cssi/SciSciGPT-SciSciNet huggingface dataset:
A tilted-dipole MHD model of the solar corona and solar wind

[1] We simulate the three-dimensional structure of the heliosphere during solar activity minimum by specifying boundary conditions at the coronal base. We compare the output of the model with Ulysses observations obtained during the spacecraft's first fast latitude transition in 1994–1995. The polytropic MHD equations are solved for a steady coronal outflow that includes the addition of Alfven wave momentum and energy in the WKB approximation. A solution for the outflow in a tilted dipole magnetic field in the inner computational region (1–20 R⊙) is combined with a three-dimensional solution in the outer region which extends to 10 AU. The inner region solution is essentially the same as in the work of Usmanov et al. [2000] but has been obtained for slightly different boundary conditions using a different numerical algorithm. The dipole orientation is chosen to match the one inferred from photospheric magnetic field observations at the Wilcox Solar Observatory. The steady solution in the outer region is constructed using a marching-along-radius method and models both solar rotation and interaction regions. The bimodality of solar wind with a rapid change in flow parameters with latitude and the observed extent of the slower wind belt are reproduced well. We compare our simulation also with the results of Bruno et al. [1986] and empirical models of coronal density. We show that the simulation results are in good agreement with the empirical model of Wang and Sheeley [1990].
Off-line and on-line guaranteed start-up delay for Media-on-Demand with stream merging

Abstract We address the problem of designing efficient algorithms for media-on-demand in systems that use stream merging. In the stream merging model the receiving bandwidth of clients is larger than the playback bandwidth, and clients can buffer parts of the transmission to be played back later. Our goal is to minimize the required server bandwidth for a given guaranteed start-up delay and uninterrupted playback. We construct an efficient O ( n ) optimal off-line algorithm for a time horizon that is composed of n time slots, where the length of one slot is the guaranteed start-up delay. Our algorithm works for either clients with receiving bandwidth twice as much as the playback bandwidth or for receiving bandwidth equal to the server bandwidth, independent of the clients buffer size. We describe an on-line delay guaranteed algorithm that operates without knowledge of the time horizon size, and show that it performs asymptotically close to the optimal off-line algorithm. The on-line algorithm is simpler to implement than previously proposed on-line stream merging algorithms, and empirically performs well when the intensity of client arrivals is high.
Matching Methods for Obtaining Survival Functions to Estimate the Effect of a Time-Dependent Treatment

In observational studies of survival time featuring a binary time-dependent treatment, the hazard ratio (an instantaneous measure) is often used to represent the treatment effect. However, investigators are often more interested in the difference in survival functions. We propose semiparametric methods to estimate the causal effect of treatment among the treated with respect to survival probability. The objective is to compare post-treatment survival with the survival function that would have been observed in the absence of treatment. For each patient, we compute a prognostic score (based on the pre-treatment death hazard) and a propensity score (based on the treatment hazard). Each treated patient is then matched with an alive, uncensored and not-yet-treated patient with similar prognostic and/or propensity scores. The experience of each treated and matched patient is weighted using a variant of Inverse Probability of Censoring Weighting to account for the impact of censoring. We propose estimators of the treatment-specific survival functions (and their difference), computed through weighted Nelson-Aalen estimators. Closed-form variance estimators are proposed which take into consideration the potential replication of subjects across matched sets. The proposed methods are evaluated through simulation, then applied to estimate the effect of kidney transplantation on survival among end-stage renal disease patients using data from a national organ failure registry.
Effect of hydrogen on the electronic structure of a grain boundary in iron

Abstract LMTO-ASA calculations were performed on a 26-atom supercell model of a Σ3 (111) grain boundary (GB) in bcc Fe. The supercell emulated two GB's with 11 (111) planes of Fe atoms between the GB planes. One of the GB's was clean, with a structural vacancy at the GB core in the center of a trigonal prism of Fe atoms, while on the other GB this site was occupied by a H atom. The interplanar spacings of the supercell were relaxed using a modified embedded atom method. As in the case of P and S in a similar GB environment in Fe there is only a weak interaction between H and nearest Fe atoms. Almost all the Fe d-states are nonbonding. A very weak covalent bond exists between H and Fe due to s-pd hybridization, the hybrid bonding band located far below the Fermi energy. This bond is mostly of α-type, connecting H with Fe atoms in the GB plane; the δ- component of this bond across the GB is weaker. Contrary to a general belief, H on the GB does not contribute any significant electron charge to Fe valence d-bands. A weak electrostatic interaction attracts Fe-atoms across the clean GB, but results in repulsion if a H atom is present. The magnetic contribution to intergranular cohesion is decreased when H is present due to the suppression of the magnetic moments of the nearest Fe atoms both in the GB plane and directly across the GB.
Joint modeling of recurrent event processes and intermittently observed time-varying binary covariate processes

