cssi/SciSciGPT-SciSciNet huggingface dataset:
Long Time Dynamics of Forced Critical SQG

We prove the existence of a compact global attractor for the dynamics of the forced critical surface quasi-geostrophic equation (SQG) and prove that it has finite fractal (box-counting) dimension. In order to do so we give a new proof of global regularity for critical SQG. The main ingredient is the nonlinear maximum principle in the form of a nonlinear lower bound on the fractional Laplacian, which is used to bootstrap the regularity directly from L ∞ to C α, without the use of De Giorgi techniques. We prove that for large time, the norm of the solution measured in a sufficiently strong topology becomes bounded with bounds that depend solely on norms of the force, which is assumed to belong merely to L ∞ ∩ H 1. Using the fact that the solution is bounded independently of the initial data after a transient time, in spaces conferring enough regularity, we prove the existence of a compact absorbing set for the dynamics in H 1, obtain the compactness of the linearization and the continuous differentiability of the solution map. We then prove exponential decay of high yet finite dimensional volume elements in H 1 along solution trajectories, and use this property to bound the dimension of the global attractor.
Weak disorder in Fibonacci sequences

We study how weak disorder affects the growth of the Fibonacci series. We introduce a family of stochastic sequences that grow by the normal Fibonacci recursion with probability 1 − , but follow a different recursion rule with a small probability . We focus on the weak disorder limit and obtain the Lyapunov exponent that characterizes the typical growth of the sequence elements, using perturbation theory. The limiting distribution for the ratio of consecutive sequence elements is obtained as well. A number of variations to the basic Fibonacci recursion including shift, doubling and copying are considered.
Maternal pre-pregnancy BMI, gestational weight gain, and infant birth weight: A within-family analysis in the United States

In the United States, the high prevalence of unhealthy preconception body weight and inappropriate gestational weight gain among pregnant women is an important public health concern. However, the relationship among pre-pregnancy BMI, gestational weight gain, and newborn birth weight has not been well established. This study uses a very large dataset of sibling births and a within-family design to thoroughly address this issue. The baseline analysis controlling for mother fixed effects indicates maternal preconception overweight, preconception obesity, and excessive gestational weight gain significantly increase the risk of having a high birth weight baby, respectively, by 1.3, 3 and 3.9 percentage points, while underweight before pregnancy and inadequate gestational weight gain increase the low birth weight incidence by 1.4 and 2 percentage points. The benchmark results are robust in a variety of sensitivity checks. Since poor birth outcomes especially high birth weight and low birth weight have lasting adverse impacts on one's health, education, and socio-economic outcomes later in life, the findings of this research suggest promoting healthy weight among women before pregnancy and preventing inappropriate weight gain during pregnancy can generate significant intergenerational benefits.
Evolution of grains in a turbulent solar nebula

In the present computation of the evolution of grain size distribution in a turbulent disk for turbulent solar nebula models, using realistic collisional outcomes and strengths of grain aggregates, the half space above the central plane of the disk is divided into a series of levels. At each level, the size distribution is represented by the population of a series of discrete size bins, each spanning an order of magnitude in mass. Coagulation, erosion, or disruption, occur for various combinations of relative particle sizes and velocities, together with assumed material strength, based on experimental impact data. The calculation is one-dimensional, in that it is performed at a single radial location in the disk.
Three-dimensional structures of oligosaccharides

Oligosaccharides represent a particularly challenging class of molecules for conformational analysis. Recent advances in experimental and theoretical methods have begun to yield further insight into their conformational behavior; however, general rules governing their conformational preferences have not yet emerged. X-ray and NMR techniques may provide vital insights into protein-bound oligosaccharide conformations, but these do not necessarily represent highly populated solution conformations. Moreover, an oligosaccharide's inherent flexibility and lack of strong intermolecular interactions places extreme demands on theoretical methods.
Aircraft Approach Guidance Using Relative Loran‐C Navigation

Precision navigation about a reference point using Loran-C can be achieved by subtracting the Loran Time Differences measured at the reference point from the received Time Differences, thus reducing by common-mode cancellation the effect of variations in signal propagation velocity; a potential application of this technique is aircraft final approach guidance. In addition to the classical Geometric Dilution of Precision, performance of Loran-C in this “relative navigation” mode is limited by reference datum accuracy, by the response of the receiver's tracking loops to noise and vehicle accelerations, and by local deformations in the shape of the Lines of Position grid. Optimization of the receiver's tracking loop bandwidth can result in an expected performance of 45 meters (2-σ) for a 0 dB signal to noise ratio and typical aircraft low-approach maneuvering accelerations. Ground-level measurements at this level of precision indicate the existence of a “grid microdeformation”: localized, repeatable distortions of the Lines of Position over distances much smaller than the carrier wavelength. It is concluded that 2-σ horizontal accuracies of 100 meters or less are realistically achievable with relative Loran-C if signal to noise ratio and maneuvering acceleration limits are specified. This accuracy is significantly better than that of VOR or NDB approach systems, but not as good as an ILS Localizer.
Faraday Rotation in Global Accretion Disk Simulations: Implications for Sgr A*

