cssi/SciSciGPT-SciSciNet huggingface dataset:
Reeb Graphs: Approximation and Persistence

Given a continuous function f:X→ℝ on a topological space X, its level set f −1(a) changes continuously as the real value a changes. Consequently, the connected components in the level sets appear, disappear, split and merge. The Reeb graph of f summarizes this information into a graph structure. Previous work on Reeb graph mainly focused on its efficient computation. In this paper, we initiate the study of two important aspects of the Reeb graph, which can facilitate its broader applications in shape and data analysis. The first one is the approximation of the Reeb graph of a function on a smooth compact manifold M without boundary. The approximation is computed from a set of points P sampled from M. By leveraging a relation between the Reeb graph and the so-called vertical homology group, as well as between cycles in M and in a Rips complex constructed from P, we compute the H 1-homology of the Reeb graph from P. It takes O(nlogn) expected time, where n is the size of the 2-skeleton of the Rips complex. As a by-product, when M is an orientable 2-manifold, we also obtain an efficient near-linear time (expected) algorithm for computing the rank of H 1(M) from point data. The best-known previous algorithm for this problem takes O(n 3) time for point data. The second aspect concerns the definition and computation of the persistent Reeb graph homology for a sequence of Reeb graphs defined on a filtered space. For a piecewise-linear function defined on a filtration of a simplicial complex K, our algorithm computes all persistent H 1-homology for the Reeb graphs in $O(n n_{e}^{3})$ time, where n is the size of the 2-skeleton and n e is the number of edges in K.
A nonlinear approach to interference alignment

Cadambe and Jafar (CJ) alignment strategy for the K-user scalar frequency-selective fading Gaussian channel, with encoding over blocks of 2n+1 random channel coefficients (subcarriers) is considered. The linear zero-forcing (LZF) strategy is compared with a novel approach based on lattice alignment and lattice decoding (LD). Despite both LZF and LD achieve the same degrees of freedom, it is shown that LD can achieve very significant improvements in terms of error rates at practical SNRs with respect to the conventional LZF proposed in the literature. We also show that these gains are realized provided that channel gains are controlled to be near constant, for example, by means of power control and opportunistic carrier and user selection strategies. In presence of relatively-small variations in the normalized channel coefficient amplitudes, CJ alignment strategy yields very disappointing results at finite SNRs, and the gain of LD over ZLF significantly reduces. In light of these results, the practical applicability of CJ alignment scheme remains questionable, in particular for Rayleigh fading channels, where channel inversion power control yields to unbounded average transmit power.
Differential associations of early callous‐unemotional, oppositional, and ADHD behaviors: multiple domains within early‐starting conduct problems?

Background: Early-starting child conduct problems (CP) are linked to the development of persistent antisocial behavior. Researchers have theorized multiple pathways to CP and that CP comprise separable domains, marked by callous-unemotional (CU) behavior, oppositional behavior, or ADHD symptoms. However, a lack of empirical evidence exists from studies that have examined whether there are unique correlates of these domains. Methods: We examined differential correlates of CU, oppositional, and ADHD behaviors during the preschool years to test their potentially distinct nomological networks. Multimethod data, including parent and teacher reports and observations of child behavior, were drawn from a prospective, longitudinal study of children assessed at age 3 and age 6 ( N= 240; 48% female). Results: Dimensions of CU, oppositional, and ADHD behaviors were separable within Confirmatory Factor Analyses across mother and father reports. There were differential associations between CU, oppositional, and ADHD behaviors and socioemotional, cognitive, and behavioral outcomes: CU behavior was uniquely related to lower moral regulation, guilt, and empathy. ADHD was uniquely related to lower attentional focusing and observed effortful control. Finally, CU behavior uniquely predicted increases in teacher-reported externalizing from ages 3–6 over and above covariates, and ADHD and oppositional behavior. Conclusions: Consistent with theory, dimensions of CU, ADHD, and oppositional behavior demonstrated separable nomological networks representing separable facets within early-starting CP. Keywords: Callous-unemotional, conduct problems, oppositional, attention deficit/ hyperactive, nomological network.
Quasi-randomness of graph balanced cut properties

Quasi-random graphs can be informally described as graphs whose edge distribution closely resembles that of a truly random graph of the same edge density. Recently, Shapira and Yuster proved the following result on quasi-randomness of graphs. Let k ≥ 2 be a fixed integer, α1,…,αk be positive reals satisfying \documentclass{article}\usepackage{mathrsfs}\usepackage{amsmath, amssymb}\pagestyle{empty}\begin{document} \begin{align*}\sum_{i} \alpha_i = 1\end{align*} \end{document} and (α1,…,αk)≠(1/k,…,1/k), and G be a graph on n vertices. If for every partition of the vertices of G into sets V 1,…,V k of size α1n,…,αkn, the number of complete graphs on k vertices which have exactly one vertex in each of these sets is similar to what we would expect in a random graph, then the graph is quasi-random. However, the method of quasi-random hypergraphs they used did not provide enough information to resolve the case (1/k,…,1/k) for graphs. In their work, Shapira and Yuster asked whether this case also forces the graph to be quasi-random. Janson also posed the same question in his study of quasi-randomness under the framework of graph limits. In this paper, we positively answer their question. © 2011 Wiley Periodicals, Inc. Random Struct. Alg., 2011, © 2012 Wiley Periodicals, Inc. (Supported by Samsung Scholarship.)
Stereochemical control in the reduction of 2-Chromanols