When conducting recurrent event data analysis, it is common to assume that the covariate processes are observed throughout the follow-up period. In most applications, however, the values of time-varying covariates are only observed periodically rather than continuously. A popular ad-hoc approach is to carry forward the last observed covariate value until it is measured again. This simple approach, however, usually leads to biased estimation. To tackle this problem, we propose to model the covariate effect on the risk of the recurrent events through jointly modeling the recurrent event process and the longitudinal measures. Despite its popularity, estimation of the joint model with binary longitudinal measurements remains a challenge, because the standard linear mixed effects model approach is not appropriate for binary measures. In this paper, we postulate a Markov model for the binary covariate process and a random-effect proportional intensity model for the recurrent event process. We use a Markov chain Monte Carlo algorithm to estimate all the unknown parameters. The performance of the proposed estimator is evaluated via simulations. The methodology is applied to an observational study designed to evaluate the effect of Group A streptococcus on pharyngitis among school children in India.
Generation and intramolecular cyclization of (2-ethenylphenyl)bisketenes. Synthesis of benzofuranones

Abstract Several new differentially substituted cyclobutenediones 4a-e have been prepared. Their thermal rearrangement to substituted naphthofuranones 5a-d is reported. This rearrangement involves an unprecedented intramolecular cyclization of a reactive bisketene 6, and forms the naphthofuranone system in good yield.
Collider and dark matter searches in models with mixed modulus-anomaly mediated SUSY breaking

We investigate the phenomenology of supersymmetric models where moduli fields and the Weyl anomaly make comparable contributions to SUSY breaking effects in the observable sector of fields. This mixed modulus-anomaly mediated supersymmetry breaking (MM-AMSB) scenario is inspired by models of string compactification with fluxes, which have been shown to yield a de Sitter vacuum (as in the recent construction by Kachru et al). The phenomenology depends on the so-called modular weights which, in turn, depend on the location of various fields in the extra dimensions. We find that the model with zero modular weights gives mass spectra characterized by very light top squarks and/or tau sleptons, or where M1 ~ ?M2 so that the bino and wino are approximately degenerate. The top squark mass can be in the range required by successful electroweak baryogenesis. The measured relic density of cold dark matter can be obtained via top squark co-annihilation at low tan ?, tau slepton co-annihilation at large tan ? or via bino-wino coannihilation. Then, we typically find low rates for direct and indirect detection of neutralino dark matter. However, essentially all the WMAP-allowed parameter space can be probed by experiments at the CERN LHC, while significant portions may also be explored at an e+e? collider with s1/2 = 0.5?1 TeV. We also investigate a case with non-zero modular weights. In this case, co-annihilation, A-funnel annihilation and bulk annihilation of neutralinos are all allowed. Results for future colliders are qualitatively similar, but prospects for indirect dark matter searches via gamma rays and anti-particles are somewhat better.
Enantioselective Construction of All-Carbon Quaternary Centers by Branch-Selective Pd-Catalyzed Allyl–Allyl Cross-Coupling

The Pd-catalyzed cross-coupling of racemic tertiary allylic carbonates and allylboronates is described. This reaction generates all-carbon quaternary centers in a highly regioselective and enantioselective fashion. The outcome of these reactions is consistent with a process that proceeds by way of 3,3′-reductive elimination of bis(η1-allyl)palladium intermediates. Strategies for distinguishing the product alkenes and application to the synthesis of (+)-α-cuparenone are also described.
TWO-DIMENSIONAL METAL-AMMONIA-SOLUTIONS IN GRAPHITE

The preparation structural properties and electrical properties of metal-ammonia-solutions intercalated into graphite are briefly reviewed. It will be shown that the metal-ammonia-solutions in graphite are both the two-dimensional structural and electrical analogues of the more familiar bulk three-dimensional metal-ammonia solutions. These conclusions are supported by the results and interpretations of a number of physical measurements including elastic X-ray and neutron scattering, anisotropic transport studies and optical reflectivity studies.
Addition of alkynes to aldehydes and activated ketones catalyzed by rhodium-phosphine complexes.

