cssi/SciSciGPT-SciSciNet huggingface dataset:
Turbulence In The Solar Atmosphere: Manifestations And Diagnostics Via Solar Image Processing

Intermittent magnetohydrodynamical turbulence is most likely at work in the magnetized solar atmosphere. As a result, an array of scaling and multi-scaling image-processing techniques can be used to measure the expected self-organization of solar magnetic fields. While these techniques advance our understanding of the physical system at work, it is unclear whether they can be used to predict solar eruptions, thus obtaining a practical significance for space weather. We address part of this problem by focusing on solar active regions and by investigating the usefulness of scaling and multi-scaling image-processing techniques in solar flare prediction. Since solar flares exhibit spatial and temporal intermittency, we suggest that they are the products of instabilities subject to a critical threshold in a turbulent magnetic configuration. The identification of this threshold in scaling and multi-scaling spectra would then contribute meaningfully to the prediction of solar flares. We find that the fractal dimension of solar magnetic fields and their multi-fractal spectrum of generalized correlation dimensions do not have significant predictive ability. The respective multi-fractal structure functions and their inertial-range scaling exponents, however, probably provide some statistical distinguishing features between flaring and non-flaring active regions. More importantly, the temporal evolution of the above scaling exponents in flaring active regions probably shows a distinct behavior starting a few hours prior to a flare and therefore this temporal behavior may be practically useful in flare prediction. The results of this study need to be validated by more comprehensive works over a large number of solar active regions. Sufficient statistics may also establish critical thresholds in the values of the multi-fractal structure functions and/or their scaling exponents above which a flare may be predicted with a high level of confidence.
A High-Resolution Mosaic of Molecular Gas in Stephan's Quintet

We present high-resolution 12CO J = 1-0 observations of the molecular gas in the Hickson compact group Stephan's Quintet (HCG 92). Our observations consist of multiple pointings and mosaics covering all the regions where CO and star formation have been detected. Within the 100'' field of view centered on the easternmost tidal tail, we detect three clumps of emission that may be partially resolved at our resolution of 8''; two of these are new detections not previously seen in ISM studies of this region. Two of these clumps lie in the optical tidal tail, while the third lies to the southeast and is coincident with a large H I feature, but it does not correspond to any features at other wavelengths. We also tentatively detect CO emission from the star-forming regions in the "old tail" corresponding to recent star formation activity detected in recent UV and Hα observations. Observations of the rest of the compact group do not show detections, even though strong emission was detected with single-dish telescopes, which suggests that the CO emission originates from a diffuse molecular gas cloud or from at least three separate clumps with separations greater than around 3 kpc.
Decisions, decisions: Noise and its effects on integral Monte Carlo algorithms

Abstract In the present Letter, we examine the effects of noise on Monte Carlo algorithms, a problem raised previously by Kennedy and Kuti (Phys. Rev. Letters 54 (1985) 2473). We show that the effects of introducing unbiased noise into the acceptance/rejection phase of the conventional Metropolis approach are surprisingly modest, and, to a significant degree, largely controllable. We present model condensed phase numerical applications to support these conclusions.
Makespan minimization in online scheduling with machine eligibility

In this paper we provide a survey of online scheduling in parallel machine environments with machine eligibility constraints and the makespan as objective function. We first give a brief overview of the different parallel machine environments and then survey the various types of machine eligibility constraints, including tree-hierarchical processing sets, Grade of Service processing sets, interval processing sets, and nested processing sets. We furthermore describe the relationships between the various different types of processing sets. We proceed with describing two basic online scheduling paradigms, namely online over list and online over time. For each one of the two paradigms we survey all the results that have been recorded in the literature with regard to each type of machine eligibility constraints. We obtain also several extensions in various directions. In the concluding section we describe the most important open problems in this particular area.
THE SINE-GORDON EQUATION IN THE SEMICLASSICAL LIMIT: CRITICAL BEHAVIOR NEAR A SEPARATRIX

We study the Cauchy problem for the sine-Gordon equation in the semiclassical limit with pure-impulse initial data of sufficient strength to generate both high-frequency rotational motion near the peak of the impulse profile and also high-frequency librational motion in the tails. Subject to suitable conditions of a general nature, we analyze the fluxon condensate solution approximating the given initial data for small time near points where the initial data crosses the separatrix of the phase portrait of the simple pendulum. We show that the solution is locally constructed as a universal curvilinear grid of superluminal kinks and grazing collisions thereof, with the grid curves being determined from rational solutions of the Painleve-II system.
Revisiting the Role of M31 in the Dynamical History of the Magellanic Clouds