Reduction of C5-substituted 2-hydroxychromans selectively provides 2,4-cis-chromans using large silane reductants and 2,4-trans-chromans using the smaller silane PhSiH3. The stereochemical outcome has been rationalized on the basis of a Curtin−Hammett kinetic situation arising from hydride delivery to two different conformations of an intermediate oxocarbenium ion. This method provides a powerful way to control the relative stereochemistry of these substructures which are prevalent in bioactive natural products.
No such thing as failure, only feedback: Designing innovative opportunities for e-assessment and technology-mediated feedback

in this paper we challenge designers, researchers, teachers, students, and parents to re-assess and re-envision the value of technology-mediated feedback and e-assessment by examin ing the innovative roles feedback and assessment played in the design of three contemporary web-based learning envi ronments. These environments include 1) an e-assessment system for postsecondary american sign language learners, 2) a hybrid environment for teaching geography through the use of geospatial technologies, and 3) a progress-monitoring environment for reading, writing, and language development with deaf or hard-of-hearing students. For each design we share a brief overview of the instructional problem, audience, and initial design challenge, followed by a description of the specific feedback and assessment design opportunities. We conclude with suggestions to consider when designing future opportunities for online feedback and assessment.
An approach to robust decision making under severe uncertainty in life cycle design

Information-Gap Decision Theory (IGDT), an approach to robust decision making under severe uncertainty, is newly considered in the context of environmental performance affected by life cycle uncertainty. An IGDT decision strategy favours the design(s) that can endure the most estimation error while still guaranteeing no worse than some 'good enough' critical level of performance. In this paper, a simple automotive oil filter design selection example with severe uncertainty is formulated and solved using an IGDT approach. Implications of IGDT to life cycle engineering design problems are discussed, as are potential limitations that could be encountered when solving more complex problems.
The epidemiology of traumatic injury-related fetal mortality in Pennsylvania, 1995-1997: the role of motor vehicle crashes.

Methods: Rates and causes of traumatic injury-related fetal deaths in Pennsylvania were determined from a manual review of all fetal death certificates filed from 1995 to 1997 (7131 cases). Results: Thirty one traumatic injury cases were identified (6.5/100 000 live births). Most cases (94%) could be identified from the diagnosis code of 760.5 (maternal injury) and 87% contained narratives indicating specific injury mechanisms. Motor vehicles were the leading cause of injury (81%). Placental separation was the leading diagnosis (42%). Conclusions: The ICD-9-CM code 760.5 appears to be a specific indicator of traumatic fetal death, though it is not known how sensitive an indicator it is. Though not usually E-coded, the death certificates contained enough information to allow ascertainment of injury mechanism. These are very conservative estimates of the burden of the problem. The major role that motor vehicle injuries have on reported traumatic fetal injury deaths was shown and a significant new challenge for child passenger safety advocates is indicated.
Between 2- and 3-Colorability

We consider the question of the existence of homomorphisms between $G_{n,p}$ and odd cycles when $p=c/n$, $1<c\leq 4$. We show that for any positive integer $\ell$, there exists $\epsilon=\epsilon(\ell)$ such that if $c=1+\epsilon$ then w.h.p. $G_{n,p}$ has a homomorphism from $G_{n,p}$ to $C_{2\ell+1}$ so long as its odd-girth is at least $2\ell+1$. On the other hand, we show that if $c=4$ then w.h.p. there is no homomorphism from $G_{n,p}$ to $C_5$. Note that in our range of interest, $\chi(G_{n,p})=3$ w.h.p., implying that there is a homomorphism from $G_{n,p}$ to $C_3$. These results imply the existence of random graphs with circular chromatic numbers $\chi_c$ satisfying $2<\chi_c(G)<2+\delta$ for arbitrarily small $\delta$, and also that $2.5\leq \chi_c(G_{n,\frac 4 n})<3$ w.h.p.
Measuring the Consequences of Delegate Selection Rules in Presidential Nominations

In this paper, we formalize existing normative criteria used to judge presidential selection contests by modeling the translation of citizen votes in primaries and caucuses into delegates to the national party conventions. We use a statistical model that enables us to separate the form of electoral responsiveness in presidential selection systems, as well as the degree of bias toward each of the candidates. We find that (1) the Republican nomination system is more responsive to changes in citizen votes than the Democratic system; (2) non-PR primaries are always more responsive than PR primaries; (3) surprisingly, caucuses are more proportional than even primaries held under PR rules; (4) significant bias in favor of a candidate was a good prediction of the winner of the nomination contest. We also (5) evaluate the claims of Ronald Reagan in 1976 and Jesse Jackson in 1988 that the selection systems were substantially biased against their candidates. We find no evidence to support Reagan's claim, but substa...
An X-Ray Jet from a White Dwarf: Detection of the Collimated Outflow from CH Cygni with Chandra

