cssi/SciSciGPT-SciSciNet huggingface dataset:
Design and development considerations for biologically inspired flapping-wing micro air vehicles

In this paper, the decade of numerical and experimental investigations leading to the development of the authors’ unique flapping-wing micro air vehicle is summarized. Early investigations included the study of boundary layer energization by means of a small flapping foil embedded in a flat-plate boundary layer, the reduction of the recirculatory flow region behind a backward-facing step by means of a small flapping foil, and the reduction or suppression of flow separation behind blunt or cusped airfoil trailing edges by flapping a small foil located in the wake flow region. These studies were followed by systematic investigations of the aerodynamic characteristics of single flapping airfoils and airfoil combinations. These unsteady flows were described using flow visualization, laser-Doppler velocimetry in addition to panel and Navier-Stokes computations. It is then shown how this flapping-wing database was used to conceive, design and develop a micro air vehicle which has a fixed wing for lift and two flapping wings for thrust generation. While animal flight is characterized by a coupled force generation, the present design appears to separate lift and thrust. However, in fact, the performance of one surface is closely coupled to the other surfaces.
Exploring the outer limits of numerical relativity

We perform several black-hole binary evolutions using fully nonlinear numerical relativity techniques at separations large enough that low-order post-Newtonian expansions are expected to be accurate. As a case study, we evolve an equal-mass nonspinning black-hole binary from a quasicircular orbit at an initial coordinate separation of $D=100M$ for three different resolutions. We find that the orbital period of this binary (in the numerical coordinates) is $T=6422M$. The orbital motion agrees with post-Newtonian predictions to within 1%. However, we find that the time derivative of the coordinate separation is dominated by a purely gauge effect leading to an apparent contraction and expansion of the orbit at twice the orbital frequency. Based on these results, we improved our evolution techniques and studied a set of black hole binaries in quasicircular orbits starting at $D=20M$, $D=50M$, and $D=100M$ for $\ensuremath{\sim}5$, 3, and 2 orbits, respectively. We then find good agreement between the numerical results and post-Newtonian predictions for the orbital frequency and radial decay rate, radiated energy and angular momentum, and waveform amplitude and phases. The results are relevant for the future computation of long-term waveforms to assist in the detection and analysis of gravitational waves by the next generation of detectors as well as the long-term simulations of black-hole binaries required to accurately model astrophysically realistic circumbinary accretion disks.
Modeling of an Ionic Liquid Electrospray using a Molecular Dynamics Model

Molecular dynamics simulations have been performed to investigate the behavior of the EMIM-BF4 ionic liquid for conditions similar to those of electrospray thrusters. To study the physics of ion extrusion a large system composed of approximately 2,160 ion pairs was placed inside a platinum capillary and equilibrated. An electric field was applied to the system in the longitudinal direction and the fraction of solvated and non-solvated emitted ions, as well as the internal configuration of those clusters, were analyzed. A moving potential wall model was used to generate a mass flow inside the capillary and a Taylor cone was observed in the case of an extrusion event with ionic liquid mass flow.
Global synchronization of pulse-coupled oscillators interacting on cycle graphs

The importance of pulse-coupled oscillators (PCOs) in biology and engineering has motivated research to understand basic properties of PCO networks. Despite the large body of work addressing PCOs, a global synchronization result for networks that are more general than all-to-all connected is still unavailable. In this paper we address global synchronization of PCO networks described by cycle graphs. It is shown for the bidirectional cycle case that as the number of oscillators in the cycle grows, the coupling strength must be increased in order to guarantee synchronization for arbitrary initial conditions. For the unidirectional cycle case, the strongest coupling cannot ensure global synchronization yet a refractory period in the phase response curve is sufficient to enable global synchronization. Analytical findings are confirmed by numerical simulations.
Rational Cooperation in the Finitely Repeated Prisoner's Dilemma: Experimental Evidence

This paper presents experiments designed to examine the sequential equilibrium reputation hypothesis in the finitely repeated prisoner's dilemma. The authors test the hypothesis by controlling the subjects' ability to build reputations and by manipulating their beliefs that their opponent is irrational or altruistic. The responses of subjects strongly support the sequential equilibrium prediction. The results also suggest an important role for 'homemade altruism,' that is, a natural tendency to cooperate that subjects bring to the experiment from the outside. The authors find that there may be no difference between the beliefs that an opponent is altruistic and the actual chance it is so. Copyright 1993 by Royal Economic Society.
Heterogeneous Nucleation With Artificial Cavities