We study the dynamics of the Magellanic Clouds in a model for the Local Group whose mass is constrained using the timing argument/two-body limit of the action principle. The goal is to evaluate the role of M31 in generating the high angular momentum orbit of the Clouds, a puzzle that has only been exacerbated by the latest Hubble Space Telescope proper motion measurements. We study the effects of varying the total Local Group mass, the relative mass of the Milky Way (MW) and M31, the proper motion of M31, and the proper motion of the Large Magellanic Cloud (LMC) on this problem. Over a large part of this parameter space, we find that tides from M31 are insignificant. For a range of LMC proper motions approximately 3σ higher than the mean and total Local Group mass >3.5 × 1012 M ☉, M31 can provide a significant torque to the LMC orbit. However, if the LMC is bound to the MW, then M31 is found to have negligible effect on its motion, and the origin of the high angular momentum of the system remains a puzzle. Finally, we use the timing argument to calculate the total mass of the MW-LMC system based on the assumption that they are encountering each other for the first time, their previous perigalacticon being a Hubble time ago, obtaining M MW + M LMC = (8.7 ± 0.8) × 1011 M ☉.
Geometry of N = 1 super Yang-Mills theory in curved superspace

We give a new description of N=1 super Yang-Mills theory in curved superspace. It is based on the induced geometry approach to a curved superspace in which it is viewed as a surface embedded into C 4|2 . The complex structure on C 4|2 supplied with a standard volume element induces a special Cauchy-Riemann (SCR)-structure on the embedded surface. We give an explicit construction of SYM theory in terms of intrinsic geometry of the superspace defined by this SCR-structure and a CR-bundle over the superspace. We write a manifestly SCR-covariant Lagrangian for SYM coupled with matter. We also show that in a special gauge our formulation coincides with the standard one which uses Lorentz connections. Some useful auxiliary results about the integration over surfaces in superspace are obtained.
How to forget the past without repeating it

Bottom-up evaluation of deductive database programs has the advantage that it avoids repeated computations by storing all intermediate results and replacing recomputation by table lookup. However, in general, storing all intermediate results for the duration of a computation wastes space. In this paper, we propose an evaluation scheme that avoids recomputation, yet for a fairly general class of programs at any given time stores only a small subset of the facts generated. The results constitute a significant first step in compile-time garbage collection for bottom-up evaluation of deductive database programs.
Phase Stability in Binary Ti-Al

Binary Ti-Al samples containing from 46 to 54 at.% Al were solidified while undercooled by various amounts using electromagnetic levitation techniques. A detailed thermal history of these samples was obtained with sampling rates as high as 500 KHz during recalescence. This very high sampling rate was essential to resolve the thermal events. Primary α solidification was observed in samples containing from 51 to 54 at.% Al. that were undercooled less than about 100 K at solidification. Primary {tiβ} solidification was found for all undercoolings tested in samples containing less than 51 at.% Al and for undercoolings greater than about 100 K in samples containing 51 to 54 at.% Al. These first two observations are in agreement with results from Valencia et al. for Ti-45 at.% Al and Ti-50 at.% Al, respectively [4]. However, the third observation of {tiβ} as the primary solidification structure at high undercooling and 54 at.% Al differs from Valencia's interpretation for Ti-55 at.% Al. The results in this study are conistent with the proposed McCullough Ti-Al phase diagram.
Cosmological hydrodynamics with multi-species chemistry and nonequilibrium ionization and cooling

Abstract We have developed a method of solving for multi-species chemical reaction flows in nonequilibrium and self-consistently with the hydrodynamic equations in an expanding FLRW universe. The method is based on a backward differencing scheme for the required stability when solving stiff sets of equations and is designed to be efficient for three-dimensional calculations without sacrificing accuracy. In all, 28 kinetic reactions are solved including both collisional and radiative processes for the following nine separate species: H, H + , He, He + , He ++ , H − , H 2 + , H 2 , and e − . The method identifies those reactions (involving H − and H 2 + ) occurring on the shortest time scales, decoupling them from the rest of the network and imposing equilibrium concentrations to good accuracy over typical cosmological dynamical times. Several tests of our code are presented, including radiative shock waves, cosmological sheets, conservation constraints, and fully three-dimensional simulations of CDM cosmological evolutions in which we compare our method to results obtained when the packaged routine LSODAR is substituted for our algorithms.
Is the doubler of the electron an antiquark

Abstract Reassigning degrees of freedom in the standard model allows an interpretation where the SU(2) gauge group is vector-like and parity violation moves to the strong and electromagnetic interactions. In this picture, the electron is paired with an anti-quark. Requiring exact gauge invariance for the electromagnetic interaction clarifies the mechanism behind a recent proposal for a lattice regularization of the standard model.
Modeling the high-speed switching of far-infrared radiation by photoionization in a semiconductor

Data from an earlier study [T. Vogel et al., Appl. Opt. 31, 329 (1992)] on the subnanosecond switching of $119\ensuremath{-}\ensuremath{\mu}\mathrm{m}$ radiation in high-resistivity silicon by pulsed UV laser radiation, is compared with a refined one-dimensional numerical multilayer model accounting for the generation, recombination, and diffusion of the free carriers on the resulting far-infrared optical properties of the silicon. The inclusion of recent measurements for carrier-density and temperature-dependent transport parameters leads to improved agreement between experiment and theory.
Kinematics of Molecular Hydrogen Emission from Pre-Planetary Nebulae: RAFGL 2688 and RAFGL 618