Most symbiotic stars consist of a white dwarf accreting material from the wind of a red giant. An increasing number of these objects have been found to produce jets. Analysis of archival Chandra data of the symbiotic system CH Cygni reveals faint extended emission to the south, aligned with the optical and radio jets seen in earlier Hubble Space Telescope and Very Large Array observations. CH Cygni thus contains only the second known white dwarf with an X-ray jet, after R Aquarii. The X-rays from symbiotic star jets appear to be produced when jet material is shock-heated following collision with the surrounding gas, as with the outflows from some protostellar objects and bipolar planetary nebulae.
Mixed Signals: Market Incentives, Recycling and the Price Spike of 1995

Abstract Environmental economics assumes that reliance on price signals, adjusted for externalities, normally leads to efficient solutions to environmental problems. We explore a limiting case, when market volatility created ‘mixed signals’: prices of waste paper and other recycled materials were suddenly extremely high in 1994–1995, then plummeted back to traditional low levels in 1996. These rapid reversals resulted in substantial economic and political costs. A review of academic and business literature suggests six possible explanations for abrupt price spikes. An econometric analysis of the prices of wood pulp and waste paper shows that factor which explained price changes in 1983–1993 contribute very little to understanding the subsequent price spike. From the econometric analysis and from other sources, we conclude that speculation must have played a major role in the price spike, perhaps in combination with modest effects from changes in government policy and in export demand. If speculatively driven price spikes can disrupt an environmentally important industry such as recycling, what is the appropriate role for public policy? When price volatility is sufficiently disruptive, then measures to control or stabilize prices, rather than interfering with the market, might help to make it more efficient.
On Multiple Decoding Attempts for Reed–Solomon Codes: A Rate-Distortion Approach

One popular approach to soft-decision decoding of Reed-Solomon (RS) codes is based on using multiple trials of a simple RS decoding algorithm in combination with erasing or flipping a set of symbols or bits in each trial. This paper presents a framework based on rate-distortion (RD) theory to analyze these multiple-decoding algorithms. By defining an appropriate distortion measure between an error pattern and an erasure pattern, the successful decoding condition, for a single errors-and-erasures decoding trial, becomes equivalent to distortion being less than a fixed threshold. Finding the best set of erasure patterns also turns into a covering problem that can be solved asymptotically by RD theory. Thus, the proposed approach can be used to understand the asymptotic performance-versus-complexity tradeoff of multiple errors-and-erasures decoding of RS codes. This initial result is also extended a few directions. The rate-distortion exponent (RDE) is computed to give more precise results for moderate blocklengths. Multiple trials of algebraic soft-decision (ASD) decoding are analyzed using this framework. Analytical and numerical computations of the RD and RDE functions are also presented. Finally, simulation results show that sets of erasure patterns designed using the proposed methods outperform other algorithms with the same number of decoding trials.
The initial and potential impact of preferential access to the U.S. market under the African Growth and Opportunity Act

The ability to export clothing products under preferences with liberal rules of origin is the key factor currently determining whether the African Growth and Opportunity Act (AGOA) has a significant impact on non-oil exporting African countries. At present only a small number of countries receive substantial benefits and Least Developed Countries (LDCs) that do not receive preferences for clothing have yet to see an impact of AGOA on their overall exports. However, the benefits from exporting clothing under AGOA appear fragile in the face of the removal of quotas in the United States on major suppliers, such as China, at the end of 2004, and the planned removal of the liberal rules of origin that allow for the global sourcing of fabrics from least-cost locations. To entrench and enhance the benefits of AGOA, it is important that the scheme be extended over a much longer period, if not made permanent, and the special liberal rules of origin for clothing products be extended considerably beyond 2004. The effective inclusion of textile products and a number of high-duty agricultural products would also help to broaden the range of opportunities for African exporters in the U.S. market. Nevertheless it is important that the opportunities created by AGOA are integrated into a broader framework for promoting trade and that it be recognized that if the opportunities offered by more open trade are to be exploited there must be concerted efforts to improve the environment for investment in countries covered by AGOA.
Nonlinear Stability of Thin, Radially Stratified Disks

We perform local numerical experiments to investigate the nonlinear stability of thin, radially stratified disks. We demonstrate the presence of radial convective instability when the disk is nearly in uniform rotation and show that the net angular momentum transport is slightly inward, consistent with previous investigations of vertical convection. We then show that a convectively unstable equilibrium is stabilized by differential rotation. Convective instability is determined by the Richardson number Ri ? N/(?)2, where Nr is the radial Brunt-V?is?l? frequency and ? is the shear rate. Classical convective instability in a nonshearing medium (Ri ? -∞) is suppressed when Ri -1; i.e., when the shear rate becomes greater than the growth rate. Disks with a nearly Keplerian rotation profile and radial gradients on the order of the disk radius have Ri -0.01 and are therefore stable to local nonaxisymmetric disturbances. One implication of our results is that the "baroclinic" instability recently claimed by Klahr & Bodenheimer is either global or nonexistent. We estimate that our simulations would detect any genuine growth rate 0.0025?.
High-Power-Density Fault-Tolerant PM Generator for Safety-Critical Applications