A mixture of 2-(di-tert-butylphosphino)biphenyl and dicarbonylacetonato rhodium(I) provides an effective catalyst system for the addition of alkynes to aldehydes and activated ketones. In contrast to the more common zinc-catalyzed processes, enolizable 1,2-dicarbonyls are excellent substrates for these rhodium-catalyzed additions. This reaction allows for the formation of propargylic alcohols under mild conditions, tolerating many functional groups (such as carboxylic acids) that are incompatible with other methods. Little selectivity was observed in cases of unsymmetrical 1,2-diketones. Addition of alkynes to aldehydes with an adjacent chirality center usually provides the Felkin addition product with excellent selectivity in some cases. Studies on the catalyst structure show that both the β-diketonate and a carbon monoxide ligand appear to be bound to the active catalyst. The use of chiral phosphines to induce asymmetry in the propargyl alcohol products provided low enantioselectivity, which may be due ...
Chemistry and biochemistry of 13C hyperpolarized magnetic resonance using dynamic nuclear polarization.

The study of transient chemical phenomena by conventional NMR has proved elusive, particularly for non-1H nuclei. For 13C, hyperpolarization using the dynamic nuclear polarization (DNP) technique has emerged as a powerful means to improve SNR. The recent development of rapid dissolution DNP methods has facilitated previously impossible in vitro and in vivo study of small molecules. This review presents the basics of the DNP technique, identification of appropriate DNP substrates, and approaches to increase hyperpolarized signal lifetimes. Also addressed are the biochemical events to which DNP-NMR has been applied, with descriptions of several probes that have met with in vivo success.
Mechanical relaxation of localized residual stresses associated with foreign object damage

Abstract Foreign-object damage associated with the ingestion of debris into aircraft turbine engines can lead to a marked degradation in the high-cycle fatigue (HCF) life of turbine components. This degradation is generally considered to be associated with the premature initiation of fatigue cracks at or near the damage sites; this is suspected to be due to, at least in part, the impact-induced residual stress state, which can be strongly tensile in these locations. However, recent experimental studies have shown the unexpected propensity for impact-induced fatigue crack formation at locations of compressive residual stress in the vicinity of the impact site. To address this issue, in situ and ex situ spatially-resolved X-ray diffraction and numerical modeling are utilized to show that the initial residual stress state can be strongly relaxed during the fatigue loading process. The magnitude and rate of relaxation is strongly dependent on the applied loads. For a Ti–6Al–4V turbine blade alloy, little relaxation was observed for an applied maximum stress of 325 MPa (0.35 σ y , where σ y is the yield stress), and cracks tended to form in subsurface zones of tensile residual stress away from the damage sites. In contrast, at an applied maximum stress of 500 MPa (0.54 σ y ), equal to the smooth-bar 10 7 -cycle endurance strength, cracks tended to form at the damage sites in zones of high stress concentration that had initially been in strong compression, but had relaxed during the fatigue loading.
An Essay on Stellar Oscillations and Evolution

It is cautioned that solar models adjusted in such a way as to achieve a match between theoretical solar oscillation characteristics and observed ones may produce neutrino fluxes inconsistent with the observations and that this is likely to be explicable as a deficiency in modeling that portion of the envelope which is most strongly affected by uncertainties in the treatment of convection. Then follows a summary of how the results of pulsation theory and of stellar evolution theory have been used together to learn about the structure and evolution of RR Lyrae stars, classical Cepheids, and high luminosity AGB stars.
A logic for reasoning about ambiguity

Standard models of multi-agent modal logic do not capture the fact that information is often ambiguous, and may be interpreted in different ways by different agents. We propose a framework that can model this, and consider different semantics that capture different assumptions about the agents' beliefs regarding whether or not there is ambiguity. We examine the expressive power of logics of ambiguity compared to logics that cannot model ambiguity, with respect to the different semantics that we propose.
Reply to Comments of Steuernagel on the Afshar’s Experiment

We respond to criticism of our paper “Paradox in Wave-Particle Duality for Non-Perturbative Measurements”. We disagree with Steuernagel’s derivation of the visibility of the Afshar experiment. To calculate the fringe visibility, Steuernagel utilizes two different experimental situations, i.e. the wire grid in the pattern minima and in the pattern maxima. In our assessment, this procedure cannot lead to the correct result for the complementarity properties of a wave-particle in one particular experimental set-up.
Bounding Betti numbers of bipartite graph ideals

Abstract We prove a conjectured lower bound of Nagel and Reiner on Betti numbers of edge ideals of bipartite graphs.
Study of Ball Bearing Torque Under Elastohydrodynamic Lubrication

Spinning and rolling torques were measured in an angular-contact ball bearing with and without a cage under several lubrication regimes in a modified NASA spinning torque apparatus. Two lubricants were used—a di-2 ethylhexyl sebacate and a synthetic paraffinic oil, at shaft speeds of 1000, 2000, and 3000 rpm and bearing loads from 45 newtons (10 lb) to 403 newtons (90 lb). An analytical model was developed from previous spinning friction models to include rolling with spinning under lubrication regimes from thin film to flooded conditions. The bearing torque values have a wide variation, under any condition of speed and load, depending on the amount of lubricant present in the bearing. The analytical model compared favorably with experimental results under several lubrication regimes.
Solar Energy Microclimate As Determined From Satellite Observations

