cssi/SciSciGPT-SciSciNet huggingface dataset:
The Law of Self-Eating—Milk, Placenta, and Feces Consumption

Humans have consumed nearly every human body part. Today, the consumption of milk, placenta, and feces, in particular, is on the rise. Milk, placenta, and feces circulate directly among people given that no medical expertise is required to consume them in unprocessed form, but they are also distributed by institutionalized medical entities (e.g., biobanks, hospitals, pharmaceutical, biotechnology, or cosmetic companies). They are considered simultaneously valuable (as they are typically donated gratuitously and primarily used for nutritional, health, and research purposes) and dangerous (as they can transmit viruses, bacteria, parasites, and pollutants). This article has two main goals. First, in examining the social meanings of milk, placenta, and feces consumption, it considers whether and how the circulation of these bio-commodities shapes the limits of human bodies and communities. Second, it asks whether there is something different or specific about the way in which self-consumption (i.e., the consumption of human body materials by humans) is regulated compared to that of foods, drugs, and supplements derived from animal bodies, plants, or other non-human sources.
To tweet or not to tweet: covertly manipulating a Twitter debate on vaccines using malware-induced misperceptions

Trolling and social bots have been proven as powerful tactics for manipulating the public opinion and sowing discord among Twitter users. This effort requires substantial content fabrication and account coordination to evade Twitter's detection of nefarious platform use. In this paper we explore an alternative tactic for covert social media interference by inducing misperceptions about genuine, non-trolling content from verified users. This tactic uses a malware that covertly manipulates targeted words, hashtags, and Twitter metrics before the genuine content is presented to a targeted user in a covert man-in-the-middle fashion. Early tests of the malware found that it is capable of achieving a similar goal as trolls and social bots, that is, silencing or provoking social media users to express their opinion in polarized debates on social media. Following this, we conducted experimental tests in controlled settings (N = 315) where the malware covertly manipulated the perception in a Twitter debate on the risk of vaccines causing autism. The empirical results demonstrate that inducing misperception is an effective tactic to silence users on Twitter when debating polarizing issues like vaccines. We used the findings to propose a solution for countering the effect of the malware-induced misperception that could also be used against trolls and social bots on Twitter.
No Computation without Representation: Avoiding Data and Algorithm Biases through Diversity

The emergence and growth of research on issues of ethics in Artificial Intelligence, and in particular algorithmic fairness, has roots in an essential observation that structural inequalities in our society are reflected in the data used to train predictive models and in the design of objective functions. While research aiming to mitigate these issues is inherently interdisciplinary, the design of unbiased algorithms and fair socio-technical systems are key desired outcomes which depend on practitioners from the fields of data science and computing. However, these computing fields broadly also suffer from the same under-representation issues that are found in the datasets we analyze. This disconnect affects the design of both the desired outcomes and metrics by which we measure success. If the ethical AI research community accepts this, we tacitly endorse the status quo and contradict the goals of non-discrimination and equity which work on algorithmic fairness, accountability, and transparency seeks to address. Therefore, we advocate in this work for diversifying computing as a core priority of the field and our efforts to achieve ethical AI practices. We draw connections between the lack of diversity within academic and professional computing fields and the type and breadth of the biases encountered in datasets, machine learning models, problem formulations, and the interpretation of results. Examining the current fairness/ethics in AI literature, we highlight cases where this lack of diverse perspectives has been foundational to the inequity in the treatments of underrepresented and protected group data. We also look to other professional communities, such as in the law and health domains, where disparities have been reduced both in the educational diversity of trainees and among their professional practices. We use these lessons to develop a set of key recommendations that provide concrete steps for the computing community to increased diversity: 1) building collaborations with minority serving institutions, 2) prioritizing research collaboration between the ethics in AI community and underrepresented/interdisciplinary groups, and 3) providing enhanced mentorship to trainees at research conferences.
The idea of a human rights-based economic recovery after COVID-19

The COVID-19 pandemic has produced a health and economic crisis of unprecedented scope. As economists and policymakers turn to the task of recovery, protecting human rights remains intrinsically important, both morally and legally. It is also instrumental to the ends of public health and economic resilience. This article argues that the human rights to life, health, education, social security, housing, food, water and sanitation - among the so-called economic and social rights - are as essential as civil and political protections. Moreover, rather than simply ameliorate the inevitable indignities and material deprivations caused by the COVID-19 pandemic, the implementation of duties to respect economic and social rights should help ensure their protection in the post-COVID-19 economy. For this to occur, however, the article suggests that the application of human rights to the economic recovery must be informed by a longer history of economic crises and be assisted by both international and comparative economic and social rights legal frameworks and participatory processes.
Embedding Information in Radiation Pattern Fluctuations

