cssi/SciSciGPT-SciSciNet huggingface dataset:
A Logistic Model for Age-Specific COVID-19 Case-Fatality Rates

To develop a mathematical model to characterize age-specific case-fatality rates (CFR) of COVID-19. Based on 2 large-scale Chinese and Italian CFR data, a logistic model was derived to provide quantitative insight on the dynamics between CFR and age. We inferred that CFR increased faster in Italy than in China, as well as in females over males. In addition, while CFR increased with age, the rate of growth eventually slowed down, with a predicted theoretical upper limit for males (32%), females (21%), and the general population (23%). Our logistic model provided quantitative insight on the dynamics of CFR.
Random Set Framework for Context-Based Classification With Hyperspectral Imagery

In remotely sensed hyperspectral imagery, many samples are collected on a given flight and many variable factors contribute to the distribution of samples. Various factors transform spectral responses causing them to appear differently in different contexts. We develop a method that infers context via spectra population distribution analysis. In this manner, feature space orientations of sets of spectral signatures are characterized using random set models. The models allow for the characterization of complex and irregular patterns in a feature space. The developed random set framework for context-based classification applies context-specific classifiers in an ensemblelike manner, and aggregates their decisions based on their contextual relevance to the spectra under test. Results indicate that the proposed method improves classification accuracy over similar classifiers, which make no use of contextual information, and performs well when compared to similar context-based approaches.
Geometry of the graphs of nonseparating curves: covers and boundaries

We investigate the geometry of the graphs of nonseparating curves for surfaces of finite positive genus with potentially infinitely many punctures. This graph has infinite diameter and is known to be Gromov hyperbolic by work of the author. We study finite covers between such surfaces and show that lifts of nonseparating curves to the nonseparating curve graph of the cover span quasiconvex subgraphs which are infinite diameter and not coarsely equal to the nonseparating curve graph of the cover. In the finite type case, we also reprove a theorem of Hamenstadt identifying the Gromov boundary with the space of ending laminations on full genus subsurfaces. We introduce several tools based around the analysis of bicorn curves and laminations which may be of independent interest for studying the geometry of nonseparating curve graphs of infinite type surfaces and their boundaries.
On Grids in Point-Line Arrangements in the Plane

The famous Szemeredi–Trotter theorem states that any arrangement of n points and n lines in the plane determines $$O(n^{4/3})$$ incidences, and this bound is tight. In this paper, we prove the following Turan-type result for point-line incidence. Let $$\mathcal {L}_a$$ and $$\mathcal {L}_b$$ be two sets of t lines in the plane and let $$P=\{\ell _a \cap \ell _b : \ell _a \in \mathcal {L}_a, \,\ell _b \in \mathcal {L}_b\}$$ be the set of intersection points between $$\mathcal {L}_a$$ and $$\mathcal {L}_b$$ . We say that $$(P, \mathcal {L}_a \cup \mathcal {L}_b)$$ forms a natural $$t\times t$$ grid if $$|P| =t^2$$ , and $${\text {conv}}P$$ does not contain the intersection point of some two lines in $$\mathcal {L}_a$$ and does not contain the intersection point of some two lines in $$\mathcal {L}_b$$ . For fixed $$t > 1$$ , we show that any arrangement of n points and n lines in the plane that does not contain a natural $$t\times t$$ grid determines $$O(n^{{4}/{3}- \varepsilon })$$ incidences, where $$\varepsilon = \varepsilon (t)>0$$ . We also provide a construction of n points and n lines in the plane that does not contain a natural $$2 \times 2$$ grid and determines at least $$\Omega ({n^{1+{1}/{14}}})$$ incidences.
Maximum Causal Entropy Specification Inference from Demonstrations

In many settings, such as robotics, demonstrations provide a natural way to specify tasks. However, most methods for learning from demonstrations either do not provide guarantees that the learned artifacts can be safely composed or do not explicitly capture temporal properties. Motivated by this deficit, recent works have proposed learning Boolean task specifications, a class of Boolean non-Markovian rewards which admit well-defined composition and explicitly handle historical dependencies. This work continues this line of research by adapting maximum causal entropy inverse reinforcement learning to estimate the posteriori probability of a specification given a multi-set of demonstrations. The key algorithmic insight is to leverage the extensive literature and tooling on reduced ordered binary decision diagrams to efficiently encode a time unrolled Markov Decision Process. This enables transforming a naive algorithm with running time exponential in the episode length, into a polynomial time algorithm.
Direct label-free imaging of nanodomains in biomimetic and biological membranes by cryogenic electron microscopy.