A method is presented for determining solar insolation at the earth's surface using satellite broadband visible radiance and cloud imagery data, along with conventional in situ measurements. Conventional measurements are used to both tune satellite measurements and to develop empirical relationships between satellite observations and surface solar insolation. Cloudiness is the primary modulator of sunshine. The satellite measurements as applied in this method consider cloudiness both explicitly and implicitly in determining surface solar insolation at space scales smaller than the conventional pyranometer network.
Crystal engineering supported by the [Re6(μ3-Se)8]2+ core-containing clusters

Transition metal clusters are a unique class of chemical substances. Their well-defined molecular structures and interesting materials properties (e.g. optical, magnetic, and catalytic) make them unique building blocks in supramolecular construction. In this highlight, our efforts in utilizing site-differentiated cluster complexes of the [Re6(μ3-Se)8]2+ core as stereospecific building units for a great variety of crystal-engineered multicluster arrays are summarized. The findings from this research not only establish the superior utility of these novel building blocks for the creation of structurally sophisticated architectures and possibly functional materials, they also and probably more importantly, indicate what promises to be an exciting new direction in cluster chemistry.
A counterexample to the Alon-Saks-Seymour conjecture and related problems

Consider a graph obtained by taking an edge disjoint union of k complete bipartite graphs. Alon, Saks, and Seymour conjectured that such graphs have chromatic number at most k+1. This well known conjecture remained open for almost twenty years. In this paper, we construct a counterexample to this conjecture and discuss several related problems in combinatorial geometry and communication complexity.
Integrable structures in supersymmetric gauge and string theory

Abstract The effective action of N = 2 Yang-Mills theory with adjoint matter is shown to be governed by an integrable spin model with spectral parameter on an elliptic curve. We sketch a route to deriving this effective dynamics from the underlying Yang-Mills theory. Natural generalizations of this structure to all N = 2 models, and to string theory, are suggested.
Variations in the Photo-Electric Sensitivity of Platinum.

The photo-electric properties of a platinum surface which has undergone an extended process of outgassing by heat treatment have been studied by many recent observers and conflicting results have been reported.
Confirming the Detection of an Intergalactic X-Ray Absorber toward PKS 2155–304

We present new observations of PKS 2155-304 with the Chandra Low Energy Transmission Grating (LETG), using the Advanced CCD Imaging Spectrometer (ACIS). We confirm the detection of an absorption line plausibly identified as O VIII Ly? from a warm-hot intergalactic medium associated with a small group of galaxies along the line of sight, as originally reported by Fang and coworkers. Combining the previous observations by Fang and coworkers with five new long observations on the same target, we increase the total exposure time by a factor of 3 and the total counts per resolution element by a factor of 5. The measured line equivalent width is smaller than that observed by Fang and coworkers, but still consistent at 90% confidence. We also analyze the XMM-Newton observations on the same target, as well as observations using the combination of the Chandra LETG and the High Resolution Camera (HRC). These observations have been used to challenge our reported detection. While no line is seen in either the XMM-Newton or the Chandra LETG+HRC data, we find that our result is consistent with the upper limits from both data sets. We attribute the nondetection to (1) the higher quality of the Chandra LETG+ACIS spectrum and (2) the rather extended wings of the line-spread functions of both the XMM-Newton Reflection Grating Spectrometer (RGS) and the Chandra LETG+HRC. We discuss the implication of our observation on the temperature and density of the absorber. We also confirm the detection of z ~ 0 O VII absorption, and, comparing with previous Chandra analysis, we obtain much tighter constraints on the line properties.
Holography with Ramond-Ramond fluxes

Starting from the non-linear sigma model of the IIB string in the light-cone gauge, we analyze the role of RR fluxes in Holography. We find that the worldsheet theory of states with only left or right moving modes does not see the presence of RR fields threading a geometry. We use this significant simplification to compute part of the strong coupling spectrum of the two dimensional NCOS theory. We also reproduce the action of a closed string in a PP-wave background using this general formalism; and we argue for various strategies to find new systems where the closed string theory may be exactly solvable.
Quantile-Regression Estimates of Cigarette Demand Elasticities for the United States

Using a simple model and state-level cross-section U.S. data from 1993 to 1999, quantile-regression estimates of price elasticity and income elasticity for cigarette demand are obtained. It is noted that price elasticity shows a sizable variation across the high and low quantity-quartiles. There is a similar variability in the income elasticity, but most of these estimates lack statistical significance. Besides providing an indication of the variation in the price (and income) elasticity for different consumption levels, the exercise suggests some interpretative caution in regard to estimates from constant-elasticity models.
On Adding a Mean Structure to a Covariance Structure Model