Bubble incipience in artificial cavities manufactured from silicon has been studied using gas nucleation and pool boiling. Moderately wetting water and highly wetting ethanol have both been used as the bulk fluid with cylindrical cavities, as well as those with a triangle, square, and rectangle shape cross section. Nominal cavity sizes range from 8 to 60 μm. The incipience conditions observed for water using both gas nucleation and pool boiling suggest that bubble initiation originates from a concave meniscus. Corn-well's contact angle hysteresis theory for vapor-trapping cavities is used to explain the gas nucleation results. The pool boiling results are more difficult to explain. Using ethanol, cavities appeared to be completely flooded and were not activated using either gas nucleation or pool boiling. Using water and gas nucleation, cavities were almost always activated, provided the incipience criterion was satisfied; in contrast cavities in pool boiling with water activated with different superheats during different experiments. The difference in incipience behavior between gas nucleation and pool boiling with water is explained based on vapor-trapping and thermal suppression considerations. Based on limited experimental results, it appears that the backpressure does not influence gas bubble incipience, provided the pressure difference is the same. The experimental results presented affirm the theory of heterogeneous nucleation from vapor-trapping cavities provided contact angle hysteresis and vapor trapping are fully accounted for. However, the results also suggest that the theoretical considerations required for a deterministic model for incipience from vapor-trapping cavities during boiling is more complex than previously hypothesized.
Case history of drillstem failures offshore West Africa

This paper reports that a high incidence of drillstem (or drillstring) failures was experienced by Conoco Inc. during drilling of exploration wells offshore West Africa. A data base of failure information was used to identify quickly where the majority of the problems occurred. Almost all failures were related to fatigue and corrosion. A study resulted in several recommendations that included improved practices in drill stem selection, quality assurance, and corrosion control. After the recommendations were implemented, a significant reduction in failures was recorded. This increased operating efficiency, reduced drilling costs, and improved safety.
Electrically tunable quantum spin Hall state in topological crystalline insulator thin films

Based on electronic structure calculations and theoretical analysis, we predict the (111) thin films of the SnTe class of three-dimensional (3D) topological crystalline insulators (TCIs) realize the quantum spin Hall phase in a wide range of thicknesses. The nontrivial topology originates from the intersurface coupling of the topological surface states of TCIs in the 3D limit. The intersurface coupling changes sign and gives rise to topological phase transitions as a function of film thickness. Furthermore, this coupling can be strongly affected by an external electric field, hence the quantum spin Hall phase can be effectively tuned under the experimentally accessible electric field.
Concise, aromatization-based approach to an elaborate C2-symmetric pyrenophane

A very short synthesis (5 steps), the crystal structure and resolution of an elaborate, inherently chiral [n](1,6)pyrenophane is reported. The synthesis hinges upon two very productive events: a multicomponent reaction and an unprecedented double-McMurry/valence isomerization/dehydrogenation step. Aromatization reactions are involved in the formation of all four of the rings of the pyrene system.
SIMULATIONS OF THE BOUNDARY LAYER BETWEEN A WHITE DWARF AND ITS ACCRETION DISK

Using a 2.5D time-dependent numerical code we recently developed, we solve the full compressible Navier-Stokes equations to determine the structure of the boundary layer (BL) between the white dwarf (WD) and the accretion disk in nonmagnetic cataclysmic variable systems. In this preliminary work, our numerical approach does not include radiation. In the energy equation, we either take the dissipation function (?) into account or we assume that the energy dissipated by viscous processes is instantly radiated away (? = 0). For a slowly rotating nonmagnetized accreting WD, the accretion disk extends all the way to the stellar surface. There, the matter impacts and spreads toward the poles as new matter continuously piles up behind it. We carry out numerical simulations for different values of the alpha-viscosity parameter (?), corresponding to different mass accretion rates. In the high viscosity cases (? = 0.1), the spreading BL sets off a gravity wave in the surface matter. The accretion flow moves supersonically over the cusp making it susceptible to the rapid development of gravity wave and/or Kelvin-Helmholtz shearing instabilities. This BL is optically thick and extends more than 30? to either side of the disk plane after only 3/4 of a Keplerian rotation period (tK = 19 s). In the low viscosity cases (? = 0.001), the spreading BL does not set off gravity waves and it is optically thin.
THE SIGNIFICANCE OF FLOW-MODIFIED PERMITTIVITY: A NEW MODEL AND COMPUTER SIMULATION OF ELECTRORHEOLOGY

We propose a model that takes into account the effect of flow-modified permittivity on electrorheology (ER). Due to dielectric relaxation, a shear flow causes the induced particle dipole moments in an ER fluid to tilt in a direction away from the direction of the applied DC electric field. Results from our computer simulation indicate that at high shear rates this misalignment (tilt angle) between the particle dipole moments and the applied electric field plays a crucial role in producing ER effects. By choosing particle-fluid dielectric and conductive mismatches to optimize the tilt angle, our simulation produces ER effects at much higher shear rates than those in earlier simulation work, even though there is no chain structure at these high shear rates. The increase in shear stress due to the applied electric field in our simulation is nearly constant over the wide range of shear rates examined, in qualitative agreement with experimental results. In addition, our model generates results that agree with earlier simulation work at low shear rates, where the particle dipole moments are essetially aligned with the field and the chain model is adequate.
Experimental characterization of the Ising model in disordered antiferromagnets

The current status of experiments on the d = 2 and d = 3 random-exchange and random-field Ising models, as realized in dilute anisotropic antiferromagnets, is discussed. Two areas of current investigation are emphasized. For d = 3, the large random field limit is investigated and equilibrium critical behavior is characterized at high magnetic concentrations.
Detection of renal dysfunction by point of care creatinine testing in patients undergoing peripheral MR angiography