The nanoscale organization of biological membranes into structurally and compositionally distinct lateral domains is believed to be central to membrane function. The nature of this organization has remained elusive due to a lack of methods to directly probe nanoscopic membrane features. We show here that cryogenic electron microscopy (cryo-EM) can be used to directly image coexisting nanoscopic domains in synthetic and bioderived membranes without extrinsic probes. Analyzing a series of single-component liposomes composed of synthetic lipids of varying chain lengths, we demonstrate that cryo-EM can distinguish bilayer thickness differences as small as 0.5 A, comparable to the resolution of small-angle scattering methods. Simulated images from computational models reveal that features in cryo-EM images result from a complex interplay between the atomic distribution normal to the plane of the bilayer and imaging parameters. Simulations of phase-separated bilayers were used to predict two sources of contrast between coexisting ordered and disordered phases within a single liposome, namely differences in membrane thickness and molecular density. We observe both sources of contrast in biomimetic membranes composed of saturated lipids, unsaturated lipids, and cholesterol. When extended to isolated mammalian plasma membranes, cryo-EM reveals similar nanoscale lateral heterogeneities. The methods reported here for direct, probe-free imaging of nanodomains in unperturbed membranes open new avenues for investigation of nanoscopic membrane organization.
Modeling return of the epidemic: Impact of population structure, asymptomatic infection, case importation and personal contacts.

Abstract Background Proactive interventions have halted the pandemic of coronavirus infected disease in some regions. However, without reaching herd immunity, the return of epidemic is possible. We investigate the impact of population structure, case importation, asymptomatic cases, and the number of contacts on a possible second wave of epidemic through mathematical modeling. Methods we built a modified Susceptible-exposed-Infectious-Removed (SEIR) model with parameters mirroring those of the COVID-19 pandemic and reported simulated characteristics of epidemics for incidence, hospitalizations and deaths under different scenarios. Results A larger percent of elderly people leads to higher number of hospitalizations, while a large percent of prior infection will effectively curb the epidemic. The number of imported cases and the speed of importation have small impact on the epidemic progression. However, a higher percent of asymptomatic cases slows the epidemic down and reduces the number of hospitalizations and deaths at the epidemic peak. Finally, reducing the number of contacts among young people alone has moderate effects on themselves, but little effects on the elderly population. However, reducing the number of contacts among elderly people alone can mitigate the epidemic significantly in both age groups, even though young people remain active within themselves. Conclusion Reducing the number of contacts among high risk populations alone can mitigate the burden of epidemic in the whole society. Interventions targeting high risk groups may be more effective in containing or mitigating the epidemic.
Reaching a Consensus on Random Networks: The Power of Few.

A community of $n$ individuals splits into two camps, Red and Blue. The individuals are connected by a social network, which influences their colors. Everyday, each person changes his/her color according to the majority among his/her neighbors. Red (Blue) wins if everyone in the community becomes Red (Blue) at some point. We study this process when the underlying network is the random Erdos-Renyi graph $G(n, p)$. With a balanced initial state ($n/2$ person in each camp), it is clear that each color wins with the same probability. Our study reveals that for any constants $p$ and $\varepsilon$, there is a constant $C$ such that if one camp has $n/2 +C$ individuals, then it wins with probability at least $1 - \varepsilon$. The surprising key fact here is that $C$ does not depend on $n$, the population of the community. When $p=1/2$ and $\varepsilon =.1$, one can set $C$ as small as 6. If the aim of the process is to choose a candidate, then this means it takes only $6$ "defectors" to win an election unanimously with overwhelming odd.
Patterns of palliative care consultation among patients with brain metastasis: an opportunity for radiation oncologists to facilitate earlier referral

Background Early palliative care (PC) physician involvement alongside standard oncologic care has been recommended by the American Society of Clinical Oncology (ASCO) guidelines for all advanced cancer patients, although adherence to these guidelines is variable. Radiation oncologists (ROs) could help facilitate early PC referral for patients treated with palliative radiation, particularly those with brain metastasis (BRM), and the aim of this study was to evaluate the circumstances of PC referral at our institution to better understand the multidisciplinary approaches to facilitate it. Methods Patients diagnosed with BRM from non-small cell lung cancer (NSCLC) from 2012 to 2018 whose primary RO and MO were at our institution were reviewed. Overall survival and time to PC consultation from the first oncologic visit following BRM diagnosis was determined using the KaplanMeier method. Mann-Whitney U and Chi-Squared assessed for predictive factors for shorter time to PC consultation. For these factors, the overall survival, rate of PC consultation, and PC setting was used to determine utilization of early PC. Results Among 103 eligible patients, only 48% underwent a PC consultation in their lifetime, with the initial evaluation being as an outpatient for 37%, and within 1 month of death for 35%. Median survival from BRM diagnosis was 9.0 months. The median time from oncologic appointment to PC referral was 2.8 months, and from initial PC consultation to death was 1.6 months. Only more recent BRM diagnosis (2016-2018 vs. 2012-2015) was associated with shorter time to PC consultation (1.0 vs. 5.6 months, P=0.013), increased PC consult rate (60% vs. 42%, P=0.105), and increased outpatient PC consultation (56% vs. 26%, P=0.037). Conclusions The majority of patients did not undergo early PC consultation, though utilization has improved over time. As ROs are commonly involved in BRM management, they may be in a position to proactively support early PC consultations in this patient population.
Image transmission across a magnetic chiral boundary under uniform and Gaussian-profile beams