The radiation pattern of transmit antennas varies and fluctuates as receivers change their location, other objects move around, and due to the antenna design itself. In this paper, we demonstrate how this observation can be exploited to align most of the interference signal power and significantly increase the average achievable communication rates. More precisely, in the context of K-user interference channels, we propose a blind interference alignment scheme that combines multi-layer coding at the transmitters and a post-processing methodology at the receivers to align a significant portion of the interference signal power. Our scheme does not rely on any channel state information (CSI), hence the term blind, and only relies on the statistics of the radiation pattern fluctuations. Our proposed communication methodology overcomes some of the barriers in practical implementation of the interference alignment concept. Due to the complexity of the expressions, in this work, we numerically evaluate the achievable rates in different scenarios, demonstrate the gains of our proposed strategy, and compare our results to the prior works with perfect CSI.
JT gravity at finite cutoff

We compute the partition function of $2D$ Jackiw-Teitelboim (JT) gravity at finite cutoff in two ways: (i) via an exact evaluation of the Wheeler-DeWitt wave-functional in radial quantization and (ii) through a direct computation of the Euclidean path integral. Both methods deal with Dirichlet boundary conditions for the metric and the dilaton. In the first approach, the radial wavefunctionals are found by reducing the constraint equations to two first order functional derivative equations that can be solved exactly, including factor ordering. In the second approach we perform the path integral exactly when summing over surfaces with disk topology, to all orders in perturbation theory in the cutoff. Both results precisely match the recently derived partition function in the Schwarzian theory deformed by an operator analogous to the $T\bar{T}$ deformation in $2D$ CFTs. This equality can be seen as concrete evidence for the proposed holographic interpretation of the $T\bar{T}$ deformation as the movement of the AdS boundary to a finite radial distance in the bulk.
Robust Spammer Detection by Nash Reinforcement Learning

Online reviews provide product evaluations for customers to make decisions. Unfortunately, the evaluations can be manipulated using fake reviews ("spams") by professional spammers, who have learned increasingly insidious and powerful spamming strategies by adapting to the deployed detectors. Spamming strategies are hard to capture, as they can be varying quickly along time, different across spammers and target products, and more critically, remained unknown in most cases. Furthermore, most existing detectors focus on detection accuracy, which is not well-aligned with the goal of maintaining the trustworthiness of product evaluations. To address the challenges, we formulate a minimax game where the spammers and spam detectors compete with each other on their practical goals that are not solely based on detection accuracy. Nash equilibria of the game lead to stable detectors that are agnostic to any mixed detection strategies. However, the game has no closed-form solution and is not differentiable to admit the typical gradient-based algorithms. We turn the game into two dependent Markov Decision Processes (MDPs) to allow efficient stochastic optimization based on multi-armed bandit and policy gradient. We experiment on three large review datasets using various state-of-the-art spamming and detection strategies and show that the optimization algorithm can reliably find an equilibrial detector that can robustly and effectively prevent spammers with any mixed spamming strategies from attaining their practical goal. Our code is available at https://github.com/YingtongDou/Nash-Detect.
A Structured Mentorship Elective Deepens Personal Connections and Increases Scholarly Achievements of Senior Surgery Residents.

Objectives Surgery residents have few opportunities to work closely with attending surgeons or conduct research during clinical time. We hypothesized that a mentorship elective with a required research project would benefit residents’ career development, including their personal connections with faculty mentors, and would help them build their academic portfolio. Design We created a mentorship elective designed as a one-on-one apprenticeship. Completion of a scholarly project was a core component of the elective. Residents, faculty, and the most senior resident (‘non-mentee’) on the same service as the elective resident were interviewed after the completion of their rotation. Setting University-based surgery residency at Boston Medical Center, Boston, MA. Participants All 5 residents in postgraduate year 4 (PGY-4) participated in the mentorship elective during the 2019 to 2020 academic year. Residents identified their faculty mentor. All mentees (5/5), most mentors (4/5), and all non-mentees (4/4) were interviewed. Results All mentees reported interacting with their mentor daily, performing clinical duties or discussing their research project. For mentees, the top factor when selecting their mentor was the mentor's clinical expertise, and the most valuable aspect of the rotation was developing a relationship with their mentor. All mentors responded that their mentee gained an understanding of running an academic surgical practice and developed research skills. Four of 5 mentees completed critical portions of their scholarly project during the elective with one publishing in a peer-reviewed journal, 2 having their work accepted to a national conference, and one creating vascular surgery educational videos. All stated the elective was valuable. Conclusions A structured apprenticeship rotation allowed for closer relationships with attending surgeons and increased the scholarly achievement of PGY-4 surgery residents. We provide an example of how to incorporate a successful elective rotation into the surgery curriculum that strengthens resident career development and research productivity.
LICENSING AND THE INFORMAL SECTOR IN RENTAL HOUSING MARKETS: THEORY AND EVIDENCE