To analyze the effectiveness of pre-study questionnaires in identifying at-risk patients as well as estimate the prevalence of chronic kidney disease (CKD), nephrogenic systemic fibrosis (NSF) risk factors, and other co-morbidities in patients scheduled to undergo magnetic resonance angiography (MRA) gadonlinium-based contrast agents (GBCA) studies.
Modular solar food dryers for farm use

Abstract Solar food dryer modules were constructed based on a low-cost, home solar dryer which used a unique parabolic trough reflector construction to increase radiation on the drying surface. Each module had a drying surface of 1.1 m 2 and a parabolic reflector area of 3.3 m 2 . Some were used for experiments to improve dryer design, while others were used to dry mango slices. The modular dryers were comparable in drying rates and quality of products to the smaller-scale dryers. They should be satisfactory for a semi-commercial, low-cost, intermediate technology drying process.
Multi-core performance studies of a Monte Carlo neutron transport code

Performance results are presented for a multi-threaded version of the OpenMC Monte Carlo neutronics code using OpenMP in the context of nuclear reactor criticality calculations. Our main interest is production computing, and thus we limit our approach to threading strategies that both require reasonable levels of development effort and preserve the code features necessary for robust application to real-world reactor problems. Several approaches are developed and the results compared on several multi-core platforms using a popular reactor physics benchmark. A broad range of performance studies are distilled into a simple, consistent picture of the empirical performance characteristics of reactor Monte Carlo algorithms on current multi-core architectures.
The Structure and the Distance of Collinder 121 from Hipparcos and Photometry: Resolving the Discrepancy

We present further arguments that the Hipparcos parallaxes for some of the clusters and associations represented in the Hipparcos catalog should be used with caution in the study of the Galactic structure. It has already been shown that the discrepancy between the Hipparcos and ground-based parallaxes for several clusters including the Pleiades, Coma Ber, and NGC 6231 can be resolved by recomputing the Hipparcos astrometric solutions with an improved algorithm diminishing correlated errors in the attitude parameters. Here we present new parallaxes obtained with this algorithm for another group of stars with discrepant data - the galactic cluster Cr 121. The original Hipparcos parallaxes led de Zeeuw et al. to conclude that Cr 121 and the surrounding association of OB stars form a relatively compact and coherent moving group at a distance of ≃550-600 pc. Our corrected parallaxes reveal a different spatial distribution of young stellar populace in this area. Both the cluster Cr 121 and the extended OB association are considerably more distant (750 - 1000 pc), and the latter has a large depth probably extending beyond 1 kpc. Therefore, not only are the recalculated parallaxes in complete agreement with the photometric uvbyβ parallaxes, but the structure of the field they reveal is no longer in discrepancy with that found by the photometric method.
Optomechanical cavity cooling of an atomic ensemble.

We demonstrate cavity sideband cooling of a single collective motional mode of an atomic ensemble down to a mean phonon occupation number $⟨n{⟩}_{\mathrm{min}﻿}={2.0}_{\ensuremath{-}0.3}^{+0.9}$. Both $⟨n{⟩}_{\mathrm{min}﻿}$ and the observed cooling rate are in good agreement with an optomechanical model. The cooling rate constant is proportional to the total photon scattering rate by the ensemble, demonstrating the cooperative character of the light-emission-induced cooling process. We deduce fundamental limits to cavity cooling either the collective mode or, sympathetically, the single-atom degrees of freedom.
N-Heterocyclic Carbene-Catalyzed Generation of Homoenolates: γ-Butyrolactones by Direct Annulations of Enals and Aldehydes

N-Heterocyclic carbenes, prepared in situ from diarylimidazolium salts, serve as highly effective catalysts for the generation of reactive homoenolates from alpha,beta-unsaturated aldehydes. The catalyst-bound homoenolate reacts with electrophilic aldehydes leading, via the key intermediacy of an activated carboxylate, to gamma-butyrolactones in good yields and stereoselectivities. Importantly, this process demonstrates an unprecedented reaction mode for the generation of nucleophilic carbanions with a multifunctional organocatalyst under exceptionally mild and convenient reaction conditions.
Femtosecond electron dynamics at the benzene/Ag(111) interface

Abstract The layer dependent evolution of the benzene/Ag(111) unoccupied electronic structure and electron dynamics have been investigated with time and angle resolved two photon photoemission. With the exception of one peak in the benzene multilayer photoelectron kinetic energy spectra, all excitations possess free electron-like dispersions parallel to the Ag(111) surface, consistent with image electronic states and not electron affinity levels in benzene molecular crystals. The non-dispersive peak in the benzene multilayer spectra is assigned to be an n=1 image state localized by structural disorder. The binding energy and lifetime of the n=1 image state has been measured for 1 to 5 layers of benzene. Adsorption of a benzene monolayer moves the n=1 image state electron closer to the metal, raising the n=1 binding energy from −0.77 eV to −0.84 eV and lowering the n=1 lifetime from 36 to 20 femtoseconds. Adsorption of a bilayer lowers the n=1 binding energy to −0.68 eV and raises the n=1 lifetime to 45 fs. The lifetime and binding energy remain constant from a bilayer to 5 layers of benzene. A dielectric continuum model successfully reproduces these trends in n=1 binding energy and lifetime. Analysis of the model potential and the calculated wavefunctions shows the layer independence of the multilayer n=1 lifetimes and binding energies to result from the trapping of the image state electron in the screened image potential within the benzene layer.
Solar neutrinos: Where we are, what we need