The vast majority of structural equation models contains no mean structure, that is, the population means are estimated at the sample means and then eliminated from modeling consideration. Generalized least squares methods are proposed to estimate potential mean structure parameters and to evaluate whether the given model can be successfully augmented with a mean structure. A simulation evaluates the performance of some alternative tests. A method that takes variability due to the estimation of covariance structure parameters into account in the mean structure estimator, as well as in the weight matrix of the generalized least squares function, performs best. In small samples, the F test and Yuan-Bentler adjusted chi-square test perform best. For example, if there is interest in modeling whether arithmetic skills or vocabulary levels are increasing across time, as one would expect in school, an analysis of means is an essential modeling component.
Adaptive aspirations and contributions to a public good: Generic advertising as a response to decline☆

Abstract Generic advertising, the promotion of an entire product or service category, is a common form of inter-firm cooperation. Voluntary participation in such a campaign represents contribution to a public good. Based on the pattern of recent campaigns, we argue that this cooperation is dependent on adaptive aspirations and an increased willingness to consider alternative courses of action in light of declining sales within an industry. Three experiments are reported that tested these ideas. In each study, subjects assigned to four person groups chose how many resources to contribute to a generic advertising campaign the effectiveness of which depended on total funding levels. Each group member represented a different “store” in the same mall. The instructions framed the problem by presenting varying sales trends for the stores—Positive, Negative, or Neutral. The first two experiments were one-shot games with a dominant strategy of non-contribution and free riding. The results showed that subjects confronting the declining trend contributed significantly more than those in either of the other two conditions. A declining sales trend also positively influenced their expectations that others would contribute as well. The third experiment demonstrated that a decline-induced equilibrium persisted over trials of a finitely repeated game with a known stopping point. Contributions remained high even in the final round. Surprisingly, the specific identification of a competitor mall as the cause of the decline in sales actually resulted in lower levels of contribution. The implications for research and practice are discussed.
Dynamic Models of the Term Structure

In the past 25 years, tremendous progress has been made in modeling the dynamics of the term structure of interest rates, which play an instrumental role in determining prices and hedging portfolios of fixed-income derivative securities. This article reviews the theoretical development of the dynamic models of the default-free term structure and their applications in pricing interest rate options. Classic models, sometimes termed equilibrium models, and their multifactor extensions are outlined. These models provide clear economic intuitions connecting the term structure with economic fundamentals. They also lay a foundation for the framework of the arbitrage models that price interest rate derivatives on the basis of the market prices of bonds. This framework has been expanded and enriched by recent advances in directly modeling observable market rates through the market models and in incorporating an internally consistent correlation structure through the “infinite-dimensional” models.
Research in Agricultural Economics 1919–1990: Seventy-Two Years of Change

This paper examines historical trends in the evolution of research using econometrics, simulation, and operations research within agricultural economics. An examination of articles in the American Journal of Agricultural Economics and the Journal of Farm Economics was conducted. Articles were classified according to the type of quantitative technique employed. Trends were identified and analyzed to reveal changes in quantitative techniques favored by agricultural economics researchers.
Late neoplastic changes following medical irradiation

New additions since 1968 to the literature on radiation carcinogenesis in man support the earlier conclusion of an approximately linear increase in cancer incidence in a broad intermediate dose range for most sites of cancer. Questions are raised regarding the nature of the dose-response relation at very low and at very high dose exposures. Analyses of some data on exposure to radiation from internal deposits of radioactive material suggest that the dose- response curve at low and intermediate ranges is concave up, implying a smaller effect per unit exposure at very low doses than at intermediate ranges. Data on exposure to the very high but anatomically limited doses of radiation used in cancer therapy give conflicting results, suggesting in one report a continuation of the linear relation into the high-dose range. Other reports suggest a lesser effect per unit dose at high doses than at intermediate doses. Extensive laboratory studies of exposure of experimental animals indicate that over broad dose ranges, exceptions to simple linear relations are the rule, and that factors of dose rate and fractionation also affect the dose-response relation. (auth)
Red mergers and the assembly of massive elliptical galaxies: the fundamental plane and its projections