We calculate Faraday rotation in global axisymmetric MHD simulations of geometrically thick accretion flows. These calculations are motivated by the measured rotation measure (RM) ≈ − 6 × 105 rad m−2 from Sgr A* in the Galactic center, which appears to have been stable over the past ≈7 yr. In our numerical simulations, the quasi-steady state structure of the accretion flow, as well as the RM it produces, depends on the initial magnetic field threading the accreting material. In spite of this dependence, we can draw several robust conclusions about Faraday rotation produced by geometrically thick accretion disks: (1) the time-averaged RM does not depend that sensitively on the viewing angle through the accretion flow, but the stability of the RM can. Equatorial viewing angles show significant variability in RM (including sign reversals), while polar viewing angles are relatively stable if there is a large-scale magnetic field threading the disk at large radii. (2) Most of the RM is produced at small radii for polar viewing angles, while all radii contribute significantly near the midplane of the disk. Our simulations confirm previous analytic arguments that the accretion rate onto Sgr A* must satisfy in Bondi ~ 10−5 M☉ yr −1 in order to not overproduce the measured RM. We argue that the steady RM ≈ − 6 × 105 rad m−2 from Sgr A* has two plausible explanations: (1) It is produced at ~100 Schwarzschild radii, requires in ≈ 3 × 10−8 M☉ yr −1 , and we view the flow at an angle of ~30° relative to the rotation axis of the disk. (2) Alternatively, the RM may be produced in the relatively spherical inflowing plasma near the circularization radius at ~103-104 Schwarzschild radii. Time variability studies of the RM can distinguish between these two possibilities.
Theory of Lipid Polymorphism: Application to Phosphatidylethanolamine and Phosphatidylserine

We introduce a microscopic model of a lipid with a charged headgroup and flexible hydrophobic tails, a neutral solvent, and counter ions. Short-ranged interactions between hydrophilic and hydrophobic moieties are included as are the Coulomb interactions between charges. Further, we include a short-ranged interaction between charges and neutral solvent, which mimics the short-ranged, thermally averaged interaction between charges and water dipoles. We show that the model of the uncharged lipid displays the usual lyotropic phases as a function of the relative volume fraction of the headgroup. Choosing model parameters appropriate to dioleoylphosphatidylethanolamine in water, we obtain phase behavior that agrees well with experiment. Finally we choose a solvent concentration and temperature at which the uncharged lipid exhibits an inverted hexagonal phase and turn on the headgroup charge. The lipid system makes a transition from the inverted hexagonal to the lamellar phase, which is related to the increased waters of hydration correlated with the increased headgroup charge via the charge-solvent interaction. The polymorphism displayed upon variation of pH mimics that of the behavior of phosphatidylserine.
Supernova neutrino-nucleus astrophysics

In this brief review we explore the role of neutrino-nucleus interactions in core-collapse supernovae and discuss open questions. In addition implications of neutrino mass and mixings in such environments are summarized.
Clustering, Agency Costs and Operating Efficiency: Evidence from Nursing Home Chains

Models of horizontal integration typically describe a trade-off between multiunit efficiencies and managerial agency costs. In extreme cases where managers cannot be incented contractually, private ownership is thought to be the primary organizational substitute. In this paper we explore geographic clustering as an alternative strategy for controlling managerial agency costs within the chain form of organization. Clustering may facilitate scale efficiencies in both monitoring and supervision, resulting in reduced agency costs and improved application of the chain's business model. We test this hypothesis in the nursing home industry, which is characterized by managerial contract costs resulting from multitask models of production. We find that clustered nursing homes achieve higher quality, conditional on labor inputs and patient characteristics. The clustering effect is concentrated on reductions in minor/potential harm violations, which are difficult to observe without close monitoring. Several proxies for local organizational experience “local learning” cannot account for our findings, which are robust to a variety of alternative clustering definitions and competing explanations based on gaming behavior. Further tests indicate that chains endogenously pursue clustering, presumably to realize the benefits of improved quality outcomes. This paper was accepted by Bruno Cassiman, business strategy.
The mass renormalization of nonperturbative light-front Hamiltonian theory: an illustration using truncated, Pauli–Villars-regulated Yukawa interactions

Abstract We obtain analytic, nonperturbative, approximate solutions of Yukawa theory in the one-fermion sector using light-front quantization. The theory is regulated in the ultraviolet by the introduction of heavy Pauli–Villars scalar and fermion fields, each with negative norm. In order to obtain a directly soluble problem, fermion-pair creation and annihilation are neglected, and the number of bosonic constituents is limited to one of either type. We discuss some of the features of the wave function of the eigensolution, including its endpoint behavior and spin and orbital angular momentum content. The limit of infinite Pauli–Villars mass receives special scrutiny.
Additive preconditioning for matrix computations

Abstract Our randomized additive preconditioners are readily available and regularly facilitate the solution of linear systems of equations and eigen-solving for a very large class of input matrices. We study the generation of such preconditioners and their impact on the rank and the condition number of a matrix. We also propose some techniques for their refinement and two alternative versions of randomized preprocessing. Our analysis and experiments show the power of our approach even where we employ weak randomization, that is generate sparse and structured preconditioners, defined by a small number of random parameters.
Data-driven interaction techniques for improving navigation of educational videos

