are stable whereas the mixed modes are unstable.
Control Distance and Energy Scaling of Complex Networks

It has recently been shown that the average energy required to control a subset of target nodes in a complex network scales exponentially with the cardinality of the subset. While the mean scales exponentially, the variance of the control energy over different subsets of target nodes can be large and has, as of yet, not been explained. Here, we provide an explanation of the large variance as a result of both the length of the path that connects control inputs to the target nodes and the redundancy of paths of shortest length. Our first result provides an upper bound of the control energy as a function of path length between driver node and target node along an infinite path graph for a single target node. We also show that the energy estimate is still very accurate even when finite size effects are taken into account. Our second result refines the upper bound, by an order of magnitude or more, taking into account not only the length of the path, but also the redundancy of paths. Finally, we lay out the foundations for a more accurate estimation of the control energy for the multi-target node and multi-driver node problem.
Mean Field Equilibria for Resource Competition in Spatial Settings

We study a model of competition among nomadic agents for time-varying and location-specific resources arising in crowdsourced transportation services, online communities, and traditional location-b...
Numeric Invariants from Multidimensional Persistence

Topological data analysis is the study of data using techniques from algebraic topology. Often, one begins with a finite set of points representing data and a “filter” function which assigns a real number to each datum. Using both the data and the filter function, one can construct a filtered complex for further analysis. For example, applying the homology functor to the filtered complex produces an algebraic object known as a “one-dimensional persistence module”, which can often be interpreted as a finite set of intervals representing various geometric features in the data. If one runs the above process incorporating multiple filter functions simultaneously, one instead obtains a multidimensional persistence module. Unfortunately, these are much more difficult to interpret. In this article, we analyze the space of multidimensional persistence modules from the perspective of algebraic geometry. We first build a moduli space of a certain subclass of easily analyzed multidimensional persistence modules, which we construct specifically to capture much of the information which can be gained by using multidimensional persistence instead of one-dimensional persistence. We argue that the global sections of this space provide interesting numeric invariants when evaluated against our subclass of multidimensional persistence modules. Finally, we extend these global sections to the space of all multidimensional persistence modules and discuss how the resulting numeric invariants might be used to study data. This paper extends the results of Adcock et al. (Homol Homotopy Appl 18(1), 381–402, 2016) by constructing numeric invariants from the computation of a multidimensional persistence module as given by Carlsson et al. (J Comput Geom 1(1), 72–100, 2010).
Upper bounds for s-distance sets and equiangular lines

Abstract The set of points in a metric space is called an s-distance set if pairwise distances between these points admit only s distinct values. Two-distance spherical sets with the set of scalar products { α , − α } , α ∈ [ 0 , 1 ) , are called equiangular. The problem of determining the maximum size of s-distance sets in various spaces has a long history in mathematics. We suggest a new method of bounding the size of an s-distance set in compact two-point homogeneous spaces via zonal spherical functions. This method allows us to prove that the maximum size of a spherical two-distance set in R n , n ≥ 7 , is n ( n + 1 ) 2 with possible exceptions for some n = ( 2 k + 1 ) 2 − 3 , k ∈ N . We also prove the universal upper bound ∼ 2 3 n a 2 for equiangular sets with α = 1 a and, employing this bound, prove a new upper bound on the size of equiangular sets in all dimensions. Finally, we classify all equiangular sets reaching this new bound.
Time-Series Based Thermography on Concrete Block Void Detection

Using thermography as a nondestructive method for subsurface detection of the concrete structure has been developed for decades. However, the performance of current practice is limited due to the heavy reliance on the environmental conditions as well as complex environmental noises. A non-time-series method suffers from the issue of solar radiation reflected by the target during heating stage, and issues of potential non-uniform heat distribution. These limitations are the major constraints of the traditional single thermal image method. Time series-based methods such as Fourier transform-based pulse phase thermography, principle component thermography, and high order statistics have been reported with robust results on surface reflective property difference and non-uniform heat distribution under the experimental setting. This paper aims to compare the performance of above methods to that of the conventional static thermal imaging method. The case used for the comparison is to detect voids in a hollow concrete block during the heating phase. The result was quantitatively evaluated by using Signal-to-Noise Ratio. Favorable performance was observed using time-series methods compared to the single image approach.
On the Quantitative Hardness of CVP