Results obtained for Fresnel coefficients corresponding to a magnetic achiral/chiral interface under different incident angles and permittivity/permeability ratios, are extended to examine the transmitted amplitude profile of a 2D image/transparency. Both uniform and Gaussian- profile incident beams are considered.
Single-mode fiber-optic catheter/endoscope for optical coherence tomography

Summary form only given. In order to apply OCT for imaging of internal organ systems, a flexible, small diameter, catheter/endoscope, which is capable of delivering, focusing, scanning, and collecting a single-spatial-mode optical beam, must be constructed. In this summary, we describe the design and performance of a prototype single-mode fiber-optic scanning OCT catheter with a diameter of 1 mm. OCT imaging may be performed at 1.3-micron wavelengths using either a superluminescent laser diode source or a Kerr-lens mode-locked Cr:forsterite laser, which provides high powers for high-speed imaging. This device is an enabling technology for OCT and will permit micron scale, cross-sectional medical diagnostic imaging in tissues such as the vascular system, the gastrointestinal tract, the urinary tract, and the respiratory tract.
Autonomic Instability Secondary to Glomus Vagale Paraganglioma

Introduction Paragangliomas are rare vascular neuroendocrine tumors that arise from neural crest chromaffin cells that are associated with autonomic ganglion. A small subset of these tumors are found in the head and neck region and originate in the carotid and aortic bodies. Case description A 60-year-old woman presents with recurrent near syncopal episodes for 3 days associated with loss of appetite and 20-pound weight loss for 2 months. Two years ago, the patient presented with similar presyncopal episodes and Holter monitoring at that time showed multiple pauses up to 20 seconds, after which she was referred for dual chamber pacemaker implantation. During that time, a tilt table test and finometer measuring beat to beat blood pressure values was positive for sudden episodic hypotension and bradycardia every 2-3 minutes and were associated with lightheadedness and near syncope. Vitals during hospitalization showed BP ranging from 80s/50s to 130s/80s. Physical exam showed normal cardiopulmonary findings but revealed a right cervical mass along the angle of mandible, mildly tender to palpation. EKG showed an appropriately paced atrial rhythm at 59 beats per minute without any other abnormalities. As a result of her hypotensive episodes, the patient was started on fludrocortisone and pyridostigmine. CT neck with contrast showed a post styloid compartment mass with significant compression of R internal jugular vein and branches of R carotid artery. Subsequent angiography showed 4 × 3 × 3 cm. hypervascular mass in the upper right neck with displacement of carotid arteries and AV shunting into the R internal jugular vein. Findings were consistent with Glomus Vagale Paraganglioma and patient was discharged in stable condition for outpatient evaluation for surgical resection of mass. Discussion Indistinguishable from pheochromocytomas at the cellular level, paragangliomas are divided into catecholamine secreting sympathetic and nonfunctional parasympathetic neoplasms. Although most cases are sporadic, there is a link between paragangliomas and mutation of genes coding for Succinate Dehydrogenase (SDH) enzyme, Von Hippel Lindau, MEN2, and NF1 syndromes. Paragangliomas are usually asymptomatic and present as painless cervical masses. Glomus vagale, a particularly rare type of paraganglioma located near the vagus nerve, can present with tinnitus, dysphagia, or hoarseness. Carotid sinus compression by the cervical mass can lead to symptomatic hypotension and bradycardia, as seen in our case. The diagnosis of non-secretory paragangliomas includes 24-hour urine test to measure catecholamine and metanephrine levels and visualization of tumor via ultrasound, CT, or MRI which can show a “salt and pepper” appearance due to micro hemorrhage and hypervascularization. Treatment includes surgery, embolization, or radiotherapy. Conclusion Paragangliomas are uncommon tumors with glomus paragangliomas being a rare subtype. Because of their cellular composition and anatomic locations, they often cause autonomic instability. Further research should be performed to improve diagnosis and treatment.
Thermal Stress Analysis of Liquid-Cooled 3D-ICs

It is known that 3D-ICs suffer from hot spot temperatures that can reach thousands of degrees if they are not cooled to reasonable operating temperatures. The problem of hot spots is not limited to the high temperatures of the IC; thermal stress can also pose severe problems, even after cooling the chip. This study investigates thermal stress resulting from a 3D-IC hot spot with 20 W power dissipation. The IC is cooled using SiO 2 and diamond cooling blocks. The study is performed using three coolants: water, Freon (R22), and Liquid Nitrogen (LN). As expected, the study shows that metal layers on the chip suffer from high thermal stress due to rising of the chip temperature to values higher than the room temperature. It is also noticed that the stress becomes more severe if cooling is done using LN. In fact, the stress exceeded the maximum tensile strength of aluminum, which might cause failure of the chip. This indicates that cooling 3D-IC may not ensure acceptable operation or reliability. Thermal stress must be investigated at both high and low temperatures to ensure high performance and acceptable reliability.
Sources of predictive information in dynamical neural networks.