Abstract This talk compares standard model predictions for solar neutrino experiments with the results of actual observations. Here ‘standard model’ means the combined standard model of minimal electroweak theory plus a standard solar model. I emphasize the importance of recent analyses in which the neutrino fluxes are treated as free parameters, independent of any constraints from solar models, and the stunning agreement between the predictions of standard solar models and helioseismological measurements. In order to interpret solar neutrino experiments more accurately in terms of fundamental physics and astronomy, we need improved improved nuclear physics data. I describe the five most important nuclear physics problems whose solution is required for understanding the precise implications of solar neutrino experiments. Relevant preprints and references to other solar neutrino papers, as well as links to solar neutrino experiments, software, and numerical data are available at my Web site: http://www.sns.ias.edu/∼jnb. This Web site also contains a series of solar neutrino viewgraphys, with explanations, that can be downloaded.
Floating Reference Frames for Flexible Spacecraft

Floating reference frames which move with the flexible body under dynamic analysis offer the advantages of a linear vibration analysis in the presence of large system rotations. When the deformations of an elastic continuum are expanded in terms of the free-free modes on an unconstrained system, the rigid body modes are found to be fixed in a reference frame called the Tisserand frame, with respect to which the relative momentum is zero. This result also guarantees the independence of small variations of frame motions and coordinates for all modes with nonzero natural frequencies, a condition which can greatly simplify the formulation of equations of motion. A Modified Tisserand Constraint is introduced in order to define a floating reference frame with similar properties for an elastic body which contains spinning rotors.
Evaluation of a cost-effective loads approach

A shock spectra/impedance method for loads predictions is used to estimate member loads for the Viking Orbiter, a 7800-lb interplanetary spacecraft that has been designed using transient loads analysis techniques. The transient loads analysis approach leads to a lightweight structure but requires complex and costly analyses. To reduce complexity and cost, a shock spectra/impedance method is currently being used to design the Mariner Jupiter Saturn spacecraft. This method has the advantage of using low-cost in-house loads analysis techniques and typically results in more conservative structural loads. The method is evaluated by comparing the increase in Viking member loads to the loads obtained by the transient loads analysis approach. An estimate of the weight penalty incurred by using this method is presented. The paper also compares the calculated flight loads from the transient loads analyses and the shock spectra/impedance method to measured flight data.
Toward a growth-oriented model of financial programming☆

Abstract This paper attempts to contribute to the discussion of how to improve the design of Fund-supported financial programs so as to promote growth-oriented adjustment. The central issue examined is that of how to attain a desired balance-of-payments outcome without unduly sacrificing domestic output growth rates, especially when foreign capital inflows have been reduced and the exchange rate is being depreciated. A widely employed basic model of financial programming is extended to solve for the balance-of-payments outcome, growth in nominal income, and growth in capacity.
Determinants of corporate cash holdings: Evidence from spin-offs.

Abstract We study the factors that influence the cash allocation decision around a spin-off, using variables suggested by the trade-off theory, and controlling for the possible endogeneity of leverage and cash ratios. Spin-offs provide an opportunity to examine the determinants of cash allocation at the margin at the time of creation of a new entity. Our results indicate that managers allocate higher cash ratios to smaller firms, and firms with high research and development expense ratio, low net working capital ratio, and low leverage. Thus, higher cash ratios are correlated with difficulty of raising external capital and reduced availability of cash from internal sources. In addition, managers also base the cash allocation on observable immediate growth opportunities instead of on long-term possible growth. An analysis of excess cash ratios, defined as the difference between the actual and predicted cash ratios, indicate that firms are, on average, allocated less cash than suggested by trade-off models, and this deviation in allocated cash from predicted levels is explained only by concurrent profitability of the firms (a pecking order theory implication).
The crucial role of halogen atoms in the formation of Ta2S2C

Abstract The successful preparation of Ta2S2C at 1150 °C has been found to be intimately linked to the presence of halogens in the reaction. Adventitious chlorine obtained either through the use of excess carbon or of graphite crucibles was apparently responsible for previously successful reactions. The purposeful introduction of catalytic amounts (0.01 wt.%) of C6Cl6, C6Br6 or I2 into reactions containing stoichiometric amounts of tantalum, carbon and sulfur produces quantitative yields of Ta2S2C as measured by X-ray diffraction. Resistivity measurements made on a sintered pellet show Ta2S2C to be metallic between 300 and 4 K with a room temperature resistivity of approximately 2.2 × 10 −3 Ω cm .
On an outer bound and an inner bound for the general broadcast channel