For odd integers p &#x2265; 1 (and p = &#x221E;), we show that the Closest Vector Problem in the &#x2113;p norm (CVP_p) over rank n lattices cannot be solved in 2^(1-&#x2265;) n time for any constant &#x2265; 0 unless the Strong Exponential Time Hypothesis (SETH) fails. We then extend this result to almost all values of p &#x2265; 1, not including the even integers. This comes tantalizingly close to settling the quantitative time complexity of the important special case of CVP_2 (i.e., CVP in the Euclidean norm), for which a 2^{n +o(n)}-time algorithm is known. In particular, our result applies for any p = p(n) &#x2260; 2 that approaches 2 as n &#x21A6; &#x221E;.We also show a similar SETH-hardness result for SVP_&#x221E;; hardness of approximating CVP_p to within some constant factor under the so-called Gap-ETH assumption; and other hardness results for CVP_p and CVPP_p for any 1 &#x2264; p
A SHARP INEQUALITY AND ITS APPLICATIONS

We establish the analog Bliss and Hardy inequalities with sharp constant involving exponential weight function. One special case of the inequalities (for n = 2) leads to a direct proof of Onofri inequality on S2.
Fast Desktop-Scale Extrusion Additive Manufacturing

Abstract Significant improvements to the throughput of additive manufacturing (AM) processes are essential to their cost-effectiveness and competitiveness with traditional processing routes. Moreover, high-throughput AM processes, in combination with the geometric versatility of AM, will enable entirely new workflows for product design and customization. We present the design and validation of a desktop-scale extrusion AM system that achieves a much greater build rate than benchmarked commercial systems. This system, which we call ‘FastFFF’, is motivated by our recent analysis of the rate-limiting mechanisms to conventional fused filament fabrication (FFF) technology. The FastFFF system mutually overcomes these limits, using a nut-feed extruder, laser-heated polymer liquefier, and servo-driven parallel gantry system to achieve high extrusion force, rapid filament heating, and fast gantry motion, respectively. The extrusion and heating mechanisms are contained in a compact printhead that receives a threaded filament and augments conduction heat transfer with a fiber-coupled diode laser. The prototype system achieves a volumetric build rate of 127 cm3/hr, which is approximately 7-fold greater than commercial desktop FFF systems, at comparable resolution; the maximum extrusion rate of the printhead is ∼14-fold greater (282 cm3/hr) than our benchmarks. The performance limits of the printhead and motion systems are characterized, and the tradeoffs between build rate and resolution are assessed and discussed. High-speed desktop AM raises the possibility of new use cases and business models for AM, where handheld parts are built in minutes rather than hours. Adaptation of this technology to print high-temperature thermoplastics and composite materials, which require high extrusion forces, is also of interest.
Multirobot cliff climbing on low-gravity environments

Exploration of extreme environments, including caves, canyons and cliffs on low-gravity surfaces such as the Moon, Mars and asteroids can provide insight into the geological history of the solar system, origins of water, life and prospect for future habitation and resource exploitation. Current methods of exploration utilize large rovers that are unsuitable for exploring these extreme environments. In this work, we analyze the feasibility of small, low-cost, reconfigurable multirobot systems to climb steep cliffs and canyon walls. Each robot is a 30-cm sphere covered in microspines for gripping onto rugged surfaces and attaches to several robots using a spring-tether. Even if one robot were to slip and fall, the system would be held up with multiple attachment points much like a professional alpine climber. We analyzed and performed detailed simulations of the design configuration space to identify an optimal system design that trades-off climbing performance with risk of falling. Our results show that with increased number of robots, climbs can be performed faster (through parallelism) and with less risk of falling. The results show a pathway towards demonstration of the system on real robots.
Euler Characteristics on virtually free products