Many safety-critical applications particularly in aviation require high-power (mass)-density generators with high reliability. While permanent-magnet (PM) machines promise significant improvements in power density and reliability, the widespread use of PM generators has been hitherto limited by the potentially detrimental effect of internal machine faults caused by the lack of de-excitation capability during fault conditions. Although there are several publications addressing fault-tolerant PM machines, most of these target auxiliary systems. In this paper, the detailed analysis, design, and test results of a 175-kW main power fault-tolerant embedded PM generator for aerospace applications will be presented. The design tradeoffs and the novel aspects of this machine will be discussed in detail.
Downstream Self-Destruction of Storm Tracks

The Northern Hemisphere storm tracks have maximum intensity over the Pacific and Atlantic basins; their intensity is reduced over the continents downstream. Here, simulations with an idealized aquaplanet general circulation model are used to demonstrate that even without continents, storm tracks have a self-determined longitudinal length scale. Their length is controlled primarily by the planetary rotation rate and is similar to thatofEarth’sstormtracksforEarth’srotationrate.Downstream, stormtracksself-destruct: thedownstream eddy kinetic energy is lower than it would be without the zonal asymmetries that cause localized storm tracks. Likely involved in the downstreamself-destruction ofstormtracks arethe energyfluxesassociatedwiththem. The zonalasymmetries that causelocalized stormtracksenhancetheenergytransport throughthe generation of stationary eddies, and this leads to a reduced baroclinicity that persists far downstream of the eddy kinetic energy maxima.
Multiscale analysis of morphology and mechanics in tail tendon from the ZDSD rat model of type 2 diabetes

Type 2 diabetes (T2D) impacts multiple organ systems including the circulatory, renal, nervous and musculoskeletal systems. In collagen-based tissues, one mechanism that may be responsible for detrimental mechanical impacts of T2D is the formation of advanced glycation end products (AGEs) leading to increased collagen stiffness and decreased toughness, resulting in brittle tissue behavior. The purpose of this study was to investigate tendon mechanical properties from normal and diabetic rats at two distinct length scales, testing the hypothesis that increased stiffness and strength and decreased toughness at the fiber level would be associated with alterations in nanoscale morphology and mechanics. Individual fascicles from female Zucker diabetic Sprague-Dawley (ZDSD) rats had no differences in fascicle-level mechanical properties but had increased material-level strength and stiffness versus control rats (CD). At the nanoscale, collagen fibril D-spacing was shifted towards higher spacing values in diabetic ZDSD fibrils. The distribution of nanoscale modulus values was also shifted to higher values. Material-level strength and stiffness from whole fiber tests were increased in ZDSD tails. Correlations between nanoscale and microscale properties indicate a direct positive relationship between the two length scales, most notably in the relationship between nanoscale and microscale modulus. These findings indicate that diabetes-induced changes in material strength and modulus were driven by alterations at the nanoscale.
Quality of mass-produced lead tungstate crystals

Because of the broad interest in high energy and nuclear physics community, mass production capacities of lead tungstate crystals have been established. The optical and scintillation properties of lead tungstate crystals, 20 each from two major vendors, were evaluated. The transmittance, emission and excitation spectra, light output and light response uniformity of these samples were measured. The degradations of these properties under irradiation, and the emission weighted radiation induced absorption coefficient (EWRIAC) were also studied. It was found that currently mass-produced lead tungstate crystals are radiation hard enough for radiation environments where expected dose rates do not exceed a few hundred rad/h.
Development of an Experimental Facility for Investigating Single-Phase Liquid Flow in Microchannels

An experimental facility has been developed to investigate single-phase liquid heat transfer and pressure drop in a variety of microchannel geometries. The facility is capable of accurately measuring the fluid temperatures, heater surface temperatures, heat transfer rates, and differential pressure in a test section. A microchannel test section with a silicon substrate is used to demonstrate the capability of the experimental facility. A copper resistor is fabricated on the backside of the silicon to provide heat input. Several other small copper resistors are used with a four-point measurement technique to acquire the heater temperature and calculate surface temperatures. A transparent pyrex cover is bonded to the chip to form the microchannel flow passages. The details of the experimental facility are presented here. The experimental facility is intended to support the collection of fundamental data in microchannel flows. It has the capability of optical visualization using a traditional microscope to s...
A sharp bound for the Castelnuovo–Mumford regularity of subspace arrangements

Abstract We show that the ideal of an arrangement of d linear subspaces of projective space is d -regular in the sense of Castelnuovo and Mumford, answering a question of B. Sturmfels. In particular, this implies that the ideal of an arrangement of d subspaces is generated in degrees less than or equal to d .
Bank Mergers, REIT Loan Pricing and Takeover Likelihood