With an unprecedented scale of learners watching educational videos on online platforms such as MOOCs and YouTube, there is an opportunity to incorporate data generated from their interactions into the design of novel video interaction techniques. Interaction data has the potential to help not only instructors to improve their videos, but also to enrich the learning experience of educational video watchers. This paper explores the design space of data-driven interaction techniques for educational video navigation. We introduce a set of techniques that augment existing video interface widgets, including: a 2D video timeline with an embedded visualization of collective navigation traces; dynamic and non-linear timeline scrubbing; data-enhanced transcript search and keyword summary; automatic display of relevant still frames next to the video; and a visual summary representing points with high learner activity. To evaluate the feasibility of the techniques, we ran a laboratory user study with simulated learning tasks. Participants rated watching lecture videos with interaction data to be efficient and useful in completing the tasks. However, no significant differences were found in task performance, suggesting that interaction data may not always align with moment-by-moment information needs during the tasks.
Effectiveness of feature and classifier algorithms in character recognition systems

At the first Census Optical Character Recognition Systems Conference, NIST generated accuracy data for more than character recognition systems. Most systems were tested on the recognition of isolated digits and upper and lower case alphabetic characters. The recognition experiments were performed on sample sizes of 58,000 digits, and 12,000 upper and lower case alphabetic characters. The algorithms used by the 26 conference participants included rule-based methods, image-based methods, statistical methods, and neural networks. The neural network methods included Multi-Layer Perceptron's, Learned Vector Quantitization, Neocognitrons, and cascaded neural networks. In this paper 11 different systems are compared using correlations between the answers of different systems, comparing the decrease in error rate as a function of confidence of recognition, and comparing the writer dependence of recognition. This comparison shows that methods that used different algorithms for feature extraction and recognition performed with very high levels of correlation. This is true for neural network systems, hybrid systems, and statistically based systems, and leads to the conclusion that neural networks have not yet demonstrated a clear superiority to more conventional statistical methods. Comparison of these results with the models of Vapnick (for estimation problems), MacKay (for Bayesian statistical models), Moody (for effective parameterization), and Boltzmann models (for information content) demonstrate that as the limits of training data variance are approached, all classifier systems have similar statistical properties. The limiting condition can only be approached for sufficiently rich feature sets because the accuracy limit is controlled by the available information content of the training set, which must pass through the feature extraction process prior to classification.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
SEAMONSTER: A demonstration sensor web operating in virtual globes

A sensor web is a collection of heterogeneous sensors which autonomously reacts to the observed environment. The SouthEast Alaska MOnitoring Network for Science, Technology, Education, and Research (SEAMONSTER) project has implemented a sensor web in partially glaciated watersheds near Juneau, Alaska, on the edge of the Juneau Icefield. By coupling the SEAMONSTER sensor web with digital earth technologies the scientific utility, education and public outreach efforts, and sensor web management of the project all greatly benefit. This paper describes the scientific motivation for a sensor web, the technology developed to implement the sensor web, the software developed to couple the sensor web with digital earth technologies, and demonstrates the SEAMONSTER sensor web in a digital earth framework.
Fasting Glucose Insulin Ratio: A Useful Measure of Insulin Resistance in Girls with Premature Adrenarche

The purpose of this study was to determine whether the fasting glucose/insulin ratio is a useful screening test for insulin resistance in prepubertal girls with premature adrenarche. The glucose/insulin ratio was compared with the insulin sensitivity index calculated from the frequently sampled iv glucose tolerance test with tolbutamide using the minimal model computer program. Thirty-three prepubertal girls (22 Caribbean Hispanic and 11 African American; mean age, 6.8 yr; bone age, 8 yr) were studied. All underwent a 60-min ACTH stimulation test. The fasting glucose/insulin ratio was also compared with IGF-binding protein-1 and ACTH-stimulated androgen levels. Insulin sensitivity correlated significantly with the glucose/insulin ratio (0.76; P 5.7 x 10(-4) min/microU.ml), the sensitivity of the fasting glucose/insulin ratio was 87%, and the specificity was 89%. Furthermore, those girls with a low glucose/insulin ratio (<7) had higher body mass index, fasting insulin, free T, and ACTH-stimulated 17-hydroxypregnenolone and lower fasting IGF-binding protein-1 and SHBG than those girls with a glucose/insulin ratio greater than 7. The fasting glucose/insulin ratio is a useful screening test for insulin resistance in prepubertal Caribbean Hispanic and African American girls with premature adrenarche.
Pledgability and Liquidity: A New Monetarist Model of Financial and Macroeconomic Activity