We define Euler characteristics on classes of residually finite and virtually torsion free groups and we show that they satisfy certain formulas in the case of amalgamated free products and HNN ext...
Modeling coating flow and surfactant dynamics inside the alveolar compartment

We derive a new model for the coating flow inside the alveolar compartment, taking into account pulmonary surfactant production and recycling by Type 2 cells as well as its degradation. As the thickness of alveolar coating is much smaller than the average radius of the alveoli, we employ the classical lubrication approximation to describe the thin liquid film dynamics in the presence of pulmonary surfactant, which is a surface tension-reducing agent and thus prevents the lungs from collapse. In the lubrication limit, we derive a degenerate system of two coupled parabolic partial differential equations that describe the time evolution of the thickness of the coating film inside the alveoli together with that of the surfactant concentration at the interface. We present numerical simulations using parameter values consistent with experimental measurements. With Marangoni effects being significant, it is found that any initial non-uniformity in surfactant concentration leads to a very fast redistribution of surfactant and accompanying change in film thickness, followed by a much slower relaxation of the film thickness to equilibrium during which surfactant concentration remains relatively uniform.
A testing based approach to the discovery of differentially correlated variable sets

Given data obtained under two sampling conditions, it is often of interest to identify variables that behave differently in one condition than in the other. We introduce a method for differential analysis of second-order behavior called Differential Correlation Mining (DCM). The DCM method identifies differentially correlated sets of variables, with the property that the average pairwise correlation between variables in a set is higher under one sample condition than the other. DCM is based on an iterative search procedure that adaptively updates the size and elements of a candidate variable set. Updates are performed via hypothesis testing of individual variables, based on the asymptotic distribution of their average differential correlation. We investigate the performance of DCM by applying it to simulated data as well as to recent experimental datasets in genomics and brain imaging.
Current status of dynamical modeling of fluctuations at the QCD phase transition in heavy-ion collisions

For a complete understanding of the QCD phase diagram it is important to connect first-principle thermodynamic calculations to experimental data from the RHIC Beam Energy Scan and the future experimental facilities FAIR, GSI, and NICA, Dubna. This can only be achieved by a realistic modeling of the dynamical evolution of critical fluctuations in heavy-ion collisions at the QCD phase transition. In this note I will summarize the current status of these dynamical models and highlight some of the important issues, which need to be addressed in the future.
On the Associativity of Infinite Matrix Multiplication

A natural definition of the product of infinite matrices mimics the usual formulation of multiplication of finite matrices with the caveat (in the absence of any sense of convergence) that the inte...
Optimal measurement policy for predicting UAV network topology

In recent years, there has been a growing interest in using networks of Unmanned Aerial Vehicles (UAV) that collectively perform complex tasks for diverse applications. An important challenge in realizing UAV networks is the need for a communication platform that accommodates rapid network topology changes. For instance, a timely prediction of network topology changes can reduce communication link loss rate by setting up links with prolonged connectivity. In this work, we develop an optimal tracking policy for each UAV to perceive its surrounding network configuration in order to facilitate more efficient communication protocols. More specifically, we develop an algorithm based on particle swarm optimization and Kalman filtering with intermittent observations to find a set of optimal tracking policies for each UAV under time-varying channel qualities and constrained tracking resources such that the overall network estimation error is minimized.
Twisted representations of vertex operator algebras associated to affine Lie algebras

Abstract In this paper, we prove that the categories of lower bounded twisted modules of positive integer levels for simple vertex operator algebras associated with affine Lie algebras and general automorphisms are semisimple, using the twisted generalizations of Zhu's algebras for these vertex operator algebras, constructed in [13] . We also show that the category of lower bounded twisted modules for a general automorphism is equivalent to the category of lower bounded twisted modules for the corresponding diagram automorphism.
Query-Focused Opinion Summarization for User-Generated Content