The impact of bank mergers on Real Estate Investment Trust (REIT) loan pricing and takeover likelihood is assessed. REITs that lose their primary banking relationship due to bank mergers pay higher interest rates on future borrowings. Bank consolidation reduces bank competition for REIT loans which affects loan pricing. Moreover, based on randomly matched samples of REITs, the results imply that firms losing their agent banks due to bank mergers and those with limited access to bank debt are more likely to be acquired while REITs associated with acquiring banks are more likely to acquire other firms. Additional analysis of the 92 merged REITs reveals that 33% of the target REITs’ banks are merged with their REIT acquirers’ banks prior to the REIT mergers while 67% of the target REITs share at least one major bank with their acquirer.
The triangle closure is a polyhedron

Recently, cutting planes derived from maximal lattice-free convex sets have been studied intensively by the integer programming community. An important question in this research area has been to decide whether the closures associated with certain families of lattice-free sets are polyhedra. For a long time, the only result known was the celebrated theorem of Cook, Kannan and Schrijver who showed that the split closure is a polyhedron. Although some fairly general results were obtained by Andersen et al. (Math Oper Res 35(1):233---256, 2010) and Averkov (Discret Optimiz 9(4):209---215, 2012), some basic questions have remained unresolved. For example, maximal lattice-free triangles are the natural family to study beyond the family of splits and it has been a standing open problem to decide whether the triangle closure is a polyhedron. In this paper, we show that when the number of integer variables $$m=2$$ the triangle closure is indeed a polyhedron and its number of facets can be bounded by a polynomial in the size of the input data. The techniques of this proof are also used to give a refinement of necessary conditions for valid inequalities being facet-defining due to Cornuejols and Margot (Math Program 120:429---456, 2009) and obtain polynomial complexity results about the mixed integer hull.
Geometric characterization of series-parallel variable resistor networks

The range of operating conditions for a series-parallel network of variable linear resistors, voltage sources, and current sources can be represented as a convex polygon in a Thevenin or Norton half-plane. For a network with n elements of which k are variable, these polygons have at most 2k vertices and can be computed in O(nk) time. These half planes are embedded in the real projective plane to represent circuits with potentially infinite Thevenin resistance or Norton conductance. For circuits that have an acyclic structure once all branches to ground are removed, the characteristic polygons for all nodes with respect to ground can be computed simultaneously by an algorithm of complexity O(nk). >
Effect of Mean Stress on the Damage of Wind Turbine Blades

In many analyses of composite wind turbine blades, the effects of mean stress on the determination of damage are either ignored completely or they are characterized inadequately. An updated Goodman diagram for the fiberglass materials that are typically used in wind turbine blades has been released recently. This diagram, which is based on the MSU/DOE Fatigue Database, contains detailed information at thirteen Rvalues. This diagram is the most detailed to date, and it includes several loading conditions that have been poorly represented in earlier studies. This formulation allows the effects of mean stress on damage calculations to be evaluated. The evaluation presented here uses four formulations for the S-N behavior of the fiberglass. In the first analysis, the S-N curve for the composite is assumed to be independent of mean stress and to have a constant slope. The second is a linear Goodman diagram, the third is a bi-linear Goodman diagram and the fourth is the full Goodman diagram. Two sets of load spectra, obtained by the LIST (Long term Inflow and Structural Test) program, are used for this evaluation. The results of the analyses, equivalent fatigue loads and damage predictions, are compared to one another. These results illustrate a significant overestimation of the equivalent fatigue loads when the mean stress is not considered in the calculation. And, the results from the updated Goodman diagram illustrate that there are a significant differences in accumulated damage when the Goodman diagram
Stellar Velocity Dispersion in Dissipative Galaxy Mergers with Star Formation

In order to better understand stellar dynamics in merging systems, such as NGC 6240, we examine the evolution of central stellar velocity dispersion ( ) in dissipative galaxy mergers using a suite of binary disk merger simulations that include feedback from stellar formation and active galactic nuclei (AGNs). We nd that undergoes the same general stages of evolution that were observed in our previous dissipationless simulations: coherent oscillation, then phase mixing, followed by dynamical equilibrium. We also nd that measurements of that are based only upon the youngest stars in simulations consistently yield lower values than measurements based upon the total stellar population. This nding appears to be consistent with the so-called \ discrepancy," observed in real galaxies. We note that quasar-level AGN activity is much more likely to occur when is near its equilibrium value rather than during periods of extreme . Finally, we provide estimates of the scatter inherent in measuring in ongoing mergers. Subject headings: Galaxies: evolution, Galaxies: interactions, Galaxies: kinematics and dynamics, Methods: numerical
Coupled Decadal Variability in the North Pacific: An Observationally Constrained Idealized Model*