In this paper, we study the Nair-El Gamal outer bound and Marton's inner bound for general two-receiver broadcast channels. We show that the Nair-El Gamal outer bound can be made fully computable. For the inner bound, we show that, unlike in the Gaussian case, for a degraded broadcast channel even without a common message, Marton's coding scheme without a superposition variable is in general insufficient for obtaining the capacity region. Further, we prove various results that help to restrict the search space for computing the sum-rate for Marton's inner bound. We establish the capacity region along certain directions and show that it coincides with Marton's inner bound. Lastly, we discuss an idea that may lead to a larger inner bound.
Cultural Amnesia, Cultural Nostalgia and False Memory: Africa’s Identity Crisis Revisited

Abstract The point of departure of this article is Ernest Renan’s observation that the secret of nation-building is to get one’s history wrong. We critically analyze – in the broader and historical context of the encounters between Africans and Europeans – the role of collective memory in its four functions of preservation, selection, elimination and invention. We focus on the first function to examine in depth how positive preservation of memory can become a form of nostalgia and how negative selection by memory can lead to elimination and amnesia. We argue that both nostalgia and amnesia can be forms of “getting one’s history wrong” in order to get one’s national identity right. We also attempt to show how historical invention can be consolidated into a false memory – placing something in the past which was never there before.
Inverse demand [4+2] cycloaddition reactions of allenamides: Reactivity scopes of an electron deficient variant of allenamines

Abstract The synthesis and reactivity of a series of new allenamides are described. These electron deficient variants of allenamines are more stable than allenamines but possess comparable reactivity. Particularly, oxazolidinone and imidazolidinone substituted allenamides undergo efficient inverse demand [4+2] cycloaddition reactions with heterodienes, leading to unique pyranyl heterocycles. The reactivity differences between various allenamides containing different substitution patterns around the nitrogen atom are illustrated.
From moment graphs to intersection cohomology

We describe a method of computing equivariant and ordinary intersection cohomology of certain varieties with actions of algebraic tori, in terms of structure of the zero- and one-dimensional orbits. The class of varieties to which our formula applies includes Schubert varieties in flag varieties and affine flag varieties. We also prove a monotonicity result on local intersection cohomology stalks.
Indenes via fulvene intermediates

Abstract Substituted indenes are prepared from 1,4-dicarbonyl compounds by treatment with base and cyclopentadiene.
Reflection-transmission phase shift: interferometer and viewing optics.

The interferometer and viewing optics that are the main optical components of an automated surface mapping system used to characterize the surface topography and the wall thickness uniformity of opaque and transparent spherical shells are described. To characterize surface finish or wall thickness of spherical shells with an accuracy of 10 nm and a resolution of 1 μm, the differential phase shift between two beams of orthogonal polarizations is measured before and after the probe beam has interacted with the test object.
Supervision and cost efficiency in banking

This paper suggests a link between bank operating efficiency and federal supervisor. Since supervisory priorities can vary by the context in which the supervisor was conceived, resulting differences in supervisory policies and procedures may underlay differences in the operating efficiency of their supervised banks. The effect on bank operating expenses is estimated at the individual bank level for each of four size strata using a translog cost function, controlling for bank characteristics and the impact of scale and scope economies. Results generally support a conclusion that bank operating cost differences exist by supervisor, except in the largest size stratum.
Diastereoselective synthesis of the cis-octahydronaphthalene nucleus of superstolides A and B

Abstract A highly diastereoselective synthesis of 4 via the intramolecular Diels-Alder reaction of trienal 3 is described.
Glueballs and their Kaluza-Klein cousins

Spectra of glueball masses in non-supersymmetric Yang-Mills theory in three and four dimensions have recently been computed using the conjectured duality between superstring theory and large N gauge theory. The Kaluza-Klein states of supergravity do not correspond to any states in the Yang-Mills theory and therefore should decouple in the continuum limit. On the other hand, in the supergravity limit g_(YM)^2 N → ∞, we find that the masses of the Kaluza-Klein states are comparable to those of the glueballs. We also show that the leading (g_(YM)^2N)^(-1) corrections do not make these states heavier than the glueballs. Therefore, the decoupling of the Kaluza-Klein states is not evident to this order.
Bounded degree graph inference from walks

Aslam and Rivest considered the problem of inferring the smallest edge-colored graph of degree bound k consistent with the sequence of colors seen in a walk of the graph. Using Church-Rosser properties of certain sets of rewrite rules, they gave a polynomial time algorithm for the case of k = 2. The straightforward implementation of their ideas results in an O(n^5) algorithm, where n is the length of the walk. In this paper, we develop their ideas further and give an O(n log n) algorithm for the same problem. We also show that if the degree bound k is greater than two, then the decision version of the problem is NP-complete, thus settling a conjecture of Aslam and Rivest.
Isospectral simply-connected homogeneous spaces and the spectral rigidity of group actions

We generalize Sunada's method to produce new examples of closed, locally non-isometric manifolds which are isospectral. In particular, we produce pairs of isospectral, simply-connected, locally non-isometric normal homogeneous spaces. These pairs also allow us to see that in general group actions with discrete spectra are not determined up to measurable conjugacy by their spectra. In particular, we show this for lattice actions.
Kinetics of the reactions of acenaphthene and acenaphthylene and structurally‐related aromatic compounds with OH and NO3 radicals, N2O5 and O3 at 296 ± 2 K