Although the goal of licensing is to ensure the quality of services, it can also induce firms to operate informally or exit altogether. This paper examines licensing in the rental housing market by developing a model that indicates licensing's impact on the size of the underground rental market, the number of vacancies, and homelessness are ambiguous. As a result, we calibrate the model using a unique dataset from Baltimore, which allows us to directly observe underground rentals and vacancies. Our calibrations show that licensing may have a modest impact on rents, while increasing quality more substantially.
Translating Neuralese

Several approaches have recently been proposed for learning decentralized deep multiagent policies that coordinate via a differentiable communication channel. While these policies are effective for many tasks, interpretation of their induced communication strategies has remained a challenge. Here we propose to interpret agents’ messages by translating them. Unlike in typical machine translation problems, we have no parallel data to learn from. Instead we develop a translation model based on the insight that agent messages and natural language strings mean the same thing if they induce the same belief about the world in a listener. We present theoretical guarantees and empirical evidence that our approach preserves both the semantics and pragmatics of messages by ensuring that players communicating through a translation layer do not suffer a substantial loss in reward relative to players with a common language.
PARTITION OF RECOMBINATION ENERGY IN THE DECAYING RARE-GAS PLASMAS.

In the collisional-radiative electron-ion recombination regime, the energy liberated from each recombination is partly carried away by a third colliding free electron and partly transformed into radiation. The partition of the energy among the electrons and radiation is obtained by comparing the probability of electron collisional de-excitation at different atomic-energy states, calculated by using Gryzi\ifmmode \acute{n}\else \'{n}\fi{}ski's formulation, and the spontaneous transition probability of bound electrons to all lower states evaluated by using the sum rule of line strength and the central-field approximation. A recombination-dominated decaying plasma is produced by a discharge tube energized with a capacitor bank. After cessation of the discharge current, the electron density, electron temperature, and atom temperature are measured by using both microwave and electrostatic probes, the spectral-line ratio method, and a fast-rise-time resistance thermometer, respectively. The partition of the recombination energy under different conditions for He, Ne, Ar, Kr, and Xe gases is determined from a solution of the electron-energy equation. The experimental results are in good agreement with the theoretical predictions. The oscillator strengths of the resonance lines for the five rare gases are also presented.
The isoperimetric inequality for a minimal submanifold in Euclidean space

We prove a Sobolev inequality which holds on submanifolds in Euclidean space of arbitrary dimension and codimension. This inequality is sharp if the codimension is at most 2. As a special case, we obtain a sharp isoperimetric inequality for minimal submanifolds in Euclidean space of codimension at most 2.
Chapter 39 – Animal Models for Osteoporosis

Animal models have aided our understanding of the pathophysiology and treatment of osteoporosis. They have been an especially useful tool for investigating interactions between multiple risk factors, such as aging, hormonal interactions, and genetic predisposition toward bone fragility. Animals are indispensable for preclinical evaluation of the efficacy and safety of interventions intended to prevent and/or reverse bone fragility, and they have successfully identified detrimental as well as the beneficial skeletal actions of a wide variety of drugs. Without animal models, it is questionable whether current osteoporosis therapies would have reached clinical practice.
An evolutionarily acquired microRNA shapes development of mammalian cortical projections

The corticospinal tract is unique to mammals and the corpus callosum is unique to placental mammals (eutherians). The emergence of these structures is thought to underpin the evolutionary acquisition of complex motor and cognitive skills. Corticospinal motor neurons (CSMN) and callosal projection neurons (CPN) are the archetypal projection neurons of the corticospinal tract and corpus callosum, respectively. Although a number of conserved transcriptional regulators of CSMN and CPN development have been identified in vertebrates, none are unique to mammals and most are coexpressed across multiple projection neuron subtypes. Here, we discover 17 CSMN-enriched microRNAs (miRNAs), 15 of which map to a single genomic cluster that is exclusive to eutherians. One of these, miR-409-3p, promotes CSMN subtype identity in part via repression of LMO4, a key transcriptional regulator of CPN development. In vivo, miR-409-3p is sufficient to convert deep-layer CPN into CSMN. This is a demonstration of an evolutionarily acquired miRNA in eutherians that refines cortical projection neuron subtype development. Our findings implicate miRNAs in the eutherians' increase in neuronal subtype and projection diversity, the anatomic underpinnings of their complex behavior.
Balanced Convex Partitions of Lines in the Plane

We prove an extension of a ham sandwich theorem for families of lines in the plane by Dujmovic and Langerman. Given two sets A, B of n lines each in the plane, we prove that it is possible to partition the plane into r closed convex regions so that the following holds. For each region C of the partition there is a subset of $$c_r n^{1/r}$$ lines of A whose pairwise intersections are in C, and the same holds for B. In this statement $$c_r$$ only depends on r. We also prove that the dependence on n is optimal. For a single set A of n lines, we prove that there exists a partition of the plane into r parts using $$r-1$$ vertical lines such that each region contains the pairwise intersections of a set of $$n^{1/r}$$ lines of A. The value $$n^{1/r}$$ is optimal.
Dynamic pricing and fleet management for electric autonomous mobility on demand systems