Abstract Air–sea coupled variability is investigated in this study by focusing on the observed sea surface temperature signals in the Kuroshio Extension (KE) region of 32°–38°N and 142°E–180°. In this region, both the oceanic circulation variability and the heat exchange variability across the air–sea interface are the largest in the midlatitude North Pacific. SST variability in the KE region has a dominant time scale of ∼10 yr and this decadal variation is caused largely by the regional, wind-induced sea surface height changes that represent the lateral migration and strengthening/weakening of the KE jet. The importance of the air–sea coupling in influencing KE jet is explored by dividing the large-scale wind forcing into those associated with the intrinsic atmospheric variability and those induced by the SST changes in the KE region. The latter signals are extracted from the NCEP–NCAR reanalysis data using the lagged correlation analysis. In the absence of the SST feedback, the intrinsic atmospheric for...
Non-analyticity in the large N renormalization group

Abstract The flow of the action induced by changing N is computed in large N matrix models. It is shown that the change in the action is non-analytic. This non-analyticity appears at the origin of the space of matrices if the action is even.
Support-Predicted Modified-CS for recursive robust principal components' Pursuit

This work proposes a causal and recursive algorithm for solving the “robust” principal components' analysis problem. We primarily focus on robustness to correlated outliers. In recent work, we proposed a new way to look at this problem and showed how a key part of its solution strategy involves solving a noisy compressive sensing (CS) problem. However, if the support size of the outliers becomes too large, for a given dimension of the current principal components' space, then the number of “measurements” available for CS may become too small. In this work, we show how to address this issue by utilizing the correlation of the outliers to predict their support at the current time; and using this as “partial support knowledge” for solving Modified-CS instead of CS.
Service Discovery and Device Identification in Cognitive Radio Networks

Cognitive radios (CR) will be able to communicate adaptively in an effort to optimize spectral efficiency. An integral step towards this goal involves obtaining a representative view of the various services operating in a local area. Although it is possible to load different software modules to identify each potential service, such an approach is needlessly inefficient. Instead, rather than use a collection of complete protocols on a CR, we believe that it is essential to have a separate identification module that is capable of reliably identifying services and devices while minimizing the code needed. In particular, by effectively leveraging protocol-specific properties, we show that it is possible to utilize data from narrowband spectral sampling in order to identify broader band services and individual devices. We demonstrate the feasibility of such service and device identification using GNU radio and the universal software radio peripheral (USRP) platform by identifying radio services in the industrial, scientific, and medical (ISM) radio band. Further, we show that physical layer signatures may be used to reliably identify devices, thereby allowing CRs to exploit physical layer information in support of basic authentication functionality.
The Economics of Small Worlds

We examine a simple economic model of network formation where agents bene…t from indirect relationships. We show that small-world features — short path lengths between nodes together with highly clustered link structures — necessarily emerge for a wide set of parameters.
Polycyclic aromatic compounds via radical cyclizations of benzannulated enyne-allenes derived from Ireland-Claisen rearrangement.

A new synthetic sequence involving the use of Ireland−Claisen rearrangement of propargylic acetates to form the corresponding benzannulated enyne-allenes followed by Schmittel cyclization to generate benzofulvene biradicals for radical cyclizations leading to polycyclic aromatic compounds was established. Treatment of 9-fluorenone (8) with the lithium acetylide 9 followed by acetic anhydride produced the propargylic acetate 10. A sequence of reactions occurred after 10 was converted to the corresponding silyl ketene acetal 11. An initial Ireland−Claisen rearrangement produced the benzannulated enyne-allene 12, which then underwent a Schmittel cyclization reaction to generate the benzofulvene biradical 13. A subsequent intramolecular radical−radical coupling then produced the formal Diels−Alder adduct 14, which in turn underwent a prototropic rearrangement to give the silyl ester 15 and, after hydrolysis, the carboxylic acid 16 in 57% overall yield from 10 in a single operation. An intramolecular acylation...
Consistency in dataflow graphs

This paper describes an analytical model for the behavior of dataflow graphs with data-dependent control flow. The number of tokens produced or consumed by each actor is given as a symbolic function of the Booleans in the system. Long term averages can be analyzed to determine consistency of token flow rates, which in turn determines whether memory requirements are bounded. Short-term behavior can be analyzed to construct an annotated schedule, or a static schedule that annotates each firing of an actor with the Boolean conditions under which that firing occurs. Annotated schedules can be used to generate efficient implementations of the algorithms given by the dataflow graphs. >
Copper-catalyzed synthesis of vinyl sulfides.

We report a method for the synthesis of vinyl sulfides using the soluble copper(I) catalyst [Cu(phen)(PPh3)2]NO3. The desired vinyl sulfides are obtained in good to excellent yields, with retention of stereochemistry. This protocol tolerates a wide variety of functional groups or substrates, is palladium-free, and does not require the use of expensive or air-sensitive additives.
Creation of electron–positron wind in gamma-ray bursts and its effect on the early afterglow emission