We present a submodular function-based framework for query-focused opinion summarization. Within our framework, relevance ordering produced by a statistical ranker, and information coverage with respect to topic distribution and diverse viewpoints are both encoded as submodular functions. Dispersion functions are utilized to minimize the redundancy. We are the first to evaluate different metrics of text similarity for submodularity-based summarization methods. By experimenting on community QA and blog summarization, we show that our system outperforms state-of-the-art approaches in both automatic evaluation and human evaluation. A human evaluation task is conducted on Amazon Mechanical Turk with scale, and shows that our systems are able to generate summaries of high overall quality and information diversity.
Expanding polynomials over finite fields of large characteristic, and a regularity lemma for definable sets

Let $P: \F \times \F \to \F$ be a polynomial of bounded degree over a finite field $\F$ of large characteristic. In this paper we establish the following dichotomy: either $P$ is a \emph{moderate asymmetric expander} in the sense that $|P(A,B)| \gg |\F|$ whenever $A, B \subset \F$ are such that $|A| |B| \geq C |\F|^{2-1/8}$ for a sufficiently large $C$, or else $P$ takes the form $P(x,y) = Q(F(x)+G(y))$ or $P(x,y) = Q(F(x) G(y))$ for some polynomials $Q,F,G$. This is a reasonably satisfactory classification of polynomials of two variables that moderately expand (either symmetrically or asymmetrically). We obtain a similar classification for weak expansion (in which one has $|P(A,A)| \gg |A|^{1/2} |\F|^{1/2}$ whenever $|A| \geq C |\F|^{1-1/16}$), and a partially satisfactory classification for almost strong asymmetric expansion (in which $|P(A,B)| = (1-O(|\F|^{-c})) |\F|$ when $|A|, |B| \geq |\F|^{1-c}$ for some small absolute constant $c>0$). The main new tool used to establish these results is an \emph{algebraic regularity lemma} that describes the structure of dense graphs generated by definable subsets over finite fields of large characteristic. This lemma strengthens the Sz\'emeredi regularity lemma in the algebraic case, in that while the latter lemma decomposes a graph into a bounded number of components, most of which are $\eps$-regular for some small but fixed $\epsilon$, the former lemma ensures that all of the components are $O(|\F|^{-1/4})$-regular. This lemma, which may be of independent interest, relies on some basic facts about the \'etale fundamental group of an algebraic variety.
Integers represented by positive-definite quadratic forms and Petersson inner products

Let $Q$ be a positive-definite quaternary quadratic form with integer coefficients. We study the problem of giving bounds on the largest positive integer $n$ that is locally represented by $Q$ but not represented. Assuming that $n$ is relatively prime to $D(Q)$, the determinant of the Gram matrix of $Q$, we show that $n$ is represented provided that \[ n \gg \max \{ N(Q)^{3/2 + \epsilon} D(Q)^{5/4 + \epsilon}, N(Q)^{2 + \epsilon} D(Q)^{1 + \epsilon} \}. \] Here $N(Q)$ is the level of $Q$. We give three other bounds that hold under successively weaker local conditions on $n$. These results are proven by bounding the Petersson norm of the cuspidal part of the theta series, which is accomplished using an explicit formula for the Weil representation due to Scheithauer.
Kakeya-Nikodym averages and $L^p$-norms of eigenfunctions

We provide a necessary and sufficient condition that $L^p$-norms, $2<p<6$, of eigenfunctions of the square root of minus the Laplacian on two-dimensional compact boundaryless Riemannian manifolds $M$ are small compared to a natural power of the eigenvalue $\lambda$. The condition that ensures this is that their $L^2$-norms over $O(\lambda^{-1/2})$ neighborhoods of arbitrary unit geodesics are small when $\lambda$ is large (which is not the case for the highest weight spherical harmonics on $S^2$ for instance). The proof exploits Gauss' lemma and the fact that the bilinear oscillatory integrals in Hormander's proof of the Carleson-Sjolin theorem become better and better behaved away from the diagonal. Our results are related to a recent work of Bourgain who showed that $L^2$-averages over geodesics of eigenfunctions are small compared to a natural power of the eigenvalue $\lambda$ provided that the $L^4(M)$ norms are similarly small. Our results imply that QUE cannot hold on a compact boundaryless Riemannian manifold $(M,g)$ of dimension two if $L^p$-norms are saturated for a given $2<p<6$. We also show that eigenfunctions cannot have a maximal rate of $L^2$-mass concentrating along unit portions of geodesics that are not smoothly closed.
On the Problem of Minimum Asymptotic Exit Rate for Stochastically Perturbed Multi-Channel Dynamical Systems