Behavior involves the ongoing interaction between an organism and its environment. One of the prevailing theories of adaptive behavior is that organisms are constantly making predictions about their future environmental stimuli. However, how they acquire that predictive information is still poorly understood. Two complementary mechanisms have been proposed: predictions are generated from an agent’s internal model of the world or predictions are extracted directly from the environmental stimulus. In this work, we demonstrate that predictive information, measured using bivariate mutual information, cannot distinguish between these two kinds of systems. Furthermore, we show that predictive information cannot distinguish between organisms that are adapted to their environments and random dynamical systems exposed to the same environment. To understand the role of predictive information in adaptive behavior, we need to be able to identify where it is generated. To do this, we decompose information transfer across the different components of the organism-environment system and track the flow of information in the system over time. To validate the proposed framework, we examined it on a set of computational models of idealized agent-environment systems. Analysis of the systems revealed three key insights. First, predictive information, when sourced from the environment, can be reflected in any agent irrespective of its ability to perform a task. Second, predictive information, when sourced from the nervous system, requires special dynamics acquired during the process of adapting to the environment. Third, the magnitude of predictive information in a system can be different for the same task if the environmental structure changes.
An electro-thermal computational study of conducting channels in dielectric thin films using self-consistent phase-field methodology: A view toward the physical origins of resistive switching

A large number of experimental studies suggest that two-terminal resistive switching devices made of a dielectric thin film sandwiched by a pair of electrodes exhibit reversible multi-state switching behaviors; however, coherent understanding of physical and chemical origins of their electrical properties needs to be further pursued to improve and customize the performance. In this paper, phase-field methodology is used to study the formation and annihilation of conductive channels, resulting in reversible resistive switching behaviors that can generally occur in any dielectric thin films. Our focus is on the dynamical evolution of domains made of electrical charges under the influence of a spatially varying electric field and a temperature, resulting in distinctive changes in electrical conductance.
Dynamical Systems Theory and Algorithms for NP-hard Problems

This article surveys the burgeoning area at the intersection of dynamical systems theory and algorithms for NP-hard problems. Traditionally, computational complexity and the analysis of non-deterministic polynomial-time (NP)-hard problems have fallen under the purview of computer science and discrete optimization. However, over the past few years, dynamical systems theory has increasingly been used to construct new algorithms and shed light on the hardness of problem instances. We survey a range of examples that illustrate the use of dynamical systems theory in the context of computational complexity analysis and novel algorithm construction. In particular, we summarize a) a novel approach for clustering graphs using the wave equation partial differential equation, b) invariant manifold computations for the traveling salesman problem, c) novel approaches for building quantum networks of Duffing oscillators to solve the MAX-CUT problem, d) applications of the Koopman operator for analyzing optimization algorithms, and e) the use of dynamical systems theory to analyze computational complexity.
Adam Smith and Economic Development in Theory and Practice: A Rejection of Stadial Model?

Adam Smith allegedly offers a model of economic development both in his Lectures on Jurisprudence and in the Wealth of Nations — the so called four stages of development model. The model presents a linear unfolding view of economic development from primitive to advanced stages. But Smith´s own historical examples systematically contradict this model. I thus question whether Adam Smith actually endorses and uses the four stages model of development to illustrate development and suggest that if he does, he does it to discredit it instead. For Smith history teaches that development is more accidental than fitting deterministic models.
Disentangling the Generalized Double Semion Model

We analyze the class of Generalized Double Semion (GDS) models in arbitrary dimensions from the point of view of lattice Hamiltonians. We show that on a d-dimensional spatial manifold M the dual of the GDS is equivalent, up to constant depth local quantum circuits, to a group cohomology theory tensored with lower dimensional cohomology models that depend on the manifold M. We comment on the space-time topological quantum field theory (TQFT) interpretation of this result. We also investigate the GDS in the presence of time reversal symmetry, showing that it forms a non-trivial symmetry enriched toric code phase in odd spatial dimensions.
Exploring the top and bottom of the quantum control landscape.

A controlled quantum system possesses a search landscape defined by the target physical objective as a function of the controls. This paper focuses on the landscape for the transition probability Pi → f between the states of a finite level quantum system. Traditionally, the controls are applied fields; here, we extend the notion of control to also include the Hamiltonian structure, in the form of time independent matrix elements. Level sets of controls that produce the same transition probability value are shown to exist at the bottom Pi → f = 0.0 and top Pi → f = 1.0 of the landscape with the field and/or Hamiltonian structure as controls. We present an algorithm to continuously explore these level sets starting from an initial point residing at either extreme value of Pi → f. The technique can also identify control solutions that exhibit the desirable properties of (a) robustness at the top and (b) the ability to rapidly rise towards an optimal control from the bottom. Numerical simulations are presented to illustrate the varied control behavior at the top and bottom of the landscape for several simple model systems.
Formation and Properties of Astrophysical Carbonaceous Dust. I. Ab-initio Calculations of the Configuration and Binding Energies of Small Carbon Clusters