The kinetics of the atmospherically important gas-phase reactions of acenaphthene and acenaphthylene with OH and NO3 radicals, O3 and N2O5 have been investigated at 296 ± 2 K. In addition, rate constants have been determined for the reactions of OH and NO3 radicals with tetralin and styrene, and for the reactions of NO3 radicals and/or N2O5 with naphthalene, 1- and 2-methylnaphthalene, 2,3-dimethylnaphthalene, toluene, toluene-α,α,α-d3 and toluene-d8. The rate constants obtained (in cm3 molecule−1 s−1 units) at 296 ± 2 K were: for the reactions of O3; acenaphthene, <5 × 10−19 and acenaphthylene, ca. 5.5 × 10−16; for the OH radical reactions (determined using a relative rate method); acenaphthene, (1.03 ± 0.13) × 10−10; acenaphthylene, (1.10 ± 0.11) × 10−10; tetralin, (3.43 ± 0.06) × 10−11 and styrene, (5.87 ± 0.15) × 10−11; for the reactions of NO3 (also determined using a relative rate method); acenaphthene, (4.6 ± 2.6) × 10−13; acenaphthylene, (5.4 ± 0.8) × 10−12; tetralin, (8.6 ± 1.3) × 10−15; styrene, (1.51 ± 0.20) × 10−13; toluene, (7.8 ± 1.5) × 10−17; toluene-α,α,α-d3, (3.8 ± 0.9) × 10−17 and toluene-d8, (3.4 ± 1.9) × 10−17. The aromatic compounds which were observed to react with N2O5 and the rate constants derived were (in cm3 molecule−1 s−1 units): acenaphthene, 5.5 × 10−17; naphthalene, 1.1 × 10−17; 1-methylnaphthalene, 2.3 × 10−17; 2-methylnaphthalene, 3.6 × 10−17 and 2,3-dimethylnaphthalene, 5.3 × 10−17. These data for naphthylene and the alkylnaphthalenes are in good agreement with our previous absolute and relative N2O5 reaction rate constants, and show that the NO3 radical reactions with aromatic compounds proceed by overall H-atom abstraction from substituent-XH bonds (where X = C or O), or by NO3 radical addition to unsaturated substituent groups while the N2O5 reactions only occur for aromatic compounds containing two or more fused six-membered aromatic rings.
A Preliminary Proposition for a Test Method to Measure (Impact) Damage Resistance

A preliminary proposal for a test to determine the impact damage resis tance of composite materials and their structures is offered. This test is centered on the utility of contact force as a parameter directly related to the damage that occurs during the event. This is demonstrated through work previously published as well as via new experi ments conducted on various graphite/epoxy material systems and laminates in both mono lithic laminate and sandwich configurations. Static indentation and impact tests were con ducted and show a similarity in regards to the structural response and the damage that occurs. This proposal is discussed in terms of the laminates tested and the results, the test's general applicability and utility, and issues that need to be addressed further. The proposal makes a significant step towards providing a common reference point and language for (impact) damage resistance.
X-Ray Emission from the Planet Pulsar B1257+12

We report the detection of the millisecond pulsar B1257+12 with the Chandra X-ray Observatory. In a 20 ks exposure we detected 25 photons from the pulsar, with energies between 0.4 and 2.0 keV, corresponding to the flux FX = (4.4 ± 0.9) × 10-15 ergs s-1 cm-2 in this energy range. The X-ray spectrum can be described by a power-law model with photon index Γ ≈ 2.8 and luminosity LX ≈ 2.5 × 1029 ergs s-1 in the 0.3-8 keV band, for a plausible distance of 500 pc and hydrogen column density NH = 3 × 1020 cm-2. Alternatively, the spectrum can be fitted by a blackbody model with kT ≈ 0.22 keV and projected emitting area ~2000 m2. If the thermal X-rays are emitted from two symmetric polar caps, the bolometric luminosity of the two caps is 2Lbol ~ 3 × 1029 ergs s-1. We compared our results with the data on other 30 millisecond pulsars observed in X-rays and found that the apparent X-ray efficiency of PSR B1257+12, LX/Ė ~ 3 × 10-5 for d = 500 pc, is lower than those of most millisecond pulsars. This might be explained by an unfavorable orientation of the X-ray pulsar beam if the radiation is magnetospheric, or by strong asymmetry of polar caps if the radiation is thermal (e.g., one of the polar caps is much brighter than the other and remains invisible for most part of the pulsar period). Alternatively, it could be attributed to absorption of X-rays in circumpulsar matter, such as a flaring debris disk left over after formation of the planetary system around the pulsar.
Osborne Reynolds : energy methods in transition and loss production : a centennial perspective