When limited commitment hinders unsecured credit, assets help by serving as collateral. We study models where assets differ in pledgability - the extent to which they can be used to secure loans - and hence liquidity. Although many previous analyses of imperfect credit focus on producers, we emphasize consumers. Household debt limits are determined by the cost households incur when assets are seized in the event of default. The framework, which nests standard growth and asset-pricing theory, is calibrated to analyze the effects of monetary policy and financial innovation. We show that inflation can raise output, employment and investment, plus improve housing and stock markets. For the baseline calibration, optimal inflation is positive. Increases in pledgability can generate booms and busts in economic activity, but may still be good for welfare.
Synthesis of Acyclothymidine Triphosphate and α-P-Boranotriphosphate and Their Substrate Properties with Retroviral Reverse Transcriptase

The first example of an acyclonucleoside α-P-boranotriphosphate has been synthesized via a phosphoramidite approach in a one-pot reaction with good yield. The presence of the α-P-BH3 in 5b results in a 9-fold increase in efficiency of incorporation by MMLV retroviral reverse transcriptase relative to non-boronated 5a in pre-steady-state conditions. The preliminary results indicate that acyclonucleoside α-P-boranotriphosphates may have promising applications as a probe of enzyme mechanisms and in the design of new antiviral drugs.
Observed Climate–Snowpack Relationships in California and their Implications for the Future

Abstract A study of the California Sierra Nevada snowpack has been conducted using snow station observations and reanalysis surface temperature data. Monthly snow water equivalent (SWE) measurements were combined from two datasets to provide sufficient data from 1930 to 2008. The monthly snapshots are used to calculate peak snow mass timing for each snow season. Since 1930, there has been an overall trend toward earlier snow mass peak timing by 0.6 days per decade. The trend toward earlier timing also occurs at nearly all individual stations. Even stations showing an increase in 1 April SWE exhibit the trend toward earlier timing, indicating that enhanced melting is occurring at nearly all stations. Analysis of individual years and stations reveals that warm daily maximum temperatures averaged over March and April are associated with earlier snow mass peak timing for all spatial and temporal scales included in the dataset. The influence is particularly pronounced for low accumulation years indicating the ...
Damage detection in concrete using Lamb waves

The feasibility of detecting defects in concrete beams using Lamb waves is investigated in this paper. The Lamb wave can propagate a long distance along the specimen as the guided wave and is sensitive to defects that are smaller than its wavelength. The traditional ultrasonic methods for inspecting defects in concrete use reflection, transmission and scattering of longitudinal waves by internal defects. In traditional techniques signal amplitude and time of flight measurements provide information about the internal defects in concrete. These methods are time consuming and often fail to detect a variety of defects, such as internal corrosion, honeycombs, closed cracks and small inclusions. In this paper Lamb waves are used to detect those defects in concrete beams with and without reinforcement. The Lamb wave technique is found to be reliable for detecting such defects. The effect of separation or delamination between concrete and reinforcing steel bars on the Lamb wave propagation characteristics is also investigated. Corrosion of rebars can cause this delamination. It is found that the cylindrical guided waves propagating along the steel rebars are very sensitive to the degree of delamination between the concrete and the rebars. This investigation shows that the Lamb wave inspection technique is an efficient and effective tool for health monitoring of concrete structures.
Comments on a-maximization from gauged supergravity

In this paper we study the holographic dual to a-maximization in five-dimensional $ \mathcal{N}=2 $ gauged supergravity. In particular, we apply the procedure described by Tachikawa in [1] to specific examples consisting of holographic duals to gauge theories arising as the IR limit of N M5-branes wrapping a Riemann surface. A key element of this analysis is a consistent truncation of seven-dimensional $ \mathcal{N}=4 $ SO(5) gauged supergravity reduced on a Riemann surface. We demonstrate the consistency of this truncation and match to a sector of five-dimensional matter-coupled $ \mathcal{N}=2 $ gauged supergravity. We determine the U(1) R symmetry and central charge of these theories and find agreement with the literature. The final results provide a nontrivial illustration of the holographic interpretation of a-maximization.
The shocking development of lithium (and boron) in supernovae

It is shown that significant amounts of Li-7 and B-11 are produced in Type 2 supernovae. The synthesis of these rare elements occurs as the supernova shock traverses the base of the hydrogen envelope burning He-3 to masses 7 and 11 via alpha capture. The yields in this process are sufficient to account for the difference in lithium abundance observed between Pop 2 and Pop 1 stars. Since lithium (and boron) would, in this manner, be created in the same stars that produce the bulk of the heavy elements, the lithium abundance even in old Pop 1 stars would be high (as observed). The B-11 production may remedy the long-standing problem of the traditional spallation scenario to account for the observed isotopic ratio of boron. Observational consequences of this mechanism are discussed, including the evolution of lithium and boron isotope ratios in the Galaxy and the possible use of the boron yields to constrain the number of blue progenitor Type 2 supernovae.
Binding of tissue plasminogen activator to human umbilical vein endothelial cells.