Several recent observations suggest that gas-poor (dissipationless) mergers of elliptical galaxies contribute significantly to the build-up of the massive end of the red sequence at z? 1. We perform a series of major merger simulations to investigate the spatial and velocity structure of the remnants of such mergers. Regardless of orbital energy or angular momentum, we find that the stellar remnants lie on the fundamental plane defined by their progenitors, a result of virial equilibrium with a small tilt due to an increasing central dark matter fraction. However, the locations of merger remnants in the projections of the fundamental plane - the Faber-Jackson and R e -M * relations - depend strongly on the merger orbit, and the relations steepen significantly from the canonical scalings (L ∝ σ 4 e and R e ∝ M 0.6 * ) for mergers on radial orbits. This steepening arises because stellar bulges on orbits with lower angular momentum lose less energy via dynamical friction on the dark matter haloes than do bulges on orbits with substantial angular momentum. This results in a less tightly bound remnant bulge with a smaller velocity dispersion and a larger effective radius. Our results imply that the projections of the fundamental plane - but not necessarily the plane itself - provide a powerful way of investigating the assembly history of massive elliptical galaxies, including the brightest cluster galaxies at or near the centres of galaxy clusters. We argue that most massive ellipticals are formed by anisotropic merging and that their fundamental plane projections should thus differ noticeably from those of lower mass ellipticals even though they should lie on the same fundamental plane. Current observations are consistent with this conclusion. The steepening in the L-σ e relation for luminous ellipticals may also be reflected in a corresponding steepening in the M BH-σe relation for massive black holes.
Short-distance correlation properties of the Lieb-Liniger system and momentum distributions of trapped one-dimensional atomic gases.

We derive exact closed-form expressions for the first few terms of the short-distance Taylor expansion of the one-body correlation function of the Lieb-Liniger gas. As an intermediate result, we obtain the high-$p$ asymptotics of the momentum distribution of both free and harmonically trapped atoms and show that it obeys a universal $1/{p}^{4}$ law for all values of the interaction strength. We discuss the ways to observe the predicted momentum distributions experimentally, regarding them as a sensitive identifier for the Tonks-Girardeau regime of strong correlations.
Aeroelastic flutter and divergence of stiffness coupled, graphite/epoxy cantilevered plates

An analytical and experimental investigation was conducted to determine the aeroelastic flutter and divergence behavior of unswept, rectangular wings simulated by graphite/epox y, cantilevered plates with various amounts of bending-torsi on stiffness coupling. The analytical approach incorporated a Rayleigh-Ritz energy formulation and unsteady, incompressible two-dimensional aerodynamic theory. Flutter and divergence velocities were obtained using the \ -g method and compared to results of low-speed wind tunnel tests. Stall flutter behavior was also examined experimentally. There was good agreement between analytical and experimental results. Wings with negative stiffness coupling exhibited divergence, while positive coupling delayed the onset of stall flutter.
Flutter and Buckling of General Laminated Plates

An anisotropic buckling and flutter analysis is developed with allowance for both bending-extensional coupling and bending-twisting coupling within the framework of linear small deflection theory for simply supported general laminated plates. The extended Galerkin method is used to obtain approximate solutions to the coupled governing equations. The effects of various anisotropic stiffness parameters on the static and dynamic stability of laminated plates are evaluated, with particular emphasis on assessing the range of applicability of classical orthotropic plate theory. It is shown that bending-extensional coupling and bending-twisting stiffness terms have a destabilizing effect on buckling and flutter, the effect being more pronounced for a small number of layers. For symmetric plates, the number of layers required for orthotropic plate theory to be applicable is generally less for the buckling problem than for flutter. For square plates, aligning the fibers with the direction of airflow over the plate surface results in the highest flutter dynamic pressure.
Modelling, simulation and control in a data-rich environment

This paper describes the use and potential use of mathematical modelling, computer simulation, real-time parameter identification and adaptive feedback control techniques in data-rich clinical environments. We consider a system to be operating in a data-rich environment when measurements of system inputs and outputs are frequently available. Two particular application examples which illustrate the power of these techniques will be examined. The first example that will be described involves the development and testing of a real-time adaptive controller for simultaneous regulation of mean arterial pressure and cardiac output using two drugs. The second application of these techniques involves the real-time control of electrical stimulation for the functional use of paralyzed muscles in neuroprosthetic devices.
Laser-based dynamic evaporation and surface shaping of fused silica with assist gases: a path to rimless laser machining

Evaporation and ablation are fundamental processes which drive laser-material processing performance. In applications where surface shape is important, control of the temperature field and the resulting spatially varying material response must be considered. For that purpose, assist gases are useful in, first, lowering treatment temperatures and, second, in changing interfacial and bulk chemistry to limit capillary-driven flow. Additionally, laser-matter coupling is influenced by pulse length as it determines the heat affected zone. Using infrared imaging of CO2 laser-heated fused silica and surface profile measurements, we derive temperature and time dependent pitting rates along with shapes for a range of gases that include hydrogen, nitrogen, air, and helium. In the range of 1,500–4,500 K, evaporation, flow, and densification are shown to contribute to the pit shape. Analysis reveals a strong and complex dependence of rim formation on heating time and gas chemistry, mostly by lowering treatment temperature. Under dynamic heating, chemicapillarity appears to help in lowering rim height, in spite of the reactants mass transport limitations. Results on this gas-assisted approach suggest the possibility for sub-nanometer “rimless” laser-based machining.
The reliability horizon for semi-classical quantum gravity: metric fluctuations are often more important than back-reaction