Abstract The proliferation of ride sharing systems is a major drive in the advancement of autonomous and electric vehicle technologies. This paper considers the joint routing, battery charging, and pricing problem faced by a profit-maximizing transportation service provider that operates a fleet of autonomous electric vehicles. We first establish the static planning problem by considering time-invariant system parameters and determine the optimal static policy. While the static policy provides stability of customer queues waiting for rides even if consider the system dynamics, we see that it is inefficient to utilize a static policy as it can lead to long wait times for customers and low profits. To accommodate for the stochastic nature of trip demands, renewable energy availability, and electricity prices and to further optimally manage the autonomous fleet given the need to generate integer allocations, a real-time policy is required. The optimal real-time policy that executes actions based on full state information of the system is the solution of a complex dynamic program. However, we argue that it is intractable to exactly solve for the optimal policy using exact dynamic programming methods and therefore apply deep reinforcement learning to develop a near-optimal control policy. The two case studies we conducted in Manhattan and San Francisco demonstrate the efficacy of our real-time policy in terms of network stability and profits, while keeping the queue lengths up to 200 times less than the static policy.
Pointwise Bounds and Blow-up for Nonlinear Polyharmonic Inequalities

Abstract We obtain results for the following question where m ⩾ 1 and n ⩾ 2 are integers. Question For which continuous functions f : [ 0 , ∞ ) → [ 0 , ∞ ) does there exist a continuous function φ : ( 0 , 1 ) → ( 0 , ∞ ) such that every C 2 m nonnegative solution u ( x ) of 0 ⩽ − Δ m u ⩽ f ( u ) in B 2 ( 0 ) ∖ { 0 } ⊂ R n satisfies u ( x ) = O ( φ ( | x | ) ) as x → 0 and what is the optimal such φ when one exists?
Resonance of basis-conjugating automorphism groups

Abstract. We determine the structure of the ﬁrst resonance variety of the coho-mology ring of the group of automorphisms of a ﬁnitely generated free group whichact by conjugation on a given basis. 1. Resonance of PΣ n Let F n be the free group generated by x 1 ,...,x n . The basis-conjugating auto-morphism group, or pure symmetric automorphism group, is the group PΣ n of allautomorphisms of F n which send each generator x i to a conjugate of itself. Results ofDahm [4] and Goldsmith [6] imply that this group may also be realized as the “groupof loops,” the group of motions of a collection of nunknotted, unlinked oriented cir-cles in 3-space, where each circle returns to its original position. McCool [8] found thefollowing presentation for the basis-conjugating automorphism group:(1) PΣ n = hβ i,j ,1 ≤ i6= j≤ n| [β i,j ,β k,l ],[β i,k ,β j,k ],[β i,j ,(β i,k · β j,k )]i,where [u,v] = uvu −1 v −1 denotes the commutator, the indices in the relations aredistinct, and the generators β i,j are the automorphisms of F
ECLIPSING BINARY STARS AS BENCHMARKS FOR TRIGONOMETRIC PARALLAXES IN THE GAIA ERA

We present fits to the broadband photometric spectral energy distributions (SEDs) of 158 eclipsing binaries (EBs) in the Tycho-2 catalog. These EBs were selected because they have highly precise stellar radii, effective temperatures, and in many cases metallicities previously determined in the literature, and thus have bolometric luminosities that are typically good to 10%. In most cases the available broadband photometry spans a wavelength range 0.4–10 μm, and in many cases spans 0.15–22 μm. The resulting SED fits, which have only extinction as a free parameter, provide a virtually model-independent measure of the bolometric flux at Earth. The SED fits are satisfactory for 156 of the EBs, for which we achieve typical precisions in the bolometric flux of ≈3%. Combined with the accurately known bolometric luminosity, the result for each EB is a predicted parallax that is typically precise to 5%. These predicted parallaxes—with typical uncertainties of 200 μas—are 4–5 times more precise than those determined by Hipparcos for 99 of the EBs in our sample, with which we find excellent agreement. There is no evidence among this sample for significant systematics in the Hipparcos parallaxes of the sort that notoriously afflicted the Pleiades measurement. The EBs are distributed over the entire sky, span more than 10 mag in brightness, reach distances of more than 5 kpc, and in many cases our predicted parallaxes should also be more precise than those expected from the Gaia first data release. The EBs studied here can thus serve as empirical, independent benchmarks for these upcoming fundamental parallax measurements.
Degenerations of toric varieties over valuation rings

We develop a theory of multi-stage degenerations of toric varieties over finite rank valuation rings, extending the Mumford--Gubler theory in rank one. Such degenerations are constructed from fan-like structures over totally ordered abelian groups of finite rank. Our main theorem describes the geometry of successive special fibers in the degeneration in terms of the polyhedral geometry of a system of recession complexes associated to the fan.
Mahler Measures as Linear Combinations of $L$-values of Multiple Modular Forms