The binding energies of n < 100 carbon clusters are calculated using the ab initio density functional theory code Quantum Espresso. Carbon cluster geometries are determined using several levels of classical techniques and further refined using density functional theory. The resulting energies are used to compute the work of cluster formation and the nucleation rate in a saturated, hydrogen-poor carbon gas. Compared to classical calculations that adopt the capillary approximation, we find that nucleation of carbon clusters is enhanced at low temperatures and depressed at high temperatures. This difference is ascribed to the different behavior of the critical cluster size. We find that the critical cluster size is at n = 27 or n = 8 for a broad range of temperatures and saturations, instead of being a smooth function of such parameters. The results of our calculations can be used to follow carbonaceous cluster/grain formation, stability, and growth in hydrogen-poor environments, such as the inner layers of core-collapse supernovae and supernova remnants.
AN HST SURVEY OF THE HIGHEST-VELOCITY EJECTA IN CASSIOPEIA A*

We present Hubble Space Telescope WFC3/IR images of the Cassiopeia A supernova remnant that survey its high-velocity, S-rich debris in the NE jet and SW counterjet regions through [S III] 9069, 9531 and [S II] 10,287 - 10,370 line emissions. We identify nearly 3400 sulfur emitting knots concentrated in ~120 degree wide opposing streams, almost triple the number previously known. The vast majority of these ejecta knots lie at projected distances well out ahead of the remnant's forward blast wave and main shell ejecta, extending to angular distance of 320" to the NE and 260" to the SW from the center of expansion. Such angular distances imply undecelerated ejecta knot transverse velocities of 15,600 and 12,700 km/s respectively, assuming an explosion date ~1670 AD and a distance of 3.4 kpc. Optical spectra of knots near the outermost tip of the NE ejecta stream show strong emission lines of S, Ca, and Ar. We estimate a total mass ~0.1 Msun and a kinetic energy of at least ~1 x10^50 erg for S-rich ejecta in the NE jet and SW counterjet. Although their broadness and kinetic energy argue against the Cas~A SN being a jet-induced explosion, the jets are kinematically and chemically distinct from the rest of the remnant. This may reflect an origin in a jet-like mechanism that accelerated interior material from a Si,S,Ar,Ca-rich region near the progenitor's core up through the mantle and H,He,N and O-rich outer layers with velocities that greatly exceeded that of the rapidly expanding photosphere.
Centimeter Searches for Molecular Line Emission from High-Redshift Galaxies

We consider the capabilities for detecting low-order CO emission lines from high-redshift (z) galaxies using the next generation of radio telescopes operating at 22 and 43 GHz. Low-order CO emission studies provide critical insight into the nature of high-redshift galaxies, including (1) determining gas masses, (2) study of large-scale structure through three-dimensional redshift surveys over cosmologically relevant volumes, (3) imaging gas kinematics on kiloparsec scales, and, in conjunction with observations of higher order transitions using future millimeter telescopes, (4) constraining the excitation conditions of the gas. Particular attention is paid to the impact on such studies of the high-frequency limit for future centimeter telescopes. We employ models for the evolution of dusty star-forming galaxies based on source counts at (sub)millimeter wavelengths and on the observed millimeter through infrared backgrounds, to predict the expected detection rate of low-order CO (2-1) and CO (1-0) line-emitting galaxies for optimal centimeter-wave surveys using future radio telescopes, such as the Square Kilometer Array (SKA) and the Expanded Very Large Array (EVLA). We then compare these results to surveys that can be performed with the next-generation millimeter-wave telescope, the Atacama Large Millimeter Array (ALMA). Operating at 22 GHz, the SKA will be competitive with the ALMA in terms of the detection rate of lines from high-z galaxies and will be potentially superior by an order of magnitude if extended to 43 GHz. Perhaps more importantly, centimeter-wave telescopes are sensitive to lower excitation gas in higher redshift galaxies and so provide a complementary view of conditions in high-redshift galaxies to millimeter-wave surveys. We have also included in our models emission from HCN. The number of HCN (1-0) detections will be about 5% of the CO detections in the (CO-optimized) 22 GHz surveys and about 1.5% for 43 GHz surveys. In order not to overresolve the sources, brightness temperature limitations require that future large-area centimeter telescopes have much of their collecting area on baselines shorter than 10 km.
Hecke relations in rational conformal field theory

We define Hecke operators on vector-valued modular forms of the type that appear as characters of rational conformal field theories (RCFTs). These operators extend the previously studied Galois symmetry of the modular representation and fusion algebra of RCFTs to a relation between RCFT characters. We apply our results to derive a number of relations between characters of known RCFTs with different central charges and also explore the relation between Hecke operators and RCFT characters as solutions to modular linear differential equations. We show that Hecke operators can be used to construct an infinite set of possible characters for RCFTs with two independent characters and increasing central charge. These characters have multiplicity one for the vacuum representation, positive integer coefficients in their q expansions, and are associated to a two-dimensional representation of the modular group which leads to non-negative integer fusion coefficients as determined by the Verlinde formula.
Undulatory swimming in fluids with polymer networks