Abstract In this note I introduce the notion of the “ reliability horizon ” for semi-classical quantum gravity. This reliability horizon is an attempt to quantify the extent to which we should trust semi-classical quantum gravity, and to get a better handle on just where the “ Plack regime ” resides. I point out that the key obstruction to pushing semi-classical quantum gravity into the Planck regime is often the existence of large metric fluctuations, rather than a large back-reaction. There are many situations where the metric fluctuations become large long before the back-reaction is significant. Issues of this type are fundamental to any attempt at proving Hawking's chronology protection conjecture from first principles, since I shall prove that the onset of chronology violation is always hidden behind the reliability horizon.
Wong-Zakai type convergence in infinite dimensions

The paper deals with convergence of solutions of a class of stochastic differential equations driven by infinite-dimensional semimartingales. The infinite dimensional semimartingales considered in the paper are Hilbert-space valued. The theorems presented generalize the convergence result obtained by Wong and Zakai for stochastic differential equations driven by linear interpolations of a finite-dimensional Brownian motion. In particular, a general form of the correction factor is derived. Examples are given illustrating the use of the theorems to obtain other kinds of approximation results.
Nuclear pairing and Coriolis effects in proton emitters

We introduce a Hartree-Fock-Bogoliubov mean-field approach to treat the problem of proton emission from a deformed nucleus. By substituting a rigid rotor in a particle-rotor model with a mean field, we obtain a better description of experimental data in 141Ho. The approach also elucidates the softening of kinematic coupling between particle and collective rotation, the Coriolis attenuation problem.
Cosmological Constraints from Compact Radio Source Angular Size versus Redshift Data

We use the Gurvits, Kellermann, & Frey compact radio source angular size versus redshift data to place constraints on cosmological model parameters in models with and without a constant or time-variable cosmological constant. The resulting constraints are consistent with but weaker than those determined using current supernova apparent magnitude versus redshift data.
Identification of Economies of Scope in a Stochastic Production Environment

This paper extends the definition of economies of scope to multioutput firms that face an uncertain production environment. Identification of economies of scope in this environment, however, requires separability assumptions on the technology. These identification restrictions are demonstrated in the paper. For each identification restriction, the definition of economies of scope is generalized to the case of uncertain production and risk aversion. L'article que voici elargit la definition des economies de gamme aux entreprises a produits multiples aux prises avec une situation incertaine au niveau de la production. Pour cerner les economies de gamme dans une telle situation, il faut poser l'hypothese de la separation des technologies. Les auteurs illustrent ces restrictions et generalisent la definition des economies de diversification pour chacune d'elles dans le cas d'une production incertaine et de l'aversion du risque.
Detection of combined occurrences

In this paper it is supposed that the variables x1, … , xn each have finite range with the variable xi taking on pi possible values and that the values of the variables are changing with time. It is supposed further that it is desired to detect occurrences in which some subset of the variables achieve particular values. Finally, it is supposed that the problem involves the detection of a large number of combined occurrences for a large number of changes of values of variables. Two efficient solutions for this problem are described. Both methods have the unusual property of being faster for systems where the sum p1 + … + pn is larger. The first solution is error-free and suitable for most cases. The second solution is slightly more elegant and allows negation as well as conjunction, but is subject to the possibility of errors. An error analysis is given for the second method and an empirical study is reported.
Invariant bilinear forms on a vertex algebra

Abstract In this paper we construct a linear space that parameterizes all invariant bilinear forms on a given vertex algebra with values in a arbitrary vector space. Also we prove that every invariant bilinear form on a vertex algebra is symmetric. This is a generalization of the result of Li (J. Pure Appl. Algebra 96(3) (1994) 279), who proved this for the case when the vertex algebra is non-negatively graded and has finite dimensional homogeneous components. As an application, we introduce a notion of a radical of a vertex algebra. We prove that a radical-free vertex algebra A is non-negatively graded, and its component A0 of degree 0 is a commutative associative algebra, so that all structural maps and operations on A are A0-linear. We also show that in this case A is simple if and only if A0 is a field.
An Integrated Model of Debt Issuance, Refunding, and Maturity