We present high spectral resolution maps of near-infrared molecular hydrogen emission from the bipolar pre-planetary nebulae RAFGL 2688 and RAFGL 618, obtained with the NOAO Phoenix spectrometer. The measured velocity gradients along the polar axes of both nebulae indicate that the highest velocity gas lies closest to the central stars. These results support the suggestion that the polar H2 emission regions of both nebulae contain shocked gas formed as fast (~50-150 km s-1), collimated, post-asymptotic giant branch (AGB) winds collide with slower moving (~10-20 km s-1) material previously ejected while the central stars were still on the AGB. The kinematics of H2 emission perpendicular to the polar axis of RAFGL 2688 are consistent with a model combining expansion along the equator at 5-10 km s-1 with rotation about the polar axis at 5-10 km s-1. The rapid onset of the common envelope phase of a close binary system may explain both the bipolar structure of RAFGL 2688 and the presence and complex kinematics of its shocked H2 emission.
Light rare earth elements and natural series radionuclides within the Morro do Ferro

As part of the Pocos de Caldas natural analogue project, data are presented on natural series radionuclides (232Th, 230Th, 228Th, 234U, 238U and 231Pa) and the light rare earth elements (LREEs) La, Ce, Pr, Nd and Sm from two boreholes within the near surface thorium-rare earth element ore body known as Morro do Ferro (MF). Under defined conditions, a study of these elements can provide useful information on the long term behavior of chemical analogues present in high level waste (HLW) and on the processes affecting radionuclide migration. Within the deeply weathered mineralized zone, Th decreases exponentially with a half thickness of 10 meters from 5.7% in the surface meter to 0.1% at 36 meters. Since no fractionation of 228Ra is evident (based on 228Th232Th equilibrium), 228Ra is essentially decaying in-situ where it is radiogenically produced. Uranium isotopes (mean = 35 ppm as 238U) are found in near equilibrium (234U/238U range of 0.9 to 1.1) both within the mineralization and down along the hydraulic gradient. No evidence for any significant uranium accumulation exists. Leaching of uranium by infiltrating, oxidizing rain water is postulated as the dominant removal mechanism although preferential loss of 234U also occurs as evidenced by 234U/238U ratios of < 1.0 in rock and between 1.1 and 1.5 in ground water samples. Positive and negative Ce anomalies are reported and have been interpreted as occurring from relic redox fronts which are no longer visible.
Olefin Hydroaryloxylation Catalyzed by Pincer–Iridium Complexes

Aryl alkyl ethers, which are widely used throughout the chemical industry, are typically produced via the Williamson ether synthesis. Olefin hydroaryloxylation potentially offers a much more atom-economical alternative. Known acidic catalysts for hydroaryloxylation, however, afford very poor selectivity. We report the organometallic-catalyzed intermolecular hydroaryloxylation of unactivated olefins by iridium “pincer” complexes. These catalysts do not operate via the hidden Bronsted acid pathway common to previously developed transition-metal-based catalysts. The reaction is proposed to proceed via olefin insertion into an iridium–alkoxide bond, followed by rate-determining C–H reductive elimination to yield the ether product. The reaction is highly chemo- and regioselective and offers a new approach to the atom-economical synthesis of industrially important ethers and, potentially, a wide range of other oxygenates.
Influence of solar sector boundaries on ionospheric variability

A latitudinal network of total electron content (TEC) observations has been used to assess the contributions to day-to-day F region variability associated with a wide variety of solar-terrestrial phenomena. Recent discussions of a proposed “sun-weather coupling” effect related to solar wind sector boundary (SB) crossings prompted a systematic search to document any upper atmospheric components of such a linkage. TEC data from several North American sites close to the 70°W meridian (Narssarssuaq, Greenland (L = 5); Goose Bay, Labrador (L = 4); Sagamore Hill, Massachusetts (L = 3); and the Kennedy Space Center, Florida (L = 2) were examined during the years 1973–1975. Average daytime (0900–1700 LT) TEC values were compared with a 27-day mean centered on the day of an SB crossing. The resultant percentage deviations were examined for sector polarity (plus to minus versus minus to plus) effects and for overall latitudinal patterns during a period of ±5 days from the SB crossings. Average results for the entire data set show peak excursions well within the ±20–25% deviations associated with day-to-day variability. There is, however, a remarkable consistency in the coherence of the small amplitude latitudinal patterns. At middle to high latitudes (L = 3–5), the TEC variations show an ordered transition from enhancements to depletions following an SB crossing. At lower latitudes (L = 2), the opposite pattern of depletions to enhancements occurs. An identical analysis for geomagnetic activity variations (using the planetary index Ap) reveals the well-known pattern of a transition from relatively quiet to relatively disturbed activity as a sector is crossed. A merging of these two results suggests that the manifestation in the F region of SB crossings is nothing more than a small-scale version of the average “geomagnetic/ionospheric storm effect” that is well documented over the L = 2–5 range. The latitudinal patterns for ΔTEC, and their seasonal variations, are consistent with the morphology of O/N2 variations during geomagnetic disturbances and southward IMF effects during equinoctial versus solstice periods.
Determination of Goslarite–Bianchite Equilibria by the Humidity-Buffer Technique at 0.1 MPa