Abstract Binding of purified recombinant human tissue plasminogen activator to cultures of human umbilical vein endothelial cells (HUVEC) was studied in vitro. 125 I-tPA was shown to bind to HUVEC in a specific, saturable, and dissociable manner. Scatchard analysis revealed a low affinity binding site with K eq =4.2 × 10M −1 and 1.2 × 10 7 sites per cell. Binding of tPA was inhibited by L-lysine, e-aminocaproic acid, and D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone but not by carbohydrates including mannose, galactose, N-acetyl glucosamine and N-acetyl galactosamine. Neat human plasma abrogates but does not totally inhibit binding of tPA to HUVEC. These results may indicate a role for endothelial cells in the removal of tPA from the circulation in vivo.
METHOD OF OBTAINING CONSUMER WELFARE FROM REGIONAL TRAVEL DEMAND MODELS

The need for more comprehensive traveler welfare measures is highlighted by the U.S. Intermodal Surface Transportation Efficiency Act (1991) requirement that transportation projects and plans be evaluated for economic efficiency. However, to date, there has been a discrepancy between this requirement and the methods used by regional transportation organizations to evaluate transportation policies in the United States. Kenneth Small and Harvey Rosen illustrate how a consumer welfare measure known as compensating variation can be obtained from discrete choice models. A method of application is developed for the mode choice models in the Sacramento Regional Travel Demand Model. The results of the method's application to the model for light rail transit, high-occupancy vehicle lanes, and auto pricing scenarios are examined for both total consumer welfare and consumer welfare by income class.
Following multiple unpredictable coherent targets among obstacles

Camera control is essential in both virtual and real-world environments. The quality of the camera's placement and motion may spell the difference between usability and confusion. Our work focuses on an instance of camera control called target following, and offers an algorithm for following multiple targets with unpredictable trajectories, among known obstacles. To the best of our knowledge, this work is the first attempting to address this important problem.
M theory and the light cone

I discuss D0-brane quantum mechanics as a nonperturbative formulation of string theory, in particular the relation between the Banks-Fischler-Shenker-Susskind matrix model, the Maldacena conjecture for D0-branes, and type IIA/M-theory duality. Some features of the quantum mechanics of D0-branes are also discussed. Lecture presented at the Nishinomiya-Yukawa Memorial Symposium, Nov. 1998.
Controlling Policy by Controlling Process: Judicial Influence on Regulatory Decision Making

In this article, the ability of a federal appellate court to control agency policy by imposing process requirements upon the agency is analyzed under two administrative law regimes: the deference doctrine, where appellate courts are strictly limited in their ability to interfere with agency decision making, and the nondeference doctrine, where courts have greater reign in scrutinizing agency decision making. The emphasis on the judiciary's ability to affect regulatory process complements earlier scholarship in positive political theory that focused mainly on Congress' ability to use administrative process to control agency behavior. A model of judicial control is developed to allow for comparative statics considering different legal doctrines, shifting agency and judicial preferences, and changing agency resources. An examination of the Federal Energy Regulatory Commission and the D.C. Circuit Court of Appeals' battle over the deregulation of oil pipelines is undertaken to illustrate the insights of the model. Further evidence bearing on
The double-dark portal

In most models of the dark sector, dark matter is charged under some new symmetry to make it stable. We explore the possibility that not just dark matter, but also the force carrier connecting it to the visible sector is charged under this symmetry. This dark mediator then acts as a Double-Dark Portal. We realize this setup in the dark mediator Dark matter model (dmDM), featuring a fermionic DM candidate χ with Yukawa couplings to light scalars ϕ i . The scalars couple to SM quarks via the operator $$ \overline{q}q{\phi}_i^{\ast }{\phi}_j/{\varLambda}_{ij} $$ . This can lead to large direct detection signals via the 2 → 3 process χN → χN ϕ if one of the scalars has mass ≲ 10 keV. For dark matter Yukawa couplings y χ ∼ 10−3 −10−2, dmDM features a thermal relic dark matter candidate while also implementing the SIDM scenario for ameliorating inconsistencies between dwarf galaxy simulations and observations. We undertake the first systematic survey of constraints on light scalars coupled to the SM via the above operator. The strongest constraints are derived from a detailed examination of the light mediator’s effects on stellar astrophysics. LHC experiments and cosmological considerations also yield important bounds. Observations of neutron star cooling exclude the minimal model with one dark mediator, but a scenario with two dark mediators remains viable and can give strong direct detection signals. We explore the direct detection consequences of this scenario and find that a heavy $$ \mathcal{O}\left(100\mathrm{GeV}\right) $$ dmDM candidate fakes different $$ \mathcal{O}\left(10\mathrm{GeV}\right) $$ WIMPs at different experiments. Large regions of dmDM parameter space are accessible above the irreducible neutrino background.
Effects of a tungsten addition on the morphological evolution, spatial correlations and temporal evolution of a model Ni-Al-Cr superalloy