We consider the problem of minimizing the asymptotic exit rate with which the controlled-diffusion process of a stochastically perturbed multi-channel dynamical system exits from a given bounded open domain. In particular, for a class of admissible bounded linear feedback operators, we establish a connection between the asymptotic exit rate with which such a controlled-diffusion process exits from the given domain and the asymptotic behavior (i.e., a probabilistic characterization) of the principal eigenvalue of the infinitesimal generator, which corresponds to the stochastically perturbed dynamical system, with zero boundary conditions on the given domain. Finally, we briefly remark on the implication of our result for evaluating the performance of the associated deterministic multi-channel dynamical system, when such a dynamical system is composed with a set of (sub)-optimal admissible linear feedback operators.
Non-negative Ricci curvature on closed manifolds under Ricci flow

In this short paper we show that non-negative Ricci curvature is not preserved under Ricci flow for closed manifolds of dimensions four and above, strengthening a previous result of Knopf for complete non-compact manifolds of bounded curvature. This brings down to four dimensions a similar result Bohm and Wilking have for dimensions twelve and above. Moreover, the manifolds constructed here are manifolds and relate to a question raised by Xiuxiong Chen.
An On-Orbit CubeSat Centrifuge for Asteroid Science and Exploration

There are thousands of asteroids in near-Earth space and millions expected in the Main Belt. They are diverse in their physical properties and compositions. They are also time capsules of the early Solar System making them valuable for planetary science, and are strategic for resource mining, planetary defense/security and as interplanetary depots. But we lack direct knowledge of the geophysical behavior of an asteroid surface under milligravity conditions, and therefore landing on an asteroid and manipulating its surface material remains a daunting challenge. Towards this goal we are putting forth plans for a 12U CubeSat that will be in Low Earth Orbit and that will operate as a spinning centrifuge on-orbit. In this paper, we will present an overview of the systems engineering and instrumentation design on the spacecraft. Parts of this 12U CubeSat will contain a laboratory that will recreate asteroid surface conditions by containing crushed meteorite. The laboratory will spin at 1 to 2 RPM during the primary mission to simulate surface conditions of asteroids 2 km and smaller, followed by an extended mission where the spacecraft will spin at even higher RPM. The result is a bed of realistic regolith, the environment that landers and diggers and maybe astronauts will interact with. The CubeSat is configured with cameras, lasers, actuators and small mechanical instruments to both observe and manipulate the regolith at low simulated gravity conditions. A series of experiments will measure the general behavior, internal friction, adhesion, dilatancy, coefficients of restitution and other parameters that can feed into asteroid surface dynamics simulations. Effective gravity can be varied, and external mechanical forces can be applied. These centrifuge facilities in space will require significantly less resources and budget to maintain, operating in LEO, compared to the voyages to deep space. This means we can maintain a persistent presence in the relevant deep space environment without having to go there. Having asteroid-like centrifuges in LEO would serve the important tactical goal of preparing and maintaining readiness, even when missions are delayed or individual programs get cancelled.
Sharp metric obstructions for quasi-Einstein metrics

Abstract Using the tractor calculus to study smooth metric measure spaces, we adapt results of Gover and Nurowski to give sharp metric obstructions to the existence of quasi-Einstein metrics on suitably generic manifolds. We do this by introducing an analogue of the Weyl tractor W to the setting of smooth metric measure spaces. The obstructions we obtain can be realized as tensorial invariants which are polynomial in the Riemann curvature tensor and its divergence. By taking suitable limits of their tensorial forms, we then find obstructions to the existence of static potentials, generalizing to higher dimensions a result of Bartnik and Tod, and to the existence of potentials for gradient Ricci solitons.
Sequential Equilibrium in Computational Games