Goslarite–bianchite equilibria were determined along four humidity-buffer curves at 0.1 MPa and between 27 and 36 °C. Results, based on tight reversals along each humidity buffer, can be represented by ln K (±0.005)=19.643−7015.38/T, where K is the equilibrium constant and T is temperature in K. Our data are in excellent agreement with several previous vapor-pressure measurements and are consistent with the solubility data reported in the literature. Thermodynamic analysis of these data yields 9.634 (±0.056) kJ mol−1 for the standard Gibbs free energy of reaction, which is in good agreement with the value of 9.658 kJ mol−1 calculated from the thermodynamic data compiled and evaluated by Wagman et al. [Wagman, D.D., Evans, W.H., Parker, V.B., Schumm, R.H., Halow. I., Bailey, S.M., Churney, K.L., Nuttal, R.L., 1982. The NBS tables of chemical thermodynamic properties. Selected values for inorganic and C1 and C2 organic substances in SI units. J. Phys. Chem. Ref. Data 11, Suppl. 2].
Economic Feasibility of Diesel Fuel Substitutes from Oilseeds in New York State

Abstract The feasibility of producing oilseeds for feed and for diesel fuel substitute has primarily been discussed in terms of the major oilseed producing areas. The Northeast region of the United States is a major agricultural producing area which imports large quantities of soybean meal for cattle feed. This paper considers the technical economic feasibility of producing oilseeds for feed and fuel in New York State, which is selected as a case study for the region. The possible crops considered for expanded production are sunflowers, soybeans, and flax. It is found that if enough oilseeds are grown to replace 25% of the diesel fuel used on farms, then at most 5% of the cropland would have to be converted to oilseeds, and meal would not be produced in excess of the amount currently used. The cost of producing oil is calculated as the cost of producing the seed plus the cost of processing minus the value of the meal. Enterprise budgets are developed for estimating oilseed production costs in New York State. The cost of processing is estimated for both an industrial-size plant, which does not now exist in New York, and a small on-farm plant. It is found that the diesel fuel and vegetable oil prices would have to rise substantially before oilseeds were produced in the Northeast region for feed and fuel. Moreover, the construction of an oilseed processing facility would not necessarily stimulate production of oilseeds in the region.
Aerodynamic Interference Between Two Darrieus Wind Turbines

The effect of aerodynamic interference on the performance of two curved bladed Darrieus-type vertical axis wind turbines has been calculated using a vortex/lifting line aerodynamic model. The turbines have a tower-to-tower separation distance of 1.5 turbine diameters, with the line of turbine centers varying with respect to the ambient wind direction. The effects of freestream turbulence were neglected. For the cases examined, the calculations showed that the downwind turbine power decrement (1) was significant only when the line of turbine centers was coincident with the ambient wind direction, (2) increased with increasing tipspeed ratio, and (3) is due more to induced flow angularities downstream than to speed deficits near the downstream turbine.
Investor efficiency in the face of takings

Governmental entities at all levels are empowered to acquire private property for the public's benefit, provided that “just compensation” is paid. The level of compensation typically viewed by courts as “just” is market value, but questions arise as to whether market value compensation motivates the private owner of land, potentially subject to a taking, to improve the property to a degree that is socially efficient. Earlier works have found market value to be a compensation level too high to promote efficiency. The present paper offers an analysis, based on a simple model of investor profit maximization, that provides a unified view of models presented in some important earlier works. In a special application of the general case, it is shown that market value can be too low a level of compensation to promote efficient behavior by the land owner.
Automatically Proving Concurrent Programs Correct

Summary form only given. This talk describes new advances that allow us to automatically prove both liveness properties and heap-shape properties of concurrent programs. The talk focuses on recent thread-modular extensions to the program termination prover TERMINATOR and shape analysis tool SLAyer and their application to Windows device drivers.
Evidence for quenched chiral logs

Abstract Using the pole shifting procedure of the modified quenched approximation (MQA) to cure the exceptional configuration problem, accurate hadron spectrum calculations can be obtained at very light quark mass. Here we use the MQA to extend and improve our previous investigation of chiral logs in the pion mass. At β = 5.7 for Wilson fermions, we see clear evidence for quenched chiral logarithms in the pion mass as a function of quark mass. The size of the observed chiral log exponent δ is in good agreement with the value obtained from a direct calculation of the η′ hairpin diagram.
Strings in less than one dimension and the generalized KdV hierarchies