The motility behavior of the nematode Caenorhabditis elegans in polymeric solutions of varying concentrations is systematically investigated in experiments using tracking and velocimetry methods. As the polymer concentration is increased, the solution undergoes a transition from the semi-dilute to the concentrated regime, where these rod-like polymers entangle, align, and form networks. Remarkably, we find an enhancement in the nematode's swimming speed of approximately 65% in concentrated solutions compared to semi-dilute solutions. Using velocimetry methods, we show that the undulatory swimming motion of the nematode induces an anisotropic mechanical response in the fluid. This anisotropy, which arises from the fluid micro-structure, is responsible for the observed increase in swimming speed.
Microscopic theory of non-adiabatic response in real and imaginary time

We present a general approach to describe slowly driven quantum systems both in real and imaginary time. We highlight many similarities, qualitative and quantitative, between real and imaginary time evolution. We discuss how the metric tensor and the Berry curvature can be extracted from both real and imaginary time simulations as a response of physical observables. For quenches ending at or near the quantum critical point, we show the utility of the scaling theory for detecting the location of the quantum critical point by comparing sweeps at different velocities. We briefly discuss the universal relaxation to equilibrium of systems after a quench. We finally review recent developments of quantum Monte Carlo methods for studying imaginary time evolution. We illustrate our findings with explicit calculations using the transverse-field Ising model in one dimension.
PBMap: A Path Balancing Technology Mapping Algorithm for Single Flux Quantum Logic Circuits

This paper presents a path balancing technology mapping algorithm, which is a new algorithm for generating a mapping solution for a given Boolean network such that the average logic level difference among fanin gates of each gate in the network is minimized. Path balancing technology mapping is required in dc-biased single flux quantum (SFQ) circuits for guaranteeing the correct operation, and it is beneficial in CMOS circuits to reduce the hazard issues. We present a dynamic programming based algorithm for path balancing technology mapping, which generates optimal solutions for dc-biased SFQ (e.g., rapid SFQ or RSFQ) circuits with tree structure and acts as an effective heuristic for circuits with general directed acyclic graph structure. Experimental results show that our path balancing technology mapper reduces the balancing overhead by up to 2.7 × and with an average of 21% compared to the state-of-the-art academic technology mappers.
Selection for Decreased BRCA2 Functional Activity in Homo sapiens After Divergence from the Chimpanzee-Human Last Common Ancestor

Abstract Humans have an increased incidence of epithelial neoplasia compared to non-human primates. We performed a comparative analysis of 21 non-human primate genomes and 54 ancient human genomes to identify variations in known cancer genes that may explain this difference. We identified 299 human-specific fixed non-silent single nucleotide polymorphisms. Bioinformatics analyses for functional consequences identified a number of variants predicted to have altered protein function, one of which was located at the most evolutionarily conserved domain of human BRCA2. This variant, in which a polar threonine residue replaces a hydrophobic methionine residue to codon 2662 within the DSS1 binding domain, decreases the interactions of BRCA2 with other proteins, specifically the binding of BRCA2 and RAD51, as well as the repairing ability of cells for DNA double-strand breaks. We conclude that a 20% reduction in BRCA2 DNA repair ability was positively selected for in the course of human evolution. One Sentence Summary Reduction of BRCA2 functional activity has been selected for during human evolution since the chimpanzee-human last common ancestor.
Factors Influencing the Surprising Instability of Word Embeddings

Despite the recent popularity of word embedding methods, there is only a small body of work exploring the limitations of these representations. In this paper, we consider one aspect of embedding spaces, namely their stability. We show that even relatively high frequency words (100-200 occurrences) are often unstable. We provide empirical evidence for how various factors contribute to the stability of word embeddings, and we analyze the effects of stability on downstream tasks.
Precise Doppler Monitoring of Barnard's Star

We present 248 precise Doppler measurements of Barnard's Star (Gl 699), the second nearest star system to Earth, obtained from Lick and Keck Observatories during the 25 years between 1987 and 2012. The early precision was 20 m s^(–1) but was 2 m s^(–1) during the last 8 years, constituting the most extensive and sensitive search for Doppler signatures of planets around this stellar neighbor. We carefully analyze the 136 Keck radial velocities spanning 8 years by first applying a periodogram analysis to search for nearly circular orbits. We find no significant periodic Doppler signals with amplitudes above ~2 m s^(–1), setting firm upper limits on the minimum mass (M sin i) of any planets with orbital periods from 0.1 to 1000 days. Using a Monte Carlo analysis for circular orbits, we determine that planetary companions to Barnard's Star with masses above 2 M_⊕ and periods below 10 days would have been detected. Planets with periods up to 2 years and masses above 10 M_⊕ (0.03 M_(Jup)) are also ruled out. A similar analysis allowing for eccentric orbits yields comparable mass limits. The habitable zone of Barnard's Star appears to be devoid of roughly Earth-mass planets or larger, save for face-on orbits. Previous claims of planets around the star by van de Kamp are strongly refuted. The radial velocity of Barnard's Star increases with time at 4.515 ± 0.002 m s^(–1) yr^(–1), consistent with the predicted geometrical effect, secular acceleration, that exchanges transverse for radial components of velocity.
Reconstructing function fields from rational quotients of mod-\ell Galois groups