Abstract The effect of adding 2 at.% W to a model Ni–Al–Cr superalloy on the morphological evolution, spatial correlations and temporal evolution of γ′(L12)-precipitates at 1073 K is studied with scanning electron microscopy and atomic force microscopy. Adding W yields a larger microhardness, earlier onset of spheroidal-to-cuboidal precipitate morphological transition, larger volume fraction (from ∼20% to 30%), reduction in coarsening kinetics by one-third and a larger number density (Nv) of smaller mean radii (〈R〉) precipitates. The kinetics of 〈R〉 and interfacial area per unit volume obey t1/3 and t−1/3 relationships, respectively, which is consistent with coarsening driven by interfacial energy reduction. The Nv power-law dependencies deviate, however, from model predictions, indicating that a stationary state is not achieved. Quantitative analyses with precipitate size distributions, pair correlation functions and edge-to-edge interprecipitate distance distributions give insight into two-dimensional microstructural evolution, including the elastically driven transition from a uniform γ′-distribution to one-dimensional 〈0 0 1〉-strings to eventually clustered packs of γ′-precipitates in the less densely packed Ni–Al–Cr alloy.
An XMM-Newton Observation of the Local Bubble Using a Shadowing Filament in the Southern Galactic Hemisphere

We present an analysis of the X-ray spectrum of the Local Bubble, obtained by simultaneously analyzing spectra from two XMM-Newton pointings on and off an absorbing filament in the southern Galactic hemisphere (b ? -45?). We use the difference in the Galactic column density in these two directions to deduce the contributions of the unabsorbed foreground emission due to the Local Bubble, and the absorbed emission from the Galactic halo and the extragalactic background. We find the Local Bubble emission is consistent with emission from a plasma in collisional ionization equilibrium with a temperature log(TLB/K) = 6.06 and an emission measure ndl = 0.018 cm-6 pc. Our measured temperature is in good agreement with values obtained from ROSAT All-Sky Survey data, but is lower than that measured by other recent XMM-Newton observations of the Local Bubble, which find log(TLB/K) ? 6.2 (although for some of these observations it is possible that the foreground emission is contaminated by non-Local Bubble emission from Loop I). The higher temperature observed toward other directions is inconsistent with our data when combined with a FUSE measurement of the Galactic halo O VI intensity. This therefore suggests that the Local Bubble is thermally anisotropic. Our data are unable to rule out a nonequilibrium model in which the plasma is underionized. However, an overionized recombining plasma model, while observationally acceptable for certain densities and temperatures, generally gives an implausibly young age for the Local Bubble (6 ? 105 yr).
A NEW SOURCE OF METHYLENE MELDRUM'S ACID. REACTIONS WITH ENAMINES

ABSTRACT The unsymmetrical Knoevenagel–Michael product derived from Meldrum's acid, phenyl Meldrum's acid and formaldehyde was prepared as a pure, stable and crystalline product. This compound readily dissociates under the reaction conditions to produce methylene Meldrum's acid. This Knoevenagel–Michael product was used to explore a new application of methylene Meldrum's acid: the reaction with enamines.
Coverings of curves with asymptotically many rational points

Ihara defined the quantity A(q), which is the lim sup as g approaches ∞ of the ratio Nq(g)/g, where Nq(g) is the maximum number of rational points a curve of genus g defined over a finite field Fq may have. A(q) is of great relevance for applications to algebraic–geometric codes. It is known that A(q)⩽√q−1 and equality holds when q is a square. By constructing class field towers with good parameters, in this paper we present improvements of lower bounds of A(q) for q an odd power of a prime.
Spatial Evolution of the Dust-Acoustic Wave

Over the past twenty years, the dust-acoustic wave (DAW) has been a subject of intense study. In this paper, high-speed video imaging is employed to measure the evolution of wavefronts of a propagating DAW as it propagates through a weakly coupled dusty plasma system in an argon dc glow discharge plasma. In particular, measurements of the growth, saturation, and, then, damping of the wave mode as the wave propagates through the cloud are reported. It is observed that the wave amplitude initially exhibits rapid growth while the wavefront compresses. After this initial growth, the width of the wavefront remains relatively constant, while the amplitude of the wavefront evolves like the background dust medium. In some cases, it is also observed that the wave amplitude can decay more quickly than the background dust medium.
Electrophilic addition reactions of 1,1-difluoro-2,2-diphenylthioethylene

Abstract Electrophiles have been shown to add to F2CC(SPh)2 at the difluoromethylene carbon, indicating that sulfur is better able to stabilize a positive charge than fluorine.
Jets from jets: re-clustering as a tool for large radius jet reconstruction and grooming at the LHC

Jets with a large radius R ≳ 1 and grooming algorithms are widely used to fully capture the decay products of boosted heavy particles at the Large Hadron Collider (LHC). Unlike most discriminating variables used in such studies, the jet radius is usually not optimized for specific physics scenarios. This is because every jet configuration must be calibrated, insitu, to account for detector response and other experimental effects. One solution to enhance the availability of large-R jet configurations used by the LHC experiments is jet re-clustering. Jet re-clustering introduces an intermediate scale r < R at which jets are calibrated and used as the inputs to reconstruct large radius jets. In this paper we systematically study and propose new jet re-clustering configurations and show that re-clustered large radius jets have essentially the same jet mass performance as large radius groomed jets. Jet re-clustering has the benefit that no additional large-R calibration is necessary, allowing the re-clustered large radius parameter to be optimized in the context of specific precision measurements or searches for new physics.
Galaxy Kinematics with VIRUS-P: The Dark Matter Halo of M87