We find the differential equation satisfied by the exact specific heat for a series of models of matter coupled to 2D gravity, indexed by positive integers p and q, and present evidence that they are the c<1 minimal models with diagonal modular invariants.
Beyond Spacetime Geometry—The Death of Philosophy and Its Quantum Reincarnation

Contrary to the “end” and “death” assertions on philosophy, this paper predicts an equilibrium-based and harmony-centered scientific reincarnation of philosophy. Logically, the reincarnation is backed by a formal system and a background independent geometry that transcends spacetime. Physically, it is supported by definable quantum causality and bipolar logical unifications of matter and antimatter, particle and wave, big bang and black hole, relativity and quantum entanglement. Philosophically, it is distinguished from Western metaphysics and dialectics as well as the Dao of Laozi. It is named a quantum reincarnation for its central claim that YinYang bipolar quantum entanglement is the source of causality for the Being of beings following the 2nd law of thermodynamics. Thus, it presents a modest unification of science and philosophy for their reciprocal interaction (Note: Equilibrium subsumes non-equilibrium and quasi—equilibrium as local non-equilibriums can form global equilibrium or quasi-equilibrium).
A Versatile Acceleration-Based Cam Profile for Single-Dwell Applications Requiring Cam-Follower Clearance During Dwell

Presented in this paper is a cam motion program suitable for single-dwell cam-follower systems with built-in clearance between the cam and follower during the dwell portion of the cycle. This makes the motion program particularly well-suited to applications such as valve trains in internal combustion engines in which cam-follower clearance is necessary to ensure proper seating of a poppet valve, preventing gas leakage across the seal. The motion program for the cam follower is derived from the follower acceleration function so that designers can control the ratio of the magnitudes of positive and negative accelerations. This provides cam designers more control over the cam-follower interface force and therefore more control over factors such as cam wear and the potentially destructive phenomenon known as “follower jump.” Included in the motion program is asymmetric rise and fall that allows different times for these events. The follower acceleration is designed to be smooth enough to provide continuous jerk throughout the actuation phase, thereby tending to reduce undesirable residual vibrations. The motion program used to close and open the clearance gap is derived from a velocity function, allowing more control of follower inertia during the important clearance closing event. The motion program is presented in a form appropriate for implementation in standard engineering equation-solving software, giving the cam designer easy control over important parameters in high-speed cam-follower systems.Copyright © 2011 by ASME
VXA: a virtual architecture for durable compressed archives

Data compression algorithms change frequently, and obsolete decoders do not always run on new hardware and operating systems, threatening the long-term usability of content archived using those algorithms. Re-encoding content into new formats is cumbersome, and highly undesirable when lossy compression is involved. Processor architectures, in contrast, have remained comparatively stable over recent decades. VXA, an archival storage system designed around this observation, archives executable decoders along with the encoded content it stores. VXA decoders run in a specialized virtual machine that implements an OS-independent execution environment based on the standard x86 architecture. The VXA virtual machine strictly limits access to host system services, making decoders safe to run even if an archive contains malicious code. VXA's adoption of a "native" processor architecture instead of type-safe language technology allows reuse of existing "hand-optimized" decoders in C and assembly language, and permits decoders access to performance-enhancing architecture features such as vector processing instructions. The performance cost of VXA's virtualization is typically less than 15% compared with the same decoders running natively. The storage cost of archived decoders, typically 30-130KB each, can be amortized across many archived files sharing the same compression method.
Main-group elements as transition metals

The chemistry of heavier main-group elements such as aluminium, silicon and phosphorus is very different from that of the lighter ones such as boron, carbon and nitrogen, yet discussions of this topic have been dominated by comparisons with the light elements. Philip Power's review focuses on advances in chemistry of the heavier main-group elements that reveal them as having more in common with the transition metals than the lighter members of the main groups. The concept of heavier main-group elements as 'transition metals' is supported by recent work showing that many of the new compounds react with small molecules such as H2, NH3, C2H4 and CO under mild conditions and display potential as catalysts. The last quarter of the twentieth century and the beginning decade of the twenty-first witnessed spectacular discoveries in the chemistry of the heavier main-group elements. The new compounds that were synthesized highlighted the fundamental differences between their electronic properties and those of the lighter elements to a degree that was not previously apparent. This has led to new structural and bonding insights as well as a gradually increasing realization that the chemistry of the heavier main-group elements more resembles that of transition-metal complexes than that of their lighter main-group congeners. The similarity is underlined by recent work, which has shown that many of the new compounds react with small molecules such as H2, NH3, C2H4 or CO under mild conditions and display potential for applications in catalysis.
Development Policies in the EU: An International Comparison

This paper studies the impact of the EU Structural Funds Program for the period 1989–93 on the growth paths of the major recipient countries, Greece, Ireland, and Portugal. It uses an endogenous growth model of private, public, and human capital accumulation in which the public sector and current account balances play a crucial role. Simulation results show that these programs had a substantial impact on economic growth in these economies and contributed markedly to their convergence to EU standards. Their relative long-run position, however, would still be far from EU standards, which suggests the importance of continuing the transfer program.
Fatigue performance of a bonded wavy composite lap joint