We integrate previous work in this area and develop a multiperiod model that simultaneously determines bond refunding, bond issuance, maturity structure, cash holdings, and bank borrowing policies. The focus here is on providing the required debt funds in the most cost efficient fashion. A strength of the model is that it allows for time varying interest costs, transaction costs, issuance costs, and refunding costs to be firm specific. The output of the model lays out the optimal financing decisions for each time interval that minimize the total discounted cost of providing the funds that match the requisite funds. By limiting the surplus funds available, the model minimizes the management incentive to over invest and thereby reduces the agency costs. The model has economic implications for the financing decisions and the firm's default risk, growth opportunities, riskiness of cash flows, and firm size.
The Clustering of Massive Halos

The clustering properties of dark matter halos are a firm prediction of modern theories of structure formation. We use two large-volume, high-resolution N-body simulations to study how the correlation function of massive dark matter halos depends on their mass, assembly history, and recent merger activity. We find that halos with the lowest concentrations are currently more clustered than those of higher concentration, the size of the effect increasing with halo mass; this agrees with trends found in studies of lower mass halos. The clustering dependence on other characterizations of the full mass accretion history appears weaker than the effect with concentration. Using the integrated correlation function, marked correlation functions, and a power-law fit to the correlation function, we find evidence that halos that have recently undergone a major merger or a large mass gain have slightly enhanced clustering relative to a randomly chosen population with the same mass distribution.
Realization of the exactly solvable Kitaev honeycomb lattice model in a spin-rotation-invariant system

The exactly solvable Kitaev honeycomb lattice model is realized as the low-energy effect Hamiltonian of a spin-1/2 model with spin rotation and time-reversal symmetry. The mapping to low-energy effective Hamiltonian is exact without truncation errors in traditional perturbation series expansions. This model consists of a honeycomb lattice of clusters of four spin-1/2 moments and contains short-range interactions up to six-spin (or eight-spin) terms. The spin in the Kitaev model is represented not as these spin-1/2 moments but as pseudospin of the two-dimensional spin-singlet sector of the four antiferromagnetically coupled spin-1/2 moments within each cluster. Spin correlations in the Kitaev model are mapped to dimer correlations or spin-chirality correlations in this model. This exact construction is quite general and can be used to make other interesting spin-1/2 models from spin-rotation invariant Hamiltonians. We discuss two possible routes to generate the high-order spin interactions from more natural couplings, which involves perturbative expansions thus breaks the exact mapping, although in a controlled manner.
A manufacturing hand

Abstract In unmanned Flexible Manufacturing Cells, robots can be used for loading machines, inspection activities, and assembly operations. What kind of robotic end-effector should be built for such tasks? The human hand has evolved to be a general purpose manipulator that adapts to the richness of our daily lives but, in doing so, it is not particularly suited to manufacturing operations. Here, we rely heavily on special tools, fixtures, and protective layers. This paper describes the initial development of a hand specifically for manufacturing work. This has involved the manufacture of an instrumented wrist with an adjustable remote center of compliance, and the design of fingers for gripping. Object shapes have also been analysed in order to provide for a stable static grip. Importantly, these studies of the physical aspects of prehension have been matched to tasks. The research has considered a range of industrial operations and specified the level of end-effector control needed. This work is leading to some design guides for robotic end-effectors which, it is hoped, will be of use to industrial designers.
Rhodium(III)-Catalyzed Arylation of Boc-Imines via C−H Bond Functionalization

The first rhodium-catalyzed arylation of imines proceeding via C−H bond functionalization is reported. Use of a non-coordinating halide abstractor is important to obtain reactivity. Aryl-branched N-Boc-amines are formed, and a wide range of functionality is compatible with the reaction.
Reputation and performance fee effects on portfolio choice by investment advisers

Abstract This paper examines a two-period model of investment management. Investors reallocate their wealth between two mutual funds managed by different investment advisers after observing the performance of each adviser in the first period. A reputation effect causes one adviser to choose a portfolio in the first period that is extreme given his private information about asset returns. Extreme portfolios are costly for risk-averse advisers and investors because mutual funds are riskier than in one-period or single-adviser settings. Adoption of a performance fee mitigates undesirable reputation effects and results in superior ex ante payoffs to investors.
Equilibrium Star Cluster Formation

We argue that rich star clusters take at least several local dynamical times to form and so are quasi-equilibrium structures during their assembly. Observations supporting this conclusion include morphologies of star-forming clumps, momentum flux of protostellar outflows from forming clusters, age spreads of stars in the Orion Nebula cluster (ONC) and other clusters, and the age of a dynamical ejection event from the ONC. We show that these long formation timescales are consistent with the expected star formation rate in turbulent gas, as recently evaluated by Krumholz & McKee. Finally, we discuss the implications of these timescales for star formation efficiencies, the disruption of gas by stellar feedback, mass segregation of stars, and the longevity of turbulence in molecular clumps.