In this paper, we develop the main step in the global theory for the mod-\(\ell \) analogue of Bogomolov’s program in birational anabelian geometry for higher-dimensional function fields over algebraically closed fields. More precisely, we show how to reconstruct a function field K of transcendence degree \(\ge \)5 over an algebraically closed field, up-to inseparable extensions, from the mod-\(\ell \) abelian-by-central Galois group of K endowed with the collection of mod-\(\ell \) rational quotients.
Variable selection in nonparametric additive models

We consider a nonparametric additive model of a conditional mean function in which the number of variables and additive components may be larger than the sample size but the number of nonzero additive components is "small" relative to the sample size. The statistical problem is to determine which additive components are nonzero. The additive components are approximated by truncated series expansions with B-spline bases. With this approximation, the problem of component selection becomes that of selecting the groups of coefficients in the expansion. We apply the adaptive group Lasso to select nonzero components, using the group Lasso to obtain an initial estimator and reduce the dimension of the problem. We give conditions under which the group Lasso selects a model whose number of components is comparable with the underlying model, and the adaptive group Lasso selects the nonzero components correctly with probability approaching one as the sample size increases and achieves the optimal rate of convergence. The results of Monte Carlo experiments show that the adaptive group Lasso procedure works well with samples of moderate size. A data example is used to illustrate the application of the proposed method.
Extragalactic HI surveys

We review the results of HI line surveys of extragalactic sources in the local Universe. In the last two decades major efforts have been made in establishing on firm statistical grounds the properties of the HI source population, the two most prominent being the HI Parkes All Sky Survey and the Arecibo Legacy Fast ALFA survey. We review the choices of technical parameters in the design and optimization of spectro-photometric “blind” HI surveys, which for the first time produced extensive HI-selected data sets. Particular attention is given to the relationship between optical and HI populations, the differences in their clustering properties and the importance of HI-selected samples in contributing to the understanding of apparent conflicts between observation and theory on the abundance of low mass halos. The last section of this paper provides an overview of currently ongoing and planned surveys which will explore the cosmic evolution of properties of the HI population.
Wavefield reconstruction inversion: an example

Nonlinear least squares data-fitting driven by physical process simulation is a classic and widely successful technique for the solution of inverse problems in science and engineering. Known as "Full Waveform Inversion" in application to seismology, it can extract detailed maps of earth structure from near-surface seismic observations, but also suffers from a defect not always encountered in other applications: the least squares error function at the heart of this method tends to develop a high degree of nonconvexity, so that local optimization methods (the only numerical methods feasible for field-scale problems) may fail to produce geophysically useful final estimates of earth structure, unless provided with initial estimates of a quality not always available. A number of alternative optimization principles have been advanced that promise some degree of release from the multimodality of Full Waveform Inversion, amongst them Wavefield Reconstruction Inversion, the focus of this paper. Applied to a simple 1D acoustic transmission problem, both Full Waveform and Wavefield Reconstruction Inversion methods reduce to minimization of explicitly computable functions, in an asymptotic sense. The analysis presented here shows explicitly how multiple local minima arise in Full Waveform Inversion, and that Wavefield Reconstruction Inversion can be vulnerable to the same "cycle-skipping" failure mode.
Theoretical Justification and Error Analysis for Slender Body Theory with Free Ends

Slender body theory is a commonly used approximation in computational models of thin fibers in viscous fluids, especially in simulating the motion of cilia or flagella in swimming microorganisms. In Mori et al. (Commun Pure Appl Math, 2018. arXiv:1807.00178), we developed a PDE framework for analyzing the error introduced by the slender body approximation for closed-loop fibers with constant radius $$\varepsilon $$, and showed that the difference between our closed-loop PDE solution and the slender body approximation is bounded by an expression proportional to $$\varepsilon |\log \varepsilon |$$. Here we extend the slender body PDE framework to the free endpoint setting, which is more physically relevant from a modeling standpoint but more technically demanding than the closed loop analysis. The main new difficulties arising in the free endpoint setting are defining the endpoint geometry, identifying the extent of the 1D slender body force density, and determining how the well-posedness constants depend on the non-constant fiber radius. Given a slender fiber satisfying certain geometric constraints at the filament endpoints and a one-dimensional force density satisfying an endpoint decay condition, we show a bound for the difference between the solution to the slender body PDE and the slender body approximation in the free endpoint setting. The bound is a sum of the same $$\varepsilon |\log \varepsilon |$$ term appearing in the closed loop setting and an endpoint term proportional to $$\varepsilon $$, where $$\varepsilon $$ is now the maximum fiber radius.
Jordan-Wigner dualities for translation-invariant Hamiltonians in any dimension: Emergent fermions in fracton topological order