A novel wavy lap joint design was further studied. Our previous studies using cross-ply composite adherends showed that the new design was indeed much stronger than the conventional flat joint. In order to fully demonstrate advantage of the new wavy lap joint over the conventional single lap joint, comparative fatigue tests were performed to determine the durability performance of the wavy joint. In this study, a comparative static strength test of the conventional flat joint and the wavy joint was first carried out using unidirectional composite adherends. Then fatigue tests at different load levels and load frequencies were conducted. The test results showed that the wavy lap joint had a much longer fatigue life than the conventional lap joint.
An anisotropic mesh parameterization scheme

We introduce a simple anisotropic modification of Floater’s shape-preserving parameterization scheme. The original scheme is formulated as a discrete energy minimization and the modification is performed by introducing an additional stretching term. Results and example applications to anisotropic regular surface meshing are presented.
VLF Pulse Timing: Limitations and Potential as a Companion to Omega

The potential accuracy of VLF pulse (envelope) timing is severely limited by vagaries of the propagation medium and atmospheric noise due to spherics. These limitations are discussed in depth. The conclusion is that VLF pulse-timing accuracy corresponding to about 5 n.mi. should be possible over very long ranges up to 5000 n.mi. A hypothetical system employing pulse transmitters co-located at the Omega sites is explored. It is proposed that such a pulse system and the present phase–only Omega system could serve to complement each other as a coarse–fine system.
The general (2,2) gauged sigma model with three-form flux

We find the conditions under which a Riemannian manifold equipped with a closed three-form and a vector field define an on-shell = (2, 2) supersymmetric gauged sigma model. The conditions are that the manifold admits a twisted generalized Kahler structure, that the vector field preserves this structure, and that a so-called generalized moment map exists for it. By a theorem in generalized complex geometry, these conditions imply that the quotient is again a twisted generalized Kahler manifold; this is in perfect agreement with expectations from the renormalization group flow. This method can produce new = (2, 2) models with NS flux, extending the usual Kahler quotient construction based on Kahler gauged sigma models.
Finite multi-coset sampling and sparse arrays

Signals with sparse but otherwise unknown frequency content are well-represented by multi-coset samples, and efficient algorithms can be used to recover the underlying sparsity structure. While such sampling is usually analyzed over a sampling interval sufficiently large that edge effects can be ignored, in this work we develop how to take into account finite-window effects in system design. Such considerations are particularly important in the context of antenna arrays, and we analyze the associated redundancy. Additionally, we describe an efficient MIMO radar implementation of multi-coset arrays. As an example application of our results, we develop a natural two-stage architecture for direction-of-arrival estimation in sparse environments using a multi-coset array over the available aperture.
Luxury suites and team selling in professional sport

Purpose – The purpose of this paper is to provide a framework for team selling to sports firms that can be used to more effectively select members for sales and CRM teams and improve the performance of teams in attracting and retaining premium seating customers.Design/methodology/approach – The paper provides a two‐stage framework based on the personal selling process and the activities that support CRM programs. Recommendations are guided by the sport marketing and team selling literature streams and by best practices in sport marketing.Findings – The paper recommends the formation of two teams (personal selling and CRM) during the customer relationship cycle and provides guidelines for team member selection based on the critical activities that occur during the personal selling and CRM processes. Key success factors are provided, including the establishment of a customer‐focused organization and effective communication practices among team members and between selling teams.Originality/value – Although t...
Separated nets in Euclidean space and Jacobians of biLipschitz maps

We show that there are separated nets in the Euclidean plane which are not biLipschitz equivalent to the integer lattice. The argument is based on the construction of a continuous function which is not the Jacobian of a biLipschitz map.
The Galilean satellites as a source of CO in the Jovian upper atmosphere

Material from the Galilean satellites of Jupiter ejected by energetic particles in the Jovian magnetosphere may provide large sources of oxygen to the parent planet. Formation of a CO molecule is the ultimate fate of an oxygen atom in the upper Jovian atmosphere. This high altitude source of CO supports Beer and Taylor's (1978, Astrophys. J. 221) observations and analysis, provided that the globally averaged O atom input flux is ∼10^7 cm^(−2) sec^(−1) and the eddy diffusion coefficient at the tropopause is ∼10^3 cm^2 sec^(−1). Implications for the possible presence of other atoms and molecules derived from the satellites are discussed.
Shapes and Shears, Stars and Smears: Optimal Measurements for Weak Lensing