We study the Mahler measures of certain families of Laurent polynomials in two and three variables. Each of the known Mahler measure formulas for these families involves –values of at most one newform and/or at most one quadratic character. In this paper we show, either rigorously or numerically, that the Mahler measures of some polynomials are related to –values of multiple newforms and quadratic characters simultaneously. The results suggest that the number of modular –values appearing in the formulas significantly depends on the shape of the algebraic value of the parameter chosen for each polynomial. As a consequence, we also obtain new formulas relating special values of hypergeometric series evaluated at algebraic numbers to special values of –functions.
Equivalence of total force (and torque) for two formulations of the Lorentz law

Two formulations of the Lorentz law of force in classical electrodynamics yield identical results for the total force (and total torque) of radiation on a solid object. The object may be surrounded by the free space or immersed in a transparent dielectric medium such as a liquid. We discuss the relation between these two formulations and extend the proof of their equivalence to the case of solid objects immersed in a transparent medium.
Identifying products in online cybercrime marketplaces: A Dataset for fine-grained domain adaptation

One weakness of machine-learned NLP models is that they typically perform poorly on out-of-domain data. In this work, we study the task of identifying products being bought and sold in online cybercrime forums, which exhibits particularly challenging cross-domain effects. We formulate a task that represents a hybrid of slot-filling information extraction and named entity recognition and annotate data from four different forums. Each of these forums constitutes its own “fine-grained domain” in that the forums cover different market sectors with different properties, even though all forums are in the broad domain of cybercrime. We characterize these domain differences in the context of a learning-based system: supervised models see decreased accuracy when applied to new forums, and standard techniques for semi-supervised learning and domain adaptation have limited effectiveness on this data, which suggests the need to improve these techniques. We release a dataset of 1,938 annotated posts from across the four forums.
The Effect of the Dust Size Distribution on Asteroid Polarization

We have developed a theoretical description of how of an asteroid’s polarizationphase curve will be affected by the removal of the dust from the surface due to a sizedependent phenomenon such as radiation pressure-driven escape of levitated particles. We test our calculations against new observations of four small (D � 1 km) nearEarth asteroids [(85236), (142348), (162900) and 2006 SZ217] obtained with the Dual Beam Imaging Polarimeter on the University of Hawaii’s 2.2 m telescope, as well as previous observations of (25143) Itokawa and (433) Eros. We find that the polarization of the light reflected from an asteroid is controlled by the mineralogical and chemical composition of the surface and is independent of dust particle. The relation between the slope of the polarization-phase curve beyond the inversion angle and the albedo of an asteroid is thus independent of the surface regolith size distribution and is valid for both Main Belt and Near-Earth asteroids.
HST's hunt for intermediate-mass black holes in star clusters

Establishing or ruling out, either through solid mass measurements or upper limits, the presence of intermediate-mass black holes (IMBHs; with masses of 102 − 105 M⊙) at the centers of star clusters would profoundly impact our understanding of problems ranging from the formation and long-term dynamical evolution of stellar systems, to the nature of the seeds and the growth mechanisms of supermassive black holes. While there are sound theoretical arguments both for and against their presence in today's clusters, observational studies have so far not yielded truly conclusive IMBH detections nor upper limits. We argue that the most promising approach to solving this issue is provided by the combination of measurements of the proper motions of stars at the centers of Galactic globular clusters and dynamical models able to take full advantage of this type of data set. We present a program based on HST observations and recently developed tools for dynamical analysis designed to do just that.
THE MSSM ON THE INTERVAL

We review electroweak symmetry breaking in supersymmetric models with a compact fifth dimension, the interval. We show how boundary conditions for hypermultiplets can be obtained dynamically by brane mass terms, and present formulas for the spectrum in the presence of general bulk mass matrices. After giving a brief overview on the literature of models, we describe in detail a recently proposed model that at energies below the compactification scale reduces to the MSSM with a very peculiar superpartner spectrum.
Star Formation with Adaptive Mesh Refinement Radiation Hydrodynamics

I provide a pedagogic review of adaptive mesh refinement (AMR) radiation hydrodynamics (RHD) methods and codes used in simulations of star formation, at a level suitable for researchers who are not computational experts. I begin with a brief overview of the types of RHD processes that are most important to star formation, and then I formally introduce the equations of RHD and the approximations one uses to render them computationally tractable. I discuss strategies for solving these approximate equations on adaptive grids, with particular emphasis on identifying the main advantages and disadvantages of various approximations and numerical approaches. Finally, I conclude by discussing areas ripe for improvement.
Spontaneous parametric down conversion with a depleted pump as an analogue for black hole evaporation/particle production