We present two-dimensional stellar kinematics of M87 out to R = 238'' taken with the integral field spectrograph VIRUS-P. We run a large set of axisymmetric, orbit-based dynamical models and find clear evidence for a massive dark matter halo. While a logarithmic parameterization for the dark matter halo is preferred, we do not constrain the dark matter scale radius for a Navarro-Frenk-White (NFW) profile and therefore cannot rule it out. Our best-fit logarithmic models return an enclosed dark matter fraction of 17.2+5.0 –5.0% within one effective radius (Re 100''), rising to 49.4+7.2 –8.8% within 2 Re . Existing SAURON data (R ≤13''), and globular cluster (GC) kinematic data covering 145'' ≤ R ≤ 554'' complete the kinematic coverage to R = 47 kpc (~5 Re ). At this radial distance, the logarithmic dark halo comprises 85.3+2.5 –2.4% of the total enclosed mass of 5.7+1.3 –0.9 × 1012 M ☉ making M87 one of the most massive galaxies in the local universe. Our best-fit logarithmic dynamical models return a stellar mass-to-light ratio (M/L) of 9.1+0.2 –0.2 (V band), a dark halo circular velocity of 800+75 –25 km s-1, and a dark halo scale radius of 36+7 –3 kpc. The stellar M/L, assuming an NFW dark halo, is well constrained to 8.20+0.05 –0.10 (V band). The stars in M87 are found to be radially anisotropic out to R 0.5 Re , then isotropic or slightly tangentially anisotropic to our last stellar data point at R = 2.4 Re where the anisotropy of the stars and GCs are in excellent agreement. The GCs then become radially anisotropic in the last two modeling bins at R = 3.4 Re and R = 4.8 Re . As one of the most massive galaxies in the local universe, constraints on both the mass distribution of M87 and anisotropy of its kinematic components strongly inform our theories of early-type galaxy formation and evolution in dense environments.
Legal change and the social value of lawsuits

This paper integrates the literatures on the social value of lawsuits, the evolution of the law, and judicial preferences to evaluate the hypothesis that the law evolves toward efficiency. The setting is a simple accident model with costly litigation where the efficient law minimizes the sum of accident plus litigation costs. The analysis shows that the law will not generally evolve completely toward any one rule, but will reach a steady state equilibrium in which the distribution of rules depends both on the selective litigation effect and the nature of judicial bias. The analysis also links legal change with the social value of lawsuits to allow an explicit evaluation of the lawmaking function of trials.
Coarsening in the two-dimensional soap froth and the large-Q Potts model: A detailed comparison

Abstract A detailed comparison between the experimental evolution of a two-dimensional soap froth and a next-nearest-neighbour Q = ∞ Potts model on a square lattice starting from identical initial conditions is presented. We compare the pattern evolution, dynamics, distribution functions and correlations of the two systems. We also examine in detail the relation between number or sides and area (Lewis' law) and two measures of pattern disorder. Overall agreement is found between the model and simulation, with a few systematic deviations which suggest that side redistribution is affected by subtle anisotropy and equilibration effects.
(t-Bu)2PN=P(i-BuNCH2CH2)3N : New Efficient Ligand for Palladium-Catalyzed C-N Couplings of Aryl and Heteroaryl Bromides and Chlorides and for Vinyl Bromides at Room Temperature

By employing Pd(OAc)2, Cs2CO3, or NaOH, and the new ligand (t-Bu)2PNP(i-BuNCH2CH2)3N (3a), an electronically diverse array of aryl bromides and chlorides possessing base-sensitive substituents (nitro, ester, and keto) provide coupling products with bulky aryl amines in good to excellent yields. Aryl halides possessing other functional groups including cyano, amino, trifluoromethyl, and phenol, coupled with equal ease, producing highly functionalized amines in good to excellent yields. Moreover, an aryl chloro group can be preserved in the presence of a bromo substituent under our reaction conditions. BOC-protected amines also participated efficiently. Heterocyclic bromides and chlorides underwent clean couplings with amines in excellent yields. An important strength of our protocol is the use of lower palladium loadings than those reported earlier, without compromising yields. The air-stable palladium complex (η3-cinnamyl)PdCl·(3a) (5) was also employed successfully in C−N coupling reactions while the cro...
Relaxation of wobbling asteroids and comets - theoretical problems, perspectives of experimental observation

Abstract A body dissipates energy when it freely rotates about any axis different from principal. This entails relaxation, i.e., decrease of the rotational energy, with the angular momentum preserved. The spin about the major-inertia axis corresponds to the minimal kinetic energy, for a fixed angular momentum. Thence one may expect comets and asteroids (as well as spacecraft or cosmic-dust granules) to stay in this, so-called principal, state of rotation, unless they are forced out of this state by a collision, or a tidal interaction, or cometary jetting, or by whatever other reason. As is well known, comet P/Halley, asteroid 4179 Toutatis, and some other small bodies exhibit very complex rotational motions attributed to these objects being in non-principal states of spin. Most probably, the asteroid and cometary wobble is quite a generic phenomenon. The theory of wobble with internal dissipation has not been fully developed as yet. In this article we demonstrate that in some spin states the effectiveness of the inelastic-dissipation process is several orders of magnitude higher than believed previously, and can be measured, by the presently available observational instruments, within approximately a year span. We also show that in some other spin states both the precession and precession-relaxation processes slow down considerably. (We call it near-separatrix lingering effect.) Such spin states may evolve so slowly that they can mimic the principal-rotation state.
Z-Selective, Mg-mediated synthesis of α,β-unsaturated-β-iodo Morita-Baylis-Hillman-type adducts