We present the theoretical and analytical bases of optimal techniques to measure weak gravitational shear from images of galaxies. We first characterize the geometric space of shears and ellipticity and then use this geometric interpretation to analyze images. The steps of this analysis include measurement of object shapes on images, combining measurements of a given galaxy on different images, estimating the underlying shear from an ensemble of galaxy shapes, and compensating for the systematic effects of image distortion, bias from point-spread function (PSF) asymmetries, and "dilution" of the signal by the seeing. These methods minimize the ellipticity measurement noise, provide calculable shear uncertainty estimates, and allow removal of systematic contamination by PSF effects to arbitrary precision. Galaxy images and PSFs are expressed as "Laguerre expansions," a two-dimensional generalization of the Edgeworth expansion, making the PSF correction and shape measurement relatively straightforward and computationally efficient. We also discuss sources of noise-induced bias in weak-lensing measurements—selection biases, and "centroid" biases arising from noise rectification—and provide a solution for these and previously identified biases.
Multi-center electronic structure calculations for plasma equation of state

Abstract We report on an approach for computing electronic structure utilizing solid-state multi-center scattering techniques, but generalized to finite temperatures to model plasmas. This approach has the advantage of handling mixtures at a fundamental level without the imposition of ad-hoc continuum lowering models, and incorporates bonding and charge exchange, as well as multi-center effects in the calculation of the continuum density of states.
Multi-chord fiber-coupled interferometer with a long coherence length laser

This paper describes a 561 nm laser heterodyne interferometer that provides time-resolved measurements of line-integrated plasma electron density within the range of 1015−1018 cm−2. Such plasmas are produced by railguns on the plasma liner experiment, which aims to produce μs-, cm-, and Mbar-scale plasmas through the merging of 30 plasma jets in a spherically convergent geometry. A long coherence length, 320 mW laser allows for a strong, sub-fringe phase-shift signal without the need for closely matched probe and reference path lengths. Thus, only one reference path is required for all eight probe paths, and an individual probe chord can be altered without altering the reference or other probe path lengths. Fiber-optic decoupling of the probe chord optics on the vacuum chamber from the rest of the system allows the probe paths to be easily altered to focus on different spatial regions of the plasma. We demonstrate that sub-fringe resolution capability allows the interferometer to operate down to line-integrated densities of the order of 5 × 1015 cm−2.
Identifying Control Motives in Managerial Ownership: Evidence from Antitakeover Legislation

This study uses the introduction of second-generation antitakeover legislation as a natural experimental setting to infer the value that managers place on the control rights conferred by stock ownership. We conjecture that managers will reduce their stockholdings in the post-legislation period because they can ensure their prior level of control while holding fewer risky shares. Using a variety of specifications, we find robust evidence consistent with this "revealed preference" hypothesis. Further demonstrating the key role played by control considerations in managers' stockholding decisions, the reductions in ownership are concentrated in management teams with higher levels of initial ownership and in firms without poison pills.
Impacts of Road-Trains on the Geometric Design of Highways

AbstractFor enhanced efficiency and sustainability, transportation must rely on new technologies. Researchers and engineers work nowadays on many valuable and green transportation ideas. One such idea creates vehicle platoons on freeways to achieve multiple benefits: reductions in gas consumption, vehicle emissions, and traffic congestion through enhanced aerodynamics and road space utilization, as well as improvements in safety and driver comfort through fail-safe mechanisms and moderation of collision damages given similar vehicle speed. The technological enhancements are built into the vehicles. The existing freeway infrastructures do not necessitate modification. Still, the interactions between the human factors, or lack thereof, and the new technologies may directly impact the traditional guidelines for freeway design. Over time, the dedicated freeways of the future, whether rehabilitated or built anew, could satisfy guidelines derived specifically for road-trains. Further, freeways built to current ...
Square meshes are not always optimal

Mesh-connected computers with multiple buses providing broadcast facilities along rows and columns are discussed. A tight bound of Theta (n/sup 1/8/) is established for the number of rounds required for semigroup computations on n values distributed on a two-dimensional rectangular mesh of size n with a bus on every row and column. The upper bound is obtained for a skewed rectangular mesh of dimensions n/sup 3/8/*n/sup 5/8/. This result is compared to the tight bound of Theta (n/sup 1/6/) for the same problem on the square (n/sup 1/2/*n/sup 1/2/) mesh. It is shown that in the presence of multiple buses, a skewed configuration may perform better than a square configuration for certain computational tasks. The result can be extended to the d-dimensional mesh, giving a lower bound of Omega (n/sup 1/d alpha /) and an upper bound of O(d2/sup d+1/ n/sup 1/d alpha /), where alpha =2/sup d/; these bounds are optimal within constant factors for any constant d. It is noted that for d>3, the results of are mostly of theoretical interest. >
Correlations between zeros of a random polynomial

We obtain exact analytical expressions for correlations between real zeros of the Kac random polynomial. We show that the zeros in the interval (−1, 1) are asymptotically independent of the zeros outside of this interval, and that the straightened zeros have the same limit-translation-invariant correlations. Then we calculate the correlations between the straightened zeros of theO(1) random polynomial.
The K-theory of the flag variety and the Fomin–Kirillov quadratic algebra