We calculate the creation of electron-positron pairs in gamma-ray bursts (GRBs) resulting from the collision between scattered and outward-moving gamma-ray photons. The number of pairs exceeds the number of ambient-medium electrons encountered by the GRB ejecta up to ∼10 16 cm from the centre of explosion. The shock resulting from the interaction of the ejecta with the pair wind may increase the afterglow synchrotron emission peak flux, in the optical band, during the first few minutes by a factor of less than about 5. The peak intensity of the optical afterglow increases with the density of the surrounding medium. Therefore, observations of the optical flux at early times constrain the density of the circumburst medium. If the electron and magnetic field energies behind the forward shock sweeping up the pair wind and the circumburst medium are as inferred from fits to the broad-band afterglow emission at 0.5-100 d, then the current upper limits on the optical counterpart emission, set by the ROTSE and LOTIS experiments, indicate that the circumburst medium within 0.01 pc is less dense than 100 cm -3 or, if a wind, corresponds to a progenitor mass-loss to wind-speed ratio below 10 -6 M ○. yr -1 /(10 3 km s -1 ).
Learning and verifying quantified boolean queries by example

To help a user specify and verify quantified queries --- a class of database queries known to be very challenging for all but the most expert users --- one can question the user on whether certain data objects are answers or non-answers to her intended query. In this paper, we analyze the number of questions needed to learn or verify qhorn queries, a special class of Boolean quantified queries whose underlying form is conjunctions of quantified Horn expressions. We provide optimal polynomial-question and polynomial-time learning and verification algorithms for two subclasses of the class qhorn with upper constant limits on a query's causal density.
The wage gains of african-american women in the 1940s

The 1940s marked a turning point in the labor market outcomes of African-American women. They experienced large wage gains relative to white women, sharp declines in agricultural and domestic service work, and significant increases in formal sector employment. Using a semiparametric decomposition technique, we assess the influence of changes in productive and personal characteristics, in workers' distribution across occupations and locations, and in the wage structure on both black women's absolute wage gains and those relative to white women's. We argue that the pattern of changes is most consistent with increasing demand for their labor in the formal sector.
Synthesis and structure of bis(1,1-diethyl-3-(2-chlorobenzoyl)thioureido)nickel(II)

Abstract The Ni(II) complex of 1,1-diethyl-3-(2-chlorobenzoyl) thiourea (L) was synthesized and its crystal structure determined by X-ray crystallography. NiL2 is monoclinic, space group P2l/c(#14), with a=8.229, b=39.277, c=8.485 A, β=96.8°. The Ni(II) is coordinated in a planar fashion by two S and two O atoms in a cis arrangement. The NiS and NiO bond lengths are approximately 2.14 and 1.84 A respectively, with the two bonds of each type differing only slightly. The SNiS and O NiO bond angles are 87.6° and 83.0° respectively, but with considerable expansion of the ligand bond angles in the chelate ring. The crystal structure of the free ligand was also determined to compare free and complex bond lengths and angles. It is orthorhombic, space group Pbca(#61), with a=9.856, b=10.128 and c= 26.848 A.
Topological defects in graphene: Dislocations and grain boundaries

Topological defects in graphene, dislocations and grain boundaries, are still not well understood despite the considerable number of experimental observations. We introduce a general approach for constructing dislocations in graphene characterized by arbitrary Burgers vectors as well as grain boundaries, covering the whole range of possible misorientation angles. By using ab initio calculations we investigate thermodynamic and electronic properties of these topological defects, finding energetically favorable symmetric large-angle grain boundaries, strong tendency toward out-of-plane deformation in the small-angle regimes, and pronounced effects on the electronic structure. The present results show that dislocations and grain boundaries are important intrinsic defects in graphene which may be used for engineering graphene-based nanomaterials and functional devices.
Isomorphism and Morita equivalence of graph algebras

For any countable graph E, we investigate the relationship between the Leavitt path algebra L ℂ (E) and the graph C * -algebra C * (E). For graphs E and F, we examine ring homomorphisms, ring *-homomorphisms, algebra homomorphisms, and algebra *-homomorphisms between L ℂ (E) and L ℂ (F). We prove that in certain situations isomorphisms between L ℂ (E) and L ℂ (F) yield *-isomorphisms between the corresponding C * -algebras C * (E) and C * (F). Conversely, we show that *-isomorphisms between C * (E) and C * (F) produce isomorphisms between L ℂ (E) and L ℂ (F) in specific cases. The relationship between Leavitt path algebras and graph C * -algebras is also explored in the context of Morita equivalence.
Convenient preparation of naphthyridines from halopyridines: sequential Heck coupling and cyclization

Abstract A simple method for the preparation of 1,7-naphthyridine and 1,6-naphthyridine from the corresponding aminopyridine starting materials is presented.
Probing the Sheath Electric Field With a Crystal Lattice by Using Thermophoresis in Dusty Plasma

A 2-D dust crystal levitated in the sheath of a modified Gaseous Electronics Conference reference cell is manipulated by heating or cooling the lower electrode. The dust charge is obtained by measuring the global characteristics of the levitated crystal obtained from top-view pictures. From the force balance, the electric field in the sheath is reconstructed. From the Bohm criterion, we conclude that the dust crystal is levitated mainly above and just below the classical Bohm point.
Depths of Powers of the Edge Ideal of a Tree