In this work we argue that black hole evaporation/particle production has a very close analogy to the laboratory process of spontaneous parametric down conversion, when the pump is allowed to deplete. We present an analytical formulation of the recent one-shot decoupling model that was numerically analyzed in Bradler and Adami Phys. Rev. Lett. 116, 101301 (2016) [arXiv:1505.0284]. We compute the resulting "Page Information" curves, which describe the rate at which information escapes form the black hole as it evaporates, for the reduced density matrices for the evaporating black hole internal degrees of freedom, and emitted Hawking radiation pairs entangled across the horizon. The present work reviews and attempts to elucidate the trilinear Hamiltonian models for black hole evaporation/particle production recently investigated by the authors in Class. Quant. Grav 32, 075010 (2015) [arXiv:1408.4491] and Class. Quant. Grav 33, 015005 (2016) [arXiv:1507.00429].
Convex cocompactness and stability in mapping class groups

We introduce a strong notion of quasiconvexity in finitely generated groups, which we call stability. Stability agrees with quasiconvexity in hyperbolic groups and is preserved under quasi-isometry for finitely generated groups. We show that the stable subgroups of mapping class groups are precisely the convex cocompact subgroups. This generalizes a well-known result of Behrstock and is related to questions asked by Farb and Mosher and by Farb. 20F65, 51H05; 57M07, 30F60
Deep Imaging of M51: a New View of the Whirlpool’s Extended Tidal Debris

We present deep, wide-field imaging of the M51 system using CWRU’s Burrell Schmidt Telescope at KPNO to study the faint tidal features that constrain its interaction history. Our images trace M51's tidal morphology down to a limiting surface brightness of μB,lim ∼ 30 mag arcsec−2 and provide accurate colors () down to μB ∼ 28. We identify two new tidal streams in the system (the south and northeast plumes) with surface brightnesses of μB = 29 and luminosities of ∼106L⊙,B. While the northeast plume may be a faint outer extension of the tidal “crown” north of NGC 5195 (M51b), the south plume has no analog in any existing M51 simulation and may represent a distinct tidal stream or disrupted dwarf galaxy. We also trace the extremely diffuse northwest plume out to a total extent of 20′ (43 kpc) from NGC 5194 (M51a) and show it to be physically distinct from the overlapping bright tidal streams from M51b. The northwest plume’s morphology and red color () instead argue that it originated from tidal stripping of M51a’s extreme outer disk. Finally, we confirm the strong segregation of gas and stars in the southeast tail and do not detect any diffuse stellar component in the H i portion of the tail. Extant simulations of M51 have difficulty matching both the wealth of tidal structure in the system and the lack of stars in the H i tail, motivating new modeling campaigns to study the dynamical evolution of this classic interacting system.
Meron-cluster simulation of a chiral phase transition with staggered fermions☆

Abstract We examine a (3+1) -dimensional model of staggered lattice fermions with a four-fermion interaction and Z (2) chiral symmetry using the Hamiltonian formulation. This model cannot be simulated with standard fermion algorithms because those suffer from a very severe sign problem. We use a new fermion simulation technique — the meron-cluster algorithm — which solves the sign problem and leads to high-precision numerical data. We investigate the finite temperature chiral phase transition and verify that it is in the universality class of the 3-d Ising model using finite-size scaling.
Necessary and Sufficient Conditions for Frequency-Based Kelly Optimal Portfolio

In this letter, we consider a discrete-time portfolio with m ≥ 2 assets optimization problem which includes the rebalancing frequency as an additional parameter in the maximization. The so-called Kelly Criterion is used as the performance metric; i.e., maximizing the expected logarithmic growth of a trader's account, and the portfolio obtained is called the frequency-based Kelly optimal portfolio. The focal point of this letter is to extend upon the results of our previous work to obtain various optimality characterizations on the portfolio. To be more specific, using Kelly's criterion in our new frequency-based formulation, we first prove necessary and sufficient conditions for the frequency-based Kelly optimal portfolio. With the aid of these conditions, we then show several new optimality characterizations such as expected ratio optimality and asymptotic relative optimality, and a result which we call the Extended Dominant Asset Theorem. That is, we prove that the ith asset is dominant in the portfolio if and only if the Kelly optimal portfolio consists of that asset only. The word “extended” on the theorem comes from the fact that it was only a sufficiency result that was proved in our previous work. Hence, in this letter, we improve it to involve a proof of the necessity part. In addition, the trader's survivability issue (no bankruptcy consideration) is also studied in detail in our frequency-based trading framework. Finally, to bridge the theory and practice, we propose a simple trading algorithm using the notion called dominant asset condition to decide when should one triggers a trade. The corresponding trading performance using historical price data is reported as supporting evidence.
A cube of resolutions for knot Floer homology

We develop a skein exact sequence for knot Floer homology, involving singular knots. This leads to an explicit, algebraic description of knot Floer homology in terms of a braid projection of the knot.
Non-negative matrix factorization test cases