Abstract We propose a new approach to the multiplication of Schubert classes in the K-theory of the flag variety. This extends the work of Fomin and Kirillov in the cohomology case, and is based on the quadratic algebra defined by them. More precisely, we define K-theoretic versions of the Dunkl elements considered by Fomin and Kirillov, show that they commute, and use them to describe the structure constants of the K-theory of the flag variety with respect to its basis of Schubert classes.
Subgame perfect equilibrium with continuous reaction functions

Abstract Earlier efforts by Friedman examined infinite horizon oligopolies trying (and failing) to show existence of subgame perfect Nash equilibria with the firms' strategies being continuous reaction functions. Here, in a typical game theoretic model with discounting, we prove the existence of such equilibria. The equilibrium strategies mimic trigger strategies in their method of operation but are continuous, so that small defections from equilibrium actions result in small (per period) punishments. We prove our results by constructing equilibria in a fashion analogous to that found in proofs of Folk Theorems in repeated games.
Magnetic island effects on axisymmetric equilibria

The plasma magnetohydrodynamics equilibrium equation in the vicinity of a single, thin magnetic island region is derived. First, the pressure profile in the vicinity of an island is determined using the continuity of transport fluxes across the island assuming a diffusive form for the fluxes. Then, by considering the island-induced magnetic perturbation, the structure of the current density around an island is examined. The modifications of the pressure and current density in the vicinity of a magnetic island lead to an equation that describes the toroidal equilibrium of the plasma. An “effective” axisymmetric Grad–Shafranov equation is constructed by taking a helical average over the toroidal equilibrium. Thus, we can take account of the three-dimensional magnetic island effects for a thin island in a two-dimensional equation. As with the Grad–Shafranov equation, the calculation does not employ a large aspect ratio or small β approximation; however, it uses a small island width (w≪r)s expansion. Finally,...
A comparison of the potential acuity meter (PAM) and the illuminated near card (INC) in patients undergoing phacoemulsification.

A comparison of the potential acuity meter (PAM) and the illuminated near card (INC) in patients undergoing phacoemulsification
The Computational Hardness of Counting in Two-Spin Models on d-Regular Graphs

The class of two-spin systems contains several important models, including random independent sets and the Ising model of statistical physics. We show that for both the hard-core (independent set) model and the anti-ferromagnetic Ising model with arbitrary external field, it is NP-hard to approximate the partition function or approximately sample from the model on regular graphs when the model has non-uniqueness on the corresponding regular tree. Together with results of Jerrum -- Sinclair, Weitz, and Sinclair -- Srivastava -- Thurley giving FPRAS's for all other two-spin systems except at the uniqueness threshold, this gives an almost complete classification of the computational complexity of two-spin systems on bounded-degree graphs. Our proof establishes that the normalized log-partition function of any two-spin system on bipartite locally tree-like graphs converges to a limiting ``free energy density'' which coincides with the (non-rigorous) Be the prediction of statistical physics. We use this result to characterize the local structure of two-spin systems on locally tree-like bipartite expander graphs, which then become the basic gadgets in a randomized reduction to approximate MAX-CUT. Our approach is novel in that it makes no use of the second moment method employed in previous works on these questions.
Gravitational collapse of a susy star

Abstract The evidence for a positive vacuum energy in our universe suggests that we might be living in a false vacuum destined to ultimately decay to a true vacuum free of dark energy. At present the simplest example of such a universe is one that is exactly supersymmetric (susy). It is expected that the nucleation rate of critically sized susy bubbles will be enhanced in regions of high density such as in degenerate stars. The consequent release of energy stored in Pauli towers provides a possible model for gamma ray bursts. Whether or not all or any of the currently observed bursts are due to this mechanism, it is important to define the signatures of this susy phase transition. After such a burst, due to the lifting of degeneracy pressure, the star would be expected to collapse into a black hole even though its mass is below the Chandrasekhar limit. Previous studies have treated the star as fully releasing its stored energy before the collapse. In this article we make an initial investigation of the effects of the collapse during the gamma ray emission.
Coarse-grained back reaction in single scalar field driven inflation

We introduce a self-consistent stochastic coarse-graining method, which includes both metric and scalar field fluctuations, to investigate the back reaction of long-wavelength perturbations in single-scalar driven inflation, up to the second (one loop) order. We demonstrate that, although back reaction cannot be significant during the last 70 e-foldings of inflation with a smooth potential, there exist non-smooth inflaton potentials which allow significant back reaction, and are also consistent with cosmological observations. Such non-smooth potentials may lead to the generation of massive primordial black holes, which could be further used to constrain/verify these models.
Iron-catalyzed kinetic resolution of N-sulfonyl oxaziridines

We have developed a highly selective kinetic resolution of N-sulfonyl oxaziridines. This reaction utilizes an inexpensive and easily synthesized iron bis(oxazoline) catalyst to promote the efficient rearrangement of oxaziridines to the corresponding N-sulfonyl imides; no sacrificial reagents are required to effect this resolution. This process is readily translated to gram scale, which provides a practical method for the preparation of structurally diverse, enantiopure N-sulfonyl oxaziridines for use as reagents in organic synthesis.