Lower bounds are given for the depths of R/I t for t ≥ 1 when I is the edge ideal of a tree or forest. The bounds are given in terms of the diameter of the tree, or in case of a forest, the largest diameter of a connected component and the number of connected components. These lower bounds provide a lower bound on the power for which the depths stabilize.
Symbolic Software for the Painleve Test of Nonlinear Ordinary and Partial Differential Equations

The automation of the traditional Painleve test in Mathematica is discussed. The package PainleveTest.m allows for the testing of polynomial systems of nonlinear ordinary and partial differential equations which may be parameterized by arbitrary functions (or constants). Except where limited by memory, there is no restriction on the number of independent or dependent variables. The package is quite robust in determining all the possible dominant behaviors of the Laurent series solutions of the differential equation. The omission of valid dominant behaviors is a common problem in many implementations of the Painleve test, and these omissions often lead to erroneous results. Finally, our package is compared with the other available implementations of the Painleve test.
Stratospheric ozone depletion

Solar ultraviolet radiation creates an ozone layer in the atmosphere which in turn completely absorbs the most energetic fraction of this radiation. This process both warms the air, creating the stratosphere between 15 and 50 km altitude, and protects the biological activities at the Earth's surface from this damaging radiation. In the last half-century, the chemical mechanisms operating within the ozone layer have been shown to include very efficient catalytic chain reactions involving the chemical species HO, HO2, NO, NO2, Cl and ClO. The NOX and ClOX chains involve the emission at Earth's surface of stable molecules in very low concentration (N2O, CCl2F2, CCl3F, etc.) which wander in the atmosphere for as long as a century before absorbing ultraviolet radiation and decomposing to create NO and Cl in the middle of the stratospheric ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the stratosphere, with the result that more solar ultraviolet-B radiation (290–320 nm wavelength) reaches the surface. This ozone loss occurs in the temperate zone latitudes in all seasons, and especially drastically since the early 1980s in the south polar springtime—the ‘Antarctic ozone hole’. The chemical reactions causing this ozone depletion are primarily based on atomic Cl and ClO, the product of its reaction with ozone. The further manufacture of chlorofluorocarbons has been banned by the 1992 revisions of the 1987 Montreal Protocol of the United Nations. Atmospheric measurements have confirmed that the Protocol has been very successful in reducing further emissions of these molecules. Recovery of the stratosphere to the ozone conditions of the 1950s will occur slowly over the rest of the twenty-first century because of the long lifetime of the precursor molecules.
Kinematics Meets Crystallography: The Concept of a Motion Space

In this paper, it is shown how rigid-body kinematics can be used to assist in determining the atomic structure of proteins and nucleic acids when using x-ray crystallography, which is a powerful method for structure determination. The importance of determining molecular structures for understanding biological processes and for the design of new drugs is well known. Phasing is a necessary step in determining the three-dimensional structure of molecules from x-ray diffraction patterns. A computational approach called molecular replacement (MR) is a well-established method for phasing of x-ray diffraction patterns for crystals composed of biological macromolecules. In MR, a search is performed over positions and orientations of a known biomolecular structure within a model of the crystallographic asymmetric unit, or, equivalently, multiple symmetry-related molecules in the crystallographic unit cell. Unlike the discrete space groups known to crystallographers and the continuous rigid-body motions known to kinematicians, the set of motions over which molecular replacement searches are performed does not form a group. Rather, it is a coset space of the group of continuous rigid-body motions, SE(3), with respect to the crystallographic space group of the crystal, which is a discrete sub-group of SE(3). Properties of these ‘motion spaces’ (which are compact manifolds) are investigated here.Copyright © 2014 by ASME
Limited role of entropy in information economics

‘Information transmitted’ is defined as the amount by which added evidence (or ‘message received’) diminishes ‘uncertainty’. The latter is characterized by some properties intuitively suggested by this word and possessed by conditional entropy, a parameter of the posterior probability distribution. However, conditional entropy shares these properties with some other concave symmetric functions on the probability space. Moreover, a given transmission channel (or, in the context of statistical inference, a given experiment) yields a higher maximum expected benefit than anotherto any user if and only ifall concave functions of the posterior probability vector have higher values for the former channel (or experiment). Hence one information system (channel, experiment) may be preferable to another for a given user although its transmission rate, in entropy terms, is lower. But only entropy has the economically relevant property of measuring, in the limit, the expected length of efficiently coded messages sent in long sequences. Thus, while irrelevant to the value (maximum expected benefit) of an information system and to the costs of observing, estimating, and deciding, entropy formulas are indeed relevant to the cost of communicating, i.e., of storing, coding and transmitting messages.
A practical microgripper by fine alignment, eutectic bonding and SMA actuation

Abstract A microgripper with a large gripping force, a relatively rigid structural body, and flexibility in functional design is presented. The actuation is generated by NiTiCu shape memory alloy (SMA) films and the stress induced can deflect each side of the microgripper up to 55 μm for a total gripping motion of 110 μm. When fully open, the force exerted by the film corresponds to a 13 mN gripping force on the tip of the gripper.