Non-negative matrix factorization (NMF) is a problem with many applications, ranging from facial recognition to document clustering. However, due to the variety of algorithms that solve NMF, the randomness involved in these algorithms, and the somewhat subjective nature of the problem, there is no clear “correct answer” to any particular NMF problem, and as a result, it can be hard to test new algorithms. In this paper, we suggest some test cases for NMF algorithms derived from matrices with enumerable exact non-negative factorizations and perturbations of these matrices. We show that three algorithms using widely divergent approaches to NMF all give similar solutions over these test cases, so they can be used as benchmarks for new algorithms. We also describe how the proposed test cases ought to be used.
Lattice vibrational modes and Raman scattering spectra of strained phosphorene

Strain is prominent in fabricated samples and it also serves as an exploitable tool for engineering their properties. However, quantifying strain and characterizing its spatially inhomogeneous distribution are challenging tasks. Here, we report the lattice vibrational modes and corresponding Raman spectra of strained monolayer black phosphorus (phosphorene) by first-principles simulations. We show that frequencies of vibrational modes of phosphorene and their Raman scattering peaks exhibit substantial and distinct shifts according to the types and size of strain. Combined with high spatial-resolution Raman scattering measurements, our calculated results can quantify arbitrary strain distributions in phosphorene.
Optimal Control of Multiphase Free Boundary Problems for Nonlinear Parabolic Equations

We consider the optimal control of singular nonlinear partial differential equation which is the distributional formulation of the multiphase Stefan type free boundary problem for the general second order parabolic equation. Boundary heat flux is the control parameter, and the optimality criteria consist of the minimization of the $$L_2$$ -norm difference of the trace of the solution to the PDE problem at the final moment from the given measurement. Sequence of finite-dimensional optimal control problems is introduced through finite differences. We establish existence of the optimal control and prove the convergence of the sequence of discrete optimal control problems to the original problem both with respect to functional and control. Proofs rely on establishing a uniform $$L_{\infty }$$ bound, and $$W_2^{1,1}$$ -energy estimate fo the discrete nonlinear PDE problem with discontinuous coefficient.
Femtosecond-laser-induced spin-polarized electron emission from a GaAs tip

It is shown that focusing circularly polarized 800 nm light pulses of duration 100 fs on the tips of p-GaAs crystalline shards having no negative electron affinity (NEA) activation results in electron emission that is both fast and spin-polarized. The 400 fs duration of the emission process was determined by pump/probe measurements. The three samples we investigated produced electron polarizations of 13.1(0.9)%, 13.3(0.7)%, and 10.4(0.2)%. Emission currents ranged between 50 pA and 3 nA with a sample bias of −100 V and an average laser power of 100 mW. The electron emission exhibited linear dichroism and was obtained under moderate vacuum conditions, similar to that of metallic tips. This source of spin-polarized electron pulses is “fast” in the sense that the electron emission process is of comparable duration to the laser pulses that initiate it.It is shown that focusing circularly polarized 800 nm light pulses of duration 100 fs on the tips of p-GaAs crystalline shards having no negative electron affinity (NEA) activation results in electron emission that is both fast and spin-polarized. The 400 fs duration of the emission process was determined by pump/probe measurements. The three samples we investigated produced electron polarizations of 13.1(0.9)%, 13.3(0.7)%, and 10.4(0.2)%. Emission currents ranged between 50 pA and 3 nA with a sample bias of −100 V and an average laser power of 100 mW. The electron emission exhibited linear dichroism and was obtained under moderate vacuum conditions, similar to that of metallic tips. This source of spin-polarized electron pulses is “fast” in the sense that the electron emission process is of comparable duration to the laser pulses that initiate it.
Entanglement Bounds in the XXZ Quantum Spin Chain

We consider the XXZ spin chain, characterized by an anisotropy parameter $$\Delta >1$$ , and normalized such that the ground state energy is 0 and the ground state given by the all-spins-up state. The energies $$E_K = K(1-1/\Delta )$$ , $$K=1,2,\ldots $$ , can be interpreted as K-cluster breakup thresholds for down-spin configurations. We show that, for every K, the bipartite entanglement of all states with energy below the $$(K+1)$$ -cluster breakup satisfies a log-corrected area law. This generalizes a result by Beaud and Warzel, who considered energies in the droplet spectrum (i.e., below the 2-cluster breakup). For general K, we find an upper logarithmic bound with pre-factor $$2K-1$$ . We show that this constant is optimal in the Ising limit $$\Delta =\infty $$ . Beaud and Warzel also showed that after introducing a random field and disorder averaging the log-corrected area law becomes a strict area law, again for states in the droplet regime. For the Ising limit with random field, we show that this result does not extend beyond the droplet regime. Instead, we find states with energies of an arbitrarily small amount above the K-cluster breakup whose entanglement satisfies a logarithmically growing lower bound with pre-factor $$K-1$$ .
A Complete Uniform Substitution Calculus for Differential Dynamic Logic