Osborne Reynolds' developments of the concepts of Reynolds averaging, turbulence stresses, and equations for mean kinetic energy and turbulence energy are viewed in the light of 100 years of subsequent flow research. Attempts to use the Reynolds energy-balance method to calculate the lower critical Reynolds number for pipe and channel flows are reviewed. The modern use of turbulence-energy methods for boundary layer transition modeling is discussed, and a current European Working Group effort to evaluate and develop such methods is described. The possibility of applying these methods to calculate transition in pipe, channel, and sink flows is demonstrated using a one-equation, q-L, turbulence model. Recent work using the equation for the kinetic energy of mean motion to gain understanding of loss production mechanisms in three-dimensional turbulent flows is also discussed
Stability properties and cross coupling performance of the control allocation scheme CAPIO

This paper presents a stability analysis and an application of a recently developed algorithm to recover from Pilot Induced Oscillations (CAPIO). When actuators are ratesaturated due to either an aggressive pilot command, high gain of the ight control system or some anomaly in the system, the eective delay in the control loop may increase. This eective delay increase manifests itself as a phase shift between the commanded and actual system signals and can instigate Pilot Induced Oscillations (PIO). CAPIO reduces the eective time delay by minimizing the phase shift between the commanded and the actual attitude accelerations. To establish theoretical results pertinent to CAPIO stability analysis, a scalar case is presented. In addition, we present simulation results for aircraft with cross-coupling which demonstrates the potential of CAPIO serving as an eective PIO handler in adverse conditions.
Breaking down the barriers: Competition, syndicate structure, and underwriting incentives

Abstract We argue that the entry of commercial banks into bond underwriting led to the evolution of co-led underwriting arrangements and lowered the screening incentives of underwriters. Lead underwriters in co-led syndicates faced weaker incentives to screen issuer quality. In boom markets, issues underwritten by co-led syndicates were more likely to be involved in financial misrepresentation events. Underwriter incentives in co-led syndicates were particularly weak in industries where commercial banks stole substantial market share. Similar patterns do not hold in bust markets where investors are likely to engage in their own information collection efforts. Our results suggest that competition may have an adverse effect on the incentives of financial intermediaries in market environments where their information production is more valuable to investors.
Astrometric detection of exo-Earths in the presence of stellar noise

Astrometry from space is capable of making extremely precise measurements of the positions of stars, at angular precision of well below 1 micro-arcsecond (uas) at each visit. Hundreds of visits over a period of five years could achieve a relative astrometric precision for the mission of below 0.05 uas; this is well below the astrometric signature of 0.3 uas for a Sun-Earth system at a distance of 10 pc. The Sun's photometric fluctuations on time scales from days to years are dominated by the rotation and evolution of stellar surface features (sunspots and faculae). This flux variability is a source of astrophysical noise in astrometric as well as radial velocity (RV) measurements of the star. In this paper we describe a dynamic starspot model that produces flux variability which is consistent with the measured photometric power spectra of the Sun and several other stars. We use that model to predict the jitter in astrometric and RV measurements due to starspots. We also employ empirical stellar activity models to estimate the astrometric jitter of a much larger sample of stars. The conclusion of these simulations is that astrometric detection of planets in the habitable zones of solar-type stars is not severely impacted by the noise due to starspots/faculae, down to well below one Earth mass.
Heavy quarks and long-lived hadrons

In a recent Letter we reported on some work which led us to suggest the possibility of narrow spikes in the e+e- annihilation cross section into hadrons. In this paper, we discuss the theoretical infrastructure of this work more thoroughly, and improve and extend the calculations and experimental predictions. We examine a colored quark-gluon model of hadronic matter, with color an exact SU(3) gauge symmetry. In addition to the light quarks that make up ordinary hadrons, a heavy quark, such as the charmed c, is included. The narrow resonances recently discovered by the MIT-BNL and SLAC-LBL groups are interpreted as cc bound states (orthocharmonium). In this energy range, the effective coupling has become small according to asymptotic freedom, and many aspects of the bound-state structure can be calculated. The existence of 0-(paracharmonium) states is predicted, and decay widths and mass splittings are estimated. The total e+e- cross section into hadrons is predicted to scale asymptotically, with an approach to scaling from above that can be calculated over a large energy range.
Correlation of EBIC and SWBXT Imaged Defects and Epilayer Growth Pits in 6H-SiC Schottky Diodes

We show the first direct experimental correlation between the presence of closed core screw dislocations in 6H-SiC epilayers with recombination centers, as well as with some of the small growth pits on the epilayer surface in lightly-doped 6H-SiC Schottky diodes. At every Synchrotron White-Beam X-ray Topography (SWBXT)-identified closed core screw dislocation, an Electron Beam Induced Current (EBIC) image showed a dark spot indicating a recombination center, and Nomarski optical microscope and Atomic Force Microscope (AFM) images showed a corresponding small growth pit with a sharp apex on the surface of the epilayer.
Does Recognition versus Disclosure Affect Value Relevance? Evidence from Pension Accounting