The author generalizes the Jordan-Wigner Transformation to any translation-invariant fermion system, including cases where fermion parity is conserved on individual subdimensional manifolds, such as planes or fractals. The paper finds that in three dimensions, the dual spin model is an exotic gauge theory where point-like excitations have fundamentally restricted mobility called fractons, yet simultaneously are emergent fermions.
Augmented L1 and Nuclear-Norm Models with a Globally Linearly Convergent Algorithm

This paper studies the long-existing idea of adding a nice smooth function to “smooth” a nondifferentiable objective function in the context of sparse optimization, in particular, the minimization of $\|\mathbf{x}\|_1+\frac{1}{2\alpha}\|\mathbf{x}\|_2^2$, where $\mathbf{x}$ is a vector, as well as the minimization of $\|\mathbf{X}\|_*+\frac{1}{2\alpha}\|\mathbf{X}\|_F^2$, where $\mathbf{X}$ is a matrix and $\|\mathbf{X}\|_*$ and $\|\mathbf{X}\|_F$ are the nuclear and Frobenius norms of $\mathbf{X}$, respectively. We show that they let sparse vectors and low-rank matrices be efficiently recovered. In particular, they enjoy exact and stable recovery guarantees similar to those known for the minimization of $\|\mathbf{x}\|_1$ and $\|\mathbf{X}\|_*$ under the conditions on the sensing operator such as its null-space property, restricted isometry property (RIP), spherical section property, or “RIPless” property. To recover a (nearly) sparse vector $\mathbf{x}^0$, minimizing $\|\mathbf{x}\|_1+\frac{1}{2\alpha}\...
When Can Dictionary Learning Uniquely Recover Sparse Data From Subsamples

Sparse coding or sparse dictionary learning has been widely used to recover underlying structure in many kinds of natural data. Here, we provide conditions guaranteeing when this recovery is universal; that is, when sparse codes and dictionaries are unique (up to natural symmetries). Our main tool is a useful lemma in combinatorial matrix theory that allows us to derive bounds on the sample sizes guaranteeing such uniqueness under various assumptions for how training data are generated. Whenever the conditions to one of our theorems are met, any sparsity-constrained learning algorithm that succeeds in reconstructing the data recovers the original sparse codes and dictionary. We also discuss potential applications to neuroscience and data analysis.
The Haldane-Rezayi quantum Hall state and conformal field theory

We propose field theories for the bulk and edge of a quantum Hall state in the universality class of the Haldane-Rezayi wavefunction. The bulk theory is associated with the c = −2 conformal field theory. The topological properties of the state, such as the quasiparticle braiding statistics and ground state degeneracy on a torus, may be deduced from this conformal field theory. The 10-fold degeneracy on a torus is explained by the existence of a logarithmic operator in the c = −2 theory; this operator corresponds to a novel bulk excitation in the quantum Hall state. We argue that the edge theory is the c = 1 chiral Dirac fermion, which is related in a simple way to the c = −2 theory of the bulk. This theory is reformulated as a truncated version of a doublet of Dirac fermions in which the SU(2) symmetry - which corresponds to the spin-rotational symmetry of the quantum Hall system - is manifest and non-local. We make predictions for the current-voltage characteristics for transport through point contacts.
A Disk-wind Model for the Near-infrared Excess Emission in Protostars

Protostellar systems, ranging from low-luminosity classical T Tauri and Herbig Ae stars to high-luminosity Herbig Be stars, exhibit a near-infrared (NIR) excess in their spectra that is dominated by a bump in the monochromatic luminosity with a peak near 3 {mu}m. The bump can be approximated by a thermal emission component of temperature {approx}1500 K that is of the order of the sublimation temperature of interstellar dust grains. In the currently popular 'puffed-up rim' scenario, the bump represents stellar radiation that propagates through the optically thin inner region of the surrounding accretion disk and is absorbed and reemitted by the dust that resides just beyond the dust sublimation radius r {sub sub}. However, this model cannot account for the strongest bumps measured in these sources, and it predicts a pronounced secondary bounce in the interferometric visibility curve that is not observed. In this paper we present an alternative interpretation, which attributes the bump to reemission of stellar radiation by dust that is uplifted from the disk by a centrifugally driven wind. Winds of this type are a leading candidate for the origin of the strong outflows associated with protostars, and there is observational evidence for disk winds originating on scalesmore » {approx}r {sub sub}. Using a newly constructed Monte Carlo radiative transfer code and focusing on low-luminosity sources, we show that this model can account for the NIR excess emission even in bright Herbig Ae stars such as AB Auriga and MWC 275, and that it successfully reproduces the basic features of the visibilities measured in these protostars. We argue that a robust dusty outflow in these sources could be self-limiting-through shielding of the stellar FUV photons-to a relatively narrow launching region between r {sub sub} and {approx}2 r {sub sub}. We also suggest that the NIR and scattered-light variability exhibited by a source like MWC 275 can be attributed in this picture to the uplifting of dust clouds from the disk.« less