This article introduces a relatively complete proof calculus for differential dynamic logic (dL) that is entirely based on uniform substitution, a proof rule that substitutes a formula for a predicate symbol everywhere. Uniform substitutions make it possible to use axioms instead of axiom schemata, thereby substantially simplifying implementations. Instead of subtle schema variables and soundness-critical side conditions on the occurrence patterns of logical variables to restrict infinitely many axiom schema instances to sound ones, the resulting calculus adopts only a finite number of ordinary dLformulas as axioms, which uniform substitutions instantiate soundly. The static semantics of differential dynamic logic and the soundness-critical restrictions it imposes on proof steps is captured exclusively in uniform substitutions and variable renamings as opposed to being spread in delicate ways across the prover implementation. In addition to sound uniform substitutions, this article introduces differential forms for differential dynamic logic that make it possible to internalize differential invariants, differential substitutions, and derivatives as first-class axioms to reason about differential equations axiomatically. The resulting axiomatization of differential dynamic logic is proved to be sound and relatively complete.
Coherent control for qubit state readout

Short pulses from mode-locked lasers can produce background-free atomic fluorescence by allowing temporal separation of the prompt incidental scatter from the subsequent atomic emission. We use this to improve our quantum state detection of optical-frequency and electron-shelved trapped ion qubits by more than 2 orders of magnitude. For direct detection of qubits defined on atomic hyperfine structure, however, the large bandwidth of short pulses is greater than the hyperfine splitting, and repeated excitation is not qubit state selective. Here, we show that the state resolution needed for projective quantum measurement of hyperfine qubits can be recovered by applying techniques from coherent control to the orbiting valence electron of the queried ion. We demonstrate electron wavepacket interference to allow readout of the original qubit state using broadband pulses, even in the presence of large amounts of background laser scatter.
Destruction or preservation as you like it

Abstract The Gap Forcing Theorem, a key contribution of this paper, implies essentially that after any reverse Easton iteration of closed forcing, such as the Laver preparation, every supercompactness measure on a supercompact cardinal extends a measure from the ground model. Thus, such forcing can create no new supercompact cardinals, and, if the GCH holds, neither can it increase the degree of supercompactness of any cardinal; in particular, it can create no new measurable cardinals. In a crescendo of what I call exact preservation theorems, I use this new technology to perform a kind of partial Laver preparation, and thereby finely control the class of posets which preserve a supercompact cardinal. Eventually, I prove the ‘As You Like It’ Theorem, which asserts that the class of κ -directed closed posets which preserve a supercompact cardinal κ can be made by forcing to conform with any pre-selected local definition which respects the equivalence of forcing. Along the way I separate completely the levels of the superdestructibility hierarchy, and, in an epilogue, prove that the notions of fragility and superdestructibility are orthogonal — all four combinations are possible.
Knot homology groups from instantons

1.1 An observation of some coincidences For a knot or link K in S, the Khovanov homology Kh.K/ is a bigraded abelian group whose construction can be described in entirely combinatorial terms [15]. If we forget the bigrading, then as abelian groups we have, for example, Kh.unknot/ D Z and Kh.trefoil/ D Z Z=2: The second equality holds for both the rightand left-handed trefoils, though the bigrading would distinguish these two cases. The present paper was motivated in large part by the observation that the group Z Z=2 arises in a different context. Pick a basepoint y0 in the complement of the knot or link, and consider the space of all homomorphisms
Ground states for exponential random graphs

We propose a perturbative method to estimate the normalization constant in exponential random graph models as the weighting parameters approach infinity. As an application, we give evidence of discontinuity in natural parametrization along the critical directions of the edge-triangle model.
Earth as an Exoplanet: A Two-dimensional Alien Map

Resolving spatially varying exoplanet features from single-point light curves is essential for determining whether Earth-like worlds harbor geological features and/or climate systems that influence habitability. To evaluate the feasibility and requirements of this spatial-feature resolving problem, we present an analysis of multi-wavelength single-point light curves of Earth, where it plays the role of a proxy exoplanet. Here, ~10,000 Deep Space Climate Observatory/Earth Polychromatic Imaging Camera frames collected over a two-year period were integrated over the Earth's disk to yield a spectrally dependent point source and analyzed using singular value decomposition. We found that, between the two dominant principal components (PCs), the second PC contains surface-related features of the planet, while the first PC mainly includes cloud information. We present the first two-dimensional (2D) surface map of Earth reconstructed from light curve observations without any assumptions of its spectral properties. This study serves as a baseline for reconstructing the surface features of Earth-like exoplanets in the future.
Efficient Mobility-on-Demand System with Ride-Sharing

An algorithm to cluster mobility-on-demand trips considering road network structure is developed in this paper. The benefits of our network partition algorithm are demonstrated in numerical simulations, showing that we can use fewer vehicles and can serve more customers with slightly longer wait time by including predicted future travel demand in trip assignment, compared with the benchmark reactive control policy.