We examine sequential equilibrium in the context of computational games (Halpern and Pass 2015), where agents are charged for computation. In such games, an agent can rationally choose to forget, so issues of imperfect recall arise. In this setting, we consider two notions of sequential equilibrium. One is an ex ante notion, where a player chooses his strategy before the game starts and is committed to it, but chooses it in such a way that it remains optimal even off the equilibrium path. The second is an interim notion, where a player can reconsider at each information set whether he is doing the “right” thing, and if not, can change his strategy. The two notions agree in games of perfect recall, but not in games of imperfect recall. Although the interim notion seems more appealing, in a companion article (Halpern and Pass 2016), we argue that there are some deep conceptual problems with it in standard games of imperfect recall. We show that the conceptual problems largely disappear in the computational setting. Moreover, in this setting, under natural assumptions, the two notions coincide.
Analyzing the costs (and benefits) of DNS, DoT, and DoH for the modern web

We measure the effect of DoH and DoT on name resolution performance and content delivery. We find that although DoH and DoT response times can be higher than for conventional DNS (Do53), DoT performs better than DoH and Do53 in terms of page load times. However, when network conditions degrade, webpages load quickest with Do53, and up to one second faster compared to DoH. Furthermore, in a substantial amount of cases, a webpage may not load at all with DoH, while it loads successfully with DoT and Do53. Our in-depth analysis reveals various opportunities to readily improve DNS performance, for example through opportunistic partial responses and wire format caching.
Stability analysis for a class of nonlinear time-changed systems

AbstractThis paper investigates the stability of a class of differential systems time-changed by Et which is the inverse of a β-stable subordinator. In order to explore stability, a time-changed Gronwall’s inequality and a generalized Ito formula related to both the natural time t and the time-change Et are developed. For different time-changed systems, corresponding stability behaviors such as exponential sample-path stability, pth moment asymptotic stability and pth moment exponential stability are investigated. Also a connection between the stability of the time-changed system and that of its corresponding non-time-changed system is revealed.
Universality of the mean-field for the Potts model

We consider the Potts model with q colors on a sequence of weighted graphs with adjacency matrices $$A_n$$ , allowing for both positive and negative weights. Under a mild regularity condition on $$A_n$$ we show that the mean-field prediction for the log partition function is asymptotically correct, whenever $${{\mathrm{tr}}}(A_n^2)=o(n)$$ . In particular, our results are applicable for the Ising and the Potts models on any sequence of graphs with average degree going to $$+\infty $$ . Using this, we establish the universality of the limiting log partition function of the ferromagnetic Potts model for a sequence of asymptotically regular graphs, and that of the Ising model for bi-regular bipartite graphs in both ferromagnetic and anti-ferromagnetic domain. We also derive a large deviation principle for the empirical measure of the colors for the Potts model on asymptotically regular graphs.
Observations of the stratorotational instability in rotating concentric cylinders

Stratified flow between co-rotating vertical cylinders has many similarities with the dynamics observed in stellar and planetary accretion disks: The flow has rotation, anticyclonic shear, and a stabilizing density gradient parallel to the rotation axis. A new experiment extends the scope of previous work and demonstrates inconsistencies with linear instability theory, both viscous and inviscid.
Quantitative asymptotics of graphical projection pursuit

There is a result of Diaconis and Freedman which says that, in a limiting sense, for large collections of high-dimensional data most one-dimensional projections of the data are approximately Gaussian. This paper gives quantitative versions of that result. For a set of $n$ deterministic vectors $\{x_i\}$ in $R^d$ with $n$ and $d$ fixed, let $\theta$ be a random point of the sphere and let $\mu_\theta$ denote the random measure which puts equal mass at the projections of each of the $x_i$ onto the direction $\theta$. For a fixed bounded Lipschitz test function $f$, an explicit bound is derived for the probability that the integrals of $f$ with respect to $\mu_\theta$ and with respect to a suitable Gaussian distribution differ by more than $\epsilon$. A bound is also given for the probability that the bounded-Lipschitz distance between these two measures differs by more than $\epsilon$, which yields a lower bound on the waiting time to finding a non-Gaussian projection of the $x_i$, if directions are tried independently and uniformly.