ABSTRACT: This study examines whether institutional ownership and analyst following affect the value relevance of disclosed versus recognized pension liabilities. Using a sample of firms with pension liabilities that were disclosed under SFAS No. 87 and subsequently recognized under SFAS No. 158 from 1999 to 2007, I find that off-balance-sheet pension liabilities are more value relevant for firms with a higher level of institutional ownership or analyst following in the pre-158 period. More importantly, I find that SFAS No. 158 increases the value relevance of previously disclosed off-balance-sheet pension liabilities for firms with a low level of institutional ownership or analyst following, and that the increase in the value relevance becomes less pronounced for firms with a higher level of institutional ownership or analyst following. Overall, the results are consistent with the view that institutional ownership and analyst following affect the value relevance of disclosed information as well as the va...
On the Endogenous Choice between Protection and Promotion

In a model of strategic interaction between firms in lobbying activity, I show that capitalists might prefer tariffs (protection) to production subsidies (promotion). This is due to the congestion problem arising from the government's convex welfare costs of providing subsidies as opposed to both the free-rider problem and the congestion problem acting in opposite directions in the case of tariffs. If an industry association exists, coordination can be achieved when lobbying for tariffs, but not in the case of production subsidies.
Surface/interface X-ray diffraction

Abstract The structural challenges presented by the two-dimensional (2D) world of surfaces and interfaces have proven formidable. In spite of the critical role that they play in such diverse sciences as catalysis, tribology, metallurgy, and electronic devices and in spite of the expected richness of two-dimensional physics of melting, magnetism, and related phase transitions, only a few surface structures are known and most of those only semiquantitatively (e.g., their symmetry). Our inability in many cases to understand atomic structure and to make the structure/properties connection in the 2D region of surfaces and interfaces has significantly inhibited progress in understanding this rich area of science. Furthermore, the synthesis of new materials has played a key role in modern industrial evolution, and this synthesis is also the foundation of contemporary materials research. Many of the new materials fabrication processes are based on crystal growth and thin film deposition techniques, such as molecular beam epitaxy (MBE), chemical vapor deposition (CVD), liquid phase epitaxy (LPE), sputtering deposition, laser ablation and electrochemical plating. To improve the development and engineering of materials based on these techniques, it is essential to have a detailed understanding of the fundamental interactions and effects pertaining to the basic surface and interface structures. This knowledge will allow scientists and engineers to predict and control material properties based on the processing parameters and resulting configurations. This knowledge will be useful also for the understanding of modern composites, ceramics, and nanophase materials in which surfaces and interfaces play a large role in determining their physical and chemical characteristics. With the advent of high-brilliance synchrotron radiation sources and improved analytical methods, surface-sensitive X-ray techniques have recently been developed to study the structure and the associated reactions/transformations at surfaces and interfaces. These synchrotron X-ray techniques have already proven to be a powerful tool to probe surfaces/interfaces beyond the capabilities of earlier experimental methods involving electrons, ions, neutrons and light. This paper will discuss the general principles and experimental method of surface/interface X-ray diffraction as well as provide several examples to demonstrate the usefulness of the techniques applied to surface/interface problems.
The effect of small-diameter H-graft portacaval shunts on portal blood flow.

BACKGROUND : Small-diameter prosthetic H-graft portacaval shunts have been shown to promote preservation of total hepatic blood flow relative to large-diameter H-graft shunts. Nonetheless, specific changes in portal hemodynamics occurring with small-diameter H-graft shunting are unknown. This study was undertaken to evaluate changes in portal flow that occur with these shunts. METHODS : Portal vein and inferior vena cava (IVC) blood flow were determined intraoperatively in 36 consecutive adults before and after prosthetic H-graft portacaval shunting using color-flow Doppler ultrasound. Postshunt measurements were made immediately cephalad and caudad to the shunt. Comparisons were undertaken using a paired Student's t-test with 95% confidence. RESULTS : Portal pressures decreased in all (P <0.001), but never to normal. Postshunt portal flow cephalad and caudad to the shunt were not different from preshunt flow (P = 0.09, P = 0.28, respectively), although they were different from each other (P = 0.004). Postshunt IVC flow cephalad to the shunt was greater than caudad IVC flow (P = 0.004) and greater than preshunt IVC flow (P <0.001), reflecting high flow through the shunt into the IVC. CONCLUSIONS : Small-diameter prosthetic H-graft portacaval shunts divert a significant amount of blood from the portal vein and significantly decrease portal pressures. The decreases in portal pressures with shunting are significant whereas changes in portal blood flow into the liver are not. These findings help explain the low incidence of variceal rebleeding and hepatic dysfunction after these shunts.
Optimal Estimation and Rank Detection for Sparse Spiked Covariance Matrices.

This paper considers a sparse spiked covariance matrix model in the high-dimensional setting and studies the minimax estimation of the covariance matrix and the principal subspace as well as the minimax rank detection. The optimal rate of convergence for estimating the spiked covariance matrix under the spectral norm is established, which requires significantly different techniques from those for estimating other structured covariance matrices such as bandable or sparse covariance matrices. We also establish the minimax rate under the spectral norm for estimating the principal subspace, the primary object of interest in principal component analysis. In addition, the optimal rate for the rank detection boundary is obtained. This result also resolves the gap in a recent paper by Berthet and Rigollet (Ann Stat 41(4):1780–1815, 2013) where the special case of rank one is considered.