Abstract Morita–Baylis–Hillman-like tri- and tetra-substituted β-iodoalkene adducts can be efficiently synthesized from activated alkynes and aldehydes utilizing MgI2 in CH2Cl2 in excellent yields (65–96%, 16 examples) under mild reaction conditions. A variety of electronically diverse aldehydes react with several electron-deficient alkynes in this manner. The reactions proceed in 2–16 h room temperature or reflux. Furthermore, a trisubstituted Z-alkene was shown to thermodynamically isomerize upon exposure to MgI2 and heat to obtain the corresponding (E)-alkene adduct as the only observed stereoisomer.
Sleep disturbances after open heart surgery.

This study was designed to document quantitatively the sleep disturbances that occur after open heart surgery and to investigate a group of patients who underwent a thoracic surgical procedure not involving cardiopulmonary bypass. Nine patients were studied, six after open heart surgery and three after partial or complete pneumonectomy. In each patient, sleep patterns were recorded with use of all night polygraphy before and after operation and for up to 5 weeks on follow-up studies. After open heart surgery, patients manifested considerable suppression of electrophysiologic evidence of sleep as well as prolonged suppression of both rapid eye movement and slow wave sleep patterns. In the three patients subjected to thoracotomy these sleep indexes returned to preoperative levels much earlier. Evidence of stage 2 sleep was present in one of the three patients with thoracotomy on the first postoperative night, and in two of the three both rapid eye movement and slow wave sleep returned to preoperative levels by the time of hospital discharge. It is concluded that patients undergoing open heart surgery experience both acute and chronic disruptions of sleep that last well beyond the hospital period of convalescence. These sleep disturbances have considerable relevance for postoperative management.
A Jet Model with a Hard Electron Distribution for the Afterglow of GRB 000301c

The parameters of the gamma-ray burst (GRB) 000301c afterglow are determined within the usual framework of synchrotron emission from relativistic ejecta, through fits to the available radio-to-optical data. It is found that (1) the jet energy after the GRB phase is ~ 3 × 1050 ergs, (2) the initial opening angle of the jet is ~13°, (3) the medium that decelerates the afterglow has a density ~25 cm-3, (4) the power-law distribution of the shock-energized electrons is hard, with an index around 3/2, and (5) the cooling frequency was located below the optical domain. Furthermore, we find that the collimation of ejecta alone cannot explain the sharp and large magnitude break observed in the R-band emission of this afterglow at a few days, and that a high-energy break in the electron distribution, corresponding to an electron energy close to equipartition, together with the lateral spreading of the jet accommodate better this break. Microlensing by a star in an intervening galaxy produces only a flattening of the afterglow emission and cannot explain the mild brightening exhibited by the optical emission of 000301c at ~4 days.
Measurement of Refractive Index of Elastomers

Abstract The measurement of the refractive index of elastomers is discussed, with particular reference to GR-S rubber and the use of an Abbe type of refractometer. Detailed descriptions of the apparatus used and the procedure for GR-S rubber are given. Common sources of error are discussed and methods of minimizing these errors are given. A detailed stady has been made of the precision obtainable with GR-S polymers using the Abbe type of refractometer with an incandescent light source. It was found that the standard deviation corresponding to variability of a single random determination was 0.00007. The method has been used for several years as the basis for the determination of bound styrene in copolymers of butadiene and styrene, and is currently employed for control purposes in the government-owned synthetic rubber plants. It has also been used for determining the percentage of rubber hydrocarbon in natural rubber and for locating second-order transition temperatures.
Why are solitons stable

The theory of linear dispersive equations predicts that waves should spread out and disperse over time. However, it is a remarkable phenomenon, observed both in theory and practice, that once nonlinear effects are taken into account, \emph{solitary wave} or \emph{soliton} solutions can be created, which can be stable enough to persist indefinitely. The construction of such solutions is relatively straightforward, but the fact that they are \emph{stable} requires some significant amounts of analysis to establish, in part due to symmetries in the equation (such as translation invariance) which create degeneracy in the stability analysis. The theory is particularly difficult in the \emph{critical} case in which the nonlinearity is at exactly the right power to potentially allow for a self-similar blowup. In this article we survey some of the highlights of this theory, from the more classical orbital stability analysis of Weinstein and Grillakis-Shatah-Strauss, to the more recent asymptotic stability and blowup analysis of Martel-Merle and Merle-Raphael, as well as current developments in using this theory to rigorously demonstrate controlled blowup for several key equations.